赣南狮吼山硫铁多金属矿区花岗岩地球化学、年代学特征及其成因

狮吼山矿区是江西省内规模最大的矽卡岩型硫铁多金属矿床，伴生W、Cu、Au多种成矿元素，成矿作用与矿区出露的茶山迳复式花岗岩体有关。岩体主要包括茶山迳似斑状黑云母二长花岗岩和莲湖细粒二长花岗岩两期，为研究成矿岩体的侵位时代、岩石成因及与成矿的关系，本次工作进行了U-Pb锆石定年、岩相学和岩石地球化学等测试分析。结果表明：岩体具有高硅、高钾、富铝的特征，属高钾钙碱性系列花岗岩；轻重稀土元素分馏明显，均为右倾型，弱Eu负异常，以富集Cs、Rb、Th、U、Pb，亏损Ba、Nb、Sr、和Ti等元素为主要特征，属于低Ba-Sr壳源花岗岩类；锆石具较好晶形，具典型岩浆锆石特征，利用LA-ICP-MS进行U-Pb测年，获得谐和年龄为（162.4±0.6）Ma（MSWD=1.8），加权平均年龄为（162.4±1.4）Ma（MSWD=1.4），谐和年龄与加权平均年龄在误差范围内高度一致，表明茶山迳复式岩体侵位于燕山早期中侏罗世；综合考虑岩体矿物组合、主微量元素及高分异特征，认为其成因分类应属于S型花岗岩；对比中国花岗岩成矿元素平均含量，茶山迳两期花岗岩均具有较高的W、Mo、Bi、Pb等成矿元素含量，可同时为成矿作用提供热源、流体及物质。

Geochemistry,Geochronology and Genesis of Granites in Shihuoshan Pyrite Polymetallic Ore Area,South Jiangxi Province

Shihoushan ore deposit is the largest skarn-type pyrite polymetallic ore deposit in Jiangxi Province,which is associated with tungsten, copper and gold ore-forming elements, and related to the nearby Chashanjing composite granites. The granites mainly include two periods: Chashanjing porphyritic biotite monzonitic granite and Lianhu fine monzonitic granite. In order to study the emplacement age, petrogenesis,and relationship with mineralization, the U-Pb zircon dating, petrography,and rock geochemistry were tested and analyzed. The results show that the intrusive rocks are characterized by high silicon, potassium, and aluminum, belonging to the high-K calc-alkaline series granites; the fractionation of rare earth elements is obvious in right-wing type, with weak Eu negative anomaly, enrichment of Cs, Rb, Th, U and Pb, depletion of Ba, Nb, Sr and Ti, the feature of low Ba-Sr crust derived granites. The U-Pb zircon dating by LA-ICP-MS yields the concordant age of (162.4 ±0.6) Ma (MSWD=1.8), and the weighted average age of (162.4 ±1.4) Ma (MSWD=1.4), these two are highly consistent within the error range, which implies that the Chashanjing composite granite was emplaced in Middle Jurassic of Early Yanshanianan. Considering the mineral assemblage, major and trace elements and high fractionation characteristics, it is considered that the rock mass belongs to S-type granite. In comparison with ordinary Chinese granites, Chashanjing granites are obviously rich in metallogenic elements such as W, Mo, Bi, and Pb, which might have provided heat, fluid, and material for the mineralization.