ABSTRACT
The organic matter
distribution and hydrocarbon generation potential as well as element
distribution in the lacustrine mudstones of lower Member 3 of Paleogene
Shahejie Formation in the Dongying depression, eastern China were investigated
using methods of Rock-Eval pyrolysis, inductively coupled plasma emission
spectrometer. The results show that most of the samples are high-quality source
rocks with high TOC and S2,
and the oil shale samples are excellent source rocks with the TOC and S2 greater than 5.0% and 20.0 mg/g,
respectively. A freshwater depositional environment
in the deep lake for the mudstones was indicated by lower values of biomarker ratios gammacerane/C30 Hopane and C35Hopane/C34 Hopane. With the lacustrine
regression, the ratios Ca/U, Ca/Ba, Ca/Mg, Ca/B, Ca/Li, Ca/Sr and Sr/Ba
decrease, while Fe/(Ca + Mg) increases. In the section 3330 - 3370 m with
enrichment of oil shale, the organic matter and inorganic elements present
strong fluctuation. The quantitative relations among U, U/Th and TOC, S2, %Ca are divided
into two parts at boundary values of 7.0%, 32 mg/g and 11% for TOC, S2 and %Ca, respectively.