SSP1.3

Records of sulfur cycling during mass extinction events increasingly show that they are associated with rapid shifts in the sulfur isotope composition of seawater indicative of low concentrations of ocean sulfate [1-4]. These events are also often associated with the spread of anoxic conditions in the marine realm. We propose a feedback mechanism whereby the production of methane in marine sediments increases in proportion to decreasing sulfate and consumes bottom water oxygen, thus acting as a positive feedback on spread of anoxic waters. This can be further amplified via increased weathering or recycled fluxes of phosphate enhancing productivity [e.g. 5], the effects of increasing temperature on the rate of methanogenesis and the additional suppression of marine sulfate via increased pyrite burial.

We propose that sulfate drawdown occurs prior to climate forcing and other extinction drivers imposed by large igneous province (LIP) eruption. The likely mechanism for the drawdown of sulfate prior to these extinction is the removal of sulfate from the oceans as gypsum in evaporite deposits. Several large mid-Phanerozoic mass extinctions have clear evidence of increased evaporite deposition prior to, or approximately coincidental with LIP eruption and extinction.

If this idea is correct, the biological impact of a LIP will partly depend on the sulfate status of the ocean at the time of its eruption, and may at least partly explain the observation that whilst many mass extinctions are associated temporally with a LIP, not all LIPs seem to cause mass extinctions.

1. Newton, R.J., et al., Geology, 2011. 39(1): p. 7-10.

2. Song, H., et al., Geochimica et Cosmochimica Acta, 2014. 128(0): p. 95-113.

3. Witts, J.D., et al., Geochimica et Cosmochimica Acta, 2018. 230: p. 17-45.

4. He, T., et al., Science Advances, 2020. 6(37): p. eabb6704.

5. Schobben, M., et al., Nature Geoscience, 2020. 

How to cite: Newton, R. J., He, T., Dal Corso, J., Wignall, P., Mills, B., and Dunhill, A.: Ocean sulfate scarcity as a pre-condition for Large Igneous Province driven mass extinction, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-16391, https://doi.org/10.5194/egusphere-egu21-16391, 2021.

The Ireviken Biogeochemical Event (IBE) consists of the Ireviken Extinction Event (IEE) and is superseded by the Ireviken positive d13Ccarb Excursion (ICIE). During the Ireviken Extinction Event 80% of the conodont species and 50% of the trilobite species went extinct and Acritarchs, chitinozoans, graptolites, corals, and brachiopods communities were severely affected as well. Currently there are no indications that the Ireviken Biogeochemical event can be linked to a LIP or a bolide impact which are the usual triggers for most known biogeochemical events. The IBE has been tentatively linked to SEDEX brine expulsion, however convincing high-resolution data supporting the SEDEX brine expulsion theory was lacking.

The Altajme core from Gotland Sweden covers the entirety of the Ireviken Biogeochemical Event and using an ITRAX XRF core scanner  we were able to create a new dataset with a 1cm(~150-400 yr.) resolution. This dataset enables us to shed new light on the origin of the IBE and serves as a template for a cyclostratigraphic age model (using the detrital proxies of Ti and Al) which puts the IBE within a precise temporal framework.

The occurrence of peak values of Nb, Mn, Cu, Ba, Pb, Zn, As, Ag in the Altajme core follows the temporal sequence of element peaks which is characteristic for the cooling of a hydrothermal system. A Pb:Zn ratio of >1 and low Cu/(Zn+Pb) ratio categorises the hydrothermal system as being the sedimentary exhalative (SEDEX) brine expulsion type system. Through these results we can undoubtedly link the Ireviken Biogeochemical Event to a SEDEX brine expulsion. Numerous SEDEX style ore deposits of Proterozoic to Cenozoic age are known, but it has been difficult to connect them with similarly aged biogeochemical events.  This study demonstrates that through extremely high resolution XRF/element data we can observe the far-field signature of a SEDEX brine expulsion and thus showing us the way to recognize more biogeochemical events triggered by SEDEX brine expulsions. 

How to cite: Arts, M., Cramer, B., Calner, M., Rasmussen, C., Bancroft, A., Oborny, S., Hartke, E., Biebesheimer, E., and Da Silva, A.-C.: A sequence of temporally separated element peaks; the fingerprint of a biogeochemical event initiated by sedimentary exhalative (SEDEX) brine expulsion, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-12461, https://doi.org/10.5194/egusphere-egu21-12461, 2021.

The Permo-Triassic Extinction was the most severe in Earth history. The Siberian Traps eruptions are strongly implicated in the global atmospheric changes that likely drove the extinction. A sharp negative carbon isotope excursion coincides within geochronological uncertainty with the oldest dated rocks from the Norilsk section of the Siberian flood basalts. The source of this light carbon has been debated for decades.

We focused on the voluminous volcaniclastic rocks of the Siberian Traps, relatively unstudied as potential carriers of carbon-bearing gases. Over six field seasons we collected rocks from across the Siberian platform and show the first direct evidence that the earliest eruptions particularly in the southern part of the province burned large volumes of a combination of vegetation and coal. Samples from the Maymecha-Kotuy region, from the Nizhnyaya Tunguska, Podkamennaya Tunguska, and Angara Rivers all show evidence of high-temperature organic matter carbonization and combustion.

Field evidence indicates a process in which ascending magmas entrain xenoliths of coal and carbonaceous sediments that are carbonized in the subsurface and also combusted either through reduction of magmas or when exposed to the atmosphere. We demonstrate that the volume and composition of organic matter interactions with magmas may explain the global carbon isotope signal, and have significantly driven the extinction.

How to cite: Elkins-Tanton, L., Grasby, S., Black, B., Veselovskiy, R., Ardakani, O., and Goodarzi, F.: Field evidence for coal combustion links the 252 My-old Siberian Traps with global carbon disruption, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-9955, https://doi.org/10.5194/egusphere-egu21-9955, 2021.

