| A thermal history was modeled by fission track dating in Jinsha area of Guizhou Province. Combined with geologic analysis, the subsidence, uplift and denudation processes of the Qianzhong Uplift are restored. This uplift has experienced 2 stages of processes: a) subsidence, burial and temperature rise from 180Ma to70 Ma; b) denudation and temperature decrease from 70 Ma till now. During the subsidence stage, the rate of temperature increase was 0.909℃/Ma and the corresponding sedimentary thickness of T3-K was about 4550m. during the denudation and temperature decrease, the curves of temperature decrease show three parts: a) from 70 to 15 Ma,sample temperature decreases from 120 to 60 ℃by the rate of 1.09 ℃/Ma; b) from 15 to 5 Ma, it has a smooth stage and sample temperature keeps at 60 ℃; c) from 5 Ma till now, sample temperature decreases quickly from 60 to 20 ℃by 8℃/Ma, which corresponds to Himalayan uplifts of the Yunnan and Guizhou Plateau. Calculation shows that the thickness of uplift and denudation has been about 2800m since Late Cretaceous period. |
