秦—昆三向联结构造及其构造过程的同位素年代学证据  

Qinling-Kunlun triple junction and isotope chronological evidence of its tectonic process

作　　者：孙延贵[1,2] 张国伟[1] 郭安林[1] 王瑾[3] 

机构地区：[1]西北大学地质学系 [2]青海省地质调查院,青海西宁810012 [3]青海省地质调查院

出　　处：《中国地质》2004年第4期372-378,共7页Geology in China

基　　金：国家自然科学基金重点项目(40234041)资助。

摘　　要：同属中央造山系的西秦岭和东昆仑两造山带之间的衔接转换关系,长期以来一直是有关中国中央造山系研究中的一个争论的焦点。本文在前人对发育于两造山带衔接区的布青山、阿尼玛卿以及苦海—赛什塘3条蛇绿构造混杂带大量研究的基础上,通过进一步的调查以及同位素年代学研究发现,这3条蛇绿构造混杂带并非相互独立存在,它们在物质组成、结构构造、几何形态、同位素年代学特征上构成较为典型的三向联结构造,即秦—昆三向联结构造。该构造系统基本经历了自泥盆纪的GGG型经石炭纪—二叠纪的RRA型到二叠纪晚期的SSS型三向联结构造类型的时空转化过程,最终在晚三叠世时期结束并使西秦岭与东昆仑完成了有机的衔接。The conjunctional and transitional relation between the West Qinling and East Kunlun orogenic belts, both of which belong to the Central Orogenic System, has long been a focus of dispute in the study of the Central Orogenic System of China. Based on many previous studies of the Buqin Mountain, A′nyêmaqên and Kuhai-Sêrtang ophiolitic mêlange zones in the junction between the two orogenic belts and through further survey and isotope chronological study, the authors find that the three ophiolitic mélange zones are not independent but form a typical triple junction with respect to the composition, textures and structures, geometry and isotope chronology, i.e. the Qinling-Kunlun triple junction. This tectonic system generally experienced a temporal-spatial transition process from the Devonian graben-graben-graben (GGG) type through the Carboniferous-Permian ridge-ridge-aulacogen (RRA) type to the Late Permian subduction-subduction-subduction (SSS) type of triple junction. In the Late Triassic, the process ended, and thus the junction between the West Qinling and East Kunlun was finally completed.

关 键 词：同位素年代学 西秦岭 东昆仑 造山带 泥盆纪 构造类型 二叠纪 中国 中央 联结 

分 类 号：P597.3[天文地球—地球化学]