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Presented here is a transfer‐learning model for classifying basin‐scale stratigraphic geometries from subsurface formation tops. Support vector, decision trees, random forests, AdaBoost and K‐nearest neighbour classification models are evaluated to support this challenge. Each model is trained on labelled synthetic stratigraphic geometry data generated in Python using observable geological principles and concepts. Accuracy is measured using a weighted Jaccard similarity coefficient score, and certainty of each prediction is quantified using margin sampling. The random forest classifier has the highest initial accuracy, and the optimal hyperparameters for the model that yield 88.4% accuracy and 72.8% mean certainty via five‐fold cross‐validation and active learning are documented on a real‐world subsurface dataset. The random forest classifier with optimised hyperparameters is then used to make predictions on the real‐world subsurface formation tops dataset. The dataset consists of formation tops for the Upper Cretaceous and Palaeocene strata of the Eastern Greater Green River Basin in south‐central Wyoming. Results from model predictions include an area of truncation in the Lance Formation across the basin, and an area of onlap and truncation on the nose of the Rock Springs Uplift that previous studies in the region corroborate. It is believed that this model is most useful for guided interpretation, and identifying regions that warrant further inquiry by domain experts.

The island of Surtsey was formed in 1963–1967 on the offshore Icelandic volcanic rift zone. It offers a unique opportunity to study the subsurface biosphere in newly formed oceanic crust and an associated hydrothermal-seawater system, whose maximum temperature is currently above 120°C at about 100m below surface. Here, we present new insights into the diversity, distribution, and abundance of microorganisms in the subsurface of the island, 50years after its creation. Samples, including basaltic tuff drill cores and associated fluids acquired at successive depths as well as surface fumes from fumaroles, were collected during expedition 5059 of the International Continental Scientific Drilling Program specifically designed to collect microbiological samples. Results of this microbial survey are investigated with 16S rRNA gene amplicon sequencing and scanning electron microscopy. To distinguish endemic microbial taxa of subsurface rocks from potential contaminants present in the drilling fluid, we use both methodological and computational strategies. Our 16S rRNA gene analysis results expose diverse and distinct microbial communities in the drill cores and the borehole fluid samples, which harbor thermophiles in high abundance. Whereas some taxonomic lineages detected across these habitats remain uncharacterized (e.g., Acetothermiia, Ammonifexales), our results highlight potential residents of the subsurface that could be identified at lower taxonomic rank such asThermaerobacter, BRH-c8a (Desulfallas-Sporotomaculum),Thioalkalimicrobium,andSulfurospirillum. Microscopy images reveal possible biotic structures attached to the basaltic substrate. Finally, microbial colonization of the newly formed basaltic crust and the metabolic potential are discussed on the basis of the data.

Most studies on sediment-inhabiting microphytobenthos are based on the biomass present on the surface layers of intertidal flats. However, large amounts of microalgal biomass are known to exist below the surface. This study tested the role of subsurface microalgal biomass as a potential source of photosynthetically active cells for the biofilm on the surface. The resilience of buried cells was evaluated by exposing samples from various depths to surface conditions and investigating the recovery of photosynthetic activity. Additionally, vertical migration by subsurface epipelic diatoms was followed at sub-millimeter scales to evaluate its role for transporting cells to the vicinity of the sediment surface. Finally the relative importance of subsurface microalgal biomass was assessed by estimating the proportion of subsurface:surface biomass for different types of sediments from the Ria de Aveiro. Vertical profiles of chlorophyll a, 10 cm-deep, were measured on samples from three intertidal sites, representative of the range of sediment characteristics found in this estuary. The ratio of total biomass to surface biomass (‘subsurface biomass fraction’) based on total biomass (0–10 cm depth interval; Csub, total) and on viable biomass (between the surface and the maximum depth with significant photosynthetic recovery; Csub, viable). The experiments showed that buried cells were able to recover photosynthetic activity within 1.5–3 h of light exposure, with the rate of recovery being dependent on depth and type of sediment. Furthermore, subsurface vertical migration was found to enable motile cells to reach the surface from layers deeper than 1 mm within a low tide period. Overall, the results showed that surface biomass (0–0.5 cm) only accounted for one fifth to one third of the total biomass present between the surface and 10 cm, and that the amount of subsurface viable biomass reached 2–3 times the biomass present at the surface. Applying the estimates of Csub, total and Csub, viable to the whole intertidal area of the Ria de Aveiro, spatially-weighted averages for subsurface biomass fractions were found to reach 3.8 and 2.1 respectively.

