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Identifies core journals in environmental geology and explores facets of interdisciplinarity to consider the visibility of this field to collection-development librarians. Intercitation analysis of citing and cited patterns in 1995 articles revealed the journal network of environmental geology. Titles clustered into three categories: Engineering/Materials; Geochemical; and Water/Soil. (Author/AEF)

Abstract: The crystal structure and bonding environment of K2Ca(CO3)2 bütschliite were probed under isothermal compression via Raman spectroscopy to 95 GPa and single crystal and powder X-ray diffraction to 12 and 68 GPa, respectively. A second order Birch-Murnaghan equation of state fit to the X-ray data yields a bulk modulus, $${K}_{0}=46.9$$ K 0 = 46.9 GPa with an imposed value of $${K}_{0}^{\prime}= 4$$ K 0 ′ = 4 for the ambient pressure phase. Compression of bütschliite is highly anisotropic, with contraction along the c-axis accounting for most of the volume change. Bütschliite undergoes a phase transition to a monoclinic C2/m structure at around 6 GPa, mirroring polymorphism within isostructural borates. A fit to the compression data of the monoclinic phase yields $${V}_{0}=322.2$$ V 0 = 322.2  Å3$$,$$ , $${K}_{0}=24.8$$ K 0 = 24.8 GPa and $${K}_{0}^{\prime}=4.0$$ K 0 ′ = 4.0 using a third order fit; the ability to access different compression mechanisms gives rise to a more compressible material than the low-pressure phase. In particular, compression of the C2/m phase involves interlayer displacement and twisting of the [CO3] units, and an increase in coordination number of the K+ ion. Three more phase transitions, at ~ 28, 34, and 37 GPa occur based on the Raman spectra and powder diffraction data: these give rise to new [CO3] bonding environments within the structure.

Sedimentary basins provide a deep time archive of tectonic and Earth-surface processes that can be leveraged by detrital mineral U-Pb dating and geochemistry to track paleogeography, magmatism, and crustal evolution. Zircon preserves the long-term (billions of years) record of supercontinent cycles; however, it is biased toward preserving felsic crustal records. Detrital rutile complements the detrital zircon record by providing constraints on the time and temperature of rifting and mafic magmatism, metamorphism, exhumation of the middle and lower crust, subduction, and amagmatic orogenesis. We use detrital zircon U-Pb and detrital rutile U-Pb geochronology and trace element analysis of Permian to Eocene siliciclastic rocks in the southern Pyrenees to capture supercontinent cycles of ocean basins opening and closing. Detrital rutile age spectra show peaks at ca. 100 Ma associated with rifting and hyperextension in the Pyrenean realm, 200 Ma associated with the Central Atlantic Magmatic Province, and 330 Ma, 375 Ma, and 400 Ma associated with subduction and Rheic Ocean crust formation. Zr-in-rutile thermometry and rutile Cr-Nb systematics provide further insight into metamorphic facies (peak metamorphic temperatures) and source rock lithology (mafic versus felsic affinity). Detrital zircon age spectra have peaks at ca. 300 Ma, 450 Ma, and 600 Ma associated with major orogenic events and felsic magmatism, and Th/U ratios provide information on relative zircon formation temperatures. Comparison of these independent records shows that detrital rutile reflects rifting, magma-poor orogenesis, and oceanic lithospheric processes, while detrital zircon detects continental lithospheric processes. Integrated detrital zircon and rutile data sets archive past geological events across multiple Wilson cycles.

Cave carbonate minerals are an important terrestrial paleoclimate archive. A few studies have explored the potential for applying carbonate clumped isotope thermometry to speleothems as a tool for constraining past temperatures. To date, most papers utilizing this method have focused on mass-47 clumped isotope values (Δ47) at a single location and reported that cave carbonate minerals rarely achieve isotopic equilibrium, with kinetic isotope effects (KIEs) attributed to CO2 degassing. More recently, studies have shown that mass-47 and mass-48 CO2 from acid digested carbonate minerals (Δ47 and Δ48) can be used together to assess equilibrium and probe KIEs. Here, we examined 44 natural and synthetic modern cave carbonate mineral samples from 13 localities with varying environmental conditions (ventilation, water level, pCO2, temperature) for (dis)equilibrium using Δ47-Δ48 values, in concert with traditional stable carbon (δ13C) and oxygen (δ18O) isotope ratios. Data showed that 19 of 44 samples exhibited Δ47-Δ48 values indistinguishable from isotopic equilibrium, and 18 (95 %) of these samples yield Δ47-predicted temperatures within error of measured modern temperatures. Conversely, 25 samples exhibited isotopic disequilibria, 13 of which yield erroneous temperature estimates. Within some speleothem samples, we find Δ47-Δ48 values consistent with CO2 degassing effects, however, the majority of samples with KIEs are consistent with other processes being dominant. We hypothesize that these values reflect isotopic buffering effects on clumped isotopes that can be considerable and cannot be overlooked. Using a Raleigh Distillation Model, we examined carbon and oxygen isotope exchange trajectories and their relationships with dual clumped isotope disequilibria. Carbon isotope exchange is associated with depletion of both Δ47 and Δ48 relative to equilibrium, while oxygen isotope exchange is associated with enrichment of both Δ47 and Δ48 relative to equilibrium. Cave rafts collected from proximate locations in Mexico exhibit the largest average departures from equilibrium (ΔΔ47¯ = −0.032 ± 0.007, ΔΔ48¯ = −0.104 ± 0.035, where ΔΔi is the measured value – the equilibrium value). This study shows how the Δ47-Δ48 dual carbonate clumped isotope framework can be applied to a variety of tcave carbonate mineral samples, enabling identification of isotopic equilibria and therefore quantitative application of clumped isotope thermometry for paleoclimate reconstruction, or alternatively, constraining the mechanisms of kinetic effects.

