Controls on the Abundance of Carbon Species in Unsedimented Submarine Hydrothermal Systems: An Experimental Investigation

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ABSTRACTOCE-0136954As more is discovered of the extent and nature of the large scale venting and circulation of hydrothermal waters through the oceanic crust, delineation of abiotic chemistries from subsurface biogeochemical cycles has become increasingly blurred in some senses, yet clearly intertwined in others. Consideration of the chemistry of organic compounds in aqueous hydrothermal fluids currently poses many uncertainties and intriguing questions. The deliberately constrained laboratory experimental approach of this study will use flexible-cell hydrothermal vessels to investigate a number of key chemical objectives: i) measurement of calcite solubility at temperatures and pressures appropriate to the conditions experienced during the hydrothermal alteration of oceanic basalts, ii) determination the mineral catalyzed rates of abiotic reduction of CO2 to CH4 and iii) evaluation of the influence of the thermodynamic activity of water on the effectiveness of catalytically active minerals on the abiotic formation of reduced carbon compounds.Interpretation of the results of these investigations has impact upon topics as seemingly diverse as the mid-ocean ridge carbon cycle, the geological sequestration of excess carbon dioxide, the existence of life in extreme environments and even its origin.