Radar‐sounding surveys measuring ice thickness in Greenland have enabled an increasingly “complete” knowledge of basal topography and glaciological processes. Where such observations are spatially limited, bed elevation has been interpolated through mass conservation or kriging. Ordinary kriging fails to resolve anisotropy in bed geometry, however, leaving complex topography misrepresented in elevation models of the ice sheet bed. Here, we demonstrate the potential of new high‐resolution (≤5 m) surface topography data (ArcticDEM) to provide enhanced insight into basal and englacial geometry and processes. Notable surface features, quantified via residual surface elevation, are observed coincident with documented subglacial channels, and new, smaller‐scale tributaries (

In the area of Arcadia Planitia in the Northern hemisphere of Mars, mounds indicating fluid and sediment emissions have been already recognized. Here, we show that through fractal and fracture‐spacing analyses of a large vent population it is possible to infer the mechanical layering of the underlying subsurface. Our work includes the mapping of an entire population of 9,028 vents over an area of 122,000 km2. The analysis of mound distribution at the surface led to the formulation of inferences about the subsurface feeding conduits, and to the identification of three mechanical discontinuities at c. 4–5, c. 14–23, and c. 50–55 km. This evidence matches the mechanical stratigraphy recorded by the InSight NASA mission, and is in agreement with independent previous subsurface global modeling, supporting our conclusions., Plain Language Summary: The Martian northern hemisphere displays mounds interpreted to be the result of sediment and water erupting onto the surface. We analyzed the mounds spatial distribution and found patterns that reflects the extent at depth of the subsurface conduits that fed those mounds (array of fractures, i.e., high permeability pathways) allowing the sediment and water upwelling. These conduits thus connect the surface to the source of the erupted materials at depth. These source levels are located at the base of layers characterized by mechanical properties different from the adjacent ones (e.g., loose sediments vs. crystalline bedrock). Such layers are hence referred as mechanical discontinuities. We identified three discontinuities: at c. 4–5, c. 14–23, and c. 50–55 km. Our outcomes match the mechanical stratigraphy recorded by the InSight NASA mission, and is in agreement with independent previous subsurface global modeling, supporting our conclusions., Key Points: We present a complete mapping of a large vent population in the Arcadia Planitia region of the northern plains of Mars. We reconstructed the subsurface mechanical layering underlying the vent field using spatial distribution analysis. These analyses proved to be efficient and open the possibility of collecting subsurface rheological data from areas beyond InSight reach., H2020 Excellent Science (H2020 Priority Excellent Science) http://dx.doi.org/10.13039/100010662, DLR Management Board Young Research Group Leader Program, Executive Board Member for Space Research and Technology

We present a synthetic hydraulic analysis of the propagation of oscillatory perturbations in a two-dimensional saturated zone bounded above by a capillary fringe. Unsaturated flows are simulated in a physical model using a hysteretic form of Richards' equation parameterized using the van Genuchten water retention curve and the Mualem hydraulic conductivity equation for a sand, loam, and intermediate soil. Soil type affects periodic responses as a function of their hydrodynamic and van Genuchten properties. We first analyze the effect of various hydraulic or signal properties on the oscillatory responses simulated at different locations and depths. We then test the imaging potential of oscillatory responses recorded in the saturated zone to spatially charaterize homogeneous or heterogeneous soils, also considering the effect of period of oscillation. We find that a separation of these responses into amplitude/phase couples permits to dissociate the characterization of different hydraulic properties. Periodic amplitudes decay with distance mainly as a function of hydraulic conductivity and phase lags decrease with frequency due to storage in the capillary fringe. Thus, responses amplitude appears to be especially sensitive to conductivity K , which allows to isolate this property from the others. Phases can then be used to better characterize the vertical flows effect, through the Van Genuchten parameters α and n . Higher periods will tend to accentuate the unsaturated flows effect on the responses and can therefore be adopted for a better characterization of α and n . However, using low-period responses can also be useful, as they provide better estimates of conductivity values in media with low heterogeneities. We consider this work as a useful preliminary analysis for future sandbox or field real cases applications and provide advices for such applications in the discussion.

