Thermal maturity and depositional environments of organic matter in the post-Variscan succession of the Holy Cross Mountains

摘要: The results of GC-MS investigations biomarkers in organic matter from the epicontinental Permian and Triassic strata Holy Cross Mts. indicate generally suboxic (Permian) oxic (Triassic, except for Middle Muschelkalk) depositional environments with accompanying intensive bacterial reworking remains. biomarker spectra found Muschelkalk Entolium discites Beds (Upper show presence gammacerane, an increased concentration C34 homohopanes a Pr/Ph ratio not exceeding 1. All these observations suggest hypersaline sedimentary environment water column stratification poorly oxygenated conditions. Thermal maturity were based on both vitrinite reflectance indices. succession is slightly more mature along northern margin than their southern part, due probably to regional increase maximum burial depth during Mesozoic. at Galezice (southern Mts.) similar that rocks whereas Kajetanow (in north) characterised by values significantly higher comparable those wells further north. difference cannot be accounted solely differential depths, implies existence positive thermal anomaly active before Triassic. Our confirmed low However, contrary earlier interpretations, we depths reconstructed thickness post-Triassic deposits may account observed levels, assuming geothermal gradients Mesozoic today’s.