Surface Outcrops Research Articles

Active seismic surveys for drilling target characterization in Ossola Valley: International Continental Scientific Drilling Program (ICDP) project Drilling the Ivrea–Verbano zonE (DIVE) phase I

Abstract. 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.

Enhanced structural analysis through a hybrid analogue-digital mapping approach: Integrating field and UAV survey with microtomography to characterize metamorphic rocks

This study focused on collecting structural data orientations of a crustal-scale shear zone (Palmi Shear Zone, PSZ, southern Calabria, Italy) by integrating various analytical and field-based techniques. The PSZ consists of deformed metamorphic rocks (migmatitic biotitic paragneiss, marbles, and skarns) showing multiple folding phases, and Hercynian tonalites and pegmatites (306-290 Ma), crosscut by Late Hercynian leucocratic dykes (ca. 290 Ma). Multi-sized clasts composed of different lithologies are preserved on clean outcrop surfaces, and are sheared into both σ - and δ -type objects that collectively suggest opposing senses of shear. The study incorporates structural analysis of folds, field and aerial surveys (UAV), digital mapping, and microcomputed tomography. Various kinematic indicators were observed in the PSZ, indicating a mix of factors influencing the shear strain patterns (e.g. fold interference patterns, different rock types with high viscosity contrast). The findings suggest a clear consistency between structural data inferred from 3D VOM (Virtual Outcrop Model) and those collected directly in the field, confirming the occurrence of both sinistral and dextral shear in the PSZ, providing important insights into the tectonic evolution of the Calabrian-Peloritani Terrane.

The Palaeozoic of a future high potential hydrocarbon fold-thrust belt through the Zagros Basin, Iran

The Zagros Fold-and-Thrust Belt is one of the world's richest hydrocarbon regions, with Palaeozoic sediments being a key element in hydrocarbon plays. The main aim of this research is to provide a model for the formation and development of the sedimentary basin during the Palaeozoic Era in the Zagros and Persian Gulf regions. We utilize data from exploratory wells and surface outcrops of Palaeozoic sediments specifically in the northern parts of Iran's Zagros Mountains. The seismic profiles of the eastern region of the Persian Gulf provide more detailed information due to their distance from the Zagros hinterland. The investigation reveals that folds with wavelengths of several tens of km were formed on the Infra-Cambrian Hormuz Salt or its equivalent décollement.This study has identified halokinetic activities as the primary cause of Palaeozoic deformations in the Zagros region, with tectonic and orogenic factors playing a secondary role. The Palaeozoic sediments are divided into pre-kinematic, syn-kinematic and post-kinematic categories. Sedimentary sequences possibly including the Palaeozoic hydrocarbon source rock could be present throughout the study area.

On the origin of alkali feldspar megacrysts in granitoids. Part 2: evidence for nucleation and growth under magmatic conditions from crystal size distributions of the Cathedral Peak Granodiorite, California, USA

The mechanisms whereby alkali feldspar megacrysts form have been debated for several decades; yet, we do not understand well the processes that lead to their formation. We take advantage of glacially polished outcrop surfaces from the Cathedral Peak Granodiorite in the Tuolumne Intrusive Complex, CA to quantitatively characterize alkali feldspar textures, to provide better insight into their origin. On the glacially polished surfaces, we traced alkali feldspar crystals > 10 mm in the field. From the same localities, we also collected large slabs and stained them to reveal feldspar textures for crystals < 20 mm in size. We scaned the resulting field tracings and rock slabs to quantify CSDs using image processing techniques with the software ImageJ. The CSDs from glacially polished outcrop surfaces and complementary polished and stained rock slabs reveal two stages of crystallization. Crystals > 20 mm show log-linear CSDs with shallow slopes, suggesting magmatic nucleation and growth on timescales of thousands of years. Crystals < 20 mm define a second stage of crystallization, with much steeper slopes, suggesting a period of enhanced nucleation leading to formation of a groundmass during the final stages of solidification on timescales of decades to centuries. We do not find any evidence for CSDs affected by textural coarsening, or any effects of subsolidus processes. Our data suggest that these megacrysts form in large, slowly cooling magma, where low nucleation rates dominate. These crystals are not special in their magmatic formation—only in their size. A change in solidification conditions led to the formation of a groundmass, which warrants further study to better understand this crystallization stage in a plutonic environment.