Despite being considered an extreme environment, several studies have shown that life in the deep subsurface is abundant and diverse. Microorganisms inhabiting these systems live within the rock pores and, therefore, the geochemical and geohydrological characteristics of this matrix may influence the distribution of underground biodiversity. In this study, correlative fluorescence and Raman microscopy (Raman-FISH) was used to analyze the mineralogy associated with the presence of members of the genus Acidovorax, an iron oxidizing microorganisms, in native rock samples of the Iberian Pyrite Belt subsurface. Our results suggest a strong correlation between the presence of Acidovorax genus and pyrite, suggesting that the mineral might greatly influence its subsurface distribution., Spanish MINECO, Project MAT2017-86450-C4-1-R and the Spanish MICINN, Projects PID2019-104812GB-I00 and RTI2018-099794-B-I00 ; With funding from the Spanish government through the "María de Maeztu Unit of Excellence" accreditation (MDM-2017-0737)

The operator of the Groningen gas field is leading an effort to quantify the seismic hazard and risk of the region due to induced earthquakes, including overseeing one of the most comprehensive liquefaction hazard studies performed globally to date. Due to the unique characteristics of the seismic hazard and the geologic deposits in Groningen, efforts first focused on developing relationships for a Groningen-specific liquefaction triggering model. The liquefaction hazard was then assessed using a Monte Carlo method, wherein a range of credible event scenarios were considered in computing liquefaction damage-potential hazard curves. This effort entailed the use of a regional stochastic seismic source model, ground motion prediction equation, site response model, and geologic model that were developed as part of the broader regional seismic hazard assessment. No to minor surficial liquefaction manifestations are predicted for most sites across the study area for a 2475-year return period. The only sites where moderate surficial liquefaction manifestations are predicted are in the town of Zandeweer, with only some of the sites in the town being predicted to experience this severity of liquefaction for this return period. This work is made available under the terms of the Creative Commons Attribution 4.0 International license, https://creativecommons.org/licenses/by/4.0/. Nederlandse Aardolie Maatschappij B.V. (NAM); National Science Foundation (NSF)National Science Foundation (NSF) [CMMI-1435494, CMMI-1724575, CMMI-1825189, CMMI-1937984] This research was partially funded by Nederlandse Aardolie Maatschappij B.V. (NAM) and the National Science Foundation (NSF) Grants CMMI-1435494, CMMI-1724575, CMMI-1825189, and CMMI-1937984. This support is gratefully acknowledged. This study has also significantly benefited from enlightening discussions with colleagues at Shell, Deltares, Arup, Fugro, Beca, and on the Nederlands Normalisatie Instituut (NEN) Liquefaction Task Force, which is coordinated by Dr. Mandy Korff. However, any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the NSF, NAM, or others that are acknowledged.

International audience; Key Points: 28 • Ground compliance measurements by InSight depend on the elastic properties in 29 the near surface of Mars 30 • Observed compliance from convective vortex encounters and other pressure fluc-31 tuations opens the way to the exploration of the near surface 32 • Markov chain Monte Carlo inversion for the Young modulus profile suggests strat-33 ification within and below the regolith 34 Corresponding author: Balthasar Kenda, kenda@ipgp.fr-1-Abstract 35 Measurements of ground compliance at the InSight landing site-describing the surface 36 response to pressure loading-are obtained from seismic and meteorological data. Com-37 pliance observations show an increase with frequency indicating the presence of a stiffer 38 rock layer beneath the exposed regolith. We performed a Markov chain Monte Carlo in-39 version to investigate the vertical profile of the elastic parameters down to 20 m below 40 InSight. Compliance was inverted both freely and assuming prior knowledge of compaction 41 in the regolith, and the limitations and strengths of the methods were assessed on the 42 basis of theoretical considerations and synthetic tests. The inverted Young modulus ex-43 hibits an increase by a factor of 10-100 over the first 10-15 meters, compatible with a struc-44 tural discontinuity between 0.7 and 7 m. The proposed scheme can be used for joint in-45 version of other seismic, geological or mechanical constraints to refine the resulting ver-46 tical section. 47 Plain Language Summary 48 Pressure fluctuations of the Mars' atmosphere induce tiny deformations of the ground 49 that can be measured by the very sensitive seismometer of the InSight mission. The amount 50 of deformation depends on the elastic properties of the sandy regolith (the surface layer 51 exposed and highly fractured by impacts) and of the underlying rocks, and can thus be 52 used to explore beneath the surface. In this work, we review the theory describing the 53 ground motion caused by moving pressure perturbations, and we analyze the effect of 54 various parameters (wind speed, layering in the subsurface). We then develop a method 55 to retrieve a vertical profile of the elastic parameters beneath the lander from the mea-56 surements. After testing the method on ideal cases, we apply it to data from Mars: the 57 results show that the regolith becomes stiffer with depth, and that a layer of harder rock 58 may be present below, with the interface possibly located between 0.7 and 7 depth. De-59 termining the structure of the near surface provides constraints on the geologic history 60 of the landing site and contributes to the explanation of measured seismic signals.

