西藏浦桑果铜多金属矿床侵入岩的地球化学特征及对构造环境的约束  

Geochemical Characteristics of Intrusive Rocks in the Pusangguo Copper-Polymetallic Deposit,Tibet:Constraints on Tectonic Setting

作　　者：崔晓亮[1] 多吉 刘鸿飞 张金树 刘婷婷[1] 粟登逵 普布次仁 杜刚强 刘祖军 

机构地区：[1]成都理工大学地球科学学院,四川成都610059 [2]西藏地质矿产勘查开发局,西藏拉萨850000 [3]西藏自治区地质调查院,西藏拉萨850000 [4]西藏地质矿产勘查开发局第六地质大队,西藏拉萨851400

出　　处：《地球学报》2012年第4期537-545,共9页Acta Geoscientica Sinica

基　　金：中国地质调查局项目"西藏大型矿床成矿专属性研究"(编号:1212011221073);成都地质调查中心项目"西藏冈底斯成矿带构造岩浆演化与成矿作用研究"(编码:1212010818098)联合资助

摘　　要：浦桑果铜多金属矿床是在南木林火山盆地内新近发现的矽卡岩型铜多金属矿床。文章对矿区内的花岗闪长岩、花岗闪长斑岩和闪长玢岩进行了岩石地球化学研究,结果表明:这些岩石的ω(SiO2)介于59.08%～67.28%,ω(Al2O3)为15.38%～16.86%,ω(MgO)为1.52%～4.06%,ω(TFeO)介于1.2%～3.46%,均属钙碱性系列。稀土元素总量为22.0×10-6～148.56×10-6,LaN/YbN比值为17.98～37.57,为轻稀土元素富集。花岗闪长岩、花岗闪长斑岩和闪长玢岩均相对富集Cs、Rb、Sr等大离子亲石元素(LILE),亏损高场强元素(HFSE)Th、U、Nb等,强负铕异常或弱负铕异常,无铈异常或弱铈异常。岩石学、岩石化学、微量元素研究表明,花岗闪长斑岩和闪长玢岩形成于中生代雅鲁藏布新特提斯洋向北部拉萨地体俯冲的岛弧环境,花岗闪长岩形成于青藏高原碰撞后伸展作用环境。The Pusangguo copper-polymetallic deposit is located in Nanmulin volcanic basin. Petrographic and geochemical studies of granodiorite, granodiorite-porphyry and diorite-porphyrite show that the intrusive rocks are of calc-alkaline series, with ω（SiO3） ranging from 59.08% to 67.28%, ω（Al2O3） ranging from 15.38% to 16.86% ω（MgO） ranging from 1.52% to 4.06%, and co（TFeO） ranging from 1.2% to 3.46%. Total REE concentrations range from 22.0x106 to 148.56x10-6, LaN/YbN ratios vary from 17.98 to 37.57, with the enrichment of LREE. Granodiorite, granodiorite-porphyry and diorite-porphyrite are enriched with LILE elements such as Cs, Rb and Sr and depleted in HFSE elements such as Th, U and Nb, with weak or intensely negative Eu anomalies and no or weak Ce anomalous features. Petrographic and geochemical studies indicate that granodiorite-porphyry and diorite-porphyrite were produced by Tethys subduction towards North Lhasa tectonic body, and granodiorite was formed in an extension setting of post-collision in Tibet Plateau.

关 键 词：铜多金属矿床 侵入岩 地球化学 构造环境 约束 

分 类 号：P618.4[天文地球—矿床学] P588.13[天文地球—地质学]