The end-Triassic mass extinction (ETME) is thought to have been caused by voluminous, pulsed volcanic activity of the Central Atlantic Magmatic Province (CAMP). Over the last decades, various geochemical signals and proxy records, including δ¹³C, pCO₂, iridium and other platinum-group elements, mercury, polycyclic aromatic hydrocarbons (PAH), charcoal and SO₂, have been directly or indirectly attributed to CAMP magmatism. Here, we compile and discuss these various records in a stratigraphic framework to present a cohesive chain of events for the CAMP and the end-Triassic mass extinction. Mercury and iridium anomalies  indicate that CAMP activity commenced prior to the onset of the marine extinctions (as marked by the last occurrence of the Triassic ammonoid Choristoceras marshi or closely related species), and a negative δ¹³C excursion in organic matter (the Marshi CIE). This CIE may be explained by input of light carbon to the atmosphere from CAMP lavas of the Tiourjdal and Prevalent groups. Pedogenic carbonate below and above the Prevalent group in North America indicates a more than twofold increase in atmospheric pCO₂. Subsequent n-alkane C-isotopes, and stomatal pCO₂ data seem to indicate a temporary cooling after the Marshi CIE, which is consistent with climate models incorporating volcanic emissions of both CO₂ and SO₂. Records of excess iridium and Hg/TOC indicate intensified magmatism during the extinction interval. Tectonic and perhaps epeirogenic (i.e. doming due to rise of magma) activity is suggested by the occurrence of multiple and widespread seismites in Europe. Atmospheric pCO₂ proxies indicate global warming, which culminated contemporaneously with a second negative CIE (the Spelae CIE) at the level of the first occurrence of the ammonoid Psiloceras spelae, the index taxon fot the Triassic−Jurassic boundary (TJB). Global warming at this level is corroborated by increased wildfire activity testified by charcoal and pyrolytic PAH records. Just prior to the increase in pCO₂ from stomatal proxy data, fossil plants exhibit SO₂-induced damage indicating excess sulfur dioxide deposition priot to and across the TJB. This coincides with increased ratios of heavy molecular PAHs (coronene/benzo(a)pyrene) in sediments, which may suggest metamorphism of organic sediments also occurred across the TJB. This suggests that thermogenic release of light carbon and sulfur from sill intrusions in the Trans-Amazonian basins, where both evaporate- and organic-rich sediments are known to have been intruded, may have played an important role during the course of the ETME. Geochemical traces of magmatism, i.e. Ir and Hg, appear to have gradually disappeared during the Hettangian, suggesting that later phases of CAMP were less voluminous. Stomatal proxy data from Greenland and n-alkane C-isotope data from the UK, together with oxygen isotope data from carbonate fossils in the UK, may indicate that the global warming at the Spelae CIE was succeeded by another short-term cooling event. A gradual decrease in δ¹³C culminated at the top-Tilmanni CIE, marking the beginning of a long-term steady state with more negative C-isotope values than prior to the ETME. At this time, terrestrial ecosystems appear to have stabilized globally and ammonoids had begun to rediversify.

How to cite: Lindström, S., Callegaro, S., Davies, J., Tegner, C., van de Schootbrugge, B., Pedersen, G. K., Youbi, N., Sanei, H., and Marzoli, A.: Tracing volcanic emissions from the CAMP volcanism in the sedimentary and biotic record, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-10813, https://doi.org/10.5194/egusphere-egu21-10813, 2021.

Throughout Earth’s history, the coincidence in time between Large Igneous Province eruptions and mass extinctions points out a potential causality, where volcanic degassing may drive the global-scale climatic and environmental changes leading to biotic crises. The volcanic activity of the Central Atlantic Magmatic Province (CAMP, ca. 201 Ma), one of Earth’s most voluminous Large Igneous Provinces, is synchronous with the end-Triassic mass extinction event, among the most severe extinctions during the Phanerozoic. Combining different in situ analytical techniques (optical microscopy, confocal Raman microspectroscopy, EMP, SEM-EDS, and NanoSIMS analyses), bubble-bearing melt inclusions within basaltic rocks revealed the abundance of CO₂ (up to 1.0 wt.%) in CAMP magmas [1]. Gaseous CO₂ and solid elemental C, alternatively preserved by gas exsolution bubbles within melt inclusions mainly hosted in clinopyroxene crystal clots, represent direct evidence for large amounts of volcanic CO₂ (up to 10⁵ Gt) emitted into Earth’s surface during the entire CAMP activity [1]. The entrapment conditions of these melt inclusions within clinopyroxene aggregates constrain the degassed CO₂ to a mantle and/or lower-middle crustal origin, indicating a deep source of carbon which may favour rapid and intense CAMP eruption pulses. Each magmatic pulse may have injected CO₂ into the end-Triassic atmosphere in amounts similar to those projected for the anthropogenic emissions during the 21^st century [1]. Therefore, volcanic CO₂ degassed during CAMP eruptions likely contributed to end-Triassic global warming and ocean acidification with catastrophic consequences for the biosphere.

[1] Capriolo et al. (2020), Nat. Commun. 11, 1670.

How to cite: Capriolo, M., Marzoli, A., Aradi, L. E., Callegaro, S., Dal Corso, J., Newton, R. J., Mills, B. J. W., Wignall, P. B., Bartoli, O., Baker, D. R., Youbi, N., Remusat, L., Spiess, R., and Szabo, C.: Deep CO2 from the Central Atlantic Magmatic Province during the end-Triassic mass extinction, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-11189, https://doi.org/10.5194/egusphere-egu21-11189, 2021.

Studying the long-term evolution of nutrient cycles and their interaction with other biogeochemical cycles is essential to understand Earth’s history. Marine nutrient cycling forms a key control on the cycling of carbon and oxygen in the bio- and geospheres. Here, we focus on phosphorus, which is the ultimate limiting nutrient on geological timescales and a potential driver of past intervals of marine anoxia/euxinia. Despite its importance, obtaining direct information on spatial and temporal variations in marine phosphorus concentrations has proved challenging. Recent work has demonstrated the potential for calcium carbonate-associated phosphorus in corals to record water-column phosphorus (e.g., LaVigne et al., 2008; 2010). Building on this approach, we are investigating the use of other calcitic fossils as a proxy for water column phosphorus concentration, focussing on belemnites, an extinct group of nektic molluscs.

We have developed and optimised a method to quantify phosphorus in the belemnite rostrum, and initially applied this method to samples from the upper Sinemurian to the Toarcian in the Lower Jurassic. During this time there were major climatic and environmental events in the latest Pliensbachian and early Toarcian, which are thought to have been driven by large scale volcanism of the Karoo-Ferrar Large Igneous Provinces (LIP). Of particular interest are an icehouse event during the Pliensbachian, and a warming event during the Toarcian which coincided with widespread ocean anoxia (the Toarcian Ocean Anoxic Event [TOAE]) and a second order mass extinction event (the Early Toarcian Mass Extinction).

We will present P/Ca results from method development tests and collections of belemnites from the Sinemurian to the Toarcian from a number of sites in the European Epicontinental Sea (EES). Pilot data show similar trends in belemnite phosphorus concentrations at different sites in the EES, including a sharp peak during the TOAE. We will also discuss the impact of inter-species variation on belemnite phosphorus concentrations, as well as internal variability in phosphorus concentrations in individual belemnites, to determine the potential impact of these variables on the reconstruction of water column phosphorus concentrations. 

