Preprints
Filtering by Subject: Geochemistry
Observational estimates of dynamic topography through space and time
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
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 influence. 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
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 between chemically variable primitive basalts creates and modifies crystal cargoes
Published: 2021-01-13
Subjects: Geochemistry
Basaltic crystal cargoes often preserve records of mantle-derived chemical variability that have been erased from their carrier liquids by magma mixing. However, the consequences of mixing between similarly primitive but otherwise chemically variable magmas remain poorly understood despite ubiquitous evidence of chemical variability in primary melt compositions and mixing-induced disequilibrium [...]
Differences in carbon isotope discrimination between angiosperm and gymnosperm woody plants, and their geological significance
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
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
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
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
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
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 in uenced 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)
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
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?
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
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
Published: 2020-10-21
Subjects: Earth Sciences, Geochemistry, Geology, Volcanology
Copper, sourced from porphyry deposits formed in arc settings, is a critical resource, and is primarily sourced from magmas. However, the processes that shape the copper contents of arc magmas are up for debate. Existing models place emphasis on different petrological agents that explain large-scale trends in copper systematics. Previous studies have noted the 'Cu paradox,' where the magmas with [...]