Maturation changes of hydrocarbons in solid parts of peloids from Serbian spas – Catalytic influence of clay minerals Scientific paper

Abstract

The study focused on inspecting the composition of n-alkane, sterane and terpane biomarkers in healing mud (peloid) organic matter in the Rusanda, Bujanovac and Vranje spas. It was assumed that the catalytic influence of min­erals on changes in biomarkers could be effectively evaluated based on the dis­tribution of their biolipid and thermodynamically more stable geolipid struc­tural and stereochemical isomers. Quartz, illite, kaolinite, plagioclase, smectite and chlorite were identified in the samples by powder X-ray diffraction. n-Аlk­anes, terpanes and steranes were analyzed in the solid parts of the peloids using the gas chromatography–mass spectrometric, GC–MS, technique. In Rusanda and Bujanovac samples, n-alkanes were identified with distributions character­istic of immature sediments. In contrast, distributions of terpanes and steranes are typical for the mature organic matter of old sedimentary formations. It was concluded that the identified clay minerals do not have an obvious catalytic effect on the maturation of n-alkanes. At the same time, the presence of illite, chlorite, and smectite compensated for all other missing factors (heat, pressure and geological time) by catalytic action and, as a result, gave terpanes and ste­ranes with distributions that are characteristic for petroleum, as the most mat­ure form of organic matter in the geosphere.