LaVigne, M., Field, M. P., Anagnostou, E., Grottoli, A. G., Wellington, G. M., Sherrell, R. M. (2008). Skeletal P/Ca tracks upwelling in Gulf of Panamá coral: Evidence for a new seawater phosphate proxy. Geophysical Research Letters 35.

LaVigne, M., Matthews, K. A., Grottoli, A. G., Cobb, K. M., Anagnostou, E., Cabioch, G., Sherrell, R. M. (2010). Coral skeleton P/Ca proxy for seawater phosphate: Multi-colony calibration with a contemporaneous seawater phosphate record. Geochimica et Cosmochimica Acta 74: 1282–1293.

How to cite: Roper, A., Ullmann, C., Little, C., Poulton, S., Wignall, P., He, T., and Newton, R.: A novel marine phosphorus record from Lower Jurassic belemnites?, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-2799, https://doi.org/10.5194/egusphere-egu21-2799, 2021.

Paleontological excavations realized by our group in Toarcian shales (Lower Jurassic) of the Grands Causses Basin in Roqueredonde (Hérault, France), yielded several specimens of marine vertebrates. The newly discovered specimens are partly or entirely preserved in anatomical connection and include a partial ichthyosaur skeleton with soft tissues, and a 4 m-long thalattosuchian longirostrine marine crocodile. A multi-proxy approach has been developed (XRD-bulk and clay mineralogy, Rock-Eval pyrolysis, phosphorus and mercury contents) in order to replace these findings in a well-defined temporal and paleoenvironmental context, and hence constrain the factors that led to their remarkable preservation. The fossiliferous succession exposes a 3 m-thick upper Pliensbachian interval of marl and nodular carbonate beds, overlain by a 3 m-thick interval of lower Toarcian laminated shales and limestone beds. Our high-resolution ammonite biostratigraphy, combined with inorganic and organic carbon isotope chemostratigraphy, shows that the fossiliferous Toarcian strata were deposited at a time of global warming and major carbon cycle perturbation known as the Toarcian Oceanic Anoxic Event (T-OAE). The studied succession shows several similarities with the classical coeval fossiliferous levels of the Posidonia Shale in SW Germany, including high organic matter and hydrocarbon contents as well as extremely reduced sedimentation rates. These results indicate that the unusual richness in well-preserved vertebrates of the studied site can be explained by a combination of warming-induced, low salinity and stratified waters, prolonged seafloor anoxia and reduced dilution by low carbonate and terrigenous input due to rapid sea-level rise. Our results also reveal a significant peak in mercury at the base of the T-OAE interval, consistent with that recorded in several coeval sections (e.g. Portugal, Morocco, Argentina, Chile). This mercury anomaly, most likely resulting from intense volcanic activity Karoo-Ferrar large igneous province, suggests that widespread exceptional vertebrate preservation during the T-OAE was initiated by a suite of severe environmental perturbations ultimately triggered by intense volcanic emissions.

How to cite: Bomou, B., Suan, G., Schlögl, J., Grosjean, A.-S., Suchéras-Marx, B., Adatte, T., Spangenberg, J., Fouché, S., Zacai, A., Gibert, C., Brazier, J.-M., Perrier, V., Vincent, P., Janneau, K., and Martin, J. E.: Record of the Toarcian oceanic anoxic event in the Grands Causses Basin (southern France) and its implications for vertebrate preservation, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-11835, https://doi.org/10.5194/egusphere-egu21-11835, 2021.

In the modern ocean, deoxygenation is a major consequence of climate change induced by eutrophication and expansion of oxygen minimum zones.  To better understand the exact mechanisms that promote the development of anoxia requires observations not available at human time scale, and therefore demand the study of intervals of rapid warming in the geologic past. During the Cretaceous Period, massive submarine volcanism during the construction of Large Igneous Provinces gave rise to the development of several episodes of widespread oxygen-depleted waters and enhance organic carbon deposition, including the  Cenomanian-Turonian Oceanic Anoxic Event 2 (OAE 2) and the  Late Turonian–Coniacian Event (LTCE). In this study, we reconstruct climate and oceanographic conditions in the Mexican Interior Basin during these events, a key area that connected the Western Interior Seaway to the equatorial Atlantic Tethyan water mass. To accomplish this, we applied an integrated multi-proxy approach that includes sedimentological, microfacies, mineralogical and geochemical data from a upper Cenomanian–lower Coniacian section.

Organic-rich sediments were accumulated during the initial stage of OAE 2 and the middle stage of LTCE (Hitchwood Event), under increasingly warm and humid conditions, as evidenced by high chemical index of alteration (CIA) values. High detrital index (DI) values coupled with high phosphorus mass-accumulation rates suggest that this scenario increased detrital and nutrients fluxes. Eutrophic-anoxic/dysoxic marine conditions are corroborated by the highest TOC values coinciding with significant enrichments in redox- and productivity-sensitive trace elements. Moreover, they are supported by the abundant presence of radiolarians and filaments in the OAE 2 interval, and the occurrence of opportunistic foraminifera in the LTCE interval. Oxygen-depleted bottom waters are also indicated by Mo–U systematics and a small-sized population of pyrite. The onset of the Mexican Orogen tectonic uplift together with upwelling intensified the transference of nutrients and enhanced organic matter burial during the initial stage of OAE 2. In the mid-OAE 2 δ¹³C trough interval equivalent to the Plenus Cold Event, bioturbated sediments with low TOC values accumulated during a short episode of cold climate conditions reflecting the southward flow of boreal water throughout the Mexican Interior Basin. The minimum δ³⁴S_py value occurring within the OAE 2 interval in the Mexican Interior Basin is lower than elsewhere due to a local increase in sulfate concentrations.

How to cite: Nunez, F., Colin-Rodríguez, A., Adatte, T., Omaña-Pulido, L., Alfonso, P., Pi, T., Correa-Metrio, A., Barragán, R., Martínez-Yáñez, M., and Enciso Cárdenas, J. J.: The Cenomanian–Turonian Oceanic Anoxic Event 2 and the Late Turonian-Coniacian Event in the Mexican Interior Basin, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-13968, https://doi.org/10.5194/egusphere-egu21-13968, 2021.

