Proposal 918-pre in the Southern Ocean exists in the current science evaluation system of IODP. Site surveys were completed in 2019. We would like to develop an international research project based on this proposal by conducting new drilling/coring in the IODP³. First, we would like to drill by riserless drilling vessel, but if drilling is not feasible, we plan to consider giant piston coring as an option.

 The Southern Ocean (SO) is a key region that profoundly influences climate variability throughout the Cenozoic. Because the SO redistributes heat, fresh water, carbon, and nutrients around the global ocean it plays a key role in the climate system. The growth of ice sheets in the Antarctic continent and changes in sea ice in the surrounding ocean are important variables in Earth’s climate system. Upwelling of deep waters in the Antarctic Circumpolar Current (ACC), in particular, is a key process of the meridional overturning circulation (MOC) as it constitutes the return path for deeply-sequestered carbon and nutrients towards the surface and hence important in the partitioning of carbon between the ocean and the atmosphere. Furthermore, physical and biogeochemical processes modulate nutrient export through SO-sourced intermediate waters that ventilate 75% of the world’s thermocline, thus playing a vital role in influencing low-latitude productivity and ecosystems.

The western Indian sector of the SO, located at the confluence of the SO overturning cells and the MOC return surface flow, is a key region to document the links/teleconnections between the SO, global ocean/atmospheric circulations and hence climate (Fig. 1). It provides a unique opportunity to obtain exceptionally high-resolution sediment records to document and unravel the interaction and feedbacks between atmosphere, ocean and cryosphere from millennial to orbital-timescales during the late Neogene and Quaternary, focus on past 6 Ma (Fig. 2).

Specifically, the proposal aims to constrain further – (A) past changes in the upwelling and latitudinal position of the ACC; (B) the dynamic controls of circum-Antarctic deep ocean ventilation/overturning circulation; (C) their link to the global ocean circulation; (D) past changes in the sea ice coverage and dust inputs; and (E) their implications for the marine biogeochemical cycles of carbon and nutrients. The anticipated results will elucidate the evolution of the SO carbon cycle, identify potentially dominant physical and biogeochemical mechanisms of change, document past oceanic bipolar teleconnections with global MOC dynamics, and provide constraints on its future evolution in response to anthropogenic warming.

Our scientific objectives relate to Strategic Objective 3 (Earth’s climate system), Strategic Objective 4 (Feedbacks in the Earth system), and Flagship Initiative 1 (Ground truthing future climate change) in the 2050 Science Framework.

How to cite: Ikehara, M., Crosta, X., Jaccard, S., Naish, T., and Nakamura, Y.: Plio-Pleistocene Southern Ocean Paleoceanography: Latitudinal drilling in the Southwestern Indian sector of the Southern Ocean, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1949, https://doi.org/10.5194/egusphere-egu24-1949, 2024.

International Ocean Discovery Program (IODP) Expedition 366 recovered cores from three serpentinite mud volcanoes that also contain clasts that originate from the subduction-channel along the Philippine Sea Plate – Pacific Plate boundary. The drilled and sampled mud volcanoes (Yinazao, Fantangisña, and Asùt Tesoru) are located at distances of 55 to 72 km from the Mariana Trench.

In general the recovered cores comprise serpentinite mud with lithic clasts from the underlying forearc lithosphere and from the subducting Pacific plate. This aloows the reconstruction of mass transport processes and geochemical cycling within the forearc, the spatial variability of slab-related fluids within the forearc, and water-rock-reactions in subduction and supra-subduction zone settings, the metamorphic and tectonic history of the subduction channel, and the timing and rates of these processes.

Mafic rock clasts, embedded within a serpentine mud matrix, from the flanks and summits of both Asùt Tesoru and Fantangisña Seamounts were analyzed for reconstruction of their metamorphic and deformational overprint in order to reveal the tectono-metamorphic conditions at the metamorphic peak within the subduction channel and the subsequent low-grade overprint during exhumation.

