Studying life in the deep, rocky subseafloor involves many layers of technological and methodological challenges, and each drilling project or expedition must make a series of choices to address these challenges. We report on the workflow for sampling hard rock cores for microbiological and biogeochemical research that was developed and optimized during International Ocean Discovery Program (IODP) Expedition 399. All steps of the workflow, including selection of the sample and its shipboard homogenization and subsampling for specific analyses, were designed to maximize the potential for interdisciplinary collaborations and syntheses of results. Furthermore, multiple strategies to minimize and detect potential microbial and organic chemical contamination of the core samples were employed, including the shipboard detection of a fluorescent chemical tracer pumped into the drill fluid. Contamination tracer levels were detectable on the exterior surfaces of the core but absent in the homogenized interiors of most core samples. Based on the experiences and preliminary results of this expedition, recommendations for processing samples on future expeditions are presented.
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 similar to 12 m, sediments from the drill core represent a single lithostratigraphic unit, assigned to the Solim & otilde;es 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.
X-ray computed tomography (XCT) scans are one of the first measurements performed after the recovery of cores during expeditions using the drilling vessel (D/V) Chikyu. Despite their completeness and availability, XCT scan data have not been effectively utilized for routine visual core description and shipboard sampling. We designed a Python-based visualization workflow that is compatible with the systems on D/V Chikyu and implemented it in the onboard core workflow.
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 similar to 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.
Low-enthalpy geothermal heat production is becoming increasingly common, which leads to the potentially competitive use of the available subsurface space, especially in densely populated urban areas. A specific challenge presented by the high density of different geothermal systems is understanding the details of convective and conductive heat flow processes and detailed monitoring of properties and processes in the subsurface. On the TU Delft campus, we aim to drill a borehole of around 4.5 km depth to be used for the exploration, observation, and monitoring of subsurface processes that will be part of a larger research infrastructure under development. This so-called urban energy laboratory includes - in addition to the deep multi-use borehole - a well-instrumented geothermal doublet drilled in 2023, reaching to a depth of 2.2 km; a local seismic monitoring system (installed in 2022); an ultra-sensitive portable seismic monitoring array; and a high-temperature aquifer heat storage system (HT-ATES), for which a pilot well was drilled in 2024. With this urban energy laboratory, we want to tackle problems and better understand processes related to multiple and/or competing subsurface uses in urban environments. The deep exploration and monitoring borehole is designed specifically to monitor fluid and/or flux movement in 3D with unprecedented precision, aiming to understand the propagation of the geothermal cold front and reservoir pressures. During the 3 d International Continental Scientific Drilling Program (ICDP)-sponsored UrbEnLab workshop, 75 scientists from 17 countries met in Delft, the Netherlands, in June 2024 to prioritize the scientific ambitions of the deep exploration and monitoring borehole and to discuss potential techniques that could be applied to tackle them. Assessing the life cycle of a geothermal system situated in a complex heterogeneous sedimentary system was defined as the broad aim, with revealing the detailed flow field established being a key priority.
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.
X-ray computed tomography (XCT) scanning is routinely conducted on board the drilling vessel Chikyu for scientific expeditions. A rapid visualization method, developed during International Ocean Discovery Program (IODP) Expedition 405, unwraps XCT images to enable the early characterization of sediment heterogeneities and identification of geological structures at the visual core description stage.
The Bushveld Complex is a renowned crystalline igneous intrusion, with various hypotheses regarding its origin. However, the role of post-magmatic hydrothermal fluids in its evolution remains underexplored. The present hydrogeological study, based on data derived from a deep exploration well drilled into the eastern limb of the Bushveld Complex as part of the Bushveld Complex Drilling Project (BVDP) funded by the International Continental Scientific Drilling Program (ICDP) and which intersects with a lamprophyre dyke at depth, highlights geochemical and structural indicators of deep-seated hydrothermal fluid migration within the crystalline formation. A distinct hydrogeochemical transition is observed at 450 m below ground level, coinciding with a severely fractured anorthosite layer, with evidence of mineral crystallisation from post-magmatic hydrothermal fluid migration. The zone is characterised by a significant increase in total dissolved solids (TDSs), sodium, chloride, sulfate, calcium, potassium, zinc, fluoride and boron concentrations, as well as elevated concentrations of redox-sensitive trace metals such as iron and manganese, in addition to stable isotope deviations. These signatures suggest hydrothermal fluid-rock interactions facilitated by structural conduits for fluid migration, such as dykes and fractured zones. The hydrogeological data and geological features suggest deep-seated, saline and potentially volatile-rich fluid migration, which has implications for post-magmatic hydrothermal mineralisation and groundwater evolution. The potential association of these fluids with volatiles poses exploration risks and highlights the need for integrated gas monitoring. Real-time drilling fluid analysis and isotopic characterisation are recommended to better elucidate fluid sources and migration pathways. These findings contribute to an updated understanding of post-magmatic processes using geochemical indicators to inform future exploration and groundwater management strategies in these fractured crystalline formations.
