NEW FINDINGS OF BIODEGRADED NAPHTHIDES IN ROCKS OF THE VENDIAN KHATYSPYT FORMATION OF THE OLENEK UPLIFT

Abstract

The geochemistry of organic matter (OM) and rocks from new sections of the Vendian Khatyspyt Formation on the Olenek uplift has been studied. The analysis of bitumens revealed signs of deep biodegradation of saturated hydrocarbons (HCs), demethylated terpanes in six samples. The present work is aimed at identifying the composition features of the OM components from rocks, containing biodegraded bitumens and assessing the Khatyspyt Formation rocks as potentially source ones. It was found that the rocks are enriched with OM, which accumulated under reducing conditions with possible sulphurous contamination of near–bottom waters, the water column was stratified. Its maturity on the Olenek Uplift corresponds to the initial stages of mesocatagenesis (the early oil window), it could generate naphthides. Comparative molecular analysis of saturated HCs showed that the source of biodegraded bitumens was represented by the dispersed OM of the Khatyspyt Formation. The peculiarities of HCs distribution indicate several stages of primary migration of bitumens. It is assumed that not only potentially oil source rocks can be distributed in the Khatyspyt Formation, but also rocks that are re-enriched with naphthides.