The distribution and origin of dimethyldibenzothiophenes in sediment extracts from the Liaohe Basin, East China

摘要: Abstract The distributions of dimethyldibenzothiophenes (DMDBTs), the relationship between DMDBTs and dimethylbiphenyls (DMBPs), applications as maturity indicators in source rocks have been investigated a set 21 lacustrine shales from Eocene Shahejie Formation (Well SG1) Western Depression, Liaohe Basin, China. All rock samples are characterized by total organic carbon contents 1.37–3.27% Type II (with minor III) kerogen. They were deposited suboxic brackish environments maturities ranging immature to mid-mature. 3,3′-DMBP isomer can potentially react yield 4,6-DMDBT; 2,6-DMDBT 2,8-DMDBT incorporating sulfur into biphenyl, which may be supported strong positive correlation absolute concentration changes those 4,6-DMDBT, plus 2,8-DMDBT. relative abundance DMDBT isomers explained radical mechanism also controlled steric hindrance thermodynamic stability. 4,6-/(1,4- + 1,6)-DMDBT ratio shows no regular trend with increasing at low stage, it should used caution indicator for sediments. However, within oil generation window, 4,6-DMDBT progressively increases maturity, its higher stability 1,4-DMDBT isomer. exhibits linear increase thermal Thus, this applied an effective window.