Do equilibrium conditions exist during sediment transport studies on continental margins? An example from the East China Sea

Analysis of high-resolution (<1 m) GeoPulse seismic reflection and Chirp sonar data from the continental margin of the East China Sea reveals the presence of a thin (1- to 5-m-thick) sediment veneer over a highly reflective transgressive surface. Due to reverberation of the output signal and the effect of the bubble pulse, this veneer may erroneously be interpreted as a laterally continuous feature. Sonar data, which does not suffer from these ghosting effects, reveals that the sea bottom is often an erosional surface that exposes older, relict sediments, which were deposited under a radically different hydrodynamic regime than exists in these locations today.