マントルに由来する岩石にともなう高分子炭化水素 [in Japanese] Heavy hydrocarbons associated with mantle derived rocks [in Japanese]
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In order to examine the presence of abiogenic hydrocarbons in igneous rocks, various rock types on the earth were collected and analyzed. The result shows that tectonites in ophiolites and mantle xenoliths in alkali basalts usually contain heavy hydrocarbons. The chromatogram pattern of the heavy hydrocarbons essentially resembles that of crude oils. The heavy hydrocarbons could be contaminated after the rocks raised to the earth surface. Nevertheless, several lines of evidence such as the geological occurrence, the origin of rocks and the carbon isotope data rule out the possibility of the contamination; the detected hydrocarbons must be inherent in iguneous rocks. Three possibilities may be assigned to the origins of the heavy hydrocarbons disclosed by this study. The first is that they have been inorganically synthesized in the mantle. The second is that they are recycled materials biologically produced on the earth. The third is that they are remnants of primordial materials delivered by meteorites and comets in the earth. It is nearly impossible to decide at the present time which of these three hypotheses is the closest to the real origin. The heavy hydrocarbons, however, must provide us important information on the carbon geodynamic cycle.
Chikyukagaku 27(2), 119-134, 1993
The Geochemical Society of Japan