Preprints

Filtering by Subject: Cosmochemistry

Jarosite formation in deep Antarctic ice provides a window into acidic, water-limited weathering on Mars

Giovanni Baccolo, Barbara Delmonte, Paul B. Niles, Giannantonio Cibin, Elena Di Stefano, Dariush Hampai, Lindsay Keller, Valter Maggi, Augusto Marcelli, Joseph Michalski

Published: 2020-05-20
Subjects: Cosmochemistry, Earth Sciences, Geochemistry, Physical Sciences and Mathematics, Planetary Geochemistry, Planetary Glaciology, Planetary Sciences

Many interpretations have been proposed to explain the presence of jarosite within Martian surficial sediments, including the possibility that it precipitated within paleo-ice deposits owing to englacial weathering of dust. But until now a similar mechanism was not observed on Earth nor in other planetary settings. We report the first multi-analytical indication of jarosite formation within deep [...]

International disparities in open access practices of the Earth Sciences community

Olivier Pourret, David William Hedding, Dasapta Erwin Irawan, Haiyan Liu, Jonathan Tennant

Published: 2020-03-31
Subjects: Biogeochemistry, Cosmochemistry, Earth Sciences, Geochemistry, Geology, Geomorphology, Geophysics and Seismology, Glaciology, Hydrology, Library and Information Science, Mineral Physics, Other Earth Sciences, Paleobiology, Paleontology, Physical Sciences and Mathematics, Sedimentology, Social and Behavioral Sciences, Soil Science, Speleology, Stratigraphy, Tectonics and Structure, Volcanology

Short communication on international disparities in open access practices of the Earth Sciences community

On the potential of preprints in geochemistry: the good, the bad and the ugly

Olivier Pourret, Dasapta Erwin Irawan, Jonathan Tennant

Published: 2020-03-21
Subjects: Biogeochemistry, Cosmochemistry, Earth Sciences, Geochemistry, Library and Information Science, Physical Sciences and Mathematics, Social and Behavioral Sciences

Short communication on the use of preprint in geochemistry

Causation of Late Quaternary Rapid-increase Radiocarbon Anomalies

G. BRAKENRIDGE

Published: 2019-05-07
Subjects: Astrophysics and Astronomy, Cosmochemistry, Earth Sciences, Physical Sciences and Mathematics

Brief (<100 y) rapid-increase anomalies in the Earth’s atmospheric 14C production have previously been attributed to either gamma photon radiation from supernovae or to cosmic ray particle radiation from exceptionally large solar flares. Analysis of distances and ages of nearby supernovae (SNe) remnant surveys, the probable gamma emissions, the predicted Earth-incident radiation, and the [...]

Introduction to Geochronology

Pieter Vermeesch

Published: 2017-12-29
Subjects: Cosmochemistry, Earth Sciences, Geochemistry, Physical Sciences and Mathematics

These lecture notes cover the first half of an Isotope Geology module at University College London that deals with the geochronological aspects of the subject. The notes introduce the basic principles of radioactive decay, mass spectrometry and isotope dilution before discussing the most common geochronometers in use today, including radiocarbon, Rb-Sr, Sm-Nd, U-Pb, Pb-Pb, K-Ar, Ar-Ar, U-Th-He, [...]

Isotopic composition (238U/235U) of some commonly used uranium reference materials

Daniel Condon, Noah McLean, Stephen R Noble, Samuel Bowring

Published: 2017-11-05
Subjects: Chemistry, Cosmochemistry, Earth Sciences, Geochemistry, Inorganic Chemistry, Physical Sciences and Mathematics

We have determined 238U/235U ratios for a suite of commonly used natural (CRM 112a, SRM 950a, and HU-1) and synthetic (IRMM 184 and CRM U500) uranium reference materials by thermal ionisation mass-spectrometry (TIMS) using the IRMM 3636 233U–236U double spike to accurately correct for mass fractionation. Total uncertainty on the 238U/235U determinations is estimated to be <0.02% (2σ). These [...]

238U/235U Systematics in Terrestrial Uranium-Bearing Minerals

Joe Hiess, Daniel Condon, Noah McLean, Stephen R Noble

Published: 2017-11-05
Subjects: Chemistry, Cosmochemistry, Earth Sciences, Geochemistry, Inorganic Chemistry, Physical Sciences and Mathematics

The present-day 238U/235U ratio has fundamental implications for uranium-lead geochronology and cosmochronology. A value of 137.88 has previously been considered invariant and has been used without uncertainty to calculate terrestrial mineral ages. We report high-precision 238U/235U measurements for a suite of uranium-bearing minerals from 58 samples representing a diverse range of lithologies. [...]

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