Abstract: The Yangshan gold ore belt has become an ideal place for studying geochronology of mineral deposits because of its unique tectonic location, ultra-large gold resources, large-scale uplifting and post-mineralization erosion events. Based on the previous studies, we carried out zircon and apatite fission track analysis on the thermochronology of the Yangshan gold ore belt. The results show that the distribution range of zircon fission track age was from 287.0±21 to 101±3 Ma (1σ), with the following characteristics based on lithology: (1) The zircon fission track ages of sandstone and slate had the largest age span, ranging from 287 to 107 Ma; (2) The distribution range of phyllite zircon fission track was between 177 and 101 Ma; and (3) plagio granite porphyry zircon fission track age ranged from 193 to 185 Ma. The apatite fission track age ranged from 69±7 to 46±14 Ma (1σ), and fission track length and its distribution characteristics show that the Yangshan gold ore belt moved monotonously and slowly through the closure temperature of apatite fission track, between the Late Cretaceous to Paleocene. Based on the thermal history analysis of apatite fission track lengths and age inversion, combined with paleogeothermal gradient and ore body metallogenic depth in the study area, we concluded that the Nishan ore body was denuded before the Getiaowan ore body section. From the Cretaceous Period, in the Yangshan gold ore belt, the total thickness of the eroded stratum was about 12.24 km, and the upper limit on the eroded ore body thickness was about 880 m. We speculated that the less eroded ore-zone in the northern Yangshan gold belt may have large prospecting potentials.

Key words: fission track, thermochronology, Yangshan gold ore belt, West Qinling