Several seamounts comprise clasts of lower plate metabasites with different metamorphic overprint (from low-grade greenschist facies to lower blueschist facies). The metabasites are also associated with clasts of fossiliferous carbonates and cherts with different degrees of metamorphic and deformational overprint, that also originated from the Pacific lower Plate. This implies that these rocks were exhumed from different depths within the subduction channel before being regurgated within a serpentinite mud matrix. The blueschist facies metamorphic rocks, being affected by metamorphic pressures in the range of 11 to 13.8 kbar at minimum, were very likely exhumed from greater depth within the subduction channel before being captured by uprising, localized serpentine mud flows, indicating evidence that corner flow is actually taking place along the Mariana convergent margin, and, to our knowledge, this is the first direct evidence of exhumation of high-pressure rocks by corner flow in an active subduction zone. Final exhumation, however, is related to the embedding of the rocks within a serpentinite mud matrix and the buoyant ascent of serpentinite mudflows along forearc fracture zones extending from the plate boundary to the upper plate sea floor.

Biostratigraphic analyses of calcareous nannofossils and planktonic foraminifera from serpentinite mud flows, and intercalated pelagic sediments immediately above the metabasites analysed in this study give an age record of ~ 6.10 Ma (late Miocene, Messinian) to 4.20 Ma (early Pliocene, Zanclean), indicating that the final exhumation of the metabasites occurred during late Miocene times, slightly before 6.10 Ma.

How to cite: Kurz, W., Miladinova, I., Auer, G., and Del Gaudio, A. V.: Exhumation of high-pressure rocks by corner flow and serpentinite mud volcanism – implications from serpentinite mud seamounts along the Mariana convergent margin (IODP Expedition 366), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3044, https://doi.org/10.5194/egusphere-egu24-3044, 2024.

The abrupt onset of the Paleocene-Eocene Thermal Maximum (PETM) 56 million years ago represents one of the largest transient greenhouse gas-driven global warming event in the last 100 million years. Caused by a geologically rapid injection of exogenic carbon into the ocean and atmosphere system, the PETM is associated with large-scale ocean acidification. Related widespread dissolution of marine pelagic carbonate deposits, particularly in the early stages of the event, complicates marine paleoclimatic reconstructions and the establishment of robust age models at many sites. Recently, a new deep-sea sediment record spanning the PETM was recovered from the southern Agulhas Plateau in the Southwest Indian Ocean during International Ocean Discovery Program Expedition 392. The uppermost Paleocene/lowermost Eocene interval at Site U1580 was drilled in two parallel holes at 2560 m water depth, and consists of 75‒95% carbonate across the event, with a reduction to 75‒65% at the PETM onset. X-ray fluorescence-derived core scanning elemental data at 5mm and 10mm resolution and an unprecedented high-resolution bulk carbonate stable carbon and oxygen isotope record define a new marine composite reference record for the PETM at this site. The record is comparable to Ocean Drilling Program Site 690 (2914 m water depth) in the Atlantic sector of the Southern Ocean, where the event was first described and is still a primary reference sequence for paleoclimate reconstructions. Unlike Site 690, however, Site U1580 elemental data shows a clear cyclicity throughout the event that can be utilized for cyclostratigraphy. Additionally, the highly resolved bulk carbonate stable carbon isotope record provides a new reference for global correlation, which establishes a new benchmark for the different phases of the PETM. Here we present this new record and discuss the implications for timing and duration of the event, and set the stage for multi-proxy paleoclimate reconstructions spanning the PETM at IODP Site U1580.

How to cite: Westerhold, T., Bohaty, S., Penman, D., Burkett, A., and Dallanave, E. and the Expedition 392 Scientists: A new deep sea reference record for the Paleocene-Eocene Thermal Maximum: IODP Expedition 392 Site U1580 (Agulhas Plateau, Southwest Indian Ocean), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3074, https://doi.org/10.5194/egusphere-egu24-3074, 2024.

