西天山哈勒尕提含矿花岗岩地球化学、锆石U-Pb年代学及地质意义

摘要

The Halegati ore-bearing granitoids in West Tianshan is located in West Tianshan tectonic belt between Jung-gar and Erie block, which is composed of diorite, granodiorite and monzogranite.LA-ICP-MS zircon U-Pb age of monzo-granite is(357.9±1.3)Ma,belongs to Late Devonian.Diorite and granodiorite are characterized by K-poor,Na-rich and weakly peraluminous, which belong to I-type granite, while monzogranites are relatively K-rich, Na-poor and are S-type granite. The intrusive contact relationship and petrochemical compositions indicate that diorite and monzogranite aren’t derived from comagma by fractional crystallization and they may represent the stratified melting and penetrating in suc-cession of the felsic-mafic granulites phase in lower crust.Combined with regional evolutionary history,the Halegati ore-bearing granitoids in West Tianshan should be formed in the continental margin arc and the mechanism is partial melting of the lower crust caused by mantle uplift near subduction zone.%西天山哈勒尕提含矿花岗岩体位于准噶尔和伊犁地块间的西天山构造带内，其中赋含矽卡岩型铁铜矿床。岩体由闪长岩、花岗闪长岩和二长花岗岩组成。二长花岗岩LA-ICP-MS锆石U-Pb年龄为（357.9±1.3）Ma，时代为晚泥盆世。岩石地球化学特征表明，闪长岩和花岗闪长岩属贫钾富钠准铝质的I型花岗岩，二长花岗岩类则属贫钠富钾的过铝质S型花岗岩。岩相接触关系、地球化学特征表明，其不是同源岩浆分异结晶的产物，应源于长英质-基性麻粒岩相下地壳的分层熔融和先后侵入形成的。结合区域演化历史，西天山哈勒尕提含矿花岗岩体形成于大陆边缘弧环境，地幔动力学为靠俯冲带陆一侧的地幔上隆引起下地壳局部熔融和有少量地幔物质加入的模式。