皖南埃迪卡拉系蓝田组页岩的有机质富集与孔隙发育特征  

Characteristics of organic matter enrichment and pore development of the Ediacaran Lantian Formation shales from southern Anhui Province

作　　者：曾建[1,2] 贾望鲁[1] 彭平安[1] 关成国[3] 周传明[3] 袁训来[4] 

机构地区：[1]有机地球化学国家重点实验室中国科学院广州地球化学研究所,广东广州510640 [2]中国科学院大学,北京100049 [3]资源地层学与古地理学重点实验室中国科学院南京地质古生物研究所,江苏南京210008 [4]现代古生物学和地层学国家重点实验室中国科学院南京地质古生物研究所,江苏南京210008

出　　处：《地球化学》2017年第2期158-167,共10页Geochimica

基　　金：中国科学院重点部署项目(KZZD-EW-02-3);中国科学院战略性先导专项(XDB10010204);中国科学院"一三五"规划(135TP201602)

摘　　要：中国南方广泛分布的三套海相黑色页岩中,埃迪卡拉系页岩的有机质分布与富集特征研究较为薄弱。在皖南蓝田组黑色页岩近期的研究基础上,进一步对比分析了扬子区不同沉积相页岩的有机质富集规律,通过不同显微尺度的观察技术研究了蓝田组页岩中有机质的分布特征,并根据扫描电镜观察结果采用图像分析方法评价了孔隙发育特征。结果表明:(1)埃迪卡拉系有机质富集层位主要有3套,以下扬子皖南地区沉积的蓝田组(相当于陡山沱组)Ⅱ段为最优;(2)蓝田组页岩中有机质多以不规则多边形、条带或基质分散的形式充填于矿物粒间、黄铁矿晶间以及黏土矿物集合体层间,大量的黄铁矿主要以<10μm的草莓状集合体形式出现,晶体间几乎全部被有机质充填;(3)高分辨扫描电镜图像分析表明,蓝田组页岩的孔隙以有机孔为主,孔径多小于100 nm。Among the three main sets of marine black shales widespread in South China, the Ediacaran shales have attracted little attention concerning the distribution and enrichment of organic matter （OM）. Based on recent investigations on black shales from the Lantian Formation in southern Anhui Province, the characteristics of OM enrichment for shales from various sedimentary facies of the Yangtze Block are compared and primarily summarized. The OM distribution in the Lantian Formation shales is illustrated through different scales of observation techniques, and pore characteristics are acquired through SEM image analysis. Comparison with several published results indicates that Member II of the Lantian Formation （equivalent to the Doushantuo Formation） deposited in the slope setting of southern Anhui Province is the best among three major layers with respect to OM enrichment during the Ediacaran period. OM from the Lantian Formation shales shows irregular polygon-, belt- and matrix-like shapes and largely fills among mineral particles, pyrite crystals and interlayers of clay aggregates. Pyrites exist mainly in the form of framboids smaller than 10μm, and their intercrystal voids are almost completely filled with OM. High-resolution SEM images also suggest that the pore system of the Lantian Formation shales is dominated by organic pores （pore size mostly smaller than 100 rim）.

关 键 词：埃迪卡拉系 蓝田组页岩 有机质 黄铁矿 孔隙 

分 类 号：P593[天文地球—地球化学]