The origin and geochemical significance
of the rearranged hopanes
in hydrocarbon source rocks or crude oil have attracted extensive
attention. Despite numerous studies, there is not yet a proper conclusion.
Therefore, this paper discusses the formation conditions of such compounds
and points out their geochemical significance in more detail using
a remarkably broad range of source rocks and crude oils from four
basins in China. Varying content of rearranged hopanes was found in
a total of 19 source rocks and oils from the Ordos, Sichuan, and Tarim
basins and the North China Block. Gas chromatography–mass spectrometry
(GC–MS) in combination with X-ray diffraction (XRD) and conventional
geochemical parameters was used for Pearson correlation analysis to
reveal the enrichment mechanisms of rearranged hopanes in the studied
rock and oil samples. The GC–MS and XRD results showed that
the studied source rocks with high rearranged hopane contents are
closely associated with the high abundance of quartz rather than that
of clay. Furthermore, the present study reveals that anoxic lacustrine
conditions are the primary controlling factors of relatively high
abundance of rearranged hopanes in the studied rocks and oils, whereas
thermal maturity and terrigenous organic matter input are the secondary
factors.