新疆北部额尔齐斯构造带434Ma埃达克质岩的确立及地质意义  

The Early Paleozoic Adakitic Intrusive Rocks of Erqisi Tectonic Belt in Northern Xinjiang

作　　者：秦纪华[1] 周刚[2] 张立武[1] 董连慧[2] 李永 赵忠合[1] 何立新[1] 

机构地区：[1]新疆维吾尔自治区地质矿产勘查开发局第四地质大队,新疆阿勒泰836500 [2]新疆维吾尔自治区地质矿产勘查开发局,新疆乌鲁木齐830000 [3]新疆有色地勘局地质勘查院,新疆乌鲁木齐830000

出　　处：《新疆地质》2014年第4期425-433,共9页Xinjiang Geology

摘　　要：额尔齐斯构造带中萨勒巴斯岩体主要由糜棱岩化石英闪长岩和英云闪长岩组成,锆石U-Pb SHRIMP年龄为（434±10）Ma,Si O2含量60.17%-65.52%,Al2O3含量较高,富Na、贫K,Y,Yb等,Sr含量较高,Sr/Y值较高,轻稀土明显富集。该岩体具正的铕异常或微弱负铕异常;具明显的Nb,Ta,Ti负异常和Sr正异常;具低的Sr初始值、高的εNd（T）值及较年轻的Nd模式年龄。该岩体具与典型埃达克岩相似的地球化学特征,岩浆来源于俯冲板片熔融,具较低的Mg#（40-44）及Cr,Co,Ni含量,表明其未与地幔发生明显的相互作用,形成环境属活动大陆边缘或陆缘弧。埃达克质侵入岩的发现,为古亚洲洋在早古生代向西伯利亚板块俯冲提供了较直接的岩石学证据,为额尔齐斯构造带内及北侧寻找斑岩型铜、金矿提供了可能。The Salebasi pluton is mainly composed by mylonitized quartz diorite and tonalite rocks in Erqisi tectonic belt,the zircon SHRIMP U-Pb age is 434±10Ma. The content of SiO2 in the pluton is 60.17%-65.52%,higher Al2O3、Sr and Sr/Y,enriched in Na and LREE ,depleted in K、Y、Yb,has positive Eu anomaly or slightly negative Eu anomaly,has visible positive Nb、Ta、Ti anomaly and negative Sr anomaly. The Salebasi pluton is geochemically similar to adakite,e. g.,lower Sr initial value、higherεNd（T） and younger Nd model ages. The Salebasi pluton magma derived from subducted slab melting, it have lower contents of Mg^#（40-44）and Cr、Co、Ni, indicates that it is not occurred obvious interaction with the mantle. The Salebasi pluton formation environment belongs to an active continental margin or continental margin arc, the discovery of this adakitic intrusive rocks provides a direct petrology evidence that the ancient Asian Ocean subduct to Siberia in the early Paleozoic,and also provides possibility to find porphyry copper and porphyry gold in the north of the Erqisi tectonic belt.

关 键 词：新疆北部 额尔齐斯构造带 早志留世 埃达克质岩 

分 类 号：P588.12[天文地球—岩石学]