摘要
分布在青藏高原北缘的阿尔金-祁连-柴北缘早古生代造山系被认为是原特提斯构造域最北部的构造拼合体。与其北侧具有长期增生历史的中亚造山系相比,特提斯造山拼合体被认为是各种来自冈瓦纳大陆北部大陆块体相互碰撞的产物。然而,与典型的阿尔卑斯和喜马拉雅碰撞造山带相比,阿尔金-祁连-柴北缘早古生代造山系包括有大量蛇绿岩、弧岩浆杂岩、俯冲-增生杂岩等,因此一些学者认为青藏高原北部的早古生代造山系为沿塔里木和华北克拉通边界向南逐渐增生的增生型造山带。但是,增生造山模式又很难解释南阿尔金-柴北缘地区普遍存在的与大陆俯冲有关的UHP变质岩、广泛分布的巴罗式变质作用和相关的岩浆作用,以及与碰撞造山有关的变形构造等。在本文中,通过对已有研究资料的综合总结,结合一些新的研究资料,我们提出在青藏高原东北缘的阿尔金-祁连-柴北缘造山系中,早古生代时期存在两种不同类型的造山作用,即增生和碰撞造山作用,其主要标志是北祁连-北阿尔金的HP/LT变质带、蛇绿混杂岩及与洋壳俯冲有关的构造岩浆作用,以及分布在柴北缘-南阿尔金与大陆俯冲和陆陆碰撞有关的UHP变质带、区域巴罗式变质作用、深熔作用、相关的岩浆活动及伸展垮塌作用等,并建立了一个反映原特提斯洋俯冲、增生、闭合及碰撞造山作用的构造模式。
The Ahun-Qilian-North Qaidam orogenic system, which is located in northern Tibet, was considered as the northernmost orogenic collage of the Proto-Tethyan domain. In contrast to the central Asia Orogen to the north characterized by long-lived accretionary processes, the architecture of the Tethyan orogenic collage was regarded as resulting from collisions between various continental terranes derived from the northern margin of Gondwana. However, in contrast to typical collisonal orogens (e. g. Alps and Himalaya orogens), the Ahun-Qilian-North Qaidam orogenic system includes abundant ophiolites, arc magmatic rocks and subduction- accretion complex, and thus some authors had regarded the orogenic system of the North Tibet as a typical accretionary orogen built by the development of an evolving arc-accretion complex growing southward along the margin of the Tarim and North China Craton during Paleozoic. However, this view is difficult to explain the common occurrence of continent-type UHP metamorphic rocks, broadly distributed Barrovian type metamorphism and associated granitic magmatism as well as deformation structure related to collisional orogenesis in the South Ahun and North Qaidam Mountains. In this contribution, based on published data and our new data, we propose that two distinct orogenesises, i.e. accretion/collision orogenesises, developed in the Altun-Qilian-Qaidam during Early Palaeozoic time. The diagnostic marks include I-IP/LT metamorphic belts, ophiolitic m6|ange and arc magmatic rocks related to subduction-accretion, which mainly occur in the North Qilian Mountains and North Ahun, and UHP metamorphism, Barrovian type metamorphism, associated grantic magmatism, extension collapse resulted from continental subduction and continent-continent collision along the South Ahun-North Qaidam. We also build a tectonic model showing the tectonic evolution related to the subduction, accretion and closure of Proto-Tethyan Ocean.
出处
《岩石学报》
SCIE
EI
CAS
CSCD
北大核心
2015年第12期3531-3554,共24页
Acta Petrologica Sinica
基金
公益性行业基金(201011034)
中国地质调查局地质调查项目(12120114078301
12120115027001)
国家自然科学基金项目(41272210
41572180)联合资助
关键词
增生造山
碰撞造山
原特提斯洋
早古生代
阿尔金-祁连-柴北缘
Accretionary orogeny
Collisional orogeny
Proto-Tethyan Ocean
Early Paleozoic
Altun-Qilian-North Qaidam