ITS2.2/SSP1.2 | Achievements and perspectives in scientific ocean and continental drilling
EDI
Achievements and perspectives in scientific ocean and continental drilling
JpGU
Convener: Thomas Wiersberg | Co-conveners: Angelo Camerlenghi, Cindy KunkelECSECS, Jorijntje Henderiks, Harue Masuda
Orals
| Thu, 27 Apr, 10:45–12:30 (CEST), 14:00–17:45 (CEST)
 
Room N1
Posters on site
| Attendance Thu, 27 Apr, 08:30–10:15 (CEST)
 
Hall X3
Orals |
Thu, 10:45
Thu, 08:30
Scientific drilling through the International Ocean Discovery Program (IODP) and the International Continental Scientific Drilling Program (ICDP) continues to provide unique opportunities to investigate the workings of the interior of our planet, Earth’s cycles, natural hazards and the distribution of subsurface microbial life. The past and current scientific drilling programs have brought major advances in many interdisciplinary fields of socio-economic relevance, such as climate and ecosystem evolution, palaeoceanography, the deep biosphere, sustainable georesources, deep crustal and tectonic processes, geodynamics and geohazards. This session invites contributions that present and/or review recent scientific results from deep Earth sampling and monitoring through ocean and continental drilling projects. Furthermore, we encourage contributions that outline perspectives and visions for future drilling projects, in particular projects using a multi-platform approach.

Orals: Thu, 27 Apr | Room N1

Chairpersons: Thomas Wiersberg, Harue Masuda, Jorijntje Henderiks
10:45–10:50
10:50–11:00
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EGU23-1869
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On-site presentation
Henning Lorenz, Jan-Erik Rosberg, and Christopher Juhlin and the COSC-2 operations team

The Collisional Orogeny in the Scandinavian Caledonides (COSC) multi-disciplinary scientific drilling project characterises the structure and orogenic processes involved in a major collisional mountain belt. Located in western central Sweden, the project drilled its second fully cored borehole, COSC-2, during spring and summer 2020. It extends the COSC composite geological section, which above is composed of outcrops at Åreskutan mountain and the COSC-1 scientific borehole (drilled 2014), through the nappes of the Caledonian Lower Allochthon, the main décollement and the upper kilometre of basement rocks. In summary, the retrieved geological section differs partially from the expected geological section with respect to the depth to the main décollement and the expected rock types. COSC-2 targets include the characterisation of orogen-scale detachments, the impact of orogenesis on the basement below the detachment, and the Early to Lower Ordovician(?) palaeoenvironment on the outer margin of palaeocontinent Baltica. This is complemented by research on heat flow, groundwater flow, gas compositions and characterisation of the microbial community in the present hard rock environment of the relict mountain belt.

COSC-2 successfully, and within budget, recovered a continuous drill core to 2276 m depth. On-site scientific investigations on the drill core by experts were impeded by travel restrictions due to the Covid-19 pandemic. Thus, the core was first completely described in late 2021 at the BGR Core Repository for Scientific Drilling (Berlin Spandau, Germany). After further delay, the sampling party was held in mid-2022.

The entire operations, technical and scientific, were conducted on a 1600 m2 drill site. COSC-2 was drilled by the Swedish national research infrastructure for scientific drilling, Riksriggen, with a core recovery close to 100 %. Drilling was performed with water as drilling fluid. Biodegradable polymers were added for drilling in greater depth to reduce friction. Down to 1576 m, HQ triple tube drilling was used (96 mm hole diameter, 61 mm core diameter), followed by NQ triple and double tube drilling to total depth (76 mm hole diameter, 45/48 mm core diameter). Drilling was directly followed by extensive downhole surveying. In autumn 2021, a major surface and borehole seismic survey was conducted, covering approximately an area of 20 km2 around the borehole. In 2022, fluid-conducting zones were investigated and fluids sampled with different methods for geochemical (gas and fluid) and microbiological analysis.

The drill site was restored in 2022, leaving a 35 m long and 4 m wide access road to the borehole. This is sufficient for COSC-2 long-term downhole investigations. The borehole is also available for research that is not part of the original COSC project. However, observations during recent downhole investigations suggest that sedimentation with a rate of several tens of meters per year successively is limiting access to the deepest part of the borehole. Scientific results from the COSC project are presented in session TS6.4 "The Caledonian Orogen of the North Atlantic region: insights from geological and geophysical studies".

How to cite: Lorenz, H., Rosberg, J.-E., and Juhlin, C. and the COSC-2 operations team: The COSC-2 scientific drilling project: summary of science, operations, management and legacy, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1869, https://doi.org/10.5194/egusphere-egu23-1869, 2023.

11:00–11:10
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EGU23-11174
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Highlight
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On-site presentation
Othmar Müntener, György Hétenyi, Andrew Greenwood, Luca Ziberna, Alberto Zanetti, Mattia Pistone, and Donato Giovanelli and the DIVE Drilling Project Science Team

We report preliminary results from drill cores and logging from the ICDP Drilling the Ivrea-Verbano zonE (DIVE) project, Hole DT-1b in Ornavasso (Val d’Ossola, northern Italy). Characterized by pronounced geophysical anomalies, the exposed Ivrea-Verbano Zone in the Italian Alps represents an archetypal lower continental crust section. The first phase of DIVE is dedicated to the drilling and the petrological and geophysical characterization of the lowermost continental crust. Specifically, Hole DT-1b was set in the in the hinge zone of the Massone Antiform to explore the pre-Permian lithologies of the lower continental crust. Hole DT-1b was drilled using the diamond double tube continuous wireline coring method, from October 6 to December 10, 2022, and the retrieved rock cores were inspected and classified by the DIVE drilling project science team. Core recovery was effectively 100% throughout the entire drill hole. In total, 578m of the upper part of the lower continental crust in the Ivrea-Verbano Zone were drilled and cored.

Here we summarize on site visual core descriptions and preliminary geophysical logging and microbiological investigations. The cores mostly consist of amphibolites and garnet-bearing metapelites with variable presence of migmatitic structures, and with local high and low temperature shear zones, pegmatitic dikes, and open fractures.

Continuous monitoring of borehole fluids and gases (OLGA and miniRuedi devices, see EGU abstract by Dutoit and coworkers), and a suite of borehole logging measurements (see abstract by Li, Greenwood, Caspari and coworkers) were performed. They match very well the core logs performed on site (magnetic susceptibility and natural gamma radiation). The most prominent, directly observable deformation feature was a high-temperature foliation, with a dip angle between 30 and 60° in the upper part of the hole, becoming increasingly steeper in the deeper part.

Along the entire drill hole fractures and open cracks were observed, some of them filled with precipitates of quartz, carbonates, sulphides and oxides. These fractures are potentially promising hosts for microbial communities and are currently under investigation. Additional samples for microbiological studies were taken every 20m from the drill cores and are currently cultivated for further investigations.

Hole DT-1b provides detailed insights into the compositional, structural and geophysical variation of metasedimentary continental lower crust, including the distribution of sulphides. Relamination of metamorphic pelitic and mafic rocks may produce an important reservoir of sulphur bearing minerals in the lower continental crust. Further results emerging between abstract submission and the conference will be presented.

How to cite: Müntener, O., Hétenyi, G., Greenwood, A., Ziberna, L., Zanetti, A., Pistone, M., and Giovanelli, D. and the DIVE Drilling Project Science Team: Preliminary results from the ICDP - DIVE project: Hole DT-1b (Ornavasso, Italy), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11174, https://doi.org/10.5194/egusphere-egu23-11174, 2023.

11:10–11:20
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EGU23-15184
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ECS
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On-site presentation
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Damian Pasiecznik, Andrew Greenwood, György Hetényi, and Florian Bleibinhaus

The Ivrea Verbano Zone (IVZ) is one of the most complete crust upper-mantle geological references in the world, an area that the Drilling the Ivrea-Verbano zone project (DIVE) aims to study. Associated with the IVZ, the Ivrea Geophysical Body (IGB) is of particular interest, as it is a structure beneath the IVZ characterized by high seismic velocities and a strong gravity anomaly. Recent studies across the IGB indicate that dense mantle rocks are located at depths as shallow as ca. 3 km. Several geological, geochemical and geophysical studies are planned, including the drilling of a 4 km deep borehole that will cross the crust–mantle transition zone, and provide, for the first time, geophysical in situ measurements of the IGB.

In preparation for the drilling campaign, a seismic survey was performed in October 2020 in collaboration with GFZ Potsdam, Université de Lausanne, and Montanuniversität Leoben. In this study, we present results from a shallow seismic survey across the Blamuccia Peridotite, where the prospective drill site is planned. The survey was carried out with a fixed spread of 200 vertical geophones and 160 3C-sensors, spaced at 11 m along three sub-parallel lines 50-80 m apart. Vibroseis source points were at 22 m stations along a 2.2 km line utilizing a 12-140 Hz 10 s linear sweep with 3 s listening time.

Through the application of 3D traveltime tomography, a shallow velocity model was obtained. The model shows a good correlation with the surface geology and can outline the east and west boundaries of the peridotite body; however, it is not deep enough to interpret its relationship with the mantle. Velocity analyses performed through the tomography process show that the peridotite body must have a P-wave velocity at least greater than 7.3 km/s, which is consistent with the high velocities measured in several laboratory studies from samples throughout the area.

Seismic data show a lack of reflectors from the peridotite body, which could be interpreted in two ways: The peridotite body is attached to the mantle, or its structure is such that reflections from its boundaries cannot be detected by our seismic survey due to its limited aperture. However, a deep reflector was observed in some shot gathers, originating from a depth between 2-3 km from sea level. This corresponds well to the depth of the crust-mantle transition estimated from gravity and receiver function surveys. The shallow 3D velocity was used for the application of refraction statics and the development of a deeper velocity model to perform 3D pre-stack depth migration. Extreme topography, high P-wave velocities, and vertical geological structures present a challenge for the imaging process.

How to cite: Pasiecznik, D., Greenwood, A., Hetényi, G., and Bleibinhaus, F.: 3D Tomography across the Balmuccia Peridotite, Ivrea Zone, Italy - Project DIVE, phase two, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15184, https://doi.org/10.5194/egusphere-egu23-15184, 2023.

11:20–11:30
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EGU23-12837
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ECS
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On-site presentation
Wiebke Schäfer, Manuel Keith, Marcel Regelous, Reiner Klemd, and Martin Kutzschbach

Immiscible sulphide liquids, preserved as magmatic sulphide droplets, are believed to strongly control the partitioning behaviour of chalcophile trace elements [1-2]. Hence, the chemical composition of sulphide droplets can be used to understand the fractionation processes of chalcophile elements in magmatic systems that reached sulphide saturation. We carried out LA-ICP-MS analysis of sulphide droplets from gabbros of the lower oceanic crust recovered by deep ocean drilling from mid-ocean ridge spreading centres in the Pacific (ODP147), Indian (ODP176, ODP179, IODP360) and the Atlantic (OPD209 and IODP305) Oceans. For comparison, sulphide droplets from mid-ocean ridge basalts from the East Pacific Rise, Mid-Atlantic Ridge and Southwest Indian Ridge were analysed. Our results show that most gabbros host abundant large magmatic sulphide droplets (mostly above 100 µm up to 1 mm) significantly exceeding those from the related lava units [2-4]. The droplets are commonly associated with or incorporated in olivine or clinopyroxene suggesting an early-stage sulphide saturation but are locally also incorporated in Fe-oxides indicating a later-stage formation during magma cooling [4-5]. The Ni contents of sulphide droplets hosted in gabbros from Hess Deep (Pacific Ocean) are highly variable ranging from ~10 µg/g to weight % levels. Nickel is also strongly controlled by olivine fractionation, and thus can be seen as a parameter indicating whether sulphide saturation was reached before or after the onset of olivine crystallisation. Due to the highly variable Ni contents and in combination with petrographic observations, we suggest that the magma reached early sulphide saturation at Hess Deep, as typically seen in mid-ocean ridge magmatic systems. However, the variable Ni contents in the sulphide droplets indicate that the magma was sulphide-saturated over a longer time span. Alternatively, the magma may frequently switch between being sulphide undersaturated and saturated, due to decreasing pressure during magma ascent accompanied by crystal fractionation at different levels in the crust. Generally, the trace element composition of the sulphide droplets hosted by gabbros from the different drill sites overlap. However, there are significant differences in the compositions of sulphide droplets from lava samples and from associated gabbroic xenoliths [4]. Thus, analysis of droplets from lavas alone provide an incomplete picture of the chalcophile element evolution of the magmatic system. We find no clear differences in sulphide composition with spreading rate or degree of melting as suggested for the silicate melt portion. Instead, the composition of sulphide droplets indicates that fractionation during magma ascent in the crust is the main driver that causes the observed chemical variations, which is part of ongoing investigations.

[1] Wood, B. J. and Kiseeva, E. S. (2015), Earth and Planetary Science Letters, 424, 280-294. [2] Patten, C. et al. (2013), Chemical Geology, 358, 170–188. [3] Peach et al. (1990), Geochimica et Cosmochimica Acta, 12, 3379-3389. [4] Keith, M. et al. (2017), Chemical Geology, 451, 67–77. [5] Jenner, F. E. et al. (2010), Journal of Petrology, 51, 2445-2464.

How to cite: Schäfer, W., Keith, M., Regelous, M., Klemd, R., and Kutzschbach, M.: How scientific ocean drilling helps to decode chalcophile trace element behaviour in mid-ocean ridge magmatic systems, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12837, https://doi.org/10.5194/egusphere-egu23-12837, 2023.

11:30–11:40
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EGU23-11508
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ECS
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On-site presentation
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Natalia Banasiak and Florian Bleibinhaus

In our study we investigate the subsurface velocity structure of the Cheb Basin (Czech Republic) based on shallow high-resolution 2D seismic data collected in the years 2014-2020. The Cheb Basin is a small intracontinental basin, located in the north-west part of the Bohemian Massif and at the western end of the Cenozoic Eger Rift. The basin and underlying crustal structure are the subject of the ongoing International Continental Scientific Drilling Program (ICDP) “Drilling the Eger Rift''. Our surveys aim to investigate the up to 350-m-thick Miocene and Quaternary sediments and the bedrock, made of Paleozoic Variscan units and post-Variscan granites.

