赣北香炉山白钨矿床的同位素年代学研究及其地质意义

Isochronology Study on the Xianglushan Scheelite Deposit in North Jiangxi Province and Its Geological Significance

赣南钨矿闻名世界,但赣北—皖南也存在钨的矿集区,香炉山就是其中之一。该矿床属矽卡岩型层状白钨矿床,与赣南钨矿明显不同。本文通过对矿区内与成矿作用关系密切的花岗岩、白钨矿及其共生的石英矿物的年代学研究,分别获得黑云母花岗岩全岩Rb-Sr等时线年龄为126.2±2.6Ma(95%可信度)、白钨矿Sm-Nd等时线年龄和石英矿物Rb-Sr等时线年龄为121±11Ma(95%可信度)和128±3Ma(95%可信度)。上述测定结果表明,其成矿时代与区内花岗岩岩浆侵位所发生的时间有明显的耦合关系,与区域上同时代形成的斑岩型锡矿(如岩背)及铌钽矿相似,均属燕山晚期岩浆活动的产物。

Ganbei-Wannan area （north Jiangxi province and south Anhui province） is another important tungsten deposit -intensive areas besides the Gannan area （south Jiangxi province）. The Xianglushan scheelite deposit is one of the deposits in the Ganbei area. This deposit belongs to bedded skarn-related scheelite deposit, which distinguishes from the tungsten deposits in Gannan. This article presents the isochronology study on the mineralization-related granite, scheelite and quartz. The dating results show that the Rb-Sr whole-rock isochron age of the biotite granite is 126. 2 ± 2. 6 Ma with a 95% reliability, the Sm-Nd isochron age of scheelite is 121±11 Ma with a 95% reliability, and the Rb-Sr isochron age of quartz is 128 ±3 Ma with a 95% reliability. These data suggest that the mineralization epoch is coupled with the emplacement of the granite magma in this area. This kind of scheelite deposits is the products of the late Yannan magmatic activity, together with porphyry tin deposits and associated niobium-tantalum deposits in this area at the same epoch.