Estimation of the dolomite content of carbonate rock outcrops based on spectral knowledge and machine learning

Accurately estimating the dolomite content in carbonate rocks is crucial for optimizing oil and gas exploration and production strategies. Hyperspectral techniques for estimating dolomite content have advantages in terms of efficiency, cost-effectiveness, and non-destructiveness compared with traditional laboratory methods. Despite the abundance of hyperspectral data, feature selection and extraction remain challenging. In this study, hyperspectral data collected from surface outcrop in the field using the analytical spectral device (ASD) were applied to construct model for estimating dolomite content. Firstly, the data were preprocessed via outlier analysis and continuum transformation. Next, a hybrid approach integrating spectral knowledge with machine learning was proposed and applied to facilitate efficient and precise feature selection of the hyperspectral data; in this approach, preliminary screening based on spectral knowledge is followed by further hyperspectral data feature selection using a random forest algorithm. The selected features were then combined using a support vector regression algorithm to obtain the estimation model. Finally, the accuracy of the model was evaluated using the hyperspectral data from field outcrop samples. To further verify the effectiveness of this method, various combinations of eight input variables and four machine learning algorithms were compared. Among all combinations, our model achieved the highest accuracy with a test R2 value of 0.91 and a root-mean-square error of only 0.122. The proposed method is practical and efficient and provides precise quantitative data for field geologists to identify the mineral distribution in outcrops. Thus, our method provides robust support for understanding reservoir characteristics and has significant practical value in geological surveys and mineral exploration.

Response of preferential flow to soil − root − rock fragment system in karst rocky desertification areas

The response of preferential flow to the soil − root − rock fragment systems is essential for understanding the eco-hydrological processes in karst rocky desertification (KRD) areas. In this study, we investigated the soil properties, root, and rock fragment distribution characteristics and preferential flow in this system. Results show that there are differences in the development of preferential flow under five grades of rocky desertification: light rocky desertification (LRD) > potential rocky desertification (PRD) > non-rocky desertification (NRD) > moderate rocky desertification (MRD) > severe rocky desertification (SRD). Different degrees of rocky desertification have facilitating or inhibiting effects on preferential flow. LRD and PRD promote preferential flow with ratio of 6.6 %–9.6 %, while MRD and SRD inhibit preferential flow with ratio of 4.2 %–6.7 %. The preferential flow is simultaneously influenced by the components of soil − root − rock fragment systems. Root system indicators (i.e., root biomass, root bulk density, and root length density) generally decrease as grades of rocky desertification increase. The surface outcrops density, rock fragment density, and volume fraction tend to increase with grades of rocky desertification. A principal components analysis found that preferential flow of MRD and SRD is highly influenced by rock fragments, while LRD is more driven by root systems and soil properties. PRD is averagely influenced by the combination. These findings suggest that appropriate plant and rock fragment ratios can effectively avoid water loss in the form of preferential flow and more attention should be paid to the ecological problems of LRD and PRD areas.

Origin of a polymict, mega‐clast‐bearing impact breccia in the crater floor of Wetumpka Impact Structure, Elmore County, Alabama: Insights from surface outcrops and a drill core

ABSTRACTWetumpka impact structure is a Late Cretaceous, marine‐target impact crater of about 5 km diameter. The apparent crater rim is mostly made of crystalline local basement, and the apparent crater floor consists of a mixed sediments of target lithology. These sediments are the provenance of the crater‐filling impactite sands, overlying trans‐crater slide unit, and the capping polymict impact breccia deposit, often referred to by previous workers as “central polymict breccia.” The unit has been known to contain elongated mega‐clasts of up to tens of meters in size. This study attempted to understand the mode of emplacement of this polymict breccia, which occurs in some places on the apparent crater floor and resembles a polymict proximal ejecta deposit. This work also reports the first documentation of rare, potential impact spherules in the polymict impact breccia, interpreted to be a part of distal ejecta. The presence of large, decimeter‐sized clasts in the breccia can be best explained by the movement of overturned rim flap forming part of proximal ejecta from the crater rim to the apparent crater floor during early modification stage of impact cratering. Our work highlights the bimodal clast size distribution of the polymict breccia, and so we propose that the term “mega‐clast‐bearing impact breccia” be used for this unit. We attribute a generally steep orientation of the decameter sized clasts to primary imbrication during emplacement. The emplacement of this breccia is interpreted as associated with the ejecta emplacement process that occurred before the return of marine resurge.

