青藏高原及邻区大地构造单元初步划分

Preliminary division of tectonic units of the Qinghai-Tibet Plateau and its adjacent regions

青藏高原及邻区大地构造单元的划分是当前该地区板块构造精细结构研究的关键,也是板内构造研究的基础理论问题。本文在前人工作的基础上,结合青藏高原及邻区新一轮1∶25万区域地质调查成果,基于多岛弧盆系的形成是大洋向大陆岩石圈构造体制演化转换的标志这一认识,将弧-弧、弧-陆及陆-陆碰撞结合带和夹持于其间的陆块、岩浆弧划分为一级单元,构成青藏高原及邻区构造单元的基本骨架;以南昆仑俯冲碰撞结合带和班公湖-丁青-碧土-昌宁-孟连结合带为界,划分出:泛华夏大陆早古生带秦祁昆构造区、泛华夏大陆晚古生代—三叠纪羌塘-三江构造区及冈瓦纳北缘晚古生代—中生代冈瓦纳-喜马拉雅构造区。这样的厘定不仅对青藏高原及邻区的地质科学研究具有重要的理论意义,而且对青藏高原空白区区域地质调查和成矿地质条件分析等也有重要的实际意义。

The division of tectonic units of the Qinghai-Tibet Plateau and its adjacent regions is currently not only the key to studying the minute configuration of plate tectonics but also a basic theoretical prob-lem of studying the intraplate tectonics.Based on the previous work,combined with the results of the new-round1∶250000regional geological survey,the framework of tectonic units of the Qinghai-Tibet Plateau and its adjacent regions is proposed according to the understanding that the formation of the archipelagic arc-basin system is the indication of the transformation of the oceanic lithosphere to continental lithosphere.The arc-arc,arc-continent and continent-continent collision zones and the continental blocks and magmatic arcs sandwiched in between are regarded as the first-order units,which constitute the basic framework.With the southern Kunlun subduction -collision zone and Bangong Co -Dêngqên -Bitu -Changning-Menglian suture as the boundaries the following tectonic areas may be determined from north-east to southwest:the Early Paleozoic Qinling-Qilian-Kunlun tectonic area of the pan-Cathaysian conti-nent ,the Late Paleozoic-Triassic Qiangtang-Sanjiang(Jinsha,Lanchang and Nujiang rivers)tectonic area of the pan-Cathaysian continent and the Late Paleozoic-Mesozoic Gangdise-Himalaya tectonic area on the northern margin of Gondwana.The determination of the above geological units is not only of great aca-demic significance for the geological science research on the Qinghai-Tibet Plateau and in its adjacent re-gions but also of practical significance for regional geological survey(scale1∶250000)and analysis of geo-logical conditions for mineral deposit formation in the bland areas of the Qinghai-Tibet Plateau.