Four datasets were collected, each with a 480-m-long split-spread of single geophones at 2 m spacing. The 2014 dataset was acquired with a 10 m source interval, mainly with a weight-drop source and partly with a SISSY source, resulting in an almost 3 km long profile. The 2017, 2020 line 1 and 2020 line 2 datasets were shot with a buffalo gun at a 20 m source interval. Their lengths are 2 km, 0.8 km and 1 km respectively.

We present the traveltime tomography output for all 4 profiles, which brings important information about the subsurface. The results give us insight into the velocities of the sediments, which in this area mainly range from 600 m/s to 2500 m/s. The bedrock is observed with velocities up to 4500 m/s and is present at a depth of around 250 m below the surface. This velocity information is complimented by the preliminary results of the ongoing reflection processing.

How to cite: Banasiak, N. and Bleibinhaus, F.: Seismic structure of the Cheb Basin from high resolution surveying – traveltime tomography results, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11508, https://doi.org/10.5194/egusphere-egu23-11508, 2023.

11:40–11:50
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EGU23-4047
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On-site presentation
Masataka Kinoshita, Rie Nakata, Yoshitaka Hashimoto, Yohei Hamada, Laura Wallace, Tianhaozhe Sun, Eiichiro Araki, and Yusuke Yamashita

Shallow slow earthquakes, which last minutes to years, are important indicators of subduction megathrust slip behavior and future seismic and tsunami potential. Subducting plate roughness and seamounts have been proposed to promote slow earthquakes by inducing local geomechanical and hydrogeological anomalies. The Hyuga-Nada region offshore Kyushu, Japan is an outstanding locale for drilling and observatory experiments to investigate these effects. In this region, slow earthquakes are repeatedly observed on and near the subducting Kyushu-Palau-Ridge, KPR, chain of seamounts thus providing excellent opportunities to explore the effects of seamounts on geomechanical/hydrological/thermal properties, and ultimately seismic coupling. Long-term monitoring enabled by a planned permanent network (N-net) will allow subsurface processes during frequent (~1 year) periodical slow earthquakes and ~M7 earthquakes (~20-30 year interval) to be captured with high fidelity. Drilling, logging, and coring will provide key constraints on stress state, hydrological processes, and sediment physical properties in the region above the ridge.  We have originally proposed the drilling and monitoring plan to IODP in 2019 (Nakata et al. 2019). In this presentation, we report the updated proposal plan along with initial processing results of new site survey data acquired with JAMSTEC (Miura et al., 2021, Arai et al., 2021, Ma et al., 2021).

 

We propose to drill and install observatories at three primary locations in Hyuga-Nada to address two hypotheses: 1) Seamount subduction modulates stress and pore pressure, creates fracture networks and influences the thermal and hydrological state of the margin. 2) The spatiotemporal distribution of slow earthquakes is strongly influenced by seamount subduction through the processes outlined in Hypothesis 1. We will drill three primary distinct sites relative to the seamount, to (1) measure physical properties, and (2) describe deformation by LWD, APCT-3, and core analysis to characterize in-situ stress state, fracture density, heat flow, and pore fluid flow. Spatial variations in the upper plate disruption caused by seamount subduction will be revealed by comparing results from sites in the leading and lateral edges, and top of the currently subducting seamount; and these will constrain geomechanical, hydrological, and thermal models. At two of the sites, we will install a “Fiber-CORK” observatory equipped with conventional pressure and temperature sensors and cutting-edge fiber-optic sensors. One site may be connected to the N-net node for real-time data streaming. The combination will fill a gap in slip durations currently observable in this region with seismic and geodetic instrumentation. Fully characterizing slow earthquakes will reveal the degree to which they accommodate plate motion, and whether strain is accumulated for future earthquakes.

How to cite: Kinoshita, M., Nakata, R., Hashimoto, Y., Hamada, Y., Wallace, L., Sun, T., Araki, E., and Yamashita, Y.: Drilling and monitoring in Hyuga-Nada: Unveiling effects of ridge subduction on slow earthquakes, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4047, https://doi.org/10.5194/egusphere-egu23-4047, 2023.

11:50–12:00
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EGU23-4104
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Virtual presentation
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Hiroshi Ogasawara and the ICDP DSeis team

Limited access has hindered understanding of seismogenic zone and life at depth (e.g., ICDP Science Plan 2014-2019; 2020-2030). The 2014 M5.5 Orkney earthquake South Africa ruptured the entire vertical depth range, between 3.5 and 7 km of the West Rand Group (2.9 Ga metasedimentary formations with altered mafic/ultramafic sill/dyke complex). We could have a drilling rig at 2.9 km depth in hard-rock formations in West Rand Group at the Moab Khotsong gold mine. During 2017-2018, we accomplished NQ wireline full-core diamond drilling and downhole logging with a total length of 1.6 km (ICDP Thrill to Drill; Ogasawara et al. 2019; Nkosi et al. 2022). We could not make downhole logging at and below the intersections of the structure that hosted the Orkney main- and after-shocks. So, we exported the most critical section of the core to Center for Advanced Marine Core Research, Kochi University/Kochi Core Center (KCC) Japan to log and for further investigation. Mineral/geochemical studies (XRD, XRF, EPMA, SEM-EDS, X-ray CT, friction) at KCC, Hiroshima, Tohoku, Tokyo, and Kyoto Universities, as well as SPring8 elucidate the assemblage with talc and/or associated altered mafic minerals in greenschist facies and their mechano-chemical characteristics (e.g., Miyamoto et al. 2022; Yabe et al. 2023 GeoCongress). Our drilling also intersected the ancient hypersaline brine vein. US geomicrobiology team extensively investigated the brine (Oliver et al. 2022; Nisson et al. 2022). The outstanding outcomes include the age (>1Ga) and the salinity, the end-member in their research history since the 1990s. COVID-19 hindered, in particular, our research activity at 2.9 km depth at Moab Khotsong mine and access to the core during 2020-2021. However, we could log Holes A and B again in 2022 to compare with the previous logging data. This paper overviews the activity mentioned above, as well as prospects.

Our research is financially supported by ICDP, JSPS, JST-JICA, MEXT Japan, US NSF, German DFG, SA NRF, Ritsumeikan Univ., GFZ. Kochi Core Center, Astrobiology Center.

How to cite: Ogasawara, H. and the ICDP DSeis team: ICDP Drilling into Seismogenic zones in South African mines (DSeis; 2016 – onwards), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4104, https://doi.org/10.5194/egusphere-egu23-4104, 2023.

12:00–12:10
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EGU23-8462
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Highlight
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On-site presentation
Lauro Chiaraluce, David Mencin, Rick Bennett, Massimiliano R. Barchi, and Marco Bohnhoff and the STAR team

Earthquakes are complex natural phenomena that involve multiple spatio-temporal scales. To understand the physical/chemical processes responsible for the faulting that earthquakes occur on, a multidisciplinary approach is highly recommended. Near Fault Observatories (NFOs) aim at providing high-precision and spatio-temporally dense multidisciplinary near fault data, enabling the generation of innovative scientific products.

The Alto Tiberina Near Fault Observatory (TABOO-NFO) is a permanent monitoring infrastructure around the Alto Tiberina Fault (ATF). The ATF is a 60 km long very low-angle normal fault (mean dip 20°) located along a 3 mm/yr extending sector of the Northern Apennines (Central Italy). The presence of repeating earthquakes on the ATF, as well as a steep gradient in crustal velocities measured by GNSS stations, suggest that portions of the ATF are creeping aseismically. Both laboratory and theoretical studies indicate that any given patch of a fault can creep, nucleate slow earthquakes, and host large earthquakes, as also documented in nature for some earthquakes (e.g., Iquique, Tohoku and Parkfield earthquakes). Nonetheless, how a fault patch switches from one mode of slip to another as well as the interaction between creep, slow and regular earthquakes are still poorly documented by near field observation.

TABOO is a state-of-the-art dense network, managed by the Istituto Nazionale di Geofisica e Vulcanologia (INGV), with mean inter-distance of about 5 km between multidisciplinary sensors, deployed both at surface and within shallow boreholes (<250m). Stations record and transmit in real time via dedicated Wi-Fi technology; then data is stored in standard formats on open access thematic portals and distributed via web services (http://fridge.ingv.it). With STAR, during the Fall of 2021 and Spring of 2022, INGV in collaboration with UNAVCO, drilled six 80-160 m deep boreholes surrounding the creeping portion of the ATF, to deploy Gladwin Tensor strainmeters and short period seismometers. Each “observatory” is also equipped with surface GNSS, meteorological instruments, and additional seismic sensors. The two deepest boreholes host fibre optic cables for temperature and strain. The strainmeter array (STAR) instruments are four-gauge strainmeters, from which we can resolve the horizontal strain matrix and measure deformation on the order of nanostrain, and bridge timescales encompassed neither by GNSS nor by Seismometers. With this new suite of instruments TABOO will enable the collection and calibration of strain records with exquisitely high precision, allowing for a quantitative characterization of ATF creep (~1 mm over <1 km2), enhanced monitoring of microseismicity (below Mc 0.5), and allowing correlation between degassing (CO2, Rn) measurements and subsurface strain.

Such unique near fault data Illuminating the spatiotemporal characteristics of creep on the ATF including possible stress triggering of larger earthquakes by transient creep events, are needed to address key questions of global importance in the seismic hazards and risk assessment community about the physics that allows for both seismic and aseismic slip on a single fault patch.

After presenting the field campaigns, we give an overview of the new data, showing how they enable us to detect new dynamic and static strain features missed by the other in situ instruments.

How to cite: Chiaraluce, L., Mencin, D., Bennett, R., Barchi, M. R., and Bohnhoff, M. and the STAR team: A strainmeter array to unravel the Alto Tiberina fault slip behaviour, Central Italy - ICDP STAR Drilling Project, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8462, https://doi.org/10.5194/egusphere-egu23-8462, 2023.

12:10–12:20
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EGU23-11373
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ECS
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On-site presentation
Marta Marchegiano, Marion Peral, Jeroen Venderickx, Koen Martens, Antonio García-Alix, Steven Goderis, and Philippe Claeys

Ostracod shells are small aquatic crustaceans (0.3 - 5 mm) capable of recording climatic and environmental changes at high-resolution in sedimentary archives of modern and ancient lakes. Their stable low-Mg calcite shell mineralogy makes them ideally suited for targeted geochemical analyses. Therefore, ostracods represent the best candidate to develop a new carbonate clumped isotope (∆47) lacustrine paleothermometer that disentangles and quantifies the effects of global climate changes at regional scale. To establish the relationship between 47 and the temperature for ostracod shells, three different species were collected in monitored environments at 4°C and 12°C and one was cultivated in the lab at 23°C. Our results show a linear regression between ostracod-47 and calcification temperature that is in agreement with previous published calibrations. This implies that ostracods are an equally-good recorder of (paleo)temperatures as other carbonaceous micro- or macrofossils from the marine realm. Moreover, we report the absence of a consistent offset between the species Eucypris virens and Bradleystrandesia fuscata coming from the same environment and precipitated at the same temperature. This observation suggests the absence of a vital effect at the genus and species level. Samples from shallow Lake Trasimeno (Italy) cover the last 50000 years and confirm the ability of the ostracod clumped-isotope thermometer as well as the absence of vital effect in the fossil record. The new paleothermometer identifies warmer/colder and humid/dryer conditions during Greenland Interstadial and Greenland Stadial/Heinrich events respectively.

These findings show that the ostracod-47 thermometer has several advantages that makes it an attractive tool for scientific drilling: (i) It is independent of ostracod species and geography. Hence, one can also use endemic species.  (ii) It is applicable throughout geological time, as extinct species can be used. (iii) Temperature reconstructions for all environments where ostracods live are within reach. We emphasize that also high-diversity lacustrine environments are suitable for 47 analysis, by mixing shells of different species together. This is of particular importance when working with small samples size from sediment cores.

The establishment of this new lacustrine proxy enables precise paleoclimatic reconstructions from different climate belts. It opens the door to new high-resolution continental paleoclimate and paleoenvironmental reconstructions and therefore has the potential to be a key tool in future lacustrine drilling in the ICDP framework.

How to cite: Marchegiano, M., Peral, M., Venderickx, J., Martens, K., García-Alix, A., Goderis, S., and Claeys, P.: The ostracod clumped-isotope thermometer: A new tool to quantify continental climate change., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11373, https://doi.org/10.5194/egusphere-egu23-11373, 2023.

12:20–12:30
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EGU23-13942
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On-site presentation
Katja Heeschen, Cindy Kunkel, Henning Lorenz, Vera B. Bender, Holger Kuhlmann, and Knut Behrends

The mobile Drilling Information System (mDIS) is ICDP’s (Internal Continental Scientific Drilling Program) database management software, initially designed for the acquisition of data gained during a drilling campaign. It is now in use for three years and is by far exceeding its intended application. MDIS has now been installed in core repositories with varying requirements and it is currently been tested for the use as a laboratory data collection application.

The system is based on 25 years of sample and data management at ICDP. It is a database backed web application that is entirely based on open-source code, is platform-independent and has a responsive design. Beyond the basic data registration and management, mDIS provides functionality for QR code label-printing, data export and report generation. Application specific XML export supports International Generic Sample Number (IGSN) registration and data visualization in the “Corelyzer” software (https://cse.umn.edu/csd/corelyzer). Third party software can interface the mDIS through its REST application programming interface (API). Version 3 of the mDIS software features an updated, consistent data model and n:m relations.

Driven by the pandemic, the “expedition mDIS” has mostly been installed as a SaaS (software as a service) variant hosted on a shared ICDP server rather than an offline virtual box application on a personal computer. This solution facilitates training and enhanced support by the ICDP-OSG, it provides continuity by the use of a single project database throughout the project lifespan, and it provides uncomplicated data access to scientists that are currently off-site. Next to the design of further print labels, reports and entry masks for borehole measurements, the most significant extension for the “expedition mDIS” is a digital visual core description allowing for printing a stratigraphic column while simultaneously filling the database. Inspired by a user, our next plan is to develop an add-on for managing sample requests in mDIS.

MDIS has now been implemented in several core repositories (“curation mDIS”), amongst them the Bremen Core Repository (BCR) of the International Ocean Discovery Program (IODP), were curators face up to several thousand samples a week during sample parties. The simultaneous input and processing of large amounts of data lead to new challenges in terms of data handling and database performance. The mDIS has been supplemented with modules to curate and store different sample types, to design and adapt sample series, to add a contact data base and adaptable reports. One of the most important add-ons is the so called “sample-sheet”, which facilitates fast data entry and automated printing of sample labels during large sampling parties.