The long-standing assumption that aboveground plant litter inputs have a substantial influence on soil organic carbon storage (SOC) and dynamics has been challenged by a new paradigm for SOC formation and persistence. We tested the importance of plant litter chemistry on SOC storage, distribution, composition, and age by comparing two highly contrasting ecosystems: an old-growth coast redwood (Sequoia sempervirens) forest, with highly aromatic litter, and an adjacent coastal prairie, with more easily decomposed litter. We hypothesized that if plant litter chemistry was the primary driver, redwood would store more and older SOC that was less microbially processed than prairie. Total soil carbon stocks to 110 cm depth were higher in prairie (35 kg C m-2) than redwood (28 kg C m-2). Radiocarbon values indicated shorter SOC residence times in redwood than prairie throughout the profile. Higher amounts of pyrogenic carbon and a higher degree of microbial processing of SOC appear to be instrumental for soil carbon storage and persistence in prairie, while differences in fine-root carbon inputs likely contribute to younger SOC in redwood. We conclude that at these sites fire residues, root inputs, and soil properties influence soil carbon dynamics to a greater degree than the properties of aboveground litter.

ImportanceThe ability to detect extracellular environmental conditions is a fundamental property of all life forms. Because microbial two-component sensor systems convert information about extracellular conditions into biochemical information that controls their behaviors, we evaluated how two-component sensor systems evolved within the deep Earth across multiple sites where abiotic and biotic properties vary. We show that these sensor systems remain abundant in microbial consortia at all subterranean sampling sites and observe correlations between sensor system abundances and abiotic (dissolved organic carbon variation) and biotic (consortia diversity) properties. These results suggest that multiple environmental properties may drive sensor protein evolution and highlight the need for further studies of metagenomic and geochemical data in parallel to understand the drivers of microbial sensor evolution.

At a geologic CO2 sequestration (GCS) site, geologic uncertainty usually leads to large uncertainty in the predictions of properties that influence metrics for leakage risk assessment, such as CO2 saturations and pressures in potentially leaky wellbores, CO2/brine leakage rates, and leakage consequences such as changes in drinking water quality in groundwater aquifers. The large uncertainty in these risk-related system properties and risk metrics can lead to over-conservative risk management decisions to ensure safe operations of GCS sites. The objective of this work is to develop a novel approach based on dynamic risk assessment to effectively reduce the uncertainty in the predicted risk-related system properties and risk metrics. We demonstrate our framework for dynamic risk assessment on two case studies: a 3D synthetic example and a synthetic field example based on the Rock Springs Uplift (RSU) storage site in Wyoming, USA. Results show that the U.S. National Risk Assessment Partnership's Open Source Integrated Assessment Model (NRAP-Open-IAM) coupled with a conformance evaluation can be used to effectively quantify and reduce the uncertainty in the predictions of risk-related system properties and risk metrics in GCS.

Abstract: Venus' tectonic evolution is not well understood. Thousands of kilometers of possible subduction sites on Venus have been identified along networks of rift zone trenches called chasmata. Rift zones are strong candidates for tectonic recycling due to pre‐existing weaknesses in the lithosphere. Recently, peel‐back delamination (PBD) was proposed as a mechanism of regional‐scale lithospheric recycling initiated at Venusian rift zones (Adams et al., 2022, https://doi.org/10.1029/2022je007460). PBD occurs when the lithospheric mantle becomes sufficiently thick and negatively buoyant to decouple and peel away from the overlying crust remaining at the surface. Both positively and negatively buoyant lithosphere were shown to undergo buoyancy‐driven PBD, though delamination is inhibited by increasing positive plate buoyancy. In this study, we use 2D numerical models to verify that delamination can be initiated in thinner, more positively buoyant lithosphere than in models with no plume‐rift interactions. Our results show that plume‐induced PBD in positively buoyant plates is facilitated by the excess negative buoyancy in the lithospheric mantle and increasing plume buoyancy force, and it is inhibited by increasing crustal buoyancy and decreasing rift width. We propose an age‐progressive framework for delamination at rift zones, where young, thin plates require a larger plume buoyancy force to be destabilized than thicker, yet still positively buoyant plates. We use lithospheric thickness constraints to predict PBD may be most likely to initiate near the Dali‐Diana Chasmata system.

Floodplains are critical terrestrial-aquatic interfaces that act as hotspots of organic carbon (OC) cycling, regulating ecosystem carbon storage as well as export to riverine systems. Within floodplain sediments, regular flooding and textural gradients interact to create dynamic redox conditions. While anaerobic protection of OC upon burial is a well-recognized carbon storage mechanism in redox-active floodplain sediments, the impact of protective mineral-organic associations is relatively unknown. Here we determined the quantitative importance and chemical composition of mineral-organic associations along well-defined redox gradients emerging from textural variations and depth within meander sediments of the subalpine East River watershed (Gothic, CO). We characterized mineral-organic associations using a combination of sequential extractions, physical fractionation, and high-resolution mass spectrometry. Across the meander, we found that mineral-associated OC constitutes a significant fraction of total OC, and that extractable iron (Fe) and aluminum (Al) phases as well as high-density isolates were strongly correlated with total OC content, suggesting that mineral-organic associations are quantitatively important for floodplain sediment OC protection. Our mass spectrometry results showed OC associated with increasingly ordered Fe and Al phases are relatively enriched in low-molecular weight, oxidized, aromatic compounds. Surprisingly, however, total OC content showed weak or no correlation with indicators of anaerobic protection, such as relatively bioavailable OC pools (water-extractable and particulate OC) or the molecular weight and oxidation state of OC. Overall, this work highlights that protection of OC bound to reactive mineral phases─in addition to anaerobic protection─can play a quantitatively important role in controlling soil carbon storage in redox-active floodplain sediments.

