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周期性阶坎的特征及其对深水沉积研究的意义

作    者:许小勇1, 吕福亮1, 王大伟2, 王 彬1, 孙 辉1, 邵大力1, 鲁银涛1, 马宏霞1
单    位:1 中国石油杭州地质研究院; 2 中国科学院深海科学与工程研究所
基金项目:受国家自然科学基金项目“琼东南盆地深水重力流沉积旋回演化规律与形成机理”资助
摘    要:
周期性阶坎(Cyclic Steps)是指浊流沉积中的长波状(波长/波高?垌1)且向上游迁移的高流态底形,以内水跃为界,在海底陡坡和坡折位置常见。回顾了周期性阶坎及相关的超临界浊流底形研究的现状,并以高分辨率多波束测深数据和地震资料为基础,重点介绍了美国、加拿大、及中国南海地区发育的周期性阶坎特征,同时展示了加拿大斯阔米什前三角洲的浊流监测情况和数值模拟结果,讨论了周期性阶坎形成的控制因素和分布范围。通常,发育在活跃海底峡谷-水道内的周期性阶坎相对较小(波长几十米,波高几米),而发育在非受限的天然堤漫溢区和水道-朵体过渡带的周期性阶坎相对较大(波长上千米,波高上百米)。周期性阶坎等超临界浊流底形对陆坡区深水沉积的发育具有重要影响,开展相关研究有助于更好地理解水道-天然堤沉积体系的形成和演化过程,对深水油气储层结构的研究和预测具有指导意义。
关键词:周期性阶坎; 超临界浊流; 底形; 深水沉积

Cyclic steps and significance to deep water sedimentation

Author's Name: XU Xiaoyong, Lü Fuliang, WANG Dawei, WANG Bin, SUN Hui, SHAO Dali, LU Yintao, MA Hongxia
Institution: PetroChina Hangzhou Research Institute of Geology,
Abstract:
Cyclic steps refer to the bedforms of long-wave(the ratio of wavelength to wave height ?垌1), migrating upstream and being upper-flow-regime in turbidity current. They are bounded by internal hydraulic jump and commonly occur at steep slopes and slope breaks. This paper reviews the research status of cyclic steps and other related supercritical bedforms. Three examples from continental margins in United States, Canada, and South China Sea are presented based on high-resolution multi-beam sonar data and seismic data. This paper also present the results of monitoring and numerical modeling of turbidity currents in the Squamish prodelta, British Columbia, Canada. The controlling factors and the distribution of cyclic steps were discussed based on numerical modeling. The cyclic steps in active submarine canyon-channel system are relatively small (tens of meters in wavelength and few meters at height), while the cyclic steps in the unconfined levee system and the channel-lobe transition zone are relatively larger (above one kilometer in wavelength and hundreds of meters at height). Cyclic steps and related supercritical turbidity bedforms may have important influence for the deep water sediments in slope area, which can help to better understand the evolution of deep water channel-levee system, and to predict the oil and gas reservoirs of deep water.
Keywords: cyclic steps; supercritical current; bedforms; deep water sediments
投稿时间:2017-11-12  
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