For more information please visit the ICDP homepage (https://www.icdp-online.org/support/data-samples), the mDIS Documentation website (https://data.icdp-online.org/mdis-docs) or contact us directly. MDIS is open source and as such available for all projects and everybody who is interested.   

How to cite: Heeschen, K., Kunkel, C., Lorenz, H., Bender, V. B., Kuhlmann, H., and Behrends, K.: News on ICDP’s data management system mDIS: experiences, adaptions and extensions after three years of field application and core repository installation, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13942, https://doi.org/10.5194/egusphere-egu23-13942, 2023.

Lunch break
Chairpersons: Angelo Camerlenghi, Cindy Kunkel, Jorijntje Henderiks
14:00–14:10
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EGU23-16429
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On-site presentation
Dieter Rammlmair, Wilhelm Nikonow, and Simon Goldmann

The use of µEDXRF elemental mapping provides access to data on relatively large core sections within a reasonable time at high spatial resolution down to 20 µm, enabling to link macroscopic to microscopic information, and providing an objective tool to select areas of interest for more sophisticated data acquisition by EPMA, LA-ICP-MS etc. Textural features can be visualized, that hardly are identified with the naked eye e.g. interstitial silicates in massive chromitites of the Bushveld Complex, South Africa. The application of automated mineralogy provides access to local paragenetic changes and to modal analyses of selected areas. Automated mineralogy based on µEDXRF has to overcome a number of obstacles due to aspects of diffraction, depth of information and grain boundary effects. Tools have been developed to limit these aspects within an acceptable error frame by combining the information of two opposing detectors to reduce the side effects of diffraction. By applying a supervised endmember based classification using the spectral angle mapper algorithm of the ENVI hyperspectral software, phase distribution maps can be produced. Within a well-known system such as the UG-2 chromitite mineral names can be attributed to the identified phases. Exceptions exist for very fine grained secondary phases which might show mixed signals. Well-identified phases can be segmented and grain size, shape and orientation of individual grains can be obtained supported by diffraction signals of single grains. Chemical information can further be extracted for individual minerals, individual grains and bulk area corresponding to the modal mineralogy for any selected area. This offers a new approach to interprete (Verb fehlt?) complex textures by comparing chemical and mineralogical aspects of individual textural pattern. The example of mottled UG-2 chromite shows that the hosting silicates of the chromititebasically orthopyroxene and anorthite-rich plagioclase, but within stringers phlogopite, anorthite-poor plagioclase, potassic feldspar, amphibole, quartz with local enrichment of apatite and sulphides, show differences in grain size and chemistry of the chromite. EPMA investigations on chromite show that Cr/(Cr+Al), Mg/(Mg+Fe), and Cr/Fe is controlled by the chemistry of its hosting oikocryst silicates plagioclase or orthopyroxene. The appearance of late inter-oikocryst phlogopites induces a metasomatic loss of titanium in the chromite. By applying several steps of µEDXRF data reduction and phase masking, these changes in chromite chemistry can be visualized despite of the relatively large spot size of 20 µm for large areas. Using this information the metasomatic impact within a continuously µEDXRF mapped half drill core can be visualized and quantified. 

How to cite: Rammlmair, D., Nikonow, W., and Goldmann, S.: Highlighting the metasomatic impact on mottled UG-2 chromitites from the Bushveld Complex (South Africa)  by large-scale µEDXRF mapping., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16429, https://doi.org/10.5194/egusphere-egu23-16429, 2023.

14:10–14:20
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EGU23-12721
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Highlight
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Virtual presentation
Carolin Boese, Georg Dresen, Jochem Kück, Marco Bohnhoff, Ulrich Harms, Said Kamrani-Mehni, Günter Zimmermann, Ingo Sass, and Frank Holzförster

In 2023, the GEOREAL hydraulic stimulation experiment will be conducted at the KTB deep crustal lab in Windischeschenbach/Germany that originated from the Continental Deep Drilling Program of the Federal Republic of Germany (https://www.gfz-potsdam.de/ktb-tiefenlabor/). The two 4 and 9.1 km deep boreholes were drilled between 1987 and 1994, followed by a long-term experimental program between 1996 and 2005, providing key knowledge on in-situ geomechanical processes and the subsurface at the KTB site. This also led to the foundation of the International Continental Scientific Drilling Program (ICDP) in 1996.

GEOREAL aims at addressing research topics relevant for characterizing the geothermal potential of the metamorphic basement. The two KTB wells provide direct access to a petrothermal fluid reservoir at crustal depth and at temperatures ≥100°C at >3 km depth in the low-permeability rock, typical for large parts of the Earth's crust in Germany. These ambient pressure and temperature conditions are representative for a deep geothermal reservoir and have been extensively studied in the past. GEOREAL builds upon three major injection experiments between 1994 and 2005, during which 150–400 microearthquakes were located in close proximity to the stimulation intervals. The largest induced earthquake of M=1.2 occurred during the phase of highest flow rate. Most of the observed events had M∼0.

The GEOREAL hydraulic stimulation experiment aims at further refining the adaptive reservoir stimulation concept employing near-real-time microseismic monitoring with direct feedback on hydraulic parameters. It will include a series of hydraulic tests at depths ≥3.9 km to investigate the effect of pressure build-up and release, the role of continuous and periodically varying flow rates, the effect of relaxation phases and maximum injection pressure on the spatial propagation of induced earthquakes and the temporal evolution of their magnitudes. This procedure was successfully applied during the 2018 and 2020 geothermal stimulations in Helsinki, Finland. Using a double packer assembly, controlled injection in 15–20 m-long depth intervals, identified through logging will be performed. The goal of GEOREAL is to enhance hydraulic reservoir properties in the KTB pilot hole while avoiding noticeable seismic events. A unique seismic monitoring network will be set up with a 12-level geophone chain in the KTB main hole at only ~300 m distance to the stimulation interval to monitor the fluid injection with high precision. In addition, ≤40 seismometers will be installed surrounding the KTB, including several 45–150 m deep boreholes, and their data transmitted in real-time for rapid evaluation. With this setup, we expect a significantly higher number of locatable microearthquakes than observed during previous injection experiments at the KTB and thus more detailed information on the spatio-temporal propagation of the induced seismicity. A further goal of GEOREAL is to improve existing best practices for technical implementation and to reduce potential risks associated with the technology, thus improving the acceptance of deep geothermal energy in Germany.

How to cite: Boese, C., Dresen, G., Kück, J., Bohnhoff, M., Harms, U., Kamrani-Mehni, S., Zimmermann, G., Sass, I., and Holzförster, F.: GEOREAL: An adaptive stimulation experiment at 3.9 km depth at the KTB deep crustal lab, Germany, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12721, https://doi.org/10.5194/egusphere-egu23-12721, 2023.

14:20–14:30
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EGU23-7958
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Highlight
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On-site presentation
Yan Lavallée, Anette Mortensen, Paolo Papale, John Eichelberger, Freysteinn Sigmundsson, Ben Kennedy, Marlène Villeneuve, Philippe Jousset, Donald Bruce Dingwell, Sigurdur Markusson, Vordís Eiríksdóttir, Bjarni Pálsson, Jeff Tester, Sigrún Nanna Karlsdóttir, John Midgley, Hjalti Páll Ingolfsson, and John Ludden

Driven by the need to understand magmatic systems, to improve volcano monitoring strategy, and to develop next-generation, high-enthalpy, geothermal energy, we introduce the Krafla Magma Testbed (KMT) – located in Northeast Iceland. KMT aims to establish the first magma observatory – an international, open access, scientific platform to advance ductile zone to magma research via drilling and novel sensor systems. This frontier undertaking will enable direct, in situ sampling, instrumentation and manipulation, and monitoring of magma and its interface with solid Earth’s crust, vastly advancing models of high-temperature crustal processes. 

This initiative is enabled by past geothermal drilling at Krafla volcano that was serendipitously intersected and thus determined the exact location of magma for the first time. This unprecedented experience, including safe control of the wells, provides the basis for KMT, which stands to transform modern volcanology and geothermic disciplines. 

KMT will develop a long-term infrastructure (>25 years) for the conduct of interdisciplinary scientific, engineering, technological, and educational activities. The Krafla volcano has the advantage of a long history of geological study, volcano monitoring, and drilling as well as supporting surface facilities combining to produce the safest and most efficient base from which to explore Earth beyond the solidus.  

KMT will be the place to develop (1) our science of hot and molten Earth; (2) new ways of understanding and monitoring volcanoes; (3) our ability to extract and exploit geothermal energy sources; and (4) new technology and materials that function in the most extreme conditions in planetary systems. 

The value of potential gains in fundamental understanding of crustal processes is beyond our possibility to estimate. There is the prospect of an order of magnitude gain in geothermal energy productivity. The need to improve understanding of the source of catastrophic eruptions and to better forecast them is a compelling humanitarian one.

How to cite: Lavallée, Y., Mortensen, A., Papale, P., Eichelberger, J., Sigmundsson, F., Kennedy, B., Villeneuve, M., Jousset, P., Dingwell, D. B., Markusson, S., Eiríksdóttir, V., Pálsson, B., Tester, J., Karlsdóttir, S. N., Midgley, J., Ingolfsson, H. P., and Ludden, J.: Implementing the Krafla Magma Testbed (KMT): linking volcanology and geothermal research for future hazard and energy solutions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7958, https://doi.org/10.5194/egusphere-egu23-7958, 2023.

14:30–14:40
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EGU23-11822
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ECS
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On-site presentation
Mathias Vinnepand, Christian Zeeden, Anders Noren, Stefanie Kaboth-Bahr, William Gosling, Jochem Kück, and Thomas Wonik

Lake Bosumtwi was created after a meteorite impact 1.07 Ma ago in an area that is highly susceptible for climate changes due to shifts of the tropical rain belt, as well as variation in dust dynamics. The sedimentary sequence records such changes in the tension field between the North African Monsoon (humid, wet) and the Harmattan (dry and dusty winds from the Sahara) and has been intensively studied. Drilling in 2004, supported by the International Continental Scientific Drilling Program (ICDP), recovered downhole logging data and sediment cores that allow for the analysis of the complete ~300 m lacustrine sequence. Yet, detailed climatic and environmental reconstructions for the record have not been completed, mostly due to the absence of a robust age model beyond 500 ka. In 2022, we obtained core scanning natural gamma ray data of the ~300 m lacustrine sedimentary sequence. Based on this data, we are generating an astronomical age model that can be directly compared to the independently dated sections, but extends farther back in time. Our age model will provide critical chronologic context for the numerous existing and new proxy data that illuminate past changes in climate, environment, and ecosystems. This breakthrough will allow a robust framework to analyse climatic interferences with archaeological findings that might shed new light on habitat availability for our ancestors in tropical Western Africa.

 

How to cite: Vinnepand, M., Zeeden, C., Noren, A., Kaboth-Bahr, S., Gosling, W., Kück, J., and Wonik, T.: Extending the age model for Lake Bosumtwi (Ghana) to reconstruct West African climate and dust dynamics during the last million years, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11822, https://doi.org/10.5194/egusphere-egu23-11822, 2023.

14:40–14:50
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EGU23-17472
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On-site presentation
Arne Ulfers, Christian Zeeden, Stefanie Kaboth-Bahr, Thomas Westerhold, and Ursula Röhl

The characteristics of half-precession (HP) cycles (~9,000 - 12,000 years) are still poorly understood, despite their appearance in numerous records. Previous studies on European terrestrial and marine records indicate a connection of the HP-signal to low latitudes. Here, we investigate HP-cycles in equatorial regions to study the assumed origin of this signal.

Spectral analysis, evolutive approaches and correlation techniques are used on records from ODP Sites 662 and 663 to identify the HP-signal in elemental ratios reflecting e.g. terrigenuous input and/or bioproductivity. Filters have been designed to remove the classical orbital cycles (eccentricity, obliquity, precession), in order to isolate the HP-signal and to determine the temporal evolution of its presence and amplitude.

We present first results of a larger project which has the overall objective to characterize the HP-signal across the Mid-Pleistocene Transition (MPT) at Sites 662 and 663. Over the course of the MPT, the ~100 kyr-eccentricity cycles supersede the 41-kyr obliquity as the primary driver of climate forcing. As precession is modulated by eccentricity, a similar relationship may be assumed for HP and eccentricity. Our preliminary analyses show an enhanced HP-signal in the younger, 100-kyr eccentricity world, but also in the late MPT which is partly influenced by the 41-kyr obliquity cycle. Cyclostratigraphic investigations of high-resolution XRF data will provide a clearer insight into the presence, amplitude and role of HP during the MPT and the late Pleistocene.

How to cite: Ulfers, A., Zeeden, C., Kaboth-Bahr, S., Westerhold, T., and Röhl, U.: Cyclostratigraphic investigations with special emphasis on half-precession signals using XRF-data from ODP Site 663 (Eastern Equatorial Atlantic), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17472, https://doi.org/10.5194/egusphere-egu23-17472, 2023.

14:50–15:00
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EGU23-2476
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On-site presentation
Paul Olsen, Dennis Kent, Christopher Lepre, Sean Kinney, Abhishek RoyChowdhury, Clara Chang, David Tibbetts, and Chase Bebo

The age of the ~100 km Manicouagan impact structure (Quebec, Canada) is ~215.5 Ma (1, 2), falling roughly in the middle of the Norian (228-206 Ma) of the Late Triassic, plausibly corresponding to the mid-Norian biotic crisis in the oceans (3) and Adamanian-Revueltian (4) biotic turnover on land. The latter is the largest apparent biotic disruption in the continental Triassic of North America, as documented in the Chinle Formation of the Colorado Plateau and environs in the southwestern USA. Funded by ICDP and NSF (2013-2016), CPCP-1 cored nearly the entire Norian part of the Chinle intersecting what should be the time of the giant impact and biotic transition. Analyses of detrital CA-ID-TIMS U-Pb zircon ages and magnetostratigraphy resulted in two alternative age models for the Chinle in the core (5, 6). Model A emphasized the one-to-one magnetostratigraphic match of polarity zones between the Chinle (5) and the Newark-Hartford Astrochronostratigraphic Polarity Time Scale (N-H APTS) (7) and is consisent with the youngest zircon ages, whereas Model B emphasized the mean of the youngest coherent cluster of ages at a specific level (6). Although both age models agree for the upper stratigraphic core section of the Chinle, they differ dramatically lower down with Model B having three additional accumulation rate segments, one of which is so low as to suggest a hiatus at the Adamanian-Revueltian turnover and Manicouagan impact, similar to a  previous CA-ID-TIMS outcrop study (8). Model A predicts no discernable change in rate or hiatus at the putative event level and only one other accumulation rate segment. Timeseries analysis using Model A reveals significant ~1.8 Myr and 405 kyr cycles in both accumulation rate segments for natural gamma radiation and the elemental XRF ratios, in phase in both segments with the chaotic Mars-Earth and metronomic Venus-Jupiter cycles in the N-H APTS (9). Model B, in contrast, lacks significant cycles at these periods for the lower three accumulation rate segments. Consilience between Model A and the independent astrochronological predictions suggests it is the better model. The discrepancy with Model B is parsimoniously explained by the youngest coherent age clusters tending to be dominated by recycled zircons in the lower part of the core as suggested by LA-ICP-MS data (10). The Adamanian-Revueltian biotic turnover and Manicouagan impact therefore should have a record in the higher accumulation rate part of the Chinle and not be cut out by a hiatus or in a condensed section. Additional coring and denser CA-ID-TIMS ages will be needed to fully test the robustness of this conclusion.