Near-surface seismic structure, particularly the shear wave velocity (Vs), can strongly affect local site response, and should be accurately estimated for ground motion prediction during seismic hazard assessment. The Imperial Valley (California), occupying the southern end of the Salton Trough, is a seismically active basin with thick surficial lacustrine sedimentary deposits. In this study, we utilize ambient noise records and local earthquake events for high-resolution near-surface characterization and site effect estimation with an unlit fiber-optic telecommunication infrastructure (dark fiber) in Imperial Valley by using the distributed acoustic sensing (DAS) technique. We apply ambient noise interferometry to retrieve coherent surface waves from DAS records, and evaluate performances of three different surface wave methods on DAS ambient noise dispersion imaging. We develop a quality control workflow to improve the dispersion measurement of noisy portions of the DAS data set by using a data selection strategy. Using the joint inversion of both the fundamental mode and higher overtones of Rayleigh waves, a high resolution two-dimensional (2D) Vs structure down to 70 m depth is obtained. We successfully achieve an improved Vs30 (the time-averaged shear-wave velocity in the top 30 m) model with higher spatial-resolution and reliability compared to the existing community model for the area. We also explore the potential for utilizing DAS earthquake events for site amplification estimation. The preliminary results reveal a clear anti-correlation between the approximated site response and the Vs30 profile. Our results indicate the potential utility of DAS deployed on dark fiber for near-surface characterization in appropriate contexts.

Salt offers an optimal medium for the permanent isolation of heat-producing radioactive waste due to its impermeability, high thermal conductivity, and ability to close fractures through creep. A thorough understanding of the thermal-hydrological-mechanical (THM) processes, encompassing brine migration, is fundamental for secure radioactive waste disposal within salt formations. At the Waste Isolation Pilot Plant (WIPP), we conducted joint in situ geophysical monitoring experiments during active heating to investigate brine migration near excavations. This experiment incorporated electrical resistivity tomography (ERT) alongside high-resolution fiber-optic-based distributed temperature sensing within a controlled heating experiment. Additionally, discrete element model (DEM) based numerical simulations were conducted to simulate THM processes during heating, providing a more mechanistic understanding of the coupled processes leading to the observed changes in geophysical measurements. During heating, resistivity shifts near the heater were reasonably explained by temperature effects. However, in more distant, cooler regions, the resistivity decrease exceeded predictions based solely on temperature. DEM simulations highlighted brine migration, propelled by pore pressure gradients, as the likely primary factor contributing to the additional resistivity decline beyond temperature effects. The comparison between the predicted ERT responses and observations was much improved when considering the effects of brine migration based on the DEM simulations. These geophysical and simulation findings shed light on brine migration in response to salt heating, enhancing our understanding of the coupled THM processes in salt for safe radioactive waste disposal.

In shallow subduction zones, fluid behavior impacts various geodynamic processes capable of regulating slip behaviors and forming mud volcanoes. However, evidence of structures that control the fluid transfer within an overriding plate is limited and the physical properties at the source faults of slow earthquakes are poorly understood. Here we present high-resolution seismic velocity models and reflection images of the Hyuga-nada area, Japan, where the Kyushu-Palau ridge subducts. We image distinct kilometer-wide columns in the upper plate with reduced velocities that extend vertically from the seafloor down to 10-13 km depth. We interpret the low-velocity columns as damaged zones caused by seamount subduction and suggest that they serve as conduits, facilitating vertical fluid migration from the plate boundary. The lateral variation in upper-plate velocity and seismic reflectivity along the plate boundary correlates with the distribution of slow earthquakes, indicating that the upper-plate drainage system controls the complex pattern of seismic slip at subduction faults.

Abstract: On 4 May 2022 the InSight seismometer SEIS‐VBB recorded the largest marsquake ever observed, S1222a, with an initial magnitude estimate of 4.6. Understanding the depth and source properties of this event has important implications for the nature of tectonic activity on Mars. Located ∼37° to the southeast of InSight, S1222a is one of the few non‐impact marsquakes that exhibits prominent surface waves. We use waveform modeling of body waves (P and S) and surface waves (Rayleigh and Love) to constrain the focal mechanism, assuming a double‐couple source, and find that S1222a likely resulted from reverse faulting in the crust (source depth near 22 km). We estimate the scalar moment to be 2.5 × 1015–3.5 × 1015 Nm (magnitude MW 4.2–4.3). Our results suggest active compressional tectonics near the dichotomy boundary on Mars, likely due to thermal contraction from planetary cooling.

Abstract. Marine diazotrophs convert dinitrogen (N2) gas intobioavailable nitrogen (N), supporting life in the global ocean. In 2012, thefirst version of the global oceanic diazotroph database (version 1) waspublished. Here, we present an updated version of the database (version 2),significantly increasing the number of in situ diazotrophic measurements from13 565 to 55 286. Data points for N2 fixation rates, diazotrophic cellabundance, and nifH gene copy abundance have increased by 184 %, 86 %, and809 %, respectively. Version 2 includes two new data sheets for the nifH genecopy abundance of non-cyanobacterial diazotrophs and cell-specific N2fixation rates. The measurements of N2 fixation rates approximatelyfollow a log-normal distribution in both version 1 and version 2. However,version 2 considerably extends both the left and right tails of thedistribution. Consequently, when estimating global oceanic N2 fixationrates using the geometric means of different ocean basins, version 1 andversion 2 yield similar rates (43–57 versus 45–63 Tg N yr−1; rangesbased on one geometric standard error). In contrast, when using arithmeticmeans, version 2 suggests a significantly higher rate of 223±30 Tg N yr−1 (mean ± standard error; same hereafter) compared to version 1(74±7 Tg N yr−1). Specifically, substantial rate increases areestimated for the South Pacific Ocean (88±23 versus 20±2 Tg N yr−1), primarily driven by measurements in the southwestern subtropics,and for the North Atlantic Ocean (40±9 versus 10±2 Tg N yr−1). Moreover, version 2 estimates the N2 fixation rate in theIndian Ocean to be 35±14 Tg N yr−1, which could not be estimatedusing version 1 due to limited data availability. Furthermore, a comparisonof N2 fixation rates obtained through different measurement methods atthe same months, locations, and depths reveals that the conventional15N2 bubble method yields lower rates in 69 % cases compared tothe new 15N2 dissolution method. This updated version of thedatabase can facilitate future studies in marine ecology andbiogeochemistry. The database is stored at the Figshare repository(https://doi.org/10.6084/m9.figshare.21677687; Shao etal., 2022).

