Showing papers in "Chemical Geology in 2017"

TL;DR: In this paper, the authors review the principal biogenic methane-yielding pathways in coal beds and shales and the isotope effects imparted on methane, document the uncertainties and inconsistencies in established isotopic fingerprinting techniques, and identify the knowledge gaps in understanding the subsurface processes that govern H and C isotope signatures of biogenic Methane.

TL;DR: In this article, the authors review recent literature about mechanisms in which carbonate minerals may impact the global carbon cycle, including carbonate mineral dissolution, which increases dissolved inorganic carbon (DIC) concentrations, may represent a net atmospheric CO 2 sink as primary productivity consumes DIC, resulting in organic C burial in fluvial systems of carbonate terrains.

TL;DR: In this paper, the authors provide an overview of the first studies on mass-dependent isotope variations of Mo in igneous rocks and the Mo isotopic characteristics of major geochemical reservoirs before assessing the potential of Mo isotope variation as a new tracer in mantle geochemistry.

TL;DR: In this article, the authors present a comprehensive analysis of a Shuram-associated interval from the uppermost Doushantuo Formation in South China, revealing petrographic evidence of methane-derived authigenic calcite (formed as early diagenetic cements and nodules) that are remarkably depleted in 13C and systematically depleted in 18O relative to cooccurring dolomite.

TL;DR: In this paper, a laser ablation-inductively coupled plasma mass spectrometry (LA-ICPMS) based U-Pb geochronometric method for dating grossular-andradite (grandite) garnet was presented.

TL;DR: In this article, a detailed petrographic and geochemical study of a hypabyssal sample (BK) from the Bultfontein kimberlite (Kimberley, South Africa) is presented.

TL;DR: In this paper, the authors propose a causal link between the activity of phototrophic sulfide oxidizing bacteria, related to the development of photic-zone euxinia, and the hyper-enrichment of Zn in black shales of the Bakken Formation.

TL;DR: In this paper, a global seawater eNd database was updated and combined with hydrography parameters (temperature, salinity, nutrients and oxygen concentrations), carbon isotopic ratio and radiocarbon of dissolved inorganic carbon.

TL;DR: In this article, the effects of reaction temperature on dolomite stoichiometry and cation ordering were evaluated and quantified using hundreds of high-temperature dolombization experiments.

TL;DR: In this article, the most likely routes to forming organophosphate molecules in the context of a plausible prebiotic geochemistry may rely instead on ephemeral phosphate minerals, or redox reactions of phosphorus to form the necessary soluble and reactive phosphorus reagents.

TL;DR: In this article, the authors evaluate the origin of kimberlite magmas and evaluate possible mantle sources of the 655-Ma "diamond-rich" Renard and 629-Ma ‘barren’ Wemindji kimbersites on the eastern Superior craton in Quebec, Canada.

TL;DR: In this article, the authors proposed a statistical treatment of LAFT data on an equal footing with the EDM by formulating four different analytical protocols, depending on the accuracy and reproducibility of the uranium measurements.

TL;DR: In this paper, the authors compile serpentinite geochemical data and report discriminative FME enrichment trends for mid ocean ridge vs. forearc serpentinisation by applying alkali element-U ratios.

TL;DR: In this paper, the authors used MSXRF, X-ray Absorption Near Edge Structure (XANES) and Extended X-Ray Absorptions Fine Structure (EXAFS) to characterize the oxidation states and chemical bonding environment of Ge, As, and W in two world-class Mesozoic Ge-in-lignite deposits (Lincang, Yunnan, southwestern China; Wulantuga, Inner Mongolia, northeastern China).

TL;DR: In this paper, the authors argue that the mechanism of synchronization of magmatism over such a short period of time along such a long distance is the major question which has to be answered in search of the correct model for the origin of the Karoo-Ferrar large igneous province.

TL;DR: In this article, a detailed evaluation of how key parameters of operation influence the measurement of sulfur isotopes using laser ablation multiple collector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS).

TL;DR: Monocle as mentioned in this paper is an interactive interrogation tool for 2D LA-ICP-MS element and isotope maps, which can display histograms and density/probability plots of the element concentration (or ratio, or age) contained within the area under the loupe.

TL;DR: In this article, the stable isotopic composition of zinc in sediment cores, suspended particulate matter (SPM) and rocks collected at the Sepetiba Bay (southeastern Brazil), an estuarine lagoon heavily impacted by metallurgic activities has been tested.

TL;DR: In this article, the authors summarize what is known about the bulk chemistry (major elements) of Martian igneous rocks and use the chemistry to constrain the formation conditions in the interior, and how these conditions have changed through time.

TL;DR: In this article, the authors examine potential causes for variations in the various densimeters and show that these differences are mainly the result of using different Raman instruments and settings, different collection parameters, and different analytical methods.

TL;DR: In this article, the authors investigated the chromium isotope fractionation of the temperate Connecticut River, USA, including Cr concentrations and isotopic compositions of river water, suspended particles, riverbed sediments, and weathering profiles, and found consistent seasonal difference in suspended Cr concentration and δ53Cr.

TL;DR: In this article, the effect of iron content and iron nanolites on Raman spectra of hydrous geologically-relevant glasses was investigated using two spectrometers and the results showed that the area of the band at 3550 cm−1 linearly correlates with the sample water content regardless of chemical composition.

TL;DR: In this article, the authors investigated the dynamics of Fe and organic carbon (OC) in four forest soils in the presence of the dissimilatory Fe-reducing bacterium, Shewanella oneidensis MR-1.

TL;DR: In this article, a modified MAD was constructed for a typical pelitic bulk rock composition, based on the degree of overstepping required to nucleate garnet, aluminosilicate, staurolite, and cordierite.

TL;DR: In this paper, the aquatic geochemistry of CO2, CH4, dissolved organic carbon (DOC), P, Si, and colloidal trace metal from hollows, depressions, permafrost subsidences and soil waters in the actively thawing discontinuous permaure zone of Western Siberia Lowland (WSL).

TL;DR: In this article, a simple PbO-SiO2 system with an increase in lead content from 5 to 70 mol% was analyzed and the results of these analyses have been complemented by spectroscopic studies (Raman & X-ray Absorption Spectroscopy) in order to link macroscopic properties to structural information at short and middle-range order.

TL;DR: The Weondong skarn consists of grandite (andradite-grossular) garnets, which exhibit poikilitic/intergrowth textures and compositional zoning in metasomatism as discussed by the authors.

TL;DR: In this paper, the chemical and boron-isotope compositions of tourmalines from the Panasqueira W-Sn-Cu vein in Portugal have been determined from three settings: pervasive fine-grained tourmalinization zones in wallrocks within 10 cm of the veins, coarser tourmaline in wallrock-hosted fault zones, and needle-shaped tourmalining from late-stage vugs in the quartz veins.

TL;DR: In this article, anomalous Hg levels up to the μg − 1 range were found in sulfide-rich black shale and phosphorite in the lowermost part of the Early Cambrian black shale sequences on the Yangtze Platform in South China.

TL;DR: In this paper, the authors examined the Mg isotopic systematics of 77 bulk marine sediment samples from ten DSDP and ODP drill sites adjacent to the world's major subduction zones to assess their potential to cause mantle heterogeneity.