| LI Xishuang,LIU Lejun,LI Jiagang,GAO Shan,ZHOU Qingjie,SU Tianyun. 2015. Mass movements in small canyons in the northeast of Baiyun deepwater area, north of the South China Sea. Acta Oceanologica Sinica, 34(8):35－42 |
| Mass movements in small canyons in the northeast of Baiyun deepwater area, north of the South China Sea |
| 南海北部白云深水区东北部小型峡谷内的块体搬运 |
| Received:March 11, 2014 Revised:October 17, 2014 |
| DOI：10.1007/s13131-015-0702-z |
| Key words:mass movement geophysical data trigger mechanism submarine canyon north of the South China Sea |
| 中文关键词: 块体搬运 地球物理数据 触发机制 海底峡谷 南海北部 |
| 基金项目:The National Science and Technology Major Project under contract No. 2011ZX05056-001-02. |
| Author Name | Affiliation | E-mail | | LI Xishuang | The First Institute of Oceanography, State Oceanic Administration, Qingdao 266061, China | lxs@fio.org.cn | | LIU Lejun | The First Institute of Oceanography, State Oceanic Administration, Qingdao 266061, China | | | LI Jiagang | Research Center of China National Offshore Oil Corporation, Beijing 100027, China | | | GAO Shan | The First Institute of Oceanography, State Oceanic Administration, Qingdao 266061, China | | | ZHOU Qingjie | The First Institute of Oceanography, State Oceanic Administration, Qingdao 266061, China | | | SU Tianyun | The First Institute of Oceanography, State Oceanic Administration, Qingdao 266061, China | |
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| Abstract: |
| The process of mass movements and their consequent turbidity currents in large submarine canyons has been widely reported, however, little attention was paid to that in small canyons. In this paper, we document mass movements in small submarine canyons in the northeast of Baiyun deepwater area, north of the South China Sea (SCS), and their strong effects on the evolution of the canyons based on geophysical data. Submarine canyons in the study area arrange closely below the shelf break zone which was at the depth of -500 m. Within submarine canyons, seabed surface was covered with amounts of failure scars resulted from past small-sized landslides. A complex process of mass transportation in the canyons is indicated by three directions of mass movements. Recent mass movement deposits in the canyons exhibit translucent reflections or parallel reflections which represent the brittle deformation and the plastic deformation, respectively. The area of most landslides in the canyons is less than 3 km2. The trigger mechanisms for mass movements in the study area are gravitational overloading, slope angle and weak properties of soil. Geophysical data indicate that the genesis of submarine canyons is the erosion of mass movements and consequent turbidity currents. The significant effects of mass movements on canyon are incision and sediment transportation at the erosion phases and fillings supply at the fill phases. This research will be helpful for the geological risk assessments and understanding the sediment transportation in the northern margin of the SCS. |
| 中文摘要: |
| 大型峡谷内块体搬运及相关的浊流已有广泛的报道,但对于小型峡谷内部类似的作用却鲜有关注.基于地球物理数据,本文详细描述了南海北部陆坡白云深水区东北部的小型峡谷内块体搬运的特征,并讨论了块体搬运对峡谷演化的影响.结果表明,研究区陆架坡折带的水深约-500m,密集排列的海底峡谷便位于坡折带之下的陆坡.在峡谷内部,海底表面崎岖不平,发育由小型滑坡导致的疤痕.块体搬运的三种方向暗示了峡谷内块体运移具有非常复杂的过程.最近的滑坡主要表现出半透明或平行反射,分别代表了峡谷内滑坡具有脆性和塑性两种变形方式.大多数滑坡的面积不超过3 km2.研究区块体搬运的触发机制是沉积物的自重负荷、坡度和弱的土体力学性质.海底峡谷是由块体搬运及其随后的浊流侵蚀而成的.在峡谷的侵蚀阶段,块体搬运对峡谷的影响主要表现在强烈的下切作用和沉积物输送;而在充填阶段,滑坡后的沉积物主要堆积于峡谷内.研究结果有助于研究区的地质风险评估,并对深入了解南海北部陆缘的沉积物输送也有较大的意义. |
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