With an aggregated thickness of c.100 m, a porosity of up to 15 % and a permeability above hundred millidarcy, previous studies have assessed the three widely distributed Cambrian sandstone members in the Swedish sector of the Baltic Sea as the most potential CO₂-storage candidates in Sweden. Existing models indicate an effective storage capacity between 450–1500 Mt CO₂. However, these rough numbers are uncertain as they are related to vintage and partly inadequate data sets, especially regarding physical property values needed for a more certain evaluation of the storage capacity. Hence, as part of a larger screening and evaluation programme, launched by the Swedish government to identify and quantify potential storage sites in Sweden, two scientific core drillings were completed in 2023 on the southernmost part of the island of Gotland in the Baltic Sea. The primary aim was to collect complementary and missing data on the Lower Palaeozoic succession including both caprocks and reservoirs. The scientific evaluations and results of the core drillings on south Gotland will together with geophysical logging of the boreholes, new seismic data and 3D models constitute an essential part in improving the models of the effective storage capacity of the Cambrian reservoirs in the Swedish sector of the Baltic Sea. The coring, monitoring and investigations were managed by the Geological Survey of Sweden and the Swedish national research infrastructure for scientific drilling, “Riksriggen”, operated by the department of Engineering Geology at Lund university. H-dimension triple tube coring (96/61 mm hole/core diameter) was successfully performed with an Atlas Copco CT20C rig. The two wells, Nore-1 and Nore-2, penetrate 470 m of Silurian marlstone and claystone, 85 m of Ordovician argillaceous limestone and 225 m of Cambrian sandstone, siltstone and shale before finishing in the Precambrian crystalline basement of potassium porphyritic granite at 791.5 m and 787.7 m, respectively. The operation managed to reach the set goals despite challenges of over pressured formations and up to metre-thick bentonites. Initial results show a thick, tight, and homogenous caprock and that the Faludden Sandstone, one of the three Cambrian sandstone members, have hydraulic properties that qualifies it as a possible storage reservoir. The preliminary results from the two wells are here presented together with evaluations of drilling performance, monitoring programme, logging and test operations. 

How to cite: Erlström, M., Rosberg, J.-E., Dahlqvist, P., Hjerne, C.-E., and Lorenz, H.: Scientific core drilling of the Lower Palaeozoic succession in the Swedish sector of the Baltic Sea – investigation of the CO2 storage potential, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5974, https://doi.org/10.5194/egusphere-egu24-5974, 2024.

We have detected an event of pore pressure changes (hereafter, we refer it to “pore pressure event”) from borehole stations in real time in March 2020 and March 2023, owing to the network developed by connecting three borehole stations to the Dense Oceanfloor Network System for Earthquakes and Tsunamis (DONET) observatories near the Nankai Trough. Slow earthquake is thought to have longer duration time with smaller stress drop than regular earthquake under the same magnitude. This means that the slow earthquake is more sensitive to external stress perturbation and useful to monitor the processes of stress accumulation and release. However, the pore pressure is also affected by tidal and oceanic fluctuations. To overcome this problem, we use the seafloor pressure gauges of DONET stations nearby boreholes instead of the reference by introducing time lag between them. The obtained results demonstrate the detectability of volumetric strain change for nano-scale. We also investigate the impact of seafloor pressure due to ocean fluctuation on the basis of ocean modelling, which suggests that the decrease of effective normal stress from the onset to the termination of the SSE is explained by Kuroshio meander and may promote updip slip migration, and that the increase of effective normal stress for the short-term ocean fluctuation may terminate the SSE as observed in the Hikurangi subduction zone. The evaluation of the ocean impact is to be applied to a fiber-optic submarine cable, and 50 km-long distributed acoustic sensing (DAS) recordings, where the DAS measurement can be sensitive for hydroacoustic signals in a frequency range from 0.1 to a few tens of Hz.

How to cite: Ariyoshi, K. and Matsumoto, H.: Precise monitoring of subduction plate coupling status on the basis of DONET and borehole data analyses, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7109, https://doi.org/10.5194/egusphere-egu24-7109, 2024.

