Detrital Zircon Fission-Track Thermochronology of the Present-Day River Drainage System in the Mt. Kailas Area, Western Tibet: Implications for Multiple Cooling Stages of the Gangdese Magmatic Arc

Abstract

It is still controversial how the high elevation of the Tibetan Plateau established after the Indian-Asian collision during the Cenozoic. The timing of Gangdese magmatic arc exhumation and uplift history would provide useful message for this disputation. We present six zircon fission-track (ZFT) data from modern river sand in the western Tibet, around the Mt. Kailas, to decipher the long-term exhumation histories of the Gangdese magmatic arc. The data suggests that all the Gangdese magmatic arc rocks experienced rapid cooling during the Eocene (∼46’35 Ma) and Oligocene (∼31’26 Ma). The movement along the north-south trending extensional fault and dextral strike-slip Karakoram fault induced the adjacent rocks exhumed at the Middle Miocene (∼15’16 Ma) and Late Miocene (∼10’11 Ma), respectively. According to the minimum and central AFT ages for each sample, the fastest exhumation rate is about 0.4 km/Ma, with average long-term exhumation rates on the order of ∼0.3 km/Ma since the Oligocene. This result supports the outward growth model for plateau forming, indicating the southern margin of the Gangdese magmatic arc attained high elevation after the Oligocene.