TY - JOUR
T1 - Submerged karst landforms observed by multibeam bathymetric survey in Nagura Bay, Ishigaki Island, southwestern Japan
AU - Kan, Hironobu
AU - Urata, Kensaku
AU - Nagao, Masayuki
AU - Hori, Nobuyuki
AU - Fujita, Kazuhiko
AU - Yokoyama, Yusuke
AU - Nakashima, Yosuke
AU - Ohashi, Tomoya
AU - Goto, Kazuhisa
AU - Suzuki, Atsushi
N1 - Funding Information:
This study was supported by the Japan Society for the Promotion of Science (JSPS) through a Grant-in-Aid for Scientific Research (A) ( Nos. 22240084 and 25242026 ; chief investigator: H. Kan). The broadband multibeam echosounder (Sonic 2022) was introduced to HK's laboratory using the above-mentioned grant #22240084. We would also like to express our appreciation for Shin Takada and Kouichi Nakano of the Toyo Corporation for technical support with R2 Sonic 2022. Field surveys were supported by the following people: Tateru Yarabu and Minoru Uehara, who steered the research boat; Ken'ichi Togashi, who assisted with the SCUBA diving surveys; and Tsuguo Chimura of the Chuo Kaihatsu Co. Ltd., who assisted with the drilling survey. Akira Maekado kindly provided information regarding limestone corrosion in the Ryukyu Islands. The constructive comments of Davide Baioni and two anonymous reviewers and the editor Jo De Waele helped to improve this contribution.
Publisher Copyright:
© 2014.
PY - 2015/1/5
Y1 - 2015/1/5
N2 - Submerged tropical karst features were discovered in Nagura Bay on Ishigaki Island in the southern Ryukyu Islands, Japan. The coastal seafloor at depths shallower than ~. 130. m has been subjected to repeated and alternating subaerial erosion and sedimentation during periods of Quaternary sea-level lowstands. We conducted a broadband multibeam survey in the central area of Nagura Bay (1.85. ×. 2.7. km) and visualized the high-resolution bathymetric results over a depth range of 1.6-58.5. m. Various types of humid tropical karst landforms were found to coexist within the bay, including fluviokarst, doline karst, cockpit karst, polygonal karst, uvalas, and mega-dolines. Although these submerged karst landforms are covered by thick postglacial reef and reef sediments, their shapes and sizes are distinct from those associated with coral reef geomorphology. The submerged landscape of Nagura Bay likely formed during multiple glacial and interglacial periods. According to our bathymetric results and the aerial photographs of the coastal area, this submerged karst landscape appears to have developed throughout Nagura Bay (i.e., over an area of approximately 6. ×. 5. km) and represents the largest submerged karst in Japan.
AB - Submerged tropical karst features were discovered in Nagura Bay on Ishigaki Island in the southern Ryukyu Islands, Japan. The coastal seafloor at depths shallower than ~. 130. m has been subjected to repeated and alternating subaerial erosion and sedimentation during periods of Quaternary sea-level lowstands. We conducted a broadband multibeam survey in the central area of Nagura Bay (1.85. ×. 2.7. km) and visualized the high-resolution bathymetric results over a depth range of 1.6-58.5. m. Various types of humid tropical karst landforms were found to coexist within the bay, including fluviokarst, doline karst, cockpit karst, polygonal karst, uvalas, and mega-dolines. Although these submerged karst landforms are covered by thick postglacial reef and reef sediments, their shapes and sizes are distinct from those associated with coral reef geomorphology. The submerged landscape of Nagura Bay likely formed during multiple glacial and interglacial periods. According to our bathymetric results and the aerial photographs of the coastal area, this submerged karst landscape appears to have developed throughout Nagura Bay (i.e., over an area of approximately 6. ×. 5. km) and represents the largest submerged karst in Japan.
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U2 - 10.1016/j.geomorph.2014.07.032
DO - 10.1016/j.geomorph.2014.07.032
M3 - Article
AN - SCOPUS:85027943083
SN - 0169-555X
VL - 229
SP - 112
EP - 124
JO - Geomorphology
JF - Geomorphology
ER -