【作者】 秦克章；

【导师】 孙枢；

【作者基本信息】 中国科学院研究生院（地质与地球物理研究所） ， 大地构造学， 2000， 博士

【摘要】 瞄准新疆中亚型造山与大规模成矿的某些关键科学问题,立足于古生代矿床时空分布的基本地质事实的野外调查研究,从充分整理消化前人大量研究成果资料和与中亚邻国构造—成矿格局的综合对比分析入手,分析厘出主要的火山-侵入岩带和成矿带,选择那些有争议的关键区段进行重点解剖,辅以岩石学和高精度同位素年代研究。将造山作用与成矿过程的研究紧密结合起来。尝试从板块构造角度来认识北疆矿床时空分布关系及演化序列,以金属矿床时空分布样式作为大地构造环境的标志和限定,提出并论证了新疆大地构造演化——元古代古天山洋与古生代准噶尔多岛海两期大洋模式。以为寻找大型矿集区的战略靶区优选提供科学依据。 1.中亚型造山带与海西期大规模成矿 中亚地区以古生代多陆块拼合造山、中新生代陆内造山与山盆体系构成独特的地质构造格局。中亚型造山带具有多块体、多缝合带镶嵌、山盆耦合的大地构造格局,地壳经历了古生代地块拼合增生过程和中新生代陆内造山过程;陆块规模小于现代大陆板块,陆间洋盆小于现代大洋;多期蛇绿岩、高压变质岩、富碱花岗岩带的发现,指示地壳增生过程复杂多样;地壳经历了多旋回的造山和增生;中亚大型—超大型矿床总体上表现出网格状(矿结)分布特征和聚矿带的菱形镶嵌状展布规律,相比之下,环太平洋与特提斯成矿域则更具有“线性”特征;海西期的碰撞造山与成矿作用具有多岛海特征。 对新疆北部50余个已知矿床系统的同位素年代学研究,揭示出海西期(400～250Ma)是本区有色和贵金属成矿高峰期。整个北疆地区陆相环境中金、铜-镍、锡、银等矿床主要就位于晚古生代末碰撞造山挤压-伸展转变期,与大规模的块体旋转、压剪、走滑拉张以及陆内俯冲造山等独特的现象有成因联系。铜和铜镍矿,主要集中于中泥盆世、石炭纪和早二叠纪。金矿跨越时限为泥盆纪一早三叠世。其中早石炭世,主要为火山岩浅成低温型金矿床,晚石炭世一早二叠世以形成韧性剪切破碎带型金矿为特征,二者共同的特点均产出于俯冲带的边缘带近陆一侧(岛弧带-弧后盆地交接部位)。 说明晚海西期构造、岩浆、成矿作用对北疆地区具有较普遍的和重要的意义。对晚古生代花岗岩、陆相火山岩、镁铁-超镁铁杂岩的系统总结为上述认识提供了岩浆作用性质方面的证据。 2 北疆主要金属矿床划分为7大构造阶段产物 在前人基础上,按照板块构造观点并结合最新的系统同位素年代学资料将北疆古生代金属矿床(兼顾某些构造环境指向明确的非金属矿床如石棉、滑石等)划分为七大构造阶段组合: Ⅰ.稳定古陆环境中的前寒武纪矿床 Ⅱ.裂谷发育期(初始拉张期)矿床、 Ⅲ.洋壳(小洋盆)扩张阶段矿床、 Ⅳ.板块汇聚边缘早期过渡壳扩张阶段矿床、 Ⅴ.板块汇聚边缘晚期阶段挤压陆缘环境矿床、 Ⅵ.碰撞造山期矿床 Ⅶ.造山期后伸展构造阶段矿床。 3.发现新的兰闪片岩露头,矿物组合呈石榴石-白云母-绿泥石-方解石-兰闪石组合,系副变质岩。位于昭苏县南西图拉苏达坂,在已报道的阿克牙孜河上游兰闪片岩西侧约100公里。 4.依据放射虫硅质岩确定巴音沟蛇绿岩套时代上限不晚于晚泥盆世更多还原

【Abstract】 Based on field investigation of large quantity of ore deposits and multidispline comprehensive research, the paper at first analyzed some basic geological problems puzzled division and selection of copper, gold and other orebelts in Xinjiang for a long time. According to cycle processes of plate tectonics, the major Cu, Ni, Cr, Au, Pb, Zn, Fe, W, Sn and rare metal deposits of Northern Xinjiang were divided into six tectonic stages, i.e. ore deposits in primary-rift stage, spreading oceanic stage, early transitional crust stage at the convergent plate boundary, late compressional continental margin stage at the convergent plate boundary, collision orogenic stage and extensional structural stage of post-collision. And then sub-division was made according to tectonic-formation association.The ophiolites in the Northern Xinjiang are mainly distributed around Junggar and are mainly Paleozoic in age. The geochemistry of the ophiolites suggests that they can be classified into three types, MORB-like, MORB+IAB and MORB+Transitional+IAB respectively, which record the magmatism related to the formation of middle-oceanic ridge, back-arc basins, from their initial rift stage to mature spreading.Based on petrology, geochemistry and metamorphism, the back-arc basin setting of Ashele-Kelang Devonian basins in Altay was fully proved, instead of former island arc or continental marginal rift setting.The paper suggested that Huangshan-Jinerqian Cu-Ni-bearing mafic-ultramaficintrusions(single grain zircon U-Pb age 285Ma) are products of mantle diapir under continental crust tensional setting after collision orogen stage instead of ophiolite suite, analyzed the distribution features of subaerial volcanic epithermal gold deposits in Northern Xinjiang and its implications to exploration for porphyry copper deposits, and then discussed the possible inherent linkage in orogin among the paleozoic ophiolite, "Alaska-type" ultramafic-mafic complex and alkaline-rich granitoids in Northern Xinjiang.The discovery of Tuwu-Yandong Large porphyry Cu deposits is the most important breakthrough for exploration in Xinjaing even in the whole China. The single grain zircon U-Pb age of ore-bearing porphyry is 356 Ma, K-Ar age of altered sericite is 341 Ma. The evolution and metallogeny of Dananhu-Tusuquan island and Aqishan-Yamansu back-arc basin at the south were discussed. We got great prospecting success at Kalatage acid alteration-Cu-Au mineralization target in the Paleozoic uplift at the south margin of Tu-Ha basin.The geology of Xinjiang is characterized by well developments of many ophiolite belts, high-alkaline intrusive rock belts, mafic-ultramafic complexes, and ductile-shear zones. Its basins bear abundant oil and gas, its orogenic belts team with abundant Cu, Ni, Au, Cr and Fe resources. Its volcanic-intrusive formation, metal deposit types and their association show some intimate similarity with the metallogenesis of Southeast Asia Cenozoic archipelago. Taking ore deposits and volcanic-sedimentary formation as guides to development stage and evolution of regional tectonics, the evolution model of Proterozoic Prime Tianshan ocean and Paleozoic Junggar archipelago-type collisional orogen at Xinjiang was suggested.更多还原