【来访单位Institution】: 台湾中山大学，台湾 National Sun Yat-sen University, Taiwan

【邀请人Host】: 余凤玲， 副教授

【联络人Contact】:陈敬艳 Chen Jingyan, chenjy@xmu.edu.cn

Abstract:

The source-to-sink characteristics of a very unique sediment-routing system in the world is presented in this review.  The Gaoping River, a small mountainous river having an average gradient of 1:150; and the Gaoping Submarine Canyon that links the river catchment to the deep-sea basin, represent two major topographic features around SW Taiwan. Together, they constitute a terrestrial-to-marine dispersal system that has an overriding impact on source-to-sink transport of sediment in this region. The Gaoping Submarine Canyon extents from the mouth of the Gaoping River through the shelf and slope, and merges into the northeastern Manila Trench over a distance of about 260 km. It is a major conduit for the transport of terrestrial sediment and carbon to the South China Sea and the landward transport of particles of marine and biological origins.

In the Gaoping Submarine Canyon the normal mode of transport of suspended sediment is dominated by tidal oscillations, and the net direction is up-canyon. In contrast, sediment transport associated with episodic gravity-driven events is down-canyon.  The steady sedimentation of the tidal regime results in hemipelagic mud on the canyon substrate.  The gravity-driven hyperpycnal regime creates turbidites in the canyon.

Typhoon-induced river floods often lead to hyperpycnal plumes at the river mouth, which directly and indirectly ignite hyperpycnal turbidity currents in the canyon forming an effective agent to transport large amounts of terrestrial sediment and organic carbon (modern and fossil) to the South China Sea basin. Therefore, the Gaoping River-Gaoping Submarine Canyon represents a type of source-to-sink system in which terrestrial sediment in a mountainous catchment is promptly removed and transported to the river mouth by fluvial processes, and then efficiently and quickly transported to the deep sea by turbidity currents along a submarine conduit during episodic typhoon events.  This is also a pathway by which modern terrestrial organic carbon could be quickly and effectively delivered to the deep sea leading to quick burial and sequestration.