地质论评2016，Vol.62Issue(5)：1134-1148,15.DOI:10.16509/j.georeview.2016.05.004
广西隆安下石炭统都结微生物岩微相特征与沉积环境研究
Sedimentary Environment and Microfacies Analysis of the Lower Carboniferous Microbial Carbonates in the Dujie Village, Long’an County,Guangxi
摘要
Abstract
Objectives:The thick-bedded Dujie microbial carbonates are widespread and well exposed in Long ’an county,Guangxi.The microbial carbonates occur in the middle—upper part of Du’an Formation.Until recently, Early Carboniferous carbonate buildups were reported as relatively rare in south China,and very few work on Dujie microbial carbonates has been done.In this study,we focus on the microfacies analysis to establish depositional facies models and identify sedimentary environment. <br> Methods:Microfacies is considered as the total of all sedimentological and paleontological data which can be described and classified from thin sections,polished slabs,rock samples and so on.Microfacies analysis consists of two parts of work:① Field geology,including mapping and profiling,is a prerequisite for successful microfacies analysis;② Thin-section studies,observing microscopic features of limestones by polarizing microscope and using microfacies criteria in describing and classifying limestones. <br> Results:Dujie microbial carbonates contain various organisms including microbe,foraminifera,echinoderm, calcisphere,brachiopod etc..Fossiliferous grainstones and boundstones are two common lithofacies in the microbial carbonates.Eight microfacies types grouped into three facies zones are recognized by petrographic analysis.They are (MF1)Coated bioclastic grainstone;(MF2)Peloidal grainstone with shell;(MF3)Non-laminated peloidal grainstone;(MF4)Aggregate-grain grainstone;(MF5)Densely laminated bindstone;(MF6)Ooid grainstone with intraclast;(MF7 ) Ooid grainstone;(MF8 ) Dolomitic ooid grainstone.The sedimentary processes of Dujie microbial carbonates include (FZ1 )the shoal of platform margin facies,(FZ2 )the open platform facies and (FZ3 )the restricted platform facies. <br> Conclusions:Thus,the established depositional facies models and geologic foundation data indicate that:①Dujie microbial carbonates are distributed in shallow water carbonate platform within low latitudes;② Dujie microbial carbonates have 3 developmental stages;③ the sea level shows a falling trend roughly,although it changes within a narrow range.Dujie microbial carbonates develop on the eve of the Late Paleozoic ice age and the Serpukhovian (Carboniferous ) mass extinction.With the enrichment of microbial carbonates and the lack of metazoan reefs,the biological composition in marine ecosystems has changed significantly during the period from late Visean to Serpukhovian.Based on the above,the effects of the glaciation in Gondwanal and on the low latitudes of the Northern Hemisphere from the perspective of microbial carbonates is analysised preliminary in the present study.关键词
广西/都结微生物岩/下石炭统/微相/沉积环境Key words
Guangxi/Dujie microbial carbonates/Lower Carboniferous/microfacies/sedimentary environment引用本文复制引用
苗卓伟,张永利,巩恩普,关长庆,阮氏梅香,黄文韬,王邓..广西隆安下石炭统都结微生物岩微相特征与沉积环境研究[J].地质论评,2016,62(5):1134-1148,15.基金项目
本文为国家自然基金资助项目（编号41202018、41572004）、教育部高等学校博士学科点专项科研基金资助项目（编号20120042110027、20110042120043）、中央高校基本科研业务专项资金资助项目（编号N120401001）的成果。 （）
