Mantle carbonates

Trull, T., Nadeau, S., Pineau, F., Polve, M., Javoy, M. (1993) C-He systematics in hotspot xenoliths Implications for mantle carbon contents and carbon recycling. Earth Planet. Sci. Lett., 118, 43-64. 

Ionov D. A., Dupuy C., O Reilly S., Kopylova M. G., and Genshaft Y. S. (1993b) Carbonated peridotite xenoliths from Spitsbergen implications for trace element signature of mantle carbonate metasomatism. Earth. Planet. Sci. Lett. 119, 283 -297. 

Pal yanov Y. N., Sokol A. G., Borzdov Y. M., Khokhryakow A. F., and Sobolev N. V. (1999a) Diamond formation from mantle carbonate fluids. Nature 400, 417-418. 

The isotopic fractionation in carbonates mirrors the relative amount of organic carbon buried. It is generally assumed that the source carbon, from vulcanism (the so-called mantle carbon) has an isotopic value of approximately 5%c. As mass balance must constrain the isotopic signatures of carbonate carbon and organic carbon with the mantle carbon, then... 

Deines P. (1992) Mantle carbon concentration, mode of occurrence, and isotopic composition. In Early Organic Evolution Implications for Mineral and Energy Resources (eds. M. Schidlowski, S. Golubic, M. M. Kimberley, D. M. McKirdy, and P. A. Trudinger). Springer, Berlin, pp. 133-146. 

Wheeler, A.P., 1975. Oyster mantle carbonic anhydrase Evidence for plasma membrane-bound activity and for a role in bicarbonate transport. Ph.D. Thesis. Duke University, Durham, NC, 212 pp. 

Consequently, a series of experiments were conducted to measure the rate of XAs3+ oxidation by dissolved O 2 as a function of pH at 25° and 90°C. Experiments were conducted in 1.0-liter glass kettles, and temperatures were controlled to 1°C with heating mantles. Carbon dioxide-free air was continuously bubbled through the solutions to maintain PO2 = 0.2 atm. The initial XAs3 + concentration was 10-4-0 M, and the background electrolyte was 10-2.0 M NaCl in all experiments. To measure rates, samples were removed periodically from the kettles and total As and XAs concentrations were determined by the molybdate-blue method of Johnson and Pilson (28). The concentrations of XAs3+ were determined by diffaence. 

The vast majority of carbon is found in sedimentary rocks as inorganic carbonate minerals and solid organic compounds, and in the deep interior as carbon dioxide and methane. The global carbon cycle can therefore be envisioned as the long-term transfer of deep crustal and mantle carbon to shallow crustal sediment reservoirs via the ocean/atmosphere system, where carbon is parsed into several reservoirs through reactive pathways that modify the initial carbon isotopic value of the outgassed carbon. The... 

Trail TW, Nadeau S, Pineau F, Polve M, Javoy M (1993) C-He systematies in hotspot xenoliths implications for mantle carbon contents and carbon recycling. Earth Planet Sci Lett 118 43-64 Turcotte DL, Schubert G (1988) Tectonic implications of radiogenic noble gases in planetary atmospheres. Icarus 74 36-46... 

The He/C02 ratio (and its inverse) may be used as an indicator of the proportion of mantle carbon in these gases. Marty and Zimmermann (1999) reported He/C02 ratios of (0.7 0.2) X 10 (corrected for the effects of air-contamination and potential fractional degassing) for N-MORB samples. Nishio et al. (1999) reported He/C02 ratios of (3.5 1) X 10 for Rodrigues Triple Junction Indian Ocean MORB and suggested that this higher value reflected pristine mantle whereas lower ratios for MORB indicate carbon... 

Natural occurrence. Carbon monoxide is produced during the incomplete combustion of carbon and carbon-containing compounds, hence it occurs in the exhaust of internal-combustion engines, in coal stoves, furnaces, and gas appliances functioning with an oxygen deficiency. Carbon monoxide is also naturally present in the atmosphere, chiefly as a product of volcanic activity. It occurs dissolved in molten volcanic rock at high pressures in the Earth s mantle. Carbon monoxide contents of volcanic gases vary from less than 1000 ppm vol. to as much as 2 vol.%. It also occurs naturally in bushfires. 

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