【作者】 韩芳林；

【导师】 张洪涛； 陈仁义；

【作者基本信息】 中国地质大学（北京） ， 矿物、岩石、矿床， 2006， 博士

【摘要】 西昆仑造山带是一个长期演化的复杂增生造山带。该造山带的造山过程即震旦纪-寒武纪扩张形成的秦祁昆洋(原特提斯洋)大洋板块从奥陶纪至三叠纪连续向北侧塔里木板块之下的俯冲,塔里木板块向南增生过程,地史跨度达500多Ma。 震旦纪-寒武纪RODINIA超大陆裂解,形成原特提斯洋。在塔里木大陆板块大洋板块之间存在一个多岛洋盆过度区,过度区由亲塔里木板块的三个微陆块分布其间的小洋盆、裂谷盆地或裂陷海槽构成。奥陶纪开始原特提斯大洋板块沿多岛洋过渡区南缘康西瓦-苏巴什一线开始向北俯冲,使上盘多岛洋区变成岛弧。之后,大洋板块向南退缩,沿俯冲带形成的增生楔向南推进,位于增生楔北侧的岛弧也随之向南跟进。其间经历了晚奥陶世和中二叠世末两次弧/陆碰撞和随之发生的俯冲方式的转化调整,出现统一过程的阶段性构造体制变化。晚二叠世-三叠纪,特提斯洋不再发生洋底扩张,残留盆地被大量陆源碎屑充填的同时,受南侧发生裂离的冈瓦纳大陆块体向北的挤压,残余洋壳继续向北被动俯冲,盆地沉积物发生褶冲变形,于侏罗纪隆起成山,也最终完成了洋陆转化。 受地质背景控制,西昆仑造山带增生演化过程的成矿作用也很有规律,总体是矿种和类型由简单向多样转变,成矿潜力从弱到强转变。主要成矿作用发生在三个演化阶段。最早在震旦纪-寒武纪RODINIA超大陆裂解形成的小洋盆等裂陷盆地中产生了从基性侵入-火山和火山喷气—沉积作用有关的磁铁矿—赤铁矿。晚古生代为典型的沟—弧—(多)盆构造体制,沿早古生代弧陆碰撞带再次伸展形成的断续相连的三个裂谷盆地构成西昆仑一个重要的铜铅锌成矿带,有6种成矿类型。三叠纪—侏罗纪残余洋壳的向北俯冲,形成了西昆仑造山带规模最大的花岗岩带,同时在也发生了极不均匀的变质作用,形成三个规模不等的热变质穹隆构造。与岩浆侵入和热变质穹隆有关的成矿作用是西昆仑造山带成矿的最高潮,构成西昆仑最具找矿潜力的成矿带。洋壳熔部分融形成的“I”型花岗岩类形成斑岩型铜(银)矿,被洋壳携带的深海沉积岩部分熔融形成的“S”型花形成稀土和稀有金属矿产。热变质穹隆形成变质改造—热液脉型与变质级别相吻合的铁、铜、铅、锌、金、锑、汞矿。早古生代增生楔中的远洋沉积岩为热隆成矿的矿源层,一种是冷水沉积的富铁泥岩,另一种是洋底热水成因的铁铜铅锌矿(富金锰镍钴)。更多还原

