辽河盆地滩海地区东营组沉积特征与演化

Sedimentary features and evolution of the Dongying Formation in the tidal area of the Liaohe Basin

综合岩心、钻井、地震等资料,运用现代沉积学的思路和方法,对辽河盆地滩海地区古近系东营组沉积体系特征进行了分析,认为在东营组沉积时期滩海地区共发育扇三角洲、辫状河三角洲、三角洲、湖泊、滩坝以及湖底扇6种沉积类型。沉积体系的时空分布和演化特征受控于构造背景和湖平面变化。东营组三段沉积时期盆地沉降幅度大,为湖盆扩张早期,研究区沉积相以扇三角洲,辫状河三角洲、湖底扇为主;东营组二段沉积时期为湖盆扩张时期,但构造活动减弱,湖盆变浅,研究区沉积相以辫状河三角洲及滨浅湖-滩坝为主;东营组一段沉积时期为湖盆收缩期,除局部深凹为滨浅湖-滩坝沉积外,广泛发育辫状河三角洲沉积。

An analysis was carried out on the sedimentary features of the Paleogene Dongying Formation in the tidal area of Liaohe Basin based on core, drilling and seismic data as well as modern sedimentology concepts and methods. Six sedimentation types are identified in the Dongying Formation in the tidal area, namely fan delta, braided delta, delta,lake, beach bar and sublacustrine fan. The temporal and spatial distribution as well as the evolutionary features of the sedimentary system in the Formation was controlled by the structural background and lake level variation. The third member of the Formation was deposited in the early stage of lake expansion when the basin was experiencing the most intense subsidence. The sedimentary facies are dominated by fan delta, braided deha and sublacustrine fan. The second member was formed during the lake expansion when the tectonic movement weakened and the lake basin was shallower. Sedimentary facies during the time were mainly braided delta and shallow lake-beach bar. The first member was deposited during lake shrinking and braided delta dominated except for shallow lake-beach bar in local deep sags.