干旱气候变化与可持续发展

近代盐湖沉积物中的生物标志化合物

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  • 中国科学院兰州地质研究所  兰州  730000
范璞

收稿日期: 1994-01-12

  网络出版日期: 1994-05-01

BIOMARKERS FROM RECENT SALT-LAKE SEDIMENTS

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  • Lanzhou Institute of Geology, Academia Sinica, Lanzhou  730000

Received date: 1994-01-12

  Online published: 1994-05-01

摘要

    生物标志化合物是在沉积有机质地质演化过程中可保留其原碳骨架的生物分子,具记录沉积环境和沉积有机质热演化历史的功能。用有机地球化学方法(气相色谱、气相色谱/质谱、热解色谱和同位素质谱)对采自我国西部盐湖的近代沉积物进行了大量研究,而且对盐湖沉积环境地球化学特征、有机质组成与早期成岩作用的关系和各种生物标志化合物指标进行了更加深入细致的探索。研究结果表明干酪根碳同位素组成(δ13C PDB)和盐湖类型有关系,例如,硫酸盐型湖的干酪根δ13C 值较重,而碳酸盐型盐湖的δ13C值则较轻。姥鲛烷/植烷比(Pr/Ph)、总三环萜烷/总萜烷(%)、孕甾烷/甾烷比(%)、伽玛蜡烷/αβ—藿烷和三芴系列化合物组成三角图等生物标志化合物指标可以用来判识沉积环境的盐度。通常,在盐湖或咸水沉积环境中,除额吉卓尔盐湖样品因采自边缘,Pr/Ph比值较大而外,其余各盐湖样品的Pr/Ph比值一般≤1.0,而其余各比值均明显大于在淡水湖中的比值;三芴系列化合物三角图中,各盐湖样品均集中分布在硫芴含量高的区域。与我国各典型沉积环境中的原油及古代岩样的分析结果作了对比,发现同样表现出上述规律,故认为是良好的识别标志。正构烷烃分布、甾烷相对含量及某些特殊生物标志化合物的含量如三环二萜烷可以用来划分可溶有机质类型。察汉卓和查干诺尔盐湖可溶有机质中,正烷烃以低碳数占优势,显示其组成主要来源于低等水生生物;额吉卓尔盐湖则以高碳数为主,显然与边缘相陆生高等植物的输入有关;而小柴旦盐湖正烷烃高低碳数分布均衡,说明高等植物与低等水生生物同时输入。C27~C29正常甾烷及三环二萜烷的组成与分布也显示了相似特征。
    另外,还发现了多种非常规生物标志化合物,报导了其 m/z 217、m/z 231、m/z 245、m/z 259离子色谱特征。这些特征离子大多由三芳甾烷产生。三芳甾烷是由生物分子(甾体)在地质条件下演化而成的。盐湖沉积物中大量该类化合物的发现意味着含盐沉积环境及其继后的早期成岩作用在甾体的这种芳化过程中起着积极作用。

本文引用格式

范璞,张柏生,于心科 . 近代盐湖沉积物中的生物标志化合物[J]. 地球科学进展, 1994 , 9(3) : 6 -17 . DOI: 10.11867/j.issn.1001-8166.1994.03.0006

Abstract

Organic matter and biomarkers from many recent salt-lake sediments in West China Have been investigated in the present paper by gas chromatography(GC), gas chromatography-mass spectrometry(GC/MS) multiple ion detection, Pyrolysis and isotope mass spectrometry. Particular emphasis has been placed on the geochemical characteristics of the saline sedimentary environment,the nature of organie matter and the early diagenesis on the basis of the general geochemistry characteristics of organic matter and compositions, distributions and molecular Parameters of various biomarkers. The results show that the carbon isotope composition(δ13C) in kerogen seems to have a certain relation ship with the salt-type of salt lakes; pristane/phytane(Pr/Ph) ratio, ∑tricyclic terpanes/∑terpanes(%), ∑pregnanes/∑steranes(%), gammacerane/αβ-hopane and the relative percentage of three fluorine series eompounds could be regarded as good indicators recognizing sedimentary environments of different salinities; the distribution of n-alkanes, the relative concentration of C27, C28 and C29 steranes and the occurrence of some typical biomarkers such as tricyclic diterpane can be used to determine the nature of organic matter. Additionally, we report here on m/z 217, m/z 231, m/z 245 and m/z 259 tri-aromatic steranes found in recent sediments from each salt lake and infer their possible origin.

Key words: Biomarkers; Saltlake; Sediments.

参考文献

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[2] Fan Pu and Zhang Baisheng. Biomarker characteristics of nonmarine oils in China.Advances in organic Geochemistry, Org Geochem, 1987, 13(4/6):627-632.

[3] Fan Pu, Qian Yaorong, Zhang Baisheng. Characterisrics of biomarkers in the recent sediment from Qinghai Lake, Northwest China. Journal of Southeast Asian Sciences, Pergamon Press,1990,15(1-4).

[4] Fan Pu, R P Philp etal. Geochemical characteristics of aromatic hydrocarbons of crude oils and source rocks from different sedimentary environments. Advances in Organic Geochemistry, Org Geochem,1990,16(1-3):427-435.

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[6] Fan Pu, Li Jinggui etal. Biomarker and other hydrocarbons in Upper Sinian stromatolitic dolostones frorn Southwest China. Early Organic Evolution: Implications for Mineral and Energy Resources. Springverlag Berlin Heidelberg,1992.

[7] Fan Pu, Zhang Baisheng, WangYouxiao and Ying Guangguo. Petroleum Geochemistry of Talim Basin. Org Geochern, 1993, 20(4):499-509.

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