中甸地区三叠系的沉积混杂作用

THE TRIASSIC MELANGE SEDLMENTATION OF ZHONGDIAN AREA

中甸地区的三叠系沉积混杂岩十分发育 ,共有六个层位。印度早期的沉积混杂作用代表盆地早期的裂陷作用 ,形成于海岸侵蚀的崖岸垮塌 ;中三叠世的沉积混杂作用形成于台内断裂塌陷 ;卡尼早期的沉积混杂作用对应着扬子地块西缘的一次强烈的区域性伸展裂陷作用 ;哈工组 (卡尼晚期———诺利期 )中的三层沉积混杂岩是弧后裂陷作用的产物。每个沉积混杂岩层的出现 ,指示盆地可能经历了一次剧烈的裂陷作用。沉积混杂岩具有非史密斯地层学研究意义 ,它是研究隐伏的盆地基底和下伏地层的重要窗口。

The Triassic sedimentary melanges are very developed in the Zhongdian area, which consist of 6 horizons. The melange sedimentation of Early Indosinian represents the early riftogenesis of basis, formed by the cliff coast collapse because of coast erosion. The Middle Triassic melange sedimentation is formed by the fault collapse in the platform. The Early Carnian one corresponds to an intensive regional extensional riftogenesis of the west margin of Yangzi Massif. The 3 sedimentary melanges in the Hagong Formation(Late Carnian-Norian) are resulted from the back-arc riftogenesis. And the appearance of every sedimentary melange horizon indicates a possible experience of intensive riftogenesis, which is an important entrance for the study of blind basement of basin and underlying strata.