Portable and core-scanning X-ray fluorescence (XRF) instruments have become increasingly utilized in making rapid, non-destructive chemical characterizations with high spatial resolution on a range of materials. Since basaltic cores are often highly fractured and uneven, portable XRF (pXRF) is preferred to conduct discrete chemical analyses. However, in this case, the user must select the location for each analysis, which can lead to biased datasets. Alternatively, XRF core-scanning (XRF-cs) instruments take a series of measurements along a section of core, increasing the number of analyses and, therefore, eliminating some of the bias introduced by discrete analyses conducted with a pXRF. The XRF-cs does, however, still require a flat sampling surface along the core that does not include void spaces, making rigid, vesicular, and often cracked basalts suboptimal targets. We collected 797 XRF-cs measurements on three basaltic cores collected during the International Ocean Discovery Program Expedition 396 to evaluate how effectively an XRF core scanner can build large, chemically representative datasets. We developed a method for filtering XRF-cs measurements and calibrated the data using discrete calibrated pXRF analyses and compared the XRF-cs data to pXRF and conventional bulk-rock data using various immobile (e.g., Al, Ti, Zr, Ni, Mn, Zn) and mobile (e.g., K, Ca, Sr) elements. The comparison between datasets shows that (1) the XRF-cs data reproduce trends observed by pXRF and conventional bulk-rock data at both the regional scale and the core scale, and (2) in some cases, the higher spatial resolution of the XRF-cs data reveals geochemical variations that are otherwise obscured using discrete analyses. The workflow outlined by this study can be used to select samples for future studies by efficiently providing reliable geochemical data for characterizing new and legacy hard-rock cores.
The Eifel region of Germany hosts hundreds of distributed volcanoes of Quaternary age in an intracontinental setting. This includes many maar volcanoes, for which the Eifel is the type locality. Laacher See volcano in the eastern part of the region stands out as a sizable (erupted volume of 6.3 km(3) dense rock equivalent or a volcanic explosivity index (VEI) of 6) and dormant but actively deforming and degassing system. Plutonic ejecta clasts in pyroclastic deposits of the Laacher See volcano provide evidence that it is underlain by one of the youngest silicate-carbonatite subvolcanic intrusive complexes worldwide. It has long been appreciated that the Laacher See region has potential to significantly enhance our knowledge on distributed volcanic fields and their specific hazards resulting from high CO2 fluxes from the mantle to the surface, causing active deformation, as well as diffuse and sometimes punctuated explosive degassing. This is largely due to the Eifel boasting an extensive record of past research, easy access, and excellent infrastructure that uniquely permits implementation of cutting-edge scientific methods. Recently, three workshops were held to sharpen scientific questions of global scope and relevance to study this type of distributed volcanism. Workshop participants discussed opportunities and challenges associated with drilling in the Laacher See region, identified promising sites, and explored the potential of novel drilling techniques. The clear conclusion of these workshops is that Laacher See would be an ideal test bed to evaluate the physical and chemical properties of a shallow (similar to 4-6 km depth at its top, thus making it accessible to drilling) silicate-carbonatite intrusive complex formed by volatile-rich melts and associated with active degassing. Only drilling can provide answers to key problems related to the geodynamics, geohazards, and resource potential of such magma systems. Questions include how and at what rates translithospheric transport of magma and fluids occurs in continental intraplate settings. It is also puzzling why shallow fluids above a residual magma system after an eruption that occurred only 13 000 years ago are seemingly cold, although the system still appears to be highly dynamic based on ongoing CO2 degassing, seismic activity, and exceptionally high uplift rates on spatial scales of hundreds of kilometres. Critically, drilling enables linking deep and shallow observables related to melt and fluid migration and provides access to samples of CO2-rich fluids and their host rocks at depth. Such samples are tangible evidence required to properly balance CO2 fluxes from degassing magma with CO2 sequestration in carbonatites or fluid-precipitated carbonates. Core samples from a maar structure proximally to the Laacher See volcano can establish an unprecedented geological record of precursor events prior to its cataclysmic eruption. Importantly, drilling also permits improved geophysical monitoring from instrumented wells that can reveal high-resolution details on maar diatreme architecture and deflation-related faulting resulting from the evacuation of the Laacher See magma reservoir. Lastly, silicate-carbonatite intrusions are globally recognised as major hosts for critical metal deposits, which, at Laacher See, could be topics of investigation in the making. Ultimately, this project can provide fundamental insights into processes of fluid-mediated element transport and sequestration not achievable in inactive carbonatites. Overall, these goals are best achieved in two phases that encompass drilling (1) four holes (300-2000 m) to enable detailed studies of the pre-eruptive evolution of the Laacher See volcano, its subvolcanic structures, and ongoing fluid or magma transport and (2) a subsequent deep hole (3000-4000 m) to penetrate and core a syenitic-carbonatitic intrusive carapace and its hydrothermal aureole.