The Oceanic Anoxic Event (OAE) 2 spanning the Cenomanian-Turonian boundary (93.5 Ma)
represents a major perturbation of the global carbon cycle and is marked by organic-rich
sediments deposited under oxygen-depleted conditions. In many studies the eruption of the
Caribbean LIP is considered to be the cause for rapidly increasing CO2 concentrations and
resulting global warming accompanied by widespread oceanic anoxia. In the Lower Saxony
Basin of northern Germany, the deposits of the OAE 2 are exposed in several industry drill
cores. In this study, the lower part of the OAE 2 has been studied in the HOLCIM 2011-3 drill
core. Sedimentary rocks are composed of limestones, marly limestones, marls and black
shales and have been analysed with a high-resolution stable isotope approach
(approximately one sample every 2 cm) combined with geochemical modelling. Using stable
carbon isotopes, bulk rock parameters and petrographic analysis, the onset of OAE 2 has
been investigated in detail. The high-resolution δ¹³C curve exhibits overall stable values
around 3 ‰ before the onset of the Plenus event. This background level is interrupted by
three short-lived and small but significant negative carbon isotope excursions (CIEs) down to
δ¹³C values of 2.5 ‰, 2.7 ‰ and 1.9 ‰. Immediately before the main rise in the Plenus bed,
a longer-lasting negative CIE down to 2.8 ‰ is observed, preceding the large positive CIE of
the OAE 2 to values of 5.2 ‰ over 33 ka. Thereafter, the δ¹³C values decrease to 3.5 ‰ over
a period of approximately 130 ka. The results can be correlated with the lower-resolution
data set of Voigt et al. (2008) but enable a more accurate characterization of the subtle
features of the CIE and hence events before and during this time interval. Carbon cycle
modelling with the modelling software SIMILE using a model based on Kump & Arthur (1999)
reveals that the negative excursion before the Plenus bed can be explained by a massive
volcanic pulse releasing of 0.95*10¹⁸ mol CO2 within 14 ka. This amount corresponds to only
81 % of the calculated volume of CO₂ release during emplacement of the Caribbean LIP by
Joo et al. (2020). In the model the volcanic exhalation increases atmospheric CO₂
concentrations. This will increase global temperatures, intensify the hydrological cycle and
thus increase nutrient input into the ocean, resulting in an expansion of the oxygen minimum
zone, the development of anoxic conditions and an increase in the preservation potential for
organic material. In the model enhanced primary productivity and organic matter preservation
can be controlled by the implemented riverine phosphate input and the preservation factor for
organic matter. For the positive anomaly, the riverine phosphate input must be nearly
doubled (from 0.01 μmol/kg PO₄ to 0.019 μmol/kg) for the period of the increasing δ¹³C
values (app. 33 ka), with a concomitant rise of the preservation factor from 1 % to 2 %. This
model scenario accurately reproduces the major features of the new high-resolution δ¹³C
record over the onset of the OAE 2 CIE.

How to cite: Müller, P., Heimhofer, U., and Ostertag-Henning, C.: Onset of Oceanic Anoxic Event 2 in the Lower Saxony Basin – Insights fromhigh-resolution stable isotope stratigraphy and geochemical modelling, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-8748, https://doi.org/10.5194/egusphere-egu21-8748, 2021.

The cause of the Cretaceous-Paleogene extinction remains debated between an asteroid impact and volcanism. Precise geochronology showed that the extinction coincided with a voluminous phase (Poladpur eruption) of Deccan volcanism (Schoene et al., 2019). Paleontological evidence indicates that microfossil diversity declined about 300,000 years before the K-Pg boundary, synchronous with the onset of Deccan volcanism (Keller et al. 2009). High concentrations of Ir in the K-Pg boundary supported the asteroid hypothesis but recent work indicates that siderophile accumulation at the K-Pg in El Kef is secondary (Humayun et al., this conf.). Here, we critically examine existing element data for the K-Pg boundary and examine new results at the El Kef site, Tunisia, for volcanogenic volatile element accumulation associated with the contemporaneous Deccan eruptions. In this study, we analyzed 60 elements by laser ablation ICP-MS in search of these volcanic aerosol enrichments in the K-Pg sediments at El Kef, Tunisia. A study of siderophile element distribution at global K-Pg sites found that the Ru/Ir ratio is sub-chondritic. Mixing of upper continental crust (Ru/Ir> CI) with a chondritic impactor fails to explain this trend. Volcanic aerosol emissions for Ir are well known but there is less data available for Ru. Relative emission rates of Ru were found to be lower than those of Ir for the Kudryavy volcano (Yudovskaya et al., 2008), so a possible explanation of the sub-chondritic Ru/Ir ratio observed in global K-Pg sites involves deposition of volcanic aerosols in sediments. We also modeled the effect of adding volcanic aerosols to sediments approximated compositionally as upper continental crust (UCC) to find that Re, Cd, Os and Ir are the first elements to become enriched in sediments by volcanogenic aerosol deposition. Sediments from El Kef below the K-Pg boundary are enriched in both Re and Cd. On a plot of Cd vs. Re, the K-Pg sediment from El Kef falls on a mixing line between volcanic aerosol (Erta Ale volcano) and UCC. Sediment at 3 cm above the K-Pg boundary has little enrichment of either Cd or Re, interpreted here to indicate that this sediment was deposited in the interlude between the Poladpur and the Ambenali eruption phases of the Deccan. The availability of chemical proxies of volcanogenic aerosol deposition in sediments enables direct correlation between fossil evidence and the contemporaneous intensity of volcanic outgassing, the likely destroyer of life by the Deccan eruptions (Keller et al., 2020).

How to cite: Sillitoe-Kukas, S., Humayun, M., Adatte, T., and Keller, G.: Evidence for contemporaneous Deccan volcanic aerosol deposition preceding the K-Pg boundary at El Kef, Tunisia, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-400, https://doi.org/10.5194/egusphere-egu21-400, 2021.

The end-Cretaceous mass extinction is a unique event such that it potentially coincides with both the Chicxulub bolide impact and the Deccan volcanism. Among these two drivers, the role of the Deccan volcanism is crucial to decipher if there is a causal relationship between volcanism and environmental stress, and if so, how stressed the environment was during the latest Maastrichtian. To assess the cause-and-effect relationship between Deccan volcanism and climate change and mass extinctions, high-resolution biostratigraphy, quantitative species analysis coupled with geochemical measurements have been performed on complete sections of Mudurnu-Göynük and Haymana basins (Turkey).

Detailed quantitative study on planktonic foraminifera of the Haymana Basin revealed that planktonic foraminiferal community in the latest Maastrichtian is dominated by ecological generalists with small, simple morphologies (e.g., Heterohelix, Globigerinelloides, Guembelitria). Among them low oxygen tolerant Heterohelix globulosa is the most dominant taxa and their abundance changing with the presence of stress marker Guembelitria cretacea. In all sections, the K/Pg boundary itself is characterized by 2-3 mm thick reddish oxidized layer which corresponds to sudden annihilation of large, ornamented ecological specialists (e.g., Globotruncana, Rugoglobigerina, Racemiguembelina). Right after the boundary, there is an acme of calcareous dinoflagellate cysts (Thoracosphaera) and a surge of Guembelitria cretacea indicate ecosystem collapse in post-K/Pg environment.

