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Ar- 39Ar fast neutron activation age spectrum of quartz in ore collected from the Baiyangping Cu-Co polymetallic ore-concentrated area, Lanping Basin, is saddle-shaped. The plateau age, minimum appearance age and isochron age shown on the spectra are 56.53± 0.43 Ma, 55.52± 1.78 Ma and 55.90± 0.29 Ma respectively. The age data are consistent with each other within 1σ uncertainties. Because the given initial 40Ar/ 36Ar value of 294.7± 1.14 is very close to Nier’s value ( 295.5±5), both plateau and isochron ages may be considered as the forming time of quartz. So the age of 55.90- 56.53 Ma represents the forming age of ore deposits. It is obvious that the ore deposits were formed during the Early Himalayan period.
Ar-39Ar fast neutron activation age spectrum of quartz in ore collected from the Baiyangping Cu-Co polymetallic ore-concentrated area, Lanping Basin, is saddle-shaped. The plateau age, minimum appearance age and isochron age shown on the spectra are 56.53 ± 0.43 Ma, 55.52 ± 1.78 Ma and 55.90 ± 0.29 Ma respectively. The age data are consistent with each other within 1σ uncertainties. Because the given initial 40Ar / 36Ar value of 294.7 ± 1.14 is very close to Nier’s value (295.5 ± 5), both plateau and isochron ages may be considered as the forming age of ore. It is obvious that the ore deposits were formed during the Early Himalayan period.