Reservoir Characterization of the Paleogene Khurmala Formation in Tawke and Shaqlawa Areas, Kurdistan Region of Iraq

Well logs were utilized to investigate petrophysical properties of the Khurmala Formation’s surface outcrops in Shaqlawa Subdistrict and Tawke Oilfield, e.g., lithology, shale volume, porosity, and fracture. The thickness of the formation is about 15 m in the Shaqlawa section and 42 m in the Tawke Oilfield. Porosity logs were used to estimate porosity; where the porosity values reached a maximum of 52% from the sonic log, 48% from the density log, and 35% from the neutron porosity log. The reservoir quality of the Khurmala Formation, as determined through the analysis of thin sections, which were obtained from outcrop samples, is deemed to be of low quality. The determined shale volume within the examined interval exhibits a moderate level of clay constituents, with the highest gamma-ray measurement indicating a shale content of 29% at some locations within the reservoir. This integrated method using various conventional well logs suggests a great probability of petrophysical properties in the Khurmala Formation to be considered as the reservoir.

Linking northeastern North Pacific oxygen changes to upstream surface outcrop variations

Abstract. Understanding the response of the ocean to global warming, including the renewal of ocean waters from the surface (ventilation), is important for future climate predictions. Oxygen distributions in the ocean thermocline have proven an effective way to infer changes in ventilation because physical processes (ventilation and circulation) that supply oxygen are thought to be primarily responsible for changes in interior oxygen concentrations. Here, the focus is on the North Pacific thermocline, where some of the world's oceans' largest oxygen variations have been observed. These variations, described as bi-decadal cycles on top of a small declining trend, are strongest on subsurface isopycnals that outcrop into the mixed layer of the northwestern North Pacific in late winter. In this study, surface density time series are reconstructed in this area using observational data only and focusing on the time period from 1982, the first full year of the satellite sea surface temperature record, to 2020. It is found that changes in the annual maximum outcrop area of the densest isopycnals outcropping in the northwestern North Pacific are correlated with interannual oxygen variability observed at Ocean Station P (OSP) downstream at about a 10-year lag. The hypothesis is that ocean ventilation and uptake of oxygen is greatly reduced when the outcrop areas are small and that this signal travels within the North Pacific Current to OSP, with 10 years being at the higher end of transit times reported in other studies. It is also found that sea surface salinity (SSS) dominates over sea surface temperature (SST) in driving interannual fluctuations in annual maximum surface density in the northwestern North Pacific, highlighting the role that salinity may play in altering ocean ventilation. In contrast, SSS and SST contribute about equally to the long-term declining surface density trends that are superimposed on the interannual cycles.

Runoff generation and erosion processes at the rock–soil interface of outcrops with a concave surface in a rocky desertification area

Rock surface flow, originating from outcrop surfaces during rainfall, represents a distinctive form of runoff influencing surface erosion and subsurface soil leakage in karst rocky desertification areas. Despite their significance, the processes governing runoff generation and erosion at the rock–soil interface (RSI) under the influence of rock surface flow remain poorly understood. This study aims to elucidate the generation and transformation of runoff at the RSI, along with their scouring erosion effects influenced by rock surface flow from concave-shaped outcrops. Artificial rainfall experiments were conducted on simulated rock–soil structural units featuring exposed rock surfaces and unexposed RSIs of outcrops with concave shapes. Two driving factors, namely rainfall intensity (R) and the inclination of the rock surface (IRS), were manipulated to investigate the formation and output processes of runoffs and sediments from the surface, RSI, and non-RSI (a site away from the RSI). The presence of an exposed rock surface altered the distribution pattern of rainfall–infiltration–runoff. An increase in the IRS led to a significant decrease in surface runoff (p < 0.05). When the IRS was close to vertical, the rainfall-runoff was primarily in the form of surface runoff; however, for inclinations less than 90°, the primary contributors to rainfall-runoff were the RSI and non-RSI runoffs. Surface soil erosion emerged as the predominant form of soil loss, with runoff yield demonstrating a linear positive correlation with sediment production. Both the IRS and R were identified as significant factors affecting surface runoff and soil erosion. Notably, when the IRS was less than 45°, the total soil loss reached its minimum. Therefore, runoff generation at the RSI led to a reduction in surface runoff and an increase in subsurface runoff, contributing to soil leakage at the RSI. Nevertheless, surface erosion remained the primary mechanism of soil loss.

