Orals: Tue, 5 May, 14:00–15:45 | Room -2.62
The sea floor drill rig MARUM-MeBo is a robotic drill rig that is deployed on the sea floor in order to collect cores from sediments and hard rocks. It can be deployed from multipurpose research vessels. The first generation MeBo70 was designed to drill down to 70 m below sea floor (mbsf) and is operated for about 20 years since 2005. The second generation MeBo200 had its first deployments in 2014. So far, a maximum drilling depth of 146 mbsf was reached. In summary, we have conducted 30 research expeditions and drilled 7465 m. Core recovery rates were in average about 67 % and strongly depend on the drilled lithology. A better control on flush water circulation by using a mud mixing system will be needed to improve the drilling results especially in sandy deposits and crystalline rocks. Knowledge on the expected geology combined with a hydroacoustic survey including high resolution bathymetry in rough terrain, high resolution seismics and sub-bottom profiling are needed for safe operations and optimizing the drilling strategy. A variety of research targets were addressed during the drilling campaigns with MeBo including paleoenvironmental research, gas hydrates and associated processes like authigenic carbonate and pockmark formation, slope stability, geothermal gradient and fluid circulation as well as mafic and ultra mafic rock alteration. Next to core drilling, the sea floor drill rigs are used for bore hole logging and the installation of instrumented borehole observatories.
How to cite: Freudenthal, T.: 20 years of operational experiences with the MARUM-MeBo sea floor drill rigs: scientific applications and lessons learned, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-14426, https://doi.org/10.5194/egusphere-egu26-14426, 2026.
The SWAIS2C program examines the Sensitivity of the West Antarctic Ice Sheet to 2 degrees Celsius of warming. The central aim of SWAIS2C is to use geological archives obtained from West Antarctica to assess the state of the ice sheet during past climate states. Project partners include the International Continental Scientific Drilling Program (ICDP), and a consortium of national Antarctic programs and international collaborators.
Here we present the initial findings from SWAIS2C’s 217m-long drill core recovered during the 2025/26 field season from beneath Crary Ice Rise (CIR), West Antarctica (S 83.0267, W 172.6258; ICDP Site 5072_2_A). Drilling at CIR required a 515 m deep access hole to be melted through the ice and then the drilling of 228 m of core in permafrost conditions. Drilling was accomplished with the Antarctic Intermediate Depth Drill (AIDD) system, a modified geotechnical rig, which included hot water delivery to the cutting face. The AIDD recovered 217 m of core (95 % recovery). The core was assigned to five lithostratigraphic units based on grain size, biogenic content, and lithological sequences representing subglacial to ice-free environments. Natural gamma ray downhole logging data supports the placement of these unit boundaries. Initial biostratigraphic age estimates from the lowermost lithostratigraphic unit suggests a maximum age of middle Miocene (~17 Ma). The cyclic pattern evident in the stratigraphy provides direct evidence of a dynamic and climate sensitive WAIS from the Mid-Miocene to recent.
Successful integration of hot water drilling and the AIDD system provides a basis for future drilling beneath polar ice sheets where observations are lacking but are needed to better constrain the likely response of ice sheets like the WAIS to future warming.
How to cite: Horgan, H., Patterson, M., van de Flierdt, T., Levy, R., Dunbar, G., Kulhanek, D., Gasson, E., Grant, G., Marschalek, J., Power, P., Tetard, M., Ulfers, A., Vadman, K., Venturelli, R., Coenen, J., Heins, M., Harwood, D., and Leventer, A. and the SWAIS2C Science Team: SWAIS2C – The Sensitivity of the West Antarctic Ice Sheet to 2 degrees of Warming - Results from Crary Ice Rise. , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-15363, https://doi.org/10.5194/egusphere-egu26-15363, 2026.
In the past four decades, high latitude regions have been warming 2 to 4 times more rapidly than the global average, and their ocean and cryosphere are rapidly changing. Arctic sea-ice loss, complex Antarctic sea-ice variability, instability of the Greenland and Antarctica continental icesheets, and melting have consequence for the entire planet including sea-level rise, changing ocean currents, and impacts on polar species, ecosystems and biodiversity. The International Ocean Discovery Program (IODP) completed 8 expeditions in high latitude locations during the past ~10 years. One aim that these expeditions share is to study ocean and cryosphere responses to warm climates in the geological past to get insights into cryosphere instability thresholds in a (future) warm climate scenario. Obtaining continuous high latitude records is challenging, but even snapshot views of the past offer important insights into the interaction among climate, ocean and cryosphere (in)stability, and ecosystem responses.
On behalf of numerous collaborators, I will present an overview of what we have learned so far about ocean and cryosphere variability during warm periods of the Neogene (Miocene Climatic Optimum and Pliocene) and the Quaternary. I will discuss (preliminary) results, mostly centered on palynology, obtained from Expeditions 374 (Ross Sea) and 400 (NW Greenland) in the context of additional sedimentological and geochemical data, and link them to results from previous (I)ODP expeditions and on-going projects.
How to cite: Sangiorgi, F., Hou, S., Koene, B., Nelissen, M., Sriwichai, M., Steinsland, K., Bijl, P., Peterse, F., Kulhanek, D., McKay, R., de Santis, L., Knutz, P., Jennings, A., Hillenbrand, C.-D., and Larter, R. and the IODP Exp 374 & Exp 400 scientists: High-latitude ocean and cryosphere during warmer than present climates of the Neogene and Quaternary: a view from Antarctic and NW Greenland (I)ODP expeditions, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-22430, https://doi.org/10.5194/egusphere-egu26-22430, 2026.
SPARC (Scientific Projects using Ocean Drilling Archives) is an IODP3 programme to utilize legacy cores by large-scale research groups. Three projects (Exp. 504S, Exp. 505S, Exp. 506S) were launched in the first year, with a start date in summer or fall and will last for three years.
The North Atlantic plays a crucial role in regulating global climate due to its proximity to major ice sheets and sensitivity to changes in the Atlantic Meridional Overturning Circulation (AMOC). Over millennial and orbital timescales, the region has experienced abrupt climate shifts with significant global implications. The Exp. 506S SIGNALS (Stratigraphic InteGration of North Atlantic Legacy Sites) project aims to synthesize and integrate legacy records into a coherent, four-dimensional stratigraphic framework to provide a regional reconstruction of past climate variability on millennial to orbital timescales since the late Miocene.
SIGNALS will enhance stratigraphic correlation, refine age models, and synchronize proxy datasets for multiple legacy sites across the North Atlantic spanning a wide range of climatic and bathymetric gradients. The project will capitalize on advanced methods, including machine learning and signal correlation algorithms, to rapidly produce high-resolution data by automated processing of core images, point counting, and precise stratigraphic correlation.
SIGNALS will address methodological issues associated with estimating uncertainty in stratigraphic correlations and the limits of temporal resolution at each site given varying sedimentation rates, bioturbation, and sampling frequency. Furthermore, we will develop process models to understand how orbitally-driven climatic changes are expressed as cycles in the stratigraphic record of each site. By analyzing high-resolution geochemical and sedimentological proxies in a robust stratigraphic framework, the project seeks to reconstruct climate evolution and ocean circulation changes across the North Atlantic since the late Miocene. The project will focus on major climatic transitions and provide robust regional paleoclimate data for numerical modeling and assimilation studies. Beyond research advancements, SIGNALS will also foster collaboration by developing user-friendly computational tools, training early-career researchers, and making data publicly accessible through open repositories.
