Research Article| May 01, 2008 Physiographical and sedimentological characteristics of submarine canyons developed upon an active forearc slope: The Kushiro Submarine Canyon, northern Japan Atsushi Noda; Atsushi Noda † 1Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology, Central 7, 1-1-1Higashi, Tsukuba, Ibaraki 305-8567, Japan †E-mail:a.noda@aist.go.jp Search for other works by this author on: GSW Google Scholar Taqumi TuZino; Taqumi TuZino 1Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology, Central 7, 1-1-1Higashi, Tsukuba, Ibaraki 305-8567, Japan Search for other works by this author on: GSW Google Scholar Ryuta Furukawa; Ryuta Furukawa 1Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology, Central 7, 1-1-1Higashi, Tsukuba, Ibaraki 305-8567, Japan Search for other works by this author on: GSW Google Scholar Masato Joshima; Masato Joshima 1Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology, Central 7, 1-1-1Higashi, Tsukuba, Ibaraki 305-8567, Japan Search for other works by this author on: GSW Google Scholar Jun-ichi Uchida Jun-ichi Uchida 2Department of Earth Science, Faculty of Science, Kumamoto University, 39-1, Kurokami 2-chome, Kumamoto 860-8555, Japan Search for other works by this author on: GSW Google Scholar GSA Bulletin (2008) 120 (5-6): 750–767. https://doi.org/10.1130/B26155.1 Article history first online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Atsushi Noda, Taqumi TuZino, Ryuta Furukawa, Masato Joshima, Jun-ichi Uchida; Physiographical and sedimentological characteristics of submarine canyons developed upon an active forearc slope: The Kushiro Submarine Canyon, northern Japan. GSA Bulletin 2008;; 120 (5-6): 750–767. doi: https://doi.org/10.1130/B26155.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract Comprehensive geological surveys have revealed the physiographical and sedimentological characteristics of the Kushiro Submarine Canyon, one of the largest submarine canyons around Japan. The canyon indents the outer shelf along a generally straight, deeply excavated course of more than 230 km in length upon the active forearc slope of the Kuril Trench in the Northwest Pacific. The forearc slope has a convex-upward geometry that can be divided into upper and lower parts separated by an outer-arc high (3200–3500 m water depth). The upper slope consists of gently folded forearc sediments, and the lower slope is underlain by sedimentary rocks deformed by subduction-related processes. The upper reaches of the canyon (~3250 m of thalweg water depth) are developed on the upper slope, showing a weakly concave-upward longitudinal profile with a gradual down-canyon increase in relief between the thalweg and the canyon rim. Although an infill of hemipelagic mud and the absence of turbidite deposits indicates that the upper part of the upper reaches of the canyon (~900 m thalweg water depth) is inactive, the lower part of the upper reaches (900–3250 m thalweg water depth) is considered to be an active conduit to the lower reaches, as determined from voluminous turbidites recovered in sediment cores (~76-yr intervals) and rockfalls observed in the canyon bottom by deep-sea camera. A number of gullies developed upon the northern slope of the lower part of the upper reaches might well provide a frequent supply of turbidity currents, giving rise to a down-canyon increase in the frequency of flow events. The down-canyon increase in flow occurrence is related to a gradual decrease in gradient, demonstrating an inverse power-law relationship between slope and drainage area. In contrast, the lower reaches of the canyon (3250–7000 m thalweg water depth) are characterized by a gradual decrease in relief, a high gradient, and extremely low sinuosity. The limited increase in drainage area down-canyon of the confluence with the Hiroo Submarine Channel, which is the largest tributary of the main canyon, indicates that the erosional force of turbidity currents decreases down-canyon. The gradient of the lower reaches largely reflects the morphology of the forearc slope along the canyon, which has been deformed by subduction-related tectonics. The lack of an inverse power-law relationship between gradient and drainage area in the lower canyon supports the hypothesis that the topography of the lower reaches is dominated by subduction-related tectonic deformation of the substrate rather than canyon erosion. Interrelationships between canyon erosion by currents and tectonic processes along the forearc slope are important in the development of the physiography of submarine canyons upon active forearc margins. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.