Biomarker geochemistry of Eq3(4)-10 cyclothem shale in Qianjiang Depression of the Jianghan salt lake facies Basin

摘要

The objective of this study is to provide biomarker geochemistry information on shale between sheet-like salts from Qianjiang Depression of the Jianghan salt lake facies Basin, and illustrate the depositional conditions, source organic matter input and maturation. 7 shale samples from Eq3(4)-10 rhythmic were analysed with gas chromatography-mass spectrometry. The investigated biomarkers show that the shale oil are charactertized by an apperent odd-even preference of n-alkane, low Pr/Ph values and a high content of gammacerane and C-30 + hopanes, maderate C21-/C21+ ratios, the high relative content of C-27 5 alpha(H), 14 alpha(H), 17 alpha(H)- steranes (20R), and an anomaly high C-29 sterane beta beta/(beta beta + alpha alpha) value. These biomarker geochemistry characterizations suggested that the shale oils were derived from mixed aquatic organisms and land plants, and deposited in an anoxic and saline-hypersaline depositional environment.