Nondestructive geochemical characterization of fossil hominin taphonomy and burial history

To date, only three Homo habilis specimens have been discovered that have associated craniodental and postcranial elements, providing a limited fossil record of the ontogeny and morphology of early members of the genus Homo. Recently, a nearly complete dentition, likely attributable to H. habilis, was discovered and excavated from early Pleistocene-age fluvial-lacustrine sediments of the upper Burgi Member of the Koobi Fora Formation at site F25787 in Area 13, near Ileret, Kenya. On the surface less than 15 m away, at site F25966, postcranial elements were found, which, if from the same individual as the nearby dentition, would represent the fourth associated craniodental and postcranial assemblage of this species. We developed a geochemical taphonomic history of these ca. 2 Ma hominin fossils using nondestructive X-ray based microanalytical tools (synchrotron and benchtop X-ray fluorescence chemical imaging and micro- and nano-computed tomography volumetric reconstruction), bulk analyses of sediments and paleosols at the excavation sites, and sedimentologic and stratigraphic observations. We integrate the chemical and physical taphonomic histories to test whether teeth (excavated in situ) and postcranial bones (eroded onto the outcrop surface) derive from a single individual. Minor differences in taphonomic history are attributable to the different biomineral properties of the dental and osseous components and to differences in physical damage during early post-mortem scavenging, dispersal, and burial in adjacent depositional settings. Microscale geochemical mapping enabled the temporal ordination of chemical and physical events in the specimens’ chemical taphonomic histories. Specifically, authigenic Fe- and K-bearing clays and Y, U, and Sr uptake occurred in post-burial fractures in bones and were also incorporated pervasively throughout dentin in teeth. Barite mineralization occurred along the latest fractures in both materials, and as a coating on tooth roots. The stratigraphic, taphonomic, and geochemical evidence supports the interpretation that the hominin fossils represent a single individual. Successful application of these nondestructive sample characterization methods demonstrates capabilities for thorough interrogation of the taphonomic histories of other potential hominin fossil associations, enabling more robust and accurate palaeontologic constraints using those relationships.

Probing the exchange of CO2 and O2 in the shallow critical zone during weathering of marl and black shale

Abstract. Chemical weathering of sedimentary rocks can release carbon dioxide (CO2) and consume oxygen (O2) via the oxidation of petrogenic organic carbon and sulfide minerals. These pathways govern Earth's surface system and climate over geological timescales, but the present-day weathering fluxes and their environmental controls are only partly constrained due to a lack of in situ measurements. Here, we investigate the gaseous exchange of CO2 and O2 during the oxidative weathering of black shales and marls exposed in the French southern Alps. On six field trips over 1 year, we use drilled headspace chambers to measure the CO2 concentrations in the shallow critical zone and quantify CO2 fluxes in real time. Importantly, we develop a new approach to estimate the volume of rock that contributes CO2 to a chamber, and assess effective diffusive gas exchange, by first quantifying the mass of CO2 that is stored in a chamber and connected rock pores. Both rock types are characterized by similar contributing rock volumes and diffusive movement of CO2. However, CO2 emissions differed between the rock types, with yields over rock outcrop surfaces (inferred from the contributing rock volume and the local weathering depths) ranging on average between 73 and 1108 tCkm-2yr-1 for black shales and between 43 and 873 tCkm-2yr-1 for marls over the study period. Having quantified diffusive processes, chamber-based O2 concentration measurements are used to calculate O2 fluxes. The rate of O2 consumption increased with production of CO2, and with increased temperature, with an average O2:CO2 molar ratio of 10:1. If O2 consumption occurs by both rock organic carbon oxidation and carbonate dissolution coupled to sulfide oxidation, either an additional O2 sink needs to be identified or significant export of dissolved inorganic carbon occurs from the weathering zone. Together, our findings refine the tools we have to probe CO2 and O2 exchange in rocks at Earth's surface and shed new light on CO2 and O2 fluxes, their drivers, and the fate of rock-derived carbon.

