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首页> 外文OA文献 >Formation of the world's largest molybdenum metallogenic belt: a plate-tectonic perspective on the Qinling molybdenum deposits
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Formation of the world's largest molybdenum metallogenic belt: a plate-tectonic perspective on the Qinling molybdenum deposits

机译：世界上最大的钼成矿带的形成：对秦岭钼矿床的板块构造观点

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Qinling ore belt is the largest known molybdenum belt in the world with a total reserve of >5 Mt of Mo metal. Based on the geochemical behaviour of Mo, the structural settings of the Qinling orogenic belt, and geological events in eastern China, we propose that tectonic settings are of critical importance to the formation of these ore deposits. Molybdenum is very rare in the earth with an abundance of 0.8 ppm in the continental crust. Both surface- and magmatic-hydrothermal enrichment processes are required for Mo mineralization. It can be easily oxidized to form water-soluble MoO 4- in the surface environment, especially in the Phanaerozoic, and then precipitated under anoxic conditions. Therefore, closed or semi-closed water bodies with large catchment areas and high chemical erosion rates are the most favourable locations for Mo-enriched sediments. The Qinling orogenic belt was located in the tropics during crustal collisions, such that the chemical erosion was presumably intense, whereas the Erlangping back-arc basin was probably a closed or semi-closed water body as a result of plate convergence. More than 90% of the Mo reserves so far discovered in the Qinling molybdenum belt are associated with the Palaeozoic Erlangping back-arc basin. Compiled Re-Os isotopic ages for porphyry deposits (including several carbonate vein deposits) that have been dated show peaks during 220 million years (>0.32 Mt), 145 million years (>3.5 Mt), and 115 million years (>0.84 Mt), which correlate well with the three major episodes of granitoid magmatism since the Triassic. The 220 million year episode of mineralization, represented by the Huanglongpu carbonate vein-type deposit and the Wenquan porphyry deposit, coincided with the formation of the South Qinling syn-orogenic granites as well as the Dabie ultrahigh-pressure metamorphic rocks, suggests a genetic relationship with the collision between South and North China Blocks. The 145 Ma porphyry Mo deposits, representing the main mineralization, are attributed to reactivation by ridge subduction along the lower Yangtze River belt to the east of the Qinling orogen 150-140 Ma. The 115 Ma Mo deposits likely reflect slab rollback of the northwestwards subducting Pacific plate 125-110 Ma. © 2012 Taylor and Francis Group, LLC.
机译：秦岭矿带是世界上最大的钼矿带，钼金属总储量> 5Mt。根据钼的地球化学行为，秦岭造山带的构造环境和中国东部的地质事件，我们认为构造环境对这些矿床的形成至关重要。钼在地球上非常稀有，在大陆壳中的含量为0.8 ppm。钼矿化既需要表层富集，也需要岩浆热富集。它可以很容易地在表面环境中被氧化而形成水溶性MoO 4-，特别是在生代时期，然后在缺氧条件下沉淀。因此，集水面积大，化学侵蚀率高的封闭或半封闭水体是富钼沉积物的最有利位置。秦岭造山带在地壳碰撞时位于热带，因此化学侵蚀可能是强烈的，而二郎坪后弧盆地可能是板块汇聚的封闭或半封闭水体。迄今为止，秦岭钼带中发现的钼储量中有90％以上与古生代二郎坪后弧盆地有关。已标明斑岩沉积物（包括数个碳酸盐脉沉积物）的已汇编Re-Os同位素年龄在2.2亿年（> 0.32 Mt），1.45亿年（> 3.5 Mt）和1.15亿年（> 0.84 Mt）达到峰值，这与三叠纪以来的三大类花岗岩岩浆作用有关。以黄龙铺碳酸盐岩脉型矿床和文泉斑岩矿床为代表的2.2亿年成矿期与南秦岭同造山花岗岩以及大别超高压变质岩的形成相吻合。与华南和华北街区之间的碰撞。代表主要矿化的145 Ma斑岩型钼矿床，是由于沿长江下游带至秦岭造山带150-140 Ma以东的脊俯冲作用而重新活化的。 115 Ma的钼矿床可能反映了西北俯冲125-110 Ma的西北俯冲板块。 ©2012泰勒和弗朗西斯集团有限公司。

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