Seismic and morphological characteristics of the Kaohsiung submarine Canyon, southwestern Taiwan

Abstract

The Kaohsiung Canyon, the smallest of the submarine canyons on the southwestern Taiwan margin, extends from the shelf edge along a straight course on the upper slope to the 700 m isobath. Multichannel seismic profiles reveal the seismic characteristics and infer the sedimentary processes forming the canyon. In the upper canyon, the seismic profiles reveal slumping features and the termination of parallel reflectors against the steep canyon walls, suggesting erosional canyon downcutting. In the lower canyon segments, seismic configurations illustrate relatively flat reflectors onlapping the canyon bottom, resulting from sediment infilling. Two types of canyon fills are recognized: a chaotic fill and a mounded onlap fill, both suggesting gravity mass transport. On the basis of seismic interpretations, this canyon can be divided into two parts: an upcanyon erosional zone and a downcanyon mixed depositional and erosional zone. The course of the Kaohsiung Canyon is remarkably short and straight but with no distributaries as compared to the adjacent long and sinuous Kaoping Canyon. The cross-sectional morphology changes from V-shaped in the upcanyon sections (erosional zone) to U-shaped in the downcanyon sections (depositional and erosional zone). The seismic data provide no evidence for a fault zone along the canyon course. Rather, downslope submarine excavation is the major process forming the canyon.