Distribution and isotopic signature of 2-alkyl-1,3,4-trimethylbenzenes in the Lower Paleozoic source rocks and oils of Tarim Basin: Implications for the oil-source correlation

• DOI: 10.1016/j.petsci.2022.07.014
• Publication Date: 2022-08-03T01:39:24Z
• Authors: Tao-Hua He; Wen-Hao Li; Shuang-Fang Lu; Er-Qiang Yang; Tao-Tao Jing; Jun-Feng Ying; Peng-Fei Zhu; Xiu-Zhe Wang; Wen-Qing Pan; Zhong-Hong Chen
• Keywords: Tarim basin; Diamondoid; Sterane

Series of 2-alkyl-1,3,4-trimethylbenzenes (ATMBs) were detected in most crude oils and source rocks collected from various strata locations the Tarim Basin. They appeared to have heavy carbon isotopic signatures (δ13C, up ∼ −16‰) compared those hydrocarbons oxygenic phototrophic organisms, indicating that unequivocal green sulfur bacteria (GSB) photic zone euxinia (PZE) existed original environment. Considering high paleoproductivity, PZE may enhanced preservation organic matter, which triggered formation extremely organic-rich with TOC 29.8% for Lower Cambrian Yuertus Formation (Є1y). The coexistence ATMBs diagnostic products secondary alterations (e.g., abundant 25-norhopanes, thiadiamondoids, diamondoids) indicated a stronger ability anti-second-alterations. Combined results quantitatively de-convoluting mixed oil, oil-source correlation based on large number Paleozoic samples Basin suggested deep oil resources contained dominant contribution (>50%) Є1y rocks. Therefore, ATMBs, as biomarkers precursors under special habitat conditions, might provide important insights exploration