内蒙古扎赉特旗中二叠统岩石地层、生物地层特征及沉积环境分析

THE MIDDLE PERMIAN LITHOSTRATIGRAPHY,BIOSTRATIGRAPHY AND SEDIMENTARY ENVIRONMENTS OF THE JLAID QI,INNER MONGOLIA

对扎赉特旗地区塔本毛都和查干楚鲁一带出露的四甲山组、柳条沟组进行了实测和系统采样。根据生物化石组合的特征将其划分为3个生物组合带,即Monodiexodina-Parafusulina,Codonofusiella-Pseudodoliolina组合带,Waagenophyllum-Wentzelella珊瑚组合带。它们产于中二叠统祥播阶至冷坞阶的地层。结合岩性特征及层位对比,塔本毛都剖面的1~6层、7~15层与查干楚鲁剖面1~11层及12~20层分别划归为四甲山组与柳条沟组。沉积相分析表明,剖面可识别出4种沉积相和5种沉积微相。沉积环境为稳定的碳酸盐台地环境,不同沉积相组成一个完整的碳酸盐台地的发育旋回。

Survey and systematic sampling were conducted for the Sijiashan and Liutiaogou formations at the Tabenmaodu and Chaganculu section in Jlaid Qi,Inner Mongolia.On the basis of paleontological data,three biostratigraphic zones can be recognized： namely the Monodiexodina-Parafusulina and Codonofusiella-Pseudodoliolina fusulinid assemblages and Waagenophyllum-Wentzelella coral assemblage.The age of the Sijiashan and Liutiaogou formations is is considered to be the Xiangboan Stage to the Lengwuan Stage of the Middle Permian.On the basis of lithostratigraphic features,beds 1~6 at the Tabenmaodu section and beds 1~11 at the Chaganculu section are considered to be the Sijiashan Formation,whereas beds 7~15 at the Tabenmaodu section and beds 12~20 at the Chaganculu section represent the Liutiaogou Formation.According to the analysis of the sedimentary facies in this area,four sedimentary facies and five microfacies are recognized.The middle Permain in this area is dominated by carbonate platformfacies,and a complete carbonate platform depositional cycle consisting of different facies can be recognized.