Megathrust earthquakes in subduction zones, such as the AD 2011 Tohoku-oki earthquake, are known to generate turbidity currents that transport sediment into deep marine trenches, creating distinctive event deposits. These deposits are pivotal in submarine paleoseismology, which seeks to extend earthquake records and assess disaster potentials by meticulously analyzing the spatiotemporal distribution of these deposits through precise distinction and correlation. In our research, over 800 meters of sediment cores from 15 sites along the Japan Trench were collected during the International Ocean Discovery Program (IODP) Expedition 386, focusing on these event deposits to trace earthquake history. Utilizing X-ray Fluorescence Core Scanning (XRF-CS), we performed efficient and non-destructive high-resolution analysis of the chemical characteristics of these deposits. Our methodology integrates XRF-CS data with multivariate statistical techniques, such as Principal Component Analysis (PCA) and Cluster Analysis (CA). This integration enables us to objectively differentiate and correlate event deposits based on their unique chemical properties. Significant discoveries were made at Site M0083, where we detected variations in background sediments and event deposits associated with major historical earthquakes, including the AD 1454 Kyotoku and AD 869 Jogan events. These unique chemical fingerprints were also traced to adjacent trench-fill basins at sites M0089 and M0090, revealing consistent event-stratigraphic sequences across the basins and affirming the efficacy of our chemical-based correlation technique. In our ongoing analysis, we aim to explore the diverse chemical fingerprints of background sediments, turbidite bases, and turbidite tails. This investigation seeks to uncover potential spatial and stratigraphic provenance changes, and includes examining mineral and biogenic compositions, such as clay minerals and smear slides, to elucidate the reasons behind variations in chemical signals. Our findings underscore the effectiveness of combining chemical analysis with statistical methods for event-stratigraphic correlation. This novel approach not only sheds light on provenance changes but also helps establish a detailed spatiotemporal distribution framework for event deposits along the Japan Trench. Moreover, this integrated methodology could inform subsequent sampling strategies by objectively selecting sampling locations based on the chemostratigraphy framework. It also has the potential to be adapted to other research areas that require event-stratigraphic correlation and comprehensive spatiotemporal analysis.

How to cite: Lin, J.-T., Huang, J.-J., Ikehara, K., Strasser, M., Hsu, T.-W., Su, C.-C., Shao, Y.-H., Wu, Y.-H., and Amano, A.: Chemical-Based Event-Stratigraphic Correlation along the Japan Trench by XRF-CS Chemical Fingerprint and Multivariate Statistics, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7120, https://doi.org/10.5194/egusphere-egu24-7120, 2024.

In the framework of the Research Infrastructures (RIs), scientific drilling represents a globally ranging, distributed RI that generates a wide variety of subsurface data. The ongoing project “Italian Integrated Environmental Research Infrastructures System (ITINERIS)” aims at building the Italian Hub of RIs in the environmental scientific domain by coordinating a network of national nodes from 22 RIs, including the Italian participation in the European Consortium for Ocean Research Drilling (ECORD) and in the International Continental Scientific Drilling Project (ICDP). The main goal of ITINERIS is to promote cross-disciplinary research in environmental sciences through the use and re-use of existing (or pre-operational) data and services and new observations, and to address scientifically and societally relevant issues.

The impact of ITINERIS on the Italian geoscientists involved in scientific drilling is twofold. First, it will improve the access to both the ECORD and the ICDP infrastructures. This will result in increasing the national participation in terms of proposal writing, drilling expeditions/projects, initiatives to use legacy samples/data, and training activities. Secondly, it will allow to collect and systematize the great amount of data produced by Italian scientists in the past scientific drilling programs (DSDP-ODP-IODP). This will facilitate the data handling and interoperability approach. A thematic digital archive of ECORD/ICDP-related data will be provided within the following thematic areas: micropaleontology, petrology, elemental and isotope geochemistry, paleomagnetism, stratigraphy/lithology, structural geology, borehole geophysics and site survey. This structured and accessible scientific dataset will represent a milestone for further implementation following FAIR data principles and best practices for ongoing and future drilling projects. Further developments of this digital archive might also serve as an additional tool to be integrated within the SPARCs initiative of IODP³.

