四川义敦地区上三叠统曲嘎寺组岩相古地理研究

Sedimentary Facies and Paleogeography of the Upper Triassic Qugasi Formation in Yidun, Sichuan

对四川义敦地区上三叠统曲嘎寺组9幅1:5万区调图幅和44条剖面和沉积等厚线的综合分析研究,认为该区曲嘎寺组主体部分发育了浅海陆棚-泻湖相、开阔碳酸盐台地相、扇三角洲与碳酸盐台地交互相、浅海陆棚相、局限台地相等5种相组合,并可划分为义敦弧后前陆盆地、义敦火山弧及弧内火山洼地、沙鲁里边缘海等3个次级火山-沉积盆地,在义敦初始火山弧内发育有果德火山穹隆、根隆火山穹隆、扎翁拉火山洼地等更次一级的古地貌单元。

Study of 44 sections and sedimentary isopach in nine 1：50000 quadrangles indicates that the Upper Triassic Qugasi Formation in Yidun, Sichuan may be divided into such sedimentary facies as neritic shelf-lagoon facies, carbonate platform facies, alternating fan-shaped delta and carbonate platform facies, neritic shelf facies and restricted platform facies. Yidun back-arc foreland basin, Yidun magmatic arc and intra-arc volcanic depression and Shaluli marginal sea were developed in the Yidun region and Guode volcanic dome, Genlong volcanic dome and Zhawengla volcanic depression were developed in the Yidun initial magmatic arc.