极地研究2016，Vol.28Issue(2)：159-180,22.DOI:10.13679/j.jdyj.2016.2.159
东南极格罗夫山地区冰碛石碎石带中高压麻粒岩和正片麻岩的锆石年代学研究及其构造意义
U-Pb ZIRCON CHRONOLOGY OF HIGH-PRESSURE GRANULITES AND ORTHOGNEISSES FROM GLACIAL MORAINES IN THE GROVE MOUNTAINS,EAST ANTARCTICA
摘要
Abstract
High-pressure granulites and orthogneisses from glacial moraines in the Grove Mountains,East Antarctica, were collected for zircon U-Pb isotope analysis.The zircon grains from four high-pressure granulites were mostly of metamorphic origin.However,some contained an inherited core aged 2633—2502 Ma.The metamorphic zircons showed two age stages (~570 Ma and ~555—545 Ma representing the earlier prograde and peak HP metamor-phism ages,respectively)and displayed flat HREE patterns in the chondrite-normalized REE diagram.The zircon grains from two orthogneisses typically showed a magmatic core with oscillatory zoning and a metamorphic rim with-out zoning.Different protolith ages were obtained from zircon cores of these two orthogneisses.An upper intercept age of 1 060 ±40 Ma was obtained from the cores of zircon in one sample,suggesting that its protolith came from the subglacial highlands in the southeast Grove Mountains.Analytical spots from another sample yielded a protolith age of 91 7 ±4 Ma,consistent with the protolith ages obtained for orthogneisses and mafic granulites that crop out in the Grove Mountains.The analytical spots from zircon rims from the two orthogneisses yielded similar metamorphic ages of ~530 Ma,in agreement with the time of retrograde metamorphism of high-pressure granulites reported previous-ly.High-pressure granulites were common in glacial moraines from the Grove Mountains,reflecting their wide-spread occurrence in the subglacial highlands.Moreover,U-Pb zircon dating confirmed that the subglacial high-lands of the Grove Mountains underwent a single Pan-African metamorphic cycle,but there was no evidence of a Grenville-age metamorphic event.关键词
东南极/格罗夫山/冰碛石/锆石U-Pb定年/泛非期变质作用Key words
East Antarctica/Grove Mountains/moraines/zircon U-Pb dating/Pan-African metamorphism引用本文复制引用
王伟,刘晓春,赵越,郑光高,陈龙耀..东南极格罗夫山地区冰碛石碎石带中高压麻粒岩和正片麻岩的锆石年代学研究及其构造意义[J].极地研究,2016,28(2):159-180,22.基金项目
国家海洋局“南北极环境综合考察与评估”专项（CHINARE 2015-02-05）、国家自然科学基金项目（41530209）和国土资源大调查项目（12120113019000）资助 （）