Although the exact implementation plan will not be decided until the science team has been selected, we will present objectives and general plans of Exp. 506S SIGNALS as one of the first SPARC projects.
How to cite: Seki, A., Hodell, D., Herbert, T., Obrochta, S., and Voelker, A.: Perspectives of IODP3 Expedition 506S SIGNALS - Stratigraphic InteGration of North Atlantic Legacy Sites, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-6279, https://doi.org/10.5194/egusphere-egu26-6279, 2026.
In the summer of 2024, Nam Co, one of the oldest lakes on the Tibetan Plateau, was the focus of the ICDP NamCore scientific drilling campaign aimed at reconstructing the Quaternary climate history of the region. Within this framework, the SNSF-funded DIGESTED project investigates biosphere-geosphere interactions across the entire lake system, encompassing water column conditions and deep sedimentary records. By integrating sedimentology, lake physics, biogeochemistry, and microbiology, the project seeks to assess the extent to which biological processes influence the sedimentary archive used to reconstruct paleoclimates and understand the ecological trajectory of the lake over the past million years.
We present the biogeochemical results from modern waters, recent and ancient sediments from the drill site. The water column is fully oxidized, with oxic conditions extending 8 cm below the sediment-water interface. Below this zone, microbially produced methane (supported by C and H isotopic ratios) shows a successive increase (0 to 7.8 mmol/L) to a depth of ~80 mblf. Methane is abundant in measurable quantities down to a depth of ~250 mblf, which marks a change in lithology from sand to non-calcareous mud. Biomarker ratios associated with methane cycling indicate a pronounced shift in microbial activity at this depth. Both the GDGT-0/Crenarchaeol ratio and the methane index (Zhang et al., 2011) increase sharply at and below 200 m, consistent with limited methanogenesis and methanotrophy above this boundary and substantially more active microbial processes below, despite the absence of detectable methane. This transition also coincides with changes in the composition of preserved and extractable subsurface microbial DNA. Our 16S rRNA gene sequence analyses reveal communities associated with fermentation and C1-based metabolisms below 200 m, whereas sediments above this depth are dominated by archived or transported taxa that are rarely active in such anoxic sedimentary environments.
With this study, we begin to piece together how microbial processes and their suppression, fluid migration, and paleoenvironmental conditions collectively shape the integrity of this climatic archive. A pronounced lithological and biogeochemical boundary at ~200 m separates a likely once-active methane cycling system from an overlying, energy-limited deep biosphere that permits methane accumulation and slow diffusive transport toward geological boundaries. Our ultimate goal is to disentangle the paleoenvironmental conditions leading to such strong shifts by coupling an age model with sedimentological, chemo-physical, and biological characterization of those archives.
Zhang, Y. G., Zhang, C. L., Liu, X.-L., Li, L., Hinrichs, K.-U., & Noakes, J. E. (2011). Methane Index: A tetraether archaeal lipid biomarker indicator for detecting the instability of marine gas hydrates. Earth and Planetary Science Letters, 307(3), 525–534. https://doi.org/10.1016/j.epsl.2011.05.031
How to cite: Thomas, C., Ceriotti, G., Raemy, E., Kou, Q., Bauersachs, T., Laakkonen, A., Shore, M., Adolph, M.-L., Moser-Roeggla, P., Picard, M., Schubert, C. J., Kipfer, R., Berg, J., Henderson, A. C. G., Clarke, L., Zhu, L., Wang, J., Ju, J., Haberzettl, T., and Vogel, H.: Deep subsurface shifts in microbial processes in Nam Co (Tibet) revealed by multidisciplinary investigations of an ICDP drill core, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-3499, https://doi.org/10.5194/egusphere-egu26-3499, 2026.
During the last 5 Ma (Pliocene-Holocene) the Earth’s climate system has undergone a series of marked changes, including; (i) the shift from the warm state Pliocene to the cold state Pleistocene, (ii) the evolution in frequency, magnitude and shape of glacial-interglacial cycles at the Early Middle Pleistocene Transition (~1.25-0.65 Ma), and (iii) the appearance of millennial-scale climate variability. While much of this paleoclimatic narrative has been reconstructed from marine proxy records, relatively little is known about the expressions of these major changes in continental areas and their impact on terrestrial environments and biodiversity, thus resulting in a significant knowledge gap surrounding a fundamental component of the Earth’s climate system. In the framework of the Mediterranean area, a region that is sensitive to changes in temperature and hydrological cycle, the Fucino Basin in Central Italy stands out as one of the few sites that meets the necessary requirements to fill this gap. The geophysical evidence and the stratigraphical, geochronological and multi-proxy data for multiple sediment cores acquired in recent years, indicate that the Fucino lacustrine succession (i) spans continuously for at least 4.6 Ma, (ii) is highly sensitive to climate change, and (iii) contains an outstanding number of volcanic ash layers, which facilitate an independent, high-resolution time-scale. With respect to the half-graben, wedge-shape geometry of the basin, three drilling targets were identified: MEME-1, located in the middle of the basin, would intersect the whole Quaternary infill and the upper part of the Pliocene continental sequence at ~400-500 m depth; MEME-2, which is located ca. 1.8 km west of MEME-1, where the sedimentation rate is lower, and is ~400-500 m deep, allows recovery of the entire Pliocene-Quaternary infill reaching the Messinian substratum; MEME-3 (~250-300 m depth), located for tectonics objectives on the footwall of the basin master fault and covering, though discontinuously, the lake history back to ~4.6 Ma. Through a multi-method dating approach, and a multi-proxy analysis of sedimentary physical and biogeochemical properties, the MEME project will provide a detailed record of changes in the Earth climate system and the environmental-ecological response, independent of any a priori assumptions on response times to climate forcing and feedback mechanisms. Furthermore, the Fucino sedimentary succession has enormous potential to reconstruct a uniquely comprehensive long-term, high-temporal resolution record of peri-Tyrrhenian explosive volcanism and of the post-orogenic extensional tectonics in this area of the Apennine chain.
How to cite: Giacco, B. and the MEME Team: ICDP Fucino paleolake project: the longest continuous terrestrial archive in the MEditerranean recording the last five Million years of Earth system history (MEME), EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-8013, https://doi.org/10.5194/egusphere-egu26-8013, 2026.
The Trans-Amazon Drilling Project (TADP) aims to reconstruct the Amazonian physical landscape, climate, and rivers during the Cenozoic, in parallel with the evolutionary history of the tropical forests. Scientific drilling was carried out in the western Acre Basin and the eastern Marajó Basin to recover Cenozoic sediments up to 2000 m and 1280 m depth, respectively. Multiple episodes of drill-string imprisonment hindered the achievement of target depths, none-the-less the TADP recovered an 870-m drill core (TADP-1A) in the Acre Basin (923 m depth) and a 735-m drill core (TADP-2A) in the Marajó Basin (924 depth) between June 2023 and September 2024. Each core comprises a sequence of poorly consolidated sandstones, siltstones, and mudstones representing Amazonian fluvial sedimentation during the Late Cenozoic. Sandstones and mudstones, respectively, of the Acre Basin are distinctive in their immature feldspathic composition and intense paleopedogenesis in comparison with analogous facies of the Marajó Basin. The TADP-1A core was described and sub-sampled for laboratory analyses, whereas the detailed description and sub-sampling of the TADP-2A core is scheduled for July 2026. This presentation will describe drilling operational issues, outreach activities, and initial results from ongoing geochronologic, geochemical, mineralogical, geophysical, and biotic analyses of the TADP-1A core.
