贵州盘县新民地区关岭组中三叠世盘县动物群产出层段碳酸盐岩微相分析和古环境恢复  

The analysis of microfacies and paleaoenvironment reconstruction of Panxian Fauna from the Guanling Formation(Middle Triassic) of Xinmin,Panxian County,Guizhou

作　　者：李美铮[1] 刘楚雄[1] 江大勇[1] 郝维城[1] 孙元林[1] 孙作玉[1] 

机构地区：[1]北京大学地质学系和地质博物馆,北京100871

出　　处：《地学前缘》2011年第6期329-340,共12页Earth Science Frontiers

基　　金：国家自然科学基金面上项目(40672002);国家自然科学基金重大国际合作研究项目(40920124002)

摘　　要：通过野外观察和显微镜下碳酸盐岩薄片微相分析,以颗粒类型、颗粒基质含量对比、沉积组构、化石生物组合、化石埋藏学特征作为主要微相类型的划分依据,贵州中三叠世盘县动物群产出地层78～91层及上覆地层92层和下伏地层77层共识别出10种微相类型,在垂向上归纳为三种向上变浅的沉积相序列:开阔台地、局限台地、潮道环境。按照水深及水动力条件可以划分出深潮下带、浅潮下带沉积环境。化石层黄铁矿的存在反映了总体偏还原的沉积环境特征。颗粒含量及保存特征反映水动力条件由化石层下段较弱水动力条件到中段变强到上段再变弱的过程,这与海生爬行动物的组合特征的变化呈现出相关性。结合微相类型、岩性特征,推断盘县动物群生活在局限台地中。Through the field measurement and microscopic observation, 10 microfacies types have been recognized from the layers of 78 to 91 in the Middle Triassic Upper Member of Guanling Formation, where the Panxian Fauna occurs. The fossil-bearing beds also include their overlying layer of 92 and underlying layer of 77. The division and analysis of microfacies is based on particle types, the content contrast of particles and matrix, depositional fabric, fossil assemblages and taphonomic types. By comprehensive microfacies analyses, it is shown that the sedimentary facies of the fossikbearing beds change upward from open-carbonate platform to restricted carbonate platform and to tidal channel. The presence and abundance of pyrite indicates that the paleoenvironment was somewhat anoxic, which helped the exquisite preservation of Panxian Fauna. The grain size and content show that the hydrodynamic condition changed from weak to strong, then weak again upward to the fossil-bearing beds. It is consistent with the changes of the body size of the marine reptiles. According to the analysis of microfacies types and petrographic characteristics, the Panxian Fauna Drobablv lived in a restricted carbonate platform.

关 键 词：微相分析 古环境 盘县动物群 中三叠世 贵州 

分 类 号：P534.51[天文地球—古生物学与地层学] P588.245[天文地球—地质学]