The Rates of Interglacial Sea-level Change and Responses (RISeR) project, funded by the European Research Council, seeks to interrogate Earth system responses to Quaternary climate variability using sedimentary archives preserved in the southern North Sea. Fundamental to the project is the retrieval of five new marine cores, sited to intersect sediments associated with Middle and Late Pleistocene formations identified through earlier regional stratigraphic research and detailed seismic information acquired at the Hollandse Kust Zuid (HKZ) offshore wind farm in the Dutch North Sea (Southern Bight). Drilling of the five cores was carried out in July 2020 using Fugro's geotechnical drilling vessel, MV Normand Flower. The new cores total ca. 62 m of retrieved sediment, reaching a maximum drill depth of 54.3 m below the lowest astronomical tide. Here, we present the lithostratigraphy of the RISeR cores and combine this new sedimentary dataset with high-resolution seismic reflection data. This reveals the preserved Middle and Late Pleistocene stratigraphy of the HKZ wind farm to be predominantly terrestrial and partly coastal and shallow marine.
The EDYTEM Manual Core Opening Bench (MCOB) is a manually operated tool designed for opening soft sediment cores. This reproducible device was inspired by several existing, but as yet unpublished, models and was developed to ensure clean and precise cuts without contamination from plastic debris. The system comprises six technical components (frame, guiding system, sled, drive mechanism, core holding system, and cutting tools) and can accommodate cores of various diameters. Its hand-operated design enhances both safety and portability. All technical drawings, parts lists, and assembly guides are freely available via a GitHub repository, enabling the scientific community to reproduce and enhance the device.
The Atacama Desert is one of the driest deserts on Earth, with a predominantly hyperarid climate since at least the Miocene. Geological evidence, however, indicates that this overall hyperaridity was repeatedly interrupted by wetter periods. Deep-time precipitation reconstructions of the Atacama Desert are limited by scarce and discontinuous sediment sequences, most of which received moisture from wetter regions outside the Atacama Desert. Longer archives of the precipitation history in the desert interior during the Neogene are unfortunately extremely rare. The sediment records of two tectonically blocked endorheic basins (also known as clay pans) in the Coastal Cordillera of northern Chile may fill the gaps in the paleo-precipitation record of the Atacama Desert. Comprehensive investigations of both clay pans applied intensive geological and geophysical site surveys and deep-drilling operations with subsequent downhole logging. Short pilot cores of up to 6.2 m in length already showed highly variable sediment successions reflecting strong hydroclimatic fluctuations on glacial–interglacial timescales. Electromagnetic and seismic surveys yielded a three-layer structure in both basins consisting of the resistive basement overlain by a low-resistivity basal and a high-resistivity upper sediment unit with total sediment thicknesses of more than ∼ 100 and ∼ 160 m in the Playa Adamito Grande (PAG) and Paranal clay pans, respectively. Assuming similar sedimentation rates to those of the pilot cores, this would imply that the sediment records of both clay pans span several million years. Lithological data and downhole-logging results of the deep-drilling operations reveal strong heterogeneities in the sediment composition that presumably can be traced back to major climatic and/or tectonic shifts in the catchments of the clay pans. Whereas the fine-grained sediments at the base of the PAG sequence suggest longer-lasting lacustrine sedimentation with enhanced evaporative episodes, the lower sediment unit in the core from the Paranal clay pan consists of fluvial conglomerates and sandstones. Both lacustrine and fluvial sediments indicate less arid conditions in the central Atacama Desert than today. Separated by distinct lithological boundaries, the upper sediments in both clay pans show several similar sediment facies typical of alluvial-fan deposition, e.g., proximal mudflows and debris flows, sheetflood, and distal alluvial sediment flows, but also pedogenic calcium sulfates. The shift to a predominant alluvial-fan deposition, which is common after torrential rainfall in the Atacama Desert today, implies a general modification of the environmental conditions of the study areas. These initial results already highlight the potential of the sediment records from the PAG and Paranal clay pans to provide unprecedented information on the Neogene precipitation history in the hyperarid core of the Atacama Desert.
