Anders Noren

The southern Levant extends between the hyperarid Sahara–Arabia Desert belt in the south and the temperate Mediterranean climate zone in the north, making the regional hydroclimate extremely sensitive to even small perturbations of global climate. The region further served as a major pathway for the “out-of-Africa” dispersal of fauna, flora, and hominins throughout the Quaternary, as well as for human cultural development from the Paleolithic to the Neolithic. Spanning the length of the Levant is the Dead Sea Transform (DST) that transfers the opening at the Red Sea in the south to the collision at the Taurus Mountains in the north. Pull-apart basins along the DST host the hypersaline Dead Sea and freshwater Lake Kinneret, whose sedimentary records document the regional hydroclimate and seismic history. Lake Kinneret (a.k.a. the Sea of Galilee) is the largest freshwater lake in the Levant, whose precursors have deposited a thick sequence of lacustrine sediments since the late Miocene. Seismic profiles across the tectonically subsiding basin in the middle of the modern lake, as well as existing short sediment cores, indicate that the sedimentary sequences are generally bounded by two N–S-striking longitudinal faults and generally maintain stratigraphic order. The sedimentary column is dominated by primary authigenic calcite, whose chemical and isotopic composition documents regional hydrology and lacustrine conditions from at least the Pliocene. Accordingly, the sedimentary record of Lake Kinneret holds the potential to serve as one of the longest and most highly resolved lacustrine records since the Pliocene, yielding sub-centennial records of hydroclimate, paleoseismicity, geomagnetism, and paleobotanics in a region of fundamental importance for the global understanding of climate change, tectonics, and human evolution. The Lake KINneret Drilling (KIND) project aims to establish an exceptionally long Pliocene–Quaternary chronostratigraphic reference record that will contribute to a meridional synthesis of continental and marine core records along the East African Rift–Dead Sea Transform (EARDST) corridor. Owing to its location, the KIND record will yield transformative contributions to climate modeling and to our understanding of climate change in the eastern Mediterranean, a recognized global warming “hotspot”. Moreover, it will document seismic activity along the DST over long timescales, providing a basis for policymakers to prepare for this potential major hazard to infrastructure and human life. Taken together, the KIND project will provide unique and much-needed records from a tectonically active region that is projected to become increasingly arid over the coming century and that is already burdened by severe geopolitical strife. These records are critical for identifying and quantifying regional climate change patterns, assessing seismic risks, and evaluating the ecological impacts of these processes.

The modern Amazon Basin is covered by a wet, tropical rainforest and drained by the Amazon River system flowing from the Andes eastward to the Atlantic Ocean. To better understand Amazonian stratigraphic and vegetation history during the Cenozoic, an 870-m drill core was collected from the Acre Basin in western Amazonia by the International Continental Scientific Drilling Program’s Trans-Amazon Drilling Project (TADP) in 2023. We analyze the hydrocarbon components of solvent extractible lipids along with coaly fragments to characterize plant producers and the paleoenvironment. Coaly fragments at depths below 767m reveal no heating above 71 °C, sufficient to promote microbial degradation but insufficient for thermal cracking, consistent with a plant wax n-alkane carbon preference index (CPI) of mostly >4. n-Alkanoic acid δ13C values average –32.2±1.5‰, broadly consistent with a C3 rainforest, with progressive enrichment with depth hypothesized to result from heterotrophic enrichment. n-Alkanoic acid-reconstructed precipitation δD averages –61±14‰, broadly consistent with values for modern precipitation associated with moisture recycling over a forested landscape, although heterogeneity may indicate pulsed deposition with differences in provenance. PAHs are variably abundant and include pyrogenic PAHs and retene, the latter likely from bryophytes given gymnosperm scarcity. Overall, the biomarker record supports sustained rainforest conditions and similar-to-modern precipitation patterns, with complexity associated with depositional environment and diagenetic changes. This biomarker evidence will be tested by additional proxy evidence (e.g., carbonates, pollen) in forthcoming work on the continental drill cores.

