陆相湖盆古地形、可容空间的体积变化率与层序结构的关系

通过对东营凹陷和东濮凹陷的层序结构的差异进行了对比,并对东营凹陷和东濮凹陷的体积和地形进行了分析,认为陆相湖盆古地形、可容空间变化与总可容空间的比值(可容空间的体积变化率)与层序结构有密切关系。沙三段沉积期,东营凹陷三级湖平面变化引起的可容空间的体积变化率与东濮凹陷四级湖平面变化引起的可容空间的体积变化率相近。东营凹陷沙三段沉积时期盆地体积大、地形陡,层序的发育主要受三级湖平面变化的控制,因此层序厚度大,层序内部砂体厚度大,分布相对集中。而东濮凹陷沙三段沉积时期,盆地体积小,地形较缓,层序的发育主要受四级湖平面变化的控制,因此层序厚度小,层序内部砂体厚度小,分布广,不稳定。

Relationship between Paleotopography and Volumetric Change Rate of Lacustrine Basin to the Sequence Structure

Through the comparison of the difference sion, and the analysis of basin volume and topograph of sequence structure in Dongying depression and Dongpu depresy of Dongying depression and Dongpu depression, it is considered that the paleotopography of basin, the ratio of the accommodation added to the total accommodation are nearly related to the sequence structure. During the sedimentation of the third member of Shahejie Formation, the variation rate of accommodation added and created by the third order cycle lake level fluctuation in Denying depression are nearly equal to the variation rate of accommodation added and created by the fourth order cycle lake level fluctuation in Dongpu depression. During the sedimentation of third member of Shahejie Formation, the basin volume of Dongying depression is very large and the slope is very steep, and the development of sequence is controlled by third order cycle lake level change, so the sequence is very thick. The sandbody thickness in the sequence is also big, and its distribution is very concentrative. During the sedimentation of the third member of Shahejie Formation, the basin volume of Dongpu depression is very small, the topography is very gentle, and the developmemt of sequence is controlled by fourth order cycle lake level change, so the thickness of its sequence is small, and the sandbody thickness in the sequence is small too. Its distribution is very wide and is not stable.