Preprints
Filtering by Subject: Geochemistry
Mercury loading within the Selenga River Basin and Lake Baikal, Siberia
Published: 2019-09-28
Subjects: Biogeochemistry, Earth Sciences, Environmental Sciences, Geochemistry, Physical Sciences and Mathematics
Mercury (Hg) loading in Lake Baikal, a UNESCO world heritage site, is growing and poses a serious health concern to the lake’s ecosystem due to the ability of Hg to transform into a toxic form, known as methylmercury (MeHg). Monitoring of Hg into Lake Baikal is spatially and temporally sparse, highlighting the need for insights into historic Hg loading. This study reports measurements of Hg [...]
An image- and BET-based Monte-Carlo approach to determine mineral accessible surface areas in sandstones
Published: 2019-09-21
Subjects: Earth Sciences, Geochemistry, Physical Sciences and Mathematics
Accessible surface areas (ASAs) of individual rock-forming minerals exert a fundamental control on how minerals react with formation fluids. However, due to lacking adequate quantification methods, determining the ASAs of specific minerals in a multi-mineral rock at the appropriate scale still remains difficult. Whole-rock Brunauer-Emmett-Teller (BET) measurements at atomic scales cannot account [...]
Melt inclusion constraints on mantle carbon heterogeneity within an individual mantle plume and at the global scale
Published: 2019-09-06
Subjects: Earth Sciences, Geochemistry, Physical Sciences and Mathematics
The Earth’s mantle holds more carbon than its oceans, atmosphere and continents combined, yet the distribution of carbon within the mantle remains uncertain. Global variations in the carbon content of the depleted mantle have been inferred from carbon-trace element systematics of ultra-depleted mid-ocean ridge glasses and melt inclusions, though the origin of mantle carbon variability remains [...]
Early Paleocene Paleoceanography and Export Productivity in the Chicxulub Crater
Published: 2019-08-17
Subjects: Earth Sciences, Geochemistry, Paleontology, Physical Sciences and Mathematics, Sedimentology
The Chicxulub impact caused a crash in export productivity in much of the world’s oceans which contributed to the extinction of 75% of marine species. In the immediate aftermath of the extinction, local export productivity was highly variable, with some sites, including the Chicxulub crater, recording elevated export production. The long-term transition back to more stable export productivity [...]
Energetics of interfacial interactions of hydrocarbon fluids with kerogen and calcite using molecular modeling
Published: 2019-07-31
Subjects: Earth Sciences, Geochemistry, Physical Sciences and Mathematics
Understanding the fluid-rock interactions is essential to characterize the behavior of petroleum fluids in reservoir formations. Such knowledge is difficult to obtain due to the heterogeneous nature of hydrocarbon systems. This study investigated the interactions of light oil molecules with kerogen and calcite using molecular dynamics simulations. Specifically, octane and octanthiol were used as [...]
The Byers Basin: Jurassic-Cretaceous tectonic and depositional evolution of the forearc deposits of the South Shetland Islands and its implications for the northern Antarctic Peninsula
Published: 2019-07-31
Subjects: Earth Sciences, Geochemistry, Geology, Physical Sciences and Mathematics, Sedimentology, Stratigraphy, Tectonics and Structure
This paper addresses the Jurassic–Cretaceous stratigraphic evolution of fore-arc deposits exposed along the west coast of the northern Antarctic Peninsula. In the South Shetland Islands, Upper Jurassic deep-marine sediments are uncomformably overlain by a Lower Cretaceous volcaniclastic sequence that crops out on Livingston, Snow and Low islands. U-Pb zircon ages are presented for the upper [...]
The Gondwanan margin in West Antarctica: insights from Late Triassic magmatism of the Antarctic Peninsula
Published: 2019-07-31
Subjects: Earth Sciences, Geochemistry, Geology, Physical Sciences and Mathematics, Tectonics and Structure
Triassic orthogneisses of the Antarctic Peninsula provide evidence for the Palaeozoic and Mesozoic geological evolution of southern Gondwana within Pangaea. These rocks are sporadically exposed in southeastern Graham Land and northwestern Palmer Land, although reliable geochronological, geochemical and isotopic data are sparse. We combine new geochronological (LA-ICP-MS zircon U-Pb), geochemical, [...]
