The Uplift Process Research Of Post-Orogeny Action In Dabie Area

This preliminary research focus on the tectonic uplift in late Mesozoic-earlyCenozoic after the main collision oregeny to understand more and detail on the total process of tectonics evolvement in east Dabie Mountain and Beihuaiyuan area. The research works that have been done are: apatite fission track dating, apatite thermal-evolvement patterns; the fluid characteristics including fluid inclusions' microthermometer, the compositions, 5 D - 8 18O, and their geochemistry , thermodynamics parameters. And also analyzed apatite's U-Th/He ages to understand more about the last uplift. The research integrated the all information of apatite thermol-chronology, the thermodynamics parameters and compositions of fluid inclusions and discussed their tectonics implies. We get some improvements understanding in post collision orogeny in researched area which include:1) There were two main tectonic uplifts in the late of Mesozoic to early Cenozoic. One was in late Jurassic-early Cretaceous and another was in late Cretaceous-early Tertiary. The dome uplift and fault uplift with the heterogeneous evolution in time and space were main two uplift patterns. The uplift of post-orogency of this area was very slow and the amount of exhumation is about 3-4km since Cretaceous and it does not show sharp response for the uplifting of Tibet. It should imply the effect from the subduction and collision of Indian and Asian blocks was very limited in this area. During that the tectonic process in eastern and western of China were controlled by different dynamics mechanisms2) The researched area was controlled by stretch and extended during late Mesozoic-early Cenozoic;3) The Xiaotian-Mozitan fault acted just as a main fault in intro-continent. The uplift in Cenozoic was more effected by the stress adjusting in the crust.4) We tried and did some innovation work and got unproved results which include: dating fission track by a new method, modeling apatite T-t plot of below 120 , analyzing the impact of spontaneous track on dating and fluid inclusion's tectonic implies. And the comparing research on fluid inclusions shows the pressure correction is very important to get fluid inclusions' trapped temperature, pressure and 18O isotopic composition.