The Geochemical Characteristics of Carbonand Hydrogen Isotopes of Kerogens of Various Maturity and Depositional Environments
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摘要: 干酪根的碳同位素组成与源岩类型有无相关性存在不同认识,此次研究表明,在陆相沉积条件下,腐泥型干酪根相对富集轻碳同位素12C(δ13C一般小于-28‰),腐殖型干酪根相对富集重碳同位素13C(δ13C一般大于-26‰)。热模拟实验表明,热演化过程对干酪根碳同位素不产生明显影响,但其H/C原子比随热演化程度增高而减小。已有资料对干酪根氢同位素研究较少,本文研究表明,干酪根的氢同位素组成主要与沉积介质的盐度有关。笔作者将干酪根氢同位素组成δD=-130‰作为源岩沉积介质为淡水和咸水一半咸水的界限,前者小于-130‰,后者大小-130‰。Abstract: 40 kerogen samples were collected from 12 regions ( basins) in China. Three of them have been heated for 40 hours at 8 differ-ent temperatures from 250℃ to 700℃.respectively. And 24 heated kerogen samples have been obtained. All these 64 kerogensamples were analysed for their carbon isotopic compositions and 50 of them were analysed for their hydrogen isotopic compositionsA few of the samples were analysed for the C, H, O, N elemental compositions. The carbon isotope compositions of the analysedkerogens range from -23. 0 to -31.2‰(PDB), the hydrogen isotopic compositions of the kerogens range from -94 to-159‰(SMOW ).The research indicated that: 1 .in the terrestrial depositional environments, the carbon isotope composition of kerogenis mainly controlled by the types of kerogen, i. e. the sapropelic type of kerogen has lighter carbon isotope composition (13C<-28.0‰ ) , and the humic type of kerogen has heavier carbon isotope composition ( 13C> -26.0‰) , and the sapropelic-humic or hu-mic-sapropelic types of kerogens have the carbon isotope compositions ranging from -26. 0 to -28. 0‰.2. The effect of the thermalmaturation on the carbon isotope composition of kerogen is not obvious in the oil and gas generation maturation stage. On the con-trary, the H/C atomic ratio of kerogen decreases with the increasing maturity of source rocks. Consequently, in the higher thermalmaturation stage, the carbon isotope composition of kerogen is more effective than the H/C atomic ratio of kerogen to differentiatethe types of kerogens. 3. The hdyrogen isotope composition of kerogen mainly reflects the salinity of the depositional medium inwhich the source rocks were deposited. The kerogens of the source rocks deposited in the fresh water environments have the hydro-gen isotope compositions lighter than-130‰, and the kerogens of the source rocks deposited in the brackish to salt water environ-menu have the hydrogen isotope compositions heavier than-130‰
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Key words:
- kerogen /
- carbon isotope /
- hydrogen isotope /
- maturity /
- depositional environment
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[1] Galimov.E M'13C/12 in kerogen. in kerogen.lasoluble Organic Matter from Sedimentary Rocks(ed, by Durand B.).Editions Technip. Paris.1980, 271~299. [2] 黄第藩，李晋超，张大江.干酩根的类型及其分类参数的有效 性、局限性和相关性.沉积学报，1984.2(3):18~33, [3] 沈平，徐永昌，王先彬等编.气源岩和天然气地球化学特征及 成气机理研究.兰州:甘肃科学技术出版社，1991,101~114, [4] Schidlowski,M A 3800-million-year isotopic record of life from carbon in sedimentary rocks. Nature.1988.333:313~318. [5] Patters K E,B G Rohrback and I R Kaplan. Carbon and hydro- gen Stable isotope variations in keraoen during laboratory-simu- fated thermal maturation. AAPG Bull.I981.65:501~508. [6] Rigby G,B D Batts and J W Smith. The effect of maturation o0 the isotopic composition of fossil fuels. Org. Geochem. 1981 .3:29 ~36. [7] Golyshev S I. Verkhovskaya N A,Burkova V N et al. Stable car- bon isotopes in source-bed organic matter of West and East Siberia. Org Geochem ,1991.14 : 277~ 291 [8] 程克明，关德师，陈建平等.烃源岩产烃潜力的热压模拟实验 及其在油气勘探中的应用.石油勘探与开发，1991,18(5):1~ 11 [9] 范善发，黄健全，周中毅等，准噶尔盆地南缘二叠系油页岩有 效生烃排烃量的实验研究.准噶尔盆地油气地质综合研究. 兰州:甘肃科学技术出版社，1992,21~61 [10] 王少昌.鄂尔多斯盆地上古生界煤成气藏形成条件及预浏. 天然气工业，1988.8(3):15~19 [11] Hoefs 1 and M Frey. The isotopic composition of carbonaceousmatter in a metamorphic profile from Swiss Alps. Geochim. Cos-mochim.Acta,1976,40:945-951. [12] 沈平.王有孝，耿桂元等.煤化作用和成烃机制.中国科学院兰州地质研究所生物、气体地球化学开放研究实验室研究年报(1986).兰州:甘肃科学技术出版社，1987,137-150. [13] Schoell M.，Recent advances in petroleum isotope geochemistry,Org.Geochem.1984,6:645-665. [14] 赵重远.渤海湾盆地的构造格局及其演化.石油学报，1984,5(1):1-8. [15] 包建平，王铁冠，干一女.生物标志物组合与苏北金湖凹陷卑二段(Ef,)沉积环境研究.沉积学报，1991,9(4):136-141. -
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