Showing papers in "Chemical Geology in 2009"

TL;DR: In this article, an analysis of anoxic facies from two North American paleomarine systems, the Late Pennsylvanian Midcontinent Sea (LPMS) and the Late Devonian Seaway (LDS), reveals authigenic Mo-U relationships similar to those of the modern marine environments above, implying similar redox and hydrographic controls.

TL;DR: In this article, the age distribution and petrogenesis of the Gangdese batholith, the largest intrusive exposure along the Transhimalayan magmatic belt, were analyzed for in situ zircon U-Pb and Hf isotopic analyses.

TL;DR: In this paper, the combination of U-Pb and Lu-Hf isotope data obtained by laser ablation-inductive coupled plasma-mass spectrometry provides a powerful tool for distinguishing zircon domains grown during several metamorphic or magmatic events from altered domains affected by complete single or multiple Pb-loss.

TL;DR: The focused ion beam technique (FIB) is an ideal tool for TEM sample preparation that allows for the fabrication of electron-transparent foils with typical dimensions of 15.5 − 1.0 µm, leaving most of the material essentially unaffected by the sampling process.

TL;DR: In this article, an automated method for U-Pb age dating of zircon by single collector laser ablation-magnetic sectorfield-inductively coupled plasma mass spectrometry (LA-SF-ICP-MS) is presented.

TL;DR: In this paper, the IMS-1280 has been used for stable isotope geochemistry applications, and the results show that it can achieve spot-to-spot reproducibility of 0.3 and 2.3 µm.

TL;DR: In this article, a set of four reactive flow-through experiments at temperature T = 100 degrees C and total pressure P = 12 MPa was performed in limestone reservoir samples, with various ranging from 0.7 to 10 MPa, showing non-uniform dissolution features associated with transport-controlled mass transfer, while reaction-controlled uniform dissolution is observed for P-CO2 = 2.5 MPa.

TL;DR: In this article, the authors reported that the Early Cretaceous magmatism in the central Lhasa terrane lasted for a long period (~143-102 Ma) with a magmatic flare-up at ~110 Ma.

TL;DR: In this article, the trace element liberation from metapelites in the range of 2.5-4.5 GPa and 750-1050°C was studied.

TL;DR: In this article, geochemical data for Devonian-mississippian shaly strata (Western Canadian Sedimentary Basin) were used to assess the use of geochemical proxies for thermally mature deposits (>1.5% vitrinite reflectance; VRo), and the ability to apply such proxies to elucidate the paleoceanographic conditions responsible for element distributions.

TL;DR: In this article, the average chemical composition of aeolian dust and varying rates of dust deposition were analyzed and the results suggest some models may underestimate dust deposition rates at the regional and local scales.

TL;DR: In this paper, dissolution rates of calcite, dolomite and magnesite were measured at 25, 60, 100 and 150°C at far from equilibrium conditions in 0.1 M NaCl solutions of pH from 3 to 6.

TL;DR: In this article, the authors classified voluminous granitic intrusions in the West Junggar, NW China, and they can be classified as the dioritic rocks, charnockite and alkali-feldspar granite groups.

TL;DR: In this article, a combination of microscopy, including backscattered imaging, and in situ laser-ablation inductively-coupled plasma mass spectroscopy (LA-ICP-MS) was used to investigate the distribution of invisible gold in As-free pyrite.

TL;DR: In this paper, a quantitative model including an explicit treatment of α-recoil damage, annealing, and their effect on He-diffusion kinetics was developed to test this hypothesis and calibrate it against literature data.

TL;DR: In this article, a study of REE+Y distribution in a variety of Neoproterozoic (Cryogenian and Ediacaran) carbonates from different settings in the Saldania, Gariep, Damara and West Congo Belts in southwestern and central Africa revealed systematic differences that can be explained by varying palaeoenvironmental factors.

TL;DR: In this article, the authors determined the solubility, surface properties (electrophoretic mobilities and surface charge) and dissolution kinetics of phytoliths extracted from fresh biomass of representative plant species (larch tree and elm, horsetail, fern, and four grasses) containing significant amount of biogenic silica.

TL;DR: A review of recent advances in this field, including experimental and theoretical investigations of halogen behaviour in volcanic and related magmatic systems, including halogen abundances in the mantle and magmas on Earth, the effects of halogens on phase equilibria and melt viscosities, their partitioning between melt and fluid phase(s) upon decompression, cooling and crystallisation of magmas in the Earth's crust; and their final atmospheric release as volcanic gases are discussed in this article.

TL;DR: The double spike technique is a well established method for correcting for instrumental mass fractionation in mass spectrometry as mentioned in this paper, and the precision of the technique is controlled by the choices of double spike composition and the proportions in which the double spike and sample are mixed.

TL;DR: A compilation of concordant to near-concordant analyses of a single Phalaborwa baddeleyite crystal yields a precise U-Pb age of 2059 as discussed by the authors.

TL;DR: In this article, the spectral properties of the spectral bands and relative Raman scattering strength of hydrothermally-and cold seep-relevant minerals were determined using laser Raman spectroscopy.

TL;DR: In this paper, a geochemical code incorporating a modified reactive surface model successfully accounted for the passivation effect of secondary calcite layers, which played a major role both as coatings of reactive surfaces and by maintaining large undersaturation with respect to wollastonite dissolution.

TL;DR: In this paper, the dynamics of porosity and reactive surface area changes during porous limestone dissolution by CO2-rich water were explored, and the numerical model HYTEC was used to model the change in reactive surface areas during the experiment.

TL;DR: In this article, the authors present experimental determinations of trace element partitioning between natural fertile lherzolite and near-solidus carbonatitic liquid (CBL) at pressures of 66 and 86 GPa and temperatures between 1265 and 1470°C.

TL;DR: In this article, high precision iron isotope analyses by MC-ICP-MS were performed on a suite of rock samples representative for the volcanic evolution of the Hekla volcano, Iceland.

TL;DR: In this article, multi-episodic (three episodes at least) hydrothermal silica chimneys are identified in the black chert successions in the Ediacaran-Cambrian boundary successions along the southern marginal zone of the Yangtze Platform, South China.

TL;DR: In this paper, reactive transport simulations were conducted to evaluate to what extent and mechanisms through which lead and arsenic might be mobilized by intrusion of CO(sub 2) into a shallow aquifer.

TL;DR: In this paper, the authors analyzed the Ganga River sediments from different depositional regimes in the plain region such as the river channel, active flood-plain and the older flood-plains from the inter-fluve region were analyzed for major, trace and rare earth elements (REEs).

TL;DR: In this article, the authors used laser ablation of perovskite grains collected from the main Mengyin kimberlite sample in northeast China to obtain the age of 470±4 Ma.

TL;DR: In this paper, the main effects of volcanic emissions on atmospheric chemistry are discussed, with a focus on sulphur and halogen compounds, and to a smaller extent on climate, mainly focusing on quiescent degassing, but the main effect of explosive eruptions on the troposphere and stratosphere are covered as well.