1, Ramezani+ (2005) Geochim, Cosmochim. Acta 69:321. 2, Jaret+ (2018) EPSL 501:78. 3, Onoue+ (2016) Sci. Repts. 6:29609. 4, Parker & Martz (2011) EESTSE 101:231. 5, Kent+ (2019) Geochem. Geophys. Geosyst. 20:4654. 6, Rasmussen+ (2021) GSA Bull. 133:539. 7, Kent+ (2017) Earth-Sci. Rev. 166:153. 8, Ramezani+ (2014) AJS  314:981. 9, Olsen+ (2019) PNAS 116:10664. 10, Gehrels+ (2020) Geochronology 2:257.

How to cite: Olsen, P., Kent, D., Lepre, C., Kinney, S., RoyChowdhury, A., Chang, C., Tibbetts, D., and Bebo, C.: Searching for Manicouagan: astrochronological predictions and tests of alternative age models in the Late Triassic Chinle Formation [Colorado Plateau Coring Project-1 (CPCP-1), Arizona, USA] , EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2476, https://doi.org/10.5194/egusphere-egu23-2476, 2023.

15:00–15:10
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EGU23-4098
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On-site presentation
Yuki Morono, Andreas Teske, Diana Bojanova, Virginia Edgcomb, Nicolette Meyer, Florian Schubert, Laurent Toffin, and Christophe Galerne and the IODP Expedition 385 Scientists

Guaymas Basin is a young marginal rift basin in the Gulf of California characterized by active seafloor spreading and rapid sediment deposition, including organic-rich sediments derived from highly productive overlying waters and terrigenous sediments from nearby continental margins. The combination of active seafloor spreading and rapid sedimentation within a narrow basin results in a dynamic environment where linked physical, chemical, and biological processes regulate the cycling of sedimentary carbon and other elements.

During IODP Expedition 385, eight sites were drilled on the flanking regions and in the northern axial graben of Guaymas Basin, recovering organic-rich sediments with sill intrusions. Those cored samples were examined for their microbial cell abundance in a highly sensitive manner by density-gradient cell separation at the super clean room of Kochi Core Center, Japan, followed by direct counting on fluorescence microscopy. Cell abundance in surficial seafloor sediment (~109 cells/cm3) was roughly 1000 times higher than the bottom seawater (~106 cells/cm3) and gradually decreased with increasing depth and temperature. In contrast to the cell abundance profile observed at Nankai Trough (IODP Exp. 370), the gradual decrease of cell abundance was observed up to around 75ºC, and we detected microbial cells even at hot horizons above 100ºC. The existence of smaller size of microbial cells was uniquely found in this region of subseafloor.

We will present the overview of the microbial cell distribution in the Guaymas Basin and discuss its relation to the current and past environmental conditions, e.g., temperature and sill-intrusion, etc.

How to cite: Morono, Y., Teske, A., Bojanova, D., Edgcomb, V., Meyer, N., Schubert, F., Toffin, L., and Galerne, C. and the IODP Expedition 385 Scientists: Microbial cell distribution in the Guaymas Basin subseafloor biosphere, a young marginal rift basin with rich organics and steep temperature gradient, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4098, https://doi.org/10.5194/egusphere-egu23-4098, 2023.

15:10–15:20
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EGU23-10581
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On-site presentation
Understanding the patterns of microbial diversity across the seismogenic zones of Koyna (India) and South African gold mine through scientific drilling
(withdrawn)
Pinaki Sar, Rajendra Sahoo, Tullis Onstott, Thomas Kieft, Thomas Wiersberg, Hiroshi Ogasawara, Sufia Kazy, and Sukanta Roy
15:20–15:30
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EGU23-12625
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On-site presentation
Exploring the diversity, distribution and metabolic potential of chemolithotrophic and chemoorganotrophic microorganisms reactivated from deep continental granitic crust beneath the Deccan Traps, India
(withdrawn)
Sufia Kazy, Sunanda Mandal, Himadri Bose, Kheerthana Ramesh, Rajendra Sahu, and Pinaki Sar
15:30–15:40
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EGU23-9523
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Highlight
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On-site presentation
Catherine Rose, Tony Prave, Iona Baillie, Marjorie Cantine, Simone Kasemann, Francis Macdonald, Melanie Mesli, Andreas Nduutepo, Sara Pruss, Ricardo Trindade, and Maoyan Zhu

The Neoproterozoic Era (1000 - 541 Ma) is one of the most dramatic in Earth history: metazoans evolved, the supercontinent Rodinia formed and broke apart, the global carbon cycle underwent high-amplitude fluctuations, oxygen concentrations rose and climate experienced at least two episodes of worldwide glaciation. However, the discontinuous and fragmented nature of outcrop-based studies has hindered developing quantitative models of Earth system functioning during that Era. The Geological Research through Integrated Neoproterozoic Drilling (GRIND) project begins to rectify this scientific shortcoming by obtaining 13 cores through the archetype successions that record this environmental and biogeochemical change.

 

The specific targets are the Ediacaran-Cambrian transition (ECT; c. 560-530 Ma) in south Namibia (Nama Group), strata of west Brazil (Corumbá Group), and South China (Doushantuo, Dengying and equivalent formations). Drilling in Namibia and Brazil is complete, and drilling in China will commence in 2023. The work aims to 1) construct a highly resolved temporal framework that will lead to the development of age models for the ECT; 2) refine the patterns of biotic evolution of organic-walled and mineralised microfossils, metazoans and trace fossils, and identify the links between and test hypotheses about biological evolution and environmental change, and 3) using fresh, unweathered samples, determine the palaeoenvironmental and biogeochemical conditions that led to the rise of oxygen and distinguish cause-and-effect relationships and basin-specific versus global-scale secular trends in geochemical and stable isotope patterns.

 

We present sedimentological data from the characterised split cores from Namibia and Brazil, which are permanently archived at an in-country repository as well as the Federal Institute for Geosciences and Natural Resources in Germany. All cores will be available for future research, education and national capacity building activities and mark the first step towards creating an on-shore core archive that will match in stature that of the IODP.

How to cite: Rose, C., Prave, T., Baillie, I., Cantine, M., Kasemann, S., Macdonald, F., Mesli, M., Nduutepo, A., Pruss, S., Trindade, R., and Zhu, M.: Grinding through the Ediacaran-Cambrian Transition, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9523, https://doi.org/10.5194/egusphere-egu23-9523, 2023.

Coffee break
Chairpersons: Cindy Kunkel, Harue Masuda, Thomas Wiersberg
16:15–16:25
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EGU23-17266
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solicited
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Highlight
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On-site presentation
Christoph Heubeck and Nic Beukes

Units of the up to 3.7 km thick Moodies Group (~3.22 Ga) in the Barberton Greenstone Belt, South Africa and Eswatini, comprise some of the oldest well-preserved sedimentary strata on Earth, deposited within only a few million years in pro-deltaic to alluvial settings, with a dominance of tidal deltas and coastal plains. They consist of widespread quartzose, lithic, tuffaceous and arkosic sandstones, polymict conglomerates, common siltstones and shales, and rare BIFs and jaspilites, all interbedded with rare dacitic air-fall tuffs and several lavas. Moodies strata preserve abundant sedimentary structures and represent a very-high-resolution record of Paleoarchean surface processes. Microbial mats, early diagenetic vadose-alteration zones and tidal rhythmites are locally common. Moodies strata provide a unique opportunity to investigate the conditions under which bacterial life spread and thrived in coastal-zone and terrestrial settings on early Earth.

The ICDP Barberton Archean Surface Environments (BASE) Project drilled November 2021 to July 2022 eight inclined boreholes of 280 to 497 m length each through steeply inclined or overturned Moodies Group strata. The unweathered and continuous core record was complemented by sampling in three several-km-long tunnels and by detailed surface mapping. Two to three rigs operated concurrently, delivering twenty to sixty m of high-quality core daily. This core was processed in a large, publicly accessible hall in downtown Barberton. An exhibition provided background explanations for visitors and related this fundamental-geoscience research project to the geology of the Barberton-Makhonjwa Mountains World Heritage Site. The archive half of the core, nearly 3 km total, remained in South Africa, the working half is curated at the ICDP core repository in Berlin, Germany. We show preliminary cross sections, overall core photographs and representative lithologic descriptions.

How to cite: Heubeck, C. and Beukes, N.: Geologic framework and first results from ICDP BASE drilling in the Moodies Group (~3.22 Ga), Barberton Greenstone Belt, South Africa, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17266, https://doi.org/10.5194/egusphere-egu23-17266, 2023.

16:25–16:35
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EGU23-6477
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On-site presentation
Edoardo Dallanave, Rupert Sutherland, Gerald Dickens, Liao Chang, Evdokia Tema, Laia Alegret, Claudia Agnini, Thomas Westerhold, Cherry Newsam, Adriane Lam, Wanda Stratford, Julien Collot, Samuel Etienne, and Tilo von Dobeneck

Northern Zealandia is a continent submerged for more than 90% under the water of the southwest Pacific Ocean and separated from Australia by the Tasman Sea ocean basin. Its absolute position since its drift form Australia in the Cretaceous is determined by means of global absolute plate motion models, as local paleomagnetic constraints are completely missing. We present new absolute paleolatitudes for northern Zealandia using paleomagnetic data from sediments drilled in International Ocean Discovery Program Sites U1507 and U1511 (Expedition 3711,2). After correcting for paleomagnetic inclination shallowing, typical of sediments, we derived five paleolatitude estimates that provide a trajectory of northern Zealandia past position from the middle Eocene to early Miocene, spanning geomagnetic polarity chrons C21n to C5Er (~48–18 Ma). Generally, our results support previous works on global absolute plate motion, including a rapid 6° northward migration of northern Zealandia between the early Oligocene–early Miocene. However, paleomagnetic-determined absolute paleolatitude is systematically lower, and this difference is significant in the Bartonian and Priabonian (C18n–C13r). This discrepancy may be explained by some degree of true polar wander, a solid Earth rotation with respect to the spin axis that can be resolved only using paleomagnetic data. These new paleomagnetic dataset anchors past latitudes of Zealandia to Earth’s spin axis, with implications not only for global geodynamics, but for addressing paleoceanographic problems, which generally require precise paleolatitude placement of proxy data3.

Figure 1. Present-day map of northern and southern Zealandia, enveloped respectively by the yellow and orange dashed line. The yellow stars indicate the location of International Ocean Discovery Program Sites U1507 (26.4886°S, 166.5286°E) and U1511 (37.5611°S, 160.3156°E). Solid and dashed white lines indicate active and inactive subduction zones, respectively, with arrows lying on the overriding plate. LHR = Lord Howe Rise, NCT = New Caledonia trough, NR = Norfolk Ridge, RB = Reinga basin.

(1) Sutherland, R. et al. Proc. Int. Ocean Discov. Progr. 371, 1–33 (2019); (2) Dallanave, E. & Chang, L. Newsletters Stratigr. 53, 365–387 (2020); (3) Dallanave, E. et al. J. Geophys. Res. Solid Earth 127, 1–19 (2022).

How to cite: Dallanave, E., Sutherland, R., Dickens, G., Chang, L., Tema, E., Alegret, L., Agnini, C., Westerhold, T., Newsam, C., Lam, A., Stratford, W., Collot, J., Etienne, S., and von Dobeneck, T.: Middle Eocene to the early Miocene northward migration of northern Zealandia determined from the sedimentary record of IODP Exp. 371 (Tasman Sea), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6477, https://doi.org/10.5194/egusphere-egu23-6477, 2023.

16:35–16:45
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EGU23-1375
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On-site presentation
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Henk Brinkhuis, Francesca Sangiorgi, Evi Wubben, and Matt O'Regan

Some fifteen years ago, the pioneering Arctic IODP Expedition 302 (ACEX) drilled, and partly recovered Cenozoic sedimentary successions at the Lomonosov Ridge (LR) close to the North Pole. Of the few intervals recovered, one was regarded to likely encompass the Paleogene-Neogene (P/N) transition. On board and follow up marine palynological (mainly dinoflagellate cyst) studies indicate that within this P/N section, a hiatus lasting ~ 25 Myr likely separates the top of the recovered Paleogene (dated ~44 Ma, mid Eocene) from the locally recovered base of the Neogene (likely dated ~18 Ma, mid Early Miocene).

 

The hiatus is represented by the boundary between local lithological subunits 1/6 and 1/5. Unit 1/5 is informally often referred to as the “Zebra unit”, owing to its characteristic (cross bedded) black/white colored alternations of silty clays. Palynological and elemental and organic geochemical studies of subunits 1/6 and 1/5 supported the inference of a major hiatus, as the proxies show a sharp change at the subunit boundary, although the reconstructed paleoenvironments of both subunits indicate marginal marine, restricted conditions. This aspect on its own already represents a challenge for geophysical models, which placed the LR at deeper waters at the P/N boundary. A key finding in the “Zebra unit” is a massive occurrence of representatives of a – back then - unknown dinoflagellate cyst genus, later formally described as Arcticacysta. Because of its morphology, akin to typical Neogene dinocyst taxa, it was postulated that the Zebra interval was early Neogene in age, confirming the existence of a major hiatus. However, successive Rhenium‐Osmium (Re‐Os) isochron ages and complementary Os‐isotope measurements from subunits 1/6 and 1/5 led to postulate that the P/N transition was in essence complete, albeit extremely condensed. This data hence challenged the presence of a major hiatus and depicted a very different geological evolution of the LR.

