Chemical Geology
Papers 10697
1 page of 1,070 pages (10.7k results)
Abstract The balance of carbon flux in subduction zones is critical to the deep carbon cycle. Carbonate-bearing lithologies are the major carbon carriers transported from Earth's surface into its interior at subduction zones. Recently, a number of studies have showed that carbon can be released from the subducting slab through metamorphic decarbonation and dissolution into C-H-O fluids. However, the evolution of the released C-H-O fluids during subduction-zone metamorphism is ambiguous and poorl...
Abstract A surface complexation model of Se(IV) sorption on biotite with one type of strong sorption sites and two types of weak sorption sites were developed based on experimental data obtained from titration, sorption edge and sorption isotherm experiments. Titration data was collected using a batch-wise manner together with backtitration to calibrate the effect of mineral dissolution in 0.01 M KClO4 background electrolytes from pH 3 to 11 in an inert atmosphere glovebox. Further calibrations ...
1 CitationsSource
Abstract Methoxy groups (OCH3) of plants show specific stable carbon and hydrogen isotope patterns that are used for applications in biogeochemical, atmospheric, paleoclimatic and food research. The method of choice for determining stable hydrogen and carbon isotope values of methoxy groups (δ2HOCH3 and δ13COCH3 values) is the conversion to gaseous iodomethane (CH3I) and subsequent measurement by stable isotope ratio mass spectrometry. However, comparative measurements particularly for stable hy...
Abstract We report stable (δ13Cshell, δ18Oshell) and clumped isotope (Δ47) compositions of modern and last glacial fossil snail shell carbonates from the Luochuan and Weinan sections on the central and southern Chinese Loess Plateau (CLP). Our study reveals that the average Δ47 temperature (T47) of modern snails is consistent with monitored temperatures during the snail growing season at the studied locations and is ~10 °C higher than that of fossil snails from glacial time. Moreover, the averag...
Abstract Unravelling complex microbial activity in modern hydrothermal vents can provide crucial insights into the evolution of ancient life on Earth. It is well established that microorganisms in hydrothermal vents have a significant impact on the cycling of metals and mineral formation. However, the detailed roles played by microorganisms in driving sulfide deposition and cycling of toxic metals, like arsenic (As) and lead (Pb), in high-temperature deep-sea hydrothermal vents remain unknown. T...
Abstract It has been recently demonstrated that both temperature and intracellular/metabolic water are recorded by the PO4 moieties comprising the backbone of DNA in microbial cells as well as in total microbial biomass PO4 (Blake et al., 2016; Li et al., 2016). Temperature and intracellular water composition are reflected in the 18O/16O ratio of PO4 (δ18OP) in DNA (Blake et al., 2016). To determine whether the reported temperature recording by microbial DNA-PO4 could be an artifact of variable ...
Abstract The origin of dolomite has long puzzled geologists. It has recently been documented that sulfate-reducing bacteria (SRB) are capable of catalyzing the formation of protodolomite, a previously proposed precursor of ordered sedimentary dolomite. However, the catalytic mechanism of SRB remains incompletely understood. This experimental study is aimed at probing the effect of capsule extracellular polymeric substances (capsule EPS) from SRB on the crystallization of protodolomite in vivo. T...
Abstract The Reef Deposit is an anomalous Au Cu occurrence in the Paleoproterozoic terranes of northern Wisconsin, better known as host to significant Cu Zn volcanogenic massive sulfide (VMS) deposits. Previous work using lead isotopes and fluid inclusions has identified a protracted development of the mineralization from initial formation as the root zone veins of a VMS deposit during the Penokean orogeny (~1.9–1.8 Ga), with the most recent mineralization/remobilization activity associated with...
Abstract Here we present a new flexible modeling tool for simulating the distribution of tracers in the modern ocean. A Working Environment for Simulating Ocean Movement and Elemental cycling within an Ocean Circulation Inverse Model, the AWESOME OCIM, is a transport matrix model (TMM) which is specifically designed to be easy, accessible, and intuitive, even for scientists without prior modeling experience. The AWESOME OCIM comes with a variety of selectable biogeochemical functions, including ...
We present protocols for high-spatial resolution measurement of oxygen isotope ratios of goethite (α-FeOOH) with the Sensitive High Mass Resolution Ion Microprobe – Stable Isotopes (SHRIMP-SI) and propose a natural sample as a potential goethite reference material (RM) for ion microprobe analysis. We assess the effects of goethite chemical composition, crystallographic orientation, and texture on the accuracy and repeatability of SHRIMP-SI δ¹⁸O (δ¹⁸O_(SIMS)) results. Synthetic goethites evaluate...
Top fields of study