Preprints

Filtering by Subject: Geochemistry

Evolution of diversity in the editorial boards of Geochimica et Cosmochimica Acta and Chemical Geology

Olivier Pourret, Pallavi Anand, Pieter Bots, et al.

Published: 2022-06-24
Subjects: Geochemistry, Physical Sciences and Mathematics

Background: Editorial board members of academic journals are often considered gatekeepers of knowledge and role models for the community. Editorial boards should have sufficiently diverse backgrounds to facilitate the publication of manuscripts with a wide range of research paradigms, methods, and cultural perspectives. Objectives: This study critically evaluates changes in the representation of [...]

Pervasive carbonation of peridotite to listvenite (Semail Ophiolite, Sultanate of Oman): clues from iron partitioning and chemical zoning

Thierry Decrausaz, Marguerite Godard, Manuel D. Menzel, et al.

Published: 2022-06-21
Subjects: Geochemistry, Geology

Earth’s long-term cycling of carbon is regulated from mid-ocean ridges to convergent margins by mass transfers involving mantle rocks. Here we examine the conversion of peridotite into listvenite (magnesite+quartz) occurring along the basal thrust of the Semail Ophiolite (Fanja, Sultanate of Oman). At the outcrop scale, this transformation defines reaction fronts, from serpentinized peridotites, [...]

Validation of glacial-interglacial rainfall variations in southwest Sulawesi using Mg/Ca and δ18O in speleothems

Alena K Kimbrough, Michael Gagan, Gavin Dunbar, et al.

Published: 2022-06-17
Subjects: Atmospheric Sciences, Climate, Earth Sciences, Geochemistry, Hydrology, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics, Speleology

Speleothem δ18O is widely used as a proxy for rainfall amount in the tropics on glacial-interglacial to interannual scales. However, uncertainties in the interpretation of this renowned proxy pose a vexing problem in tropical paleoclimatology. Here, we present paired measurements of Mg/Ca and δ18O for multiple stalagmites from southwest Sulawesi, Indonesia, that that confirm changes in rainfall [...]

The historical impact of anthropogenic air-borne sulphur on the Pleistocene rock art of Sulawesi

Michael Gagan, Halmar Halide, Raden Permana, et al.

Published: 2022-05-31
Subjects: Earth Sciences, Environmental Indicators and Impact Assessment, Environmental Sciences, Geochemistry, Natural Resources and Conservation

The Maros-Pangkep karst in southwest Sulawesi, Indonesia, contains some of the world’s oldest rock art. However, the Pleistocene images survive only as weathered patches of pigment on exfoliated limestone surfaces. Salt efflorescence underneath the case-hardened limestone substrate causes spall-flaking, and it has been proposed that the loss of artwork has accelerated over recent decades. Here, [...]

Paleoclimate controls on lithium enrichment in Great Basin Pliocene-Pleistocene lacustrine clays

Catherine A Gagnon, Kristina Butler, Elizabeth Gaviria, et al.

Published: 2022-05-29
Subjects: Climate, Earth Sciences, Environmental Sciences, Geochemistry, Geology, Natural Resources and Conservation, Other Environmental Sciences, Sedimentology

Terminal lakes are important archives of continental hydroclimate and in some cases contain important economic resources. Here we present an ~3.6 Myr lacustrine carbonate carbon and oxygen stable isotope record from a Great Basin continental drill core. We pair these measurements with bulk lithium concentrations to reveal a relationship between past climate and lithium enrichment in authigenic [...]

A very unconventional hydrocarbon play: the Mesoproterozoic Velkerri Formation of Northern Australia

Grant Cox, Alan S. Collins, Amber J.M. Jarrett, et al.

Published: 2022-05-16
Subjects: Geochemistry, Geology, Sedimentology, Stratigraphy, Tectonics and Structure

The ca. 1.5–1.3 Ga Roper Group of the greater McArthur Basin is a component of one of the most extensive Precambrian hydrocarbon-bearing basins preserved in the geological record, recently assessed as containing 429 million barrels of oil and eight trillion cubic feet of gas (in place). It was deposited in an intra-cratonic sea, referred to here as the McArthur-Yanliao Gulf. The Velkerri [...]

