Uplift and exhumation history of western Dangreyongcuo, Tibet: implications for preservation of the Xinlong gold deposit

Abstract

The western Dangreyongcuo area, located in the central-northern part of the Central Lhasa terrane, has witnessed a significant breakthrough in lode gold exploration through the recent discovery of the Xinlong gold deposit within continental volcanic sequences. As a key sector for investigating the tectono-thermal evolution of the Central Lhasa terrane, its post-Mesozoic cooling-exhumation processes provide critical constraints on deciphering the Tibetan Plateau uplift dynamics and associated resource-environmental feedbacks. However, this region has received limited systematic investigation to date. This study conducts zircon and apatite (U-Th)/He dating, along with apatite fission track dating, on granites from the Wenbu batholith in western Dangreyongcuo. Integrating these results with the tectonic-thermal evolution of the Lhasa terrane, we reveal the uplift and exhumation history of western Dangreyongcuo since the Mesozoic. Thermochronological data from five samples collected across the eastern and western sectors of the Wenbu batholith yield weighted mean zircon (U-Th)/He ages between 92.7 ± 3.6 Ma and 62.7 ± 2.5 Ma, weighted mean apatite (U-Th)/He ages between 53.9 ± 3.1 Ma and 32.8 ± 1.1 Ma, and central apatite fission track ages between 63 ± 3 Ma and 56 ± 3 Ma. HeFTy modeling reveals three cooling-exhumation phases in the western Dangreyongcuo region since the Late Cretaceous: Ⅰ) Rapid cooling stage (95–60 Ma): Cooling and exhumation rates were ∼2.9 °C/Myr and ∼95.2 m/Myr, respectively, associated with Lhasa-Qiangtang terrane collision and Neo-Tethyan Ocean northward subduction. Ⅱ) Slow cooling stage (60–35 Ma): Cooling and exhumation rates decreased to ∼0.8 °C/Myr and ∼26.7 m/Myr, linked to prolonged low-elevation, slow-uplift conditions in the Central Valley. Ⅲ) Renewed rapid cooling stage (35 Ma-present): Cooling and exhumation rates increased to ∼1.4 °C/Myr and ∼47.6 m/Myr, related to Lhasa lithospheric delamination and post-∼15 Ma Miocene activity of the Dangreyongcuo Rift, both driven by ongoing India-Eurasia collision. The integration of findings from this study with low-temperature thermochronological data from the Lhasa terrane collectively demonstrates differential evolution between the eastern and central sectors within the Central Lhasa terrane, while the entire Tibetan Plateau interior has undergone significant differential uplift since the Mesozoic. The preservation of the Xinlong high-sulfidation epithermal gold deposit despite intense uplift-denudation primarily resulted from protective burial by post-mineralization Zenong Group volcanic cover and fault-induced thickening of overlying strata caused by normal fault displacement. Prolonged low-elevation conditions and slow uplift rates within the Central Valley during the Eocene enhanced the preservation potential of the orebody.