渤海湾盆地剥蚀量恢复中的综合分析法

利用地震层速度法、镜质体反射率法、声波时差法、地质外推法等 ,确定渤海湾盆地中生界的剥蚀量 ,并建立起初步的埋藏史曲线 ,然后应用磷灰石裂变径迹长度分析技术 ,选定澳大利亚扇形模型 ,沿可能性最大的几种不同地质概念热史路径 ,对渤海湾盆地临清坳陷西部Q 5井等的白垩统地层的磷灰石裂变径迹长度分布进行了数值模拟 .通过与实测磷灰石裂变径迹长度分布的比较 ,确定了该井合理的、精确的地质演化历史 .模拟研究结果表明 ,Q 5井在距今 70Ma时 ,白垩系地层达到其演化历史上的最大埋深 (35 0 0m) ;之后发生构造抬升并遭受剥蚀 ,下白垩系地层的最大剥蚀量为 95 0m ,上白垩系地层的最大剥蚀量为 15 70m .研究过程证明 ,多种方法结合 ,比单纯用磷灰石裂变径迹热史分析法得出的结论可靠 .

Application of Synthetical Analysis Method for Seeking Eroded Strata Thickness of Mesozoic in Bohai Bay Basin

There are many ways in seeking the eroded strata thickness by the method of apatite fission track length distribution.In this article,the seismic strata velocity method, R 0 method,sound wave time difference method and geologic extrapolation are used firstly to get the eroded strata thickness of Mesozoic in Bohai Bay basin,and the cursory geologic bury history curve was established.After that,the technique of apatite fission-track length was applied and Australia fanlike model was selected.Through three different most possible paths of thermal history of geologic concept,we simulated apatite fission-track length distribution of lower Cretaceous strata of well Q-5 in Jinan district.Through comparing with the obtained fission-track length distribution,reasonable geological evolvement history is confirmed.Simulation results show that Cretaceous strata reach the most embedding depth(3 500 m) in 70Ma for well Q-5.Then,strata of well Q-5 underwent tectonic rise and denudation and maximum eroded thickness of Cretaceous strata is 1 570 m.It is certificated from the study process,the result got from many methods is much more acurate than the result got from the only apatite fission-track length distribution method.