How to cite: Iadanza, A., Argnani, A., Boschi, C., Camerlenghi, A., Casalena, G., Erba, E., Florindo, F., Giaccio, B., Kinkel, H., Sacchi, M., Schleifer, A., Tribuzio, R., and Vannucchi, P.: A legacy plan and an innovative access framework for the next decades of Italian geoscientists involved in scientific drilling: the role of ECORD/IODP-Italy in the ITINERIS project, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12110, https://doi.org/10.5194/egusphere-egu24-12110, 2024.

The Svalbard archipelago, located in the Norwegian High Arctic, preserves more than 650 million years of near-continuous sedimentary rock records spanning from the Neoproterozoic to the Cenozoic. The polar paleogeographic location of Svalbard in the late Mesozoic and the Cenozoic makes sites in Svalbard unique amongst well-studied temporally equivalent successions from lower paleolatitudes, allowing investigation of the polar amplification climatic effect over geological time. The sedimentary record of Svalbard has been largely controlled by northward drift of constituent geological provinces throughout much of the Phanerozoic and evolving tectono-stratigraphic environments including the influence of several Large Igneous Provinces (LIPs) and global climate fluctuations. 

The SVALCLIME initiative aims to systematically drill and core the sedimentary successions in Svalbard. Two sub-projects currently being evaluated by the ICDP materialized from an international workshop held in Longyearbyen in October 2022. The first is a full ICDP proposal focused on hyperthermals from the Permian to Paleogene (SVALCLIME P2P) and an ICDP-IODP Land to Sea preproposal on hothouse to coldhouse transitions in the late Paleozoic and across the Eocene–Oligocene transition (SVALCLIME Hot2Cold).

The SVALCLIME P2P project aims to investigate the high-resolution Arctic paleoclimate record from 255 to 45 Ma onshore Svalbard that encompasses several Mesozoic and Cenozoic hyperthermal events and the near-field impacts of three LIPs (the Siberian Traps, the High Arctic LIP and the North Atlantic Igneous Province). Our focus will also be on the deep biosphere to uncover the relationship between mineral substrates and taxonomic and metabolic diversity of intraterrestrial microbiomes. We propose to core seven boreholes at three locations (Nordenskiöldfjellet, Botneheia and Kropotkinfjellet), with a cumulative total cored length of ~3.4 km. 

The SVALCLIME Hot2Cold project aims to address global transitions from hothouse to icehouse conditions during the late Paleozoic and the Eocene to Oligocene. In the preproposal we identify suitable drill sites both onshore and offshore to characterize these periods. The Forlandsundet Graben in western Spitsbergen offers an opportunity to decipher the evolution of the Fram Strait and its impact on global oceanographic circulation during the Eocene–Oligocene transition. The Upper Carboniferous to Early Permian syn and post-rift deposits of the Billefjorden Trough will be targeted to investigate >130 cyclothems originating from glacioeustatic sea level fluctuations.

In this contribution, we outline the background and motivation of the SVALCLIME initiative and present the scientific objectives and the proposed drill sites.

How to cite: Kulhanek, D. K., Zuchuat, V., Jones, M., Barta, J., Foster, W. J., Geissler, W. H., Grundvåg, S.-A., Lorenz, H., Planke, S., Senger, K., Shepherd, G., Sliwinska, K. K., Smyrak-Sikora, A., Tarhan, L. G., Vickers, M., Weber, M., Xu, W., and Kramer, D.: SVALCLIME – Targeting deep-time Arctic climate archives of Svalbard, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14690, https://doi.org/10.5194/egusphere-egu24-14690, 2024.

