Home – Home – Jornals – Russian Geology and Geophysics 2018 number Неопубликованное

The results of a geochemical study of the Middle Member of the Vendian Kharayutekh Formation rocks and dispersed organic matter (OM) on the Chekurovka Anticline (Kharaulakh Anticlinorium of the Verkhoyansk Fold—Nappe Belt) are presented. Its rocks are established to be unevenly enriched with OM, the maximum modern organic carbon content (C_org) reaches 2.6%. The composition and distribution of chemofossils in saturated and aromatic bitumen fractions were studied using GC and GC—MS. Alkanes, steranes and terpanes, dibenzothiophenes and aromatic steroids distributions as well as light isotopic composition of C_org indicate the bacterial-algal origin of the OM; the rocks of the Middle Kharayutekh Member had the high initial generative potential. The analysis of pyrograms, bitumen characteristics, distribution of phenanthrenes and dibenzothiophenes allowed to estimate the regional catagenesis of the Vendian OM on this territory corresponds to the dry gas window. Studied bitumens are revealed to be residual autochthonous and paraautochthonous with biodegraded hydrocarbons. The local influence of magmatism on the content and composition of bitumens in the contact zone of the studied section is shown. The thick diabase sill intrusion led to the source rock generative potential exhausting in the upper part of the section already in Cambrian. The considered information gives reason to assume that accumulations of highly viscous heavy oils and solid bitumens, genetically related to the Middle Kharayutekh Formation OM might be expected in the Vendian and Cambrian carbonate and terrigenous reservoirs in the north of the Pre-Verkhoyansk Trough. The preservation of gas and condensate deposits is unlikely.