南秦岭太白河地区石英二长闪长岩锆石U-Pb同位素年代学、地球化学及其地质意义  

Zircon U-Pb Isotopic Geochronology,Bulk Geochemistry and Their Geological Significance of the Quartz Monzodiorite from the Taibaihe Region in the South Qinling Orogen

作　　者：王瑞廷 李青锋 秦西社 张斌 王博闻 冀月飞 WANG Ruiting;LI Qingfeng;QIN Xishe;ZHANG Bin;WANG Bowen;JI Yuefei(Northwest Nonferrous Geological and Mining Group Co.,Ltd.,Xi’an,Shaanxi 710054,China;Shaanxi Engineering Technology Research Center of Comprehensive Utilization of Mineral Resources,Xi’an,Shaanxi 710054,China;Baoji No.717 Corps Limited of Northwest Nonferrous Geological and Mining Group,Baoji,Shaanxi 721015,China)

机构地区：[1]西北有色地质矿业集团有限公司,陕西西安710054 [2]陕西省矿产资源综合利用工程技术研究中心,陕西西安710054 [3]宝鸡西北有色七一七总队有限公司,陕西宝鸡721015

出　　处：《现代地质》2023年第3期562-572,共11页Geoscience

基　　金：中国地质调查局项目“秦岭成矿带文康—凤太地区地质矿产质调查”(DD20160014)。

摘　　要：为查明南秦岭太白河地区中性岩体的形成时代、岩石成因、源区性质和构造背景,本研究选取该地区石英二长闪长岩进行了锆石U-Pb同位素年代学和全岩元素组成研究。LA-ICP-MS锆石U-Pb同位素年龄测试结果显示,^(206)Pb/^(238)U加权平均年龄为(216.8±2.2)Ma(MSWD=1.15,n=20),指示石英二长闪长岩形成时代为晚三叠世。岩石元素地球化学结果表现出K、Rb等大离子亲石元素和Zr、Hf等高场强元素相对富集,Nb、Ta、P、Ti相对亏损,呈现轻稀土元素强烈富集的右倾型稀土配分模式,具轻微的负Eu异常,为准铝质高钾钙碱性系列岩石。岩浆物质来源具有壳幔混合的特点。基于区域地质构造演化特征,认为太白河地区石英二长闪长岩可能形成于碰撞-后碰撞阶段,属与邻近的西坝岩体同源岩浆活动的产物。结合区域岩浆作用、构造活动与成矿作用的研究认识,以及本文对有关年龄的修正与总结,认为区内凤太矿集区成矿作用时代为晚三叠世。In order to ascertain the formation time,petrogenesis,magma source and tectonic setting of the intermediate rocks in Taibaihe area of South Qinling,zircon U-Pb geochronology and geochemistry of the quartz monzodiorite have been studied in the thesis.The results of LA-ICP-MS zircon U-Pb gechronology show that the ^(206)Pb/^(238)U weighted mean age of quartz monzodioirte is(216.8±2.2)Ma(MSWD=1.15,n=20),indicating that it was formed in the Late Triassic.According to the lithogeochemistry studies,the quartz monzodioirte belongs to the aluminum unsaturate and high potassium calc-alkaline series.This suite of rocks are rich in LILE(such as K,Rb)and HFSE(such as Zr,Hf),and relatively depleted in Nb,Ta,P,and Ti.The quartz monzodiorite is rich in LREE and poor in HREE,with slightly negative Eu anomalies.The magma source has the characteristics of crust-mantle mixed molten.Based on the tectonic evolution of the South Qinling Orogen,we consider that the Taibaihe quartz monzodioirte may be formed in the syn-collisional to post-collisional stage of the orogeny,belonging to the product of same homologous magmatism activity as Xiba granites.According to the previous studies of regional magmatism,tectonic activity and mineralization,and the new work of magmatic-metallogenic ages modification in our study,it is considered that the metallogenic age of Fengtai ore cluster region is Late Triassic.

关 键 词：锆石U-PB年龄 地球化学 石英二长闪长岩 南秦岭 太白河 

分 类 号：P588.12[天文地球—岩石学] P595[天文地球—地质学] P597.3