湖南桃江县木瓜园钨矿床地质特征及含矿岩体成岩时代

木瓜园钨矿床是近几年在江南古陆成矿带中新发现的大型白钨矿床。该矿床产于三仙坝花岗斑岩中，白钨矿化主要类型有浸染状、细脉状和网脉状，成矿围岩蚀变类型有钾化、硅化、绢云母化、黄铁矿化和碳酸盐化等，具有斑岩型矿床的矿化和围岩蚀变特征。由于是最新发现，该矿床的矿床地质特征及成岩成矿年龄研究较少，因此笔者选取了与成矿关系密切的三仙坝花岗闪长斑岩和石英斑岩以及不同矿化类型的辉钼矿样品进行Re-Os同位素定年，获得三仙坝花岗闪长斑岩的形成时代为（222±1）Ma，石英斑岩的形成时代为（219±3）Ma，辉钼矿Re-Os模式年龄为228~223 Ma，加权平均值为226 Ma，等时线年龄为（220±21）Ma，该年龄与加权平均年龄一致，表明该矿床形成于晚三叠世。辉钼矿中w（Re）的分布范围为（70~181）×10^-6，平均为112×10^-6，反映其可能为壳幔混合来源。其形成环境为印支晚期后碰撞环境。

Geological Characteristics and Diagenetic Age of Ore-Bearing Rock of Taojiang Muguayuan Tungsten Deposit in Hunan Province

The Muguayuan W deposit in Taojiang County of Hunan Province is a newly discovered large W deposit in the west part of the Jiangnan massif, which is hosted in the Sanxianba granite porphyry. The main ore-forming types include disseminated, veinlet, and reticular types.The major alteration types of wall rocks are comprise of potassium alteration, silicification, sericitization, pyritization, and carbonation etc., typical alteration characteristics of porphyry W deposits. The different mineralizing types of molybdenum-bearing samples were selected for precise Re-Os dating, and the model ages are from 228 to 223 Ma, indicating that the deposit was formed in the Late Triassic. The Re content of molybdenite is (70-181)×10^-6, indicating that they were derived from mixed crust and mantle sources. The metallogenic environment was the post collision in the period of Late Indosinian.