Abstract. Radiative transfer (RT) simulations have long been usedto study the relationships between the inherent optical properties (IOPs) ofseawater and light fields within and leaving the ocean, from which oceanapparent optical properties (AOPs) can be calculated. For example, inversemodels used to estimate IOPs from ocean color radiometric measurements have beendeveloped and validated using the results of RT simulations. Here we describe thedevelopment of a new synthetic optical database based on hyperspectral RTsimulations across the spectral range of near-ultraviolet tonear-infrared performed with the HydroLight radiative transfer code. The keycomponent of this development is the generation of a synthetic dataset ofseawater IOPs that serves as input to RT simulations. Compared to similardevelopments of optical databases in the past, the present dataset of IOPsis characterized by the probability distributions of IOPs that are consistentwith global distributions representative of vast areas of open-ocean pelagicenvironments and coastal regions, covering a broad range of optical watertypes. The generation of synthetic data of IOPs associated withparticulate and dissolved constituents of seawater was driven largely by anextensive set of field measurements of the phytoplankton absorptioncoefficient collected in diverse oceanic environments. Overall, thesynthetic IOP dataset consists of 3320 combinations of IOPs. Additionally,the pure seawater IOPs were assumed following recent recommendations. The RTsimulations were performed using 3320 combinations of input IOPs, assumingvertical homogeneity within an infinitely deep ocean. These input IOPs wereused in three simulation scenarios associated with assumptions aboutinelastic radiative processes in the water column (not considered inprevious synthetically generated optical databases) and three simulationscenarios associated with the sun zenith angle. Specifically, the simulationswere made assuming no inelastic processes, the presence of Raman scatteringby water molecules, and the presence of both Raman scattering andfluorescence of chlorophyll a pigment. Fluorescence of colored dissolvedorganic matter was omitted from all simulations. For each of these threesimulation scenarios, the simulations were made for three sun zenith anglesof 0, 30, and 60∘ assuming clear skies, standardatmosphere, and a wind speed of 5 m s−1. Thus, overall 29 880 RTsimulations were performed. The output results of these simulations includeradiance distributions, plane and scalar irradiances, and a whole setof AOPs, including remote-sensing reflectance, vertical diffuseattenuation coefficients, and mean cosines, where all optical variables arereported in the spectral range of 350 to 750 nm at 5 nm intervals fordifferent depths between the sea surface and 50 m. The consistency of thisnew synthetic database has been assessed through comparisons with in situdata and previously developed empirical relationships involving IOPs andAOPs. The database is available at the Dryad open-access repository of researchdata (https://doi.org/10.6076/D1630T, Loisel et al., 2023).

We have investigated the hydrothermal alteration of polished wafers of tuff reacted with dilute groundwater at 90 °C, 150 °C and 250 °C for time periods ranging from 2 months to nearly 1 year. The polished rock wafer provided a convenient surface upon which to grow secondary minerals. Reaction product minerals were identified and analyzed at the end of each experiment and, along with the evolving fluid chemistry, were compared to computational results from corresponding reaction progress models. At 250 °C after a few months the run products in the experiment were dominantly the mordenite group zeolite minerals: dachiardite (a Ca-rich variety) and mordenite, itself. At 150 °C after a few months of reaction only minor amounts of clay were produced, but after 1 year of reaction at this temperature both mordenite group zeolites were again present. At this lower temperature the total amount of run products was much smaller. At 90 °C no run products could be seen at all, even after 1 year of reaction. The reaction progress modeling results for reaction products were in good relative agreement with the experimental results. The higher the temperature, and the greater the extent of reaction, the better the fluid phase modeling results agreed with the actual experimental results. At 250 °C the agreement was good for nearly all elements. At 150 °C agreement for pH, SiO2, Na and K were good, but less good for Al, Mg and Ca, especially after short reaction times. At 90 °C agreement for pH, SiO2 and Na was reasonable, but not as good for the other elements, and all modeling results for short reaction times did not match experimental results as well as the longer time results. This study demonstrates that reaction progress modeling provides a powerful tool for predicting hydrothermal rock-water interactions, with results expected to improve, as more and better quality thermodynamic and kinetic data become available and as process-oriented simulators incorporate better and more comprehensive sub-models for mineral dissolution and growth.

Organo-mineral and organo-metal associations play an important role in the retention and accumulation of soil organic carbon (SOC). Recent studies have demonstrated a positive correlation between calcium (Ca) and SOC content in a range of soil types. However, most of these studies have focused on soils that contain calcium carbonate (pH > 6). To assess the importance of Ca-SOC associations in lower pH soils, we investigated their physical and chemical interaction in the grassland soils of Point Reyes National Seashore (CA, USA) at a range of spatial scales. Multivariate analyses of our bulk soil characterisation dataset showed a strong correlation between exchangeable Ca (CaExch; 5-8.3 c.molc kg-1) and SOC (0.6-4%) content. Additionally, linear combination fitting (LCF) of bulk Ca K-edge X-ray absorption near-edge structure (XANES) spectra revealed that Ca was predominantly associated with organic carbon across all samples. Scanning transmission X-ray microscopy near-edge X-ray absorption fine structure spectroscopy (STXM C/Ca NEXAFS) showed that Ca had a strong spatial correlation with C at the microscale. The STXM C NEXAFS K-edge spectra indicated that SOC had a higher abundance of aromatic/olefinic and phenolic C functional groups when associated with Ca, relative to C associated with Fe. In regions of high Ca-C association, the STXM C NEXAFS spectra were similar to the spectrum from lignin, with moderate changes in peak intensities and positions that are consistent with oxidative C transformation. Through this association, Ca thus seems to be preferentially associated with plant-like organic matter that has undergone some oxidative transformation, at depth in acidic grassland soils of California. Our study highlights the importance of Ca-SOC complexation in acidic grassland soils and provides a conceptual model of its contribution to SOC preservation, a research area that has previously been unexplored.Supplementary informationThe online version contains supplementary material available at 10.1007/s10533-023-01059-2.

