Preprints

Filtering by Subject: Geochemistry

Observational estimates of dynamic topography through space and time

Mark Hoggard, Jacqueline Austermann, Cody Randel, Simon Stephenson

Published: 2021-01-24
Subjects: Biogeochemistry, Cosmochemistry, Earth Sciences, Geochemistry, Geology, Geomorphology, Geophysics and Seismology, Paleobiology, Physical Sciences and Mathematics, Sedimentology, Stratigraphy, Tectonics and Structure, Volcanology

Earth's mantle undergoes convection on million-year timescales as heat is transferred from depth to the surface. Whilst this flow has long been linked to the large-scale horizontal forces that drive plate tectonics and supercontinent cycles, geologists are increasingly recognising the signature of convection through transient vertical motions in the rock record, known as "dynamic topography". A [...]

Evidence confirms an anthropic origin of Amazonian Dark Earths

Umberto Lombardo, Manuel Arroyo-Kalin, Hans Huisman, Wenceslau Geraldes Teixeira, Charles R Clement, Carlos Francisco Brazão Vieira Alho, Fernando Almeida, Lucia Helena Cunha Anjos, Christopher Bronk Ramsey, George Brown, Marcondes Costa, Luis Cunha, William M Denevan, Ademir Fontana, Bruno Glaser, Susanna Hecht, Klaus A Jarosch, André Braga Junqueira, Thiago Kater, Thomas W Kuyper, Johannes Lehmann, Helena Pinto Lima, Rodrigo Santana Macedo, Marco Madella, S. Yoshi Maezumi, Francis E Mayle, Doyle McKEY, Claide de Paula Moraes, Gaspar Morcote-Ríos, Eduardo Neves, Francisco Pugliese, Fabiano Pupim, Marco F Raczka, Anne Rapp Py-Daniel, Philip Riris, Leonor Rodrigues, Stéphen Rostain, Morgan Schmidt, Myrtle P Shock, Tobias Sprafke, Eduardo Kazuo Tamanaha, Pablo Vidal-Torrado, Ximena S Villagran, Jennifer Watling, Sadie L Weber

Published: 2021-01-22
Subjects: Biogeochemistry, Earth Sciences, Geochemistry, Geomorphology, Physical Sciences and Mathematics, Soil Science

First described over 120 years ago in Brazil, Amazonian Dark Earths (ADEs) are expanses of dark soil that are exceptionally fertile and contain large quantities of archaeological artefacts. The elevated fertility of the dark and often deep A horizon of ADEs is widely regarded as an outcome of pre-Columbian human influence1. Controversially, in their recent paper Silva et al.2argue that the higher [...]

Integrated magnetotelluric and petrological analysis of felsic magma reservoirs: Insights from Ethiopian rift volcanoes

Friedemann Samrock, Alexander V. Grayver, Olivier Bachmann, Özge Karakas, Martin O Saar

Published: 2021-01-16
Subjects: Earth Sciences, Geochemistry, Geophysics and Seismology, Volcanology

Geophysical and petrological probes are key to understanding the structure and the thermochemical state of active magmatic systems. Recent advances in laboratory analyses, field investigations and numerical methods have allowed increasingly complex data-constraint models with new insights into magma plumbing systems and melt evolution. However, there is still a need for methods to quantitatively [...]

Mixing-induced chemical disequilibrium creates and modifies basaltic crystal cargoes

David Axford Neave, Philipp Beckmann, Harald Behrens, Francois Holtz

Published: 2021-01-13
Subjects: Geochemistry

Crystal cargoes of oceanic basalts often preserve records of mantle-derived chemical variability that are erased from their carrier melts by magma mixing. However, the impacts of mixing between similarly primitive but chemically variable magmas remain poorly understood despite ubiquitous evidence of chemical variability in primary melt compositions and chemical disequilibrium in erupted crystal [...]

