Structure and Sediment Distribution in the Continental Margin South of the Dongsha Island, South China Sea
Date Issued
2009
Date
2009
Author(s)
Chen, Cheng-Yi
Abstract
In this study, we use multi-channel seismic reflection data to investigate shallow geological structures and sediment distribution in the continental margin and northern South China Sea Basin south of the Dongsha Island and discuss the relationships between the sediment distribution and geologic structures observed.rom the seismic profiles, we have identified many normal faults, volcanic bodies and igneous basement in the study area. Most of the normal faults are distributed in the continental slope and in the abyssal plain; they were formed in the syn-rift crust when seafloor spreading of the South China Sea was active. The volcanic rocks are distributed near the foot of the continental slope. They were formed by magma upwelling from the mantle after the seafloor spreading activities of the South China Sea had ceased.he sediment thickness were determined by identifying the basement depth along each of the seismic profiles, then an isopach map was generated. Velocity information derived from ocean-bottom seismometer data were used to estimate the P-wave velocity profile of the study region. We use this function to convert the sediment isopach map from two-way travel time (second) to depth (meter).rom the isopach map compiled in this study, the sediment thicknesses vary between 250~3400 meters, and the sediment distribution was largely affected by the development of small basins formed due to normal faulting and volcanic activities. The sediment isopach map shows three areas in the study region where thick sediments are present. One of them is the South China Sea abyssal plain where influence of the Manila Trench subduction is apparent. Another one located to the west of the Dongsha Island is the Pearl River Mouth Basin. The third area is located in the continental slope south of the Dongsha Island, where small basins formed by the normal faults in the landward side and uplifted volcanic rocks near the bottom of the continental slope.
Subjects
sediment isopach map
reflection seismic
continental margin
Dongsha Island
Type
thesis
File(s)![Thumbnail Image]()
Loading...
Name
ntu-98-R95241308-1.pdf
Size
23.53 KB
Format
Adobe PDF
Checksum
(MD5):80c0802d4604ecc7f25b2d4c9095c9ed