The results of a geochemical study of rocks and dispersed organic matter (OM) of the middle member of the Vendian Kharayutekh Formation of the Chekurovka Anticline (Kharaulakh anticlinorium of the Verkhoyansk fold-and-thrust belt) close to the Siberian Platform border are presented. Its rocks are found to be unevenly enriched with OM, the maximum present organic carbon content (Corg) reaches 2.6%. The composition and distribution of chemofossils in saturated and aromatic bitumen fractions were studied using gas chromatography and gas chromatography-mass spectrometry. The distributions of alkanes, steranes, terpanes, dibenzothiophenes, and aromatic steroids as well as light isotopic composition of Corg indicate a bacterial-algal origin of OM. Rocks of the middle member of the Kharayutekh Formation originally possessed a high generative potential. Analysis of pyrograms, bitumen characteristics, and the distributions of phenanthrenes and dibenzothiophenes allowed assessing the regional catagenesis of the OM in Vendian deposits in this area corresponding to the early dry gas «window». It was established that the studied bitumens are classified as residual and bare evidence of autochthonous and paraautochthonous origins, with biodegraded hydrocarbons. The study demonstrates the local effect of magmatism on the content and composition of bitumens in the near-contact zone of the section. Intrusion of a thick diabase sill resulted in depletion of generative potential of these rocks in the upper part of the section already in the Cambrian period. The considered information gives us more grounds to assume that accumulations of highly viscous heavy oils and solid bitumens, genetically related to the OM of the middle member of the Kharayutekh Formation, might be expected in the Vendian and Cambrian carbonate and terrigenous reservoirs in the north of the Verkhoyansk Trough. The preservation of gas and gas condensate accumulations is unlikely to be good.

You do not have access to this content, please speak to your institutional administrator if you feel you should have access.