西藏喜马拉雅成矿带错那洞超大型铍锡钨多金属矿床的发现及意义

First discovery and implications of Cuonadong superlarge Be-W-Sn polymetallic deposit in Himalayan metallogenic belt,southern Tibet

经过地质调查工作在西藏喜马拉雅成矿带东段扎西康矿集区南部新识别出由花岗片麻岩、强变形片岩和弱变质板岩组成的错那洞大型片麻岩穹隆构造系统。穹隆核部侵入的淡色花岗岩主体为含电气石和石榴子石的二云母花岗岩,具多期侵入的特征,其中与成矿有关的中细粒电气石二云母花岗岩的锆石U-Pb年龄为(16.64±0.38)Ma。在岩体边部强变形的片岩带中新发现了环穹隆展布,层位稳定的矽卡岩带和厚大的铍多金属工业矿体。预查工作通过稀疏地表工程控制,证实铍达到超大型规模,共生的锡、钨达到大型矿床规模,揭示出西藏喜马拉雅成矿带除原有的铅锌、金锑等矿种外,铍锡钨多金属还具有巨大的找矿潜力。该首次发现和报道的超大型铍锡钨多金属矿床对再认识喜马拉雅成矿带新生代构造-岩浆演化与成矿作用,指导区域找矿具有重要的意义。

The Cuonadonggneiss dome was first identified in 2016 by field mapping and geological reconnaissance in the Zhaxikang ore concentration area in the Himalayan metallogenic belt,southern Tibet. The dome consists of a core of orthogneisses and leucogranites mantled by Paleozoic strongly deformed schists which in turn are overlain by Jurassic metasedimentary and sedimentary rocks. Leucogranite yielded a zircon U-Pb age of（16. 64 ± 0. 38） Ma,and is a Miocene tourmaline ± garnet-bearing two mica granite. A stable skarn zone and thick Be polymetallic ore bodies were newly found by the sparse exploration engineering surface in the strongly deformed schists zone around the core of the dome. Beryllium ore resources are estimated to be of up to superlarge size,and paragenetic W-Sn ore resources are of large scale. This new discovery reveals that there is a great prospecting potentiality not only for Pb-Zn and Au-Sb deposits but also for Be-W-Sn polymetallic deposits in the Himalayan metallogenic belt. Furthermore,this discovery also has a great importance for the re-understanding of the relationship between Cenozoic structural-magmatic evolution and mineralization and for regional prospecting in the Himalayan metallogenic belt.