Morphology, structures and seismic characters of the Chimei Canyon-Fan system offshore eastern Taiwan
Date Issued
2014
Date
2014
Author(s)
Hsieh, Yu-Huan
Abstract
The Chimei submarine canyon is located on the Luzon arc offshore east Taiwan and delivers sediments from Taiwan orogen to deep-sea basin behind the arc to form the Chimei submarine canyon and fan during Taiwan arc-continent collision. The Chimei submarine canyon shows a very distinct morphology and has a wide (9 km on the average) and very smooth bottom. A large submarine fan-valley system was formed at its foot and the northern part of the submarine fan has been eroded. The Chimei submarine canyon starts from the Hsiukuluan River mouth, and runs across the Luzon arc. Meanders in the Chimei fan-valley system follow the Chimei submarine canyon eastward and merges into the Hualien Canyon near the western end of the Ryukyu Trench off NE Taiwan. In this study, we use multichannel seismic reflection profile data together with high resolution bathymetry data to study the topography, basement structures and seismic sequences along the canyon path and in the distal fan. We try to understand how do the Chimei submarine canyon and the Chimei submarine fan-valley form. Based on seismic reflection data, we suggest that sediments were delivered from the orogenic belt into the Huatung Basin across the topographic low of the Luzon arc to form the Chimei submarine canyon-fan system. The Chimei submarine canyon became U-shaped from structural uplift and submarine erosion processes. A series of NNE-SSW trending and east-vergent thrusts run across the Chimei submarine canyon. An larger east-vergent thrust fault lies at the foot of the eastern flank of the Luzon arc, which separates the canyon (over deformation zone) from the fan-valley (over undeformed zone). In spite of many thrusts run across the Chimei submarine canyon, the canyon floor is flat and smooth at the present time. Eight seismic sequences are recognized in submarine fan-valley system. The two lower sequences show sheet-drape and slope-front fill seismic facies which fill the basement low. They are interpreted to be older deep sea sediments deposited before arc-continent collision. The middle sequence shows chaotic and mounded upper fan seismic facies and continuous parallel lower fan seismic facies that were deposited after arc-continent collision. The five upper sequences show a very clear upper fan levee and channel seismic facies that formed during advanced arc-continent collision. We suggest that before arc-continent collision there could be no canyon nor submarine fan formed. Deposition east of the Luzon arc consisted of slope-front sediments. As the Luzon arc began to accrete on the Asian continental margin, sediments were delivered across the topographic low of the Luzon arc, to form the initial Chimei submarine canyon and fan behind the Luzon arc. The Chimei submarine canyon and fan-valley grew from continued sediment supply during advanced arc-continent collision. Part of the submarine fan which deposited on the Luzon arc was uplifted by thrust fault during advanced arc-continent collision. Sediments which deposited on the topographic high of the Luzon arc are folded, while sediments which deposited in the Chimei submarine canyon are faulted. Southern part of the submarine fan behind the topographic high of the Luzon arc was protected from erosion thus better preserved, while northern part of submarine fan at foot of the Chimei submarine canyon has been eroded.
Subjects
Submarine canyon
submarine fan
submarine fan-valley
seismic sequences
seismic reflection profiles
arc-continent collision
eastern Taiwan
SDGs
Type
thesis
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