The Kuiseb River is one of the major ephemeral rivers of Western Namibia, setting the northern limit of the Namib Sand Sea and outflowing in the Atlantic Ocean at Walvis Bay. Such ephemeral rivers are of the highest importance for the country since they are related both to recent past climatic conditions and to potential water resources. Using high-resolution radar images from the Japanese ALOS-2 satellite, we mapped for the first time the numerous channels hidden under the surface aeolian sediments: while the non-permanent tributaries of the Kuiseb River appear north of its present-day bed, a wide paleochannel system running westward, assumed by previous studies, could be clearly observed in the interdune valleys in the south. Radar-detected channels were studied during fieldwork in May 2019, which produced both subsurface ground-penetrating radar profiles and high-resolution drone-generated digital elevation models. It allowed us to confirm the existence of the &ldquo, Paleo&ndash, Kuiseb&rdquo, drainage system, a remnant of the Holocene history of the Kuiseb River, moving northward under the progression of the Namib Sand Sea. Our observations also contribute to the explanation of the young age of the linear dunes at the northern edge of the Namib Sand Sea, which are currently active and are pushing the Kuiseb River course toward the north.

Conspicuous chert horizons occur as discontinuous bands and isolated nodules in dolostones in the Eocene Dammam Formation, which is exposed in the southeast of Kuwait. The Formation has never been deeply buried, and so chert formation is likely to have resulted from silicification processes at or near the land surface. Erosional reworking of the chert constrains its formation to a time period between the late Eocene and the Mio-Pliocene. As there is no significant source of silica in the dolostones, the chert was formed from silica imported from other sources. This process, together with the specificity of chert to particular non-bedding horizons, suggests that silicification is related to discrete locations of the groundwater table during landscape incision and resultant groundwater discharge in the region. Detailed petrographical studies demonstrate that “chertification” was initiated by precipitation of nanoglobules of silica (opal-A) from supersaturated groundwater solutions flowing through voids formed concomitantly by dissolution of dolomite. Subsequently, silica was precipitated as more crystalline forms of chalcedony, microquartz, and megaquartz from successively less saturated groundwater. The most likely mechanism for triggering the precipitation of silica is considered to be significant cooling of the groundwater as it neared the landsurface and came into contact with a cold regolith terrain. Precipitation of disordered forms of silica (opal-A) occurred at the cold front: progressively more crystalline phases formed as the host rock was warmed by the inflowing groundwater and its degree of supersaturation diminished. If our interpretation is correct, this “chertification” process could have been initiated during global cooling related to one of the glaciations recorded during Oligocene and Miocene times.

A new analysis modality in Raman microscopy, Micro-Spatially Offset Raman Spectroscopy (micro-SORS) to explore the subsurface of materials in non-destructive and non-invasive way has been developed recently at ICVBC – CNR. Micro-SORS facilitates the investigation of the chemical composition of subsurface, micrometre-scale-thick diffusely scattering layers at depths more than an order of magnitude larger than those accessible with the depth resolving power of conventional confocal Raman microscopy, avoiding need to resort to cross sectional analysis or sampling. In the state of the art paragraph an overall overview of research carried out at CNR-ICVBC in the last five years concerning the development, optimization and application of micro-SORS to Cultural Heritage materials is provided. Additionally, we present new data achieved from the application of micro-SORS to illustrative micro-samples obtained from mediaeval polychrome sculptures of the Parma baptistery and Ferrara cathedral, highlighting further its potential in Cultural Heritage sciences.

