Submerged karst landforms observed by multibeam bathymetric survey in Nagura Bay, Ishigaki Island, southwestern Japan
Submerged karst landforms observed by multibeam bathymetric survey in Nagura Bay, Ishigaki Island, southwestern Japan
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DOI：
10.1016/j.geomorph.2014.07.032
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发表时间：
2015-01
期刊：
影响因子：
3.9
通讯作者：
H. Kan;K. Urata;M. Nagao;N. Hori;K. Fujita;Y. Yokoyama;Y. Nakashima;Tomoya Ohashi;K. Goto;A. Suzuki
中科院分区：
文献类型：
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作者：
H. Kan;K. Urata;M. Nagao;N. Hori;K. Fujita;Y. Yokoyama;Y. Nakashima;Tomoya Ohashi;K. Goto;A. Suzuki
日本琉球群岛南部石垣岛上的名古拉湾发现了淹没的热带喀斯特地貌。在第四纪海平面低水位时期，浅层以下的沿海海底遭受了反复交替的陆上冲刷和沉积。我们在名古拉湾中心区(1.85米×22.7公里)进行了宽带多波束测量，并在1.6-58.5米的深度范围内可视化了高分辨率的测深结果。在海湾内发现了各种类型的湿润热带喀斯特地貌，包括河流岩溶、漏斗岩溶、驾驶舱岩溶、多边岩溶、乌瓦拉和巨型漏斗。虽然这些淹没的喀斯特地貌被厚厚的冰后生物礁和礁石沉积物覆盖，但它们的形状和大小与与珊瑚礁地貌有关的地貌不同。名仓湾的水下景观可能是在多个冰期和间冰期形成的。根据我们的水深测量结果和沿海地区的航拍照片，这一淹没的喀斯特景观似乎已经发育到整个名古拉湾(即大约6×15公里的面积)，是日本最大的淹没喀斯特。
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.