How to cite: Sawakuchi, A., Fritz, S., Baker, P., Silva, C., Noren, A., Jaramillo, C., Bezerra, I., Martinez, A., and Garcia, M. D. G.: Drilling operations and initial results of the Trans-Amazon Drilling Project (TADP), EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-11871, https://doi.org/10.5194/egusphere-egu26-11871, 2026.
Hadal ocean trenches are among the least explored environments on Earth, yet they host the largest and most hazardous earthquakes. Formed at subduction zones where megathrust earthquakes and tsunamis originate, hadal trenches act as terminal sinks for sediment and carbon. Because instrumental and historical records are too short to capture the full range and recurrence of giant (Mw ≥9) earthquakes, hadal trench basins provide unique geological archives to reconstruct long-term earthquake behavior, including rare slip-to-the-trench events that generate large tsunamis. These basins also host extreme subseafloor ecosystems and play an unresolved role in Earth’s carbon cycle, making them key targets for integrated scientific ocean drilling and Earth system research.
IODP³ Expedition 503 (November–December 2025) drilled a trench-fill basin in the central Japan Trench at Site C0028 using the D/V Chikyu. Coring in five holes at water depths of up to 7,608.5 m reached a maximum depth of 178 m below seafloor (mbsf), recovering a complete trench-fill succession and providing the first continuous full record from the depositional center of a hadal trench basin. Initial results demonstrate that drilling successfully penetrated the full trench-fill sequence and its base. Lithostratigraphy documents a systematic transition from basal volcaniclastic-rich deposits to mixed detrital sediments and overlying biosiliceous oozes, reflecting basin initiation, growth, and progressive migration toward the trench axis. Structural data show increasing bedding dips and a normal-fault regime in the lowermost section, consistent with horst-and-graben formation related to bend faulting of the incoming Pacific Plate. An angular unconformity at depth, together with paleomagnetic observations and initial stratigraphic correlations to IODP and DSDP sites sampling the sedimentary cover of the Pacific oceanic crust, confirms recovery below the trench-fill base.
Event stratigraphy is exceptionally well preserved. Numerous thick turbidites, replicated between holes and tied to seismic reflectors, form a robust framework for paleoseismic interpretation. Distinct variability patterns in radiolarian fossil taxa abundances, together with frequent tephra layers, provide strong potential for high-resolution chronological control. Paleomagnetic data indicate a polarity reversal in the deepest cores, tentatively correlated with the Matuyama–Brunhes boundary (~773 ka), implying that the recovered sequence spans several hundred thousand years.
Geochemical analyses largely confirm previous results from giant piston coring during IODP Expedition 386 in 2021 down to a depth of approximately 40 mbsf. A decrease in alkalinity, previously hypothesized from shallow subsurface records, is confirmed, with significant changes in pore-water profiles observed below ~80 mbsf down to the base of the trench-fill sequence. Integrated sedimentological, mineralogical, physical property, headspace gas, and pore-water data document depth-dependent reaction zones, compaction trends, and early diagenesis linked to dynamic element cycling in the hadal subseafloor. Importantly, Expedition 503 successfully recovered high-quality core material suitable for microbiological investigations, enabling assessment of subseafloor microbial activity and its coupling to geochemical processes.
Together, these initial results demonstrate that hadal trench basins preserve long, continuous archives of tsunamigenic megathrust behavior and associated biogeochemical processes, opening new perspectives on earthquake recurrence, geohazards, and carbon cycling along subduction zone systems.
How to cite: Strasser, M., Ikehara, K., and Maeda, L. and the IODP3 Expedition 503 Scientists: Recovering the Long-Term Record of Subduction-Zone Tsunamigenic Slip and Element Cycling in a Hadal Trench Basin at the Japan Trench: Initial Results of IODP³ Expedition 503, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-4209, https://doi.org/10.5194/egusphere-egu26-4209, 2026.
The NEPTUNE (Noto Peninsula Earthquake Drilling Project for Understanding Fluid Triggered Slip Events) initiative aims to elucidate the mechanisms underlying the 2024 Noto Peninsula Earthquake (January 1st, 2024: Mw 7.6), a major seismic event characterized by a complex rupture sequence across multiple fault segments. This earthquake began with a slow initial rupture that evolved into a dynamic rupture extending over 150 km, highlighting the critical need to understand the interactions between fault behavior and pre-seismic crustal processes.
A central focus of the project is the influence of elevated pore fluid pressure, which promotes fault slip by lowering effective normal stress. The migration and accumulation of fluids—likely derived from the mantle—have been identified as key factors that triggered the preceding earthquake swarms. Geochemical signatures, including high ³He/⁴He ratios, support this interpretation. The event further demonstrated that rupture propagation was facilitated by both segmented fault structures and fluid-induced weakening.
The project plans to drill from the coastal region of the Noto Peninsula, targeting the fault plane of the 2024 earthquake. Core objectives include retrieving fluid, gas, and rock samples to investigate fluid sources, chemical interactions, and fault zone microstructures. Long-term monitoring of fluid and gas behavior near the fault zone is also planned to track post-seismic evolution and enhance preparedness for future seismic events.
Three primary research areas are emphasized:
- Observing fluid migration and pressure fluctuations through direct sampling, numerical simulations, and seismic analysis.
- Characterizing the origins of fault zone rocks and fluids to evaluate their role in earthquake generation.
- Assessing mineralogical and geochemical transformations within the fault zone to understand their impact on fault strength and slip behavior.
The outcomes of NEPTUNE are expected to deepen our understanding of earthquake nucleation, particularly the transition from swarm activity to rapid fault rupture. Aligned with the geohazard priorities of the ICDP Science Plan 2020–2030, the project aims to improve forecasting capabilities for intraplate seismic hazards. In addition, the project includes a complementary proposal for Land-to-Sea (L2S) drilling, aiming to access and study the tsunami-generating fault system from an onshore platform, to be submitted to IODP.
How to cite: Otsubo, M. and the NEPTUNE Proponents: NEPTUNE Project: Exploring Fluid-triggered Slip Mechanisms through Scientific Drilling in the Noto Peninsula, Japan, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-20515, https://doi.org/10.5194/egusphere-egu26-20515, 2026.
Understanding the chemical and physical processes governing the formation and evolution of the Earth’s continental crust is fundamental for the Earth system and other planets. The upper crust is accessible to direct geological observation and sampling, but deeper portions, especially the lower crust and the crust–mantle transition zone (“Moho”) are usually beyond reach. The lower continental crust (LCC) is one of the most important, but also most enigmatic regions of Earth’s lithosphere and its composition and physical properties are strongly debated. Here we report some of the initial results from the first phase of the ICDP-funded “Drilling the Ivrea-Verbano zonE” (DIVE) project (site 5071_1) in Val d’Ossola (northern Italy). From October 2022 to April 2024 two boreholes of respectively 578.5 (Ornavasso, 5071_1_B) and 909.5 m (Megolo, 5071_1_A) depth were drilled using continuous diamond double tube wireline coring. During and after drilling, geophysical logs were acquired, providing natural and spectral gamma ray, magnetic susceptibility, electrical resistivity (SPR and DLL), spontaneous potential, sonic, acoustic and optic televiewer data, complemented by multi-sensor core logging data (with focus on density) acquired in the core repository of the BGR in Berlin-Spandau (Germany). In addition, continuous real-time mud gas logging provides evidence of varying gas mixtures including He, H2, CH4, and CO2, indicating diverse fluid sources and possible microbial activities in the deep crust.
