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

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.