Fission track evidence on thermal history of Jiama polymetallic ore district,Tibet

It is a new attempt to study thermal evolution related to mineralization using the fission track (FT) method. Apatite and zircon fission track data are reported for 6 samples collected from Jiama ore district as well as its periphery. The FT ages of apatites in the ore district are (16.1±0.9) Ma and (18.8±1.1) Ma and reflect the age of late period of hydrothermal mineralizing event. Apatite FT age of (22.0±4.3) Ma and zircon FT age of (20.9±2.0) Ma are related to the early period of mineralization. Another zircon FT age of (341.6±79.1) Ma, inheriting mineral source characteristic, has no connection with the mineralization. Based on the thermal history analysis, the mineralization began before 25–22 Ma. Cooling rate in the ore district is 5–6°C/Ma averagely, in which a slow cooling occurred at 90–80°C. About 2.7 km has been denuded and the denudation rate is higher than the uplifting rate.