The two drillholes sampled two fundamentally different compositions of the lower continental crust: the first hole (5071_1_B) drilled the upper part of the lower continental crust and mostly consists of metasedimentary rocks and a few amphibolites. The second hole (5071_1_A) drilled the lowermost continental crust and mostly captured a variety of garnet and/or orthopyroxene bearing gabbroic rocks with intercalations of garnet granulite facies metasediments, pyroxenite, and intrusive gabbronorite including frequent pseudotachylites. Combining multi-sensor core-logging data with petrophysical information and whole rock geochemical data provides mineral modes of the drilled cores, which can be used to calculate densities and seismic velocities. These calculations together with direct observations of drilled rock types indicate that the lowermost part of the Ivrea Verbano Zone continental crust is enriched in garnet.
Bulk compositions of the two different drillholes of the lower crust show fundamental differences. 5071_1_B is felsic, similar to global upper crust, while 5071_1_A is dominantly mafic, and similar to the more depleted estimates of global lower continental crust. There is about a 10-fold difference in radiogenic heat producing and volatile elements between the two drillholes, and highly variable thermal properties. Extrapolating the observed datasets beyond the scale of the drillholes suggests both intrinsic and structural variability caused anisotropy of the continental lower crust.
How to cite: Müntener, O., Hetényi, G., Andrew, G., Ziberna, L., Zanetti, A., Pistone, M., Giovanelli, D., and Venier, M. and the The DIVE Drilling Project Science Team: The variability of lower continental crust: Initial and advanced results from the ICDP DIVE project, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-16927, https://doi.org/10.5194/egusphere-egu26-16927, 2026.
The Tibetan Plateau (TP), often referred to as the “Third Pole” and “Asian Water Tower”, serves about two billion people downstream with its water resources; thus, investigations of past climate changes on the TP have significant socio-economic implications for both the scientific community and governmental concerns. Numerous lakes on the plateau provide valuable archives to carry out paleoenvironmental change studies on different time scales by drilling sediment cores. With the support of the ICDP (NamCore project, Expedition 5073) and other funding, we accomplished a drilling campaign in a high-altitude, deep lake (Nam Co, 4718 m) on the Tibetan Plateau in the summer of 2024. In total, ~950 m of cores was recovered from seven holes at one site, with a deepest drilling depth of 510 m b.l.f., making NamCore a great success among ICDP lake drilling projects in the past several decades with respect to its altitude and maximum penetration depth. These achievements enable us to study past climate changes in this area potentially back to ~1 Ma and their linkages with other regions globally. Three core opening and sampling parties of the NamCore project have been organized in Beijing, where the cores were stored, to complete the splitting of all cores. Core descriptions, magnetic susceptibility scanning of the entire sequence combined with other analyses (e.g., grain size, organic/inorganic carbon content, biomarkers and pollen, etc.) on core catcher samples have revealed sediment variations, which can distinctly show the fluctuations between glacial and interglacial cycles, although the chronology using various approaches is still challenging. The results show four major lithologies throughout the drilled cores including calcareous mud, non-calcareous mud, sand and calcareous mud with ferric staining. Calcareous mud dominates the upper ~120 m and ferric-stained mud mainly appear in the sections deeper than ~320 m. Many sand layers with different thickness occur in the entire sequence but mostly in the middle part. Nothing has been retrieved in a section greater than 30 m in thickness in the lower part, which probably indicates a remarkable change in the sedimentary environment associated with a glacial period. Time series analysis on the magnetic susceptibility data shows two prominent cycles at 10.1 m and 21.4 m, which potentially correspond to the orbital precession and obliquity forcing of 21 ka and 41 ka, respectively. This cyclostratigraphic approach will be helpful to constrain the chronology and, by comparison with stalagmites in monsoonal areas and ice cores in polar regions, plays an important role in discovering the different drivers of climate change from low and high latitudes. However, more efforts are still needed to obtain absolute ages to establish a precise timeframe for these cores.
How to cite: Wang, J., Adolph, M.-L., Cidan, Z., Zhu, L., Haberzettl, T., Vogel, H., Clarke, L., Henderson, A., Spiess, V., Ju, J., Ma, Q., Kou, Q., and Daut, G.: Scientific Drilling on the Third Pole: achievements of the highest ICDP lake drilling project on the Tibetan Plateau (Nam Co, 4718 m.a.s.l), EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-7514, https://doi.org/10.5194/egusphere-egu26-7514, 2026.
Ostracods from sediment cores of the ICDP NamCore drilling project were analysed to document their distribution, abundance, and preservation, and to explore their potential for reconstructing past lacustrine conditions on the central Tibetan Plateau. Selected core catcher samples covering sediment depths from ~8 to 470 m were investigated for their microfossil content. Sediment samples (10–15 g each) were wet-sieved at 63 µm and 200 µm, and the >200 µm fraction was examined under a stereomicroscope. Ostracods were assessed semi-quantitatively and assigned to five abundance categories (absent, 1-10, >10, >100, >1000 valves per sample). Preservation states were evaluated qualitatively, and taxonomic identifications were based on established regional faunal keys.
Ostracods represent the only fossils observed in the sand-sized fraction of the analysed samples. Their abundance varies strongly, ranging from complete absence to more than 1000 valves per sample, with approximately half of the samples containing more than 100 valves. Preservation is generally good, although weakly etched, fragmented, compacted, or deformed valves occur, particularly below ~180 m core depth. Assemblages are of low diversity, with a maximum of five species per sample. At least six ostracod taxa were identified, including Leucocytherella sinensis, ?Leucocythere dorsotuberosa, ?Leucocythere postilirata, Ilyocypris ?bradyi, a smooth Ilyocypris species of uncertain taxonomic status, and juvenile Candona spp. The taxonomic assignment of ?Leucocythere dorsotuberosa and the smooth Ilyocypris species is the subject of ongoing investigations.
Variations in ostracod abundance, species level assemblage composition, and variable preservation suggest changes in depositional and post-depositional conditions through the core. While the presence of ostracods throughout most sections is consistent with predominantly lacustrine settings, intervals with low abundances or poor preservation may reflect a range of factors, including lake-level changes, sedimentation dynamics, or taphonomic overprinting. Further quantitative analyses, improved taxonomic resolution, and integration with independent proxies are required to refine palaeoenvironmental interpretations.
How to cite: Schmitz, O., Frenzel, P., Pint, A., Adolph, M.-L., Clarke, L., Henderson, A., Vogel, H., Wang, J., Zhu, L., Höhle, M., Wrozyna, C., and Haberzettl, T.: Ostracods from sediment cores of the ICDP NamCore drilling project provide insights into long-term lacustrine evolution on the Tibetan Plateau, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-13464, https://doi.org/10.5194/egusphere-egu26-13464, 2026.
A central objective of the NamCore ICDP project is to understand Quaternary biotic dynamics—specifically species diversity, distribution, and evolution—in relation to Asian monsoon variability and orbitally driven climate change. Lacustrine ostracodes are therefore ideal indicators to assess (1) whether Nam Co served as a glacial refugium for cold-adapted species during glacial periods, (2) how biota responded to glacial–interglacial environmental transitions, and (3) whether the lake exhibits a high ecological resilience to environmental change.
