A PRIMARY STUDY OF BIOMARKER COMPOUNDS (STEROIDS TERPENOIDS) FROM LATE CENOZOIC SEDIMENTS IN THE CHAN 3-BORING HOLE OF KUNMING BASIN

In this paper, the biomarker compounds (Steroids and terpenoids) in the extracts from Late Cenozoic sediments in the Chan 3-boring hole are studied by means of GC-MS. The Chan 3-boring hole is located at the eastern margin of Dianchi Lake in Kunming Basin. The Cenozoic sediments in the hole mainly consist of weakly consolidated sands, silts and clays with peat and brown coal seams, up to 516 m thick. The primary study of biomarker compounds shows that the composition, structure and distribution of biomarker compounds in the sediments are obviously different from those in source rocks and crude oils. Higher abundance of 17β(H), 21β (H) hopanes, and 5α(H), 14α (H), 17α (H), 20R-steranes and the presence of a lot of steranes and terpenes in these samples indicate that they are immature. There is no relationship between the characteristics of biomarker compounds in the sediments and the burial depth. This completely reflects the evolutionary level of organic matter in the sediments. But the relative amount of ββ-hopanes in the sediments tends to decrease gradually with increasing of depth, thus it can be considered as a more effective index for thermal evolution. The distributions of carbon number in steranes and terpanes are controlled by the types of the sediments. Relative amounts of C29 steranes and C27 hopanes in the carbonaceous mud and brown coal are larger than those in argillaceous sediments. It is interesting to note that the distributions of carbon number in ααα R-Sterancs series and αααR-Sterenes series are similar.