岩石圈流变性对拉张盆地构造热演化历史的影响

采用粘弹性动力学模型模拟研究了岩石圈流变性对拉张盆地构造热演化的影响. 模拟研究发现,盆地的构造热演化特征与盆、缘岩石圈强度对比相关,盆地岩石圈强度相对外缘岩石圈强度越弱,盆地沉降量越大,且在拉张结束与热沉降之间出现较大的基底抬升、热流持续高值;无论是初始岩石圈力学厚度、泊松比,还是下伏流体软流圈的负密度差,都是影响盆地构造热演化历史的因素;同时,拉张前断层的存在也是影响盆地基底形态的重要因素,其存在不仅会产生较大的基底落差,还会加深盆地中心的沉降.

EFFECTS OF LITHOSPHERIC RHEOLOGY ON THERMAL- MECHANICAL MODELING OF EXTENSIONAL BASINS

A dynamic model,visco-elastic model,is used to study the effects of lithospheric rheology on the thermal-mechanical modeling of extensional basins. It is found that the strength contrast of the basin lithosphere to the stable lithosphere outside the basin influences strongly the thermal-mechanical history of the basin. The weaker the strength of the basin lithosphere,the deeper basin subsides and the higher the heat flow peak is. Besides,there is a transition stage after the extension stops,when the basin uplifts and heat flow maintains high value. Model results show that the initial thickness of the mechanical lithosphere,the Poisson's ration of the lithosphere,and the assumed lower density of the asthenosphere are also the factors influencing the model results. Preexisting faults are another factor that influences the basin evolution and basement structure. If the preexisting faults are added into the model,a big fall may be produced,that will make the basin center deeper.