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    中国西北部成矿地质特征及找矿新发现

    Metallogenic geological characteristics and newly discovered orebodies in Northwest China

    • 摘要: 提要:西北地区地处中亚构造域和特提斯构造域的交汇处,中间夹有塔里木克拉通和华北克拉通的西段。地质历史上,两个克拉通及其裂解的微陆块的形成和运动史,基本约束了中国西北部的构造发展历程。围绕克拉通及微陆块的显生宙造山带基本是其周缘增生的结果,由于大陆运移,其他大陆边缘增生的产物,在早三叠世(210 Ma)大陆汇聚中也添加了进来,这些造山带及其陆块边缘的增生是西北各种内生金属矿床的重要形成背景。同时,新元古代、晚古生代陆内与地幔柱有关的大火成岩省的发育,为铜镍等重要矿床的形成提供了条件。此外,在克拉通及其微陆块形成和后期的叠生盆地中,形成了重要的沉积和沉积变质矿床。西北地区近年来重要找矿发现,不断印证了西北克拉通边缘板块构造增生和板内幔源构造岩浆作用成矿的特点,并对传统的地质背景构造认识提出了挑战。这其中,最具经济价值和地质意义的是3个超大型金属矿床的发现:西天山早石炭世阿吾拉勒火山-次火山岩浆喷溢型磁铁矿矿床、东昆仑早泥盆世夏日哈木岩浆深部熔离-贯入型铜镍矿床和西昆仑侏罗—白垩纪火烧云构造热液型铅锌矿床。阿吾拉勒磁铁矿矿床是中国首例火山-次火山岩浆喷溢型磁铁矿矿床,可与智利的拉科超大型典型磁铁矿矿床对比,且更具有经济价值,该矿床的勘查和研究为深入理解中亚造山带天山及其邻区石炭纪裂谷型火山岩浆作用与成矿提供了研究的范例;夏日哈木铜镍矿是中国近年来最重要的铜镍矿发现,探明镍资源量已达百万吨以上,该矿床的发现为查明中国早古生代末期新的岩浆铜镍成矿事件及其找矿潜力提供了研究新区;火烧云铅锌矿床是新近发现的具有超大型资源潜力的铅锌矿床,也是喀喇昆仑—三江造山带中蕴藏的中新生代巨型铅锌成矿带上最重要的成矿发现,为深化研究青藏高原东北缘巨型铅锌成矿带的成矿物质来源和构造控矿机制提供了新的基地。

       

      Abstract: Abstract: Northwestern China lies in the intersection region between Central Asia and Tethyan tectonic domains, with Tarim craton and western North China craton in the middle. The formation and motion of the two cratons and their cracked micromassif formed during geological evolution basically constrained the process of tectonic development in Northwest China. The Phanerozoic orogenic belt surrounding cratons and micromassif resulted from peripheral accreting, with the addition of other products of continental edge accreting during continental convergence at about 210 Ma because of continental migration. All orogenic belts and continental edge accretions constituted very important formation settings of endogenic metallic ore deposits in Northwest China. In recent years, the newly discovered ore deposits in Northwest China have confirmed the idea that magmatic mineralization resulted from craton edge tectonic accreting and intraplate mantle magmatism, which challenges traditional understanding of geological tectonic settings. Among these deposits, three large or superlarge deposits, i.e., early Carboniferous Awulale volcanic-subvolcanic magmatic outpouring type magnetite deposit of Western Tianshan Mountains, early Devonian Xiarihamu magmatic Ni-Cu sulfide deposit of eastern Kunlun Mountains and Jurassic-Cretaceous Huoshaoyun tectonic hydrothermal Pb-Zn deposit in western Kunlun Mountains, have especially important economic value and geological implications. Awulale is the first volcanic-subvolcanic magma outpouring type magnetite deposit in China, which is comparable with the Laco superlarge magnetite deposit in Chile, and hence the exploration and study of Awulale are of great importance for understanding deeply rifted volcanic magmatism and mineralization of Carboniferous in Tianshan and its adjacent areas of Central Asia Orogenic Belt. The Xiarihamu magmatic Ni-Cu sulfide deposit with one million tons of Ni metal is also very important, and its discovery provides a research area for magmatism and mineralization in the early Paleozoic Ni metallogenic event and its prospecting potential. The discovery of the Huoshaoyun Pb-Zn deposit with superlarge reserves is a very important discovery in Mesozoic giant Pb-Zn metallogenic belt of the Kunlun-Sanjiang orogenic belt. These discoveries supply new basis for the understanding of ore-forming material source and structural control of ore deposits in the giant Pb-Zn metallogenic belt on the northeastern margin of the Tibetan Plateau.

       

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