Surface occurrence of dawsonite and natural CO2 emanation in Covasna, in the Eastern Carpathians: A stable isotope study

Dawsonite (NaAlCO3(OH)2) is widely known as a CO2 trapping mineral during the geological storage of CO2 (Carbon Capture and Storage). Dawsonite can occur naturally in various geological environments, however only few surface occurrences are known. The Covasna area (Eastern Carpathians) gives an excellent opportunity to study dawsonite in surface outcrop in the Hankó Valley and extend our knowledge about the possible precipitation environments of dawsonite. Based on the detailed petrographic and geochemical investigations of the rock and water samples from this area, formation environment of dawsonite and the concomitant mineral assemblage (e.g. alumohydrocalcite) were constrained. Based on our results, dawsonite and alumohydrocalcite formed at low temperature (7.6–20 °C). Utilizing the stable carbon, oxygen and hydrogen isotope composition of dawsonite separates (δ13CDaw: +8.0 − +10.1 ‰, δ18ODaw: +40.7 − +46.7 ‰, δ2HDaw: −55 - -42 ‰), the isotopic composition of the parental fluid was determined. Our results indicate that the dawsonite formed from a CO2 source, which has mantle origin. In addition, H2O which was present during the formation of dawsonite, had similar hydrogen isotope composition to recent spring waters, whereas the oxygen isotope composition is characterized by more positive values. This oxygen shifts relative to Global Meteoric Waterline might be related to water-rock interaction or contribution of metamorphic/magmatic water and oxygen isotope exchange between H2O and CO2.

3‐D geophysical modeling of a buried, simple impact crater: Holleford impact structure, Ontario, Canada

AbstractHolleford Crater is a deeply buried, 2.35 km diameter late Proterozoic‐early Cambrian (550 ± 50 Ma) simple impact crater located in southeastern Ontario, Canada. Exploration drilling in the 1950–60s indicated a &gt;450 m deep, simple impact structure with an infill stratigraphy of Cambro‐Ordovician clastic and carbonate sediments and a −2.2 mGal gravity anomaly. We conducted new ground‐based geophysical surveys (magnetics, gravity) and potential field modeling to better resolve the buried impact structure depth, subsurface geometry, and postimpact modification. Geophysical surveys reveal a well‐defined ~3 mGal Bouguer gravity low and &lt;20 nT residual magnetic anomaly over the crater basin. The lack of a well‐defined magnetic anomaly is due to the low magnetic contrast between Mesoproterozoic metasedimentary target rocks and Paleozoic infill sediments. The modeled basement surface shows a deeply buried (&gt;400 m), eroded simple impact structure with a rim‐to‐rim diameter (D) of 1.8–2 km, a residual rim height of about 30 m and a true depth (dt) &gt;400 m. The modeled diameter is smaller than the previous estimate (2.35 km) based on the surface outcrop pattern of Paleozoic strata, which overestimates the buried impact structure dimensions. The modeled basement surface identifies a rim breach and a possible fluvial outflow channel in the southeast impact structure rim. The channel is up to 150 m deep and 400 m in width and has morphology similar to outlet channels produced by fluvial rim dissection of terrestrial impact structures and “tadpole craters” on Mars.

Uranium distribution in the promise reefs of the Mesoarchean Westrand Group, Witwatersrand Supergroup, South Africa

