渤海湾盆地临清坳陷的数值模拟与异常沉降

Numerical Simulation and Abnormal Sedimentation of Linqing Depression on Bohai Bay Basin

为探索渤海湾盆地南部的临清坳陷机理,本文利用回剥法和改进的有限元应变速率反演技术,基于3个剖面14口实际井和合成井的数据,获取了拉伸因子、应变速率、计算沉降量等数据,揭示了基于观测沉降量和计算沉降量井差值的异常沉降现象:中新世时期负差值的减速沉降,和上新世至第四纪时期正差值的加速沉降。平衡剖面恢复和区域热流值计算则指示了中新世减速沉降的机制主要为热源的持续流入,抑制了岩石圈的热收缩;中新世以来的加速沉降则与后裂谷期的正断层活动密切相关。

In order to explore the mechanism of the Linqing depression in the southern Bohai Bay Basin,this paper uses the back-stripping method and the improved finite element strain rate inversion technique.Based on the data of 14 actual and synthetic Wells in 3 profiles,the data of tensile factor,strain rate and calculated settlement are obtained,and the abnormal settlement phenomenon based on the well difference between observed settlement and calculated settlement is revealed:The deceleration of negative difference in Miocene period,and the acceleration of positive difference in Pliocene to Quaternary period.The restoration of the equilibrium profile and the calculation of regional heat flow indicate that the mechanism of the slow subsidence in Miocene is mainly the continuous inflow of heat source,which inhibits the thermal contraction of the lithosphere.The accelerated subsidence since Miocene is closely related to the normal fault activity in the post-rift period.