西藏查当地区中侏罗统雀莫错组地层沉积环境分析

Analysis on the Sedimentary Environment of the Middle Jurassic Quemocuo Formation of Chadang Area in Tibet

通过对查当地区的雀莫错组地层进行剖面测制,研究了其岩石组合特征,并将其划分为三个段级岩石地层单位。其中,一段以灰白色、粉灰色、紫红色粗-中粒岩屑石英砂岩、中细粒岩屑石英砂岩为主;二段以绿灰色、紫红色、黄绿色中-细粒岩屑石英砂岩、绿灰色(白云质或含铁质)粉砂岩为主;三段以紫红色、暗紫色、灰紫色粉砂岩、中-细粒岩屑石英砂岩、中-细粒(长石)岩屑砂岩为主。基于岩石组特征推测其沉积环境为障壁性的潮坪环境和泻潮环境。

Through the profile measuring of the quemocuo formation in Chadang area,the characteristics of its rock association were studied in detail,and it is divided into three sections.The first section was dominated by grayish-white,pinkish-gray,purple-red coarse-medium lithic quartz sandstone and medium-fine lithic quartz sandstone.The second section was dominated by green-gray,purple-red,yellow-green medium-fine lithic quartz sandstone,green-gray(dolomitic or iron-bearing)siltstone.The third section was dominated by purple,dark-purple,gray-purple siltstone,medium-fine grained lithic quartz sandstone and medium-fine grained(feld⁃spar)lithic sandstone.It is inferred that the sedimentary environment can be classified as barrier tidal flat envi⁃ronment and tidal discharged environment in the study area.