今天是2019年08月19日

南海南部沉积物波:软变形及其触发机制

DOI:10.3799/dqkx.2018.303

作者:王龙樟,姚永坚,林卫兵,徐行,肖娇静,沈奥,徐乔

联系地址:中国地质大学海洋学院,湖北武汉 430074

摘要:目前,沉积物波的成因还是存在很多争议.通过详细的地震资料解释,发现南海南部海域有一个规模巨大的海底滑坡,滑坡体长达160 km.从剖面上看,滑坡体结构完整,由减损带、加积带、滑阻带、破坏体、滑脱面、滑坡后壁、冠上裂缝、横向裂缝等结构要素组成.在如此低的海底坡度(仅0.3°~0.5°)上形成如此大规模的滑坡体,推测是地震活动触发的.加积带内发育沉积物波.形态特征和剪应力分析显示,沉积物波形成于减损带的推挤作用.加积带中部推力最大,导致下部为逆时针剪切,上部为顺时针剪切.因此,沉积物波属于海底滑坡引起的软沉积物变形.软变形沉积物波是海底滑坡的一种特殊标志,因此这项研究有助于发现海底滑坡,也有助于海底工程的减灾防灾工作.

关键字:南海南部;沉积物波;软变形;海底滑坡;触发机制;沉积学.

Sediment Waves in the South of South China Sea: Soft Sediment Deformation and Its Triggering Mechanism

Author:Wang Longzhang, Yao Yongjian, Lin Weibing, Xu Xing, Xiao Jiaojing, Shen Ao, Xu Qiao

Author Address:College of Marine Science and Technology , China University of Geosciences, Wuhan 430074, China

Abstract:At present, the cause of sediment waves is still controversial. Detailed interpretation of the seismic profiles in the south of South China Sea, supports the discovery of an enormous submarine landslide, which covers a distance of 160 km. Analyzed from the seismic profiles, the landslide body consists of depletion zone, accumulation zone, main scarp, crown scarp, rupture surface, separation surface and transverse cracks. The submarine landslide was triggered by earthquake activity, according to the very low seabed slope (only 0.3°~0.5°) and the enormous scale of the landslide body. The sediment waves are common in the accumulation zone. Based on morphological characteristics and shearing stress analysis, the sediment waves formed through the compression of the depletion zone with a maximum stress in the middle part, leading to counterclockwise shearing in the lower part and clockwise shearing in the upper part. Therefore, the sediment waves are soft sediment deformation caused by submarine landslide. Soft deformation sediment wave is a special mark of submarine landslide, and this study promotes the discovery of submarine landslide and also contributes to the disaster reduction and prevention of submarine engineering.

Keyword:the south of South China Sea; sediment waves; soft sediment deformation; submarine landslide; triggering mechanics; sedimentology.

 

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作者简介:王龙樟(1965-),男,教授,主要从事海洋地质和油气地质的教学与研究工作.ORCID:0000-0003-2885-7690.E-mail: longz_wang@cug.edu.cn.

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