Exhumation history of the Micangshan-Hannan Dome since Cretaceous and its tectonic significance: evidences from Apatite Fission Track analysis

Apatite Fission Track (AFT) data of the Micangshan-Hannan Dome region is reported in this work. It is shown that AFT ages decrease gradually from the inner part of the Micangshan-Hannan Dome to North Sichuan Basin, which is consistent with the piggyback propagation model of thrusting in the region proposed by previous works based on seismic survey profiles. Thermal history modeling of the AFT data shows that the Micangshan-Hannan Dome experienced two episodes of rapid cooling occurred in Cretaceous (before similar to 90Ma) and Late Cenozoic (since about 15Ma) respectively. The Cretaceous rapid cooling of this region is coeval with the regional cooling event in Qinling-Dabie Orogen, which is possibly resulted from the far-field effects of tectonic events in the nearby regions (eg. Siberia-Mongolia-Sino-Korean and Lhasa-West Burma-Qiangtang-Indochina collisions, Pacific subduction and Pacific back-arc extension since Early Cretaceous). The Late Cenozoic rapid cooling since similar to 15Ma is attributed to the northeastward growth of the Tibetan Plateau.