Maturity effects on steranes of source rocks in Lishu fault depression,Songliao Basin  

作　　者：Chuanjun Yi Min Zhang Li Teng 

机构地区：[1]College of Resources and Environment,Yangtze University,Wuhan,People's Republic of China [2]Key Laboratory of Exploration Technology for Oil and Gas Resource,Ministry of Education,Wuhan,People's Republic of China

出　　处：《Acta Geochimica》2020年第4期561-573,共13页地球化学学报（英文）

基　　金：financially supported by the National Natural Science Foundation of China(Grant No.41772124)。

摘　　要：Geochemical analysis results of 30 source rock samples from Lishu fault depression in Songliao Basin show that samples are compositionally similar and represent a uniform organic facies.Differential distribution of steranes among the samples is due to rank,with vitrinite reflectances(Ro)ranging from 0.65 to 1.61%.In the maturity stage(Ro=0.65-1.20%),the absolute concentrations of steranes increase,which is affected by kerogen degradation,whereas the pyrolysis of high mature source(Ro=1.20-1.61%)show a decrease in the abundance of steranes.Simultaneously,the parameters of steranes vary greatly with maturity.Decrease of prognane/regular sterane value with the increase of maturity suggests that pregnane is not a product of regular steranes pyrolysis.The ratios of C27/C29regular sterane gradually increase,while the value of C29-20S/(20S+20R)and αββ/(αββ+ααα)decrease at high maturity stage,which is associated with the difference in the thermostability of steranes involved.This reversed trend can be used to determine the high-maturity stage of source rocks.Whereas the values of rearranged steranes/regular steranes in source rocks show an apparent positive correlation with maturity,it,therefore,appears to be particularly useful for maturity assessment at elevated levels.

关 键 词：Thermal effect STERANES Genetic mechanism Lacustrine source rocks MATURITY 

分 类 号：P618.13[天文地球—矿床学]