鄂尔多斯盆地延长组前积反射结构及地质意义

Progradational Reflection Structure of Yanchang Formation in Ordos Basin and Its Geological Significance

论文应用了鄂尔多斯盆地中生界延长组的测井、地震资料,从三角洲—深水沉积方面揭示鄂尔多斯盆地西南部地区延长组的前积反射地质含义。结果表明,前积结构顶部的平行反射或亚平行反射代表河流三角洲沉积环境,沿斜坡发育的高振幅前积反射代表三角洲前缘或前三角洲沉积环境,前积体底部连续高振幅的平行反射代表深水沉积环境发育,前积层中出现的高振幅凹凸点、大凹面反射验证存在砂体输送通道,前积体底部的弱振幅近平行反射是稀释浊流形成的细粒沉积物。综合认为,前积体只出现顶部平行反射和倾斜的前积反射时不发育深水沉积,深水扇环境多存在于有输送通道和底部高振幅平行反射的前积体中。

In order to know the specific geological meaning in the seismic profile,the logging and seismic data of Mesozoic Yanchang Formation in Ordos Basin are applied,The geological implication of progradational reflection of Yanchang Formation in the southwest of Ordos Basin is revealed from the aspect of delta deep-water sedimentation.The results show that the parallel reflection or sub parallel reflection at the top of the progradation structure represents the fluvial delta sedimentary environment,the high amplitude progradation reflection along the slope represents the delta front or prodelta sedimentary environment,and the continuous high amplitude parallel reflection at the bottom of the progradation body represents the deep-water sedimentary environment.The large concave reflection represents the existence of sand transport channel,and the weak amplitude near parallel reflection at the bottom of the progradation represents the fine sediment formed by diluted turbidity current.It is generally considered that deep-water deposition is not developed when only the top parallel reflection and inclined progradation reflection appear in the progradation,and the deep-water fan environment mostly exists in the progradation with transport channel and high amplitude parallel reflection at the bottom.