摘要
著名的盘古山大型钨矿与深部隐伏花岗岩体具有密切成因关系,但因该岩体隐伏深,相关研究资料较为欠缺,很大程度上影响了对矿床岩浆-热液-成矿作用的深入认识。南岭科学钻探(SP-NLSD-2)揭露该岩体后,本文对其开展了岩石学和元素地球化学研究。结果表明,该岩体具有超酸性、富碱、贫钠富钾等特征,属于准铝-过铝质高钾钙碱性花岗岩。形成该岩体的花岗岩浆为高度分异演化的残浆,W、Bi等元素含量明显高于南岭燕山期花岗岩,为盘古山钨铋矿床的形成提供了丰富的矿质。岩浆演化至云英岩化阶段时,岩浆中的Mo、Bi、Cu、Pb及REE含量增加,而W、Sn含量则因已转移到岩浆期后热液而降低。岩体形成于板内伸展环境。
Pangushan granite is genetically related to the well-known Pangushan large-sized tungsten deposit. However, due to great depth, its petrologic and geochemical data had been lacking until it was discovered by the Nanling Scientific Drilling Project(SP-NLSD-2) recently. In this paper, the petrologic and geochemical study conducted by the authors is reported. The granite is found to be ultra-acidic, alkali-rich, Na-poor, K-rich, meta-to weak-peraluminous and K-high calc-alkaline. Its corresponding granitic magma is highly evolved and W and Bi values are significantly higher than their average values in Yanshanian granite in Nanling region, indicating that they were the major ore-forming material source. When the granitic magma was evolved to the greisenization stage, Mo, Bi, Cu, Pb and REE were enriched, while W and Sn were depleted because of their migration into the hydrothermal solution. The intrusion of the Pangushan granite happened during intraplate extension.