Abstract: Sichuan Basin, one of the important oil-gas-bearing basins in China,is well known for its low geothermal gradient only from 2.0 to 2.5℃/100m.According to the present study on the paleogeotemperature by various methods,it has been found that the paleogeothermal gradient in the basin was as high as 3.2 to 4.8℃/100m in the period of terminal Early Cretaceous to Eocene.The highest paleogeotemperature was in the bottom of Upper Triassic from 160 to 280℃.The high paleogeotemperature is considered to have an important influence on the production of natural gas as well as on the compaction of reservoir with ultralow porosity and permeability.

Key words: Sichuan Basin, paleogeotemperature, vitrinite reflectance, fission track

摘要： 四川盆地是我国重要的含油气盆地之一,素以“冷盆”着称,地温梯度(2.0～2.5)℃/100m.但近年来通过镜质体反射率法、矿物包裹体测温法、粘土矿物相转变法以及裂变径迹法等多种手段进行古地温研究之后发现,四川盆地早白垩世末至始新世期间古地温梯度曾高达(3.2～4.8)℃/100m,上三叠统底部最高古地温曾高达160～280℃。高古地温对于四川盆地天然气的生成和超低孔渗储层的致密化作用均有重要影响。

关键词: 四川盆地, 古地温, 镜质体反射率, 裂变径迹