湖平面变化对王58地区浊积扇形成与演化的控制作用研究

在陆相断陷盆地内，湖平面变化、构造作用等外部因素对浊积扇体的形成与演化有明显的控制作用。以东营凹陷南斜坡王58地区沙四上浊积扇为例，分析了湖平面变化对浊积扇发育的控制作用。湖平面变化控制了沉积物供给，从而控制了扇体的发育期次。研究区纯上4砂组沉积时期，湖平面相对较低，研究区浊积扇体并不发育；浊积扇体发育在纯上2、3砂组沉积时期；纯上1砂组沉积时期，湖平面上升，研究区不再发育浊积扇。海平面变化控制了沉积物供给，控制了浊积扇体的发育类型。在纯上3砂组沉积时期，水体较浅，发育带水道的浊积扇；在纯上2砂组沉积时期，湖水较深，发育无水道的滑塌浊积扇。总之，随着湖平面的变化，王58地区沙四上浊积扇经历了从出现、发展直到消亡的整个过程，并且随着湖平面的变化，扇体由带水道的浊积扇体向元水道的滑塌浊积扇体转变。

Effect of Lake Level Fluctuations on Turbidite Fan Development in Wang 58 Block

In continental rift-subsidence basin, external parameters, such as lake level fluctuations and tectonic movement, have an obvious effect on the development of turbidite fan. Taking the Upper Sha-4 turbidite fan in Wang-58 block as an example, we explain how lake level fluctuations control the development of turbidite fan. Lake level fluctuations control the development phase of turbidite fan through controlling sediment supply. In the study area, turbidite fan develop in Sha-2 and Sha-3 of Upper Chun sub-interval, not in Sha-1 and Sha-4 because the lake level lower down or rise up. Lake level fluctuations also control the type of developed turbidite fan. Turbidite fan with channel is developed in Sha-3 of Upper Chun sub-interval. In Sha-2, the slump turbidite fan without channel is developed because of deep water. In a word, the development of turbidite fan of Upper Chun sub-interval of the Es4 member in Wang-58 block involves appearing, growth, and disappearing. Furthermore, the turbidite fan changes from channel type to slump fan according to lake level fluctuations.