中国中央造山带内两个超高压变质带关系  

On the Relationship between the Two UHP Metamorphic Belts in the Central Orogenic Belt, China

作　　者：索书田[1] 钟增球[1] 周汉文[1] 游振东[1] 

机构地区：[1]中国地质大学地球科学学院

出　　处：《地质学报》2004年第2期156-165,共10页Acta Geologica Sinica

基　　金：国家重大基础发展项目(编号G19990755506);国家自然科学基金(编号49972067)

摘　　要：中国中央造山带内至少发育两个超高压变质带,一个是南阿尔金-柴北缘-北秦岭超高压变质带,超高压峰期变质年龄为早古生代(500～400 Ma),代表扬子与中朝克拉通间的深俯冲和碰撞带;另一个是研究程度较高的大别-苏鲁超高压和高压变质带,峰期变质年龄主体是三叠纪(250～220 Ma),代表扬子克拉通内部的陆内大陆深俯冲和碰撞带。对东秦岭看丰沟及香坊沟的变质岩片详细岩石学和构造学研究以及先期造山带尺度的构造、岩石和年代学研究资料分析证明,南阿尔金-柴北缘-北秦岭超高压变质带,向东不能与大别-苏鲁超高压和高压变质带的任一部分相连,包括南大别和西北大别超高压及高压变质岩石。相反,大别-苏鲁超高压及高压变质带,向西经桐柏山,横过南襄盆地延伸到南秦岭的西峡及商南一带。仅在东秦岭-大别山范围内,两个超高压变质带分别位于南丹断裂系南北两侧,沿造山带近平行延展,之间被一系列以断裂或剪切带为边界的岩石构造岩片相隔,不能构成横贯中国中部统一的巨型超高压变质带。任何有关中国中央造山带构造格架及构造演化模型的建立,均应考虑其内部发育两个时代和功能不同的超高压变质带。In the central erogenic belt of China, at least two UHP metamorphic belts are identified based on detailed structural analysis of the Kanfenggou and Xiangfanggou metamorphic microlithons exposed in the eastern Qinling orogen, together with previous regional structural, petrological and geochronological data at the scale of orogenic domain. The first is the South Altun—North Qaidam—North Qinling UHP metamorphic belt and the second is the Dabie—Sulu UHP and HP metamorphic belts. These two belts are separated by a series of fault-bounded tectonic slices composed of the Qinling Group, Danfeng Group and Liuling or Fuziling Group, and are different in peak age of UHP metamorphism and geodynamic implications for deep subduction and collision of the continent. Regional field and petrological relationships suggest that the Kanfenggou UHP metamorphic microlithon, which contains a large volume of coesite- and microdiamond- bearing eclogite lenses, is compatible with the rocks and structures recognized in the South Altun and North Qaidam UHP metamorphic microlithons exposed in the western part of China, and formed a large UHP metamorphic belt, up to 1000 km long along the erogenic belt. This UHP metamorphic belt represents an intercontinental deep subduction and collision belt between the Yangtze and Sino-Korean cratons, occurring during the Early Palaeozoic (500~400 Ma). On the other hand, the well-constrained Dabie—Sulu UHP and HP metamorphic belts occurred mainly during the Triassic (250~220), and were probably produced by intracontinental deep subduction and collision within the Yangtze craton. The Kanfenggou UHP metamorphic microlithon, situated in the northern Qinling erogenic belt and extending eastwards, does not appear to link with the Dabie—Sulu UHP and HP metamorphic belts, including the northwestern Dabie Mountains and the southern Dabie Mountains, along the orogen. The common occurrence of rutile and representative mineral assemblages of the Xiangfanggou microlithon exposed in the Xixia area, southern

关 键 词：中央造山带 超高压变质带 早古生代 变质年龄 

分 类 号：P588.3[天文地球—岩石学]