Citation: | WANG Yifan, SU Zheng, SU Ming, WANG Hongbin, SHA Zhibin, LIANG Jinqiang, LIU Jie. SEDIMENT FAILURES IN THE SHENHU AREA, NORTHERN CONTINENTAL SLOPE OF THE SOUTH CHINA SEA[J]. Marine Geology & Quaternary Geology, 2017, 37(5): 184-194. doi: 10.16562/j.cnki.0256-1492.2017.05.019 |
With the seismic data acquired by the Guangzhou Marine Geological Survey, we studied the types and characteristics of the frequently developed sediments failures in the Shenhu area of the northern South China Sea. The distribution pattern of sediment failures is adopted to reveal the relationship between slope-confined submarine canyons and sediment failures. The sediments failures in the study area can be grouped to two types. The first type, which is mainly located at the ridges in the lower reach of a canyon and hardly affected by seafloor geomorphology, is characterized by multiple continuous wavy reflectors in a pattern of southwards mass movement. The second type is mainly the products of the mass movement from the ridge to the bottom of a canyon, and is obviously affected by the topography of the canyons. At the head of a canyon, sediment failures always occur as slides with continuous reflectors. And in the middle reach there is intensive deformation and dominated by slumps. From the lower reach to the canyon mouth, however sliding/slumping blocks dominate. Since Quaternary, Great amount of sediment charges come from the Pearl River system towards the north. With the help of steep seafloor topography, the activity of sediment failures is accelerated. Sediment re-deformation may widely occur in submarine canyons. In addition, the vertical migration of gas-bearing fluids coming from gas hydrate is also an important factor for sediment instabilities in the study area.
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(a) Location map of the Shenhu Area on the northern continental slope of the South China Sea; (b) Seafloor topography of the study area with 17 slope-confined submarine canyons
Seismic reflections of the sediment failures in the Shenhu Area
Distribution of sediment failures located between 9th to 11th submarine canyons in the Shenhu Area
Segmentation of the 9th submarine canyon in the Shenhu Area
Sediment failures at the head of upper reach of the 10th submarine canyon
Sediment failures at the head of upper reach of the submarine canyon
Sediment failures at the middle reach of the submarine canyon
Sediment failures at the lower reach to the mouth of a submarine canyon
Sediment failures at the lower reach to the mouth of the submarine canyon
Sediment failures at the ridge of the 10th submarine canyon
Prograding shelf-edge deltas and associated clinoforms in the northern part of the Shenhu Area
The slope gradients of the seafloor in the Shenhu Area
Linkage between fluids escape and sediment failures in the Shenhu Area