ISOTOPIC AGE DETERMINATION ON MIGMATITE IN SHAOXING-JIANGSHAN RIFT ZONE AND ITS METAMORPHIC ROCK AT BOTH SIDE-BASEMENTS

Ⅰ. INTRODUCTION Shaoxing-Jiangshan rift zone is on the boundary of geotectonic units of first order in Zhejiang Province (Fig. 1). The basement complex of 'epicontinental basin', called as Shuangxiwu Group, is composed mainly of the metamorphic rock series on its north side within Zhejiang, and can be correlated to Presinian system in