Preprints

Filtering by Subject: Geochemistry

Explosive activity on Kīlauea’s Lower East Rift Zone fuelled by a volatile-rich, dacitic melt

Penny E Wieser, Marie Edmonds, Cheryl Gansecki, et al.

Published: 2022-01-12
Subjects: Earth Sciences, Geochemistry, Physical Sciences and Mathematics, Volcanology

Magmas with matrix glass compositions ranging from basalt to dacite erupted from a series of 24 fissures in the first two weeks of the 2018 Lower East Rift Zone (LERZ) eruption of Kīlauea Volcano. Eruption styles ranged from low spattering and fountaining to strombolian activity. Major element trajectories in matrix glasses and melt inclusions hosted by olivine, pyroxene and plagioclase are [...]

Insights into Magma Storage Beneath a Frequently Erupting Arc Volcano (Villarrica, Chile) from Unsupervised Machine Learning Analysis of Mineral Compositions

Felix Boschetty, David Ferguson, Joaquín Cortés, et al.

Published: 2022-01-12
Subjects: Geochemistry, Geology, Volcanology

A key method to investigate magma dynamics is the analysis of the crystal cargoes carried by erupted magmas. These cargoes may comprise crystals that crystallize in different parts of the magmatic system (throughout the crust) and/or different times. While an individual eruption likely provides a partial view of the sub-volcanic plumbing system, compiling data from multiple eruptions builds a [...]

The DIC carbon isotope evolutions during CO2 bubbling: implications for ocean acidification laboratory culture

Hongrui Zhang, Ismael Torres-Romero, Pien Anjewierden, et al.

Published: 2022-01-05
Subjects: Biogeochemistry, Earth Sciences, Geochemistry

Ocean acidification increases pCO2 and decreases pH of seawater and its impact on marine organisms has emerged as a key research focus. In addition to directly measured variables such as growth or calcification rate, stable isotopic tracers such as carbon isotopes have also been used to more completely understand the physiological processes contributing to the response of organisms to ocean [...]

Calibrating the temporal and spatial dynamics of the Ediacaran - Cambrian radiation of animals

Fred Toby Bowyer, Andrey Yu Zhuravlev, Rachel Wood, et al.

Published: 2021-12-31
Subjects: Geochemistry, Geology, Paleontology, Stratigraphy

The Ediacaran-Cambrian transition, which incorporates the radiation of animals, lacks a robust global temporal and spatial framework, resulting in major uncertainty in the evolutionary dynamics of this critical radiation and its relationship to changes in palaeoenvironmental geochemistry. We first present a new δ13Ccarb composite reference curve for the Ediacaran Nama Group of southern Namibia, [...]

Copper availability governs nitrous oxide accumulation in wetland soils and stream sediments

Neha Sharma, Elaine D. Flynn, Jeffrey G. Catalano, et al.

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

Juan Carlos Afonso, Walid Ben Mansour, Suzanne Y O’Reilly, et al.

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 crucial information on its origin and evolution that can inform energy and mineral exploration strategies, natural haz-ard mitigation and evolutionary models of the Earth1−4. However, imaging the fine-scale thermochemical structure of continental lithosphere remains a major challenge. Here we combine multiple land and satellite [...]

Elevated Post K-Pg Export Productivity in the Gulf of Mexico and Caribbean

Christopher Michael Lowery, Timothy J Bralower

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, these records come from sites so widespread that a key outstanding question is the geographic scale of changes in export [...]

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

Jagos Radovic, Wei Xie, Renzo Silva, et al.

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

Alexander Francke, Anthony Dosseto, Matt Forbes, et al.

Published: 2021-12-09
Subjects: Earth Sciences, Geochemistry, Geomorphology, Sedimentology

Shallow depth, substantial change: fluid-metasomatism causes major compositional modifications of subducted volcanics (Mariana forearc)

Elmar Albers, John W Shervais, Christian T Hansen, et al.

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

Rory Patrick Flood, Margaret Georgina Milne, Graeme T Swindles, et al.

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

Gregor Weber, Tom Sheldrake

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 [...]

Rare allanite in granulitised eclogites constrains timing of eclogite to granulite facies transition in the Bhutan Himalaya

Eleni Wood, Clare Warren, Nick M. W. Roberts, et al.

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 [...]

Plagioclase archives of depleted melts in the oceanic crust

David Axford Neave, Olivier Namur

Published: 2021-11-15
Subjects: Geochemistry, Geology

Mid-ocean ridge and ocean island basalts provide vital but incomplete insights into the chemical structure of Earth’s mantle. For example, high-anorthite plagioclase carried by these basalts is generally too primitive and incompatible-element depleted to have crystallized from them. Moreover, erupted basalts rarely preserve the strong isotopic and incompatible-element depletions found in some [...]

Stable Silicon Isotopes Uncover a Mineralogical Control on the Benthic Silicon Cycle in the Arctic Barents Sea

James Ward, Katharine Hendry, Sandra Arndt, et al.

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 [...]

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