The Trans-Amazon Drilling Project (TADP) is reconstructing the late Cenozoic history of Amazonian geology, climate, rivers, and forests. Drilling in the Acre Basin of western Brazil in 2023 recovered an 860 m drill core characterized by sediments that were deposited in a large paleo-river system. The overall sequence includes sandstones, siltstones, and mudstones that underwent varied degrees of weathering and pedogenesis. Here, we describe the ongoing geochronologic, geochemical, mineralogical, geophysical, and biotic analyses of the sedimentary record and present some preliminary inferences of the environmental history based on these initial results. Except for the uppermost ∼ 12 m, sediments from the drill core represent a single lithostratigraphic unit, assigned to the Solimões Formation, which is dominated by feldspar-rich sands of Andean origin. The pollen assemblage is quite different from Early to Middle Miocene floras that have been analyzed from a few sites elsewhere in the western Amazon. The novel pollen assemblage and new geochronological results suggest that the sequence may span the latest Miocene and all of the Pliocene Epoch, an interval that currently is not well represented in existing regional records and that is crucial for understanding the evolution of Amazonian biodiversity, as well as landscape transformations driven by Andean uplift and global climate change.

The Nam Co Drilling Project (NamCore) is a multinational and interdisciplinary research initiative designed to understand long-term climatic variability and associated environmental change on the Tibetan Plateau. The project primarily targets the timing and magnitude of Indian/East Asian monsoon variability and its interplay with the Westerlies. Thereby, the glacial–interglacial history and dynamics at high altitude; the impact of geological and environmental changes on (micro-)biological processes; the evolution and resilience of high-altitude ecosystems, including the deep biosphere; and geomagnetic variations during the Quaternary are of special interest. For in-depth investigations regarding the outlined research purposes, the (mostly) calcareous sediments of Nam Co, one of the largest and deepest lakes on the Tibetan Plateau, were targeted within the framework of the International Continental Scientific Drilling Program (ICDP) and cored in May–July 2024 (ICDP Expedition 5073). Altogether, 1415.45 m was drilled and 1175.99 m cored, with 950.77 m of sediment recovered (core recovery of 80.8 %) from seven holes at one site (5073_1) situated at a water depth of ∼ 93 m, reaching a maximum depth of 510.2 m below the lake floor. Initial results from core descriptions and preliminary core catcher analyses suggest that the sediments of Nam Co reflect the evolution of a dynamic high-altitude lake system over multiple glacial–interglacial cycles. Four major lithologies are observed in the drill cores (calcareous mud, non-calcareous mud, calcareous mud with ferric staining and sand) and grouped into five major lithological units based on their physicochemical characteristics obtained from core catcher material. Micropaleontological results from core catcher material reveal a general absence of diatoms, due to unsuitable growing and/or preservation conditions, while ostracods abundances, preservation, and species composition vary, which might be linked to environmental changes and/or changing preservation conditions. Shifts in n-alkane chain length might be attributable to lake-level variations and/or glacial–interglacial cycles.

Chew Bahir, a lake that is dry for most of the year, located in a tectonic basin in the southern Ethiopian Rift, was the target of several scientific drilling expeditions between 2009 and 2014. The aim of these expeditions was to explore the basin and its lake sediments as an archive of past changes in the environmental conditions during the evolution of our species, Homo sapiens. In more than 25 publications, the scientific findings derived from the analysis of the sediments were presented and discussed in detail. In the present paper, we provide the background information on the project's origins, planning and implementation – that is, information that has not yet been presented in scientific papers, or only very briefly, but which could be important for those working on similar projects in the future. Herein, we particularly focus on the advantages and disadvantages of obtaining twin cores at a short distance, aiming at a continuous high-quality composite core, a strategy that had to be defended during the planning stage of the project due to the higher costs involved but which is considered to be the best practice for scientific drilling in modern sedimentary basins.

The critical zone (CZ), extending from the vegetation canopy to the base of weathered material or depth of groundwater, hosts coupled hydrologic, geochemical, and biological interactions that regulate soil health, water resources, and ecosystem sustainability. The subsurface CZ can extend tens to hundreds of metres below the surface and is largely inaccessible, except in happenstance exposures from quarries or road cuts through mountain hillsides. Drilling and subsequent borehole sampling, monitoring, and imaging reveal the importance of the deep subsurface for CZ evolution and function. However, drilling can be labour‐intensive, requires expensive, specialised equipment, and can only be done where the equipment can be deployed, limiting the number and placement of boreholes. Despite these challenges, drilling provides invaluable insights into deep CZ processes. To empower the next generation of CZ scientists to employ drilling and downhole techniques, this review synthesises emerging research objectives and methods commonly used during CZ drilling campaigns over the last 30 years. We focus on three CZ research themes: (1) physical and chemical weathering, (2) water storage and partitioning, and (3) solute, microbial, and gas dynamics. For each theme, we evaluate drilling techniques, sampling strategies, downhole logging approaches, long‐term monitoring, and analytical methods that collectively enable diverse hypothesis‐testing. We conclude by providing a vision for the future of drilling within the CZ, with a focus on novel drilling techniques aimed at recovering saprolitic material as well as borehole designs that can monitor and sample the vadose zone. Additionally, we emphasise that near‐surface geophysics and data‐model integration efforts are needed to expand borehole observations to the landscape scales necessary to advance CZ science and inform ecosystem and water resource management.