To address these objectives, a multi-scale analytical approach was applied. Ostracode valve analyses were conducted on 43 core catcher samples spanning depths from 8 m to 470 m b.l.f., corresponding to a stratigraphic resolution represented by intervals of 3–35 m, to provide an overview of broad-scale changes in ostracode distribution and abundance. To obtain higher-resolution data on species distribution and morphological variability, additional samples from core sections within the upper 33 m b.l.f. were analyzed at 16 cm intervals. Morphometric analyses of valve outline shape and size are intended to identify either gradual or abrupt changes in morphological variability. Environmentally driven morphological responses are expected to manifest as gradual shifts in size and/or shape, whereas re-colonization from other lakes may produce distinct morphological signatures, resulting in discontinuous variation in size or shape.
Preliminary results indicate that ostracode abundance and species composition are highly variable, with ostracodes absent below 470 m b.l.f. In total, ten species were identified, with a maximum of five species per sample. Generally, samples from the uppermost 30 m contain four species that are absent in the lower sections of the record. Although Leucocytherella sinensis and ?Leucocythere dorsotuberosa represent the most abundant taxa, no species occurs continuously throughout the sedimentary record.
Detailed analyses of species composition, combined with morphometric investigations, are expected to elucidate whether the discontinuous ostracode distribution pattern reflects repeated lake colonization events associated with, e.g. glacial–interglacial cycles. Such findings would have significant implications for understanding the role of the Tibetan Plateau as a biodiversity refugium during Quaternary climate oscillations and for reconstructing paleoenvironmental conditions from ostracode assemblages in high-altitude lake systems.
How to cite: Wrozyna, C., Hoehle, M., Adolph, M.-L., Frenzel, P., Schmitz, O., Clarke, L., Henderson, A. G., Vogel, H., Wang, J., Zhu, L., and Haberzettl, T.: Lacustrine ostracodes from Nam Co (Tibetan Plateau) indicate biotic responses to Quaternary climate change (NamCore ICDP project), EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-5230, https://doi.org/10.5194/egusphere-egu26-5230, 2026.
The mineral abundance, their properties and geometrical arrangement on small spatial scales directly affect the physical characteristics of the continental crust at large scales. Consequently, the mineral assemblages determine to a large extent how geophysical methods respond to these rocks. Determining the mineral volume fractions is an essential first step for modelling and interpreting geophysical data, constraining crustal structure, and understanding the evolution of the Earth’s lithosphere. In this study, we develop a Bayesian inversion framework that integrates petrophysical information from downhole well logs and multi-sensor core logging data with X-ray fluorescence (XRF) data to estimate continuous mineral fraction profiles along two ICDP-DIVE boreholes (Greenwood et al. 2026) drilled through the exhumed lower continental crust of the Ivrea–Verbano Zone (IVZ) with almost 100% core recovery. The framework involves two schemes: (1) an overdetermined inversion of relative sparse XRF oxide weight fraction data from powdered rock samples combined with core density logs, and (2) a severely underdetermined inversion of potassium, magnetic susceptibility, and core density logs, conducted by groups derived from a cluster analysis of these logs. The latter scheme is constrained by the first scheme, which allows to retrieve a continuous mineral fraction estimates along both boreholes from the limited number of 3 petrophysical logs. An ensemble Markov Chain Monte Carlo algorithm (Cheng et al. 2022) is adapted to recover the posterior mineral fraction distributions while quantifying uncertainties. An essential input is the prior knowledge of the minerals present and their chemical formula, which may require supplementary measurements, especially for minerals such as amphibole, whose chemical formula is difficult to determine. The results show that the XRF Oxide–density inversion approach provides robust mineralogical estimates that are consistent with independently obtained modal estimates from section observations. The constrained inversion of the petrophysical logging data successfully captures mineral fractions across most lithologies despite the underdetermined nature of the problem. The study demonstrates that combining XRF-derived oxide fractions with continuous downhole and core logging data within a Bayesian framework provides a powerful approach for obtaining quantitative, mineral fractions in a range of lower crustal lithologies.
Cheng, L., Jin, G., Michelena, R., & Tura, A. (2022). Practical Bayesian Inversions for Rock Composition and Petrophysical Endpoints in Multimineral Analysis. SPE Reservoir Evaluation & Engineering, 25(04), 849–865. https://doi.org/10.2118/210576-PA
Greenwood, A., Venier, M., Hetényi, G., Ziberna, L., Heeschen, K., Pacchiega, L., Lemke, K., Dutoit, H., Bonazzi, M., Degen, S., Li, J., Secrétan, A., Trabi, B., Tholen, S., Lefeuvre, N., Auclair, S., Mariani, D., Del Rio, M., Černok, A., Bhattacharyya, A., Narduzzi, F., Mansouri, H., Urueña, C., Beltrame, M., Hawemann, F., Velicogna, M., Toy, V., Dominique, J., Longo, A., Tonietti, L., Barosa, B., Brusca, J., Nappi, N., Gallo, G., Esposito, M., Diana, S. C., Bastianoni, A., Eckert, E. M., Confal, J. M., Pondrelli, S., Piana Agostinetti, N., Tertyshnikov, K., Caspari, E., Truche, L., Wiersberg, T., Baron, L., Giovannelli, D., Pistone, M., Zanetti, A., Müntener, O. (2025): Drilling the Ivrea-Verbano zonE: DIVE 1 – ICDP Operational Report, Potsdam: GFZ Data Services, 109 p. doi:10.48440/ICDP.5071.001
How to cite: Li, J., Secrétan, A., Degen, S., Caspari, E., Greenwood, A., Venier, M., Lemke, K., Ziberna, L., Hetényi, G., and Müntener, O.: Integrating Petrophysical Logging and XRF Data for Mineral Fraction Estimation of Lower Crustal Rocks from the ICDP-DIVE Project using a Bayesian Inversion Framework, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-11216, https://doi.org/10.5194/egusphere-egu26-11216, 2026.
As part of a multidisciplinary effort to characterize the deep continental crust, two scientific boreholes were drilled in the Ivrea Verbano Zone (IVZ, Western Alps, Italy), one of the few near-complete continental crustal sections exposed on Earth's surface (Pistone et al. 2020). The boreholes were drilled within the Drilling the Ivrea Verbano ZonE (DIVE) project, supported by the International Continental Scientific Drilling Program (ICDP-5071; Li et al. 2024; https://gfzpublic.gfz.de/pubman/item/item_5037328) . Among various well log measurements, time-domain induced polarization (TDIP) logs with two electrode spacings (16″ and 64″) were collected in both wells, from which chargeability data is inferred. The boreholes intersect a wide range of lithologies hosting sulfides and oxides, either disseminated or concentrated along veins and fractures, which represent potential sources of chargeability. A set of eleven samples from these boreholes were analyzed using both scanning electron microscopy (SEM) and micro-computed tomography (μCT). The following mineralogical and microstructural characteristics have been evaluated so far: the type and abundance of metallic minerals (expressed as volume and area fractions); the perimeter-to-area and surface-to-volume ratios and the preferred orientation of these conductive phases. These parameters were compared to the TDIP response signal at the corresponding depths of the borehole, resulting in the following findings:
i) Borehole chargeability is not necessarily proportional to the abundance of metallic minerals;
ii) The total surface area (which is high for fine grain sizes) plays a dominant role over the total volume fraction of metallic minerals;
iii) The shape preferred orientation of conductive phases appears to be a key factor influencing the measured chargeability;
iv) The presence of other mineral phases, such as graphite, may mask or amplify the response of metallic minerals depending on their structural relationship.
