南秦岭勉略构造混杂岩带非史密斯地层系统和地层格架

Stratigraphic System and Framework of Non-Smith Strata in Mianxian-Lueyang Tectonic Melange Belt, South Qinling Mountains

南秦岭西段勉略构造混杂岩带是由不同的构造岩片组成的非史密斯地层区。本文建立了勉略构造带太古宙—石炭纪的地层系统。勉略构造带及其邻区地层格架分析表明晚震旦世—寒武纪勉略构造带及中秦岭为扬子板块北缘的一部分。奥陶纪—志留纪大致沿勉略构造带形成南秦岭裂陷槽。泥盆纪—石炭纪该裂陷槽进一步开裂形成勉略洋。该洋盆从石炭纪开始俯冲萎缩并最终于三叠纪后期碰撞、闭合并造山。

Mianxian - Lueyang ophiolitic melange belt of South Qinling is a non-smith stratigraphic region , which consists of many structural slices of different ages. In this paper, a new stratigraphi-cal system of Mianxian - Lueyang ophiolitic melange belt is built, which is made up of strata from Archeozoic to Carboniferous. The stratigraphical framework of Mianxian - Lueyang ophiolitic melange belt and its adjacent regions provides information of palaeoceanographic evolution. Mianxian - Lueyang ophiolitic melange belt and its adjacent regions are located on the northern edge of Yangtze plate from the Late Sinian to Cambrian. A rift trough along Mianxian -Lueyang ophiolitic melange belt was formed from Ordovician to Silurian. Further rifting of this rift trough formed an open ocean from Devonian to Carboniferous, which was gradually closed by subduction and collision among Yangtze plate, Qinling microplate and north China plate, and formed an erogenic belt from Carboniferous to Triassic.