Preservation of Xiuwacu W-Mo deposit and its constraint on the uplifting history of Eastern Tibetan Plateau

Thermochronology has become an increasingly effective tool to reveal the post-mineralization uplift and exhumation history of ore deposits. In this paper, we studied the exhumation history and preservation conditions of the Xiuwacu tungsten-molybdenite deposit (resource: 24,000 t Mo and 23,000 t WO3), which is located on the southern Yidun Terrane (SYT), Eastern Tibetan Plateau. At Xiuwacu, both the eastern and western ore zones contain quartz-vein-type orebodies in the K-feldspar, greisen, and silicic alteration zones. The orebodies distributed in a northwestward trend along regional faults, with ore minerals including mainly molybdenite, scheelite, chalcopyrite, and pyrite. The mineralization at Xiuwacu occurred in 86-82 Ma, coeval with the emplacement of the ore-causative Xiuwacu porphyry monzogranite. The deposit likely underwent rapid cooling from 750 800 degrees C (magmatic zircon U-Pb age) to similar to 300 degrees C during 90-86 Ma (molybdenite Re-Os mineralization age). After that, the temperature slowly and continuously cooled to similar to 180 degrees C from the Late Cretaceous to 25 Ma, and then rapidly cooled to similar to 125 degrees C in 25-17 Ma, and eventually to 125-60 degrees C during 17-5 Ma (apatite fission-track ages; n = 8). The thermochronologic history of the Xiuwacu intrusive complex was reconstructed by inverse modelling based on the apatite fission-track ages and lengths. There was 6426-6915 m (average 6650 m) uplift, while only 1982-2471 m (average 2200 m) exhumation. Considering the depth of current exploration and typical depth of granitoid-related W-Mo mineralization, we infer that there is still great potential to discover concealed W-Mo orebodies beneath the current mining level at Xiuwacu.

Automated summary

Thermochronology is an effective tool to study the uplift and exhumation history of ore deposits. This study focused on the Xiuwacu tungsten-molybdenite deposit in the Yidun Terrane, Eastern Tibetan Plateau, revealing a history of rapid cooling and subsequent gradual cooling of the deposit over millions of years. The study suggests there may be potential for discovering concealed orebodies at depth beneath the current mining level at Xiuwacu.