Quantifying excess heavy metal concentrations in drainage basins using conservative mixing modelling

Jonas Alexander Eschenfelder, Alex G. Lipp, Gareth G Roberts

Published: 2022-05-13
Subjects: Earth Sciences, Environmental Sciences, Geochemistry, Geomorphology, Physical Sciences and Mathematics, Sustainability, Water Resource Management

High concentrations of heavy metals and other pollutants in river sediments can have detrimental effects on the health of ecosystems and humans. As such, determining the composition of river sediments throughout drainage basins is an essential aspect of environmental monitoring. Well characterised natural baseline concentrations are important information with which observations can be compared [...]

The CREp 36Cl exposure age calculator: development version “dev”

Irene Schimmelpfennig, Pierre-Henri BLARD, Jim Tesson, et al.

Published: 2022-05-04
Subjects: Geochemistry, Geology, Geomorphology, Glaciology, Sedimentology, Tectonics and Structure, Volcanology

Chlorine-36 (36Cl) is currently the only in situ cosmogenic nuclide applicable in carbonates, Ca- and K-rich feldspars and aphyric silicate rocks. Because the production reactions of 36Cl are more numerous and complex than those of other cosmogenic nuclides (e.g. 10Be, 3He), comprehensive and user-friendly calculators are essential for routine application of 36Cl to Earth surface research [...]

Radiogenic isotope: not just about words

Olivier Pourret, Karen Johannesson

Published: 2022-04-30
Subjects: Earth Sciences, Geochemistry

This viewpoint is a short comment on gender issues with isotope terminology. The terms "parent"/"daughter" should be avoided in favor of the more descriptive "precursor ion" and "product ion" terms.

Expansion and intensification of the North American Monsoon during the Pliocene

Tripti Bhattacharya, Ran Feng, Jessica Tierney, et al.

Published: 2022-04-14
Subjects: Climate, Earth Sciences, Geochemistry, Oceanography and Atmospheric Sciences and Meteorology

Southwestern North America, like many subtropical regions, is predicted to become drier in response to anthropogenic warming. However, during the Pliocene, when carbon dioxide was above pre-industrial levels, multiple lines of evidence suggest that southwestern North America was much wetter. While existing explanations for a wet Pliocene invoke increases in winter rain, recent modeling studies [...]

Late Glacial and Holocene Palaeolake History of the Última Esperanza Region of Southern Patagonia

Stephen J Roberts, Robert D McCulloch, Joseph F Emmings, et al.

Published: 2022-03-29
Subjects: Earth Sciences, Geochemistry, Geology, Geomorphology, Glaciology, Hydrology, Paleobiology, Physical Sciences and Mathematics, Sedimentology, Stratigraphy, Volcanology

We undertook multiproxy analyses on two sediment cores from Lago Pato, a small lake basin at 51°S topographically separated from Lago del Toro in Torres del Paine (TdP), to provide insights into glacier dynamics and lake level change in the TdP and Última Esperanza region over the last ~30,000 cal a BP (30 ka). Lago Pato is situated in a region overridden by the Southern Patagonian Icefield [...]

Detrital zircon record of the Sturtian glaciation: Adelaide Superbasin

Jarred Cain Lloyd, Wolfgang V Preiss, Alan S. Collins, et al.

Published: 2022-03-24
Subjects: Earth Sciences, Geochemistry, Geology, Sedimentology, Stratigraphy

The glaciogenic nature of the Yudnamutana Subgroup was first recognised over a century ago, and their global significance was recognised shortly after, eventually culminating with the pan global Sturtian glaciation and Snowball Earth theory. Much debate on the origin and timing of these rocks, locally and globally, has ensued in the years since. A significant corpus of research on the lithology, [...]

Late Tonian development and provenance of the Adelaide Superbasin

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

Published: 2022-03-22
Subjects: Earth Sciences, Geochemistry, Geology, Sedimentology, Stratigraphy, Tectonics and Structure

The late Tonian sequences of the Adelaide Superbasin were witness to the birth of the proto-Pacific Ocean during the breakup of Rodinia. Understanding the sedimentology and provenance of these rocks from across the basin is key to understanding both their deposition over ~70 million years, the local palaeogeography, and leads to a better understanding of the early development of the proto-Pacific [...]

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 [...]

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