During the last 5 million years (Pliocene-Holocene), the Earth climate system has undergone a series of marked changes, including (i) the shift from the Pliocene warm state to the Pleistocene cold state with the intensification of Northern Hemisphere glaciation; (ii) the evolution of the frequency, magnitude, and shape of glacial-interglacial cycles at the Early Middle Pleistocene Transition (similar to 1.25-0.65 Ma); and (iii) the appearance of millennial-scale climate variability. While much of this paleoclimate narrative has been reconstructed from marine records, relatively little is known about the impact of these major changes on terrestrial environments and biodiversity, resulting in a significant gap in the knowledge of a fundamental component of the Earth system. Long, continuous, highly resolved, and chronologically well-constrained terrestrial records are needed to fill this gap, but they are extremely rare. To evaluate the potential of the Fucino Basin, central Italy, for a deep-drilling project in the framework of the International Continental Scientific Drilling Program (ICDP), 42 scientists from 14 countries and 32 institutions met in Gioia dei Marsi, central Italy, on 24-27 October 2023 for the ICDP-supported MEME (the longest continuous terrestrial archive in the MEditerranean recording the last 5 Million years of Earth system history) workshop. The existing information and unpublished data presented and reviewed during the workshop confirmed that the Fucino Basin fulfils all the main requisites for improving our understanding of the mode and tempo of the Plio-Quaternary climatic-environmental evolution in a terrestrial setting at different spatial and temporal scales. Specifically, the combination of the seismic line evidence with geochronological and multi-proxy data for multiple sediment cores consolidated the notion that the Fucino Basin infill (i) is constituted by a sedimentary lacustrine succession continuously spanning at least 3.5 Myr; (ii) has a high sensitivity as a paleo-environmental-paleoclimatic proxy; and (iii) contains a rich tephra record that allows us to obtain an independent, high-resolution timescale based on tephrochronology. Considering the typical half-graben, wedge-shaped geometry of the basin, four different potential drilling targets were identified: MEME-1, located in the middle of the basin, should reach the base of the Quaternary infill at similar to 500 m depth; MEME-2, located west of MEME-1, has sedimentation rates that are lower, with the base of the Pliocene-Quaternary at similar to 600 m depth; MEME-3b has the same target as MEME-2 but is located further west, where the base of the Pliocene-Quaternary should be reached at similar to 300 m; and MEME-3a (similar to 200-300 m depth) is located, for tectonic purposes, on the footwall of the basin master fault. Overall, the MEME workshop sets the basis for widening the research team and defining the scientific perspectives and methodological approaches of the project, from geophysical exploration to the development of an independent chronology and to the acquisition of multi-proxy records, which will contribute to the preparation of the full MEME proposal.
Glaciers have shaped the Alpine landscape by carving deep valleys and depositing sediments to form overdeepened basins. Understanding these processes provides information on the evolution of the climate and landscape. One such overdeepened structure is the Tannwald Basin (ICDP site 5068_1) north of Lake Constance, which was formed by the Rhine Glacier in several glacial cycles. In order to study these sediments and their seismic properties down to about 160 m depth, we conducted seismic crosshole experiments between three boreholes, obtaining compressional (P) wave data. The P-wave data are generated by a sparker source and recorded by a 24-station hydrophone string. We present the data acquisition and review our approach for future optimization, suggesting a finer time sampling interval and a separate registration of borehole and surface receivers. Travel-time tomography of the P-wave first-arrival picks under geostatistical constraints yields initial subsurface models. The tomograms correlate well with cased-hole sonic logs and the lithology derived from the core of one of the boreholes. These results will be further investigated in future research, which will include full-waveform inversion (FWI) to obtain high-resolution subsurface models.
