摘要
对 5个广东泥炭样品和 3个准噶尔盆地西北缘原油样品中支链烷烃和环烷烃进行了分离 ,应用色谱 -同位素比值质谱 (GC -IRMS)测定了其中藿烷类单体碳稳定同位素比值 ,研究它们的碳同位素组成变化 ,结果表明泥炭中藿烷类δ1 3C为 - 2 1 .7‰～ - 34.4‰ ,与湖相页岩和原油中藿类相比 ,相对富集1 3C ;同一样品中 ,不同碳数和不同构型的藿烷之间 ,δ1 3C相差 4.4‰～ 1 2 .8‰ ,说明同一沉积环境中可能生长具有不同碳同位素组成藿类先质的多种微生物 ,相对亏损1 3C的C2 9βα、C2 9ββ、C31 βα藿烷可能来自甲烷菌 ,相对富集1 3C的C2 9αβ、C30 αβ藿烷可能来自化学自养型细菌 ;准噶尔盆地原油中藿烷类碳同位素δ1 3C为 - 30 .6‰～ - 53.4‰ ,原油之间藿烷δ1 3C值具有明显差别 ,它们指示克乌断裂带东部原油来自二叠系 。
The combined gas chromatograph-isotope ratio mass spectrometry(GC-IRMS) was employed to measure compound-specific isotope ratio of hopanes in five peat samples from Guangdong province and 3 oil samples from northwestern margin of Junggar basin. It is shown from the result that the isotopic ratio of carbon for hopanes in peats are -21.7‰～-34.4‰,which are relatively enriched in 13 C compared to that of the lacustrine Messel shale, Green River shale and the oils of Junggar basin, indicating that biological bacteria sourced hopanes of peats are different from that of lacustrine shales and oils. It is also found from the result that the hopanes with different carbon number and configuration in peat XLI have significant difference in isotopic composition of carbon, e.g. the δ 13 C values of C 27 β hopane is -23.2‰,whereas the δ 13 C value of C 29 ββ hopanes is -34.4‰. This demonstrates that various biological bacteria sourced hopanes may be present in the same depositional environment. As C 29 βα, C 29 ββ, C 31 βα hopanes found in peats are isotopically lighter than that of their C 29 αβ, C 30 αβ counterparts, it is suggested that C 29 βα, C 29 ββ, C 31 βα hopanes are sourced from methanotrophic bacteria and that C 29 αβ, C 30 αβ hopans are sourced from chemoautotrophic bacteria. The aim to measure carbon isotopic composition of hopanes in oils of the northwestern margin, Junggar basin in this study is to explore δ 13 C values of hopanes for oils correlation because that the oils are produ ced from various strata in the northwestern margin area and that the strata are devel oped with many faults. As a result, it was found that δ 13 C values of oils from the west of northwestern margin area are quit different from that of the east of northwestern margin, i.e. δ 13 C value of hopanes for oils in the west of northwestern margin are -39.9‰～-53.4‰, whereas δ 13 C values of hopanes for oils in the east of northwestern margin are -33.1‰～-31‰.Since isotopic ratio of hopanes may be enriched in 13 C with increase of their thermal maturation, it is suggested from this study that the age of rock sourced oils in the east of northwestern margin should be older than that sourced oils in the west of northwestern margin, i.e. the oils from the east of northwestern margin may be sourced from Permian , whereas oils from the west of northwestern margin may be sourced from Triassic and Jurassic.
出处
《沉积学报》
CAS
CSCD
北大核心
2000年第2期310-313,318,共4页
Acta Sedimentologica Sinica
基金
国家自然科学基金资助项目! (批准号 :4 94 72 1 1 2 )
