TRANSFORMATION OF TERRESTRIAL ORGANIC MATTER DURING MESOCATAGENESIS AND APOCATAGENESIS
A.E. Kontorovich1,2, K.V. Dolzhenko1,2, A.N. Fomin1,2
1Trofimuk Institute of Petroleum Geology and Geophysics, Siberian Branch of the Russian Academy of Sciences, prosp. Akademika Koptyuga 3, Novosibirsk, 630090, Russia
2Novosibirsk State University, ul. Pirogova 1, Novosibirsk, 630090, Russia
Keywords: Vilyui hemisyneclise, upper Paleozoic deposits, terrestrial organic matter, pyrolysis, hydrocarbon type composition, biomarker hydrocarbons, catagenesis
Abstract
A combination of modern analytical methods was used to study terrestrial organic matter from upper Paleozoic rocks in the central part of the Vulyui hemisyneclise (East Siberia), sampled from the depth interval 3370-6458 m penetrated by the Srednevilyuiskaya-27 superdeep well. In this study we used 71 core samples to trace depth variations in the geochemical characteristics of organic matter during middle-late mesocatagenesis and apocatagenesis: organic-carbon content (Corg), Rock-Eval pyrolysis parameters (HI, Т max), carbon isotope composition, thermal maturity ( R oVt, %), hydrocarbon type composition (hydrocarbons, resins, and asphaltenes), distributions of n -alkanes (TIC), steranes ( m / z 217), and terpanes ( m / z 191), and standard biomarker indices with increasing degree of thermal maturity. It is shown that during late mesocatagenesis and apocatagenesis, the pyrolysis parameters and biomarker indicators are no longer effective as indicators of organic-matter maturity and genesis.
DOI: 10.15372/RGG2020116
|
