中国辽吉地区新元古代臼齿碳酸盐岩中分子化石及早期生命演化  

Molecular Fossils in Neoproterozoic Molar Tooth Carbonates from Liaoning and Jilin Provinces,China and Discussion on the Evolution of Early Life

作　　者：李艳霞[1] 旷红伟[2] 

机构地区：[1]西安石油大学油气资源学院/非常规天然气研究中心,西安710065 [2]中国地质科学院地质研究所,北京100037

出　　处：《吉林大学学报（地球科学版）》2012年第1期136-143,共8页Journal of Jilin University：Earth Science Edition

基　　金：国家科技重大专项专题项目(2011ZX05005-004-08HZ);中国石油大学(北京)油气资源与探测国家重点实验室开放课题(2009002)

摘　　要：臼齿碳酸盐岩是指具有类似大象臼齿特征并具有肠状褶皱构造的元古宙微亮晶碳酸盐岩,其成因众说纷纭。首次对分布于中国吉辽地区新元古代震旦纪(0.65～0.81Ga)的臼齿碳酸盐岩可溶有机抽提物进行了研究,从中发现了大量的分子生物化石———生物标志物,诸如正构烷烃、无环类异戊二烯烷烃、烷基环己烷、长侧链三环萜烷、藿烷、伽马蜡烷、甾烷等;同时对各类生物标志物的先体生物进行了详尽的生物门类归属,并对早期的原始生命的演化进行了深入的分析。其分子化石研究表明,MT灰岩中含有大量的原核生物细菌(蓝细菌)、古细菌(硫细菌、甲烷菌)、真核生物藻类(蓝藻、绿藻、褐藻、红藻)、真菌及原生动物。毫无疑问,臼齿构造的形成离不开生物活动的参与;同时也说明元古宙原始生物已演化到一个相当高级的程度,已蕴含埃迪卡拉纪的第一次生物大爆发。Molar-tooth carbonates（briefly called MT or microsparite carbonates） are characterized by early diagenetic sedimentary features.The term of ＇Molar-tooth＇ is named after their tapered,ptygmatically folded texture which are mainly developed in Mesoproterozoic and Neoproterozoic carbonates.The origin of these enigmatic structures have been argued.The authors investigated the MT carbonates from Simian（0.65-0.81 Ga） of Neoproterozoic Era in Liaoning and Jilin Provinces of China.A series of biomarkers found from the extracted bitumens of MT carbonates include n-alkanes,alkyl cyclohexanes,acyclic isoprenoids alkanes,extended tricyclic trepans,hopanes,gammacerane,steranes.Furthermore,their biological precursors of these hydrocarbon class are discussed particularly based on the distribution of boilipids in extant organisms.The results show that MT carbonates contain a lot of Prokaryote bacteria（oxygenic photosynthesis cyanobacteria）,Archaebacteria（sulfur bacteria,methanotroph）,Eukaryote algae（Cyanophyta,Chlorophyta,Rhodophyta,Phaeophyta）,Fungi and Protozoa.Therefore,the origin of MT carbonates should be acompanied by these early organisms.The existence of diverse biomarkers indicates that early organisms of Neoproterozoic era reached a certain extent grade in evolution and prepared ready for the great breakthrough of Edicaran life.

关 键 词：成冰纪 新元古代 臼齿构造 辽吉地区 生物标志物 生物先体 

分 类 号：Q914.63[天文地球—古生物学与地层学]