华北北部中元古界下马岭组页岩有机岩石学研究  

Organic petrology of shales in the Mesoproterozoic Xiamaling Formation in the northern part of North China

作　　者：吴进 罗情勇 钟宁宁[1,2] 方子龙 段金材 张无忌 崔雅鑫 WU Jin;LUO Qingyong;ZHONG Ningning;FANG Zilong;DUAN Jincai;ZHANG Wuji;CUI Yaxin(National Key Laboratory of Petroleum Resources and Engineering,China University of Petroleum(Beijing),Beijing 102249,China;College of Geosciences,China University of Petroleum(Beijing),Beijing 102249,China)

机构地区：[1]中国石油大学(北京)油气资源与工程全国重点实验室,北京102249 [2]中国石油大学(北京)地球科学学院,北京102249

出　　处：《石油与天然气地质》2023年第5期1218-1230,共13页Oil & Gas Geology

基　　金：国家自然科学基金优秀青年基金项目(42122016);中国石油大学(北京)科学基金项目(2462020YXZZ021,2462021QNXZ001)。

摘　　要：华北北部中元古界下马岭组页岩是中国最古老的海相烃源岩之一,生源简单,有机质丰度高且成熟度低,但目前仍缺少对其显微组分面貌和成因的详细研究。通过有机岩石学方法,研究了下马岭组页岩中显微组分的组成、特征及其成因。结果表明,下马岭组页岩中显微组分组成较复杂,包括沥青质体、层状藻类体、类镜质组颗粒、矿物沥青基质和沥青铀钍矿。在显微镜下观察到类镜质组颗粒、沥青质体和层状藻类体存在光性过渡变化,它们的随机反射率呈现出逐渐减小的趋势,荧光逐渐增强。这种光性的过渡变化与它们的成因紧密相关。随着缺氧微生物降解作用的逐渐增强,层状藻类体会逐步降解形成沥青质体和类镜质组颗粒。有机质遭受放射性矿物颗粒的离子辐射聚合作用后形成沥青铀钍矿,其中放射性矿物颗粒主要为独居石和钍石。放射性矿物颗粒的热辐射对有机质成熟度有一定的影响,但是影响范围较小。The shales of the Mesoproterozoic Xiamaling Formation in the northern part of North China,which rank among China's most ancient marine source rocks,are characterized by simple biotic sources,high organic matter abundance,and low maturity.However,there is a lack of detailed study on the morphologies and origins of macerals in these shales.This study delves into the composition,characteristics,and origins of macerals in these shales using organic petrological methods.The results highlight a complex maceral composition in the Xiamaling Formation shales,encompassing bituminite,lamalginite,vitrinite-like maceral particles,mineral-bituminous groundmass,and thucholite.Notably,microscopic examinations illuminate transitional shifts in the optical properties of vitrinite-like maceral particles,bituminite,and lamalginite.These shifts—a gradually decreasing random reflectance and progressively increasing fluorescence—are intimately linked to the origins of these macerals.As lamalginite undergoes gradually enhanced anaerobic microbial degradation,it evolves into bituminite and vitrinite-like maceral particles.Additionally,the organic matter forms thucholites after experiencing ionizing radiation-induced polymerization of radioactive mineral particles,which primarily comprise monazite and thorite.The thermal radiation of these particles appears to have a certain influence on organic matter maturity only in a limited range.

关 键 词：显微组分 成因 海相烃源岩 页岩 下马岭组 中元古界 华北北部 

分 类 号：TE122.1[石油与天然气工程—油气勘探]