On the other hand, detailed quantitative analysis shows a systematic reduction in the species richness throughout the Plummerita hantkeninoides Zone corresponding to the final 150 kyr of the Cretaceous. Proliferations of the Guembelitria cretacea through late Maastrichtian is known as an indicator of high terrigenous influx; therefore, enhanced food resources. The high sedimentation rates observed in all the studied sections might be linked to increased greenhouse conditions due to Deccan volcanism leading to enhanced weathering. Overall, our multiproxy approach including quantitative biostratigraphy and geochemical analyses highlights the influence of the Deccan volcanism by releasing high amounts of atmospheric CO₂ and SO₂, leading to the climatic changes and associated biotic stress, which predisposed faunas to eventual extinction at the K/Pg boundary.

How to cite: Karabeyoglu, A. U., Lorenzo, V., Spangenberg, J., Özkan-Altıner, S., Altıner, D., and Adatte, T.: Planktonic foraminiferal and geochemical record across the Cretaceous-Paleogene boundary (K-Pg): evidence from the Neo-Tethys, Turkey, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-2058, https://doi.org/10.5194/egusphere-egu21-2058, 2021.

The composite profile, with 4 studied sections, is located near the Uzgruň village (Czech Republic) next to a small stream. The profile is composed of Late Maastrichtian to Palaeocene flysch sediments and the K-Pg boundary is set in claystones within this turbiditic setting. Ongoing research of local paleoenvironment and stratigraphy is based on paleo- and rock-magnetic methods, micropaleontology and geochemistry to obtain more detailed view of the local situation during the K-Pg extinction event. Based on biostratigraphy, two dinocyst zones (Bubík et al., 2002): Palynodium grallator and Carpatella cornuta (first occurrence in the Danian), two calcareous nannofossil zones in the Upper Maastrichtian, and the agglutinated foraminifer zone Rzehakina fissistomata in the Paleogene were distinguished. Biostratigraphic data support the K-Pg boundary interval. The uppermost Maastrichtian is indicated by nannofossil species Micula prinsii, UC26d^TP zone. Basal Paleogene non-calcareous strata contain dinocyst Carpatella cornuta and agglutinated foraminifers of Rzehakina fissistomata zone. The presence of low-latitude nannofossil taxa M. prinsii and Ceratolithoides kamptneri show input of warm waters during the uppermost Maastrichtian. Several rock-magnetic methods, such as acquisition of Isothermal remanent magnetization (IRM), acquisition of Anhysteretic remanent magnetization (ARM), Anisotropy of magnetic susceptibility (AMS), Field dependence of magnetic susceptibility (HD) and Frequency dependence of magnetic susceptibility (FD), were applied to estimate behaviour and origin of magnetic particles. Natural remanent magnetization (NRM) values of samples range from 0.09 to 2.48 mA/m. Volume normalized magnetic susceptibility (MS) show values from 130 up to 1197 SI*10-6. There is no increase observed in MS across stratigraphic boundary due to turbiditic evolution of sediment. Due to character of sediments, we applied alternating field (AF) demagnetization and used principal component analysis (PCA; Kirschvink, 1980) for estimation of characteristic remanent component. Most of the K/Pg sections worldwide have well documented Iridium anomaly. In Uzgruň, the preliminary results show that although the values are not as pronounced, the Ir at K-Pg boundary is still higher than in surrounding sediments. For tracing of Deccan traps effect we plan to apply mercury (Hg)/total organic carbon (TOC) stratigraphy. TOC content of 20 pilot samples is low, but not under detection limit of the instrumentation (mean value 0.92 wt%). One sample reached value 4.41 wt% of TOC. Sulphur contents are reaching 1 wt%, but several samples were under detection limit of the instrumentation. Sulphur concentrations suggest more reduction conditions of burial.

Current research is supported by Czech Science Foundation project no. 19-07516S and is in accordance with research plan no. RVO67985831.

Bubík, M., Adamová, M., Bąk, M., Franců, J., Gedl, P., Mikuláš, R., Švábenická, L., & Uchman, A. (2002). Výsledky výzkumu hranice křída/terciér v magurském flyši u Uzgruně. Geologické výzkumy na Moravě a ve Slezsku, 9, 18–22

L. Kirschvink (1980), The least-squares line and plane and the analysis of palaeomagnetic data, Geophysical Journal International, 62(3), 699–718, https://doi.org/10.1111/j.1365-246X.1980.tb02601.x

How to cite: Kdýr, Š., Elbra, T., Bubík, M., Schnabl, P., and Švábenická, L.: Multi-proxy study of the Cretaceous-Paleogene (K-Pg) boundary in deep-sea turbiditic sediments in the Uzgruň section (Outer Flysch Carpathians, Czech Republic), EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-2625, https://doi.org/10.5194/egusphere-egu21-2625, 2021.

Western Carpathians transitional sequence of Upper Cretaceous (e.g. Gosau Group) and Paleogene (e.g. Myjava-Hričov Group) sediments provide good premise for studying the Cretaceous-Paleogene boundary (K-Pg) as well as other end-Cretaceous to Middle Eocene events. In Slovakia, the Late Cretaceous formations of Gosau localities can be found in Brezovské Karpaty Mts, Myjava Upland and Mid Váh Valley. To gain insights to local changes in global cataclysm event, a combined study of planktonic bioevents and magnetic properties across K-Pg was studied in two Western Carpathians drilled sections, Žilina (Mid-Váh Valley region) and Kršteňany (Upper Nitra Depression).

