Isotopic age spectrum of the Huangling granitic batholith,western Hubei

The Rb Sr isochron ages and zircon U Pb concordant ages for main rock suites of the Huangling granitic batholith have been recalculated with the Isoplot program (Ludwig,1994),and the intrusive ages have been measured of variant kinds of dikes in the batholith. A age spectrum of magmatic activity have been obtained: the emplacement ages of the Taipingxi tonalite,Huanglingmiao granodiorite and Dalaoling quartz adamellite suites are (833±29 )Ma,(819±7) Ma and (786±54) Ma,respectively;the emplacement ages of granodiorite porphyry,diabase and quartz veines are 813 Ma,770 Ma and 772 Ma,which shows the end of magmatism and elevation of the batholith. Whole rock e Nd ( t ) and e Sr ( t ) values of the Huangling granitoid batholith indicate a continuous magmatic evolution series except for the Dalaoling suites and the magma might be derived from the subduction occurred beneath northern Yangtze plate during Jinningian.