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Preprints

Filtering by Subject: Geochemistry

Abrupt shift to El Niño-like mean state conditions in the tropical Pacific during the Little Ice Age

Ana Prohaska, Alistair Seddon, Bernd Meese, et al.

Published: 2022-03-11
Subjects: Climate, Earth Sciences, Geochemistry, Hydrology

The mean state of the tropical Pacific ocean-atmosphere climate, in particular its east-west asymmetry, has profound consequences for regional climates and for the El Niño/ Southern Oscillation variability. Here we present a new high-resolution paleohydrological record using the stable-hydrogen-isotopic composition of terrestrial-lipid biomarkers (δDwax) from a 1,400-year-old lake sedimentary [...]

High-resolution Ge-Si-Fe, Cr isotope and Th-U data for the Neoarchean Temagami BIF, Canada, suggest primary origin of BIF bands and oxidative terrestrial weathering 2.7 Ga ago

Michael Bau, Robert Frei, Dieter Garbe-Schoenberg, et al.

Published: 2022-03-01
Subjects: Earth Sciences, Geochemistry, Physical Sciences and Mathematics

ABSTRACT Unique deposits that formed in the Precambrian oceans are the Banded Iron-Formations (BIFs) which are chemical sediments comprised of alternating layers of iron- and silica-dominated precipitates. The origin of this enigmatic banding is still debated, with most favoring a primary sedimentary and a few others arguing for a secondary diagenetic origin. We here used a high-resolution [...]

Freshwater Suspended Particulate Matter – Key Components and Processes in Floc Formation and Dynamics.

Helene Walch, Frank von der Kammer, Thilo Hofmann

Published: 2022-02-18
Subjects: Biogeochemistry, Environmental Chemistry, Environmental Microbiology and Microbial Ecology Life Sciences, Environmental Sciences, Fresh Water Studies, Geochemistry, Hydrology, Sedimentology

Freshwater suspended particulate matter (SPM) plays an important role in many biogeochemical cycles and serves multiple ecosystem functions. Most SPM is present as complex floc-like aggregate structures composed of various minerals and organic matter from the molecular to the organism level. Flocs provide habitat for microbes and feed for larger organisms. They constitute microbial bioreactors, [...]

Early evolution of the Adelaide Superbasin

Jarred Cain Lloyd, Alan S. Collins, Morgan L. Blades, et al.

Published: 2022-02-17
Subjects: Earth Sciences, Geochemistry, Geology, Sedimentology, Stratigraphy, Tectonics and Structure

Continental rifts have a significant role in supercontinent breakup, and the development of sedimentary basins. The Australian Adelaide Superbasin is one of the largest and best-preserved rift systems that initiated during the breakup of Rodinia, yet substantial challenges still hinder our understanding of its early evolution and place within the Rodinian supercontinent. In the past decade, our [...]

PyMelt: An extensible Python engine for mantle melting calculations

Simon Matthews, Kevin Wong, Matthew Lloyd Morgan Gleeson

Published: 2022-02-13
Subjects: Earth Sciences, Geochemistry, Geology, Geophysics and Seismology, Volcanology

Modelling the melting of Earth’s mantle is crucial for understanding the distribution of volcanic activity on Earth and for testing models of mantle convection and mantle lithological heterogeneity. PyMelt is a new open-source Python library for calculating the melting behaviour of multi-lithology mantle and can be used to predict a number of geophysical and petrological observations, including [...]

Macrostratigraphy of the Ediacaran System in North America

Daniel Christian Segessenman, Shanan E Peters

Published: 2022-02-11
Subjects: Earth Sciences, Geochemistry, Geology, Paleontology, Sedimentology, Stratigraphy, Tectonics and Structure

Ediacaran sediments record the termination of Cryogenian ‘Snowball Earth’ glaciations, preserve the first occurrences of macroscopic metazoans, and contain one of the largest known negative δ13C excursions (the Shuram-Wonoka). The rock record for the transition between the Proterozoic and Phanerozoic in North America is also physically distinct, with much of the continent characterized by a wide [...]

The PATCH Lab: A database and workspace for Cenozoic terrestrial paleoclimate and environment reconstruction

Tyler Kukla, Jeremy K. C. Rugenstein, Elizabeth Driscoll, et al.

Published: 2022-02-03
Subjects: Earth Sciences, Geochemistry, Physical Sciences and Mathematics

In the last two decades, analytical advances and a growing interest in relevant research questions has brought a rapid increase in the amount of stable isotope data used for reconstructing terrestrial paleoclimates and environments. As the spatial and temporal resolution of proxy data continues to improve, the quantitative interpretation of these data is becoming increasingly common. These [...]

Powering Earth’s ancient dynamo with silicon precipitation

Alfred Wilson, Monica Pozzo, Dario Alfè, et al.

Published: 2022-01-27
Subjects: Earth Sciences, Geochemistry, Geophysics and Seismology

Earth's core has produced a global magnetic field for the last 4 Gyrs, presently sustained by inner core growth. Models of the core with high thermal conductivity suggest potentially insufficient power available for the geodynamo prior to inner core formation ~1 Ga. Precipitation of SiO2 from the liquid core might offer an alternative power source for the magnetic field before inner core [...]

Deep submarine infiltration of altered geothermal groundwater on the south Chilean Margin

Vincent J. Clementi, Yair Rosenthal, Samantha C. Bova, et al.

Published: 2022-01-25
Subjects: Earth Sciences, Geochemistry, Geology, Hydrology, Oceanography, Oceanography and Atmospheric Sciences and Meteorology, Other Earth Sciences, Physical Sciences and Mathematics

Submarine groundwater discharge is increasingly recognized as an important component of the oceanic geochemical budget, but knowledge of the distribution of this phenomenon is limited. To date, reports of meteoric inputs to marine sediments are typically limited to shallow shelf and coastal environments, whereas contributions of freshwater along deeper sections of tectonically active margins like [...]

Phanerozoic sedimentary cover history of the Hudson Platform: a heuristic modeling perspective

Kalin T. McDannell, Paul B. O'Sullivan, Kerry Gallagher, et al.

Published: 2022-01-19
Subjects: Earth Sciences, Geochemistry, Geology, Geomorphology, Physical Sciences and Mathematics, Stratigraphy, Tectonics and Structure

Understanding the long-term erosion and burial history of cratons is challenging due to the incompleteness of the rock record. Low-temperature thermochronology is used to elucidate these surface histories by inverting thermochronological data for the time-temperature history and incorporating sparse constraints and other assumptions about the regional geologic evolution. However, imposing certain [...]

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 [...]

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