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.

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.

Cores recovered by the Trans-Amazon Drilling Project (TADP) in the Acre Basin provide an unprecedented opportunity to investigate the stratigraphic record in the Andean foreland in the western Brazilian Amazon. This study integrates subsurface data with sedimentological data of correlative units from outcrops along the Juruá River and roadcuts, providing key information on depositional geometry and architectural elements. The entire sampled interval of the core (870 m), except the uppermost 12 m, is assigned to a single lithostratigraphic unit, identified as the Solimões Formation. The core succession comprises fine- to medium-grained sandstones, siltstones, and mudstones, exhibiting variable degrees of paleopedogenetic alteration. The sand-grade facies are rich in feldspar grains and lithic fragments, displaying a grayish coloration that contrasts with the reddish oxidized hues and locally green-mottled colors observed in more intensely paleoweathered profiles. Four facies associations (FA) are defined: sandy fluvial channel deposits (FA1 and FA2) and finer-grained overbank and floodplain deposits (FA3 and FA4). Facies associations FA1 and FA2 are best represented by deposits exposed along the BR-364 highway in the eastern Acre Basin, where they form channel-dominated sandy successions, with homogeneous successions up to 1.5 m thick. FA3 and FA4 are best represented by deposits exposed along the Juruá River riverbanks in the western Acre Basin, characterized by laterally extensive tabular beds intercalated with thin sandy bodies deposits forming fine-grained heterolithic deposits, generally with well-developed paleoweathering features and cemented by calcite. Subsurface deposits from the core record a phase of long-term aggradation associated with foreland basin subsidence. These facies are interpreted as bar top deposits transitioning into floodplain environments of a large alluvial system, with very limited occurrence of lacustrine sequences. The limited lateral accretion in floodplain or shallow pond environments was subject to repeated subaerial exposure with prolonged floodplain stability under waterlogging and/or seasonal discharge variability. Further refinement of these interpretations, together with ongoing geochronological and geochemical analyses, should help to improve our understanding of Amazonian basin development and its linkage to climate and tectonic change through the Late Miocene and Pliocene.

After the climatic and environmental context of hominin evolution in East Africa centred the spotlight for decades, West Africa gains increasing interest considering a pan-African early human history. However, long and continuous continental climate records from this area illuminating regional hydroclimatic impacts and differences across Africa are missing. This is a major shortcoming as fundamental offsets in W-E hydroclimates are expectable that may have influenced human dispersal. Here we present the million-year-old hydroclimate record from Lake Bosumtwi in tropical West Africa, suggesting that this area has been strongly impacted by hemispheric system interactions (N-S-Atlantic, 100 ka cycles) and local insolation including half-precession. Comparing our findings with records from tropical East Africa governed by an Indian Ocean signal (20 ka, 400 ka cycles), we can confirm strongly contrasting hydroclimatic trends. To understand the meaning of these, we compare hydroclimatic signals from Lake Bosumtwi and Chew Bahir (tropical East Africa) providing us with important relative (moister-dryer) information with climate model output data delivering mean annual precipitation (MAP) estimates. This reveals striking similarities between the considered geoscientific data and climate models raising confidence that the MAP estimates can be reliably used to infer supported biomes. Whilst modelled MAP at Lake Bosumtwi varies between 1050 mm (wet savannah) and 1550 mm (rainforest), Chew Bahir may have been characterised by thorn to dry savannah conditions (550-750 mm/a). In this context, cross-Africa climate modelling suggests that large W-E savannah corridors supporting migration of large mammals and humans spread during periods, when the differences between MAP at both end-members have been low. In contrast, these corridors are interrupted by conditions supporting rainforests, when δMAP is high. These phases coincide with major steps in the evolution of the mega-fauna and hominins providing us with a basis for discussing new perspectives on climate and human co-evolution scenarios.