Abstract:The Kara ore node is located within the Sretensk-Kara ore region of East Transbaikalia. The geological structure of this area is complex due to its location within the Mongol-Okhotsk suture, the zone wherein the Siberian and Mongolia-China continents collided into each other at the turn of the Early and Middle Jurassic. During the plate collision, intense magmatism was accompanied by the formation of focal-dome, dome-ring and other structures. The Kara ore node is controlled by the Ust-Kara focal dome-ring structure. The central part of latter is composed of KaraChacha granitoids from the Amudzhikan-Sretensk intrusive complex (J3-K1) with the system of subvolcanic and vein formations, including grorudites. It is suggested that gold mineralization in the study area is genetically related to grorudites; however, physical and chemical conditions for the formation of these alkaline rocks, their genesis and role in the hydrothermal gold-ore process still have not been sufficiently investigated. To this end, the authors of this paper have studied fluid inclusions (FI) in quartz from these rocks. It has been found that quartz porphyry phenocrysts in grorudite contain FI of diverse forms, the size of which ranges from 5 to 48 microns. Measured temperatures of ice melting (-2.5°C) and complete homogenization into liquid (350 °C) show that the concentration of salts in the fluid amounts to 4.2 wt % of eq. NaC, its density is 0.64 g/cm 3 , and the pressure is 1.6 kb. At LA-ICP-MS of individual FI, clear analytical signals were derived from Na and K. As, Mo, Sb, Cs, W, and Hg were traced in significant quantities. The Raman scanning showed the presence of N2 in the primary (substantially gaseous) FI, and CO2, N2, and CH4 in the primary-secondary FI.

We present new reference values for nineteen USGS, GSJ and GIT-IWG rock reference materials that belong to the most accessed samples of the GeoReM database. The determination of the reference values and their uncertainties at the 95% confidence level follows as closely as possible ISO guidelines and the Certification Protocol of the International Association of Geoanalysts. We used analytical data obtained by the state-of-the-art techniques published mainly in the last 20 years and available in GeoReM. The data are grouped into four categories of different levels of metrological confidence, starting with isotope dilution mass spectrometry as a primary method. Data quality was checked by careful investigation of analytical procedures and by the application of the Horwitz function. As a result, we assign a new and more reliable set of reference values and respective uncertainties for major, minor and a large group of trace elements of the nineteen investigated rock reference materials

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This paper contains the results of an extensive isotopic study of United States Geological Survey GSD‐1G and MPI‐DING reference glasses. Thirteen different laboratories were involved using high‐precision bulk (TIMS, MC‐ICP‐MS) and microanalytical (LA‐MC‐ICP‐MS, LA‐ICP‐MS) techniques. Detailed studies were performed to demonstrate the large‐scale and small‐scale homogeneity of the reference glasses. Together with previously published isotopic data from ten other laboratories, preliminary reference and information values as well as their uncertainties at the 95% confidence level were determined for H, O, Li, B, Si, Ca, Sr, Nd, Hf, Pb, Th and U isotopes using the recommendations of the International Association of Geoanalysts for certification of reference materials. Our results indicate that GSD‐1G and the MPI‐DING glasses are suitable reference materials for microanalytical and bulk analytical purposes.

Stable carbon and nitrogen isotope ratios of collagen from bone and dentin have frequently been used for dietary reconstruction, but this method is limited by protein preservation. Isotopes of the trace element zinc (Zn) in bioapatite constitute a promising proxy to infer dietary information from extant and extinct vertebrates. The66Zn/64Zn ratio (expressed as δ66Zn value) shows an enrichment of the heavy isotope in mammals along each trophic step. However, preservation of diet-related δ66Zn values in fossil teeth has not been assessed yet. Here, we analyzed enamel of fossil teeth from the Late Pleistocene (38.4–13.5 ka) mammalian assemblage of the Tam Hay Marklot (THM) cave in northeastern Laos, to reconstruct the food web and assess the preservation of original δ66Zn values. Distinct enamel δ66Zn values of the fossil taxa (δ66Zncarnivore< δ66Znomnivore< δ66Znherbivore) according to their expected feeding habits were observed, with a trophic carnivore-herbivore spacing of +0.60‰ and omnivores having intermediate values. Zn and trace element concentration profiles similar to those of modern teeth also indicate minimal impact of diagenesis on the enamel. While further work is needed to explore preservation for settings with different taphonomic conditions, the diet-related δ66Zn values in fossil enamel from THM cave suggest an excellent long-term preservation potential, even under tropical conditions that are well known to be adverse for collagen preservation. Zinc isotopes could thus provide a new tool to assess the diet of fossil hominins and associated fauna, as well as trophic relationships in past food webs.

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X-ray diffraction data modeling. Powder diffraction patterns were modeled using a small, anorthic unit cell derived from a LP search (TOPAS Academic V4.1). Figure S1 shows the x-ray powder diffraction data of the synthesized Cu2-δSe with the corresponding Pawley fit. A triclinic unit cell with a = 7.082(8) Å, b = 4.121(3) Å, c = 7.121(3) Å, α = 106.1(0), β = 99.1(0)° and γ = 90.1(4)° has been utilized for the fits in order to determine lattice parameters for each composition.

LA‐ICP‐MS is one of the most promising techniques for in situ analysis of geological and environmental samples. However, there are some limitations with respect to measurement accuracy, in particular for volatile and siderophile/chalcophile elements, when using non‐matrix‐matched calibration. We therefore investigated matrix‐related effects with a new 200 nm femtosecond (fs) laser ablation system (NWRFemto200) using reference materials with different matrices and spot sizes from 10 to 55 μm. We also performed similar experiments with two nanosecond (ns) lasers, a 193 nm excimer (ESI NWR 193) and a 213 nm Nd:YAG (NWR UP‐213) laser. The ion intensity of the 200 nm fs laser ablation was much lower than that of the 213 nm Nd:YAG laser, because the ablation rate was a factor of about 30 lower. Our experiments did not show significant matrix dependency with the 200 nm fs laser. Therefore, a non‐matrix‐matched calibration for the multi‐element analysis of quite different matrices could be performed. This is demonstrated with analytical results from twenty‐two international synthetic silicate glass, geological glass, mineral, phosphate and carbonate reference materials. Calibration was performed with the certified NIST SRM 610 glass, exclusively. Within overall analytical uncertainties, the 200 nm fs LA‐ICP‐MS data agreed with available reference values.