摘要
[目的]埃迪卡拉纪晚期(灯影期)微生物岩是地球生命—环境协同演化的产物.[方法]在四川盆地灯影组微生物岩沉积组构划分基础上,结合不同组构的微区地球化学分析,总结微生物组构控制下的元素富集特征.[结果与结论]四川盆地灯影组微生物岩发育纹层、凝块、泡沫绵层、葡萄花边和核形石组构.纹层组构发育放线菌Actinophycus、似肾形菌Renaclis、似葛万菌Girvanellas,凝块组构发育似附枝菌Epiphiton-resembling、似肾形菌Renaclis、曲线菌Tortofimria,葡萄花边组构发育放线菌Actinophycus,泡沫绵层组构曲线菌Tortofimria,组构阴极发光呈黑色和暗红色.扫描电镜下,微生物组构发育大量诱导白云岩(呈球粒状和叠层状)、蓝细菌化石,与微生物席或EPS伴生.灯四段微生物组构Fe、S元素含量增高.灯二段葡萄花边组构富集V、Y元素,凝块组构富集V、Y、Ni元素;V、Cr、Ni、Y、LREE、HREE和ΣREE在灯四段凝块及纹层组构均有富集,Cu元素富集在凝块组构中,Zr元素富集在纹层组构中.元素富集效应显示灯影组海水以贫氧为主,灯二段海水较均一,灯四段海水分层明显,海水部分氧化.
Abstract
[Objective]Microbialites in the Late Ediacaran(Dengying)period are the product of the coordinated evolution of life and environment on earth.[Methods]Based on the sedimentary fabric division of the microbialite from the Dengying Formation in Sichuan Basin,combined with the in-situ geochemical analysis of different fabrics,this study summarizes the characteristics of element enrichment for microbial fabrics.[Results and Conclusions]The results show that the microorganisms of the Dengying Formation in Sichuan Basin are composed of stromatolite,thrombolite,foam layer,grape lace,and nucleolus.The development of Actinophycus,Renaclis,Girvanellas,and the clotting structure were similar to that of Epiphiton-resembling,Renaclis,and Tortofimria,while the grape lace,Actinophycus,foam fabric,and the cathode luminescence were black and dark red.Under the scanning electron mi-croscope(SEM),a large number of induced dolomite(spherical and laminated)and cyanobacteria fossils are ob-served in the microbial fabric,which is associated with the microbial mat(EPS),and the Fe and S elemental con-tents in the microbial fabric of the Deng4 member are increased.The lace fabric of the Deng2 member is enriched in V and Y,and the thrombolite fabric is enriched with V,Y,and Ni;Cr,Ni,Y,light(LREE),heavy(HREE)and the total rare earth elements(Σ REE)are enriched in the thrombolite and stromatolite fabric.Cu is enriched in the thrombolite fabric,and Zr is enriched in the stromatolite fabric.The element enrichment effect shows that the seawa-ter of the Dengying Formation was oxygen deficient,the seawater of Deng2 member relatively uniform,and the seawa-ter of Deng4 member stratified.The seawater was partially oxidized overall.
维普
万方数据