Sedimentary erosive processes and sediment dispersal in Kaoping submarine canyon

The Kaoping submarine canyon, connected to the Kaoping River in the coastal plain in SW Taiwan, continues the dispersal path of modern Kaoping River sediments, from an active small mountainous drain basin to the receiving basin of the South China Sea. Using seismic reflection sections, Chirp sonar profiles, and bathymetric mapping, we reveal characteristic erosive processes responsible for multiple cut-and-fill features, deeply entrenched thalweg, and sediment dispersal that are closely related to turbidity currents in the canyon. The river-canyon connection setting, along with extreme climatic conditions and active tectonism, is favorable for generation of turbidity currents at the canyon head. The upper reach of the Kaoping Canyon is distinguished into three distinct morpho/sedimentary features. The canyon head is characterized by V-shaped axial thalweg erosion. The sinuous segment of the upper reach is dominated by a deeply incised canyon pathway with trough-like morphology. Relatively small-scaled features of cut-and-fill associated with the dominant incision process are commonly along the canyon floor, resulting in a flat-floored pathway. Sliding and slumping dominated the steep canyon walls, producing and transporting sediments to canyon floor and partially filling up canyon thalweg. The meandering segment is characterized by erosive features where deeply down-cutting occurs in the outer bend of the major sea valley, forming V-shaped entrenched thalweg. The recurrences of turbidity currents have allowed continuous incision of the canyon head and have kept the connection between the canyon head and the river mouth during Holocene highstand of sea level. The upper reach of the Kaoping Canyon is linked to drainage area and maintains as a conduit and/or sink for terrigenous and shallow marine material. Sediment-laden river plume operates in the Kaoping River-Canyon system, with turbidity currents flushing river sediments into the canyon head where the canyon thalweg is the most erosive. Presently, the upper reach of the Kaoping Canyon can be considered as a temporal sediment sink.