东南极普里兹湾Sφstrene岛麻粒岩变质年代及其与邻区的关系

AGE OF THE METAMORPHIC EVENT OF THE GARNET PYROXENE GRANULITE FROM THE SOSTRENE ISLAND,PRYDZ BAY,EAST ANTARCTICA AND ITS RELATION TO THE NEIGHBOURING AREA

对东南极普里兹湾Ｓｓｔｒｅｎｅ岛石榴辉石麻粒岩的变质年龄通过Ｓｍ－Ｎｄ法做了重新测定，得出６０４±２８（２σ）Ｍａ的石榴石－辉石－斜长石－全岩矿物内部等时线年龄，并指出本数值代表了该区主期中压麻粒岩相变质年龄。至于与其北东部的Ｂｏｌｉｎｇｅｎ群岛、拉斯曼丘陵的关系，通过岩石组合，变质叠加及其空间变化特征并结合变质时代推断，自Ｓｓｔｒｅｎｅ岛至拉斯曼丘陵后期低压变质叠加逐渐增强。

Redetermination of the metamorphic age of the garnet bearing mafic granulite from the Sφstrene Island,Prydz Bay,East Antarctica,has been made and an isochron of whole rock garnet pyroxene plagioclase is obtained,giving an age of 604±28(2σ)Ma. It is pointed out that this age represents the time of peak granulite facies metamorphism of the area.As to the geological relation of the Sφstrene Island with the Bolingen Islands and Larsemann Hills to the northeast,it is deduced from the rock assemblages,metamorphic superposition and spatial changes and metamorphic age features between the above regions that the degree of the superposition of the late low pressure metamorphism is becoming stronger from west to east.While the evolution of the earlier medium pressure to late low pressure implies probably the substages of the same metamorphic cycle.