扬子西缘鹤庆—洱源地区晚二叠世—晚三叠世盆-山演化的沉积记录

鹤庆—洱源地区位于扬子板块西缘,西邻“三江”结合带,晚二叠世—晚三叠世经历了完整的盆-山转换过程。通过分析该区地层岩性组合及沉积环境,结合构造事件,厘清了区内盆-山转换的时间格架及各阶段盆地沉积响应。研究结果表明: 区内盆地演化可分为陆内裂谷盆地、坳陷盆地和前陆盆地3个阶段; 裂谷盆地阶段沉积形成了巨厚的玄武岩沉积; 坳陷盆地阶段依次沉积了青天堡组碎屑岩、北衙组灰岩和白云岩; 前陆盆地阶段形成了中窝组和松桂组不整合界面及粗碎屑砾岩。研究成果对研究扬子西缘和“三江”特提斯构造带盆-山演化具有重要的科学意义。

Sedimentary records of basin-mountain evolution during Late Permian to Late Triassic in Heqing-Eryuan area in western Yangtze Block

Heqing-Eryuan area is located in the western Yangtze Block,and adjacent to Sanjiang juncture zone in the west,which has been undergoing a complete basin-mountain conversion from Late Permian to Late Triassic.Combining with the tectonic events,the researchers in this paper analyzed the stratigraphic lithology and sedimentary environment,and revealed the temporal pattern of basin-mountain conversion and basin sedimentary responses of each stage.The results show the basin evolution of this area can be divided into 3 stages:The intraplate rifting basin stage,the depression basin stage and the foreland basin stage.The huge thick basalt deposition was formed during depression basin stage,and Qingtianbao Formation clastic rocks and Beiya Formation dolomite and limestone was successively formed during rifting basin stage.Besides,the unconformities and hybrid conglomerates were formed in Zhongwo Formation and Songgui Formation during foreland basin stage.This work has scientific significance for the research of basin-mountain conversion in the western Yangtze Block and Sanjiang juncture zone.