赣中相山新元古代变质岩的首次确定

FIRST DETERMINATION OF THE NEOPROTEROZOIC METAMORPHIC ROCKS IN XIANGSHAN, CENTRAL JIANGXI PROVINCE

相山地区变质岩划分为４个变质岩带，由南往北依次分布，构成典型的递增变质带。十字石的出现表明变质作用已达到低角闪岩相。获得十字石云母片岩及斜长角闪片岩ＲｂＳｒ等时年龄分别为７１９．７、７２７．６Ｍａ。首次厘定相山变质岩形成于新元古代，而非加里东期变质。

In this paper metamorphic rocks in the Xiangshan area fall into four metamorphic belts, i.e.: the sericite chlorite phyllite belt, biotite schist belt, almandine mica schist belt and staurolite schist belt. Distributed successively from south to north, they form a typical zone of progressive metamorphism. The appearance of staurolite indicates that the metamorphism has reached the low amphibolite grade. The staurolite mica schist and plagioclase amphibole schist have been determined to have Rb Sr isochron ages of 717.7 and 727.6 Ma, respectively. It is first ascertained that the metamorphic rocks were formed in the Neoproterozoic rather than in the Caledonian stage. The age of formation of their protoliths should be pre Sinian.