黔北上奥陶统五峰组烃源岩有机地球化学特征及古环境意义  

Organic geochemical characteristics of hydrocarbon source rocks in Upper Ordovician Wufeng Formation of northern Guizhou and their paleo-environmental significance

作　　者：林家善[1] 谢渊[1] 刘建清[1] 赵瞻[1] 景小燕[2] 罗洋[3] 

机构地区：[1]中国地质调查局成都地质调查中心,四川成都610081 [2]中国石化西南油气分公司勘探开发研究院,四川成都610081 [3]中国石油西南油气田公司蜀南气矿,四川泸州646001

出　　处：《地质通报》2012年第11期1922-1927,共6页Geological Bulletin of China

基　　金：中国地质调查局地质调查项目<雪峰山西侧地区海相油气地质调查>(编号:1212010782003)

摘　　要：对黔北地区上奥陶统五峰组烃源岩的有机碳、类异戊间二烯烃、萜烷等有机地球化学特征进行研究,发现具有以下特征:①有机碳含量大于3%,且纵向变化小分布稳定;②有机硫碳比值倾向于高值,平均可达0.1;③Pr/Ph比值小于1,具有明显的植烷优势;④伽马蜡烷指数大于0.15;⑤δ13Corg<-30‰,普遍偏轻;⑥Ts/(Tm+Ts)值在0.361～0.518之间,平均为0.455。这些特征均指示研究区五峰期的有机物产率高,同时具有有利于有机质保存的还原环境。对比岩性及有机地球化学剖面,认为晚五峰期有机质保存条件优于早期,中五峰期上升洋流活跃。Based on a study of such organic geochemical characteristics of hydrocarbon source rocks in northern Guizhou as organic carbon, isoprenoid alkenes and terpanes, the authors have found that they have the following characteristics： （1）TOC〉3%, and its longitudinal distribution is stable; （2）the value of S/TOC is very high, with an average of 0.1; （3）the Pr/Ph ratio is lower than 1.0, which shows an obvious dominance of phytane in isoprenoids; （4）the gammacerane index is higher than 0.15; （5）the δ^13Corg- is lower than -30‰; （6）the Ts/（Tm＋Ts） ratio ranges from 0.361 to 0.518, with an average of 0.455. These characteristics indicate abundant sources of organic matter and a reduction environment. Furthermore, a comparison between lithological and organic geochemical profiles in different areas shows that the preservation condition in the late stage of Wufeng Period was better than that of the early stage, and that the upwelling was active in the middle stage of Wufeng Period.

关 键 词：五峰组 有机地球化学 上升洋流 还原环境 

分 类 号：P534.42[天文地球—古生物学与地层学] P593[天文地球—地质学]