 

Here we introduce new findings from the lower to mid-Miocene sediments retrieved from the Pennell Basin during IODP Expedition 374 (Ross Sea, Antarctica) in 2018. These now constitute the second known record containing specimens of Arcticacysta. Importantly, these findings now confirm the initial age assignment of the Arctic “Zebra Unit” to the early Miocene and provide decisive evidence for a large hiatus characterizing the P/N transition on the central Lomonosov Ridge. An important corollary is that the central Lomonosov Ridge was likely subaerial or ultra-shallow marine by the end of Oligocene, leading to a totally new perspective of its Cenozoic history.

How to cite: Brinkhuis, H., Sangiorgi, F., Wubben, E., and O'Regan, M.: IODP 302: Dating 'Zebra'; was the Lomonosov Ridge a central Arctic Ocean Island in the Oligocene?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1375, https://doi.org/10.5194/egusphere-egu23-1375, 2023.

16:45–16:55
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EGU23-14109
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On-site presentation
Paul Knutz, Lara Perez, and Tove Nielsen

The need for constraining future climate scenarios requires a better understanding of how the cryosphere responded to ocean-climate conditions that were warmer than present. The Greenland shelf margins store thick sedimentary packages that may offer detailed information pertaining to ice-ocean-climate dynamics and Arctic ecosystems. A wealth of seismic data acquired since the early nineties has generated numerous subsurface maps and geomorphic studies of expanded sedimentary archives located proximal to the Greenland Ice Sheet. While paleoclimate reconstructions of ice sheet and ocean dynamics have largely been based on North Atlantic deep-water records, the Greenland continental margin will be the focus of forthcoming International Ocean Discovery Program missions such as Exp. 400, NW Greenland margin. The aim of this presentation is to provide an update of the late Cenozoic marine successions that form key targets for understanding cryospheric behavior during warm climate periods, in particular the Miocene-Pliocene interval characterized by contourite drifts and hemipelagic sequences. The significance for pushing knowledge frontiers on Northern Hemisphere climate evolution and Earth System modelling will be discussed. 

How to cite: Knutz, P., Perez, L., and Nielsen, T.: Late Cenozoic sedimentary systems offshore West Greenland providing new insights to ice-ocean interactions during periods of enhanced climate warming, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14109, https://doi.org/10.5194/egusphere-egu23-14109, 2023.

16:55–17:05
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EGU23-5797
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ECS
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On-site presentation
Arianna Valentina Del Gaudio, Werner E. Piller, Gerald Auer, and Walter Kurz

The Mariana forearc constitutes the southern sector of the Izu-Bonin-Mariana (IBM) trench-arc system (12° N to 35° N) in the NW Pacific Ocean. It is the only setting where active serpentinite mud volcanism is recorded.

The Mariana forearc hosts several large serpentinite mud volcanoes, among which Fantangisña seamount was cored during International Ocean Discovery Program (IODP) Expedition 366. Lithologies comprise pelagic sediments covering serpentinite mud deposits with ultramafic clasts which derive from the subducting Pacific Plate, forearc crust and mantle. In addition, nannofossil-bearing pelagic sediments and volcanic ash/tephra layers were found at the bottom of the core.

Fantangisña seamount is located in the tropical Pacific region, at low latitudes (16° N) within the latitudinal band of the North Equatorial Current (NEC). The NEC is a warm and nutrient- poor water mass, flowing westward in the tropical Pacific Ocean, driven by trade winds.

In this study, benthic and planktonic foraminifera analyses were performed at Site U1498A, located on the southern flank of Fantangisña serpentinite mud volcano. Most of our analysed interval covers the Early to Late Pleistocene as indicated by previous biostratigraphic investigation on this site. Cluster analyses on Pleistocene planktonic foraminifera resulted in two major clusters based on thermocline-dwelling species (e.g., Globorotalia spp.) to mixed-layer dwellers (e.g., G. ruber, G. rubescens, G. glutinata, Trilobatus spp.) ratio, which infer variations of the depth of the thermocline (DOT) during the Pleistocene. These changes of the DOT can be related to fluctuations in the intensity of the NEC. Our data implies a deep and stable thermocline with an intense NEC during the interval of the Early-Middle Pleistocene Transition (EMPT). In contrast, both thermocline and NEC weakened during the Middle-Late Pleistocene, following the EMPT. Variations in strength of the NEC could be associated with ENSO climate conditions (El Niño/La Niña).

Planktonic foraminifera diversity suggests that the distribution of planktonic assemblages was not affected by the serpentinite mud activity in the area. In addition, our results imply that the preservation of the planktonic tests could be enhanced by rapid burial under the serpentinite mud flows.

High diversity (99 taxa) was recorded for benthic foraminifera before and after the serpentinite mud flow volcanism indicating oligotrophic and well-oxygenated bottom-water conditions. In contrast, benthic species were severely affected by the volcanic activity due to serpentinite mud flows and gas emissions.

 

How to cite: Del Gaudio, A. V., Piller, W. E., Auer, G., and Kurz, W.: Planktonic and benthic foraminifera assemblages from Fantangisña serpentinite mud volcano in the NW Pacific Ocean during the Pleistocene (IODP Expedition 366), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5797, https://doi.org/10.5194/egusphere-egu23-5797, 2023.

17:05–17:15
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EGU23-16019
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Virtual presentation
David Hodell, Abrantes Fatima, and Zarikian Carlos and the IODP Expedition 397 Scientists

The Iberian margin is a well-known source of rapidly accumulating sediment that preserves a high-fidelity record of millennial climate variability. Previous studies of piston cores and IODP Site U1385 demonstrated that surface, and deep-water climate signals from the region can be correlated precisely to the polar ice cores in both hemispheres and with European terrestrial sequences. The continuity, high sedimentation rates, and fidelity of the climate signals recorded in Iberian margin sediments make this region a prime target for ocean drilling. The primary objective of IODP Expedition 397 was to extend these remarkable paleoclimate records beyond the range of existing piston and IODP cores -- currently limited to the last 1.5 million years. To this end, we recovered a total of 6176.7 m of core at four sites (U1586, U1587, U1385, and U1588) arranged along a bathymetric transect (4691, 3479, 2590 and 1339 mbsl, respectively) to intersect each of the major subsurface water masses of the eastern North Atlantic. The bathymetric transect provides an opportunity to study the history of deep-water circulation, ventilation and carbon storage in the deep eastern North Atlantic and its relationship to changing atmospheric CO2. Sediments from all sites display strong cyclicity in bulk sediment properties, permitting the development of orbitally-tuned time scales and correlation with classic Mediterranean cyclostratigraphy. We will report on existing results from Site U1385 drilled during Expedition 339, new preliminary results from Expedition 397 sites (including the reoccupation of Site U1385), and discuss the future potential of Iberian margin sediments for providing benchmark paleoclimate records for the late Miocene through Quaternary. 

How to cite: Hodell, D., Fatima, A., and Carlos, Z. and the IODP Expedition 397 Scientists: Benchmark sedimentary records recovered from the Iberian margin during IODP Expedition 397 , EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16019, https://doi.org/10.5194/egusphere-egu23-16019, 2023.

17:15–17:25
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EGU23-2139
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Highlight
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On-site presentation
Gilbert Camoin, Edouard Bard, Pierre Deschamps, Marc Humblet, Juan Carlos Braga, Abel Guilhou, Nadine Hallmann, Jennifer Weil-Accardo, Yoann Fagault, and Bruno Hamelin

Coral reef records related to past higher and/or rising sea levels provide an important baseline for developing projections regarding the response of modern coastal systems to future sea-level rise. Sea-level rise at the end of the current century is expected to range between 5.5 and 10 mm. yr-1 on average, depending on the various scenarios of  global warming [IPCC, 2019]. The Last Deglaciation (23 to 6 kyr B.P.) is seen as a potential recent analogue of the environmental changes that the Earth may face in the near future as a consequence of ocean thermal expansion and the melting of polar ice sheets. The last deglacial record from Barbados suggests a non-monotonous sea-level rise averaging 10 mm.yr-1 and punctuated by two ‘meltwater pulses’ (MWP) characterized by several centuries of extremely rapid sea-level rise related to catastrophic ice-sheet collapse [Fairbanks, 1989, Nature, 342, 637; Bard et al., 1990, Nature, 346, 456; Peltier & Fairbanks, 2006, Quat. Sci. Rev., 25, 3322].

IODP Expedition 310 ‘Tahiti Sea Level’ and land drilling on the modern barrier reef of Papeete have provided unparalleled coral reef records encompassing the period covered by the two MWP identified previously in Barbados. Reefs accreted continuously between 16 and 10 kyr B.P. in Tahiti, mostly through aggradational processes, at growth rates averaging 10 mm yr–1. Changes in the composition of coralgal assemblages coincide with abrupt variations in reef growth rates and characterize the response of the upward-growing reef pile to non-monotonous sea-level rise and coeval environmental changes [Camoin et al., 2012; Geology, 40, 643; Camoin & Webster, 2015; Sedimentology, 62, 401].

While the MWP-1B at approximately 11.3 kyr B.P. in Barbados is absent or very small in Tahiti [Bard et al. 1996; Nature, 382, 241; Bard et al., 2010; Science, 327, 1235; Bard et al., 2016; Paleoceanography, 31], the Tahiti offshore record has provided the opportunity to document the MWP-1A at several drill sites. A sea-level rise of 16±2 m in amplitude has been evidenced between 14.65 and 14.3 kyr B.P., coeval with the Bølling warming [Deschamps et al., 2012, Nature, 483, 559]. The rate of eustatic sea-level rise ranged from 40 to 50 mm.yr-1 during MWP-1A, implying that this episode corresponds to one of the fastest rises in sea level ever documented in Earth history.

This paper documents in unprecedented detail the reef response to extreme sea-level rise during MWP-1A in Tahiti. It is based on new accurate U-series and 14C AMS ages of corals and algae and the reappraisal of the environmental significance and paleowater depth interpretation of various coralgal assemblages. The succession in time and space of successive reef assemblages involved in reef accretion during the MWP-1A leads, for the first time, to reconstruct reef accretion patterns during this dramatic period, which is of prime importance to help forecasting coral reef response to future sea-level change.

How to cite: Camoin, G., Bard, E., Deschamps, P., Humblet, M., Braga, J. C., Guilhou, A., Hallmann, N., Weil-Accardo, J., Fagault, Y., and Hamelin, B.: CORAL REEF RESPONSE TO EXTREME SEA-LEVEL CHANGE: THE MELTWATER PULSE 1A (14.65 ka and 14.3 ka BP). IODP EXPEDITION #310 ‘TAHITI SEA LEVEL’, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2139, https://doi.org/10.5194/egusphere-egu23-2139, 2023.

17:25–17:35
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EGU23-3744
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Virtual presentation
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Yin Lu, Ed Pope, Jasper Moernaut, Revital Bookman, Nicolas Waldmann, Amotz Agnon, Shmuel Marco, and Michael Strasser

Sediment density flows (ρflow<ρwater, overflows: flood plumes; ρflow>ρwater, underflows: including turbidity currents and debris flows) are major processes for transporting sediments and organic carbon from rivers, coasts or continental shelves into deep basins. These flows can also have serious socioeconomic consequences such as breaking seabed communications cables and pipelines. Given the potential impacts of climate change, it is important to quantify how sediment density flow processes are impacted by changing environmental conditions.

Lab-simulations and/or field monitoring campaigns on the timescales of seconds to years are helpful for understanding specific triggers for sediment density flows and how their magnitude/frequency may change under different conditions. However, these methods cannot be applied to longer timescales, which are of great interest to geologists and palaeoclimatologists trying to understand the past. It is unclear whether, and if so how, long-term climate changes affect the magnitude/frequency or type of sediment density flows within a specific water body. One approach to answering this question is to analyze a comprehensive geological record that comprises deposits that can be reliably linked to modern sediment flow processes.

To address this question, we analyzed the unique ICDP Core 5017-1 from the Dead Sea (the largest and deepest hypersaline lake on Earth -- ρwater:1240 g/L) depocenter covering MIS 7-1. Based on an understanding of modern sediment density flow processes in the lake, we link homogeneous muds in the core to overflows (surface flood plumes, ρflow<ρwater), and link graded turbidites and debrites to underflows (ρflow>ρwater). Our dataset reveals (1) overflows are more prominent during interglacials, while underflows are more prominent during glacials; (2) orbital-scale climate changes affected the magnitude/frequency of the flows via changing salinity and density of lake brine and lake-level (Lu et al., 2022).

The current research bridges the gap between our understanding of modern sediment density flow processes and deposits preserved in a long-term geological record in the Dead Sea, a tectonically active subaqueous environment (Lu et al., 2020). It has wider implications for turbidite paleoseismology and implies that to develop prehistoric turbidites as a reliable paleoearthquake indicator, comprehensive modern sediment flow monitoring is essential. It also has wider implications for paleoclimate research in a tectonically active subaqueous environment. A sedimentary archive is filtered to remove significant instantaneous event deposits such as turbidites and debrites could help paleoclimatologists to better reconstruct paleoclimate change.

 

Refs.:

Lu, Y., Wetzler, N., Waldmann, N.D., Agnon, A., Biasi, G.P., and Marco, S., 2020. A 220,000-year-long continuous large earthquake record on a slow-slipping plate boundary. Science Advances, 6 (48), doi: 10.1126/sciadv.aba4170

Lu, Y., Pope E., Moernaut, J., Bookman, R., Waldmann, N., Agnon, A., Marco, S., Strasser, M., 2022. Stratigraphic record reveals contrasting roles of overflows and underflows over glacial cycles in a hypersaline lake (Dead Sea). Earth and Planetary Science Letters, 594, 117723, doi: 10.1016/j.epsl.2022.117723

How to cite: Lu, Y., Pope, E., Moernaut, J., Bookman, R., Waldmann, N., Agnon, A., Marco, S., and Strasser, M.: How do long-term climate changes affect the magnitude/frequency of sediment density flows? Insights from the Dead Sea ICDP drilling, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3744, https://doi.org/10.5194/egusphere-egu23-3744, 2023.

