南祁连扎子沟埃达克岩年代学、地球化学特征及地质意义  

Geochronological and Geochemical Characteristics of the Zhazigou Adakite in South Qilian and the Geological Significance

作　　者：王亮 王凯 张翔[3] 黄增保[3] 杨涛[3] 梁凯鹏[3] 胡妍 刘子锐[3] WANG Liang;WANG Kai;ZHANG Xiang;HUANG Zengbao;YANG Tao;LIANG Kaipeng;HU Yan;LIU Zirui(Geological Exploration Fund Management Center of Gansu Province, Lanzhou 730000, Gansu, China;Department of Natural Resources of Gansu Province, Lanzhou 730000, Gansu, China;Geological Survey of Gansu Province, Lanzhou 730000, Gansu, China)

机构地区：[1]甘肃省地质勘查基金管理中心,甘肃兰州730000 [2]甘肃省自然资源厅,甘肃兰州730000 [3]甘肃省地质调查院,甘肃兰州730000

出　　处：《西北地质》2022年第1期39-49,共11页Northwestern Geology

基　　金：中国地质调查局“甘肃省五个泉子达坂大道尔基地区矿产远景调查”(1212010781070)。

摘　　要：扎子沟岩体位于南祁连西段党河南山,由石英闪长岩和花岗闪长岩组成。利用LAICPMS锆石U-Pb法测得花岗闪长岩年龄(450±12)Ma(MSWD=0.23,n=24),侵位时代为晚奥陶世。岩石主量元素显示,SiO2介于58.46%~69.14%,Al2O3介于13.70%~16.6%,MgO介于1.43%~4.31%,属高钾钙碱性准铝质花岗岩;微量元素富集轻稀土和Ba、Rb、Th、U、Sr等大离子亲石元素,相对亏损Nb、Ta、Ti、P等高场强元素和重稀土元素。其中,Sr含量介于130.0×10^(-6)~460.0×10^(-6),平均为310.93×10^(-6),Yb介于0.70×10^(-6)~1.81×10^(-6),平均为1.26×10^(-6),Y介于6.44×10^(-6)~17.68×10^(-6),平均为12.96×10^(-6),弱负Eu异常正Eu异常(δEu=0.77~1.55),具较高的Sr/Y值(20.2~37.1),具有埃达克岩地球化学特征。结合区域地质背景,认为岩体形成于陆陆碰撞环境,可能与晚奥陶世南祁连洋闭合,两侧欧龙布鲁克地块和中祁连地块发生碰撞导致地壳加厚拆沉,地幔物质上涌诱发下地壳部分熔融有关。Zhazigou batholith,which is composed of quartz diorite and granodiorite,is located in Danghenanshan of South Qilian.The LA-ICP-MS and zircon U-Pb age of the granodiorite is(450±12)Ma(MSWD=0.23,n=24),and the emplacement age is late Ordovician.The major elements show that SiO2 is 58.46%~69.14%,Al2O3 is 13.70%~16.6%,and MgO is 1.43%~4.31%,belonging to High-K calc-alkaline quasi-aluminous granite.Trace elements are rich in light rare earth and large ion lithophile elements such as Rb,Ba,Th,U,Sr,and depleted in heavy rare earth and high field strength elements such as Nb,Ta,Ti,P.The content of Sr is 130.0×10^(-6)~460.0×10^(-6) with an average content of 310.93×10^(-6);the content of Yb is 0.7×10^(-6)~1.81×10^(-6) with an average content of 1.26×10^(-6).The content of Y is 6.44×10^(-6)~17.68×10^(-6) with an average content of 12.96×10^(-6),weak to positive Eu anomaly(δEu=0.77~1.55)and higher Sr/Y ratio(20.2~37.1),having adakite characteristics geochemically.Combined with the regional geological background,it is believed that Zhazigou batholith formed in the continental collision environment,which was related to the close of south Qilian ocean in the Late Ordovician.The collision of the Oulongbuluke block and the middle Qilian block caused the thickening of the crust and the delamination.Then the hot mantle material upwelled leading to the partial melting of the lower crust.

关 键 词：南祁连 晚奥陶世 锆石U-PB年龄 埃达克岩 

分 类 号：P588.121[天文地球—岩石学]