湖南彭公庙岩体地球化学特征、时代及钨锡成矿潜力

南岭成矿带加里东期大花岗岩基的钨锡成矿潜力是近年来地质学家关注的热点。本文以湖南省彭公庙岩体为研究对象，精确厘定了产于彭公庙岩体内部的石牛仙钨矿的形成时代，同时厘定了彭公庙岩体中粗粒黑云母花岗闪长岩形成时代，分析了其地球化学特征，并与典型的成钨锡矿花岗岩进行对比，以此评估其钨锡成矿潜力。黑云母花岗闪长岩LA-ICP-MS锆石和独居石U-Pb年龄分别为436.1±2.5 Ma(MSWD=1.9,n=19)和436.8±2.8 Ma(MSWD=2.7,n=20),指示其侵位于早志留世。石牛仙钨矿床白云母³⁹Ar/⁴⁰Ar同位素坪年龄为150.2±1.2 Ma(MSWD=0.42),成矿时代与彭公庙成岩时代明显不同。彭公庙岩体分异程度不高，成矿元素W和Sn含量低，主要来源于上地壳贫粘土的变质砂岩，与南岭典型的成钨、成锡花岗岩分异程度高、成矿元素含量高、来源于富粘土的上地壳物质部分熔融区别明显，说明其成矿潜力有限。最后，在综合前人研究成果的基础之上，指出应综合地球物理、地球化学、构造蚀变信息等资料，重点评价彭公庙岩体内部及周缘晚期晚侏罗世花岗岩岩脉或...

Geochemical characteristics, age and W-Sn metallogenic potential of Penggongmiao pluton, Hunan Province

In recent years, geologists have paid more and more attention to the potential of tungsten and tin metallogenic of Caledonian batholith in Nanling metallogenic belt. In order to evaluate the tungsten and tin metallogenic potential of the Penggongmiao pluton in Hunan Province, mineralization age of the Shiniuxian tungsten deposit, diagenetic age and geochemical characteristics of biotite granodiorite from the Penggongmiao pluton are analyzed in this paper. The LA-ICP-MS zircon and monazite U-Pb ages of the coarse-grained biotite granodiorite of the Penggongmiao pluton are 436.1±2.5 Ma (MSWD=1.9, n=19) and 436.8±2.8 Ma (MSWD=2.7, n=20), respectively, while the muscovite ³⁹Ar/⁴⁰Ar isotopic dating of the Shiniuxian tungsten deposit has a plateau age of 150.2±1.2 Ma (MSWD=0.42). The results show that the diagenesis of rocks occurred in Early Silurian, while the mineralization of tungsten is dated to late Jurassic, and there are the products of different magmatic activities. Compared to the typical tungsten-tin granite in Nanling metallogenic belt, the Penggongmiao granite has low degree of differentiation and low content of ore-forming elements. In addition, the Penggongmiao granites are mainly derived from the poor-clay metasandstone of the upper crust, while the typical tungsten-tin granites are usually derived from the rich-clay of the upper crust material. The above evidences indicate that the mineralization potential of the Caledonian Penggongmiao pluton is limited. Finally, on the basis of comprehensive previous research results, the authors point out that the metallogenic potential of the Late Jurassic granite dikes or stocks in and around the Penggongmiao batholith should be evaluated by integrating geophysical, geochemical, structural and alteration information.