Preprints
Filtering by Subject: Geochemistry
Copper availability governs nitrous oxide accumulation in wetland soils and stream sediments
Published: 2021-12-15
Subjects: Biogeochemistry, Civil and Environmental Engineering, Earth Sciences, Engineering, Environmental Engineering, Geochemistry, Life Sciences
Denitrification is microbially-mediated through enzymes containing metal cofactors. Laboratory studies of pure cultures have highlighted that the availability of Cu, required for the multicopper enzyme nitrous oxide reductase, can limit N2O reduction. However, in natural aquatic systems, such as wetlands and hyporheic zones in stream beds, the role of Cu in controlling denitrification remains [...]
Thermochemical structure and evolution of cratonic lithosphere in central and southern Africa
Published: 2021-12-10
Subjects: Earth Sciences, Geochemistry, Geophysics and Seismology, Mineral Physics, Physical Sciences and Mathematics, Tectonics and Structure
The thermochemical structure of the subcontinental mantle holds information on its origin and evolution that can inform energy and mineral exploration strategies, natural hazard mitigation and evolutionary models of the Earth. However, imaging the fine-scale thermochemical structure of continental lithosphere remains a major challenge. Here we combine multiple land and satellite datasets via [...]
Elevated Post K-Pg Export Productivity in the Gulf of Mexico and Caribbean
Published: 2021-12-10
Subjects: Earth Sciences, Geochemistry, Paleobiology, Paleontology, Physical Sciences and Mathematics
The global heterogeneity in export productivity after the Cretaceous-Paleogene (K-Pg) mass extinction is well documented, with some sites showing no change on geologic timescales, some demonstrating sustained decline, and a few showing a somewhat surprising increase. However, observational data come from sites so widespread that a key outstanding question is the geographic scale of changes in [...]
Multi-proxy assessment of surface sediments using APPI-P FTICR-MS reveals a complex biogeochemical record along a salinity gradient in the Pearl River estuary and coastal South China Sea
Published: 2021-12-10
Subjects: Analytical Chemistry, Biogeochemistry, Chemistry, Earth Sciences, Environmental Chemistry, Environmental Monitoring, Environmental Sciences, Geochemistry, Physical Sciences and Mathematics
The Pearl River drains the second largest watershed in China, funnelling large amounts of freshwater and organic matter into the northern part of the South China Sea through an estuary characterized by pronounced biogeochemical gradients. In this study we analyzed organic extracts of surface sediments collected along land-sea transect that captures a transition from freshwater environment at the [...]
Catchment vegetation and erosion controls soil carbon cycling in south-eastern Australia during the last two Glacial-Interglacial cycles
Published: 2021-12-10
Subjects: Earth Sciences, Geochemistry, Geomorphology, Sedimentology
Shallow depth, substantial change: fluid-metasomatism causes major compositional modifications of subducted volcanics (Mariana forearc)
Published: 2021-12-02
Subjects: Earth Sciences, Geochemistry, Geology
Mass transfer at shallow subduction levels and its ramifications for deeper processes remain incompletely constrained. New insights are provided by ocean island basalt (OIB) clasts from the Mariana forearc that experienced subduction to up to ~25–30 km depth and up to blueschist-facies metamorphism; thereafter, the clasts were recycled to the forearc seafloor via serpentinite mud volcanism. We [...]
Estuarine-deltaic controls on coastal carbon burial in the western Ganges-Brahmaputra delta over the last 5,000 years
Published: 2021-11-26
Subjects: Applied Statistics, Biogeochemistry, Earth Sciences, Environmental Sciences, Geochemistry, Geology, Geomorphology, Other Earth Sciences, Other Environmental Sciences, Other Statistics and Probability, Physical Sciences and Mathematics, Sedimentology, Statistical Methodology, Statistical Models, Statistics and Probability, Water Resource Management
The Ganges–Brahmaputra fluvial system drains the Himalayas and is one of the largest sources of terrestrial biosphere carbon to the ocean. It represents a major continental reservoir of CO2 associated with c. 1–2 billion tons of sediment transported each year. Shallow coastal environments receive substantial inputs of terrestrial carbon (900 Tg C yr−1), with allochthonous carbon capture on [...]
Geochemical variability as an indicator for large volume eruptions in volcanic arcs
Published: 2021-11-17
Subjects: Earth Sciences, Geochemistry, Geology, Volcanology
Caldera-forming eruptions have the potential to impact global climate and induce drastic socioeconomic change. However, the criteria to identify volcanoes capable of producing large magnitude eruptions in the future are not well constrained. Here we compile and analyse data, revealing that volcanoes which have produced catastrophic caldera-forming eruptions in the past, typically show larger [...]
