川西义敦地区三叠纪序地层研究新认识

详细信息

Triassic sequence stratigraphy in the Yidun region, western Sichuan

Regional Geological Surveying Party, Sichuan Bureau of Geology and Mineral Resources, Shuangliu 610213, Sichuan, China

摘要: 义敦地区处于活动岛弧带,1:5万区调将原图姆沟组自下而上分解为党恩组、列衣组、曲嘎寺组和勉戈组。以曲嘎寺组底部的I型不整合面及勉戈组底部的Ⅱ型不整合面为基准,结合内部沉积组合特征,尝试划分出3套三级层序地层,即下部层序(未见底)、中部I型碳酸盐层序和上部I I型层序(包括喇嘛垭组),在这些层序内各体系域发育齐全,特征明显。
- 活动岛弧带 /
- I型不整合 /
- II型不整合 /
- 三级层序
Abstract: The Yidun region,western Sichuan is located in an active island-arc zone where the Upper Triassic strata are well developed. According to the regional geological map on the scale of 1:50000, the formerly Tumugou Formation may be redivided, from the base upwards, into the Dang'en, Lieyi, Qugasi and Miange Formations. With the aid of the type 1 unconformity at the base of the Qugasi Formation and the type 2 unconformity at the base of the Miange Formation, three third-order sequences have been tentatively identified, including the lower sequence (not penetrated),middle type 1 sequence and upper type 2 sequence (including the Lamaya Formation). All of the depositional systems tracts are also recognized in these sequences.
- active island-arc zone /
- type 1 unconformity /
- type 2 unconformity /
- thirdo rder sequence