40 AR/ 39 AR ISOCHRON AGE OF THE XIWAN ALBITE GRANITE IN DEXING,JIANGXI,DETERMINED BY THE LASER MASS SPECTROMETRY

Ar/Ar 39 isochron dating of the Xiwan albite granite in Dexing,Jiangxi,yielded an isochron age of （927 9±18 6） Ma This age is the crystalization age of the albite granite acomponent of the bleached intrusion in the Northeast Jiangxi ophiolite suite when it was cooled to 350℃ The age should be the upper limit of the formation age of the ophiolite suite Through consulting the recently published Sm Nd,U Pb and 40 Ar/ 39 Ar ages of related rocks,the formation and tectonic emplacement ages of this ophiolite suite are discussed in this paper