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
Effect of Lake Level Fluctuations on Turbidite Fan Development in Wang 58 Block
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摘要: 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无水道的滑塌浊积扇体转变.Abstract: 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 cont rol t he development phase of t urbidit e 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. Tur bidite fan with channel is developed in Sha-3 of Upper Chun sub-int erval. In Sha-2, the slump tur bidite 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.