While no deterministic relationship has been identified at this stage, this work outlines a potential path to improve the interpretation of TDIP data in mineralized systems and to define complementary yet efficient tools for assessing the economic potential of mineral deposits.
References
Li, J., E. Caspari, A. Greenwood, et al. 2024. “Integrated Rock Mass Characterization of the Lower Continental Crust Along the ICDP‐DIVE 5071_1_B Borehole in the Ivrea‐Verbano Zone.” Geochemistry, Geophysics, Geosystems 25 (12): e2024GC011707. https://doi.org/10.1029/2024GC011707.
Pistone, Mattia, Luca Ziberna, György Hetényi, Matteo Scarponi, Alberto Zanetti, and Othmar Müntener. 2020. “Joint Geophysical‐Petrological Modeling on the Ivrea Geophysical Body Beneath Valsesia, Italy: Constraints on the Continental Lower Crust.” Geochemistry, Geophysics, Geosystems 21 (12): e2020GC009397. https://doi.org/10.1029/2020GC009397.
How to cite: Ventola, I., Caspari, E., Greenwood, A., Hawemann, F., Venier, M., and Virginia, T.: Investigating Borehole TDIP Response in the Ivrea-Verbano Zone (ICDP-DIVE project):Linking Chargeability to Mineral Distribution from SEM and MicroCT Data, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-20662, https://doi.org/10.5194/egusphere-egu26-20662, 2026.
The mobility of sulphur and chalcophile metals through the lithosphere remains poorly constrained, yet it is likely to have a significant impact on metal budgets and the localisation of ore systems that underpin the supply strategic commodities for the energy transition.
Increasing evidence suggests that sulphur and chalcophile metals can be redistributed via multiple, potentially overlapping processes, including sulphide melt migration, fluid-mediated transport, partial melting, and deformation-assisted remobilisation. These mechanisms operate across a wide range of pressure-temperature conditions and may decouple metal transport from large-volume magmatic fluxes, producing complex metal redistribution patterns within the lithosphere.
In this framework, deep mafic-ultramafic cumulates in lower crustal zones act as major reservoirs and transfer hubs where sulphide melts can sequester a large fraction of the metal budget, while being episodically mobilised within melt-bearing cumulate frameworks, enabling upward transfer to upper‑crustal levels (i.e Holwell et al. 2022). A complementary mechanism for enriching and moving sulphur and copper is provided by devolatilization and wall-rock assimilation. Fluids can already effectively mobilise sulphur and copper under subsolidus conditions, enhancing mobilisation that may have already accompanied partial melting and produce Cu-rich sulphide droplets that can attach to fluid bubbles (i.e Blanks et al. 2020) or carbonate melt droplets (i.e Cherdantseva et al. 2024) which can be transported buoyantly within silicate melt (i.e Virtanen et al. 2021). Deformation potentially introduces an additional mechanism of redistribution, which is highly relevant for interpreting sulphide signatures in deep crustal rocks, and metamorphism commonly overprints ore systems, creating favourable conditions for further mobilization of critical metals (i.e Cugerone and Cenki 2025).
Newly acquired continuous drill core from the Ivrea-Verbano Zone provides an exceptional opportunity to investigate these processes in a well-constrained lower-crustal setting. The core samples mafic and ultramafic lithologies across documented igneous, metamorphic, and structural domains, allowing sulphide occurrence, texture, and chemistry to be examined in their primary context, while also distinguishing deep-crustal magmatic processes from later deformation- or fluid-assisted remobilisation.
Borehole 5071_1_A is dominated by gabbroic lithologies, with intercalations of granulite-facies metasediments and pyroxenites, as well as intrusive gabbronorites. We combine (i) XRF elemental mapping on the flat split core surfaces to track core-scale variations and identify sulphide-rich intervals and their structural/lithological controls, with (ii) SEM-EDS analyses to characterise sulphide mineralogy and (iii) LA-ICP-MS trace-element analyses of the major sulphide phases to constrain phase-dependent trace-element budgets and variations among various host lithologies as well as different textures. The sulphide assemblage is dominated by Fe-Ni-Cu sulphides (pyrrhotite-pentlandite-chalcopyrite), occurring both as disseminated interstitial grains and as foliation- and fracture-related networks associated with localised deformation and late-stage fluid pathways. Across these textural populations, trace-element systematics display different variations consistent with sulphide-silicate equilibration as well as later stage remobilisation.
By linking centimetre-scale elemental maps from continuous core to micro-analytical sulphide fingerprints, the ICDP-DIVE record allows us to advance the exploration and resource assessment for critical raw materials in complex crustal systems.
How to cite: Venier, M., Caruso, S., Fiorentini, M., Müntener, O., Ziberna, L., and Toy, V. and the DIVE Science Team: Lower continental crust sulphides from the Ivrea-Verbano Zone (ICDP-DIVE project 5071): textures, trace-element chemistry and mobility, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-22443, https://doi.org/10.5194/egusphere-egu26-22443, 2026.
How can rocks obtained by scientific drilling increase our understanding of deformation, stress, and strength in one of Earth’s classic collisional orogenic belts? By integrating scientific drilling data with high-resolution laboratory measurements, this study presents a combined structural, mineralogical and geomechanical characterization of the Scandinavian Caledonides, based on data from the COSC-2 borehole acquired during the ICDP logging campaign in 2022 . From the surface to approximately 1200 m depth, the borehole intersected an extensive Early Phanerozoic sedimentary succession, dominated primarily by wacke, shale and siltstone. Beneath this succession, extending to 2276 m, lies a crystalline basement comprising a volcanic sequence, including porphyry, gabbro and gabbroid rocks, intruded by dolerite dykes. The contact between the sedimentary succession and the crystalline basement is relatively undisturbed, with a thin regolith covering the altered top of the porphyry.
A key objective of our study is to investigate the physical properties and in-situ stress state of the COSC-2 rocks using laboratory tests on selected core samples. Specifically, we examine how stress magnitudes vary with depth, which stress regime dominates the area, how rock stiffness varies with lithology, mineralogy, and depth, and whether laboratory-derived elastic properties are consistent with downhole sonic log measurements (Vp and Vs). To address these questions, a suite of laboratory measurements was conducted on 19 core samples, including Brazilian tensile strength (BTS), uniaxial compressive strength (UCS), P- and S-wave velocities, Poisson’s ratio, Young’s, bulk, and shear moduli, grain and bulk density, and quantitative mineralogical analyses using X-ray diffraction (XRD) and electron microprobe analysis (EPMA). Our findings show that crystalline rocks exhibit in general a higher stiffness and compactness, reflected in elevated wave velocities and elastic moduli, combined with greater densities and lower porosity resulting in greater mechanical strength, both in compression and tension loading. This behaviour is reflected in specific samples, which record some of the highest BTS and UCS values. In contrast, three samples in doleritic and gabbroic rocks display unexpectedly low BTS values (19–20 MPa) and UCS values (180–211 MPa) compared to the other crystalline basement samples. Analysing the mineralogical composition, we found the presence of primary and secondary phyllosilicates in these rocks, which likely weaken the rock fabric and can be responsible for the reduced strength. In contrast, the overlying sedimentary rocks exhibit lower stiffness and strength but greater variability largely controlled by porosity and internal heterogeneity.