Drilling target locations of the International Continental Scientific Drilling Program (ICDP) project Drilling the Ivrea–Verbano zonE (DIVE) have been initially proposed based on geological knowledge of surface outcrops and the structural context of the Ivrea–Verbano zone (IVZ) and of the Insubric Line. For the determination of the exact locations of drilling sites as well as for drilling geometry planning, we have carried out a series of active seismic experiments to image the subsurface at high resolution. The two drilling sites of project DIVE in Ossola Valley, one near Ornavasso and the other in Megolo di Mezzo, in the central part of the Ivrea–Verbano zone have been surveyed with site-specific velocity models and a seismic data processing chain. The findings have been interpreted in relation with the outcropping structures. These suggest a reasonable continuity from the surface. They also guide the planned borehole orientations: near-vertical at DT-1B (Ornavasso) into the tightly folded Massone Antiform and at 15–20° from the vertical in Megolo across a flank of the broad Proman Anticline. The seismic surveys indicate that the sedimentary overburden is up to 50 m deep at the specific drill sites and can be minimized by relocating the proposed locations. The seismic surveys also indicate that the center of the Ossola Valley contains about 550 m of sedimentary infill, defining the interface of bedrock and Quaternary glacial sediments at about 300 m below sea level.
Rifts and rifted margins form when continents break apart and shape the continent-to-ocean transition on much of our planet. The sedimentary basins that result from continental rifting host unique sedimentary archives of palaeo-environmental and palaeo-climatic change required to understand complex natural processes. Rifts and rifted margins are key sites for natural resources (e.g. geothermal and hydrogen potential, critical metal resources, and CO2 storage) and have an important societal relevance in the mitigation of geohazards such as earthquakes and volcanic activity. However, knowledge on the tectonic structure, sedimentary architecture, rapid palaeo-environmental change, fluid flow and hydrothermal circulation, deep subsurface biosphere, and their impacts on biogeochemical fluxes in rift basins remains poorly understood. Considering their large scientific potential and societal relevance, understanding the formation and architecture of rifts and rifted margins is now critical. The Afar rift is a world-class natural field lab where continental breakup can be directly observed. The northern part of Afar, the Danakil Depression, especially represents a unique snapshot in space and time when the continent ruptures and new seafloor and adjacent rifted margins form. However, deep subsurface records are missing in the basin. The ADD-ON project aims at deep drilling in the Danakil Depression to provide a unique sedimentary record in an active rift basin paced by global environmental fluctuations and their interplay with volcanic and tectonic events. To explore drilling targets and address scientific drilling objectives, an International Continental Scientific Drilling Program (ICDP) workshop was organized in Addis Ababa, Ethiopia, in August 2023. In total, 64 participants from 10 countries and all career stages respecting diversity and inclusion joined the workshop. They represented a wide range of scientific disciplines including government agencies, industry, local universities, and communities to discuss the overall ADD-ON science plan during several workshop sessions. One target drilling site has been flagged, covering the unique Pleistocene full syn-rift sedimentary record in the Danakil Depression. This unique sedimentary archive will allow us to (1) unravel complex palaeo-environmental change in a rift basin, (2) understand incipient and intermittent dynamics through punctuated volcano-tectonic events in a rift transitioning from continental rifting towards seafloor spreading and adjacent rifted margin development, (3) test the origin and limits of life in the deep biosphere under poly-extreme conditions, (4) better understand fluid flow and fluid–sediment interaction in an active hydrothermal system, and (5) use the drilling site to develop a downhole Earth observatory to improve hazard-related monitoring capacity (earthquakes, gas/fluid flux, ground motion).
The Alpine region was shaped by repeated glaciations during the Quaternary, which led to the formation of overdeepened valleys and basins. These features today, hidden below the present-day land surface, host multiple stacked and nested glacial sequences and offer valuable insight into the environmental history and geomorphological evolution of the region. The project Drilling Overdeepened Alpine Valleys (DOVE) of the International Continental Scientific Drilling Program (ICDP) is dedicated to investigating such overdeepened structures around the Alps. Within DOVE, we here focus on the Tannwald Basin in southern Germany. Situated distally within the area formerly occupied by the Rhine Glacier piedmont lobe; it was shaped by multiple glaciations, yet it is located outside the Last Glacial Maximum (LGM) ice extent. Previous seismic imaging and the presence of interglacial pollen sequences indicate a multi-phase infill history. The complex sedimentary architecture observed in a newly drilled core allows for comparison with seismic data and lithological evidence from other sites. On the basis of a lithofacies model that introduces 17 lithotypes, we propose that the basin fill is composed of three lithostratigraphic units that reflect the glacial history of the basin. After the erosion of the Tannwald Basin, a cold-climate, stacked basin-infill sequence recorded sedimentation of two glacial advances, before it was covered by LGM outwash. The sedimentary record includes an extensive basal glacial shear zone with deformed bedrock and several overlying diamict horizons. Further upcore, deformation structures underscore the role of gravitational processes as well as profound glaciotectonics, deforming the sediment deep within the subsurface. While the sedimentary record indicates a rather rapid infill of the depression, further age constraints and detailed investigations of ice-contact sediments will clarify open questions regarding the temporal classification of the deposits.
