济阳坳陷惠民凹陷热演化史分析

根据镜质体反射率数据和磷灰石裂变径迹数据对济阳坳陷惠民凹陷进行热演化模拟，分析了该区新生代的热演化状况。研究表明，惠民凹陷在地质演化过程中古地温是逐渐降低的，孔店组沉积末期到沙河街沉积末期地温梯度下降较快，孔店组沉积末期为4.4 ℃/100m左右，而到沙河街组沉积末期则降为3.7 ℃/100m左右，此后其地温梯度缓慢降低至现今的3.2 ℃/100m左右。同时，惠民凹陷内部构造的热演化亦存在一定差异，位于凹陷中部靠近临商断裂带的盘深3井的古地温梯度最高，其次为临82井；而位于凹陷东北部阳信洼陷的阳8井的古地温梯度最低。惠民凹陷的这种古地温演化特征是由该凹陷的构造运动演变决定的，并且和该凹陷新生代的断裂活动密切相关。

AN ANALYSIS OF THERMAL EVOLUTION HISTORY OF HUIMIN SAG IN JIYANG DEPRESSION

Thermal evolution of Huimin sag in Jiyang Depression is simulated by using the vitrinite reflectance (Ro) and apatite fission track data. The geothermal gradient in Huimin sag decreased gradually in the geologic evolutionary process. It declined rapidly from about 4.4℃/100m at the end of Kongdian stage to about 3.7℃/100m at the end of Shahejie stage, and has declined slowly to about 3.2℃/100m at present ever since. Moreover, the thermal evolutions of the structures within Huimin sag also vary to some extent, with the highest paleogeothermal gradient occurring in Well Panshen 3 in the central part of the sag and adjacent to the Linshang fault zone, followed by Well Lin 82, while the lowest paleogeothermal gradient occurring in Well Yang 8 in Xinyang area in the northeastern part of the sag. The paleogeothermal evolution of Huimin sag was controlled by its tectonic evolution and was closely related with the Cenozoic faulting in this sag.