A hundred years after the discovery of the Merensky Reef in 1924, it is appropriate to present the new mineral andrieslombaardite in honour of Andries Frederik Lombaard who was instrumental in its discovery. Andrieslombaardite, RhSbS, was first described as an unknown mineral from placer deposits associated with the Tulameen Alaskan-Uralian type complex, British Colombia, Canada (Raicevic and Cabri, 1976) but has since been reported from several other deposits including the platiniferous Driekop, Mooihoek, and Onverwacht pipes in the eastern Bushveld Complex, South Africa. The mineral and the name were approved by the Commission on New Minerals Nomenclature and Classification (CNMNC) of the International Mineralogical Association (IMA no. 2022-076) based on data in the co-type samples from Onverwacht and a co-type sample from the Yubdo stream, Birbir River, Ethiopia. Andrieslombaardite in the Onverwacht sample is a single 8 x 20 μm grain attached to laurite in a matrix of altered silicate and Fe-oxyhydroxide minerals. In the Yubdo samples, there are many grains of pale brownish gray andrieslombaardite up to 25 x 55 μm in size, included in Pt-Fe alloys, some associated with erlichmanite, and others attached to bornite and chalcopyrite. The reflectance values (R%) measured in air and in oil at the COM wavelengths are 48.3 and 33.0 (470 nm), 49.3 and 34.0 (546 nm), 51.0 and 35.9 (589 nm), and 51.8 and 36.7 (650 nm). The colour values x, y, Y, λd, and Pe in air are 0.317, 0.322, 50.3, 580, and 3.2, and in oil are 0.319, 0.324, 35.6, 579, and 4.5. The composition of andrieslombaardite is ideally RhSbS, but it contains variable amounts of Fe, Pt, Pd, and Ir that may substitute for Rh. The mineral is cubic with unit-cell dimensions of a = 6.0278(4) Å, V = 219.01(6) Å3 and Z = 4. It was synthesised at 400 and 550°C using stoichiometric elemental amounts. It is a member of the cobaltite group. The mineralisation of the intrusive dunite pipes was probably introduced at high temperatures, under magmatic conditions. The primary assemblages were to a certain degree overprinted and redistributed by low-temperature hydrothermal fluids. The Pt-Fe alloys from Yubdo containing PGM inclusions such as andrieslombaardite in the Yubdo-Alaskan-type complex were formed at some post-magmatic stage owing to PGE remobilisation during hydrothermal or metamorphic episodes.

Magnetotelluric data were used to study the lithosphere structure of the Southern Oklahoma Aulacogen (SOA). Inversion of the data revealed two low resistivity anomalies beneath the SOA. The first is located in the depth range 0–90 km in the crust and upper lithospheric mantle. The second extends from a depth 100 km to the base of the lithospheric mantle and extends away from the SOA to the ends of the profile. The cause of low resistivity anomalies is discussed in relation to the tectonic evolution of the region and recent laboratory experiments on rock conductivity. The first anomaly is attributed to the combination of (a) water present in mantle minerals and (b) the formation of hydrous mineral phases by interactions between a plume and the lithosphere during rifting. Grain size reduction and fabric alignment from deformation during the Ancestral Rocky Mountain (ARM) orogeny may have also contributed to the low resistivity. This enrichment phase may have mechanically weakened the lithosphere and allowed deformation to occur during the ARM orogeny. The low resistivity of the deeper anomaly is attributed to a fluorine-enriched phlogopite layer that is also coincident with an observed seismic mid-lithosphere discontinuity (MLD). A lithosphere keel of mantle minerals enriched in water underlies this layer and may have formed by accretion of the plume head to the lower lithosphere after rifting, which also rethickened the lithosphere to its present-day depths. The MLD may then reflect a melt layer along a paleo lithosphere-asthenosphere boundary entombed during the accretion.

Consideration is given to results of geochemical analysis of organic matter and oils of the Proterozoic (the RF-V complex) and the Paleozoic (the pay intervals D2, D3, C1-2) of the eastern part of the Volga-Urals petroleum basin. The obtained data is corroborated by results of 2D basin modeling along four regional profiles two of which are situated in the Kama and two in the Belaya parts of the Kama-Belaya aulacogen. An update is given to earlier data on degree of catagenetic alteration of oil/gas source rocks of the Riphean-Vendian play, maps of catagenesis are constructed. New evidence is provided concerning presence of Precambrian oils in the Paleozoic plays. The oils under investigation are mixed – those formed from generation products of the Precambrian (Riphean, Vendian) and Paleozoic (Devonian and Early Carboniferous) source rock intervals. The results of modeling have shown that the principal source rock intervals in the RF-V play of the Kama part of the Kama-Belaya aulacogen are deposits of the Kaltasy formation of the Lower Riphean and the Vereshchagino formation of the Upper Vendian, while in the Belaya part these are rocks of the Kaltasy, Kabakov, Olkhovo, Priyutovo, Shikhan and Leuza formations of the Riphean and the Staropetrovo formation of the Vendian. It is found that the interval of the main oil and gas window increases in the southeastward direction. In both depressions of the Kama-Belaya aulacogen, a single oil play is distinguished that functions within the stratigraphic interval from the Riphean to the Lower Carboniferous. As the principal petroleum source rock intervals within this play, Riphean-Vendian deposits are considered, reservoirs are confined to the Riphean carbonate complex, Upper Vendian and Middle Devonian clastic deposits, while the Upper Devonian – Tournaisian deposits serve as the upper seal.

