2,3,6-/2,3,4-Aryl Isoprenoids in Paleocene Crude Oils from Chinese Jianghan Basin: Constrained by Water Column Stratification

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• 作者：Hong Lu ; Chenchen Shen ; Zhirong Zhang ; Ming Liu ; Guoying Sheng ; Ping鈥檃n Peng ; Chang Samuel Hsu
• 刊名：Energy & Fuels
• 出版年：2015
• 出版时间：August 20, 2015
• 年：2015
• 卷：29
• 期：8
• 页码：4690-4700
• 全文大小：714K
• ISSN：1520-5029

文摘

2,3,4-Trimethyl aryl isoprenoid (AIP) hydrocarbons as well as their 2,3,6 homologues were found in most Paleocene crude oils from the Jianghan Basin, China. We interpret their concurrence as evidence for the presence of both purple sulfur bacteria (PSB, family of Chromatiaceae) and green sulfur bacteria (GSB, family of Chlorobiaceae) in the water body during deposition. The GSB and PSB contributions are also evidenced by the presence of the monoaromatic carotenoid derivatives chlorobactane and okenane as well as C₄₀ diaromatic carotenoid derivatives, including isorenieratane and renierapurpurane. The presence of related biomarkers of gammacerane, phytane and methyl trimethyltridecyl chromans (MTTCs) in the oil samples implies that these prolific photosynthetic sulfur bacteria grew in a mesosaline condition, which is consistent with their niches above and below the oxic鈥揳noxic chemocline in a stratified water column. Thus, the general presence of 2,3,6-AIPs, chlorobactane, and isorenieratane sourced from GSB is consistent with sulfidic (euxinic) conditions in the photic zone of the water column, while their concurrence with 2,3,4-AIPs and okenane further indicates a permanent stratified water column with sulfidic (euxinic) conditions. In such a paleowater-column redox state with ideal growing conditions for the photosynthetic bacteria, PSB likely lived beneath the GSB layer and/or co-existed in the same layer with a symbiotic relationship and/or even as a 鈥?i>Chlorochromatium鈥?aggregate with an endosymbiont relationship. This ecosystem model helps further explain the concurrence of similar amounts of 2,3,6- and 2,3,4-AIPs in the Jianghan Basin oils.