Application of biomarker and non-biomarker parameters to assess maturity using the Central Carpathian Paleogene Basin as a case study

Abstract

This study employs an integrated approach to investigate the thermal maturity of sedimentary rocks within the Central Carpathian Paleogene Basin (CCPB) by combining biomarker and non-biomarker parameters. The research primarily applies biomarker ratios based on the distribution of aliphatic and aromatic hydrocarbons and compares them with other paleotemperature indicators such as Rock-Eval pyrolysis. The results reveal a notable thermal gradient across the CCPB. The highest maturity levels are recorded in the Spiš Basin with calculated vitrinite reflectance values exceeding 2.0 %, and the least mature in the Orava Basin and Šariš Upland. The latter two contain unsaturated compounds, indicating immature organic matter. The variations in the paleotemperature pattern emerge from the changing thickness of overlying rocks in these areas. The findings suggest that the calculated vitrinite reflectance derived from the methylphenanthrene index (MPI1) is the most appropriate method for characterizing the broadest maturity range. When comparing the results of the illite/smectite-derived paleotemperatures with biomarker-derived ones, there is a good agreement in the results of the rocks with a higher degree of maturity. In contrast, at lower maturities, the illite/smectite-derived paleotemperatures appear to be overestimated. This study highlights the limitations of using a single maturity indicator and argues for a comprehensive approach combining different parameters to accurately reconstruct paleotemperatures. These results advance our understanding of the geological evolution of the CCPB and provide valuable information for future hydrocarbon exploration in the region. The CCPB is an excellent testing ground for comparing different maturity parameters.