Plagioclase archives of depleted melts in the oceanic crust
Published: 2021-11-15
Subjects: Geochemistry, Geology
Mid-ocean ridge and ocean island basalts provide vital but incomplete insights into mantle chemistry. For example, high-anorthite plagioclase is generally too refractory and incompatible-element depleted to have crystallized from the melts that carry it to the surface. Moreover, erupted basalts rarely preserve the extreme isotopic and incompatible-element depletions found in some primitive melt [...]
Rare allanite in granulitised eclogites constrains timing of eclogite to granulite facies transition in the Bhutan Himalaya
Published: 2021-11-15
Subjects: Earth Sciences, Geochemistry, Geology, Physical Sciences and Mathematics, Tectonics and Structure
During continental collision, crustal rocks are buried, deformed, transformed and exhumed. The rates, timescales and tectonic implications of these processes are determined by linking geochemical, geochronological and microstructural data from metamorphic rock-forming and accessory minerals. Exposures of lower orogenic crust provide important insights into orogenic evolution, but are rare in [...]
Stable Silicon Isotopes Uncover a Mineralogical Control on the Benthic Silicon Cycle in the Arctic Barents Sea
Published: 2021-11-12
Subjects: Biogeochemistry, Earth Sciences, Geochemistry, Physical Sciences and Mathematics, Soil Science
Biogeochemical cycling of silicon (Si) in the Barents Sea is under considerable pressure from physical and chemical changes, including dramatic warming and sea ice retreat, together with a decline in dissolved silicic acid (DSi) concentrations of Atlantic inflow waters since 1990. Moreover, further expansion of the Atlantic realm (termed ‘Atlantification’) is expected to shift phytoplankton [...]
Open access in geochemistry from preprints to data sharing: past, present and future
Published: 2021-11-08
Subjects: Biogeochemistry, Cosmochemistry, Earth Sciences, Geochemistry, Volcanology
In this short communication, we discuss the latest advances regarding Open Access in the Earth Sciences and geochemistry community from preprints to findable, accessible, interoperable and reusable data following 14f session held at Goldschmidt conference (4-9 July 2021) dedicated to “Open Access in Earth Sciences”.
Reproducibility in subsurface geoscience
Published: 2021-10-27
Subjects: Biogeochemistry, Cosmochemistry, Earth Sciences, Environmental Education, Environmental Health and Protection, Environmental Indicators and Impact Assessment, Environmental Monitoring, Environmental Sciences, Geochemistry, Geology, Geomorphology, Geophysics and Seismology, Glaciology, Hydrology, Mineral Physics, Natural Resource Economics, Natural Resources and Conservation, Natural Resources Management and Policy, Oil, Gas, and Energy, Other Earth Sciences, Other Environmental Sciences, Paleobiology, Paleontology, Sedimentology, Soil Science, Speleology, Stratigraphy, Sustainability, Tectonics and Structure, Volcanology, Water Resource Management
Reproducibility, the extent to which consistent results are obtained when an experiment or study is repeated, sits at the foundation of science. The aim of this process is to produce robust findings and knowledge, with reproducibility being the screening tool to benchmark how well we are implementing the scientific method. However, the re-examination of results from many disciplines has caused [...]
Constraints on the ice composition of carbonaceous chondrites from their magnetic mineralogy
Published: 2021-10-22
Subjects: Earth Sciences, Geochemistry, Physical Sciences and Mathematics, Planetary Sciences
Carbonaceous chondrites experienced varying degrees of aqueous alteration on their parent asteroids, which influenced their mineralogies, textures, and bulk chemical and isotopic compositions. Although this alteration was a crucial event in the history of these meteorites, their various alteration pathways are not well understood. One phase that formed during this alteration was magnetite, and [...]
Improving the reliability of Fe- and S-XANES measurements in silicate glasses: Correcting beam damage and identifying Fe-oxide nanolites in hydrous and anhydrous melt inclusions
Published: 2021-10-19
Subjects: Geochemistry, Geology, Mineral Physics, Physical Sciences and Mathematics, Volcanology
The redox state of silicate melts influences crystallization, element partitioning, and degassing behavior. Synchrotron-based micro-X-ray absorption near edge structure (μXANES) spectroscopy has emerged as a powerful tool for determining redox conditions through the direct measurement of speciation of multivalent elements such as iron and sulfur in silicate glasses. In particular, the high [...]