东南极拉斯曼丘陵早古生代麻粒岩相变质事件——Sm-Nd同位素年代学证据  

EARLY PALEOZOIC EVENT OF LOW-PRESSURE GRANULITE FACIES METAMORPHISM IN THE LARSEMANN HILLS, EAST ANTARCTICA: EVIDENCE FROM Sm-Nd ISOTOPIC CHRONOLOGY

作　　者：赵越[1] 张宗清[1] 宋彪[1] 王彦斌[1] 刘小汉[2] 李继亮[2] 

机构地区：[1]中国地质科学院地质研究所,北京 100037 [2]中国科学院地质研究所,北京 100029

出　　处：《南极研究》1993年第2期52-56,共5页

基　　金：国家自然科学基金;地质行业基金;国家南极考察委员会资助项目

摘　　要：对东南极拉斯曼丘陵地区典型的暗色麻粒岩及其主要矿物组合、区域最常见的变质矿物石榴石的Sm-Nd同位素年代测定表明,本区主期低压麻粒岩相变质作用发生在早古生代早期(泛非事件)。暗色麻粒岩—紫苏辉石—角闪石—斜长石Sm-Nd等时年龄为540±75(2σ)Ma。片麻状浅色花岗岩—石榴石—钾长石Sm-Nd等时年龄为497±7(2σ)Ma。野外地质证据还表明,本区的构造面貌和变质记录主要是早古生代早期热事件形成的,并与这一时期部分熔融事件关系密切。Sm-Nd isotopic dates of both a representative mafic granulite sample (G212-3, M_1) and a gneissic leucogranite sample(W20401,M_1) indicate that the low-pressure granulite facies metamorphism in the Larsemann Hills, East Antarctica occurred in earlier Early Paleozoic ('Pan-African Event'). The former (G212-3), which consists of orthopyroxene-hornblende -plagioclase-whole rock yields an internal isochron of 540±75 (2σ) Ma; the latter (W20401), which is made up of garnet-K-feldspar-whole rock gives an internal isochron of 497±7 (2σ)Ma. Evidence from field geology shows that the low-pressure granulite facies metamorphism in the area was accompanied by extensive patial melting as well.

关 键 词：麻粒岩 岩相 变质事件 钐同位素 

分 类 号：P588.346[天文地球—岩石学]