Relationships between soil chemical properties and rare earth element concentrations in the aboveground biomass of a tropical herbaceous plant
Published: 2019-07-18
Subjects: Biogeochemistry, Earth Sciences, Geochemistry, Physical Sciences and Mathematics
The geochemical behavior of rare earth elements (REE) has been mainly investigated in geological systems where they represent the best proxies for processes occurring at the interface between different media. REE concentrations, normalized with respect to the upper continental crust, were used to assess their behavior. In this study, REE geochemical behavior was investigated in plant shoots of a [...]
δ13C values of bacterial hopanoids and leaf waxes as tracers for methanotrophy in peatlands
Published: 2019-07-09
Subjects: Biogeochemistry, Earth Sciences, Geochemistry, Physical Sciences and Mathematics
Methane emissions from peatlands contribute significantly to atmospheric CH4 levels and play an essential role in the global carbon cycle. The stable carbon isotopic composition (δ13C) of bacterial and plant lipids has been used to study modern and past peatland biogeochemistry, especially methane cycling. However, the small number of recent peatlands that have been characterised and the lack of [...]
The impact of Mg2+ ions on equilibration of Mg-Ca carbonates in groundwater and brines
Published: 2019-07-04
Subjects: Earth Sciences, Geochemistry, Physical Sciences and Mathematics
At temperatures below 50°C, the Mg2+/Ca2+ values in groundwater and brines, irrespective of their origin - either carbonaceous or siliceous rocks/sediments - show a large spread. As shown by equilibria of surface layer composition of calcite in solutions containing Mg2+ , log10 (aMg2+ /a Ca2+) vary between minus infinity and +2.3, thereby covering thermodynamical equilibria between the minerals [...]
Tracing the migration of mantle CO2 in gas fields and mineral water springs in south-east Australia using noble gas and stable isotopes
Published: 2019-06-18
Subjects: Earth Sciences, Geochemistry, Physical Sciences and Mathematics
Geochemical monitoring of CO2 storage requires understanding of both innate and introduced fluids in the crust as well as the subsurface processes that can change the geochemical fingerprint of CO2 during injection, storage and any subsequent migration. Here, we analyse a natural analogue of CO2 storage, migration and leakage to the atmosphere, using noble gas and stable isotopes to constrain the [...]
Stepwise chemical abrasion–isotope dilution–thermal ionization mass spectrometry with trace element analysis of microfractured Hadean zircon
Published: 2019-06-16
Subjects: Earth Sciences, Geochemistry, Geology, Physical Sciences and Mathematics
The Hadean Jack Hills zircons represent the oldest known terrestrial material, providing a unique and truly direct record of Hadean Earth history. This zircon population has been extensively studied via high spatial resolution, high throughput in situ isotopic and elemental analysis techniques such as secondary ionization mass spectrometry (SIMS), but not by comparatively destructive, [...]
Evaluating the relationship between the area and latitude of large igneous provinces and Earth’s long-term climate state
Published: 2019-06-12
Subjects: Earth Sciences, Geochemistry, Geology, Physical Sciences and Mathematics, Tectonics and Structure
One of the hypothesized effects of large igneous provinces (LIPs) is planetary cooling on million-year timescales associated with enhanced silicate weathering of the freshly-emplaced basalt. This study combines reconstructions of the original surface extent and emplacement ages of LIPs, a paleogeographic model, and a parameterization of LIP erosion to estimate LIP area in all latitudinal bands [...]
Comments on, Scaled Random Number Simulation of High Correlation Coeffieients for Gasoline Range Compound Concentrations (unpublished results), disclosed in EarthArXiv, 5 April, 2019, by Lloyd R. Snowdon.
Published: 2019-05-30
Subjects: Earth Sciences, Geochemistry, Physical Sciences and Mathematics
The paper comments on disclosure EarthArXiv 5 April, 2019 by L. R. Snowdon discounting correlations between light hydrocarbons suggesting steady-state catalysis in the origin of petroleum. The correlations are shown to be valid and Snowdons arguments not relevant.
A constant Chinese Loess Plateau dust source since the Late Miocene
Published: 2019-05-30
Subjects: Earth Sciences, Geochemistry, Geology, Physical Sciences and Mathematics
The Pliocene-Pleistocene boundary marks a major change in global climate and East Asian monsoon dynamic. However, the role of the global atmospheric dust-cycle over this time is unclear; in particular, whether, changes in the dust cycle influenced climate change, or resulted from it. Chinese loess records past dust-cycle history and the influences of aridification and monsoon circulation over the [...]