Tungsten mineralization during slab subduction: A case study from the Huxingshan deposit in northeastern Hunan Province, South China
Tungsten mineralization during slab subduction: A case study from the Huxingshan deposit in northeastern Hunan Province, South China
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板片俯冲过程中的钨成矿作用：以湖南省东北部虎行山矿床为例
DOI：
10.1016/j.oregeorev.2020.103657
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发表时间：
2020
影响因子：
3.3
通讯作者：
Wang Kai Lang
中科院分区：
文献类型：
--
作者：
Xu Jun-Wei;Lai Jian-Qing;Li Bin;Lu An-Huai;Rocholl Alex;er;Dick Jeffry M.;Peng Jian-Tang;Wang Kai Lang
虎形山钨存款（~0.21 Mt，0.3 wt%WO 3）位于中国南方江南地块钨矿带。在这里，W矿化仅限于侵入下寒武统地层中各种围岩的石英和白云母-石英脉。白云母-石英脉中流体包裹体的Rb-Sr等时线年龄134 ± 2 Ma）与虎形山花岗岩的锆石U-Pb结晶年龄（137.8 ± 0.5 Ma）一致，表明两类岩石有密切的成因联系。虎形山花岗岩的锆石εHf（t）值（−16.2 ~+6.6）与特别相关的变质沉积岩板溪群和冷家溪群的锆石εHf（t）值重叠，与新元古代扬子下地壳物质熔融并有地幔熔体输入源区的结果一致。我们认为，钨和铍花岗岩的高度分化的签名可能继承了源岩的起源化学和进一步修改高度分离结晶，而不是流体-岩石相互作用过程。在这一过程中，钨和铍在残余熔体/流体中富集，最终从凝固熔体中分离出来，并通过大规模的流体运动进入围岩，沿沿着矽卡岩和云英岩层位沉淀出白钨矿和绿柱石。概述的过程很可能是耦合到大规模的大陆地壳熔融和相关的花岗质岩浆活动的制度下，俯冲的古太平洋板块下中国南方和随后的撕裂板。新发现的虎形山存款矿床显示了江南地块西北部巨大的找矿潜力。
The Huxingshan tungsten deposit (~0.21 Mt at 0.3 wt% WO3) is located in the Jiangnan Massif tungsten ore belt, South China. Here, the W mineralization is restricted to quartz and muscovite-quartz veins intruding variable country rocks of the Lower Cambrian strata. Rb-Sr isochron ages derived from fluid inclusions trapped in muscovite-quartz veins (ca. 134 ± 2 Ma) agree with the zircon U–Pb crystallization age of the associated Huxingshan granite (137.8 ± 0.5 Ma) and may thus suggest a close petrogenetic relationship between both rock types. ZirconεHf(t) values of the Huxingshan granite (−16.2 to +6.6) overlap with those of the specially related metasedimentary Banxi and Lengjiaxi Groups, consistent with melting of Neoproterozoic Yangtze lower crustal materials with mantle melts input to the source. We suggest that the highly differentiated signatures of tungsten and beryllium granite might be inherited from the origin chemistry of source rocks and further modified by highly fractional crystallization rather than by fluid-rock interaction processes. During this process, tungsten and beryllium was enriched in the residual melts/fluids, which finally separated from the solidifying melt body and were introduced into the county rock to precipitate scheelite and beryl along skarn and greisen horizons by large-scale fluid movements. The outlined processes are likely to be coupled to large-scale melting of continental crust and associated granitic magmatism under a regime of subduction of the paleo-Pacific Plate beneath South China and subsequent tearing of the slab. The newly discovered Huxingshan deposit underlines the huge prospecting potential for the northwestern Jiangnan Massif.