内蒙古正镶白旗都比地区石英斑岩和花岗斑岩年代学、地球化学特征及岩石成因  

Geochronology,Geochemistry and Petrogenesis of Quartz Porphyry and Granite Porphyry in Dubi Area,Zhengxiangbai Banner,Inner Mongolia

作　　者：姚国华 胡乔青[1] 牛文林 赵元艺[1] Yao Guohua;Hu Qiaoqing;Niu Wenlin;Zhao Yuanyi(Institute of Mineral Resources,Chinese Academy of Geological Sciences/Key Laboratory of Metallogeny and Mineral Assessment,Mistry of Natural Resources,Beijing 100037,China;School of Earth Sciences and Resources,China University of Geosciences(Beijing),Beijing 100083,China;Inner Mongolia Nonferrous Geological Mining(Group)609 Co.,Ltd.,Ulanqab012001,Inner Mongolia,China)

机构地区：[1]中国地质科学院矿产资源研究所/自然资源部成矿作用与资源评价重点实验室,北京100037 [2]中国地质大学(北京)地球科学与资源学院,北京100083 [3]内蒙古有色地质矿业(集团)六○九有限责任公司,内蒙古乌兰察布012001

出　　处：《吉林大学学报（地球科学版）》2022年第3期899-916,共18页Journal of Jilin University：Earth Science Edition

基　　金：中央级公益性科研院所基本科研业务费专项资金项目(KK1928);正镶白旗同创矿业有限公司项目(HE1920)。

摘　　要：内蒙古正镶白旗都比地区石英斑岩脉和花岗斑岩脉位于华北板块北缘白乃庙岛弧带.本文采用LA ICP MS锆石U Pb定年方法,厘定石英斑岩和花岗斑岩的成岩年龄分别为(127.8±2.1)和(128.8±0.7)Ma,均为早白垩世岩浆活动产物.岩石地球化学特征显示,石英斑岩富硅(w(SiO_(2))为76.06%~77.20%)、富钾(w(K_(2) O)为4.66%~6.48%)、高TFeO/MgO值(10.42~12.55)、较高的10000Ga/Al值(2.71~3.27)、低w(CaO)(0.58%~0.70%)、w(Al2O3)为11.63%~12.67%、铝饱和指数(A/CNK)为1.08~1.15;花岗斑岩富硅(w(SiO_(2))为70.67%~71.88%)、富钾(w(K_(2)O)为5.83%~6.45%)、高TFeO/MgO值(10.91~12.10)、较高的10000Ga/Al值(2.64~3.03)、低w(CaO)(0.33%~0.44%)、w(Al2O3)为14.47%~15.14%、铝饱和指数为1.14~1.16;两者稀土元素配分曲线具有明显负铕异常和“海鸥型”右倾模式;两者相对富集Rb、Th、K、Zr、Hf等元素,相对亏损Sr、Ba、Ti、P等元素,显示铝质A型花岗岩特征.石英斑岩、花岗斑岩锆石εHf(t)值分别为-1.56~1.85、-0.87~2.14,二阶段模式年龄(TDM2)分别为1281~1067、1240~1046Ma,显示两者为壳幔物质混合作用的产物.结合区域构造演化,认为都比地区石英斑岩、花岗斑岩形成于板内伸展环境,是华北板块北缘早白垩世岩石圈减薄的产物.Quartz porphyry veins and granite porphyry veins are developed in the Dubi area of Zhengxiangbai Banner,Inner Mongolia,and are structurally located in the Bainaimiao island arc belt on the northern margin of the North China craton.Through LA-ICP-MS zircon U-Pb dating,the diagenetic ages of the quartz porphyry and granite porphyry are(127.8±2.1)and(128.8±0.7)Ma,respectively,and both are products of the Early Cretaceous magmatism.Petro-geochemically,the quartz porphyry is rich in silica(w(SiO_(2))76.06%-77.20%)and potassium(w(K_(2)O)4.66%-6.48%),high TFeO/MgO ratio(10.42-12.55),higher 10000 Ga/Al ratio(2.71-3.27),low w(CaO)(0.58%-0.70%).w(Al2O3)is 11.63%-12.67%,and the aluminum saturation index(A/CNK)is 1.08-1.15.The granite porphyry is rich in silica(w(SiO_(2))70.67%-71.88%)and potassium(w(K_(2)O)5.83%-6.45%),high TFeO/MgO ratio(10.91-12.10),higher 10000 Ga/Al ratio(2.64-3.03),and low w(CaO)(0.33%-0.44%).w(Al2O3)is 14.47%-15.14%,and the aluminum saturation index is 1.14-1.16.Their REE distribution curves show“seagull”right-leaning pattern with obvious negative Eu anomalies.They are relatively rich in Rb,Th,K,Zr,Hf etc.,and depleted in Sr,Ba,Ti,P,etc.,indicating the characteristics of aluminous A-type granite.The zirconεHf(t)values of quartz porphyry and granite porphyry are-1.56-1.85 and-0.87-2.14,respectively,and the two-stage model ages(TDM2)are 1281-1067 Ma and 1240-1046 Ma,respectively,indicating that the two rocks are the products of mixed materials from the crust and mantle.Combined with the regional tectonic evolution,it is considered that the quartz porphyry and granite porphyry were formed in the intraplate extensional environment during the thinning of the Early Cretaceous lithosphere on the northern margin of the North China craton.

关 键 词：年代学 地球化学 石英斑岩 花岗斑岩 都比地区 

分 类 号：P588.1[天文地球—岩石学] P59[天文地球—地质学]