赣东北牛角坞钨多金属矿床地质、年代学和地球化学

牛角坞矿床位于江南造山带东段, 是近年来赣东北地区钨多金属矿产勘查取得重要进展的矿区, 钨矿体主要赋存于花岗闪长斑岩与元古界板桥组变质砂岩内外接触带, 目前探获钨资源量已达到中型规模(WO3平均品位为0.26%), 且其深部资源潜力巨大。该矿床以浅部石英脉型钨矿和深部细脉浸染型钨矿分带共生为特色, 区别于典型的石英脉型"五层楼"模式, 故对其赋矿岩体开展年代学和地球化学研究、对不同类型白钨矿进行矿物学工作和构建成矿模式具有重要意义。本文在矿床地质调查和钻孔编录的基础上, 首先厘定了牛角坞矿床矿物组合及其矿化分带特征; 获得了花岗闪长斑岩锆石U-Pb年龄为149.1±0.6Ma, 判断其为华南东部燕山期大规模岩浆热液成矿作用的产物; 赋矿花岗质岩浆岩表现为明显的过铝质钙碱性特征, 其稀土元素则为明显的右倾型配分模式, 具有弱负Eu异常, 富集Rb、Th、U等大离子亲石元素, 亏损Nb、Ti等高场强元素特征; 锆石εHf(t)集中在-15.2~-3.2, 指示其成矿岩浆来源于古元古代壳源物质重熔; 白钨矿稀土元素特征指示两类含矿热液均主体源自深部花岗质岩浆。综合年代学、矿物学和地球化学研究, 建立了牛角坞石英脉型与细脉浸染型共生钨矿床成矿模式, 为华南地区大规模钨成矿作用研究和深部勘查工作提供了新的理论依据。

Geology,chronology and geochemistry of Niujiaowu tungsten polymetallic deposit in Northeast Jiangxi Province

The Niujiaowu deposit, situated within the eastern segment of the Jiangnan orogenic belt, stands as a significant mining domain wherein the exploration of tungsten polymetallic minerals has notably advanced in the northeastern region of Jiangxi Province in recent years. Tungsten ore bodies predominantly manifest within the contact zone delineated by granodiorite-porphyry and metamorphic sandstone, specifically within the Proterozoic Banqiao Formation. Presently unearthed tungsten resources have attained a medium scale, showcasing an average WO3 grade of 0.26%. The deeper resources hold immense potential for further exploration and development. This deposit exhibits a distinct zonal symbiosis, marked by the coexistence of shallow quartz vein-type tungsten ore and deep fine vein-type tungsten ore, diverging from the conventional 'five-floor' model commonly associated with quartz vein types. Consequently, it holds significant importance to conduct geochronological and geochemical research on its ore-bearing rocks and mineralogical studies on various types of scheelite, and finally to formulate a metallogenic model. Through meticulous geological surveying and meticulous cataloging of boreholes within the deposit, the initial determination revolves around discerning the mineral association and delineating the mineralized zonation characteristics unique to the Niujiaowu deposit. The zircon U-Pb age of the granodiorite-porphyry registers at 149.1±0.6Ma, signifying its origin as a result of expansive Yanshanian magmatic hydrothermal mineralization within the eastern region of South China. The granitic magmatic rocks, blessed with ore, prominently show calc-alkaline and peraluminous traits. Simultaneously, the rare earth elements present a distinct right-skewed partitioning pattern, characterized by a subtle negative Eu anomaly, an abundance of large ion lithophile elements like Rb, Th, and U, alongside a deficiency of high field strength elements such as Nb and Ti. Notably, the zircon εHf(t) exhibits concentration within the range of -15.2~-3.2, suggesting the ore-forming magma derives from the remelting of Paleoproterozoic shell source material. The REE characteristics of scheelite indicate that the mineral-bearing hydrothermal fluids primarily stem from profound granitic magmas. Through the scrutiny of chronology, mineralogy and geochemistry, the metallogenic model delineating the Niujiaowu tungsten deposit, characterized by a combination of quartz vein-type and finely disseminated vein-type formations, was formulated. This model furnishes a novel theoretical framework for extensive tungsten mineralization investigations and profound exploration within South China.