TY - JOUR
T1 - Rapid subsidence of the Kikai Seamount inferred from drowned Pleistocene coral limestone
T2 - Implication for subduction of the Amami Plateau, northern Philippine Sea
AU - Nakazawa, Tsutomu
AU - Nishimura, Akira
AU - Iryu, Yasufumi
AU - Yamada, Tsutomu
AU - Shibasaki, Hiroshi
AU - Shiokawa, Satoshi
N1 - Funding Information:
We greatly appreciate Y. Kato of Hydrographic and Oceanographic Department, JCG (JHOD) for fruitful discussion on regional tectonics. We also thank D. J. W. Piper, P. Quilty, and an anonymous reviewer for useful and constructive comments on our manuscript. This study has been conducted as part of the project titled “Basic researches on exploration technologies for deep-sea natural resources” funded by METI (Ministry of Economy, Trade and Industry).
PY - 2008/1/10
Y1 - 2008/1/10
N2 - Carbonate rock cores drilled on the Kikai Seamount, northern Philippine Sea are examined for better understanding of tectonic history of the northern Philippine Sea. The Kikai Seamount, the summit of which is at 1960 m water depth, is an isolated high on the northwestern part of the Amami Plateau formed by subduction-related arc volcanism, and is situated close to the axis of the Ryukyu Trench in front of the Ryukyu Arc, SW Japan. The seamount is capped with shallow-water carbonates such as coral rudstone. Detailed examinations of lithology, larger foraminiferal assemblages, and Sr isotope composition reveal that the core material comprises Miocene carbonates unconformably overlain by Early Pleistocene carbonates. It indicates rapid subsidence of the Kikai Seamount since the Early Pleistocene. The most probable cause of rapid subsidence is collision and subduction of the Amami Plateau laden with the Kikai Seamount. The rapid subsidence may have started when the western corner of the plateau reached the Ryukyu Trench and began subduction beneath the Ryukyu Arc. The onset of the subsidence is likely to be controlled by a motion change in the Philippine Sea Plate. The latest change in subduction direction from north to northwestward into northwestward to west has been believed to have occurred at 1-2 Ma during latest Pliocene to Early Pleistocene time. The change of direction resulted in the shift from oblique into right-angle subduction of the plate beneath the Ryukyu Arc and also the onset of the collision and subduction of the Amami Plateau.
AB - Carbonate rock cores drilled on the Kikai Seamount, northern Philippine Sea are examined for better understanding of tectonic history of the northern Philippine Sea. The Kikai Seamount, the summit of which is at 1960 m water depth, is an isolated high on the northwestern part of the Amami Plateau formed by subduction-related arc volcanism, and is situated close to the axis of the Ryukyu Trench in front of the Ryukyu Arc, SW Japan. The seamount is capped with shallow-water carbonates such as coral rudstone. Detailed examinations of lithology, larger foraminiferal assemblages, and Sr isotope composition reveal that the core material comprises Miocene carbonates unconformably overlain by Early Pleistocene carbonates. It indicates rapid subsidence of the Kikai Seamount since the Early Pleistocene. The most probable cause of rapid subsidence is collision and subduction of the Amami Plateau laden with the Kikai Seamount. The rapid subsidence may have started when the western corner of the plateau reached the Ryukyu Trench and began subduction beneath the Ryukyu Arc. The onset of the subsidence is likely to be controlled by a motion change in the Philippine Sea Plate. The latest change in subduction direction from north to northwestward into northwestward to west has been believed to have occurred at 1-2 Ma during latest Pliocene to Early Pleistocene time. The change of direction resulted in the shift from oblique into right-angle subduction of the plate beneath the Ryukyu Arc and also the onset of the collision and subduction of the Amami Plateau.
KW - Amami Plateau
KW - Kikai Seamount
KW - Pleistocene
KW - northern Philippine Sea
KW - rapid subsidence
KW - shallow-water carbonates
KW - subduction
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U2 - 10.1016/j.margeo.2007.08.004
DO - 10.1016/j.margeo.2007.08.004
M3 - Article
AN - SCOPUS:37249054941
VL - 247
SP - 35
EP - 45
JO - Marine Geology
JF - Marine Geology
SN - 0025-3227
IS - 1-2
ER -