C1-C11 HYDROCARBONS OF HOT SPRINGS. QUANTITATIVE VARIATIONS AND MODES OF GENERATION

Abstract

Geothermal oil, found in rift zones, is an indicator of vigorous geochemical, geological and biological alteration of matter. Appearances of petroleum hydrocarbons have been detected in areas of hot (315°C) brines springs in the Guaymas Basin (Gulf of California). In this paper the authors discuss some possible modes of thermal synthesis of hydrocarbon compounds in both deep and near-surface intervals of hot spring systems, but without detailed consideration of the effects of the hydrochemical or mineralogical environments. The latter have a strong effect on the final composition and chemical structure of the product hydrocarbons whether they are linear or branched, or alkanes, naphthenes or aromatics. Based on experimental data and field observations, they draw the preliminary conclusion that in high-temperature hydrothermal systems the alteration of organic matter and the generation of C1-C11 hydrocarbons is closely associated with pyrolysis at 1000 ± 200°C, as well as with reactions at 300 ± 100°C that duplicate the conditions of laboratory thermolysis and thermocatalysis.