17:35–17:45
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EGU23-6170
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Highlight
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On-site presentation
Verena Foerster, Asfawossen Asrat, Christopher Bronk Ramsey, Erik T. Brown, Alan Deino, Matthew Grove, Annette Hahn, Annett Junginger, Stephanie Kaboth-Bahr, Christine S. Lane, Stephan Opitz, Anders Noren, Helen M. Roberts, Ralph Tiedemann, Ralf Vogelsang, Céline M. Vidal, Andrew S. Cohen, Henry F. Lamb, Frank Schaebitz, and Martin H. Trauth

As a contribution towards a regional environmental context of human-climate interactions, the ICDP co-funded Chew Bahir Drilling Project, a part of the HSPDP (Hominin Sites and Paleolakes Drilling Project), recovered ~280-m long cores of sedimentary strata through continental scientific drilling in southern Ethiopia. The fluvio-lacustrine coring locality in the Chew Bahir basin is situated near key archaeological and paleoanthropological sites, such as the Omo-Kibish where the Omo 1 and 2 Homo sapiens fossils were recovered.

Here we present the 620,000-year environmental record from Chew Bahir that provides an extraordinary opportunity to examine the potential influence of climate variability on hominin evolution, cultural innovation and dispersal during the Middle to Late Pleistocene. The near-continuous Chew Bahir record documents 13 environmental episodes that differ in length and character, potentially inducing habitat changes influencing hominin biological and cultural transformation. We infer that long-lasting and relatively stable humid conditions from ~620,000–275,000 years BP (Episodes 1–6) were interrupted by several abrupt and extreme hydroclimatic oscillations. This phase coincided with the appearance of high anatomical diversity in hominin groups. During Episodes 7–9 (~275,000–60,000 years BP), a pronounced pattern of climatic cyclicity was paralleled by the gradual transition from Acheulean to Middle Stone Age technologies, the emergence of H. sapiens in eastern Africa, and a key phase of human social and cultural innovation. Episodes 10–12 (~60,000–10,000 years BP), marked by high-frequency climate oscillations, is contemporaneous with the global dispersal of H. sapiens, facilitated by continued technological innovation and the alignment of humid pulses between eastern Africa and the eastern Mediterranean.

Prospectively, the Chew Bahir record represents a crucial component for the Middle and Late Pleistocene in the ongoing efforts of the scientific community (future and upcoming ICDP-funded projects) to address questions in Africa  across four topical core areas: paleoclimate, paleoenvironment, basin evolution, and modern lake systems.

How to cite: Foerster, V., Asrat, A., Bronk Ramsey, C., Brown, E. T., Deino, A., Grove, M., Hahn, A., Junginger, A., Kaboth-Bahr, S., Lane, C. S., Opitz, S., Noren, A., Roberts, H. M., Tiedemann, R., Vogelsang, R., Vidal, C. M., Cohen, A. S., Lamb, H. F., Schaebitz, F., and Trauth, M. H.: Pleistocene climatic variability in eastern Africa influenced hominin evolution: the 620,000-year climate record from Chew Bahir, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6170, https://doi.org/10.5194/egusphere-egu23-6170, 2023.

Introduction

Posters on site: Thu, 27 Apr, 08:30–10:15 | Hall X3

Chairpersons: Cindy Kunkel, Jorijntje Henderiks
X3.35
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EGU23-7814
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ECS
Tim van Peer, Andrew McIntyre, Marisa Rydzy, Erwan Le Ber, and European Petrophysics Consortium Team Members

The European Petrophysics Consortium (EPC) is part of the ECORD Science Operator (ESO). EPC comprises the University of Leicester and Géosciences Montpellier and provides petrophysics staff scientists and petrophysicists, as well as expertise in downhole logging and core petrophysics programmes. The EPC has dedicated equipment for core logging and discrete measurements and is involved in data calibration, quality control, evaluation and interpretation of these data. The EPC is also involved in post-expedition activities, the preparation of upcoming expeditions, capability development, and training for IODP MSP expeditions and other key activities, including education and training.

Over the past pandemic years, EPC has been active within expeditions and the community. EPC recognizes the importance of scientific drilling to palaeoclimate studies amongst other key topics, which is also reflected in our new science and operations roadmap: i) hired new staff members with a paleoclimate background; ii) developed a system for knowledge exchange between petrophysics and climate scientists, for instance via the ECORD summer schools; iii) renewed focus to include the development of measurement protocols and data analysis techniques to better serve the IODP community.

EPC also has a website (http://www.le.ac.uk/epc) and will host the next ECORD Summer School Downhole Logging for IODP Science in person in Leicester in summer 2023.

 

*European Petrophysics Consortium Team Members:

Sarah Davies, Simon Draper, Tim van Peer, Andrew McIntyre, Marisa Rydzy (University of Leicester).

Philippe Pezard, Johanna Lofi, Erwan Le Ber, Laurent Brun (University of Montpellier).

How to cite: van Peer, T., McIntyre, A., Rydzy, M., Le Ber, E., and Team Members, E. P. C.: European Petrophysics Consortium's Contributions to IODP, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7814, https://doi.org/10.5194/egusphere-egu23-7814, 2023.

X3.36
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EGU23-7956
Tim Freudenthal, Heinrich Villinger, Michael Riedel, and Thomas Pape

Borehole temperature measurements can be easily conducted  at the end of a drilling operation during trip out of the drill string (logging while tripping) without the need for additional operational time. After the final drilling depth was reached, an autonomous borehole logging tool including a temperature sensor is placed at the lower end of the drill string with the sensor part having passed the drill bit and sticking out in the open borehole between bottom of the borehole and drill bit. During trip out the logging tool is hooked up together with the drill string inside the borehole and measures the fluid temperature within the borehole. Stationary phases occur at regular intervals during disconnecting drill rods from the drill string. The analysis of the borehole temperatures during these stationary phases allow the investigation of changes of borehole temperatures with depth and with time. These temperature changes are a function of the geothermal gradient and the perturbation of the temperature field by the drilling action. Here we present results of a pilot study (Freudenthal et al., 2022) based on borehole temperature measurements acquired with the sea floor drill rig MARUM-MeBo200. By modeling the temperature evolution from the start of the drilling operation on, it is possible to analyze the impact of the drilling perturbation on the temperature field and to conclude on the regional heat flux.

 

References:

Freudenthal, T., Villinger, H., Riedel, M., and Pape, T. (2022) Heat flux estimation from borehole temperatures acquired during logging while tripping: a case study with the sea floor drill rig MARUM-MeBo. Marine Geophysical Research 43:37. doi: 10.1007/s11001-022-09500-1

How to cite: Freudenthal, T., Villinger, H., Riedel, M., and Pape, T.: Estimation of regional heat flux based on borehole temperatures acquired during logging while tripping with the sea floor drill rig MARUM-MeBo200, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7956, https://doi.org/10.5194/egusphere-egu23-7956, 2023.

X3.37
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EGU23-4430
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ECS
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Highlight
Elena Jovanovska, Jeffery Stone, Walter Salzburger, and Friedemann Schrenk

Adaptive radiation is considered to play an important role in the diversification of life on Earth. This is especially true in isolated long-term environments where the largest adaptive radiations have been found and where the adaptive nature of diversification has been best studied. However, the environmental conditions that influence rapid diversification during adaptive radiations and potentially lead to differences in evolutionary trajectories and species richness across the tree of life are still unclear, primarily because there few, if any, fossil records for some of the most iconic examples of vertebrate radiations. Here, we use two diverse groups of diatoms (Diploneis and Afrocymbella) with different lifestyles and great fossilization potential to test the role of environment in adaptive radiation and its impact on evolutionary trajectories between different diatom clades in East African Rift lakes that are home to the world's largest radiations – that of cichlid fishes. We constructed a time-calibrated molecular phylogeny of extant and extinct species, as well as a trait matrix, and show that the two diatom groups evolved within the rift from a common ancestor over a relatively short time, with accelerated diversification leading to much higher species richness in the genus Diploneis. We then correlate the inferred diversification rates and trajectories of trait evolution with biological and environmental variables to determine the influence of the environment on the progression of adaptive radiation. This integration of genetic, morphological, and paleoenvironmental information allowed us to demonstrate the influence of the environment on a key process that has produced much of Earth's biological diversity.

How to cite: Jovanovska, E., Stone, J., Salzburger, W., and Schrenk, F.: The influence of environment on adaptive radiation of diatoms in East African Rift lakes, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4430, https://doi.org/10.5194/egusphere-egu23-4430, 2023.

X3.38
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EGU23-5598
Christian Zeeden, Luc Grandolas, Mathias Vinnepand, Arne Ulfers, Mehrdad Sardar Abadi, Simona Pierdominici, and Thomas Wonik

Continuous limnic archives may record millions of years of climatic and environmental change at their locality. Typically, such archives reflect environmental conditions in the lakes’ catchments, but also the imprint of large-scale atmospheric systems e.g. related to insolation and/or global ice-sheet dynamics. These parameters may vary considerably in space and time, and our understanding on patterns across continents that relate to this forcing is still incomplete. Comparing sedimentation rates from limnic archives covering fundamental changes in the Earth’s system like the Mid-Pleistocene Transition (change from 41 kyr to 100 kyr cycle world) has potential to shed light into spatial differences in Earth’s climate response, if applied carefully.

In this context, we use age-depth models along with stratigraphic and chronological information e.g. from tephrochronology, magnetostratigraphy and tuning to assess differences in sedimentation rates of limnic geoarchives. We focus on limnic records that have been investigated during International Continental Scientific Drilling Program (ICDP) drilling projects, and specifically assess the influence of the Mid-Pleistocene Transition and the Mid-Brunhes Transition on sedimentation rates.

How to cite: Zeeden, C., Grandolas, L., Vinnepand, M., Ulfers, A., Sardar Abadi, M., Pierdominici, S., and Wonik, T.: Comparing lacustrine sedimentation rates and their response to climatic and environmental change, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5598, https://doi.org/10.5194/egusphere-egu23-5598, 2023.

X3.39
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EGU23-7938
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ECS
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Highlight
Cristina Corradin, Angelo Camerlenghi, Umberta Tinivella, Michela Giustiniani, and Claudia Bertoni

The knowledge of the global reservoir of submarine gas hydrates is of great relevance for understanding global climate dynamics, submarine geohazards, and unconventional hydrocarbon energy resources. Methane hydrate formation and preservation is favored by high pressure and low geothermal gradient and this leads the reservoir to be hosted mostly in cold passive continental margins. Several studies describe the Mediterranean basin's potential to host a Methane hydrate reservoir. However, in spite of the ample evidence of subsurface hydrocarbons, especially biogenic methane, widespread evidence of gas hydrate either from samples or seismic data is missing.  We modeled the theoretical Mediterranean distribution of methane hydrate stability field below the seafloor and in the water column using available geological information provided by 44 Deep Sea Drilling Project (DSDP) and Ocean Drilling Program (ODP) boreholes, measured geothermal gradients, and thermohaline characteristics of the water masses from CMEMS (Copernicus Marine services). We find that the pervasive presence of high-salinity waters in sediments, coupled with the uniquely warm and salty water column, limits the thickness of the theoretical methane hydrate stability zone in the subsurface and deepens its top surface. Because of the homogeneous characteristics of water masses, the top surface in the Mediterranean sea lays uniformly from 1163 to 1391 mbsl, much deeper than the oceanic basins where it lays around 300 - 500 mbsl. The theoretical distribution of methane hydrates coincides well with the distribution of shallow, low-permeability Messinian salt deposits, further limiting the formation of pervasive gas hydrate fronts and controlling their distribution due to the prevention of upward hydrocarbon gas migration. We conclude that the Mediterranean Basin, hosting the youngest salt giant on Earth, is not prone to the widespread formation and preservation of gas hydrates in the subsurface and that the gas hydrate potential of salt-bearing rifted continental margins may be considerably decreased by the presence of subsurface brines. This study was entirely conducted using data (stratigraphy, pore water salinity, and where available downhole temperature measurements) obtained with scientific ocean drilling, thus demonstrating the importance of the legacy data as a source of quality information even decades after their acquisition.

How to cite: Corradin, C., Camerlenghi, A., Tinivella, U., Giustiniani, M., and Bertoni, C.: Legacy scientific ocean drilling data suggest that subsurface heat and salts cause exceptionally limited methane hydrate stability in the Mediterranean Basin, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7938, https://doi.org/10.5194/egusphere-egu23-7938, 2023.

X3.40
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EGU23-9391
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ECS
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Stefanie Kaboth-Bahr, André Bahr, and Christian Zeeden

As the world warms due to rising greenhouse gas concentrations, the Earth system moves toward climate states without historic precedent, challenging societal adaptation. One way to investigate these unprecedented conditions is to study past climates and ecosystems that shar similarities to our current and future ones. One such period is the Eocene (~56 – 33 Ma), during which the climate changed from a hot-house to a greenhouse state, comprising a wide range of atmospheric CO2 concentrations. However, our knowledge of the Eocene climate evolution is incomplete because of a lack of terrestrial records covering the entire period. To address this gap in our understanding, we propose to obtain drill cores at Geiseltal in Eastern Germany as part of the International Continental Scientific Drilling Program (ICDP).

This former lignite quarry is famous for its exceptionally well-preserved Eocene mammal fossils, but its potential as a climate archive has not yet been explored due to the lack of existing drill cores. By drilling a maximum of three cores, we aim to create a spliced 100-120 m long record comprising the entire Eocene archived in Geiseltal as an alteration of lignite seems intercalated with fluvial strata. High-resolution, multi-proxy analyses of the obtained sediments will allow to generate a unique record of (sub)orbital climate variability under various atmospheric greenhouse gas concentrations. The integration of newly developed paleoclimate records with the existing paleoecological data will further help to inform how the terrestrial ecosystems reacted to long-term as well short-term changes, e.g., during hyperthermals. To advance this project, we welcome scientific input from a wide range of disciplines (e.g., stratigraphy, sedimentology, paleolimnology, paleobotany, paleontology, and organic/inorganic geochemistry) as well as are actively seeking interested groups and individuals to collaborate with us on this project.

How to cite: Kaboth-Bahr, S., Bahr, A., and Zeeden, C.: A proposal for drilling “Geiseltal” – a near complete terrestrial section of the Eocene in Central Europe, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9391, https://doi.org/10.5194/egusphere-egu23-9391, 2023.

X3.41
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EGU23-4301
Wolfram H. Geissler, Jens Gruetzner, Jens Matthiessen, A. Catalina Gebhardt, and Michael Schreck

During a long period of its Cenozoic history, the Arctic Ocean was isolated from any global thermohaline circulation system. Thus, the opening and subsequent widening of the Fram Strait, the only deep-water connection between the Arctic and Atlantic oceans, was a fundamental tectonic process with extensive consequences for the global ocean circulation and paleoclimate evolution as well as for sedimentation processes in the adjacent ocean basins and along the continental margins.

