肖家营子钼铁矿床成矿物质来源——来自PGE元素和S同位素的证据  

Metal sources of Xiaojiayingzi Mo(Fe)deposit:Evidence from PGE and S isotope analyses

作　　者：代军治[1,2] 谢桂青[2] 王瑞廷 任涛 王涛 张西社 

机构地区：[1]西北有色地质勘查局地质勘查院,陕西西安710054 [2]中国地质科学院矿产资源研究所,北京100037 [3]西北有色地质勘查局七一三总队,陕西商洛726000

出　　处：《矿床地质》2013年第2期273-279,共7页Mineral Deposits

基　　金：国土资源大调查项目(编号:1212010634001);"十二五"国家科技支撑计划项目(编号:2011BAB04B05);公益性行业科研专项(编号:201111007-3)的联合资助

摘　　要：肖家营子矿床是一个与细粒闪长岩有关的矽卡岩型钼铁矿床。采用ICP-MS法对该矿床主要矿石矿物和围岩中的铂族元素进行分析表明:PGE元素在不同矿物中的含量变化较大,在辉钼矿和黄铁矿中比较富集,而在磁铁矿、石榴子石及细粒闪长岩、白云岩中则含量较低,这与PGE趋向在硫化物中富集的行为有关。不同矿物或岩石的原始地幔标准化曲线呈似W型,显示出Ir和Pt负异常,Ru正异常。辉钼矿和黄铁矿中的PGE分异较明显,具有相似的配分模式;磁铁矿、石榴子石、细粒闪长岩和白云岩内的PGE分异不明显,具有相近的IPGE配分模式。硫同位素分析结果显示,多数硫化物的δ34S值为3‰～5‰,与赋矿细粒闪长岩的δ34S值(1.1‰～3.5‰)较相似。PGE和硫同位素分析表明,肖家营子矿床不同成矿阶段成矿物质的来源不同,矽卡岩阶段的成矿物质主要来自细粒闪长岩和白云岩,热液硫化物阶段的成矿物质不全是来自细粒闪长岩和白云岩,还可能有壳幔混源物质的加入。The Xiaojiayingzi Mo （Fe） deposit is temporally and spatially associated with diorite, and the mineralization is hosted in skarn. Concentrations of platinum group elements （PGE） in various major ore minerals and host rocks of the Xiaojiayingzi deposit were analyzed by using the inductively coupled plasma mass spectrometry （ICP-MS）. The results show that the total PGE values in various samples vary greatly between 0.46×10-9 to 216×10-9. PGE is rich in molybdenum and pyrite and poor in magnetite, garnet, diorite and dolomite, suggesting that PGE tends to be concentrated in sulfides. The primary mantle-normalized PGE patterns of various samples show marked negative Ir and Pt and positive Ru anomalies. The molybdenum shows marked fractionation of PGE and is similar to the pyrite. The fractionation patterns of PGE in magnetite and garnet are characterized by weak PGE anomalies, similar to things of diorite and dolomite, suggesting that the metal sources were closely related to the diorite and dolomite. An analysis of S isotope of sulfides from the Xiaojiayingzi deposit indicates that the δ34S values of most sulfides from the Xiaojiayingzi deposit show a peak of 3‰~5‰, similar to things of diorite. Based on geological characteristics, PGE and S isotope of the Xiaojiayingzi deposit, the authors hold that different ore-forming stages had different metallogenic materials. The metallogenic materials of the skarn mineralization stage were derived mainly from the diorite and dolomite. The metallogenic materials of the hydrothermal sulfide stage were derived not only from the diorite and dolomite but also from the mixed crust-mantle system.

关 键 词：地球化学 硫化物 PGE 成矿物质来源 肖家营子 

分 类 号：P618.65[天文地球—矿床学] P618.31[天文地球—地质学]