A unique Seismic While Drilling (SWD) experiment, whereby a diamond coring drill rig as the seismic source has been conducted in the Val d’Ossola, Western Alps, Italy. For the SWD experiment 64 3C-sensors are employed in an array at the surface and the vibrational action of coring the rock acts as an active seismic source within the borehole. The maximum offset of the sensor array is 480 m with non-uniform spacing that increases with distance. The drilling operation took place from early October until mid-December 2022 and reached a depth of approximately 580 m. The seismic sensors recorded at a sampling rate of 1 ms, which is more than sufficient for an expected frequency of up to 200 Hz. The proposed SWD experiment is to evaluate the potential and limitations of the SWD method for diamond core drilling commonly utilized in scientific drilling projects with a focus on fundamental developments of the methodology and data processing techniques. Ideally the drill-bit seismic record should produce a seismic image around the bore hole and ahead of the drill bit. First it is important to determine if a signal can be detected, and to what depth, from a diamond core drill bit. In contrast to percussion or reverse circulation drilling, the diamond core drilling method produces a very weak signal. The seismic data is also heavily contaminated by coherent and random noises generated at the drill site, including rig engines, generators and mud-pumps, vehicles, and the movement of equipment. Separation of theses coherent noises using radon transform has thus far failed and other wavefield separation methods are investigated. Using seismic interferometric methods for unknown source positions, we aim to detect the weak signal at known drill bit positions. This is promising especially at drilling depths where the drill-rig and drill-bit wave-fields are spatial or temporal separated from each other, due to their different origins and velocities. Interferograms are obtained using the cross-coherence method, which is applied to the recorded passive seismic data. These are computed from 30sec time windows of the continuous recordings and then stacked into the final interferogram to increase the signal-to-noise ratio. Instead of migration summation, semblance is measured for the interferometric migration process. For the migration process, a constant velocity model is sufficient in this hard-rock environment. The major noise sources that we image are the vibrations of the drill rig and power generator, which appear to mask the weaker signal from the drill bit. In an ongoing second experiment, we utilize grid power, reducing the noise sources to the mud-pumps, rotating string, and rig.

How to cite: Trabi, B., Greenwood, A., and Bleibinhaus, F.: Seismic while drilling with a diamond drill bit in project DIVE DT-1B borehole in the Ivrea-Verbano Zone (Western Alps, Italy), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17124, https://doi.org/10.5194/egusphere-egu24-17124, 2024.

Growing evidence suggests that portions of the Antarctic Ice Sheet (AIS) could cross a tipping point over the next decades due to global warming. The Mid-Pliocene Warm Period (mPWP, 3.3-3 Ma, +2°C) is regarded as one possible geologic analog to the climate of the near future, and paleo-sea level during mPWP interglacials indicates that portions of the AIS were lost at that time. However, due to a lack of ice-proximal data, the timing, magnitude and trigger mechanisms of AIS retreats remain unconstrained. Here, we focus on the Ross Sea, where the IODP Exp. 374 Site U1523 recovered the first Antarctic Plio-Pleistocene record from a current-controlled sediment drift in an environment evolving from ice-proximal to open marine over time. U1523 is located where intrusions of warm deep water and outflows of cold water occur today, controlled mainly by the strength and route of the Antarctic Slope Current. To constrain the relative influence of oceanic currents and AIS dynamics on sediment erosion, transport and deposition across the Plio-Pleistocene transition (3.3-2.6 Ma), we integrate grain size, morpho-mineralogical, magnetic fabric analysis and geophysical logs from site U1523 with the multi-channel seismic line IT94-127A. We complement our dataset with a closeby box core (PNRA ODYSSEA exp., box core 08), that can be regarded as a present day analogue. Here, we present our morpho-mineralogical results on the box core and some specific intervals of the mPWP from site U1523. In particular, we perform single mineral Raman spectroscopy which, together with the entire suite of minerals and their relative abundance, highlight the different depositional environments and the source of the detritus, identifying local vs distant and magmatic vs metamorphic sources. Furthermore, we use the geophysical logs to perform rock physics correlation and we tie them to the seismic line, allowing the analysis to be extrapolated along the shelf.

