断陷湖盆洼陷带重力流沉积特征与模式：以南堡凹陷东部东营组为例.docVIP

 断陷湖盆洼陷带重力流沉积特征与模式：以 南堡凹陷东部东营组为例# 鲜本忠，万锦峰* 5 10 15 （中国石油大学（北京）地球科学学院，北京 102249） 摘要：综利用岩心、粒度、测井信息和重力流沉积理论，系统研究了南堡凹陷东部洼陷带东 营组重力流沉积特征和沉积模式。该区重力流沉积砂岩常夹于灰色、灰黑色泥岩中，砂岩相 发育，其中正递变层理（含砾）中-细砂岩（S-3）、粉砂岩相（S-4）和块状层理中-细砂岩 相（S-2）发育层数最多，块状层理含砾砂岩相（S-1）次之；S-2 沉积厚度最大，S-1 和 S-3 次之。 按支撑和沉积机制，将本区重力流分为浊流、砂质碎屑流、颗粒流和液化流，其中 砂质碎屑流以基质支撑、冻结块状沉积为特征。不同重力流发育程度有明显差异。从砂岩层 数看，浊流最多，砂质碎屑流次之，颗粒流和液化流最少；从单期沉积厚度看，砂质碎屑流 最高，平均为 1.17m，浊流沉积最低，仅平均为 0.25m。为了回避取心的局限性、弱化重力 流成因，突出具有油气储集意义的砂层概念，开展了测井岩性解释，结果表明该区重力流沉 积为细砂岩或粉砂岩，单层平均厚度 2.94m，最大厚度可达 9.5m，其中单井中厚度在 3m 以 上的砂体可达 22 层、累积达 107.5m。本区重力流沉积为滑塌成因，除了（扇）三角洲前缘 斜坡的自然滑塌外，断层（地震）活动或间歇式火山喷发是其关键的触发机制；断层活动除 了提供滑塌的动力外，还影响着其堆积场所和沉积的结构。 关键词：重力流沉积；砂质碎屑流；浊流；沉积机制；南堡凹陷 20 Sedimentary characteristics and model of gravity flows deposition in the depressed belt of rift lacustrine basin: An example from Dongying formation in Nanpu depression XIAN Benzhong, WAN Jinfeng 25 30 35 40 45 (Geoscience College, China University of Petroleum (Beijing), Beijing 102249) Abstract: Sedimentary characteristics and depositional model of Dongying formation in depression belt of eastern Nanpu depression were studied based on core, grain size and logging data. The gravity flow sediments, characterized by richness of sandstone lithofacies and lack of conglomerate ones, always interbedded with gray or deep-gray mudstone. According to beds’ number, normal graded bedding sandstone (S-3), siltstone (S-4) and massive bedding sandstone (S-2) were the most developed ones, massive bedding pebbled sandstone (S-1) took the second place. However, S-2 takes the first place in thickness, S-1 and S-3 took the second one. Considering supporting and depositional mechanism, sediment gravity flows in studied area may be divided into four types, i.e. turbidity flow, sandy debris current, grain current and liquified current, and specially, sandy debris current was supported by matrix and deposited by frozen massive mode. Every gravity flow developed differently in large scale. According to sandstone beds’ number, t