四川盆地北部热史波动模型的建立和应用

Establishment and application of the thermal wave model of the deposition in the northern Sichuan Basin

基于四川盆地北部沉积波动的特点,结合该区的实际地质特征,在该区初步建立了热史波动模型,并应用该模型结合镜质体反射率古温标对四川盆地的大地热流史演化进行恢复,同时利用磷灰石裂变径迹数据对模拟结果进行检验.模拟实验结果表明:志留纪至二叠纪大地热流值波动上升,波动幅度不大,热流值总体相对较低(50 mW/m2),此阶段热流值的波动主要是在海西构造运动作用下,地壳抬升或下降造成的;二叠纪至早侏罗世,是本区热流值最高阶段,最高可达56mW/m2,并且持续时间达到35 Ma,之后降低;此后大地热流值随时间波动上升.从热史波动曲线可以看出,这些波动主要是各期构造运动作用造成地层的抬升剥蚀而形成的.波动热史模型模拟的结果为该区成藏演化史研究奠定了基础.

A thermal wave model of this area is established based on the actual geological data in the northern Sichuan Basin by means of wave analysis.The thermal history of the studied well is stimulated based on the vitrinite reflectance data by using the thermal wave model,and the simulation result is verified by the apatite fission track data of the well.The simulation result shows that the heat flow wavelike rises from Silurian to Permian,but the magnitude of the heat flow and the amplitude of its wave are all less as a whole.The wave of the heat flow is resulted from the earth's crust rising and subsiding under the action of Hercynian movement.From Permian to the early Jurassic,the heat flow value in the studied area is higher,and the maximum of the heat flow value reaches to 56 mW/m^2.The higher heat flow value lasts 35 Ma,and then the heat flow value decreases.Afterwards the heat flow value wavelike rises with time.According to the curve of heat flow evolution,the waves of the heat flow are all resulted from the earth's crust rising and subsiding under the action of structural movements.The simulation result of thermal wave history supplies the basis for the study of the evolution of the reservoir in the studied area.