The Žilina-Hradisko drill core (ZA-1) is 75 m long and overturned in position. The micropaleontological research of the ZA-1 drill core provides a stratigraphic data ranging from the Late Maastrichtian to Early Ypressian. The ZA-1 sequence reveals distinct changes in magnetic properties and bioproductivity, particularly at the K-Pg. Although most of the drilled sequence displays paramagnetic behavior and low remanent magnetization (average magnetic susceptibility 142μSI and NRM <1mA/m, respectively), at the K-Pg and during first half of Danian – up to base of P2 biozone, markedly higher magnetic susceptibility (MS) and NRM values were observed. This change could mostly be attributed to increased concentration of magnetic fraction and probably illustrates the paleoenvironmental changes as a result of the K-Pg event. The K-Pg interval is also marked by the presence of increased amount of superparamagnetic particles. A mixture of low and high coercivity minerals were detected throughout the drill core, with S-ratio varying between 0.2-0.9 (at K-Pg 0.6-0.9). An additional study of mercury (Hg) content, in combination with total organic carbon (TOC), of ZA-1 samples, reveals a short time enhanced (Hg/TOC >100ppb/wt%), possibly volcanogenic, Hg input during Late Maastrichtian 40cm below K-Pg and later in the second half of P1 biozone in Danian, but seems to indicate either weak or no correlation with magnetic properties. The Kršteňany section consists of two boreholes, KRS-1 and KRS-3, and comprises Late Cretaceous – Middle Eocene formations. Similarly to ZA-1, most of the KRS-3 displays paramagnetic behavior (MS <300μSI) and low NRM (<2mA/m). However, contrary to ZA-1, the distinct changes in magnetic properties at K-Pg interval were not observed. The Maastrichtian portion of KRS-3 displays elevated, but decreasing towards K-Pg, MS values due to considerable weathering and increased hematite and/or goethite content in red-bed formation in the bottommost part of the core. Paleocene sequence through middle Ypresian shows lowest MS with higher (in pelagic sequences) and lower (in siliciclastic sequences) MS zones, probably following transgressive-regressive cycles.

The research was supported by Czech Science Foundation project no. 19-07516S and by VEGA agency no 2/0013/20, and is in accordance with research plan no. RVO67985831.

How to cite: Elbra, T., Kdýr, Š., Schnabl, P., Pruner, P., and Soták, J.: The rock magnetism and biochronology of boundary events across the Cretaceous-Paleogene transition in Slovakia., EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-5005, https://doi.org/10.5194/egusphere-egu21-5005, 2021.

The Kara astrobleme is one of the biggest meteoritic craters which is set at the Baydarata Bay of the Kara sea (European Arctic Zone, Russia). It is a result of the catastrophic impact event occurred close to the K/Т extinction. The Kara astrobleme is the largest European crater at the modern erosion level.  At present it is estimated with the diameter from rim to rim about 65 km. While, some scientists have proposed its larger initial size – up to 120 km diameter, but no any well presented proof has been provided for the hypothesis. In 2015-2019 we have provided wide geological observations at the Kara crater and the near-set Ust`-Kara area (UKA) impactites. We have found for the first time that the UKA impactites, described in earlier Russian scientists publications as a synchronic independent crater of the same bolide, can be presented with bottom-flow impactites from the Kara crater (Shumilova et al., 2020). The found bottom-flow impactites abundant with belt-like impact melt bodies enriched in coesite and liquation structures similar to the Kara UHPHT vein and vein-like melt bodies with UHPHT impact glasses. Thus, they belong to UHPHT impactites. According to our air-bird view observations and impactites outcrops description at the UKA we support the hypothesis of the larger Kara crater getting 100-120 km in diameter of the initially originated size. Such giant meteorite event should be followed by catastrophic effects at the planet level, such as mass extinction. The present accepted Kara impact event age followed by the most recent measurements by ⁴⁰Ar-³⁹Ar method is equal to 70.3 ± 2.2 Ma (Trieloff et al., 1998), that is a bit earlier than the Cretaceous/Tertiary boundary (K/Т) mass extinction at 66 Ma. But, previously, Kara age has been proposed by 65.7 Ma as a probable K/T impact (Kolesnikov et al., 1988; Nazarov et al., 1992). According to different data, the Kara event age lies within the range from 60 to 81 Ma (Masaitis & Mashchak, 1982; Nazarov et al., 1989; Kolesniov et al., 1990; Koeberl et al., 1990). It is clear that the accuracy of the age measurements depend on the quality of the studied samples, including their crystallinity, velocity of impact melt cooling and alteration, and from the used type of a method. By the moment, we have found out “in situ” crystallized zircons within the just discovered real UHPHT impact melt glasses (Shumilova et al., 2018, 2020). The UHPHT glasses do not have any alteration, thus, they can be used for accurate age measurements. Taking a future possibility for more accurate age analysis in the nearest future we can propose a correct vision of the possibility of the giant Kara influence to K-T mass extinction or other ecological effects. In any case following to the giant size of the Kara event touched the sedimentary rocks abundant with black shales and carbonates, which should be a result of essential atmospheric changes. The study has been supported by the Russian Science Foundation project #17-17-01080.

How to cite: Shumilova, T.: The Kara astrobleme size, age and potential paleo-ecological effects of the impact event (European Arctic Zone, Russia), EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-8523, https://doi.org/10.5194/egusphere-egu21-8523, 2021.

The Paleocene-Eocene thermal maximum (PETM; ~55.6 Ma) is one of the most pronounced and the best known of the transient hyperthermal events of the Paleogene. The PETM is characterized by global warming, a significant perturbation of the carbon cycle, and a large perturbation of the biosphere. This extraordinary event is recorded by sharp negative carbon excursions (NCIE) in both oceanic and terrestrial carbonates. The sequence of events triggering this disturbance and the source of the ¹³C-depleted carbon for the NCIE remains controversial. External perturbation such as volcanism, associated with the setup of the North Atlantic Igneous Province (NAIP), is suspected to be one of the mechanisms responsible for this abrupt climate upheaval. One proxy for investigating the possible link between the establishment of the NAIP and perturbation associated with the PETM is to study mercury (Hg) concentrations record in marine and continental sedimentary successions.

In this study, we present new high-resolution mercury and stable isotopic records from peripheral basins of the Pyrenean orogen across the PETM. The four studies sections vary from continental to bathyal deposit environment and offer the potential to evaluate how major climatic disturbances are associated with the PETM record through a continental to marine transect.

The data obtained reveal the occurrence of two main NCIEs. Based on biostratigraphy and similarity of shape and amplitude of the isotopic excursions with global records, the largest NCIE is interpreted as the PETM. This sharp excursion is preceded by another one that we interpreted as the Pre-Onset Excursion (POE), founded in some other profiles worldwide. These two NCIEs are systematically associated with important mercury anomalies, whatever the environment considered. Increase in Hg contents shows no correlation with clay or total organic carbon contents, suggesting that the influences of local processes or Hg scavenging by organic matter appear to be insignificant. These results show that multiple pulses of volcanism, probably associated with the emplacement of the NAIP, contributed to the onset and the long duration of the PETM. In addition, our study highlights the possibility to get reliable information about past extreme climate events from sedimentary successions even if deposited within active tectonic domains.

This work is financed and carried out within the framework of the BRGM-TOTAL Source-to-Sink project.