Sinuous collapse chains and skylights in Lunar and Martian volcanic regions have often been interpreted as collapsed lava tubes (also known as pyroducts, [1]). This hypothesis has fostered a forty years debate among planetary geologists trying to define if analogue volcano-speleogenetic processes acting on Earth could have created similar subsurface linear voids in extra-terrestrial volcanoes. On Earth lava tubes are well known thanks to speleological exploration and mapping in several shield volcanoes, with examples showing different genetic processes (inflation and overcrusting [1, 2, 3]) and morphometric characters. On the Moon subsurface cavities have been inferred from several skylights in maria smooth plains [4], and corroborated using gravimetry and radar sounder [5, 6] while on Mars several deep skylights have been identified on lava flows with striking similarities with terrestrial cases [7]. Nonetheless, a clear understanding of the potential morphologies and dimensions of martian and lunar lava tubes remains elusive. Although it is still impossible to gather direct information on the interior of martian and lunar lava tube candidates, scientists have the possibility to investigate their surface expression through the analysis of collapses and skylight morphology, morphometry and their arrangement, and compare these findings with terrestrial analogues. In this work we performed a morphological and morphometric comparison with lava tube candidate collapse chains on Mars and the Moon. By comparing literature and speleological data from terrestrial analogues and measuring lunar and martian collapse chains on satellite images and digital terrain models (DTMs), this review sheds light on tube size, depth from surface, eccentricity and several other morphometric parameters among the three different planetary bodies. The dataset here presented indicates that martian and lunar tubes are 1 to 3 orders of magnitude more voluminous than on Earth and suggests that the same processes of inflation and overcrusting were active on Mars, while deep inflation and thermal entrenchment was the predominant mechanism of emplacement on the Moon. Even with these outstanding dimensions (with total volumes exceeding 1 billion of m3), lunar tubes remain well within the roof stability threshold. The analysis shows that aside of collapses triggered by impacts/tectonics, most of the lunar tubes could be intact, making the Moon an extraordinary target for subsurface exploration and potential settlement in the wide protected and stable environments of lava tubes. References [1] Kempe, S., 2019. Volcanic rock caves, Encyclopedia of Caves (Third edition). Academic Press, pp. 1118-1127 [2] Calvari, S. and Pinkerton, H., 1999. Lava tube morphology on Etna and evidence for lava flow emplacement mechanisms. Journal of Volcanology and Geothermal Research, 90(3-4): 263-280. [3] Sauro, F., Pozzobon, R., Santagata, T., Tomasi, I., Tonello, M., Martínez-Frías, J., Smets, L.M.J., Gómez, G.D.S. and Massironi, M., 2019. Volcanic Caves of Lanzarote: A Natural Laboratory for Understanding Volcano-Speleogenetic Processes and Planetary Caves, Lanzarote and Chinijo Islands Geopark: From Earth to Space. Springer, pp. 125-142. [4] Haruyama, J., Morota, T., Kobayashi, S., Sawai, S., Lucey, P.G., Shirao, M. and Nishino, M.N., 2012. Lunar holes and lava tubes as resources for lunar science and exploration, Moon. Springer, pp. 139-163. [5] Chappaz, L., Sood, R., Melosh, H.J., Howell, K.C., Blair, D.M., Milbury, C. and Zuber, M.T., 2017. Evidence of large empty lava tubes on the Moon using GRAIL gravity. Geophysical Research Letters, 44(1): 105-112 [6] Kaku, T., Haruyama, J., Miyake, W., Kumamoto, A., Ishiyama, K., Nishibori, T., Yamamoto, K., Crites, S.T., Michikami, T. and Yokota, Y., 2017. Detection of intact lava tubes at marius hills on the moon by selene (kaguya) lunar radar sounder. Geophysical Research Letters, 44(20). [7] Cushing, G.E., 2012. Candidate cave entrances on Mars. Journal of Cave and Karst Studies, 74(1): 33-47

