滇东南荒田大型白钨矿床成矿作用及地质背景研究

Huang Tian tungsten, a newly discovered large fluorite-quartz vein type scheelite deposit, is located in the Laojunshan tungsten and tin polymetallic ore concentration area, southeast Yunnan province. The ore bodies are hosted in fluorite-quartz vein from the Longha Formation (Middle Cambrian; carbonate rock). The ore veins extending along a large group of NW trending fractures are several hundreds of meters long, with width of range from several centimeters to several meters. Scheelite occur as disseminated or veinlet in fluorite-quartz vein. These are not studies in genesis, geochronology and dynamics background for Huangtian tungsten deposit and granite. This application focus on metallogenesis and geological settings of Hungtian deposit. Using geochemical characteristics, zircon U–Pb geochronology and Sr-Nd-Hf-O isotopic constraints on the genesis of the Huangtian granite. Based on geological investigate,the systemic sample collection and detailed microscopic petrographic observation, using microthermomety, Raman microprobe, composition, stable isotope and Sm-Nd geochronology analysis techniques, we will explore the mechanism in metal elements migration, enrichment and disposition, refinedly reflect the ore-forming fluid evolution, exactly build the P-T-X condition for mineralization, and well reveal ore-forming chronology of Huangtian deposit. Based on the analysis of data, we will discuss the relationship between the magmatic rock, structure or metamorphism and mineralization, and accurate understanding the dynamics environment, and genesis of the deposits. As comprehensive comparison study with other typical deposits in the region could enrich and improve multi-metal metallogenic theory in the Laojunshan area. The research also provides theoretical guidance to peripheral prospecting and exploration work, and further enhance the predictive ability of new mineral deposits.

荒田萤石-石英脉型白钨矿床位于滇东南老君山钨锡多金属矿集区内，是近年来勘查发现的大型钨矿床。矿体赋存于中寒武统龙哈组(∈2l) 碳酸盐岩中，是明显受构造控制的热液脉型钨矿床，白钨矿呈浸染状、斑团状、细脉状分布于萤石-石英脉中。对矿床成因、形成时代和成矿地质背景等科学问题研究尚属空白。本申请拟对白钨矿、萤石、石英中流体包裹体进行显微测温、激光拉曼光谱、流体成分和同位素测试，开展白钨矿、萤石Sm-Nd年代学研究和矿区白垩纪三期花岗岩元素、同位素地球化学和锆石年代学测定。探索富氟流体在成矿元素迁移、富集及沉淀过程中的机制，阐明成矿流体的来源、演化过程及成矿P-T-X条件，揭示钨矿形成时代，讨论岩浆、构造或变质作用与成矿的关系，准确认识矿床形成的地球动力学环境、形成过程与矿床成因等。与研究区其他类型钨矿床进行对比研究，并总结成矿规律，为该区地质找矿工作提供科学依据。

荒田萤石-石英脉型白钨矿床位于滇东南老君山钨锡多金属矿集区内，是近年来勘查发现的大型钨矿床。矿体赋存于中寒武统龙哈组(∈2l) 碳酸盐岩中，是明显受构造控制的热液脉型钨矿床，白钨矿呈浸染状、斑团状、细脉状分布于萤石-石英脉中。本研究对白钨矿、萤石、石英中流体包裹体进行显微测温、激光拉曼光谱测试，对热液矿物/流体包裹体进行了H-O同位素测试，开展了白钨矿、萤石Sm-Nd年代学研究，同时对矿区及周缘老君山花岗岩元素、同位素地球化学和锆石年代学进行了研究。阐明了荒田矿床成矿流体的来源、性质、演化过程，分析了该矿床成因，认为荒田钨矿床与白垩纪老君山花岗岩有成因联系，是岩浆结晶晚期出溶的成矿热液沿文山-麻栗坡断裂运移，在合适物理化学条件下形成的热液脉型矿床。与其周缘南秧田超大型钨床、洒西钨矿等矿床进行对比研究后认为南秧田矽卡岩型矿床、荒田热液脉型矿床是同一个成矿系统在不同构造部位和流体演化阶段的不同表现形式。综合研究认为滇东南、桂西和越南北部地区，广泛出露高分异S型花岗岩，在其周缘形成了众多W-Sn多金属矿床，成矿时代分为三期，第一期为晚三叠世，主要形成Sn多金属矿床，与华夏板块和印支板块的碰撞有关。第二期为97~124Ma与区域钨矿床的形成有关，第三期为77~95Ma与Sn-Cu-Ag-Zn成矿有关，后两期成矿作用形成于华夏板块和印支板块碰撞后伸展阶段。