How to cite: Tremblin, M., Khozyem, H., Spangenberg, J. E., Fillon, C., Calassou, S., Grauls, A., Lasseur, E., Roig, J.-Y., Serrano, O., Guillocheau, F., Adatte, T., and Castelltort, S.: Enhanced volcanism associated to the emplacement of the North Atlantic Igneous Province during the PETM evidenced by mercury anomalies in Pyrenean foreland sections, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-12788, https://doi.org/10.5194/egusphere-egu21-12788, 2021.

Sections of the Fur formation exposed on the islands of Fur and Mors (N. Jutland, Denmark) expose well-preserved diatomites and over 140 interbedded ash layers spanning >1 Myr of the Early Eocene from the top part of the Paleocene-Eocene Thermal Maximum (PETM; 55.9 Ma). The Fur Formation is a Konzentrat-Lagerstätten with an extremely rich fish fauna as well as numerous exquisitely preserved invertebrates, vertebrates, plant material, and siliceous microfossils. Due to its peculiar bentonite record, the Fur formation also constitutes a reference for the North Sea area, recording phases of active North Atlantic Igneous Province (NAIP) volcanism. Recently, a sea-surface temperature (SST) record was derived from Tex₈₆ values for this formation, showing anomalously cool SSTs immediately after the PETM (~11–23°C, Stokke et al., 2020) while near-freezing bottom-water temperatures (BWTs) have been inferred from clumped isotopes analysis of giant glendonite crystals (Vickers et al., 2020). The section is constrained by three radiometric dates of ash layers but cyclostratigraphic analysis of the section has proved difficult due to the apparent homogeneity of the diatomite and multitude of interbedded ash layers. We performed a high-resolution analysis of the magnetic susceptibility and carbon isotopes on bulk organics (δ¹³C_org) from across the top PETM to the top of the Silstrup Mb. The magnetic susceptibility depicts all the apparent ash layers as well as additional hidden ash layers with peaks of various heights, and thus constitutes an excellent stratigraphic tool for its potential of correlation to other sections and deep-sea sites of the North Atlantic. Our δ¹³C_org record is characterized throughout by periodicities of 65 to 90 cm and 3.6 m that match well precession and short-eccentricity cycles. Long-term trends and filtered 100 kyr cycles from our record correlate very well to the recent benthic δ¹³C Cenozoic compilation, leading to an astronomical calibration of the section which spans ~1300 kyr from 55.88 to 54.6 Ma. Our calibration allows for a precise illustration of the drastic contrast between the post-PETM warm tropical SSTs/BWTs and the surprisingly cool SSTs/BWTs of the North Sea.

References

Stokke, E.W., et al., 2020, Earth and Planetary Science Letters 544, 116388.

Vickers, M.L., et al., 2020, Nature Communications 11, 4713.

How to cite: Thibault, N., Adatte, T., and Spangenberg, J. E.: Astronomical calibration of a key Early Eocene Boreal section: implications for the climate response to the North Atlantic Igneous Province, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-13017, https://doi.org/10.5194/egusphere-egu21-13017, 2021.

The Paleocene-Eocene Thermal Maximum (PETM, ~56 Ma) was the most marked climate warming event of the Cenozoic, and a potentially useful deep time analogue for understanding environmental responses to anthropogenic carbon emissions and associated warming. The response of sedimentary systems to the large-scale climate changes of the PETM are, however, still uncertain. Here, we present an extremely thick (~140 m) record of the PETM in cores from a well in the North Sea, offshore UK. In this well, a thick Paleocene-Eocene interval is developed owing to uplift of the East Shetland Platform in the late Paleocene. Carbon isotope data through this well, coupled with detailed sedimentological analysis, show that the PETM interval is contemporaneous with >200 sandstone turbidites layers. Mud deposition without turbidites dominated sedimentation below and above the PETM. These observations support previous work from other localities highlighting how climate warming during the PETM likely drove substantial changes in hydrological cycling, erosion and sediment supply. Spectral analysis of turbidite recurrence in the PETM interval suggests that the abundance of turbidites was modulated in part by ~21 kyr astronomical precession climate cycles, further emphasizing a potential climatic control on turbidite sedimentation. In detail, we note a kiloyear-scale time lag between onset of the PETM carbon isotope excursion and the appearance of turbidites in the succession, highlighting a delay between PETM carbon release and warming and the basin-wide response in sediment supply.

How to cite: Jin, S., Kemp, D., Jolley, D., Vieira, M., and Huang, C.: Large-scale siliciclastic input during the Paleocene-Eocene Thermal Maximum in the North Sea Basin, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-3731, https://doi.org/10.5194/egusphere-egu21-3731, 2021.

The Paleocene and early Eocene were periods yielding multiple hyperthermal events. The most pronounced of them was the Paleocene-Eocene Thermal Maximum (PETM), which was characterized by an abrupt increase in global temperature (5–8 °C) over a short time (20 ka). A negative carbon isotope excursion marks the onset of the PETM, which resulted in the fast injection of CO₂ into the ocean-atmosphere system, triggering global climatic changes. Geochemical, mineralogical, and sedimentological markers record the resulting increase in continental weathering. This is important, as enhanced chemical erosion influences both the CO₂ concentration in the atmosphere and ocean acidity, generating a feedback mechanism. Hence, constraining the rates and intensity of weathering response can further clarify the causes for the PETM and Eocene hyperthermals. This study focuses on the well-preserved Pyrenean foreland basin and intends to assess the continental chemical weathering response of the sediment routing system during the PETM. Clay mineralogy is a climate-sensitive proxy, which records changes in continental erosion. Therefore, clay mineral proportions will be analyzed using X-ray diffraction and major element chemistry on clay-rich samples from the entire source-to-sink system (continental to deep marine deposits). Kaolinite and smectite will be separated from the detrital clay fraction and further subjected to δ¹⁸O and δD isotopic analysis for paleoclimatic reconstruction. The combined Lu-Hf and Sm-Nd isotope systems in the clay fraction of the sediments will be used to track the evolution of chemical weathering intensity. The outcome of this project will serve to validate numerical models to understand erosion as a function of rapid climatic change. This topic is of keen interest, as the PETM and its sedimentological signal work as a natural analog for anthropogenically-induced climatic change. The project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie Grant Agreement No 860383.

How to cite: Jaimes-Gutierrez, R., Adatte, T., Puceat, E., Braun, J., and Castelltort, S.: Chemical weathering response to extreme global warming during Paleocene-Eocene Hyperthermals, Southern Pyrenees, Spain, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-12452, https://doi.org/10.5194/egusphere-egu21-12452, 2021.

