Sedimentological characteristics and seafloor failure offshore SW Taiwan

  • Author(s): Chih-Chieh Su, Sheng-Ting Hsu, Huai-Houh Hsu, Jing-Yi Lin, and Jia-Jyun Dong
  • DOI: 10.3319/TAO.2017.06.21.01
  • Keywords: Sedimentation rate, Sediment budget, Submarine canyon, Seafloor failure, Pb-210
  • Spatial distribution and characteristics of sediments off SW Taiwan
  • Re-evaluated the sediment budget and impact of event-driven sedimentation process
  • Identified the feature of mass slope failure on the Upper Gaoping Slope
Abstract

In this study, analysis results reveal two main deposition zones are located at the flank of upper Gaoping Submarine Canyon and Lower Fangliao Basin offshore SW Taiwan. The non-event related sediments deposited in past 150 years (i.e., 632 Mt/km2) was delivered and transported from Gaoping River by suspension process with tides and coastal currents and gradually spread out offshore. Meanwhile, the total mass of accumulation sediments is 1922 Mt/km2, accounting for 40% Gaoping River’s sediment load and suggesting that the deposition process is mainly controlled by natural hazards. Sedimentation ratesin much of the study area, except in the main deposition zones, are less than 0.5 cm/yr (5 m/kyr). Compared with the studies at the instability seafloor caused by high sedimentation rates (~30 m/kyr), the offshore southwestern Taiwan is relatively stable. In this study, we also discovered a series of sediment waves located on the upper continental slope between Gaoping and Fangliao Submarine Canyons which is related to the creeping process on seafloor. In summary, our results reveal the fluid activities, existence of weak layers and earthquake triggering are potential factors which might induced seafloor failures offshore southwestern Taiwan.

 

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