华北中部狐偃山杂岩体形成时代研究——来自榍石U-Pb同位素年代学的证据  

Chronology Framework of Huyanshan Complex in Central North China Craton:Evidence from U-Pb Dating of Titanite

作　　者：何佳佳 张乔 靳梦琪 周俊林[2,3] 李玉宏 陈高潮[2,3] HE Jiajia;ZHANG Qiao;JIN Mengqi;ZHOU Junlin;LI Yuhong;CHEN Gaochao(Xi’an Urban Development(Group) Co.,Ltd., Xi’an 710004,Shaanxi,China;Key Laboratory for the Study of Focused Magmatism and Giant Ore Deposits, MNR, Xi’an Center of China Geological Survey, Xi’an 710054,Shaanxi,China;Northwest Geological Survey Science and Technology Innovation Center, Xi’an, 710054,Shaanxi,China)

机构地区：[1]西安城市发展(集团)有限公司,陕西西安710004 [2]自然资源部岩浆作用成矿与找矿重点实验室,中国地质调查局西安地质调查中心,陕西西安710054 [3]西北地质调查科技创新中心,陕西西安710054

出　　处：《西北地质》2022年第1期50-63,共14页Northwestern Geology

基　　金：陕西省科技计划项目“基于UThPb同位素年代学方法计算华山岩体中氦气资源量”(2021JQ327);中国地质调查局地质调查项目“关中地区氦气资源调查”(DD20190103);陕西省创新人才推进计划“造山带地层层序恢复:以甘蒙北山造山带南部的石炭—二叠系为例”(2021KJXX74)。

摘　　要：近年随着定年技术的发展,榍石LA-ICP-MS U-Pb定年法逐渐被学者采用,用来揭示某些特殊岩石类型的形成时代,如碱性岩。华北中部狐偃山碱性杂岩体由多个侵入体组成,岩性主要为二长岩类,岩石中发育大量继承锆石,结晶锆石相对较少,但包含大量岩浆榍石。本次研究即利用榍石LA-ICP-MS U-Pb定年法,对研究相对薄弱的矿泉、狼窝沟2个二长岩体中榍石进行了年代学分析。结果表明这2个二长岩体分别侵位于129 Ma和130 Ma。作为对比,同时对相同2个样品进行了锆石LA-ICP-MS U-Pb定年,2种方法得到的结果在误差范围内一致。结合前人研究资料,狐偃山杂岩体主体二长岩类侵位于早白垩世早期(127~131 Ma),早白垩世晚期(111~114 Ma)有少量正长岩形成,从而构成了狐偃山杂岩体。With the development of dating technique,LA-ICP-MS U-Pb dating of titanite has been applied to some special rock types such as alkaline rocks.The Huyanshan alkaline complex was composed of several plutons;the major lithology was monzonite with abundant inherited zircons and magmatic titanites,and little crystallized zircons.This study analyzed chronologically the two monzonites of Kuangquan and Langwogou based on the LA-ICP-MS U-Pb dating of titanite.Results show that the two were emplaced at 129~130Ma.Meanwhile zircon LA-ICP-MS U-Pb dating was conducted on the same two samples as a contrast.The two dating techniques are consistent within the error range.According to previous studies,Monzonites of the main part of Huyanshan complex were emplaced in the early Early Cretaceous(127~131 Ma),while small amount of syenites were formed in the late Early Cretaceous(111~114 Ma),eventually forming the Huyanshan complex.

关 键 词：二长岩 LA-ICP-MS 榍石 狐偃山 华北中部 

分 类 号：P581[天文地球—岩石学]