The Paleogene Adriatic carbonate platform(s) existed within the Central NeoTethys (around 32 N paleolatitude) from the Danian to the late Eocene (Bartonian/Priabonian) and produced a succession of limestones up to 500 m thick, rich in larger benthic foraminifera (LBF). The Eocene sediments are widely distributed along the eastern Adriatic coast and have been studied for many years. Taking into account the climatic changes that took place within the Eocene (Early Eocene and Middle Eocene climatic optima, known as EECO, MECO), special attention was paid to the composition of shallow-marine foraminiferal assemblages. The studies reveal the following trends: (1) the alveolinid-dominated assemblages were replaced by nummulitid-dominated assemblages around the MECO; (2) the greater species and morphological diversity (spherical, ellipsoid, extremely elongated fusiform) of the alveolinid fauna was evident at the EECO; (3) the nummulitid-dominated fauna was characterized by less diversified assemblages compared to the alveolinid ones and by the co-occurrence of scleractinian corals, coralline red algae and aborescent foraminifera. The occurrence of twin embryos has been assigned to the early Eocene in the alveolinid populations, especially in Alveolina levantina and A. axiampla (in some sections, the frequency is greater than 5%), and these coalesced embryos have the same size as the single form (usually they are smaller). The LBF assemblages of Middle Eocene showed a greater frequency of doubled adult tests (Orbitolites sp., Nummulites sp.). The origin of these unusual morphologies is poorly known, usually described as the results of stressful conditions. Considering the timing of the appearance of such morphologies, temperature and associated changes in the shallow-marine environment could be the cause.

This study is carried out as part of the scientific project IP-2019-04-5775 BREEMECO, funded by Croatian Scientific Foundation.

How to cite: Ćosović, V., Španiček, J., Drobne, K., and Mrinjek, E.: The incidence of unusual test morphologies of Eocene Larger benthic foraminifera: An example of Paleogene Adriatic Carbonate Platform, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-10340, https://doi.org/10.5194/egusphere-egu21-10340, 2021.

The Paleocene-Eocene Thermal Maximum (PETM) is recognized as one of the potential analogues in the geological record for present-day global warming. The aim of the International Continental Scientific Drilling Program (ICDP) project PVOLC is to test the hypothesis that voluminous magmatism in sedimentary basins in the NE Atlantic triggered the PETM. Two ICDP boreholes are planned to core the boundary in the Limfjorden area in Denmark in 2022. PVOLC will be conducted in conjunction with IODP Exp 396 on the mid-Norwegian continental margin. The North Atlantic Igneous Province (NAIP) was is a large igneous province (5–10 million km³ magma) that coincided with both the opening of the NE Atlantic Ocean and the greenhouse conditions of the early Paleogene. The close temporal correlations suggest a possible causal relationship between the NAIP and both the climatic and tectonic changes around 56– 54 Ma. In particular, the main acme of NAIP activity occurred across the Paleocene–Eocene Thermal Maximum (PETM), an extreme hyperthermal event that represents the warmest conditions of the last 60 million years. The NAIP is among several proposed candidates for driving global warming through CO2/CH4 emissions, both by magmatic degassing and through contact metamorphism around shallow intrusions in organic rich sedimentary basins. What is needed to refine the role of the NAIP during the PETM are key sedimentary sequences that contain abundant volcanic and climatic proxies in the same section, thereby allowing a precise geochronology of events to be attained. The sediments exposed on the Fur island, Denmark, are a key sequence of PETM and post-PETM strata with little thermal overprint and hundreds of well-preserved volcanic ash layers from the NAIP. The effects of Quaternary glaciotectonism have disturbed this key stratigraphic interval at Fur, but seismic surveys indicate that undisturbed strata are found a few km to the south. The ICDP PVOLC project plan is to drill both the Paleocene-Eocene and the Cretaceous-Paleocene boundaries, hopefully recovering pristine cores suitable for high-resolution geochemical and climatic studies.

How to cite: Jones, M., Stokke, E., Planke, S., Augland, L., Svensen, H., Tegner, C., Sluijs, A., Frieling, J., Mather, T., and Huismans, R.: Coring of the Paleocene-Eocene Thermal Maximum (PETM) in Denmark: ICDP Project PVOLC, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15570, https://doi.org/10.5194/egusphere-egu21-15570, 2021.

Continental breakup between Greenland and NW Europe in the Paleogene was associated with transient massive magmatism and a global hot-house named the Paleocene-Eocene Thermal Maximum (PETM). The International Ocean Discovery Program (IODP) Expedition 396 will study the cause of this magmatism and its climate implication by drilling up to nine boreholes across the Vøring and Møre continental margins in August-September 2021. The expeditions will be conducted in conjunction with ICDP project PVOLC which plan to drill the Paleogene sequences in a more distal setting in Denmark in 2022. The NE Atlantic conjugate volcanic rifted margins are characterized by extensive break-up magmatism recorded by basalt flows, volcanogenic sediments, magmatic underplates, and intrusive complexes in sedimentary basins and the crust. Massive injection of magma into organic-rich sedimentary basins is a likely mechanism for triggering short-term global warming during the Paleocene-Eocene Thermal Maximum (PETM). A key objective of this expedition is to document the nature and explain the causes and consequences of excess magmatism during breakup as the large amount of magmatism cannot be easily be explained by passive decompressional melting of sub-lithospheric mantle with a normal potential temperature. New constraints on 1) melting conditions, 2) timing of magmatism, 3) spatial and temporal variations, 4) eruption environment, 5) sedimentary proxy data, and 6) temporal resolution of magmatism and climate change events are required to resolve current controversies. Systematic IODP drilling is a way to provide these constraints and will allow the development of a quantitatively testable framework for volcanic rifted margin formation and consequences for global climate change. New 3D seismic data collected by the industry and academia during the past few years have provided unique imaging of the basalt and sub-basalt sequences and allowed for optimal planning of the drill sites for scientific purposes. Additional holes are located along and outboard of the continent-ocean boundary to constrain the temporal evolution of the breakup magmatism. Two of the scientific drilling aims of this cruise are to core Paleogene sequences across the PETM and to drill one of the thousands of hydrothermal vent complexes to attain a proximal record of NAIP activity. This will give vital information on the proximal environmental disturbances during the NAIP emplacement.

How to cite: Planke, S., Huismans, R., Berndt, C., Gernigon, L., Buenz, S., Faleide, J. I., Jones, M. T., Svensen, H. H., Jerram, D. A., Millett, J. M., and Myklebust, R.: Mid-Norwegian continental margin magmatism and Paleogene global climate change: An overview of the upcoming International Ocean Discovery Program (IODP) Expedition 396, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15114, https://doi.org/10.5194/egusphere-egu21-15114, 2021.