川东北地区异常高压形成的地温场背景

利用四川东北地区现有的钻井测温数据及测定的岩石样品热导率数据，计算了12口钻井的大地热流值. 结果表明，川东北地区现今地温梯度为18～25 ℃/km，平均21 ℃/km，大地热流值介于41～57 mW/m2之间，平均为49 mW/m2. 在此基础上，利用镜质体反射率(Ro)资料对研究区热史进行了恢复，认为研究区在255Ma左右古热流达到最高值(62～70 mW/m2)，此后热流持续降低直到现今；研究区中-新生界不整合面的剥蚀厚度最大，可达约2100 m；异常高压是在低热流的地温场背景下形成的.

The background of the geothermal field for formation of abnormal high pressure in the northeastern Sichuan basin

Based on available borehole temperature logging and thermal conductivity measurement of core samples in the northeastern Sichuan Basin, we have estimated 12 terrestrial heat flow values. The results show that the present_day geothermal gradients ranges from 18 to 25℃/km, with an average of 21℃/km, and that the present_day heat flow varies from 41 to 57 mW/m2, with a mean of 49 mW/m2. Thermal history reconstruction in the northeastern Sichuan basin using vitrinite reflectance data indicates that the paleo_heat flow reached the maximum values (62～70mW/m2) around 255Ma, and then decreased till present. The maximum erosion occurred on the Mesozoic_Cenozoic unconformity and reached ～2100 m. The abnormal high pressure in the area was formed under geotemperature background characterized by low paleo_heat flow.