南黄海北部盆地中、新生代构造热演化史模拟研究

摘要

The tectono-thermal evolution history is dominated and influenced by deep geodynamic processes.Geodynamic modeling and traditional geothermometer simulation are integrated and applied to reconstruct the tectono-thermal evolution history of the Northern South Yellow Sea Basin during Mesozoic-Cenozoic.The simulation theory,methods,and work flow,which are based on the advanced McKenzie model,are introduced in this paper.The matching method of theoretical and calculated tectonic subsidence,definition of geophysical parameters,calculation of stretching factors and application of simulation results are also discussed.Modeling results indicate that the paleo-heat flow increased since Mesozoic,which is accompanied by intense rifting processes.The paleo-heat flow was likely to reach a maximum value of 80 mW · m-2 and the paleo-geothermal gradient could go up to 49 ℃/km during late Cretaceous to Palaeocene.Tectonic subsidence modeling results of single well show the characteristics of multi-stage rifting processes.The paleo-heat flow continuously decreased once the basin evolution turned into the post-rifting stage,and it reduced down to 65 mW · m-2 at the end of Miocene,which was accordant with present heat flow.The obtained geophysical parameters and modeling results of one-dimensional simulation have been applied in the reconstruction of three-dimensional paleo-geothermal field.The research methods and results are significant for the future study of tectonic evolution,resources evaluation and the petroleum system of the South Yellow Sea Basin.%盆地深部地球动力学过程控制和影响着浅部的构造热演化过程,针对南黄海北部中、新生界断陷盆地,将地球动力学模拟技术与传统古温标法相结合,对研究区中、新生代伸展断陷期演化以来的构造热演化史进行了研究.对基于改进McKenzie模型的数值模拟的原理、方法和过程进行了探讨,包括理论与计算构造沉降趋势拟合、伸展系数计算与误差校正、模拟参数定义及一维模拟结果的三维初步应用等方面.研究表明,南黄海北部盆地中生代以来伴随裂陷拉张过程其古热流整体呈现升高趋势,至晚白垩世末到古新世期间最高可达80 mW·m-2,古地温梯度最高可达49℃/km,部分单井构造沉降史模拟结果显示多期拉张特征,裂后期热流持续降低,至渐新世末到中新世热流约为65 mW·m-2,与现今热流值相当.利用一维数值模拟获取的相应参数及热史恢复结果,对盆地的古地温场进行了三维模拟恢复,取得了较好的应用效果,研究方法和成果对于盆地构造演化、油气资源评价及成藏模拟等均有重要意义.