新疆西天山莫斯早特石英钠长斑岩铜矿床——一个与埃达克质岩石有关的铜矿实例  

A case study on porphyry Cu deposit related with adakitic quartz albite porphyry in Mosizaote, Western Tianshan, Xinjiang, China.

作　　者：赵振华[1] 熊小林[1] 王强[1] 白正华[1] 梅厚均[1] 

机构地区：[1]中国科学院广州地球化学研究所,广州510640

出　　处：《岩石学报》2004年第2期249-258,共10页Acta Petrologica Sinica

基　　金：国家重点基础研究计划(2001CB409803);国家"305"96-915-03-02;国家攀登计划预选项目(95-预-25)资助.

摘　　要：与埃达克岩石有关,在环太平洋地区发现了大型、超大型斑岩型铜矿床。本文提供了一个产于中亚成矿域新疆西天山的莫斯早特铜矿床研究的实例。含矿岩体为石英钠长斑岩,岩体主量、微量元素地球化学特点与埃达克质岩石一致:富Na、Al;高Sr,低Y;Sr/Y>40,亏损HREE;La/Yb>20;Eu为正异常(δEu/Eu*为～1.27)。全岩40Ar/39Ar年龄268±5Ma,Rb-Sr年龄248±12Ma,K-Ar年龄254.5Ma,属中晚二叠世。矿体呈脉状、网脉状;围岩蚀变为绿帘石化、青盘岩化和黄铁矿化。铜品位1％-5％,主要工业矿物为辉铜矿、斑铜矿。矿石富含Ag(5.35-240μg/g)、Pb(0.01％～0.16％)、Zn(0.26％一2.40％)、Au(0.02～0.16μg/g)。矿石矿物S同位素δ34S为-6.0‰～5.81‰,平均-0.28‰;辉铜矿、斑铜矿和孔雀石的207Pb/204Pb为15.46～15.77,206Pb,/204Pb为18.01-18.42,属造山带与地幔Pb之间;矿石矿物包裹体的δ18O-2.54‰～-8.11‰,δDH2O-68.9‰～-98.8‰,属岩浆水与大气降水之混合。矿石矿物的(87Sr/86Sr);为0.70596,(143NcL/146Nd).为0.512403,εNd(t)为+1.5,其Sr-Nd同位素组成及同位素年龄与含矿埃达克质石英钠长斑岩一致。含矿埃达克质石英钠长斑岩形成于后碰撞阶段,属由碰撞、挤压向伸展、拉张转变的构造动力学格架转折期。埃达克岩浆的较高温度?Some large or giant porphyry Cu deposits related with adakite are widely spreaded around the sircum-pacific area. This paper provides a case study on Cu deposit related with adakitic quartz albite porphyry in central Asia metallogenic province. The Mosizaote quartz albite porphyry possesses similar geochemical features of mayjor and trace elements with metallogenic adakites in the world, such as rich in Na and Al; high contents of Sr and low contents of Y, Sr/Y > 40; depleted in HREE, La/Yb > 20; rich in Eu ( deltaEu/Eu * 1.15 similar to 1.27). The isotopic ages for the quartz albite porphyry are 268 +/- 5 Ma (Ar-40/Ar-39), 248 +/- 12Ma ( Rb-Sr) and 254.5 Ma ( K-Ar) respectively. The ore bodies are mainly in the forms of veins and network veins. Epidotization, propylitization and pyritization are the dominante alteration in the wall rocks. Chalcocite and bornite are the main industrial minerals. The ores are rich in Ag (5.35 similar to 240 mug/g), Ph (0.01 % similar to 0.16%), Zn (0.26% similar to 2.40%) and Au (0.02 similar to 0.16 mug). The isotopic compositions of O and H for the inclusions of chalecocite, bornite and malaehite are: (delta(18)O - 2.54%, similar to 8.11%, deltaD(H2O)), 20 - 68.9parts per thousand similar to -98.8%o. The isotopic compositions of S and Ph for these Cu minerals are: delta(34)S - 6.0parts per thousand similar to 5.81parts per thousand - 0.28parts per thousand and (207)pb/Pb-204 15.46 similar to 15.77, (206)pb/Pb-204 18.01 similar to 18.42, indicating the deep source of the metallogenic materials. Close relationship between the Cu mineralization and adakitic quartz albite porphyry can also be found from their similar isotopic compositions of Sr and Nd, such as (Sr-87/Sr-86)(i) 0.70596, (Nd-134/Nd-146)(i) 0.512403 and epsilon(Nd) (t) + 1.5 and the isochron ages of Sm-Nd(243Ma) for the Cu minerals in the Mosizaote Cu deposit. The Mosizaote adakitic quartz albite porphyry was generated in the post-collision stage: a significant turn of regional tectonodynamic framework from collision c

关 键 词：埃达克岩 斑岩铜矿床 新疆西天山 

分 类 号：P588.13[天文地球—岩石学] P618.41[天文地球—地质学]