Preprints

Filtering by Subject: Geochemistry

SOLUBILITY PRODUCT CONSTANTS FOR NATURAL DOLOMITE (0-200°C) THROUGH A GROUNDWATER-BASED APPROACH USING THE USGS PRODUCED WATER DATABASE – PART A

Hamish Robertson, Fiona Whitaker, Cathy Hollis, Hilary Corlett

Published: 2021-05-02
Subjects: Earth Sciences, Geochemistry

The calculation of a reliable temperature dependent dolomite solubility product constant (Ksp°−dol) has been the subject of much research over the last 70 years. This study evaluates log10(aCa2+/aMg2+) using PHREEQC (Pitzer approach) for a screened subset (n=11,480) of formation waters in the U.S. Geological Survey National Produced Waters Geochemical Database V2 (PWGD), an extensive inventory of [...]

Late Paleozoic–Early Mesozoic granitoids in the Khangay–Khentey basin, Central Mongolia: Implication for the tectonic evolution of the Mongol–Okhotsk Ocean margin

Ariuntsetseg Ganbat, Tatsuki Tsujimori, Laicheng Miao, Inna Safonova, Daniel Pastor-Galán, Chimedtseren Anaad, Munkhtsengel Baatar, Shogo Aoki, Kazumasa Aoki, Ilya Savinskiy

Published: 2021-04-26
Subjects: Geochemistry, Geology

The Mongol–Okhotsk Belt is the youngest segment of the Central Asian Orogenic Belt, which is the venue of the massive juvenile crust emplacement, and it is formation and evolutions are still pending problems. This paper presents the first up-to-date U-Pb zircon ages, Hf-in-zircon isotope, geochemical and whole-rock Nd isotope data from igneous rocks of the Khangay–Khentey basin, Central Mongolia. [...]

Unmixing river sediments for the elemental geochemistry of their source regions

Alex Lipp, Gareth Roberts, Alexander C Whittaker, Charles J. B. Gowing, Victoria Fernandes

Published: 2021-04-15
Subjects: Earth Sciences, Geochemistry, Physical Sciences and Mathematics

The geochemistry of river sediments is routinely used to obtain information about geologic and environmental processes occurring upstream. For example, downstream samples are used to constrain chemical weathering and physical erosion rates, as well as the locations of mineral deposits or contaminant sources. Previous work has shown that, by assuming conservative mixing, the geochemistry of [...]

A global hydrothermal reactor triggered prebiotic synthesis on Earth

Chiara Boschi, Andrea Dini, Gretchen L. Früh-Green, Luca Caricchi

Published: 2021-04-15
Subjects: Biogeochemistry, Earth Sciences, Geochemistry, Geology, Planetary Geology

Biosignatures in the rock record limit the time available for life to start on Earth to 600-800 million years1 (4.5-3.7 Ga; Hadean-Archean). Whether the conditions for the synthesis of complex organic molecules were unique to this time or remain present today is unclear, but understanding these conditions is essential for the search of life on other planets. The outer portion of the Hadean Earth [...]

Paleoclimate Changes in the Pacific Northwest Over the Past 36,000 Years from Clumped Isotope Measurements and Isotope-Enabled Model Analysis

Ricardo Lopez-Maldonado, Jesse Bateman, Andre Ellis, Nicholas E. Bader, Pedro Ramirez, Alexandrea Arnold, Osinachi Ajoku, Hung-I Lee, Gregory Jesmok, Deepshikha Upadhyay, Bryce Mitsunaga, Ben Elliott, Clay Tabor, Aradhna Tripati

Published: 2021-04-07
Subjects: Climate, Geochemistry, Geology, Physical Sciences and Mathematics, Soil Science

Since the last glacial period, North America has experienced dramatic changes in regional climate, including the collapse of ice sheets and changes in effective precipitation. We use clumped isotopes and analysis of transient climate simulations to provide constraints on hydroclimate changes in the Pacific Northwest. The coldest soil temperatures (~10.5 ±1.°C to 14.9 ±1.2°C) occurred [...]

Silurian carbonate high-energy deposits of potential tsunami origin: distinguishing lateral redeposition and time averaging using carbon isotope chemostratigraphy

Emilia Jarochowska, Axel Munnecke

Published: 2021-03-17
Subjects: Earth Sciences, Geochemistry, Geology, Sedimentology, Stratigraphy

Stable carbon isotope curves are used as a precise stratigraphic tool in the Paleozoic, even though they are commonly based on shallow-water carbonate record, characterized by low stratigraphic completeness. Identification of episodes of large-scale redeposition and erosion may improve δ13Ccarb-based correlations. Here, a series of at least three episodes of high-energy onshore redeposition are [...]

Lithologic Controls on Silicate Weathering Regimes of Temperate Planets

Kaustubh Hakim, Dan J. Bower, Meng Tian, Russell Deitrick, Pierre Auclair-Desrotour, Daniel Kitzmann, Caroline Dorn, Klaus Mezger, Kevin Heng

Published: 2021-03-12
Subjects: Astrophysics and Astronomy, Earth Sciences, Geochemistry, Planetary Geochemistry, Planetary Sciences

Weathering of silicate rocks at a planetary surface can draw down CO2 from the atmosphere for eventual burial and long-term storage in the planetary interior. This process is thought to provide essential negative feedback to the carbonate-silicate cycle (carbon cycle) to maintain clement climates on Earth and potentially similar temperate exoplanets. We implement thermodynamics to determine [...]