Abstract The Sukhothai Historical Park, designated as a world heritage site in Thailand, encompasses the remnants of the Sukhothai Kingdom and serves as a valuable locus for geological and geoarchaeological investigations. Situated in the Sukhothai province, the region is characterized by diverse lithologies, including slate, phyllite, and laterite, as well as red bricks (synthetic materials), utilized in the construction of various ancient structures. Petrographic analysis using polarized light microscopy reveals the phyllites as the primary dimension stones, exhibiting foliated and mylonitic textures with small quartz augen. A portable X-ray fluorescence analyzer was employed for geochemical analysis and the analysis of major oxides and trace elements. The resulting data facilitated the classification of protoliths and comparison with rocks from an abandoned quarry near Saritphong Dam in the western part of the historical park. Notably, phyllites utilized in several prominent structures within the park; Wat Saphan Hin, Wat Pa Daeng 2, Wat Thap Sakae, Wat Chetuphon, Wat Sri Chum, and Wat Mangkorn Temples, exhibited similar characteristics to those in the Wat Khao Noi old quarry, as confirmed by Rubidium (Rb) and Strontium (Sr) values. The SiO2/Al2O3 and FeO/K2O ratios were pivotal in identifying the protoliths of the studied phyllites as shales. In summary, the primary dimension stones for Sukhothai Historical Park originated from the western mountain within the park, with laterites sourced from foothill areas. The presence of quartz pebbles in red bricks suggests local sediment utilization, and quartz additions were employed to enhance structural strength. This comprehensive geoarchaeological study sheds light on the geological composition of the Sukhothai Historical Park, providing valuable insights into the selection and utilization of construction materials in this historically significant site.

This study focuses on palaeoenvironmental changes in the Bottomless Lake (Tăul fără fund) Sphagnum peat bog situated near Bǎgǎu in Romania. The central research question was how the lake has changed over time, and how environmental factors and human activities have influenced the changes. By employing previous loss-on-ignition and radiocarbon analyses in addition to new radiocarbon, grain size, magnetic susceptibility and geochemical analyses, a more precise reconstruction of the bog's regeneration and erosion phases was achieved. A multi-proxy analysis of the core sequence provided crucial insights regarding the interconnections between various elements. Notably, plant-derived elements (Na, K) exhibited correlations with organic matter, and carbonate elements (Ca, Mg) with carbonate content; while Fe and magnetic susceptibility displayed changes in relation to inorganic matter content. Remarkably, the findings reflected the global 8200 cal BP and 4200 cal BP events, along with their environmental effects, within the Transylvanian Basin. There was mediaeval lakebed cleaning around 500300 cal BP, during which the deeper of two water layers was contaminated with more recent materials. The shallower water layer is connected with the modern water circulation, which reduces the apparent age of peat samples taken from its immediate vicinity.

Groundwater is utilized as a clean water source including in Pelauw and Kariu Villages. Drilling and excavating are frequent techniques utilized in the construction of wells that serve as sources of groundwater. As a result of the ocean encircling the majority of this area, salinity may infiltrate wells. Consequently, the purpose of this study was to ascertain whether seawater intrusion had occurred in 12 nearby wells. Major ion tests were carried out in the lab, while surveys and measurement fields were carried out for the sampling procedure. Ion Cl, EC, TDS, Simpson ratio, and BEX data are used in the analysis to determine whether seawater intrusion is present. Additionally, the Piper diagram is used to categorize different types of water based on the outcomes of the main ion test. The findings indicated that Cl-, EC, and TDS levels have increased at a number of the sampling sites. At point A09, there is an indication of seawater intrusion based on the BEX values, which shows a negative number. The majority of the well water, as determined by a water classification analysis using the Piper diagram, is of the calcium carbonate type. Meanwhile, the remaining portion is separated into the calcium sulfate and sodium bicarbonate types.

There were a variety of high content elements associated with the early Cambrian stone coal in northeastern Hunan province, and the attribute characteristics were distinct. In order to find out the sedimentary sources of stone coal in this area, the contents of major elements and trace elements in 12 stone coal samples were determined by X-ray fluorescence spectrometer (XRF) and inductively coupled plasma mass spectrometer (ICP–MS). Based on the combination of major elements, content characteristics of trace elements, distribution characteristics of rare earth elements and geochemical parameters of related elements, the source regions of the early Cambrian stone coal deposits in northeast Hunan province were discussed. The results showed that the early Cambrian stone coal in northeast Hunan province was mainly composed of inorganic minerals, and the content of SiO2 was the highest in the stone coal. The relationships between SiO2 and other major elements (and other major elements) were not obvious, and the quartz mineral morphology was characterized by terrigenous input. The trace elements (V, As, Sr, Mo, Cd, Sb, Ba, Bi, U) in stone coal were obviously enriched. The distribution characteristics of rare earth elements and the relationship between Nb/Y–Zr/TiO2 indicated that stone coal was influenced by neutral rock. LaN/YbN indicated that the deposition rate of stone coal deposits decreases from southeast to northwest. Means, the source comes from the eastern and southern directions; The w(SiO2)/w(Al2O3), w(Al2O3)/w(Al2O3+Fe2O3), w(Al)/w(Al+Fe+Mn) and K2O/Na2O–SiO2 structural discrimination models showed that the early Cambrian stone coal was deposited in the continental margin area, mainly receiving continental sources. Based on the comparison with the contents of rare earth elements, Rb, Nb and Pb in the middle-acid rocks of Shangshu Group distributed in the southeast direction of the study area, and the contents and combination characteristics of major elements in the magmatic rocks of Shuangxiwu Group, and combined with the evolution history of Jiangnan Orogenic belt, the middle-acid rock belt developed in the southeastern margin of Jiangnan orogenic belt was considered to be the source region of the early Cambrian stone coal deposits in northeast Hunan province. It was also one of the main controlling factors for the enrichment of trace elements in stone coal.

