Sediment Waves Characteristics And Their Formation Mechanism, The Southwest Taiwan Basin, South China Sea

Deep-water sediment waves are widely disseminated in the global continental slope and deep sea basin, mainly results from the interaction of hydrodynamic and marine sediments. Southwest Taiwan Basin, located in northeastern South China, affected by the tectonic basin formed, which developed on a large number of different sizes along the slope of the Canyon, as well as large areas of sediment waves, here’s the ideal range for deep-water sediment waves formation conditions.Detailed analysis of high resolution multi-beam data, and seismic profile data and cores of core data at the bottom in order to reveal the mass of fine particles on the Southwest Taiwan Basin of sediment waves causes. In Northeastern South China Sea (SCS)Southwest Taiwan Basin was identified in two sediment wave fields, mainly restricted by two canyons and Manila trench. Depth of sediment waves between the principle of -2700～-3700 m. Sediments in the North area (21.28°～21.75° N, 119.23°～119.80° E) is located in northeastern SCS down slope, area 1600 km2; South sediment wave zone (20.53°～21.65° N,119.27°～120.08° E) is located in southern Formosa Canyon, west of the Manila trench, an area of 3400 km2.Based on the D-8 algorithm to extract sediment waves ridges, troughs of wave-line, after typical cross-hatching and statistical calculations, find North and South sediment wave zones undulate landforms on wavelengths between 300～5800 m and wave height in the<5～50 m range. Sediment wave length and height are reduced from mainstream sources to the edge, and extends to the Manila trench. The slope between 0～4°, mainly 1°～2°. Aspect with sediments away from the mainstream and capricious.Based on morphological characteristics of sediment waves inversion unconfined turbidity of the seabed conditions, calculating slope through sediment waves to Froude number is obtained between the Fr of 1.55～2.37, namely turbidity as a supercritical fluid, sea flow is in an unstable state. Sediment seafloor turbidity currents flow between 3.46～15.23 m/s. Seismic profile data analysis of sediment waves has to migrate upslope trend, their migration rate in 2-5 m/ka. Shelf edge and deep-water surface sediment particles mainly sand, silt and clay, silts and clay total more than 90%. Bioturbation slope edge, rich in calcium content; more than one cycle of deep-sea sediments, sediment grain size meandering.Through analysis of the sediment waves on the ocean floor in unconfined turbidity result of the hydraulic jumps. Canyon West Penghu unqualified turbidity turn into a supercritical state, under the influence of submarine topography, settlement-oriented flow in a subcritical state, back-flow in a supercritical state to erosion, in a long time and multi-stage muddy stream in Southwest Taiwan Basin is formed by migration of sea undulated topography. South regional sediment waves, though far from the continental slope of the Canyon area, but due to the Formosa canyon and west of north sediment waves field flow confluence of the Canyon effect, and seamounts in the south and southwest of the canyon terrain block makes. Ridges on the south eastern boundary of south sediment waves, with its vertical in the southern section of the canyon, was affected by the overspilled current from canyon.Southwest Taiwan Basin sediments underwater flow is fully reflected the role of topography and regional hydrodynamic interactions consequence.