东濮凹陷沙河街期盐湖盆地充填演化模式

东濮凹陷在古近系沙河街组沉积时期为1个盐湖盆地,自下而上发育了4套厚层盐岩,盐湖成因历来争议颇大。笔者在研究东濮凹陷沉积背景及沉积旋回的基础上,对东濮凹陷火山岩、盐岩及碎屑岩地层的垂向及平面组合特征进行了深入研究,认为东濮凹陷盐湖发育阶段与构造演化关系十分密切,盐湖发育期与凹陷强烈断陷期吻合。因此,结合该区的构造演化史、沉积充填史、火山活动史,综合分析了盐岩发育旋回的特征。东濮凹陷盐岩可划分为2大旋回,每一旋回又可分为初始裂陷期、强裂陷咸化高水位期、过补偿萎缩期3个阶段,据此建立了东濮凹陷拉张性盐湖盆地充填演化模式。该模式的建立,丰富了东部拉张型咸化湖盆充填演化理论。

Filling and evolution pattern of salt-lake basin at Shahejie Formation depositional stage in Dongpu Depression

Dongpu Depression is a salt-lake basin at Paleogene Shahejie Formation depositional stage,in which develops four sets of thick salt beds from bottom to top.The cause of formation for salt lake has always been controversial.On the base of study the sedimentary background and sedimentary cycle of Dongpu Depression,the author deeply analyzes the vertical and plane combination characteristics of volcanics,salt rocks and clastic rocks reservoirs.The view is that the salt-lake development stage and tectonic evolution in Dongpu Depression have very close relationships and the salt-lake development period coincides with the sag faulted period.Therefore,this paper comprehensively analyzes the characteristics of salt rocks development cycle combined with the histories of structural evolution,sedimentary filling and volcanic activity.The salt rock formation can be divided into two major cycles in Dongpu Depression.The single cycle evolution process can be divided into three phases which including initial chasmic stage,highly chasmic stage of high salt water period and over compensation basin atrophy phase.A filling and evolution pattern of extensional salt-lake basin is established.This model makes the theory of filling and evolution of extensional salt-lake basin in East China become perfect.