【摘要】 通过对泌阳凹陷核桃园组三段上亚段岩性组合、粒度和地震反射特征的研究,认为深湖区滑塌浊积扇物源来自东北部侯庄辫状河三角洲,其岩性为灰色中砂岩、细砂岩,多夹于深灰色湖相泥岩中,与泥岩呈突变接触,地震剖面显示透镜状反射与前积反射共生,粒度概率曲线具有"低斜一段"式特征。湖平面下降有利于无外界触发机制作用下三角洲前缘滑塌浊积扇的形成。东北部三角洲前缘水体浅,当湖平面下降时,三角洲前缘出露部分因浮力消失而不稳定,可产生局部滑塌。波浪作用可以强烈剥蚀和改造浪基面附近的三角洲前缘沉积,并在波浪的回流作用下进一步形成浊积砂体。滑塌浊积扇均发育在辫状河三角洲和近岸水下扇之间的湖相泥岩中,当三角洲向前推进快、朵叶向前延伸较远时,易形成数量多、面积相对较大的滑塌浊积扇,且距离三角洲朵叶越近,滑塌浊积扇数量越多、面积越大。更多还原

【Abstract】 Analyses of lithology assemblage,grain size and seismic reflection characteristics of the upper third member of Hetaoyuan Formation reveal that the provenance of slump turbidite fan in the deep lake came from Houzhuang braided river delta in the northeast.The slump turbidite fans are characterized by grey medium-fine sized sandstones,interbedding with dark grey lacustrine mudstone in sharp contact,coexistence of lens and progradation reflection on the seismic profile,as well as low slope and one segment of grain-size probability curve. The drop of lake level was favorable for the formation of slump turbidite fan in delta front without external triggering mechanism.As water in northeast delta front was shallow,when the lake level dropped,part of the delta front exposed and lost stability due to the lost of buoyancy,resulting in local slumping.Wave action could strongly corrode and modify delta front sediments near the wave base and resulted in the formation of turbidite sandbody due to wave back flow.All the slump turbidite fans were developed in the lake mudstones between braised river delta and nearshore subaqueous fan.When the delta pushed forward rapidly and the lobes protruded long forward,it was easy to form slump turbidite fans large in both number and area.The number of slump turbidite fans increases and their area enlarges near the delta lobes.更多还原