How to cite: Ferrante, G. M., De Santis, L., Andò, S., McKay, R., Kulhanek, D., Gales, J., Perrotti, M., Zurli, L., Singh, S., Rebesco, M., Lucchi, R. G., Van Der Flierdt, T., Van Peer, T., and Morigi, C.: TriGgeR mechanisms of Antarctic ice sheet INStability across the Plio-pLeistocene trAnsitIoN - GRAINSPLAIN project, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19299, https://doi.org/10.5194/egusphere-egu24-19299, 2024.

The West Antarctic Ice Sheet (WAIS) is currently experiencing accelerated mass loss and contains enough ice to raise global sea levels by up to five meters if it were to melt completely. The objective of the international and interdisciplinary SWAIS2C project (Sensivity of the West Antarctic Ice Sheet to 2 Degrees Celsius of Warming) is to understand past and present factors influencing WAIS dynamics and to reconstruct WAIS response to warmer temperatures, including those exceeding the +2°C target outlined in the Paris Climate Agreement. The project will drill two deep boreholes beneath the Ross Ice Shelf to obtain sediment sequences from a site close to the grounding line of the Kamb Ice Stream site (KIS-3) and the Crary Ice Rise (CIR). The geological data will be used to improve model-based projections of future sea level contributions from Antarctica and to answer  the overarching question under what climatic conditions the WAIS collapsed in the past.

Here we present an overview of the SWAIS2C project, its’a aims and current progress. In the first season 2023/24, hot water drilling was successfully completed at KIS-3 to penetrate the ~580 m thick Ross Ice Shelf. Oceanographic measurements were taken in the ~55 m ocean cavity beneath the ice shelf, together with videos of the seafloor and ice shelf, and installation of permanent moorings. Gravity and hammer coring yielded 7.6 m of sediment, which have been subsampled for microbiology and geochemistry, and described using field-based x-ray images. The sediments recovered include the longest sediment core from the Siple Cost, measuring 1.92 m.

The sedimentological and drilling experience gained will be of great value for the 2024/25 season, when a team of drillers and scientists will return to KIS-3 for deep drilling with the Antarctic Intermediate Depth Drill (AIDD). A combination of hydraulic piston coring and rotary coring will be used to retrieve a sediment core of up to 200 m below sea floor. Drilling operations will be complemented by geophysical downhole logging with wireline tools from the Leibniz Institute for Applied Geophysics (LIAG) and a logging while tripping system provided by the German Research Centre for Geosciences (GFZ). The inclusion of different methods will allow downhole logging of several parameters over the entire sediment sequence and minimizes the influence of unstable borehole walls on the measurements.

How to cite: Ulfers, A., van de Flierdt, T., Levy, R., Dunbar, G., Horgan, H., Kulhanek, D., and Patterson, M. and the SWAIS2C Science Team: Sensivity of the West Antarctic Ice Sheet to 2° Celsius of Warming. The SWAIS2C project., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22323, https://doi.org/10.5194/egusphere-egu24-22323, 2024.

X-ray fluorescence (XRF) core scanning, renowned for its high-resolution, non-destructive, and user-friendly operation, is pivotal in geological research for analyzing chemical, physical, and biological signals. Despite the extensive applications of XRF data for various research purposes, the quantification of this data into specific geological proxies remains challenging due to the inherent non-linearity caused by simple sample pretreatment during core scanning. Leveraging advancements in deep learning, computing power and large-scale scientific drilling programs, our study aims to address this non-linearity by harnessing the often-overlooked raw XRF spectra stored in laboratory databases. We introduce an approach involving self-supervised pretraining on 54,643 spectra from marine sediments in the high-latitude sectors of the Pacific Ocean (cruises SO178, SO264, PS97, PS75, LV29). Our model, underpinned by a deep bidirectional image transformer (ViT-base), is trained to reconstruct heavily masked spectra (75%) with an R² accuracy of 0.996, demonstrating its proficiency in feature extraction from limited data portions. This foundational model is anticipated to serve as a versatile tool for various downstream geological applications after finetuning with specific labeled data, such as quantifying high-resolution calcium carbonate (CaCO₃) and detecting machinery anomalies. Future work includes expanding the spectrum database with diverse materials and machine settings to enhance the model's generalizability, ultimately broadening its applicability beyond core scanning for geological applications to encompass all XRF measurement techniques.

