南襄盆地泌阳凹陷湖相碳酸盐岩烃源岩沉积环境的元素地球化学标志  

Elemental Geochemical Indicators for Sedimentary Environment in Lacustrine Carbonate Source Rocks of the Biyang Depression,Nanxiang Basin

作　　者：马素萍[1] 夏燕青[1] 田春桃[1,2] 杨燕[1,2] 

机构地区：[1]中国科学院油气资源研究重点实验室,兰州730000 [2]中国科学院大学,北京100049

出　　处：《矿物岩石地球化学通报》2013年第4期456-462,共7页Bulletin of Mineralogy, Petrology and Geochemistry

基　　金：中国科学院油气资源研究重点实验室开放基金资助项目(KFJJ2010-05)

摘　　要：通过电感耦合等离子体发射光谱和等离子体质谱等测试方法,对南襄盆地泌阳凹陷古近系核桃园组湖相碳酸盐岩烃源岩进行了微量元素与稀土元素含量及指标的分析,讨论了湖相碳酸盐岩烃源岩岩石地球化学特征及其与沉积环境之间的关系。结果表明,研究区古近系核桃园组湖相碳酸盐岩烃源岩沉积期湖面升降频繁,干湿交替,但整体盐度偏高,属于厌氧的盐湖沉积环境。稀土元素存在明显分异,轻稀土富集、重稀土亏损、Eu亏损及Ce弱亏损特征,结合V/(V+Ni)比值确定其为偏还原的沉积环境。部分微量元素与稀土元素的环境参数与烃源岩有机质数量间存在密切联系,表明沉积环境对岩石有机质的富集与保存控制,水体盐度降低(整体偏高)及缺氧的还原环境为该套湖相碳酸盐岩烃源岩有机质保存提供了有利条件。We studied the characteristics of trace elements and REEs in the lacustrine carbonate source rocks of the paleogene hetaoyuan formation in the Biyang depression,Nanxiang basin by employing experimental methods of ICP-AES,ICP-MS,and Rock-evel.The geochemical characteristics of the lacustrine carbonate source rocks and their responses to the sedimentary environment were studied.The results showed that,during the depositional stage of the lacustrine carbonate source rocks in the paleogene hetaoyuan formation in this basin,the lake surface lifted frequently,and paleoclimate alternated from dry to wet back and forth.The overall salinity was relatively high,indicating an anaerobic saline sedimentary environment.The data also showed significant differentiation of REEs with enriching of LREEs and depleting of HREEs.Eu is depleted and Ce is weakly depleted.The ratio of V/（V＋Ni） and the geochemical characteristics of REEs indicated that this series of hydrocarbon source rocks were formed in partial restore depositional environment.Some environmental parameters in trace elements and REEs are closely related with the amount of the hydrocarbon source rocks,indicating that the depositional environment controls enrichment and preservation of the rock organic matter.The low salinity in salty environment and the anoxic reduction environment are favorable for preserving organic matters in the lacustrine carbonate source rocks of the paleogene hetaoyuan formation in the Biyang depression.

关 键 词：南襄盆地 泌阳凹陷 沉积环境 地球化学 微量元素 稀土元素 

分 类 号：P618.13[天文地球—矿床学]