Of course, such geomechanical properties are also controlled by the presence of microcracks, open and cemented veins, mineral alignment and the precipitation of secondary minerals reflecting enhanced fluid flow and fluid-rock interaction processes. Especially the occurrence of secondary mineral phases identified through XRD and EMPA further reveal a complex tectono-metamorphic history. Together, these findings provide a solid framework for geomechanical modelling and advance our understanding of the evolution of collisional orogens.
How to cite: Pierdominici, S., Lopera Restrepo, A. P., Kottkamp, W., Schleicher, A. M., Wilke, F. D. H., and Schmitt, D. R.: The influence of geomechanical properties on rock strength in the ICDP COSC-2 borehole, at Are, Sweden, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-5610, https://doi.org/10.5194/egusphere-egu26-5610, 2026.
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.
In its third season, the SWAIS2C project targeted the second drilling location Crary Ice Rise Site 1 (CIR), a grounded ice sheet upstream the Ross Ice Shelf. After hot water drilling through ~516 m of ice, rotary coring retrieved a sediment succession of 228 m length comprising different lithological units.
The LIAG Institute for Applied Geophysics and the German Helmholtz Centre for Geosciences (GFZ) are in charge of geophysical downhole logging operations and retrieved the first such dataset below grounded ice. The spectrum gamma radiation (SGR) tool records the natural radiation and its components – the K-, Th-, and U-concentration – of the surrounding sediments. The data indicate distinct boundaries between the main lithological units, but minor variations and ratios of the measured elements indicate smaller differences within the units. Particularly in transitions between major units, patterns in the data may reflect changing paleo-environmental conditions. This data set will be valuable for the ongoing project as it is an in-situ, continuous record of drilled sediment succession with high accuracy depth measurements.
We give a brief overview of the SWAIS2C project, focus on the downhole logging data measured as part of the project and relate the results to other data sets from below/around the Ross Ice Shelf.
How to cite: Ulfers, A., Horgan, H., Patterson, M., Dunbar, G., Kulhanek, D., Levy, R., van de Flierdt, T., Pierdominici, S., and Zeeden, C. and the SWAIS2C Science Team: Characteristics of spectrum gamma radiation (SGR) data from geophysical downhole logging in the SWAIS2C project – West Antarctica , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-23159, https://doi.org/10.5194/egusphere-egu26-23159, 2026.
The Middle Miocene represents one of the warmest intervals in Earth’s recent geological history. Understanding the climate dynamics of this period can provide valuable insight into how the climate system may respond to future anthropogenic forcing. The study of tropical regions during the Miocene is particularly important, because these environments are underrepresented in climate records. Since the Miocene, Australia’s climate has undergone substantial changes driven by the northward drift of the continent, its collision with Southeast Asia, and the associated reorganisation of oceanic circulation around the Maritime Continent. Northern tropical Australia is presently influenced by a monsoonal system that forms part of the broader Asian Monsoon; however, the Australian Monsoon remains poorly understood, particularly with respect to its onset and variability. Investigating monsoon dynamics across different climatic states in this region may therefore improve our understanding of how large-scale circulation patterns could evolve under anthropogenically driven climate change. As a result of persistent arid conditions and lack of tectonic subsidence, evidence of fluvial and lacustrine activity has been destroyed, meaning terrestrial records of palaeoclimatic change in Australia are sparse. This study focuses on a marine core: Ocean Drilling Program (ODP) Hole 1195B on the Marion Plateau. Hole 1195B preserves an erosional and oceanographic record extending back to ~21 Ma and provides an opportunity to examine links between climate variability and continental weathering since the Middle Miocene.
This study employs XRF core scanning, GDGT biomarker analysis, and elemental analysis using ICP-OES. The results indicate that the highest delivery of clastic material to the Marion Plateau occurred during the Miocene Climatic Optimum (~17 Ma), coinciding with peak sea surface temperatures. The most pronounced cooling is observed between 11 and 9 Ma and was accompanied by significant changes in sediment input to the site. These changes were likely associated with shifts in Coral Sea circulation, potentially reflecting a strengthening of the East Australian Current. Notably, this regional response occurs ~2 Myr after the global cooling event observed elsewhere at ~13 Ma, suggesting that tropical climate systems may respond independently, or with some delay, in comparison to global climate perturbations. This highlights the importance of understanding climate dynamics in the tropics when considering potential future responses to anthropogenic climate change.
How to cite: McGanity-Smith, B., Clift, P. D., and Petrick, B.: Sediment cycling on the Marion Plateau since the Miocene, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-10351, https://doi.org/10.5194/egusphere-egu26-10351, 2026.
Half-precession cycles (HPs), first identified in the 1980s, have been increasingly recognized as an important driver of tropical hydroclimate variability during the Quaternary. However, continuous long-term proxy records capturing their imprint on monsoon systems remain scarce. Here, we investigate the presence and evolution of HPs signals in a high-resolution inorganic geochemical record from ODP Site 663 (Eastern Equatorial Atlantic). This record provides a continuous perspective on West African Monsoon (WAM) variability over the last 1.2 Myr, spanning the Mid-Pleistocene Transition (MPT). Our results indicate that WAM variability during the MPT does not exhibit clear glacial–interglacial pacing. While this contrasts contemporaneous records from the Mediterranean and North Africa, the influence of the WAM becomes more pronounced after ~600 kyr, with intensified interglacial conditions and weaker glacial phases. In contrast, HPs show a stronger imprint on monsoon variability after the MPT, particularly during interglacial intervals. These findings are consistent with runoff records from the tropical American ICDP sites, suggesting a coherent low-latitude hydroclimate response. We propose that modulation of the Atlantic Meridional Overturning Circulation may provide a mechanistic link between HPs forcing, West African Monsoon variability, and tropical American precipitation.
How to cite: Martinez-Abarca, R., Ulfers, A., Zeeden, C., Westerhold, T., Vinnepand, M., De Vleeschouwer, D., Röhl, U., and Kaboth-Bahr, S.: Half-precession modulation of the West African Monsoon and possible links to continental hydroclimate records since the Mid-Pleistocene Transition., EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-21573, https://doi.org/10.5194/egusphere-egu26-21573, 2026.
The Trans-Amazon Drilling Project (TADP) provides a unique opportunity to investigate subsurface light-hydrocarbon dynamics in Amazonian sedimentary basins through the integration of continuous real-time gas monitoring during drilling, discrete gas sampling from sediment cores, and laboratory incubation experiments. This study combines gas geochemical data from Cenozoic sediments of the Acre Basin in western Amazonia and the Marajó Basin in eastern Amazonia, to characterize the occurrence, composition, origin, migration of light gaseous hydrocarbons, and potential microbial production of methane (CH4), within continental siliciclastic successions, contributing to a refined understanding of subsurface carbon cycling.
In the Acre Basin, drilling penetrated a 923-m-thick sedimentary sequence dominated by interbedded claystones, siltstones, and sandstones. Continuous online gas analysis (OLGA) revealed CH4 as the dominant hydrocarbon throughout the drilled profile, accompanied by recurrent detections of ethane (C2H6), propane (C3H8), iso-butane (i-C4H10), and n-butane (n-C4H10). Elevated concentrations of CH4, C2H6, and C3H8 were preferentially associated with sandstone and siltstone layers sealed by claystones, indicating stratigraphic trapping of migrated gas. Bernard parameter values (CH4/(C2H6+ C3H8)) range from 2 to 1904, reflecting strong compositional variability and mixing between gas sources. Carbon isotopic signatures of CH4 (δ¹³C- CH4 between −35‰ and −25‰ VPDB) indicate a dominant thermogenic contribution.