The Mesoarchean Westrand Group (2932 – 2923 Ma) constitutes the lower portion of the Witwatersrand Supergroup. Compared to the overlying Central Rand Group which is well known for its world-class conglomerate-hosted gold-uranium deposits, the economic potential of palaeoplacers in the Westrand Group has not been fully explored. This study aims to assess the uranium potential of the Promise Reefs in the Westrand Group. Field exposures of the Promise Reefs and boreholes drilled down-dip from the surface outcrops were investigated in the Westrand area. Three reef zones were recognized consisting of well-mineralized, matrix-to clast-supported, small pebble conglomerates with associated medium- to coarse-grained quartzite.Radioactive minerals found in the conglomerates comprise leucoxene, brannerite, carbon nodules, monazite, allanite, thorite, and uraninite.Analyses of U and Th from borehole samples reported mean values of 120 ppm for U and 60 ppm for Th. Maximum U and Th concentrations are 630 ppm and 125 ppm, respectively. The highest U/Th ratio was 17.4 with a mean value of 2. The conglomerates from surface outcrops have maximum U and Th concentrations of 111 ppm and 140 ppm, respectively, with a mean U value of 19.5 ppm and a mean Th value of 26.6 ppm, and a mean U/Th ratio of 0.6. Comparison of the data shows that surface outcrops generally report lower U concentrations than their unweathered equivalents.Also, U assays by γ-spectrometry and INAA of the same samples from surface outcrops yielded inconsistent results. As U exploration by field γ-spectrometry relies on the existence of 234U/238U equilibrium and because of the U depletion in the surface samples, further investigations using α-spectrometry and Pb-isotope analyses were employed.The results obtained from α-spectrometry point to complex U redistribution processes in the surface conglomerate with several stages of uranium loss and/or gain. The bulk of the U was removed during an early stage of surface exposure and supergene alteration, probably more than 1.4 Ma ago.The estimation of the original pre-weathering U concentration in the surface conglomerates is based on the measured Pb-isotope ratios 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb and the Pb and Th concentrations. The data were inserted into U-Th-Pb age equations which were reformulated and solved for the U concentrations. To test the method, for a suite of borehole samples the same treatment was applied. The calculated fresh-rock U tenor indicates the occurrence of supergene uranium losses which are of the same magnitude as the U losses caused by experimental leaching of fresh conglomerate samples. The high amount of radiogenic Pb found in the surface samples points to severe uranium losses earlier than 100 Ma ago.The data show that U redistribution in weathered Mesoarchean conglomerates is not governed by systematic processes which obscure the original pre-weathering U concentration. Application of the Pb isotope technique proves to be the only method yielding usable estimates of the fresh-rock uranium tenor in deeply weathered terranes.

Lithostratigraphy of a portion of the Neoproterozoic Rosh Pinah formation: Host rocks of the Western Orefield, Rosh Pinah mine, southern Namibia

The Rosh Pinah Zn–Pb–Ag deposit in southern Namibia comprises a significant sulphidic Zn–Pb resource (19.94 Mt @ 7.3 wt% Zn, 1.83 wt% Pb and 27.7 g/t Ag) occurring mainly as sphalerite and galena. The ore minerals as well as pyrite are hosted by the Ore Equivalent Horizon (OEH), a part of the Neoproterozoic Rosh Pinah Formation. Details on original rock types and depositional environment of the OEH units remain unclear despite past work. Here, we combine detailed drillhole logging data, drillhole logging database and drillcore photographs, underground and near-mine outcrop observations coupled with detailed petrographic observations to elucidate original rock types and depositional environments. The OEH is comprised of three mappable lithofacies (carbonaceous argillite and siltstones, volcanic/volcaniclastic rocks, and carbonate rocks) enclosed within a sequence of arkose. The lateral transition from coarse-grained arkose to the fine-grained carbonaceous rocks of the OEH reflects subaqueous fan type deposition. The presence of diagenetic textures in the carbonate rocks in form of cloudy, isopachous fibrous dolomitic cements point to subaqueous depositional environments. The geometry of carbonate bodies in the OEH at the Rosh Pinah mine and in nearby surface outcrop exposures suggest local accumulations with a pronounced topographic relief above the surrounding sediments, reminiscent of carbonate buildups. The OEH appears to represent a limited interval of marine or lacustrine deposition that may be related to syn-sedimentary extensional conditions.

