Abstracts of Annual Meeting of the Geochemical Society of Japan

Behavior of LIL elements such as alkalies and alkaline earths will be reported in alkali-feldspars from silicic plutonic rocks such as some granitic plutons having various formation processes, leucosomes accompanied by assimilation and magma mixing, and K-feldspar megacrysts.

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Marbles from Highland complex in Sri Lanka, contained calcite-dolomite-graphite assemblage, where were metamorphosed under ultra-high temperatures. We calibrate these ultra-high temperature assemblages with calcite-dolomite solvus temperature for carbon isotopic geothermometry. Solid inclusions of maganesian calcite in forsterite and spinel in marbles showed a close system in mineralogically and have a possibility of representation of the ultra-high temperature chemical equilibrium. Then these solvus temperatures give us the best opportunity of reservation of the maximum temperatures attained. These sulvus temperatures gave us the high-temperature region of 770-890 °C . We obtained a consistent relationship between empirical carbon isotopic signature (calcite-graphite, dolomite-garphite) and the solvus temperatures of the inclusion.

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Resent results of carbon-dioxides are reported in the terrestrial interior.Carbon-bearing materials are bonded to interior solids by various states due to big differences with hydrogen as these mineral-species and contents.Dynamic experiments of carbon-dioxides absorption to minerals and rocks at higher pressure show that micro-carbonates are synthesized at various states including higher-pressure forms. It suggests that present results indicate wide and long existence of carbon-bearing materials in the terrestrial interiors after terrestrial giant impact to the primordial interior as new idea and experiments.

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Laser ablation combined with quadrupole- or multiple collector-type ICP-MSs has rapidly become one of the most important tools for in situ analyses of elemental and isotopic compositions of a wide variety of geological materials. This technique features direct solid sampling at high spatial resolution, depth profiling ability, and high data throughput. Newest models of laser ablation system prefer short laser wavelength and short pulse width (e.g. femto-second laser) to minimize ablation induced elemental and isotopic fractionation. Quantitative analysis has usually been carried out by external calibration using NIST synthetic glasses (typically SRM 612 and 610) as reference standards and a naturally-occurring major element with known concentration as internal standard to correct for the ablated mass and instrumental drift. However, recent studies demonstrate that this calibration is affected by matrix effects. Calibration against NIST glasses may cause significant inherent bias because of large difference in major compositions between the NIST glasses and most of geological samples. Using a 193 nm argon fluoride (ArF) excimer laser ablation system, we investigated the validation of NIST SRM 612 and USGS glasses (BHVO-2G and BCR-2G) as calibration standards for determination of incompatible trace elements in MPI-DING reference glasses (Jochum et al 2005) and mineral separates of mantle xenoliths.

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