摘要
采用GC TC IRMS技术,测定辽河坳陷西部凹陷和吐哈盆地台北凹陷的陆相烃源岩抽提物中正构烷烃单体的氢同位素组成。结果表明,陆相来源的正构烷烃单体氢同位素组成大致为-250‰～-140‰,明显比海相来源的贫D(2H);不同陆相沉积环境来源的正构烷烃中,咸水湖相的相对富D(-200‰～-140‰),沼泽相的相对贫D(-250‰～-200‰),淡水滨浅湖—湖相的介于其间。从沼泽相→滨浅湖相→咸水湖相,正构烷烃的氢同位素组成明显存在逐渐富D的趋势,表明控制正构烷烃氢同位素组成的主要因素可能是沉积环境,沉积后期水体与有机质之间氢的交换作用可能也是重要影响因素。利用正构烷烃的氢同位素组成对其母源进行古环境的恢复时,需要结合其它方面的证据。
The gas chromatography - thermal conversion - isotope ratio mass spectrometry (GC-TC-IRMS) has been used to measure the hydrogen isotopic compositions of individual lipids in different terrestrial depositional environment: Liaohe Basin and the Turpan Basin, China. The analytical results indicate that the δD values of individual n-alkanes in the extracts of terrestrial source rocks exhibit larger variation, ranging from (-250‰) to (-140‰), and are obviously lighter than those of marine (n-alkanes). Moreover, a trend of depletion in deuterium (D) is observed in individual n-alkanes from different terrestrial depositional environment, from saline lacustrine (δD range from(-200‰) to (-140‰)); swamp (δD range from(-250‰) to ( -200‰)); and freshwater paralic lacustrine – lacustrine environment fall between the values for the former two end members. The shift toward lighter hydrogen isotopic compositions from saltwater to freshwater environment indicates that depositional paleoenvironment is the major controlling factor for the hydrogen isotopic compositions of individual compounds. Hydrogen exchange between formation water and sedimentary organic matter has possibly played an important role in regard to the hydrogen isotopic compositions of individual n-alkanes. Other geochemical evidences would be incorporated into when depositional paleoenvironment of source rocks is reconstructed based on the hydrogen isotopic compositions of individual (n-alkanes).
出处
《石油勘探与开发》
SCIE
EI
CAS
CSCD
北大核心
2004年第1期60-63,共4页
Petroleum Exploration and Development
基金
中国科学院创新项目(kzcx2 110)
中国科学院重大项目(kczx1 sw 18 03)
关键词
陆相有机质
正构烷烃
氢同位素
辽河坳陷
吐哈盆地
terrestrial source rock
n-alkanes
hydrogen isotope
Liaohe Depression
Turpan Basin
