Abstract:

The geothermal history of strata or rocks has been qualitatively and semi-quantitatively in Shiwanshan basin and its neighbouring region, based on analyses of fission-track apparent age and modelling of confined track lengths distribution of apatite samples.The results show that all samples have experienced paleogeotemperatures of over 60～70℃;the basement strata(T₁b) on the northwestern side of Shiwanshan basin have been uplifted and denuded to the near-surface (with a paleogeotemperature of below 70℃) much more earlier than the basement rocks(γ₅¹)on the southeastern side of the basin and the paleogeothermal history of samples from the basin can be divided into six stages,they are the fast burial and increasing temperature(T₃-J₃)stage,transient decreasing temperature(latest J₃-early K₁)stage,burial and increasing temperature(K)stage,rapid decreasing temperature(last K₂-E₁)stage,relatively stable (E₂-E₃)stage and another rapid decreasing temperature (since N₁)stage.

Key words: Shiwanshan basin, apatite fission tracks, forward modelling of confined track-length distributions, geothermal history