渤海盆地现今岩石圈热结构及新生代构造-热演化史

依据236口井共2 706组的静温数据以及25口井的系统测温数据，分析计算了渤海盆地地温梯度及大地热流；建立地壳分层结构模型，利用回剥法计算现今地幔热流、深部温度以及岩石圈厚度；在此基础上，利用地球动力学方法恢复本区热流演化史。结果表明：渤海盆地背景地温梯度为322 ℃/km，热流值为648 mW/m2；盆地现今热岩石圈厚度在61~69 km之间，地幔热流占地表热流的比例在60%左右，属于“热幔冷壳”型岩石圈热结构，盆地地壳底部或莫霍面温度变动在548~749 ℃之间；热流演化的特征与盆地的构造演化背景吻合，新生代以来盆地经历了3期岩石圈减薄并加热的过程，在东营组沉积末期热流达到最高(70~83 mW/m2），这期间盆地内产出多期碱性玄武岩，表明盆地经历了波及地幔的裂谷过程，随后进入热沉降期，热流逐渐降低，盆地向坳陷型转变。

Present day Geothermal Structure of Lithosphere and the Cenozoic Tectono thermal Evolution of Bohai Basin

Based on 2,706 static temperature measurements in 236 boreholes and system temperature measurements in 25 boreholes, the geothermal gradient and heat flow of Bohai basin were calculated. By setting up typical crustal structure models in this area, the mantle heat flow, deeper temperature and thermal lithosphere thickness were calculated by the “stripping” method. Based on the dynamic model of the Earth, the heat flow evolution in this area was reconstructed. The results show that the background geothermal gradient is 322 ℃/km, and the heat flow is 648 mW/m2. The present day lithosphere thickness ranges from 61 km to 69 km, and the ratio of mantle heat flow in the surface heat flow is about 60%, while the type of lithosphere geothermal structure is “hot mantle and cold crust”, and the temperature of the bottom of crust ranges from 548 ℃ to 749 ℃. The heat flow evolution coincides with the tectonic subsidence history. After three phases of heating and thinning of lithosphere, the heat flow reached the maximum (70-83 mW/m2） at the end of Dongying depositional duration. It is suggested that the basin has experienced the process of syn rift phase involving the mantle and combining with multiphase alkaline basalt in the basin. As the heat flows decreasing in thermal subsidence phase, the type of basin transforms into depression.