东天山二叠纪大草滩地区镁铁-超镁铁质岩体的岩浆演化过程和含矿性  

Differentiation of magmas in the formation of Permian mafic-ultramafic intrusions in the Dacaotan area,Eastern Tianshan: Implications for Ni-Cu-( PGE) sulfide mineralization potentials

作　　者：任明浩[1,2] 王焰[3] 倪康 孙亚莉[1] 

机构地区：[1]同位素地球化学国家重点实验室、中国科学院广州地球化学研究所,广州510640 [2]中国科学院大学,北京100039 [3]中国科学院矿物学与成矿学重点实验室、中国科学院广州地球化学研究所,广州510640 [4]福建地质矿产局闽西地质大队,厦门361000

出　　处：《岩石学报》2013年第10期3473-3486,共14页Acta Petrologica Sinica

基　　金：国家973项目(2011CB808903);中国科学院知识创新工程重要方向项目(KZCX2-YW-JS103)联合资助

摘　　要：大草滩地区位于新疆东天山土墩一黄山一图拉尔根镁铁一超镁铁质岩带西侧，觉罗塔格构造带中段，区域构造环境主要受康古尔塔格-黄山深大断裂控制。本次研究的大草滩地区一、二号岩体形成于早二叠纪，SIMS法锆石U-Pb年龄分别为279±2Ma和278±2Ma。2个岩体主要由橄榄岩和辉长岩组成，全岩稀土总量较低，具LREE轻微亏损至平坦的分配型式。全岩Sr－Nd同位素与微量元素组成显示两个岩体的母岩浆来自软流圈地幔，其成分与N．MORB相似，在上升过程中经历了较低程度（1％～5％）的同生A型花岗岩混染。由于低程度的部分熔融（10％～15％）导致硫化物残留在地幔源区，导致母岩浆强烈亏损铂族元素，因此大草滩地区一、二号岩体可能不具有形成具经济价值铜镍硫化物矿床的潜力。The No. 1 and No. 2 mafic-uhramafic intrusions in the Dacaotan area located in the middle of Jueluotag suture zone and north of Kanggnertage-Huangshan fault. To the east of this area, a number of magmatic Ni-Cu-（PGE） sulfide deposits are hosted in the mafic and ultramafic intrusions in the Tudun-Huangshan-Tulargen areas, which occur in the south of Kanggnertage-Huangshan fault. Zircons from two gabbro samples of the No. 1 and No. 2 intrusions yield SIMS ^238206ges of 279± 2Ma and 278 ± 2Ma, respectively. The two intrusions mainly consist of dunite and gabbro and both have low rare earth elements （REE） concentrations, with slightly depleted to fiat LREE patterns. Whole-rock Sr-Nd isotopic compositions indicate that the parental magmas of the two intrusions may have derived from asthenosphere mantle and were similar to N-MORB in compositions. The parental magmas may have been contaminated by small amounts （1% ～% ） of the coeval A-type granite during ascent. Due to relatively low degrees of partial melting of the mantle source （ 10% ～15% ）, sulfides may be remained in the mantle source. The parental magmas therefore are PGE-depleted and it is little chance to find economic Ni-Cu-（PGE） sulfide deposits in these two intrusions.

关 键 词：二叠纪 东天山 镁铁-超镁铁质岩体 铜镍硫化物矿化 成矿潜力 

分 类 号：P588.125[天文地球—岩石学] P597.3[天文地球—地质学]