摘要
云南永德鱼塘寨石炭－二叠界线剖面沉积连续、化石丰富，可作为滇西地区的代表性剖面，自石洞寺组至草坝山头组底部灰岩可划分出１６种主要的碳酸盐微相类型，分别形成于外陆架、中陆架和内陆架环境。
Baoshan Plate could be divided into three tectonic subunits in Late Palaeozoic.They were Baoshan-Zhenkang epicontinental sea, Kejie-Banhong platform convex and Gengma-Menglian passive continental margin. The Yutangzhai section was located in the middle part of Gengma-Menglian passive continental margin. The strata including the Pingzhang Fm. of Lower Carboniferous,Shidongsi Fm. and Yutangzhai Fm. of Upper Carboniferous and the Caobashantou Fm. and the Damingshan Fm. of Lower Permian well crop out on the Yutangzhai section. The Carboniferous system and Permian system in Yutangzhai section is continuous. It can be acted as a representative boundary section in Western Yunnan. The classification of carbonate microfacies in this paper is based on the grain types and the textures and structures of limestones. The abundance and diversity of fossils and the classification of limestones are also considered in the subdivision of carbonate microfacies. According to the above-mentioned criteria,sixteen main microfacies types can be recognized. They are: bioclastic grainstone, bioclastic packstone, bioclastic wackestone,bioclastic mudstone,echinoderm packstone,bafflestone,Ellesmerella bindstone, Anthracoperella wackestone, beresellid packstone, tubular foraminifera bindstone, oncoid grainstone, oolitic grainstone,intraclastic grainstone,laminated wackestone,echinoderm breccia and lithoclastic breccia.On the basis of micro factes analysis, a general factes model can be developed.The sedimentary environments in Yutangzhai section from the Upper Carboniferous to the Lower Permian can be divided into four parts which are attributed to inner, middle and outer shelf respectively. The lower and middle parts of Shidongsi Fm. were deposited in the middle shelf environment with moderate or good water circulation. From the lower and middle Shidongsi Fm. to the upper Shidongsi Fm. and the lower Yutangzhai Fm., the continuous transgression led to a shift of depositional environment from the middle shelf to the outer shelf which includs patch reefs, oolitic, intraclastic and bioclastic shoals and back-reef lagoons. The sedimentation processes of the middle and upper Yutangzhai Fm. briefly took place in the middle shelf environment which was. indicated by the palaeontological and petrological features. The sedimentary environment of the uppermost Yutangzhai Fm. and the lowermost Caobashantou Fm. can be assigned to the inner shelf in which the blue--green algae (Girvanella and Ellesmerella) were predominant over other fossils.
出处
《地层学杂志》
CSCD
北大核心
1995年第4期250-258,共9页
Journal of Stratigraphy
基金
国家自然科学基金
关键词
石炭纪
二叠纪
界线剖面
生物地层
沉积环境
Carboniferous-Permian boundary,carbonate microfacies,shelf,Yongde,Yunnan
