宁武-静乐含煤盆地构造-热演化史恢复

宁武-静乐盆地是华北地区重要的含煤构造盆地，是山西省煤层气勘探主要区域。本文基于镜质组反射率及磷灰石裂变径迹古温标，恢复了盆地的构造-热演化史。研究结果表明，石炭系太原组煤层的Ro值主要反映中生代晚期地层达到最大埋深时的古地温状况，根据最大古埋藏深度，获得盆地的古地温梯度约3.88 ℃/100 m～4.34 ℃/100 m。裂变径迹资料抬升冷却分析，得出盆地经历了70～63 Ma和38～20 Ma以来的两次快速抬升。构造-热演化史研究表明，盆地经历的最大古地温时期是在晚侏罗世-早白垩世达到的，该时期是煤层气主要生成期。晚白垩世期盆地抬升冷却，地温明显降低，生气作用减弱及停止。镜质组反射率和裂变径迹所揭示的热演化史对于深化认识宁武-静乐盆地的煤层气勘探开发具重要意义。

Tectonic-thermal history reconstruction of Ningwu-Jingle coal-bearing basin

Ningwu-Jingle Basin is one of the important coal-bearing basins in North China. It is major area of CBM exploration in Shanxi Province. This work studies the thermal evolution history of this area based on vitrinite reflectance and apatite fission track analysis，and reconstructs the tectonic-thermal history of basin. Vitrinite reflectance shows Carboniferous Taiyuan Formation’s paleotemperature conditions when the Late Mesozoic formations at maximum burial depth. According to maximum burial depth，the paleo-geothermal gradient was higher than the current，which was about 3.88 ℃/100 m～4.34 ℃/100 m. Fission track analysis，the basin has experienced twice rapid uplift in 70～63 Ma and 38～20 Ma. The thermal evolution history study results show that the basin experienced maximum paleotemperature in Late Jurassic to the Early Cretaceous which occurred a tectonic-thermal event. It is important gas-generation period of  coalbed methane. Basin uplift in Cenozoic era，and ground temperature decrease，gas-generation is decreased and stopped. This modeling result suggests evolution in the Ningwu-Jingle Basin，which has some significance to exploration of coal bed gas in this region.