【Abstract】 Based on the recent data of the regional geological surveying (1:250000) and previous studies in the western Kunlun orogen, the basic and economic geology were studied elaborately from field and geochemical studies. Magmatic arc is the key to study tectonic evolution of the western Kun orogen in this paper, and some tectonic units, such as Sinian-Cambrian rock assemblages of continental breakup, Ordovician-Silurian and late-Paleozoic accretionary wedges, and Mesozoic domes were defined. Geology, tectonic units, tectonic evolution and dynamical processes, and mineralization of the western Kunlun orogen were studied systematically, and the geological and resource map with a scale of 1:1000000 of this belt was compiled and modified, which can reflect the tectonic evolution and mineralization of the western Kunlun orogen objectively.The western Kunlun orogen is a complicated accretionary orogen, which was formed by continuous subduction of the Sinian to Cambrian Qin-Qi-Kun Ocean (proto-Tethys) to the Tarim plate in the Ordovician-Silurian, Devonian-middle Permian, late Permian-Triassic, and Jurassic in different mechanisms. Accretion southward along the southern margin of the Tarim plate took place and lasted more 500 Ma periods. This orogeny took place initially along the Kangxiwa-Subashi areas, paleo-ocean subducted northward and the trench retreated southward in these areas.The mineralization as an essential part of the orogen was controlled by the geological setting fully in the western Kunlun Orogen, and the special ore deposits were developed in different tectonic history. Mineral assemblage and ore deposit types also changed regularly during the orogen.The Rodinia Supper-continent broke-up in the Sinian-Cambrian and began spreading in the late-Sunian to form the proto-Tethys ocean. An archipelago between the Tarim plate and the oceanic plate in the south margin of the Kanxiwa-Subashi areas was developed, which consisted of Kulangnagu, Sangzhutage and Saitula micro-continental blocks, and Kegang, Kudi and Qimanyute small ocean basins and rifted basins or fractured ocean trough. Ore-forming system of the magnetite-hematite was produced, which was related to basic intrusion-volcano and volcano exhalative sedimentation.Ordovician-Silurian, proto-Tethys subducted northward along the southern margin (Kangxiwa-Subashi area) of the transitional type of blocks of the archipelago at a low dip of subduction zone, and the island-arc formed in front of the overriding plate. These island arcs became into island-arc chain slowly and collided with Tarim plate in the Late Ordovician along the Kegang-Kudi-QImanyute areas. Additionally, early Ordovician-early Silurian subduction-related granite belt and late Ordovician collision-related granites with hydrothermal vein- and skam-type Fe-Co deposits and ’Hetian’ jade deposits respectively were formed during this subduction-accretion. The granite belt related to subduction became younger southward. Accretionary prism was formed and progressively widened along the trench in the forearc area;mineralization was related to the pelagic sediments of this prism, which consists of Fe- riched mudstone and Fe-Cu-Pb-Zn deposits bearing Mn-Ni-Co. This prism is the source bed of Mesozoic mineralization.In the Devonian-Permian, paleo-Tethys subducted northward continuously, but the dipping angle of downgoing plate became steep and the trench-arc system was formed. Arc-continent collision took place in the mid-Permian, which is the second accretion orogen in the western Kunlun. Late Paleozoic island arc has the characters of continental margin arc but different from the early continental arc. Early Paleozoic accretionary wedge became into the basement of the late Paleozoic island arc. The accretionary prism consists of Flysh and seamount (basalt and limestone) respectively, were formed in the forearc area;back spreading took place between the early-Paleozoic accretionary wedge and island arc to form the Subashi small ocean basin within the Kangxiwa-Subashi tectonic belt. The Kungaishan, KUerliang and Aqiang rifted basins were formed along the suture between early-Paleozoic island arc and Tarim plate. These basins are equal to the three proto-microblocks, and are important Cu and Pb-Zn mineralized belt. Five types of mineralization were formed within them.In the late Permian-Triassic, the extension of the Tethys ended but became into a remnant ocean basin, and the Gondwana continent moved northward. Then, Trissic remnant basin was filled by clastic rocks and folded, and the ocean became into continent. Accretionary orogen ended in the western Kun orogen.In the Jurassic, early to late Paleozoic accretionary wedge and the Bayankalashan Group in the south of the Kangxiwa fault uplifted and were lack of deposits. However, deep tectonic activities were continuous. The downgoing oceanic crust and sediments were melted in the deep and plutoned into the Paleozoic accretionary wedge to form Triassic-Jurassic granitoid belt with huge scale in the western Kunlun orogen. Oceanic crust partly melted to form I-type granitoid, which associated with S-type granitoid formed by deep-water sediments. Porphyry Cu(-Mo)deposits, and rare-earth and related rare metal resources were formed by I- and S-type granitoid respectively. Synchronically, Muji-Tashikuergan, Kangxiwa, and Huangyangling domains and abundant Fe-Cu-Pb-Zn-Au-Ag-Sb mineral resources were formed by regional metamorphism of the early Paleozoic accretionary prism. The mineral deposits show distinctive metallogenic zoning and different metamorphic grade formed its relatively mineral deposit. Mineralization controlled by plutons and domes is the peak metallogenic epoch in the western Kunlun orogen.更多还原