关于含柯石英锆石SHRIMP测年获得大别-苏鲁超高压变质带超高压变质作用年龄的讨论  

A DISCUSSION ON UHPM AGES OF THE DABIE-SULU UHPM BELT BY SHRIMP U-Pb DATING OF COESITE-BEARING ZIRCONS

作　　者：张希道 宋明春 王仁民[2] 张华锋[3] 

机构地区：[1]山东省第四地质矿产勘查院,山东潍坊261021 [2]北京大学地质学系,北京100871 [3]中国科学院地质与地球物理研究所,北京100029

出　　处：《矿物岩石》2005年第1期30-37,共8页Mineralogy and Petrology

基　　金：国土资源大调查1:25×104日照等幅区域地质调查基金项目(200130000513号);1:50×104大别造山带编图项目

摘　　要：　对大别-苏鲁超高压变质(UHPM)带部分含柯石英包体的锆石及部分进行SHRIMPU-Pb测年的锆石进行划分和讨论后得出为大别-苏鲁UHPM带超高压变质作用(UHPM)年龄而进行含柯石英锆石SHRIMPU-Pb测年,宜从有结晶环带且在环带域或环带核部有柯石英包体的锆石的核部或环带域进行SHRIMPU-Pb测年,不宜从锆石边部获得UHPM年龄。着重讨论杨经绥等(2002)的两颗含柯石英锆石的结构,柯石英包体所在部位,测年数据的意义,得出苏鲁UHPM带UHPM年龄是578Ma(或略大于578Ma)。且这一认识与苏鲁UHPM带内区域地质情况相吻和。锆石中(多在边部)给出的印支期年龄值反映印支期地质作用(流体改造、重结晶等)改造事件的时代。This paper discussed part of the coesite-bearing zircons and SHRIMP U-Pb dating zircons of Dabie-Sulu ultrahigh pressure metamorphic (UHPM)belt.Suggesti on was made that it was suitable to obtain ultrahigh pressure metamorphism(UHPM)ages by SHRIMP U-Pb dating from the growth zone domains and the cores of the zones of the zircons,where coesite inclusions occurred,and it was not suitable to obtain UHPM ages from the outer peripheral parts of the zircons.The texture the position of the coesite inclusions,and the age values within two coesite-bearing zircons reported by Yang Jingsui et al(2002) were discussed in detail.The UHPM age of 578 Ma(or a little more than 578 Ma) in Dabie-Sulu UHPM belt was coincidental with the regional geological circumstances in Sulu UHPM belt.The age values of the Indosinian epoch dated from zircons from the outer peripheral partsed represent the time of late event modified by the Indosinian geological action (fluid modification,recrystallization etc).

关 键 词：柯石英 锆石 测年 SHRIMP 超高压变质作用 大别-苏鲁 包体 重结晶 改造 流体 

分 类 号：P588[天文地球—岩石学] P597[天文地球—地质学]