Showing papers in "Geochimica et Cosmochimica Acta in 2021"

TL;DR: In this article, the authors present a comprehensive dataset (N = 272 ) of lacustrine brGDGT distributions, consisting of both new and previously reported samples, spanning a wide range of geographical locations, air temperatures, and lakewater pH values.

TL;DR: In this article, the authors explored how native minerals and organic matter (OM) affect the rate of Fe(II) oxidation and resulting de novo Fe(III) minerals in soil slurries.

TL;DR: This paper investigated brGDGT distributions in contemporary sediments collected from 52 lakes in mid-latitude Asia and found a strong salinity control on the relative abundance of 5-methyl brDGTs versus their late-eluting isomers (including 6-methyl, 7-methyl and unknown isomers).

TL;DR: In this paper, the authors present evidence from 34S/32S isotope ratios in dissolved SO42− (δ34SSO4), together with dissolved major ion concentrations, that reveals FeS2 oxidation throughout the Langtang-Trisuli-Narayani River system of the Nepal Himalaya.

TL;DR: In this paper, the authors used stable potassium (K) isotopes to fingerprint the long-debated crustal signatures in lavas from Martinique Island, Lesser Antilles arc.

TL;DR: In this article, a comprehensive set of concentration measurements and isotopic signatures for acetate and formate, as well as the dissolved inorganic and organic carbon pools, for saline fracture waters naturally flowing 2.4 km below surface in 2.7 billion year-old rocks on the Canadian Shield were reported.

TL;DR: In this paper, an in-situ Sm-Nd and Th-Pb isotopic investigation of monazite and bastnasite from a geologically-complicated deposit, the world-class Bayan Obo REE deposit of China, with the aim of defining the general mechanisms accounting for the protracted age spread observed in this and many other REE deposits.

TL;DR: In this article, the authors applied a combined isotope and doubly-substituted isotopologue (clumped) methane approach to samples collected over a 9-year long-term experiment at the Kidd Creek scientific observatory located 2.4 and 2.9 km below surface.

TL;DR: In this paper, the authors investigated the mechanism of K adsorption on clays (kaolinite and smectite) and the isotopic fractionation in three experimental sets with K-containing solutions.

TL;DR: Flensburg is the only chondrite sample known to have been preserved from aqueous alteration and brecciation as mentioned in this paper, which is the oldest known evidence for breccia and carbonate formation.

TL;DR: In this article, the authors found evidence for rapid marine Cr(III) oxidation linked to microbial Mn(II)-oxidizing bacteria and by natural microbial communities in seawater samples collected from the seasonally lowoxygen zone of the Chesapeake Bay, Maryland, USA.

TL;DR: In this article, the authors review the aqueous alteration history of the CM chondrite group and demonstrate that alteration was prograde, with an early period at low temperatures (<70°C, while later alteration operated at higher temperatures of 100-250°C.

TL;DR: High-precision measurements of the massindependent Cr isotope compositions of chondrites and terrestrial samples are reported using for the first time a multi-collection inductively-coupled-plasma mass-spectrometer to better understand the formation histories and genetic relationships between chondrite parent bodies.

TL;DR: In this article, the authors determine equilibrium Fe isotope fractionation factors between several common rock-forming minerals using a comparative approach involving three independent methods: (i) isotopic analyses of natural minerals from a metapelite from Mt. Moosilauke, New Hampshire, for which equilibration temperature and pressure are well constrained to be near the aluminosilicate triple point (T

TL;DR: In this paper, the authors measured the chemical, including major and trace elements, and mineralogical composition of microbialites from ten Mexican lakes as well as the chemical composition of the surrounding waters.

TL;DR: In this paper, the authors theoretically investigated the main potential driving processes: thermodynamic equilibrium effects driven by either (i) vibrational energy or (ii) nuclear volume, and (iii) diffusion-driven kinetic effects.

TL;DR: In this paper, a combined phase-equilibria and equilibrium mineral-melt isotope fractionation model was proposed to study the role of core-derived and recycled mantle components in generating heavy 57Fe melts.

TL;DR: This article used position-sensitive-detector X-ray diffraction (PSD-XRD), thermogravimetric analysis (TGA) and transmission infrared (IR) spectroscopy to characterise the mineralogy and water contents of 14 heated and ungrouped carbonaceous chondrites.

TL;DR: In this article, the Ba isotope compositions of well-characterized Huili granitic pluton and associated mineral separates from the Jiaobei Terrane in the North China Craton.

TL;DR: The high precision ages from this study indicate that there was potentially more than one chondrule forming event represented in the studied population, and the restricted duration of chond rule formation ages suggests an origin in high density environments that subsequently lead to parent body formation.

TL;DR: In this paper, the authors analyzed the K isotopic composition of 32 river samples from 24 major rivers globally and attributed the dissolved K isotope composition of global rivers to the fraction of K retained in clay minerals during chemical weathering.

TL;DR: In this article, the Δ47 and Δ48 data of carbonates that were previously considered as having crystallized closest to equilibrium in a temperature range of 8 to 1100°C were presented.

TL;DR: In this article, the authors examined how extracellular polymeric substances (EPS) interacted with the ubiquitous soil iron (oxyhydr)oxide ferrihydrite during EPS adsorption and coprecipitation and whether these different EPS-mineral association pathways affect EPS sorption and selective retention, and thus the mobility and fate of microbially-derived OM in the soil environment.

TL;DR: In this article, a multidimensional database of volcanic whole rock compositions and simple petrological models are used to elucidate the controls on volcanic whole-rock compositions with respect to Cu.

TL;DR: In this article, the impact of soil chemical gradients and bacterial community changes (16S rDNA sequence-based) on brGDGT distributions at two grasslands sites (Ossenkampen [NL], ForHot [IS]), and one agricultural site (Craibstone [UK]).

TL;DR: In this paper, the anaerobic oxidation of methane (AOM) is an important methane sink reaction carried out by consortia of methanotrophic archaea (ANME) and partner bacteria in the presence of methane and sulfate.

TL;DR: In this article, the authors analyzed the geochemistry and mineralogy of a 46m-long sediment core drilled into the redox transition zone where a high As Holocene aquifer is juxtaposed to a low As Pleistocene Aquifer in the Red River delta, Vietnam.

TL;DR: In this paper, in situ trace element analysis of apatite in 60 granitoid plutons from the eastern Central Asian Orogenic Belt (CAOB) was performed.

TL;DR: In this paper, a model for the isotope signatures of natural thermogenic methane is proposed, where the non-equilibrium Δ12CH2D2 composition is a signature of the onset of catagenetic methane production.

TL;DR: In this article, the U isotopic composition of open-marine carbonates has been used as a proxy for reconstructing past changes in the redox state of the global ocean, and it has been shown that many Archean and Proterozoic carbonates have unfractionated δ238U values similar to those of continents and riverine runoff.