In the Marajó Basin, continuous gas monitoring during drilling to 924.3 m depth revealed higher? CH4 concentrations than in the Acre Basin with a general increase toward greater depths. Heavier hydrocarbons (C2–C4) show co-occurring concentration maxima indicating stratigraphically discrete gas migration and accumulation. CH4 carbon isotopic compositions document a clear vertical transition in gas origin, from microbial hydrogenotrophic methanogenesis in the upper 250 m (δ¹³C- CH4 between −80‰ and −60‰), to mixed microbial–thermogenic gas between 250 and 300 m depth, and dominantly thermogenic gas below 300 m depth (δ¹³C- CH4 approaching −35‰), coinciding with increased C2–C4 concentrations.
Laboratory incubation experiments conducted on core sediment samples from both basins under anoxic conditions reveal a progressive increase in CH4 concentrations over time, indicating active microbial methanogenesis. Incubation results show higher CH4 yields in deeper samples, suggesting that, despite the strong influence of migrated thermogenic gas at depth, in situ microbial CH4 production also contributes to the subsurface methane pool and is modulated by depth, substrate availability, and redox conditions.
Overall, the integrated results demonstrate that light hydrocarbon distributions in both basins are governed by the interaction between upward migration of thermogenic gas from deeper sources, stratigraphic trapping in permeable units sealed by fine-grained sediments, and active microbial processes identified through incubation experiments. The combined use of real-time gas monitoring, isotopic analyses, and incubation experiments provides a robust framework for disentangling gas origin and transformation processes, offering new insights into subsurface carbon cycling in Amazonian sedimentary basins.
How to cite: Martinez, A., Oliveira Sawakuchi, A., Oliveira Sawakuchi, H., Bertassoli Junior, D. J., Wiersberg, T., Tsai, S. M., Azevedo Bezerra, I. S., Noren, A., Guizan Silva, C., Fritz, S., and Baker, P. A.: Characterization of light hydrocarbons in subsurface Cenozoic sediments of western and eastern Amazonia drilled by the Trans-Amazon Drilling Project (TADP), EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-13841, https://doi.org/10.5194/egusphere-egu26-13841, 2026.
The use of low-enthalpy geothermal heat is rapidly expanding, especially in densely populated urban areas, to ensure energy security and sovereignty, achieve sustainability goals, and combat climate change. The TU Delft Campus in the Netherlands hosts a 2200-m deep geothermal doublet within a lower Cretaceous clastic, fluviodeltaic reservoir, complemented by heat storage in aquifers between 123 and 284 m depth. In June 2024, the ICDP-sponsored UrbEnLab workshop brought together 75 scientists from 17 countries to plan a monitoring borehole between the cold-water injector and hot-water producer, highlighting a crucial knowledge gap: how does the subsurface respond to long-term cooled-water injection?
We therefore propose drilling a multi-use monitoring and exploration borehole of at least 3000 m depth to test the hypothesis that new monitoring and modelling techniques can measure, visualise, and forecast the long-term thermal, mechanical, and (bio)geochemical behaviour of an operating geothermal system when key state variables and rock and fluid properties are observed and constrained to the best possibilities. The project will combine monitoring, geological analysis, system optimisation, risk assessment, and societal engagement to advance geothermal science. Its primary goal is to image the cold front in an operational geothermal doublet, while there is the possibility to explore deeper targets.
With the borehole, we will perform time-lapse 3D geophysical monitoring focusing on surface-to-borehole electromagnetic and fibre-optic sensing. Geological and biogeochemical studies will further characterise the heterogeneity of Delft Sandstone and deeper formations up to 3000 m. Continuous seismic monitoring via fibre-optic sensing, a local network and a portable array, and in situ and laboratory microbial analyses will be performed to manage induced seismicity and biological risks, respectively. Integrated societal impact research will assess the perception of risk, uncertainty, and decision-making processes to ensure responsible deployment of urban geothermal infrastructure.
Feasibility tests show that using multiple surface transmitters in a surface‑to‑borehole electromagnetic setup provides sensitivity to 3D temperature variations within the reservoir. This is not the case for conventional surface-based measurements. New long‑term borehole EM sensors, fibre‑optic seismic monitoring approaches, and passive‑noise surface arrays are under development and evaluation. Incorporating geophysical constraints can improve forecasts of production temperature and cold‑plume migration, reducing uncertainty in geothermal reservoir modelling.
The multi-use borehole will supply high-resolution 3D monitoring data to image the geothermal cold front through time-lapse inversions and enhance long-term reservoir predictions of fluid flow, pressure, and temperature distribution. Combining petrophysical logs with geological insights will improve resolution and reduce uncertainty in reservoir forecasts. Consequently, through the proposed monitoring and exploration borehole in the Delft campus geothermal reservoir, it will be possible to assess a geothermal system’s evolution in a heterogeneous setting representative of many low-enthalpy systems worldwide. By integrating in-depth simulation and monitoring of dynamic reservoir processes with detailed characterisation, it will enhance understanding of subsurface behaviour for current and future energy operations and create a unique, open, field-scale research infrastructure to address emerging scientific questions.
How to cite: Rulff, P., Abels, H., Fulton, P., and Bretaudeau, F. and the extended SEE-MORE team: Towards SEE-MORE - A multi-use borehole for optimisation of Subsurface Energy Exploration and MOnitoring of low-enthalpy geothermal REsources , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-10916, https://doi.org/10.5194/egusphere-egu26-10916, 2026.
The C-Drill Core Repository, currently under development at the CNR - Territorial Research Area of Rome 1, is designed to address this gap by establishing a national reference facility for the conservation, management and scientific reuse of continental drilling cores. The repository will accommodate approximately 50–70 km of cores stored in controlled environments (+4 °C, room temperature, −20/−80 °C), supported by high-density mobile racking, automated climate control and continuous environmental monitoring. The facility will also host dedicated laboratories for core splitting and handling, high-resolution and multispectral imaging, XRF scanning, physical property logging (MSCL), wet and dry sample preparation, and microscopy. These capabilities will enable non-destructive characterisation and advanced analytical workflows directly linked to the archived materials.
A fully integrated digital workflow will be implemented, including systematic core digitisation, LIMS-based traceability, a standardised sample request system and interoperability with international data repositories in compliance with FAIR principles (e.g. PANGAEA, EarthChem, mDIS).
Conceived as a modular and scalable infrastructure, C-Drill will ensure high standards of climatic stability, data integrity, safety and user accessibility. The repository will provide services to national research institutes, universities and public agencies; support training activities for early-career scientists and technical staff; and generate interoperable datasets aligned with ICDP/IODP³, EPOS and other international frameworks.
By overcoming the current fragmentation of continental core archives in Italy, C-Drill will harmonise procedures for core acquisition, documentation and access with the best practices of leading European and international repositories. At the same time, it will enhance research efficiency, foster multidisciplinary collaboration and strengthen Italy’s capacity to participate in major international scientific drilling initiatives.
This contribution presents the design rationale, functional requirements, technological solutions and planned user services of the C-Drill Core Repository. The EGU platform will be used to engage potential partners, gather community feedback and refine the development roadmap towards full integration into the international scientific drilling network.
How to cite: Iadanza, A., Tentori, D., Mazzini, I., and Giaccio, B.: A national hub for continental scientific drilling: the C-DRILL core repository at CNR (Italy), EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-12539, https://doi.org/10.5194/egusphere-egu26-12539, 2026.