With some exceptions, the deep fractured rock ecosystems across most of North America have not been studied extensively. However, the US Great Basin, in particular the Nevada National Security Site (NNSS, formerly the Nevada Test Site), has hosted a number of influential subsurface investigations over the years. This study focuses on resident microbiota within the fluids extracted from monitoring borehole U-3cn#5 at a depth of 691 meters below land surface, which intercepts a hydrogeological confined aquifer within Paleozoic fractured carbonate rocks. Analysis of the microorganisms living in this oligotrophic environment provides a perspective into microbial metabolic strategies required to endure prolonged hydrogeological isolation deep underground. Here we present a microbiological and physicochemical characterization of this environment and describe a novel bacterial genus isolated from the ecosystem. Strain DRI-13T is a strictly anaerobic, moderately thermophilic, fumarate-respiring member of the phylum Firmicutes. This bacterium grows optimally at 55°C and pH 8.0, can tolerate a concentration of 100 mM NaCl, and appears to obligately metabolize fumarate to acetate and succinate. Culture-independent 16S rRNA gene sequencing indicates a global subsurface distribution, while the closest cultured relatives of DRI-13T are Pelotomaculum thermopropionicum (90.0% similarity) and Desulfotomaculum gibsoniae (88.0% similarity). The predominant fatty acid profile is iso-C15:0, C15:0, C16:0 and C14:0. The percentage of the straight-chain fatty acid C15:0 is a defining characteristic not present in the other closely related species. The genome is estimated to be 3,649,665 bp, composed of 87.3% coding regions with an overall average of 45.1% G+C content. Strain DRI-13T represents a novel genus of subsurface bacterium isolated from a previously uncharacterized rock-hosted geothermal habitat. Our results describe a novel genus of bacterium combined with sequenced genome that provides insights into metabolism strategies of the deep subsurface biosphere. Based on our characterization analysis we propose the name Thermoanaerosceptrum fracticalcis (DRI-13T = DSM 100382T = ATCC TSD-12T).

Digital elevation models generated with SAR interferometry (InSAR) are an important information source for glacier and ice sheet mass balance. However, the measured elevations suffer from a penetration bias due to the interferometric phase center being up to several tens of meters below the surface. The penetration of the microwave signals depends on SAR parameters (e.g. frequency) and snow and ice conditions. There is potential to estimate this penetration bias directly from the data by means of polarimetric InSAR models. Existing models fail to describe the data across different test sites and ice conditions and phase centers were found to be deeper than predicted by these models. SAR tomography is employed to assess the vertical distribution of backscattering in the data from an airborne campaign. The data are compared to refined models in order to find better representations of the vertical backscattering distribution, while the model complexity is purposely kept simple to make a phase center estimation possible. Additionally, recent work showed the importance of strong subsurface layers which influence phase center depth. Combining the refined subsurface structure models and dominant subsurface layers allows simulating a variety of ice sheet subsurface scenarios and can be used to assess the potential to estimate the InSAR phase center depth directly from the data.

The need of large scale observations with high temporal frequency has promoted airborne and satellite remote sensing techniques for glaciological applications. In particular, active microwave sensors, such as synthetic aperture radars (SARs), offer all-weather and daylight independent operability which is of great advantage at high latitudes, where extreme environmental conditions and long period of darkness strongly limit other kinds of sensors. Moreover, longer wavelengths allow to penetrate significantly into dry snow and ice, interacting with surface as well as subsurface features. On the one hand, this makes SAR measurements suitable to investigate the subsurface structure of glaciers and ice sheets. On the other hand, the complex interaction of microwaves with the subsurface layers makes the interpretation of SAR measurements challenging. This study investigates the potential of SAR techniques to retrieve information about glacier subsurface. SAR polarimetry and tomography are used to gain a 3-D characterization of the scattering scenario of the K-transect, a site located in the ablation zone of Greenland. For this, a fully-polarimetric tomographic airborne dataset, acquired by the DLR’s F-SAR system in the frame of the ARCTIC15 campaign, is exploited.

