Links among slope morphology, canyon types and tectonics on passive and active margins in the northernmost South China Sea

Abstract

We examine slope profile types and variations in slope gradient and slope relief with depth for both passive and active margins in the northern most South China Sea. The passive South China margin is characterized by an exponential slope profile, mainly associated with clustered slope-confined canyons. The active Taiwan margin shows a linear-like shape with great variations along the lower slope. Fewer canyons occur on the Taiwan margin, and hence the influence of canyon incision on slope morphology is relatively less significant. Quantitative analyses of slope curvature, slope gradient and square root of relief variance are useful statistical parameters to explain characteristics and variability of morphology of the slope of the South China margin, but not for the Kaoping slope on the Taiwan side. On the active Taiwan margin, tectonic activities are dominant over sediment deposition and surface erosion, producing a slope profile quite different from those of passive margins of the Middle Atlantic, KwaZulu-Natal, South Africa where failure on slope and accompanying canyon incision are the dominant processes shaping the slope morphology.