In order to reconstruct both the development of the ocean circulation within and the glacial history of the Arctic-Atlantic gateway we interpreted sediment packages imaged in reflection seismic profiles together with updated stratigraphic information from existing Ocean Drilling Program (ODP) holes. Our new, high resolution seismic stratigraphy for the Molloy Basin (central Fram Strait) is based on a revised chronology for ODP Site 909 and on reprocessed seismic reflection data with now better resolution than in previous studies.

An improved core-log-seismic integration for ODP Site 909 and crossing seismic reflection profile AWI-20020300 was substantial in deriving the new seismic stratigraphy as well as characterizing the seismic units lithologically (Gruetzner et al., 2022). The core-seismic integration was combined with a revised magnetostratigraphy calibrated by new palynomorph bioevents which shifts previously used stratigraphies for ODP Site 909 (e.g. Myhre et al., 1995) to significantly younger ages in the time interval from c. 15 Ma to 3 Ma. The new stratigraphy implies that prominent maxima in coarse sand particles and kaolinite, often interpreted as evidence for ice rafting in the Fram Strait occur at c. 10.8 Ma, c. 3 Myr later as previously inferred. In the late Tortonian (< 7.5 Ma), sediment transport became current controlled, most probably through a western, recirculating branch of the West Spitsbergen Current. This current influence was strongly enhanced between c. 6.4 and 4.6 Ma and likely linked to the subsiding Hovgaard (Hovgård) Ridge and the widening of the AAG. Late Pliocene to Pleistocene seismic reflectors correlate with episodes of elevated ice-rafted detritus input related to major phases in Northern Hemisphere ice sheet growth such as the prominent glacial inception MIS M2 and the intensification of Northern Hemisphere glaciation starting at c. 2.7 Ma.

Tracing the most prominent reflectors in a dense net (~5800 km) of re-processed seismic profiles allowed us to extrapolate these events into the western Boreas Basin and towards the adjacent Northeast Greenland continental margin. Subsequently compilations of updated digital isochron and depth-to-horizon maps were used to map depocenter geometries of current controlled sediments and mass-transport deposits within the western part of the Arctic-Atlantic gateway.

 

References

Gruetzner, J., Matthiessen, J., Geissler, W.H., Gebhardt, A.C., Schreck, M. (2022). A revised core-seismic integration in the Molloy Basin (ODP Site 909): Implications for the history of ice rafting and ocean circulation in the Atlantic-Arctic gateway. Global and Planetary Change, 215, 103876.

Myhre, A. M., Thiede, J., Firth, J. V., Ahagon, N., Black, K. S., Bloemendal, J., et al. (1995). Site 909. Proceedings of the Ocean Drilling Program, Part A: Initial Reports, 151, 159-220.

How to cite: Geissler, W. H., Gruetzner, J., Matthiessen, J., Gebhardt, A. C., and Schreck, M.: The opening of the Fram Strait and its influence on sediment transport, climate and ocean circulation between the Arctic Ocean and the North Atlantic, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4301, https://doi.org/10.5194/egusphere-egu23-4301, 2023.

X3.42
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EGU23-11937
André Bornemann, Oliver Friedrich, Kazuyoshi Moriya, and Howie Scher

At IODP Site U1407 (SE Newfoundland Ridge, IODP Expedition 342) a 270-m-thick sedimentary succession of Cretaceous and Paleogene age has been recovered. The two holes U1407A and B contain the transition from the reef basement to fine grained (hemi-)pelagic marls at ~270 mCCSF. The basal, incomplete short-cores of these two holes revealed a number of shallow-water fossils such as gastropods, corals, rudists and larger foraminifera (orbitulinids; Norris et al., 2014) from the top of the reef. In addition, a well-developed Cenomanian-Turonian Boundary (CTB) with its typical black shale expression of the Oceanic Anoxic Event 2 is represented in the cores. Here, we present a high-resolution carbon isotope record of the 40-m-thick succession from the top of the reef to the bathyal CTB black shales. Beside the typical δ13C anomalies associated with the CTB we identified the decline of δ13C values related to the top of the Albian-Cenomanian boundary interval and the Mid-Cenomanian Event. We further present new biostratigraphic results based on calcareous nannofossils as well as 87Sr/86Sr isotope ages for the top of the reef analyzed on Orbitulina. These new data in combination with the identified, stratigraphically well-calibrated events allow for a detailed comparison with other mid-Cretaceous records around the world and provide new insights into the subsidence history of the western Atlantic margin off Newfoundland.

Reference:
Norris, R.D., et al. 2014. Site U1407. Proceedings of the Integrated Ocean Drilling Program, Volume 342, doi:10.2204/iodp.proc.342.108.2014.

How to cite: Bornemann, A., Friedrich, O., Moriya, K., and Scher, H.: The Albian to Turonian record of IODP Site U1407 (SE Newfoundland Ridge), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11937, https://doi.org/10.5194/egusphere-egu23-11937, 2023.

X3.43
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EGU23-11575
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Highlight
Lara F. Pérez, Paul C. Knutz, John Hopper, Marit-Solveig Seidenkrantz, and Matt O'Regan

The projections of future scenarios under the current trend of global climate change demand a better understanding of the long-term ice-ocean-tectonic interactions, and in particular the potential meltwater contributions from modern ice sheets. The sensitivity of the Greenland Ice Sheet to polar amplification, changes in ocean heat transport and deteriorating perennial sea ice conditions makes the Northeast Greenland margin one of the most critical locations to understand the impact of future climate change on ice sheet instability and associated sea level rise. The development of oceanic gateways controlling the long-term water mass exchanges between the Arctic and Atlantic oceans, notably the Fram Strait and the Greenland-Scotland Ridge, have played a pivotal role for the Cenozoic evolution of the Northeast Greenland regions. In Northeast Greenland, ice-ocean-tectonic interactions and coupling between the ice sheet, ocean and sea ice are readily observable today, but geological records that can illuminate long-term trends are lacking. Consequently, NorthGreen MagellanPlus workshop was organised at the Geological Survey of Denmark and Greenland in collaboration with Aarhus (Denmark) and Stockholm (Sweden) universities in November 2022 as an international effort to develop Mission Specific Platform (MSP) proposals on Northeast Greenland margins under the umbrella of the European Consortium for Ocean Research Drilling (ECORD). For three days, seventy-one participants (56 in person + 15 online) discussed the key scientific questions and primary targets for scientific drilling in Northeast Greenland. Three pre-proposals have been initiated during the workshop targeting Morris Jesup Rise, Northeast Greenland continental shelf and Denmark Straight.

How to cite: Pérez, L. F., Knutz, P. C., Hopper, J., Seidenkrantz, M.-S., and O'Regan, M.: Scientific drilling in Northeast Greenland: Greenland Ice Sheet sensitivity to polar amplification and long-term ice-ocean-tectonic interactions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11575, https://doi.org/10.5194/egusphere-egu23-11575, 2023.

X3.44
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EGU23-17524
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Highlight
Renata Giulia Lucchi, Stefan Buenz, Andreia Aletia Plaza Faverola, Sunil Vadakkepuliyambatta, Jochen Knies, Michele Rebesco, and Kristen St. John

High-resolution depositional archives were identified in the contourite drifts developed on the mid-upper slope of the western continental margin of Svalbard (Bellsund and Isfjorden drifts, Vestnesa and Svyatogor ridges) under the persistent effect of the West Spitsbergen Current (WSC). The sediment drifts contain very similar stratigraphic sequences characterised by depositional marker beds (Heinrich-like and meltwater related deposits) outlining a synchronous, almost simultaneous response of the Svalbard-Barents Sea paleo-ice sheet to changing climatic conditions. These observations strengthened the idea that the WSC, transporting warm Atlantic Waters to the Arctic ,was one of the major drivers of the Arctic climate variability and cryosphere evolution in the area.

The considerations made above, inspired the writing of Proposal IODP 985-Full2 that was motivated by the necessity of retrieving continuous, high-resolution, and datable depositional sequences containing the record of the palaeoceanographic characteristics and cryosphere evolution during the past climatic transitions that followed the opening of the Fram Strait in the Arctic. Such data are greatly needed to better constrain global climate connections, forcing mechanisms and climate models. The general objective of 985-Full2 is the reconstruction of the variability of the WSC and its influence on climate changes particularly during key climate transitions (i.e. the late Miocene–Pliocene transition, late Pliocene–Pleistocene Transition, Mid-Pleistocene Transition, Mid-Brunhes Transition, and sub-orbital Heinrich-like events), its impact on the Arctic glaciations, ice shelves development and stability, and sea ice distribution over last 5.3 Ma.The proposal submitted in April 2020 was approved in May 2022 and scheduled as IODP Exp. 403 (June 4th to August 2nd, 2024).

How to cite: Lucchi, R. G., Buenz, S., Plaza Faverola, A. A., Vadakkepuliyambatta, S., Knies, J., Rebesco, M., and St. John, K.: The high-resolution paleoclimatic record of the western margin of Svalbard (Proposal IODP 985-Full2), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17524, https://doi.org/10.5194/egusphere-egu23-17524, 2023.

X3.45
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EGU23-8488
Timothy Henstock, Ingo Grevemeyer, Anke Dannowski, Milena Marjanovic, Helene-Sophie Hilbert, Adam Robinson, Yuhan Li, and Damon Teagle

A founding ambition of scientific ocean drilling is to drill a MoHole that penetrates the entire ocean crust and into the upper mantle at a location representative of normal crustal accretion and evolution. This remains the only way to test many of our key ideas about how new crust forms at mid-ocean ridges, cools and ages through interactions with the oceans. The technical challenges of drilling such a deep hole limit potential locations to a small number of candidate regions, which need to be sufficiently old to be cool at Moho depths but shallow enough for riser drilling.

In December 2022 and January 2023 RRS James Cook expedition JC228 carried out the first site survey to collect complete seismic datasets in one of the candidate regions, the Guatemala Basin. We collected two grids and a long flowline profile of multichannel seismic reflection (MCS) data using a tuned airgun array of 5000 in3 together with a 6 km hydrophone streamer. Airgun shots were simultaneously recorded on 52 ocean-bottom seismometers (OBS) deployed at 84 locations. Shot spacings of 150 m and 75 m were optimised for the different recordings. The survey samples crust formed between 19 and 21 Ma, at present-day water depths of 3200-3400 m, and is approximately along a flowline from the existing ODP/IODP Site 1256, where intact ocean crust has been drilled to the gabbros. Initial processing of the MCS data on board the ship shows a normal incidence reflection Moho that is variable in amplitude over distances of ~10 km, but is present at the intersections of several MCS profiles. Wide-angle PmP reflections on the OBS are clear across the region. There is obvious anisotropy in the Pn upper mantle refraction on the OBS, with a strong and high-velocity arrival along the flowline, and weaker and slower arrivals in the isochron direction at each grid. Overall, the initial observations are extremely promising for identification of multiple viable Mohole drilling locations.

How to cite: Henstock, T., Grevemeyer, I., Dannowski, A., Marjanovic, M., Hilbert, H.-S., Robinson, A., Li, Y., and Teagle, D.: Site survey for potential MoHole drilling sites in the Guatemala Basin, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8488, https://doi.org/10.5194/egusphere-egu23-8488, 2023.

X3.46
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EGU23-9728
Christine S Siddoway, Stuart N Thomson, Aaron Cavosie, Jan Alfaro, and Nels Iverson

Marine sediments, obtained from cores and captures from deep sea and continental shelf sites of West Antarctica, contain rich records of latest Miocene to Present glacial and deglacial processes and conditions at the margin of the West Antarctic ice sheet (WAIS). The materials we are investigating were recovered from a) Resolution Drift on the Amundsen Sea continental rise (water depths >3900m), b)the continental shelf in the Amundsen Sea, Wrigley Gulf, and Sultzberger Bay (water depths <1000m). Resolution Drift cores were drilled by IODP Expedition 379 (Gohl et al., doi:10.14379/iodp.proc.379.2021) in sediments dominated by compacted clay and silty clay, with conglomeratic intervals of ice-rafted detritus (IRD) and downslope deposits. The shelf sediments were recovered by piston core, trigger core, and Smith McIntyre Grab (SMG) during USA research cruises of the RVIB Nathaniel B Palmer (1999, 2000, 2007) and USCGC Glacier (1983). The shelf samples are non-compacted clay, containing abundant cobbles, pebbles and biogenic fragments.

Our research focuses upon rock clasts, detrital apatite and zircon, felsic volcanic tephra, and micro-manganese nodules separated from marine and glaciomarine clay. The rock clasts and detrital minerals represent samples of continental crust that we characterise according to rock type, petrology, geochemistry, and geo-thermochronology [U-Pb, (U-Th)/He, and fission track methods]. These characteristics illuminate solid Earth processes, including the development of subglacial topography . We compared clasts’ petrology and age data to the exposed onshore geology and thermochronology of bedrock, and determined that ≥90% of clasts likely originated in West Antarctica. Therefore the materials can be used to assign roughness, erodibility, and heat production factors for subglacial bedrock, which constitute boundary conditions used by ice sheet modelers.

Rhyolite ash and fragments provide new evidence for explosive eruptions (dated ca. 2.55 to 2.92 Ma; feldspar 40Ar/39Ar) delivered to sea as airfall, IRD, and possible subglacial water transport. Silicic eruptions produce ash and aerosols that may screen solar energy, and provide bio-available nutrients that produce phytoplankton blooms leading to sequestration of carbon. The rhyolite dates coincide with the end of a Pliocene warm period recorded in IODP379 cores (Gille-Petzoldt et al., 10.3389/feart.2022.976703). Our work in progress seeks to obtain higher resolution geochronology in order to determine whether silicic continental volcanism occurred in response to ice unloading due to deglaciation (cf. Lin et al., 10.5194/cp-18-485-2022) and whether erupted products contributed to latest Pliocene significant cooling and WAIS re-glaciation.