The exploration of the deep biosphere continues to reveal a great diversity of microorganisms, many of which remain poorly understood. This study provides a first look at the microbial community composition of the Costa Rica Margin sub-seafloor from two sites on the upper plate of the subduction zone, between the Cocos and Caribbean plates. Despite being in close geographical proximity, with similar lithologies, both sites show distinctions in the relative abundance of the archaeal domain and major microbial phyla, assessed using a pair of universal primers and supported by the sequencing of six metagenomes. Elusimicrobia, Chloroflexi, Aerophobetes, Actinobacteria, Lokiarchaeota, and Atribacteria were dominant phyla at Site 1378, and Bathyarchaeota, Chloroflexi, Hadesarchaeota, Aerophobetes, Elusimicrobia, and Lokiarchaeota were dominant at Site 1379. Correlations of microbial taxa with geochemistry were examined and notable relationships were seen with ammonia, sulfate, and depth. With deep sediments, there is always a concern that drilling technologies impact analyses due to contamination of the sediments via drilling fluid. Here, we use analysis of the drilling fluid in conjunction with the sediment analysis, to assess the level of contamination and remove any problematic sequences. In the majority of samples, we find the level of drilling fluid contamination, negligible.

Board of governors conference "Bodem en Ondergrond" (Bestuurlijke conferentie Bodem en Ondergrond). Omgevingsdienst West-Holland organized the conference to discuss the use and future possibilities for use of the subsurface and the problems associated with using the subsurface. The geology of the subsurface in the area of the Omgevingsdienst West-Holland is not very promising. Oil & gas discoveries are limited and mostly not economic and also for geothermal energy the geology seems not optimum. Seasonal Thermal Energy Storage (STES) on varying depth is already used and likely to be used extensively in the near future. The geology of the area is reasonably known due to the oil & gas exploration, but still very limited certainly on larger depth. Many problems occur in geothermal installations due to aggressive water that corrodes pipes, installations and also degrades the permeability characteristics of the reservoir rock. The risks of geothermal energy are large and often the preliminary investigations are limited and consultants, project developers and owners of projects have limited or insufficient knowledge on geology. STES when extensively used may have implications for near surface groundwater and ground temperatures. A major problem in the area of West-Holland is the peat oxidation that may require serious changes in land use to be reduced.

Board of governors conference "Bodem en Ondergrond" (Bestuurlijke conferentie Bodem en Ondergrond). Omgevingsdienst West-Holland organized the conference to discuss the use and future possibilities for use of the subsurface and the problems associated with using the subsurface. The geology of the subsurface in the area of the Omgevingsdienst West-Holland is not very promising. Oil & gas discoveries are limited and mostly not economic and also for geothermal energy the geology seems not optimum. Seasonal Thermal Energy Storage (STES) on varying depth is already used and likely to be used extensively in the near future. The geology of the area is reasonably known due to the oil & gas exploration, but still very limited certainly on larger depth. Many problems occur in geothermal installations due to aggressive water that corrodes pipes, installations and also degrades the permeability characteristics of the reservoir rock. The risks of geothermal energy are large and often the preliminary investigations are limited and consultants, project developers and owners of projects have limited or insufficient knowledge on geology. STES when extensively used may have implications for near surface groundwater and ground temperatures. A major problem in the area of West-Holland is the peat oxidation that may require serious changes in land use to be reduced.

