Macro-and microfeatures of Early Cambrian dolomitic microbialites from Tarim Basin, China  

作　　者：Ying Li Hong-Xia Jiang Ya-Sheng Wu Wen-Qing Pan Bao-Shou Zhang Chong-Hao Sun Guo Yang 

机构地区：[1]Key Laboratory of Cenozoic Geology and Environment,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China [2]Innovation Academy for Earth Science,Chinese Academy of Sciences,Beijing 100029,China [3]University of Chinese Academy of Sciences,Beijing 100049,China [4]Hebei GEO University,Shijiazhuang 050031,Hebei Province,China [5]Research Institute of Petroleum Exploration and Development,Tarim Oilfield Company,PetroChina,Korla 841000,Xinjiang Uygur Autonomous Region,China

出　　处：《Journal of Palaeogeography》2021年第1期19-38,共20页古地理学报（英文版）

基　　金：This study was supported by the National Natural Science Foundation of China(Grant No.41972320);National Major Science and Technology Projects of China(Grant No.2016ZX05004004-005);the Strategic Priority Research Program(B)of Chinese Academy of Sciences(Grant No.XDB26000000)。

摘　　要：The fabrics of microbialites preserved in limestones are generally better than in dolostones. What are the fabrics of the microbialites preserved in heavily dolomitized dolostones? This paper presents an example of a strongly dolomitized Cambrian microbialite profile. The Xiaoerblak Formation(Cambrian Series 2 Stage 3 and lower Stage 4)of the Sugaitblak section in Aksu, Xinjiang Uygur Autonomous Region, China is mainly composed of microbial dolostones. Due to strong alteration by diagenesis, their features, formation and environments have not been fully understood. Here, based on detailed observation on outcrops and thin sections, we show that this formation comprises four kinds of microbialites: laminite, thrombolite, thrombolitic laminite, and Renalcis framestone, in five intervals(Interval I to Interval V). We identified three main types of microbialite fabrics, i.e., clotted fabric, laminated fabric and skeletal fabric, and established a high-resolution vertical evolution sequence of the microbialites. The clotted fabric and the laminated fabric were further divided into subtypes. We found that the original fabrics were mainly affected by dolomitization, recrystallization and dissolution, and the alteration degree of the microbialite fabric is stronger in the lower part of this formation. The laminated fabric has the strongest resistance to diagenesis,followed by the clotted fabric. Based on studies of different rock types and sedimentary structures, we concluded that the sedimentary environment of Xiaoerblak Formation consists of three settings: a) Intervals I to III formed in restricted tidal flat environments, b) Interval IV and the lower part of Interval V in restricted deep subtidal environments, and c) upper part of Interval V in shallowing-up open subtidal environments.

关 键 词：CAMBRIAN MICROBIALITE Thrombolite FABRICS Laminite 

分 类 号：P534.41[天文地球—古生物学与地层学] P588.245[天文地球—地质学]