Seawater intrusion is a global environmental geological issue that poses a serious threat to the water supply security and ecological environment of coastal cities. Microorganisms exhibit a high sensitivity to environmental changes, and in recent years, numerous scholars have turned their attention to the response characteristics of microorganisms to seawater intrusion, offering new perspectives and methodologies for research in this field. To completely understand the research progress in this field, this study, based on the Web of Science core database, employed bibliometric visualization analysis methods to analyze the current status, hotspots, and trends of research on microbial response characteristics to seawater intrusion. The results indicate that significant developments in this emerging research area have mainly occurred after 2011, with a consistent increase in publication volume and citation counts. Chinese scholars actively engage in the research of microbial responses to seawater intrusion, ranking second in terms of both publication output and h-index, with a significant academic impact. Keyword cluster analysis reveals that popular research topics in this field encompass the response of groundwater microbial communities to seawater intrusion, investigations into soil microbial communities’ response to seawater intrusion, and the geochemical cycling of elements in conjunction with microbial processes. The study indicates that the succession of microbial communities in brackish-saline water transition zones is jointly influenced by factors such as salinity, dissolved oxygen, temperature, organic carbon, and pH. The primary controlling factors vary with hydrogeological conditions. The intrusion of seawater impacts microbial-mediated processes involved in the cycling of carbon, nitrogen, sulfur, iron, and other substances. The identification of typical marine bacteria and halophilic archaea found in aquifers holds significant indicative value concerning seawater intrusion. This serves as a potent complement to traditional investigative methods for seawater intrusion, offering substantial potential and advantages in distinguishing paleoseawater intrusion and seawater intrusion.

The Moon's mare volcanism predominantly occurs within the Procellarum KREEP Terrane (PKT), which is widely thought to be associated with KREEP components within the lunar interior. The Chang'e-5 (CE-5) mission sampled a young (2 Ga) mare basalt Em4/P58 unit of northern Oceanus Procellarum. The geochemistry of the CE-5 mare basalt enables assessment of mantle source compositions which are essential to understand the thermo-chemical mechanism for prolonged volcanism during secular cooling of the Moon. Geochemical compositions of the CE-5 bulk soil, breccias, and basalt clasts from various depths within the drill core consistently display high concentrations of incompatible trace elements (ITE: ∼ 0.3 × high-K KREEP; ∼ 5 μg/g Th) with KREEP-like inter-element ratios, for example for La/Sm, Nb/Ta, and Zr/Y. Exotic impact ejecta, extensive magma differentiation (<70 % fractional crystallization) and significant assimilation of KREEP materials during magma transit and eruption cannot account for the ITE contents and ratios or radiogenic isotope compositions (e.g., εNd initial of + 8 to + 9 and εHf initial of + 40 to + 46) of the CE-5 basalts; instead, partial melting of their mantle source played a dominant role. The Chang'e-5 basalt is a chemically evolved low-Ti mare basalt (Mg# of ∼ 34) with enriched KREEP-like ITE compositions but high long-term time-integrated Sm/Nd and Lu/Hf ratios, which represent a hitherto unsampled type of mare basalt. It formed by melting of an augite-rich mantle source (late-stage magma ocean cumulates containing > 30–60 % augite, and little or no ilmenite), with a small amount of late-stage interstitial melt that resembles KREEP (∼1–1.5 modal %, equivalent to 0.2–0.3 μg/g Th in the mantle source). The voluminous mare basalts making up the Em4/P58 unit (>1500 km3) provide compelling evidence for large-scale, ITE enriched young mare magmatism within Oceanus Procellarum. In combination with remote sensing data and with the unique Th-rich Apollo 12 basalt fragment 12032,366–18 (impact ejecta likely from Oceanus Procellarum), this implies that significant portions of the FeO- and Th-rich mare regions of the western PKT may also have formed in a similar way. [ABSTRACT FROM AUTHOR]

Earth's first continental crust is formed by Archaean and mainly consisted of tonalite–trondhjemite–granodiorite with a small amount of diorites (DTTGs), which has an essential role in probing early crust–mantle dynamic regime and in understanding the formation mechanism of continental crust. Here, we present zircon U‒Pb dating and Lu‒Hf isotopes, whole-rock geochemistry, and petrography on DTTGs rocks in the Dunhuang Block. Three episodes of DTTGs were emplaced circa 2.67 Ga, 2.60 Ga, and 2.50 Ga. The circa 2.67 Ga TTGs exhibit high SiO2 contents (68.14–71.70 wt%), low MgO contents (0.65–1.31 wt%), and high ratios of (La/Yb)N (146 on average), with their enriched Nd-Hf isotopes [ƐHf (t) = -5.48–3.19 and ƐNd (t) = -5.77–0.53], indicating origination from partial melting of amphibolites at thickened lower crust. In contrast, the circa 2.60 Ga transitional TTGs exhibit relatively high MgO contents (2.80–3.39 wt%), flat REE (Rare earth element) patterns with moderate ratios of (La/Yb)N (20.49 on average), and dispersed Nd-Hf isotopes [ƐHf (t) = -5.48–3.19 and ƐNd (t)= −3.99–3.08]. Accordingly, circa 2.60 Ga transitional TTGs melts were produced by partial melting of the shallower crust induced by mantle-derived magma upwelling. The circa 2.50 Ga diorites exhibit low SiO2 (55.72–59.11 wt%) but high MgO (3.51–4.52 wt%) contents with positive Nd-Hf isotopes [ƐHf (t) = -0.16–4.17 and ƐNd (t) = 2.00–4.45], suggesting that they originated from partial melting of mantle wedges metasomatized by fluid from subduction slabs. Combined with the detailed petrogenetic studies and crustal thickness variation, we conclude that the complex crust–mantle interaction may be an essential reason for the Neoarchaean diversity of DTTGs from the Dunhuang Block, which experienced prolonged arc accretion before Neoarchaean, followed by delamination between 2.67 and 2.60 Ga and subsequently transitioned to subduction. [ABSTRACT FROM AUTHOR]

