Abstract:
New 40Ar/39Ar ages of adularia from three epithermal vein deposits in the Hauraki Goldfield constrain when these deposits formed. Adularia from veins at Neavesville has 40Ar/39Ar plateau and isochron ages of 6.89 ﾱ 0.02 and 6.86 ﾱ 0.02 Ma, respectively, similar to the 40Ar/39Ar plateau and isochron ages of adularia from veins at Golden Cross of 6.96 ﾱ 0.04 and 6.93 ﾱ 0.03 Ma, respectively. In contrast, Komata mineralisation formed at 5.99 ﾱ 0.02 to 6.07 ﾱ 0.03 Ma, based on the 40Ar/39Ar isochron and plateau ages of the adularia in these veins, similar to the previously reported 6.0 Ma age of mineralisation at Waihi/Favona. These preliminary data suggest that mineralisation in the Hauraki Goldfields occurred episodically.
