Combined apatite fission track （AFT） and （U-Th）/He （AHe） thermochronometries can be of great value for investigating the history of exhumation of orogenic belts. We evaluate the results of such a combined approa...Combined apatite fission track （AFT） and （U-Th）/He （AHe） thermochronometries can be of great value for investigating the history of exhumation of orogenic belts. We evaluate the results of such a combined approach through the study on rock sam- ples collected from the Baluntai section in the Tianshan Mountains, northwestern China. Our results show that AFT ages range from -60 to 40 Ma and Atte ages span -40-10 Ma. Based on the strict thermochronological constraints imposed by AHe ages, forward modeling of data derived from AFT analyses provides a well-constrained Cenozoic thermal history. The modeled re- sults reveal a history of relatively slow exhumation during the early Cenozoic times followed by a significantly accelerated exhumation process since the early Miocene with the rate increasing from 〈30 m/Myr to 〉 100 m/Myr, which is consistent with the inference from the exhumation rates calculated based on both AFT and AHe age data by age-closure temperature and mine- ral pair methods. Further accelerated exhumation since the late Miocene is recorded by an AHe age （-11 Ma） from the bottom of the Baluntai section. Together with the previous low-temperature thermochronological data from the other parts of the Tianshan Mountains, the rapid exhumation since the early Miocene is regarded as an important exhumation process likely pre- vailing within the whole range.展开更多
基金supported by National Natural Science Foundation of China(Grant No.41001002)China Postdoctoral Science Special Foundation(Grant No.201003277)
文摘Combined apatite fission track （AFT） and （U-Th）/He （AHe） thermochronometries can be of great value for investigating the history of exhumation of orogenic belts. We evaluate the results of such a combined approach through the study on rock sam- ples collected from the Baluntai section in the Tianshan Mountains, northwestern China. Our results show that AFT ages range from -60 to 40 Ma and Atte ages span -40-10 Ma. Based on the strict thermochronological constraints imposed by AHe ages, forward modeling of data derived from AFT analyses provides a well-constrained Cenozoic thermal history. The modeled re- sults reveal a history of relatively slow exhumation during the early Cenozoic times followed by a significantly accelerated exhumation process since the early Miocene with the rate increasing from 〈30 m/Myr to 〉 100 m/Myr, which is consistent with the inference from the exhumation rates calculated based on both AFT and AHe age data by age-closure temperature and mine- ral pair methods. Further accelerated exhumation since the late Miocene is recorded by an AHe age （-11 Ma） from the bottom of the Baluntai section. Together with the previous low-temperature thermochronological data from the other parts of the Tianshan Mountains, the rapid exhumation since the early Miocene is regarded as an important exhumation process likely pre- vailing within the whole range.
