论文部分内容阅读
It is still controversial how the high elevation of the Tibetan Plateau established after theIndian-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 mod river sand in the west 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 experi-enced 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 aver-age 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 south margin of the Gangdese magmatic arc attained high elevation after the Oligocene.