Science and Science‐Enabling Activities of the SHERLOC and WATSON Imaging Systems in Jezero Crater, Mars

AbstractDuring its first year of operation, the Perseverance rover explored the cratered and fractured floor of Jezero crater on Mars. Here, we report the use of the Scanning Habitability Environments with Raman and Luminescence for Organics and Chemicals (SHERLOC) imaging system that includes two high‐resolution cameras, the Autofocus and Contextual Imager (ACI) and Wide Angle Topographic Sensor for Operations and eNgineering (WATSON). ACI is a fixed focus gray scale imager with a resolution of 10.1 μm/pixel whereas WATSON is a variable field of view, variable focus imager capable of resolution down to 14 μm/pixel. WATSON is a reflight of the MArs Hand Lens Imager (MAHLI) imager and has similar capabilities. During first‐time activities, WATSON was used to support both science and engineering operations related to sample and abrasion patch assessment and sample collection and caching. WATSON also documented the deployment of the Ingenuity helicopter. The Crater Floor Campaign identified two primary rock units, the Máaz formation and the Séítah formation, which have been interpreted as lava flows and an olivine cumulate, respectively. Interpretation of rock textures with WATSON and ACI images was limited to abraded surfaces because unmodified outcrop surfaces (herein termed “natural surfaces”) show high degrees of dust covering, wind abrasion, and coating by secondary mineral products. WATSON and ACI images support the hypothesis that the material of both the Máaz and Séítah formations consists of largely aqueously altered mafic materials with varying igneous origins.

The competition between anthropogenic aerosol and greenhouse gas climate forcing is revealed by North Pacific water-mass changes.

Modeled water-mass changes in the North Pacific thermocline, both in the subsurface and at the surface, reveal the impact of the competition between anthropogenic aerosols (AAs) and greenhouse gases (GHGs) over the past 6 decades. The AA effect overwhelms the GHG effect during 1950-1985 in driving salinity changes on density surfaces, while after 1985 the GHG effect dominates. These subsurface water-mass changes are traced back to changes at the surface, of which ~70% stems from the migration of density surface outcrops, equatorward due to regional cooling by AAs and subsequent poleward due to warming by GHGs. Ocean subduction connects these surface outcrop changes to the main thermocline. Both observations and models reveal this transition in climate forcing around 1985 and highlight the important role of AA climate forcing on our oceans' water masses.

An Approach for Monitoring Shallow Surface Outcrop Mining Activities Based on Multisource Satellite Remote Sensing Data

Monitoring mine activities can help management track the status of mineral resource exploration and mine rehabilitation. It is crucial to the sustainable development of the mining industry and the protection of the geological environment in mining areas. To monitor the mining activities of shallow surface outcrops in the arid and semi-arid regions of northwest China, this paper proposes a remote sensing monitoring approach of mining activities based on deep learning and integrated interferometric synthetic aperture radar technique. This approach uses the DeepLabV3-ResNet model to identify and extract the spatial location of the mine patches and then uses object-oriented analysis and spatial analysis methods to optimize the mine patch boundaries. SBAS-InSAR technique is used to obtain the time-series deformation information of the mine patches and is combined with the multi-temporal optical imagery to analyze the mining activities in the study area. The proposed approach has a recognition accuracy of 95.80% for the identification and extraction of mine patches, with an F1-score of 0.727 at the pixel level, and the average area similarity for all patches is 0.78 at the object-oriented level. The proposed approach possesses the capability to analyze mining activities, indicating promising prospects for engineering applications. It provides a reference for monitoring mining activities using multisource satellite remote sensing.

Seepage Analysis in Construction of Ciuyah Tunnel, Lebak, Banten, Indonesia

The Ciuyah Tunnel is 1,329 meters long, with excavation progress reaching 720 meters from the inlet and 120 meters from the outlet. However, the excavation process from the inlet had to be stopped because of groundwater leakage. Groundwater management has become essential in reducing this tunnel project’s environmental disasters. Seepage analysis is needed to determine the potential leaks in the following excavation process. So the determination of handling methods for leaks and the impact of leaks can be anticipated. The objective of this study is to identify how groundwater leakage occurs during excavation based on the characteristics of the rock masses on the tunnel excavation faces and surface outcrops. This study also predicts the potential seepage point in unexcavated sections. The results show that the tunnel construction area consists of slightly to moderately weathered intercalated tuffaceous sandstone and claystone with many discontinuities. The groundwater leakage on the inlet side occurred due to excavation cutting the discontinuities on the roof. While at the outlet side, it is influenced by syncline geometry and joint planes. The potential for seepage points can occur at excavation points that affect the geometry of the fold where the water goes to a lower place.