The Ca and Mg isotope record of the Cryogenian Trezona carbon isotope excursion

Anne-Sofie Crüger Ahm, Christian J Bjerrum, Paul F Hoffman, Francis A Macdonald, Adam C Maloof, Catherine V Rose, Justin V. Strauss, John A Higgins

Published: 2021-03-11
Subjects: Earth Sciences, Geochemistry, Geology, Sedimentology, Stratigraphy

The Trezona carbon isotope excursion is recorded on five different continents in platform carbonates deposited prior to the end-Cryogenian Marinoan glaciation (>635 Ma) and represents a change in carbon isotope values of 16-18 per mill. Based on the spatial and temporal reproducibility, the excursion previously has been interpreted as tracking the carbon isotopic composition of dissolved [...]

Crisis at the Salton Sea: Research Gaps and Opportunities

Marilyn Fogel, Hoori Ajami, Emma Aronson, Roya Bahreini, Wilfred Elders, Darrel Jenerette, David Lo, Timothy Lyons, Michael McKibben, William Porter, Arun Raju, Kurt Schwabe, Caroline Hung, Jonathan Nye

Published: 2021-03-04
Subjects: Atmospheric Sciences, Biogeochemistry, Chemistry, Climate, Earth Sciences, Environmental Chemistry, Environmental Public Health, Environmental Sciences, Environmental Studies, Geochemistry, Geology, Geomorphology, Hydrology, Medicine and Health Sciences, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics, Public Health, Social and Behavioral Sciences

The Salton Sea, a hypersaline lake in southern California, USA, is in crisis. A combination of mismanagement and competition between federal, state and local agencies has resulted in stalled efforts to address dropping water levels and unstable lake biogeochemistry. This in turn has led to a growing public health crisis as exposed shoreline exposes potentially toxic dust to local and regional [...]

Evidence for crustal removal, tectonic erosion and flare-ups from the Japanese evolving forearc sediment provenance

Daniel Pastor-Galán, Christopher Spencer, Tan Furukawa, Tatsuki Tsujimori

Published: 2021-02-24
Subjects: Earth Sciences, Geochemistry, Geology, Tectonics and Structure

Forearc basins preserve the geologic record relating strictly to arc magmatism. The provenance of forearc sediment can be used to differentiate periods of crustal growth, accretion, and destruction, enhanced magmatism, advancing and retreating subduction slabs, delamination, etc. All these tectonic events systems predict differing degrees of sedimentary reworking of the older forearc units. [...]

Insights into the nature of plume-ridge interaction and outflux of H2O from the Galápagos Spreading Centre

Matthew Lloyd Morgan Gleeson, Sally Gibson

Published: 2021-02-18
Subjects: Earth Sciences, Geochemistry, Other Earth Sciences, Physical Sciences and Mathematics, Volcanology

The flow of high-temperature and compositionally-enriched material between mantle plumes and nearby spreading centres influences up to 30% of the global mid-ocean ridge system and represents a significant, but currently unconstrained, flux of volatiles out of the mantle. Here we present new analyses of H2O, F, Cl and S in basaltic glass chips from an archetypal region of plume-ridge interaction, [...]

234U/230Th coral growth dating yields reliable ages in restricted basins despite anomalous δ234Ui values

Jenni Robertson, Diana Sahy, Gerald P Roberts, Marco Meschis

Published: 2021-02-10
Subjects: Geochemistry, Geology, Tectonics and Structure

Late Quaternary coral growth ages from uplifted coastal regions, such as marine terraces and associated palaeoshorelines, are an essential tool used to derive tectonic and fault controlled uplift and deformation rates, and thus contribute to seismic hazard analysis and constrain past global sea levels. Fossil coral growth ages are assessed for reliability based upon whether the δ234Ui (or [...]

Classification, segmentation and correlation of zoned minerals

Tom Sheldrake, Oliver John Higgins

Published: 2021-02-01
Subjects: Earth Sciences, Environmental Sciences, Geochemistry, Geology, Numerical Analysis and Scientific Computing, Statistics and Probability, Volcanology

Minerals exhibit zoning patterns that can be related to changes in the environment in which they grew. Using statistical methods that have been designed to segment optical images, we have developed a procedure to segment zonation within minerals and correlate these zones between multiple crystals using elemental maps. This allows us to quantify the complexity and variability of chemical zoning [...]

Ordination analysis in sedimentology, geochemistry and paleoenvironment - background, current trends and recommendations

Or M. Bialik, Emilia Jarochowska, Michal Grossowicz

Published: 2021-02-01
Subjects: Biogeochemistry, Earth Sciences, Environmental Indicators and Impact Assessment, Environmental Monitoring, Geochemistry, Geology, Geomorphology, Geophysics and Seismology, Glaciology, Multivariate Analysis, Oil, Gas, and Energy, Other Earth Sciences, Paleobiology, Paleontology, Sedimentology

Ordination is the name given to a group of methods used to analyze multiple variables without preceding hypotheses. Over the last few decades the use of these methods in Earth science in general, and notably in analyses of sedimentary sources, has dramatically increased. However, with limited resources oriented towards Earth scientists on the topic, the application of ordination analysis is at [...]

Quantitative chemical mapping of plagioclase as a tool for the interpretation of volcanic stratigraphy: an example from Saint Kitts, Lesser Antilles

Oliver John Higgins, Tom Sheldrake, Luca Caricchi

Published: 2021-02-01
Subjects: Earth Sciences, Geochemistry, Geology, Stratigraphy, Volcanology

Establishing a quantitative link between magmatic processes occurring at depth and volcanic eruption dynamics is essential to forecast the future behaviour of volcanoes, and to correctly interpret monitoring signals at active centres. Chemical zoning in minerals, which captures successive events or states within a magmatic system, can be exploited for such a purpose. However, to develop a [...]

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