Differences in carbon isotope discrimination between angiosperm and gymnosperm woody plants, and their relationship to atmospheric O2:CO2 ratio, physiology, and environment

Vincent John Hare, Aliénor Lavergne

Published: 2020-12-13
Subjects: Biogeochemistry, Climate, Geochemistry, Oceanography and Atmospheric Sciences and Meteorology, Paleobiology

For most of the Phanerozoic Eon, Earth’s woody vegetation has been dominated by C3 plants – predominantly gymnosperms - with angiosperms only emerging as the dominant plant group as CO2 declined during the Cenozoic (66 Ma onward). At present, differences in carbon isotope discrimination (Δ13C) between angiosperm and gymnosperm plants are relatively small (2–3 ‰), but an increasing body of [...]

VESIcal Part I: An open-source thermodynamic model engine for mixed volatile (H2O-CO2) solubility in silicate melts

Kayla Iacovino, Simon Matthews, Penny E Wieser, Gordon Moore, Florence Bégué

Published: 2020-12-08
Subjects: Earth Sciences, Geochemistry, Geology, Physical Sciences and Mathematics, Planetary Geochemistry, Planetary Geology, Planetary Sciences, Volcanology

Thermodynamics has been fundamental to the interpretation of geologic data and modeling of geologic systems for decades. However, more recent advancements in computational capabilities and a marked increase in researchers’ accessibility to computing tools has outpaced the functionality and extensibility of currently available modeling tools. Here we present VESIcal (Volatile Equilibria and [...]

Stalagmite carbon isotopes suggest deglacial increase in soil respiration in Western Europe driven by temperature change

Franziska Lechleitner, Christopher C. Day, Oliver Kost, Micah Wilhelm, Negar Haghipour, Gideon M. Henderson, Heather M. Stoll

Published: 2020-12-02
Subjects: Biogeochemistry, Climate, Earth Sciences, Geochemistry, Physical Sciences and Mathematics, Speleology

The temperate region of Western Europe underwent dramatic climatic and environmental change during the last deglaciation. Much of what is known about the terrestrial ecosystem response to deglacial warming stems from pollen preserved in sediment sequences, providing information on vegetation composition. Other ecosystem processes, such as soil respiration, remain poorly constrained over past [...]

Chemistry speedup in reactive transport simulations: purely data-driven and physics-based surrogates

Marco De Lucia, Michael Kühn

Published: 2020-11-30
Subjects: Earth Sciences, Geochemistry

The computational costs associated with coupled reactive transport simulations are mostly due to the chemical subsystem: replacing it with a pre-trained statistical surrogate is a promising strategy to achieve decisive speedups at price of small accuracy losses and thus to extend the scale of problems which can be handled. We introduce a hierarchical coupling scheme in which ``full [...]

A Vision for the Future Low-Temperature Geochemical Data-scape

Susan L. Brantley, Tao Wen, Deb Agarwal, Jeff Catalano, Paul A. Schroeder, Kerstin Lehnert, Charuleka Varadharajan, Julie Pett-Ridge, Mark Engle, Anthony M. Castronova, Rick Hooper, Xiaogang Ma, Lixin Jin, Kenton McHenry, Emma Aronson, Andrew Shaughnessy, Lou Derry, Justin Richardson, Jerad Bales, Eric Pierce

Published: 2020-11-21
Subjects: Biogeochemistry, Computer Sciences, Databases and Information Systems, Earth Sciences, Environmental Sciences, Geochemistry, Geology, Geomorphology, Hydrology, Other Computer Sciences, Other Earth Sciences, Soil Science

Data sharing benefits the researcher, the scientific community, and most importantly, the public by enabling more impactful analysis of data and greater transparency in scientific research. However, like many other scientists, the low-temperature geochemistry (LTG) community has generally not developed protocols and standards for publishing, citing, and versioning datasets. This paper is the [...]