Fault slip is a complex natural phenomenon involving multiple spatiotemporal scales from seconds to days to weeks. To understand the physical and chemical processes responsible for the full fault slip spectrum, a multidisciplinary approach is highly recommended. The Near Fault Observatories (NFOs) aim at providing high-precision and spatiotemporally dense multidisciplinary near-fault data, enabling the generation of new original observations and innovative scientific products. The Alto Tiberina Near Fault Observatory is a permanent monitoring infrastructure established around the Alto Tiberina fault (ATF), a 60 km long low-angle normal fault (mean dip 20°), located along a sector of the Northern Apennines (central Italy) undergoing an extension at a rate of about 3 mm yr−1. The presence of repeating earthquakes on the ATF and a steep gradient in crustal velocities measured across the ATF by GNSS stations suggest large and deep (5–12 km) portions of the ATF undergoing aseismic creep. Both laboratory and theoretical studies indicate that any given patch of a fault can creep, nucleate slow earthquakes, and host large earthquakes, as also documented in nature for certain ruptures (e.g., Iquique in 2014, Tōhoku in 2011, and Parkfield in 2004). Nonetheless, how a fault patch switches from one mode of slip to another, as well as the interaction between creep, slow slip, and regular earthquakes, is still poorly documented by near-field observation. With the strainmeter array along the Alto Tiberina fault system (STAR) project, we build a series of six geophysical observatory sites consisting of 80–160 m deep vertical boreholes instrumented with strainmeters and seismometers as well as meteorological and GNSS antennas and additional seismometers at the surface. By covering the portions of the ATF that exhibits repeated earthquakes at shallow depth (above 4 km) with these new observatory sites, we aim to collect unique open-access data to answer fundamental questions about the relationship between creep, slow slip, dynamic earthquake rupture, and tectonic faulting.
The BASE (Barberton Archean Surface Environments) scientific drilling project aimed at recovering an unweathered continuous core from the Paleoarchean Moodies Group (ca. 3.2 Ga), central Barberton Greenstone Belt (BGB), South Africa. These strata comprise some of the oldest well-preserved sedimentary strata on Earth, deposited within only a few million years in alluvial, fluvial, coastal-deltaic, tidal, and prodeltaic settings. They represent a very-high-resolution record of Paleoarchean surface conditions and processes. Moodies Group strata consist of polymict conglomerates, widespread quartzose, lithic and arkosic sandstones, siltstones, shales, and rare banded-iron formations (BIFs) and jaspilites, interbedded with tuffs and several thin lavas. This report describes objectives, drilling, and data sets; it supplements the operational report. Eight inclined boreholes between 280 and 495 m length, drilled from November 2021 through July 2022, obtained a total of 2903 m of curated core of variable quality through steeply to subvertically dipping, in part overturned stratigraphic sections. All drilling objectives were reached. Boreholes encountered a variety of conglomerates, diverse and abundant, mostly tuffaceous sandstones, rhythmically laminated shale-siltstone and banded-iron formations, and several horizons of early-diagenetic silicified sulfate concretions. Oxidative weathering reached far deeper than expected. Fracturing was more intense, and BIFs and jaspilites were thicker than anticipated. Two ca. 1 km long mine adits and a water tunnel, traversing four thick stratigraphic sections within the upper Moodies Group in the central BGB, were also sampled. All boreholes were logged by downhole wireline geophysical instruments. The core was processed (oriented, slabbed, photographed, described, and archived) in a large, publicly accessible hall in downtown Barberton. A geological exhibition provided background explanations for visitors and related the drilling objectives to the recently established Barberton Makhonjwa Mountains World Heritage Site. A substantial education, outreach, and publicity program addressed the information needs of the local population and of local and regional stakeholders.