Another distinctive sediment constituent is micro-manganese nodules of unusual form. Whereas typical micro-MN nodules are dark, formed of concentric layers, this form is pale in color, ‘barbell’ shaped, and transparent in transmitted light. Scanning electron microscopy shows these to be microcrystalline Mn-oxide with embedded grains of quartz and feldspar, which likely served as seed material.  Mn-oxides form by authigenesis at/near the seafloor surface, requiring  high oxygen concentrations in the bottom water and low sedimentation rates, generally associated with the end of glacials/during interglacials (Hillenbrand et al. 2021, 10.1029/2021GL093103). Work is in progress to determine whether Mn oxides formed through passive accretion upon seed grains or microbially-mediated precipitation from Mn-oxyhydroxides or colloids, of possible relevance for coastal carbon budgets.

How to cite: Siddoway, C. S., Thomson, S. N., Cavosie, A., Alfaro, J., and Iverson, N.: Inventory of ice-rafted clasts and sediment constituents that pertain to dynamic ice-margin processes and biological productivity, Amundsen Sea region, Antarctica, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9728, https://doi.org/10.5194/egusphere-egu23-9728, 2023.

X3.47
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EGU23-10613
Yuri Kim, Sung Kyung Hong, Yoon-Mi Kim, Changyoon Lee, and Seok-Hwi Hong

Since rare earth elements and Yttrium (REY) were considered critical resources in modern technological and economic industries, deep-sea sediments in the world oceans have started to gain attention as an essential source of REY. In particular, recent studies have discovered that deep-sea sediments in the western North Pacific Ocean near Minamitorishima island have the highest REY concentrations (over 5,000 ppm of REY). In this study, our goals are to identify the existence potential of REY-rich sediment in the South Pacific Ocean and investigate REY abundance and distribution characteristics depending on lithofacies. We acquired the sediment samples from seven sites (U1365, U1366, U1367, U1368, U1369, U1370, U1371) recovered from Integrated Ocean Drilling Project (IODP) Expedition 329. The sediment samples were analyzed for bulk chemical composition, mineral composition, and sedimentary facies. The results indicate that REY concentrations ranged from 53 to 4,177 ppm. U1365 and U1366 sediments showed extremely high REY abundances over 2,000 ppm. On the other hand, U1368 and U1371 sediments showed the lowest contents of REY, less than 200 ppm. Based on the geochemical results, the sediments were divided into six lithofacies: Bioapatite-rich clay, Fe or Mn-rich clay, zeolitic clay, pelagic clay, siliceous ooze, and calcareous ooze. Bioapatite-rich clay with high P2O5 content contained the highest REY peak layers (1,141 ~ 4,177 ppm). We observed abundant fish teeth debris in the sediments composed of biogenic calcium phosphate. Fe or Mn-rich clay contained an average of 1,073 ppm of REY, indicating the second-highest abundance among the six lithofacies. XRD analysis and wet sieving results suggested that Fe or Mn originated mainly from goethite derived from hydrogenous and hydrothermal origins. Zeolitic clay and pelagic clay contained an average of 729 ppm and 344 ppm of REY, respectively. In addition, siliceous ooze and calcareous ooze showed an average of 152 ppm and 130 ppm of REY, respectively. These results imply that clay deposits are expected to have high REY contents than biogenic ooze. In addition, it implies that the main host phases of REY from deep-sea clay in the South Pacific are bioapatite and Fe or Mn (oxyhydr)oxides.

How to cite: Kim, Y., Hong, S. K., Kim, Y.-M., Lee, C., and Hong, S.-H.: Rare earth elements and Yttrium (REY) abundances and distribution characteristics depending on lithofacies in the South Pacific sediment, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10613, https://doi.org/10.5194/egusphere-egu23-10613, 2023.

X3.48
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EGU23-10649
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ECS
Nana Kamiya, Masataka Kinoshita, Weiren Lin, Takehiro Hirose, Yuzuru Yamamoto, Stephen A Bowden, Man-Yin Tsang, and Satoshi Tonai

Temperature is one of the important parameters to understand complex dynamics, because temperature of the crust is changed by some events such as volcanic activities and a passage of high temperature fluid, which affects physical property, chemical cycle and also microbiosphere. Therefore, information about temperature allow us to understand the dynamics of the active subduction zone.

IODP Site C0023, located at the tip of subduction zone in the Muroto transect of the Nankai Trough, was drilled by IODP Expedition 370. There, we measured the vitrinite reflectance which is an index of the maximum temperature experienced by the sediments. Comparing the measured reflectance and the model values calculated by assuming the past heat flow, it was found that Site C0023 experienced a higher heat flow than the present, which was approximately 160 mW/m2. However, the vitrinite reflectance is significantly higher than that in the above model just below the décollement, which suggested that another thermal anomaly originated directly under the décollement in addition to the high heat flow from the basement. With assumptions on the temperature of the heat source and the duration of heating below the décollement, we calculated the vitrinite reflectance in different models.

As a result, it was found that heat source temperature of 200˚C and heat generation duration of 500-1000 years are required just below the décollement to explain the depth distribution of the measured values. At Site C0023, a high pore pressure zone is distributed just below the décollement, which can serve as a path for fluids from deeper part. Considering that the temperature at the depth corresponding to the seismogenic zone in the Muroto area of the Nankai Trough is approximately 200˚C, and that a specific high temperature has not been confirmed just below the décollement of C0023 at present, the origin of the high-temperature fluid would be the deep seismogenic zone. Furthermore, the advection of high-temperature fluids is thought to be intermittent. In other words, the high reflectance just below the décollement is considered to indicate the advection of the high-temperature fluid from deep to shallow areas at the time of past earthquakes.

How to cite: Kamiya, N., Kinoshita, M., Lin, W., Hirose, T., Yamamoto, Y., Bowden, S. A., Tsang, M.-Y., and Tonai, S.: High temperature fluid flow through active décollement at the Nankai subduction zone, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10649, https://doi.org/10.5194/egusphere-egu23-10649, 2023.

X3.49
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EGU23-10280
Akinori Takeuchi and Harue Masuda

In the southwest Japan, located at the eastern edge of Eurasian plate, dehydrated water from subducting Philippine Sea Plate from the Nankai Trough issues without magmatic activity as thermal brines. Those brines contain high amounts of mantle derived components, and mercury may be one of those components. Mercury contamination is found in shallow groundwaters (>0.1 µg/kg) and soils (>200 µg/kg) along peripheral active faults of Osaka Basin, where subducting slab from the Nankai Trough appears deeper than the surroundings. Occurrence of the mercury contaminated groundwater also corresponds to the areas of deep low frequency tremor, which is known as a phenomenon occurring in relation to dehydration from subducting slab.

In order to specify the source(s) of mercury above described, mercury concentration and stable isotopes were analyzed for the sediments down to 2200 mbsf (meters below seafloor) taken from drilled cores at Kumano-nada basin IODP Site 0002, where accreted oceanic and forearc sediments are deposited. The mercury concentration, ranging 30-240 µg/kg, except three of 330-820 µg/kg of samples taken from ≥2000 mbsf. The range of 30-240 µg/kg is the same as those of surface sediments of ocean bottom of the study area. The high concentrations seemed due to high contribution of volcanogenic materials. The mercury stable isotopes values, –0.26 to –0.83 ‰ for δ202Hg and no shift of Δ199Hg and Δ201Hg, indicating geogenic origin without biogenic and/or photochemical alteration. The isotope values are in the similar range of those in the shallow groundwater in the Osaka Basin. The isotope values of δ202Hg are slightly smaller than that of mantle (0 ‰). These observations would be direct evidence that the mercury deposited in the subducting slab comes up with upwelling fluids.

Ocean scientific drillings have dissolved material cycles and the associating geological phenomenon, especially related to volcanic and seismic activities, at convergent margins related to subduction factory. From the point of views of concentration of useful elements, subduction factory is an important role for formation of ore deposits mainly via magmatic and the associating hydrothermal activities, which also cause the contamination of toxic elements. However, this study gives possible contamination of hydrosphere and pedosphere with toxic elements via non-volcanic tectonic activity.

How to cite: Takeuchi, A. and Masuda, H.: Recycling mercury at a convergent margin from Nankai Trough to southwest Japan, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10280, https://doi.org/10.5194/egusphere-egu23-10280, 2023.

X3.50
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EGU23-6134
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ECS
Gas sampling and monitoring during Drilling the Ivrea-Verbano zonE (DIVE)
(withdrawn)
Hugo Dutoit, Jessy Dominique, Andrew Greenwood, György Hetényi, Lorella Masci, Laurent Truche, and Thomas Wiersberg
X3.51
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EGU23-11796
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ECS
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Junjian Li, Andrew Greenwood, Eva Caspari, Simona Pierdominici, Jochem Kück, Ludovic Baron, and Marco Venier and the DIVE Drilling project Science team

The ICDP Drilling the Ivrea-Verbano zonE project (DIVE), aims at unravelling long-standing fundamental questions on the nature of the continental lower crust, its lithological correlation with geophysical anomalies and the characteristics of the underlying physical and chemical rock properties. Borehole geophysics provides an excellent opportunity and is the method of choice to explore the origin of geophysical anomalies, observed within the Ivrea-Verbano Zone, and their link to lithologies of the lower crust across several spatial scales. The first borehole of the DIVE project DT-1b in Ornavasso, Val’d Ossola (Italy), drilled into the Massone antiform, has been completed in December 2022 at a depth of 578.5 m. Geophysical borehole experiments comprising a suite of downhole logging and vertical seismic profiling (VSP) measurements have been conducted in two stages. A select set of first-look logs were collected to a depth of 315 m and a full suite at the end of drilling. The drilled rock types are metapelite, metapsammite, schist, gneiss, amphibolite, and, in places, migmatite and pegmatite. Several fractures are encountered within the drilled rock mass, exhibiting a NW-SE orientation and a variation of dip angles as identified by acoustic televiewer data. The acoustic televiewer data also show a couple of breakout zones, which may allow to constrain the current stress field orientation after carefully analyzing the impact of the topography. Preliminary results of the wireline logs suggest that they broadly correlate with the different rock types. Notably, the amphibolites as well as some of the more pelitic migmatites and gneiss exhibit locally high values of magnetic susceptibility of the order of 1000 10-6 SI. These values are confirmed by magnetic susceptibility measurements performed on drilled cores on-site with a self-built manual core scanner. Such high values have been reported in previous studies for amphibolites and mafic granulites in the Ivrea-Verbano zone and are most likely related to pyrrhotite and magnetite. Apart from the amphibolites, for most of the other rock types encountered, a weak correlation between magnetic susceptibility and the natural gamma radiation can be observed. The sonic P-wave velocities and preliminary P-wave velocity estimates of the VSP data are generally consistent. The average P-wave velocity estimate from the VSP is 5.3 km/s and slightly lower than the average estimate of 5.6 km/s obtained from the sonic logs. An integrated analysis of the complete set of the borehole geophysical data is currently undertaken to classify the rock mass with respect to their geophysical responses and to systematically delineate the underlying major factors of influence governing these responses.

How to cite: Li, J., Greenwood, A., Caspari, E., Pierdominici, S., Kück, J., Baron, L., and Venier, M. and the DIVE Drilling project Science team: Drilling the Ivrea-Verbano zonE project: DT-1b borehole geophysics, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11796, https://doi.org/10.5194/egusphere-egu23-11796, 2023.

X3.52
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EGU23-10947
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ECS
Assel Akimbekova, Massimiliano Rinaldo Barchi, Lauro Chiaraluce, Wade Johnson, M.Teresa Mariucci, Francesco Mirabella, Paola Montone, Simona Pierdominici, and Marco Urbani

The ICDP STAR drilling project (Strain Meter Array) is a joint research project among different institutions that aims to study the fault slip behaviour of the low angle Alto Tiberina Fault (ATF) in the Northern Apennines, Italy. The ATF is an active low-angle normal fault (mean dip 20°) whose activity and mechanics is still debated. Therefore, STAR drilled and instrumented six shallow boreholes, providing an excellent opportunity to study creep at local scale and over periods of minutes to months, poorly constrained by other geophysical instruments.

Two drilling campaigns were made in Fall 2021 and in Summer 2022, drilling a total of six 80-160 m deep vertical boreholes. Each borehole was instrumented with seismometers (three-component (3C) borehole geophones) and strainmeters (Gladwin Tensor Strainmeters, GTSM).  Strainmeters are the only instruments capable of measuring small creep events, as has been demonstrated near other creeping faults, such as the creeping section of the strike-slip San Andreas fault near Parkfield.

 

Two boreholes drilled the Mesozoic-Paleogene, Umbria-Marche carbonate succession (Maiolica, Marne a Fucoidi, Scaglia Bianca, Scaglia Rossa and Scaglia Variegata formations). The other four boreholes encountered the Neogene marls and turbidite sandstones (Schlier and Marnoso-Arenacea formations). Upon completion of the drilling operations, a suite of downhole logging measurements was performed in each borehole, comprising: total gamma ray, full wave sonic, electrical conductivity and temperature, caliper, resistivity, optical and acoustic borehole images. The sondes recorded data only in the deepest portion (open section) of the wellbore, except for the total gamma ray that run also in the cased section. The objective was to record the physical properties of the rocks in situ, and to reconstruct the spatial distribution and characteristics of the fractures (i.e. partially open, closed, thickness) and their connection with the geological structures mapped on the surface. 

 

Here we present a preliminary analysis of the logging data. In the carbonate units (i.e. Maiolica and Scaglia Rossa) the gamma ray shows low and flat curve (less than 30 cps) and P-wave velocity about 3 km/s. In the sandstone-marly units (Marnoso-Arenacea), encountered in three boreholes, the gamma ray records high values (about 80-100 cps) correlated mainly to marly intervals and P-wave velocity of 3-3.5 km/s. The hemipelagic marls of the Schlier Formation are characterized by high gamma ray (mean value of 80 cps) and by an average P-wave velocity of 3.5 km/s. These values will be compared with the results of laboratory analysis of samples, collected in similar lithologies, as well as with the results of logging performed in deeper wells drilled for commercial purposes. Through this comparison, we will evaluate the effect of depth (i.e. pressure) on the main physical properties of sedimentary rocks. The physical properties, in combination with the orientation and geometry of the discontinuities (fractures, veins, bedding), acquired by downhole logging, will contribute in building-up improved 3-D geological models of the ATF.

 

How to cite: Akimbekova, A., Barchi, M. R., Chiaraluce, L., Johnson, W., Mariucci, M. T., Mirabella, F., Montone, P., Pierdominici, S., and Urbani, M.: ICDP STAR drilling project in Italy: preliminary analysis of geophysical downhole logging data, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10947, https://doi.org/10.5194/egusphere-egu23-10947, 2023.