The deep subsurface of other planetary bodies is of special interest for robotic and human exploration. The subsurface provides access to planetary interior processes, thus yielding insights into planetary formation and evolution. On Mars, the subsurface might harbour the most habitable conditions. In the context of human exploration, the subsurface can provide refugia for habitation from extreme surface conditions. We describe the fifth Mine Analogue Research (MINAR 5) programme at 1 km depth in the Boulby Mine, UK in collaboration with Spaceward Bound NASA and the Kalam Centre, India, to test instruments and methods for the robotic and human exploration of deep environments on the Moon and Mars. The geological context in Permian evaporites provides an analogue to evaporitic materials on other planetary bodies such as Mars. A wide range of sample acquisition instruments (NASA drills, Small Planetary Impulse Tool (SPLIT) robotic hammer, universal sampling bags), analytical instruments (Raman spectroscopy, Close-Up Imager, Minion DNA sequencing technology, methane stable isotope analysis, biomolecule and metabolic life detection instruments) and environmental monitoring equipment (passive air particle sampler, particle detectors and environmental monitoring equipment) was deployed in an integrated campaign. Investigations included studying the geochemical signatures of chloride and sulphate evaporitic minerals, testingAnalog researchastrobiologyMarssubsurfacetechnology methods for life detection and planetary protection around human-tended operations, and investigations on the radiation environment of the deep subsurface. The MINAR analogue activity occurs in an active mine, showing how the development of space exploration technology can be used to contribute to addressing immediate Earth-based challenges. During the campaign, in collaboration with European Space Agency (ESA), MINAR was used for astronaut familiarization with future exploration tools and techniques. The campaign was used to develop primary and secondary school and primary to secondary transition curriculum materials on-site during the campaign which was focused on a classroom extra vehicular activity simulation., We thank the Science and Technology Facilities Council (STFC) for their support of the Boulby Underground Science Facility in which MINAR5wasconducted. Knowledge gainedin the execution of STFC grant, ST/M001261/1, was used to advance objectives in MINAR 5. We thankCleveland Potash and ICL for their generous in-kind and logistics supportto MINAR and the underground science facility with which MINAR is made possible.Boris Laurent is funded by a Leverhulme Trust Research Project Grant, RPG-2016-071. SPLIT Research and Developmenthas been fundedby three research grants (UKSA CREST and STFC’s Follow on Fund) between 2013 and 2017, with support in 2018 by CREST to realise a TRL 5 flight type prototype instrument.Jon Telling (gas analysis development) is funded in part by UK Space Agency grant ST/R001421/

Diverse micro-organisms populate a global deep biosphere hosted by rocks and sediments beneath land and sea, containing more biomass than any other biome except forests. This paper reviews an emerging palaeobiological archive of these dark habitats: microfossils preserved in ancient pores and fractures in the crust. This archive, seemingly dominated by mineralized filaments (although rods and coccoids are also reported), is presently far too sparsely sampled and poorly understood to reveal trends in the abundance, distribution, or diversity of deep life through time. New research is called for to establish the nature and extent of the fossil record of Earth's deep biosphere by combining systematic exploration, rigorous microanalysis, and experimental studies of both microbial preservation and the formation of abiotic pseudofossils within the crust. It is concluded that the fossil record of Earth's largest microbial habitat may still have much to tell us about the history of life, the evolution of biogeochemical cycles, and the search for life on Mars.

In 2008, as part of a feasibility study for radioactive waste disposal in deep geological formations, the French National Radioactive Waste Management Agency (ANDRA) drilled several boreholes in the transposition zone in order to define the potential variations in the properties of the Callovo&ndash, Oxfordian claystone formation. This consisted of a rare opportunity to investigate the deep continental biosphere that is still poorly known. Four rock cores, from 1709, 1804, 1865, and 1935 m below land surface, were collected from Lower and Middle Triassic formations in the Paris Basin (France) to investigate their microbial and geochemical composition. Rock leachates showed high salinities ranging from 100 to 365 g&middot, L&minus, 1 NaCl, current temperatures averaging 65 &deg, C, no detectable organic matter, and very fine porosity. Microbial composition was studied using a dual cultural and molecular approach. While the broad-spectrum cultural media that was used to activate microbial communities was unsuccessful, the genetic investigation of the dominant 16S rRNA gene sequences revealed eight bacterial genera considered as truly indigenous to the Triassic cores. Retrieved taxa were affiliated to aerobic and facultative anaerobic taxon, mostly unknown to grow in very saline media, except for one taxon related to Halomonas. They included Firmicutes and &alpha, &beta, and &gamma, Proteobacteria members that are known from many subsurface environments and deep terrestrial and marine ecosystems. As suggested by geochemical analyses of rocks and rock leachates, part of the indigenous bacterial community may originate from a cold paleo-recharge of the Trias aquifer with water originating from ice melting. Thus, retrieved DNA would be fossil DNA. As previously put forward to explain the lack of evidence of microbial life in deep sandstone, another hypothesis is a possible paleo-sterilisation that is based on the poly-extremophilic character of the confined Triassic sandstones, which present high salinity and temperature.