The evolution of the Gondwana along the flank of the West African Craton was complex and is far from understood. Subduction-related activity along this margin spanned between c. 750 and 500 Ma. Sections close to African cratons record the earliest stages, while Autochthonous and Allochthonous domains of the Variscan Belt preserve the latest stages of the arc system, essentially between c. 540 and 500 Ma. The geochemistry of the Ediacaran-early Cambrian siliciclastic series deposited along this Cadomian active margin preserves the evolutionary history of their sources, which are related to activity in the arc and nearby continental areas. In this sense, the SW Iberian Massif (Ossa-Morena Complex) preserves a section of this Ediacaran-early Cambrian peri-Gondwanan arc. Its evolution can be tracked through the characterization of the subduction-related magmatism (including the Mérida Massif) and coeval metasedimentary record (Serie Negra Group and Malcocinado Formation) during a time interval spanning almost 100 m.y., from pre-602 Ma to at least c. 534 Ma. This study reveals that arc magmatism is closely linked with synorogenic deposition in a complex way so far unexplored. Arc recycling is revealed by the isotopic equivalence of synorogenic strata to the first magmatic event (pre-602 Ma), and by geochronological data of the arc-building pulses. The earliest magmatic pulses (c. 602–550 Ma) are characterized by significant crustal input, likely favoured by subduction erosion. Subsequently, magmatism evolved towards larger mantle involvement (c. 540–534 Ma), likely associated with progressive variation in the slab angle. These slab-mantle-upper plate interactions generated changes in the arc dynamics leading to an extensional setting with alkaline magmatism during the Cambrian. This review proposes a model of petrogenetic and geodynamic arc evolution between the Ediacaran and the Early Cambrian. The gathered data could improve the accuracy of future palaeogeographic reconstructions for the northern margin of Gondwana. [ABSTRACT FROM AUTHOR]

The paper presents new geological, geochronological, geochemical and Nd-Sr isotopic data on the Meso- Neoproterozoic dolerites of the Siberian Craton. New U-Pb baddeleyite and apatite ages of a E-W-trending dyke and two sills from southeastern Siberia are 982 ± 11, 977 ± 7, 970 ± 31 and 972 ± 60 Ma, respectively, extending the area of distribution of the event by more than 100 km to the north. The Sette-Daban intrusions are subalkalic mostly low-Ti dolerites, although high-Ti dolerites have been locally documented as well. Trace element abundances in dolerites vary from typical to E-MORB to OIB with arc-like signatures represented by high Th/Yb and low TiO2/Yb ratios. All dolerite samples display moderately positive εNd(t) values varying from +3.3 to +7.7 and indicating the magmas were derived from a depleted mantle source. E-MORB and OIB intrusions are attributed to the different degree of interaction of magma between the depleted asthenospheric mantle and regions within the sub-continental lithospheric mantle (SCLM) that were metasomatically enriched during earlier subduction events. Available data on Sette-Daban event distribution, composition and duration satisfy the characteristics of a typical Large Igneous Province (LIP). Similar age 1000–950 Ma mafic magmatism is also recognized in the Baltic and Amazonian cratons and can be potentially correlated with the Sette-Daban event. [ABSTRACT FROM AUTHOR]

Iron oxide-copper-gold (IOCG) deposits are a vital source of copper and critical elements for emerging clean technologies. Andean-type IOCG deposits form in continental arcs undergoing extension, and they have a temporal relationship with magmatism although they do not exhibit a close spatial relation with the causative intrusions. The processes required to form IOCG deposits and their potential connections to iron oxide–apatite (IOA)-type mineralization remain poorly constrained, as well as the characteristics of magmatism linked to both deposit types. Here we combine zircon U–Pb geochronology with zircon trace element geochemistry of intrusive rocks associated with the Candelaria deposit, one of the world's largest IOCG deposits, to unravel distinctive signatures diagnostic of magmatic fertility. Our results reveal a marked transition in the geochemistry of intrusions in the Candelaria district, characterized by changes in the redox state, water content and temperature of magmas over time. The oldest magmatic stage (~ 128–125 Ma), prior to the formation of the Candelaria deposit, was characterized by zircon Eu/Eu* ratios of 0.20–0.42, and redox conditions of ΔFMQ − 0.4 to + 1.0. The earliest magmatic stage related to the formation of Fe-rich mineralization at Candelaria (118–115 Ma) exhibits low zircon Eu/Eu* ratios (0.09–0.18), low oxygen fugacity values (ΔFMQ ~− 1.8 to + 0.2) and relatively high crystallization temperatures. In contrast, the youngest stage at ~ 111–108 Ma shows higher zircon Eu/Eu* (~ 0.37–0.69), higher oxygen fugacity values (ΔFMQ ~ + 0.4 to + 1.3) and a decrease in crystallization temperatures, conditions that are favorable for the transport and precipitation of sulfur and chalcophile elements. We conclude that Candelaria was formed through two distinct ore-forming stages: the first associated with a reduced, high temperature, water-poor magma developed under a low tectonic stress, followed by a more oxidized, water-rich, and low temperature magmatic event related to a compressional regime. The first event led to Fe-rich and S-poor IOA-type mineralization, while the second event with geochemical signatures similar to those of porphyry copper systems, generated the Cu- and S-rich mineralization. This late stage overprinted preexisting IOA mineralization resulting in the formation of the giant Candelaria IOCG deposit. [ABSTRACT FROM AUTHOR]

Primary studies of the concentrations of rare elements in the sediments of two lakes on King George Island (Kitezh and Glubokoe) showed that their geochemistry reflects the geological features of the area. Compared to the composition of the upper part of the Earth's crust, the studied sediments are enriched in Cu, Cd, V, Tl, Mn, Ti, and P. Similar patterns have been identified in the geochemistry of volcanic and sedimentary rocks of the Fildes Peninsula. Trends in REE changes generally follow their behavior in rocks, but the overall REE concentration in sediments of lakes is higher, which may be due to the presence of organic matter accumulating in sediments of water bodies. Unlike the aquatic environment, the chemical composition of sediments does not reflect the significant influence of the activities of polar stations. However, small increases in Pb and Sb concentrations in the upper sediments suggest the influence of long–range atmospheric transport of the contaminants. [ABSTRACT FROM AUTHOR]