How to cite: Lee, A.-S., Lin, H.-T., and Liou, S. Y. H.: Pretraining Foundation Models: Unleashing the Power of Forgotten Spectra for Advanced Geological Applications, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4956, https://doi.org/10.5194/egusphere-egu24-4956, 2024.

The ICDP DSeis project accomplished full-core drilling and borehole-logging of the seismogenic zone of the 2014 M5.5 Orkney earthquake, South Africa. Three NQ-holes (total 1.6 km in length), drilled from 2.9 km depth at the Moab Khotsong gold mine, penetrated mostly intact hard rock, including 2.9 Ga meta-sedimentary and altered andesite (Crown) formations dipping ~20°SE. Subparallel altered gabbroic diorite sills intrude the formations.

After the borehole penetrated the Crown Formation and approached the steeply-dipping planar cluster of earthquake aftershocks, it encountered a potassic lamprophyre dyke several meters thick. The lamprophyre was intact close to the dyke contact, with mineral assemblages of augite, actinolite, and biotite. The talc and calcite content and magnetic susceptibility increased towards the centre of the dyke, while the augite and actinolite content decreased. The lamprophyre rock mass then became brecciated, with a substantial fraction of gouge. The Crown Formation adjacent to the dyke contact was also brecciated. Friction tests made on lamprophyre gouge (which contains about 20 wt% talc) yielded very low friction coefficients, similar to the results of previous wet friction experiments (Yabe et al. EGU 2024).

The DSeis drilling also intersected a non-potassic dyke rich in actinolite and chamosite about 300 m east of the potassic lamprophyre dyke. Whilst this dyke hosted no indications for aftershocks, the extracted brine was more hypersaline and older than any brine previously sampled from deep South African gold mines (Nisson et al., 2023). The hypersaline brine was non-meteoric in composition, with dissolved organic carbon concentrations sufficient to support deep life.

Both dykes show significant spatial variation in composition which we attributed to contamination/assimilation and metamorphism, depending on which formations (~20°SE dip) the dykes cut. We postulate that the localization of aftershocks in ‘streaks’ subparallel to the strata is a result of this compositional heterogeneity.

DSeis has successfully penetrated, sampled, and studied the aftershock sequence on the upper edge of the Orkney earthquake rupture. However, important questions regarding the nucleation and rupture of the earthquake that will only be solved by studying the strong motion source of the mainshock. The proposed PROTEA scientific drilling project aims to probe the Orkney earthquake's strong motion sources (the heart).

The existing DSeis hole, the new PROTEA hole, and the connecting horizontal tunnels at 2.9 km depth will allow us to deploy a 3D distributed acoustic sensing (DAS) network with a vertical span of several hundreds of meters, and a horizontal span of about 1 km. Using both active and passive seismic sources, we expect to image the 3D structure of the reflectors precisely.

Moab Khotsong has offered the team access to borehole cores that have sampled numerous dykes and sills; as well as access to the database of lithology and geological structure mapped on the mining horizons at 2-3 km depth. These data cover a much broader volume than the DSeis and PROTEA projects, and will significantly extend and enhance the interpretation.

Acknowledgements: South African gold mines, related firms, SATREPS, Kakenhi (21224012), ICDP, JSPS Core-to-Core Program, MEXT Kochi Core Center, NSF, DFG, NRF, Ritsumeikan and Kyoto Univs.

How to cite: Ogasawara, H., Yabe, Y., Durrheim, R., Manzi, M., Kieft, T., Nisson, D., Castillo, J., Gómez-Arias, A., Liebenberg, B., and DSeis and PROTEA, T.: From DSeis to PROTEA - Probing the heart of an earthquake, especially the interaction between metasedimentary rocks and mantle-derived intrusions. , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14233, https://doi.org/10.5194/egusphere-egu24-14233, 2024.