Late Cretaceous rapid exhumation of the Central Tibetan Plateau: Insights from low-temperature thermochronology

The uplift history of the Tibetan Plateau is a hot topic for the geological study. The Lhasa terrane, situated on the southern edge of Eurasian plate, records the tectonic evolution of the Tibetan Plateau preceding the collision between the Indian and Eurasian continental plates. This paper employs low-temperature thermochronological methods, including zircon and apatite (U-Th)/He dating, as well as apatite fission track (AFT) analysis, to investigate the Bange pluton in the northern Lhasa terrane. The research results indicate that the zircon and apatite helium (ZHe and AHe) ages from the plutons range from 90 to 78 Ma and 83 to 63 Ma, respectively, while the AFT ages span from 65 to 46 Ma. Thermal history reveals that the Bange pluton experienced a rapid cooling phase during the Late Cretaceous (from ~94 to 70 Ma), with a cooling rate of ~4.2 °C/Ma, subsequently followed by a slow cooling rate with ~1.1 °C/Ma. These results suggest that the Bange pluton has underwent rapid uplift during the Late Cretaceous to Paleocene. This Late Cretaceous rapid cooling event is also observed in other regions of the Lhasa terrane, indicating a widespread period of rapid cooling and exhumation. Since the Cenozoic, the cooling rate of the Bange pluton has significantly decreased, which would suggest that the tectonic uplift of the central Tibetan Plateau may not be related to the India-Asia continental collision. Considering the regional tectonic context, the collision between the Lhasa terrane and the Qiangtang terrane during the Late Jurassic to Early Cretaceous may have initiated the exhumation of the Lhasa terrane in the Late Cretaceous.