北部湾盆地福山凹陷古近纪湖底扇沉积演化及模式探讨  

A discussion on the Palaeogene sublacustrine fan of Fushan depression in Beibuwan basin, northern South China Sea

作　　者：刘丽军[1] 莫申国[2] 佟彦明 

机构地区：[1]中国地质大学能源地质系,北京100083 [2]中国科学院地理所资源环境信息系统国家重点实验室,北京100101 [3]中国海洋石油研究中心南海西部研究院,广东湛江524057

出　　处：《岩石矿物学杂志》2003年第2期138-142,共5页Acta Petrologica et Mineralogica

基　　金：中国石油天然气集团公司重点科技攻关资助项目

摘　　要：综合应用地震、测井及岩心观察资料 ,对福山凹陷古近纪流沙港组的湖底扇沉积进行了详细研究。认为该期的湖底扇沉积主要是由于三角洲前缘带的砂体在重力作用下进入湖泊深水区堆积而形成 ,部分是由位于湖盆陡坡边缘的河道砂沿水下河道进入湖泊深水区而形成的水下重力流沉积。从空间分布来看 ,湖底扇主要分布在凹陷的北部和西部 ,且北部和西部湖底扇的扇体规模较东部大 ,存活时间较东部长。平面上湖底扇位于三角洲体系的外侧 ,垂向上由下至上发育着从湖底扇—三角洲前缘远端—三角洲前缘近端的沉积演化序列。湖底扇的总体沉积模式为南部的辫状河三角洲砂岩碎屑体向北推进至深湖区形成孤立的、规模相对较大的湖底扇砂体 ;Based on seismic survey, well logging and core observation, this paper interprets the sublacustrine fan of Liushagang Formation in Fushan depression. The formation of the sublauctrine fun can be attributed to two factors: the main factor is that the front of the delta entered the deep lake area along the southern slope under the action of the gravity. The second factor is that the channel sand close to the steep margin of the basin entered the deep lake area along the underwater channel, forming the gravity flow sedimentary underwater. Due to the different tectonic backgrounds and the degrees of material supply, the sublacustrine fan was mainly distributed in L1 and L2 periods, but was not well developed during L3 period. Viewed from spatial distribution, the sublacustrine fan was mainly developed in the northern and western parts, and the eastern part only possesses the secondary importance in this aspect. The extent of the fan in the north and the west is greater than that in the east, and the duration of the fan in the north and the west is also longer than that in the east. At the surface, the sublacustrine fan is distributed on the outer edge of the delta regime, and the sedimentary evolutionary sequence is in upward succession from sublacustrine fan through distal end of delta front to proximal end of delta front. The general sedimentary model of sublacustrine fan is like this: abundant braided delta sandstone migrated from the south to the north, deposited in the deep lake, and formed an isolated and big sublacustrine sandbody. The secondary material sources from the west and the east formed the sublacustrine fan in the deep lake under the control of the main active faults in the east and the west.

关 键 词：北部湾盆地 福山凹陷 古近纪 湖底扇 沉积演化 

分 类 号：P512.2[天文地球—地质学] P534.611