Boron isotopic signatures of melt inclusions from North Iceland reveal recycled material in the Icelandic mantle source

Margaret Hartley, Oliver Shorttle, Cees-Jan de Hoog

Published: 2020-11-13
Subjects: Earth Sciences, Geochemistry, Geology, Physical Sciences and Mathematics, Volcanology

Trace element and volatile heterogeneity in the Earth's mantle is inuenced by the recycling of oceanic lithosphere through subduction. Oceanic island basalts commonly have high concentrations of volatiles compared to mid-ocean ridge basalts, but the extent to which this enrichment is linked to recycled mantle domains remains unclear. Boron is an ideal tracer of recycled subducted material, [...]

1600 year-long sedimentary record of tsunamis and hurricanes in the Lesser Antilles (Scrub Island, Anguilla)

Maude BIGUENET, Pierre Sabatier, Eric Chaumillon, Catherine Chagué, Fabien Arnaud, Frans Jorissen, Thibault Coulombier, Emeline Geba, Louise Cordrie, Pierre Vacher, Anne-Lise Develle, Emilie Chalmin, Fayçal Soufi, Nathalie Feuillet

Published: 2020-10-22
Subjects: Geochemistry, Oceanography, Sedimentology

The Lesser Antilles are a densely populated and a very touristic region exposed to many short-term hazards such as hurricanes and tsunamis. However, the historical catalog of these events is too short to allow risk assessment and return period estimations, and it needs to be completed with long-term geological records. Two sediment cores were sampled in March 2018 in a small coastal lagoon on [...]

Modulation of riverine concentration-discharge relationships by changes in the shape of the water transit time distribution

Mark Albert Torres, J. Jotautas Baronas

Published: 2020-10-21
Subjects: Geochemistry, Hydrology

The concentrations of weathering-derived solutes in rivers and their co-variance with discharge are thought to reflect reactive-transport processes in hillslopes and to reveal the sensitivity of solute fluxes to climatic change. It is expected that discharge-driven changes in water transit times play some role in setting concentration-discharge (C-Q) relationships, but knowledge gaps remain. To [...]

The global melt inclusion C/Ba array: mantle variability, melting process, or degassing?

Simon Matthews, Oliver Shorttle, John Maclennan, John F Rudge

Published: 2020-10-21
Subjects: Earth Sciences, Geochemistry

The Earth’s mantle holds more carbon than its oceans, atmosphere and continents combined, yet the distribution of carbon within the mantle remains uncertain. Our best constraints on the distribution of carbon within the upper mantle are derived from the carbon-trace element systematics of ultra-depleted glasses and melt inclusions from mid-ocean ridge basalts. However, carbon-trace element [...]

Dynamics of core-mantle separation: influence of viscosity contrast and metal/silicate partition coefficients on the chemical equilibrium

Vincent Clesi, Julien Monteux, Baraa Qaddah, Michael Le Bars, Jean-Baptiste Wacheul, Mohamed Ali Bouhifd

Published: 2020-10-21
Subjects: Earth Sciences, Geochemistry, Geophysics and Seismology, Physical Sciences and Mathematics

The composition of the Earth's core and mantle is set by the chemical equilibrium between metals and silicates during core/mantle segregation. The metallic core separated from the mantle by gravitational descent in the form of diapirs in a magma ocean, and therefore the dynamics of the diapir's downward movement has an influence on the chemical equilibrium. In this study, we characterize the [...]

Amphibole Control on Copper Systematics in Arcs: Insights from the Analysis of Global Datasets

Nicholas Dewitt Barber, Marie Edmonds, Frances Jenner, Andreas Audétat, Helen Williams

Published: 2020-10-21
Subjects: Earth Sciences, Geochemistry, Geology, Volcanology

Copper, sourced from porphyry deposits formed in arc settings, is an increasingly scarce yet critical resource. The processes that shape the copper contents of magmas remain poorly understood. One theory is that magmas must be copper-rich in order to form porphyry deposits. Mature arcs have up to now played an outsized role in shaping existing models of copper systematics in magmas. Here we take [...]

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