A subducting seamount beneath the Nankai Accretionary Prism off Shikoku, southwestern Japan

Park, Jin-Oh; Tsuru, Takeshi Go; Kaneda, Yasufumi; Kono, Yoshiteru; Kodaira, Shuichi; Takahashi, Narumi; Kinoshita, Hajimu

doi:10.1029/1999gl900134

Cited by 91 publications

(101 citation statements)

References 15 publications

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“…[59] Several authors have been discussed the mechanisms of seamount accretion and subduction with conclusions suggesting complete transfer of the intact mass to the upper plate [Cloos, 1992;Park et al, 1999], complete subduction [Yamazaki and Okamura, 1989;Kodaira et al, 2000;Husen et al, 2002;Soh and Tokuyama, 2002] or a combination of the two through the nucleation of thin-skinned duplexes [Ueda, 2005] or flank fracturing [Cloos and Shreve, 1996;Baba et al, 2001]. These different results have been explained by the varying amount of lubrication at the subduction thrust interface [Seno, 2006].…”

Section: From Tectonic Accretion To Tectonic Erosion: Discussionmentioning

confidence: 96%

From seamount accretion to tectonic erosion: Formation of Osa Mélange and the effects of Cocos Ridge subduction in southern Costa Rica

Vannucchi¹,

et al. 2006

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The Costa Rica portion of the Middle America Trench (MAT) is characterized by active tectonic erosion, a process that causes the removal of material from the base of the upper plate as the plate boundary migrates upward. Offshore studies demonstrate accelerated subduction erosion starting at the Miocene‐Pliocene boundary, as the result of subduction of thickened Galapagos related crust, as presently represented by the Cocos Ridge. The subduction of the Cocos Ridge also caused uplift and exposure of the outer forearc on the Osa Peninsula, which offers a window to explore the tectonic evolution of the area. The rocks outcropping on Osa Peninsula are a middle Eocene–middle Miocene mélange dominated by basalt, chert, and limestone resulting from accretion of seamounts. The accretion‐dominated period of the MAT evolution ended at the Miocene‐Pliocene boundary, when thickened crust, a paleo‐Cocos Ridge, produced at the Galapagos hot spot arrived at the trench. The thick crust caused uplift and severe tectonic erosion of the accretionary edifice allowing exhumation of the Osa Mélange. The change from accretion to erosion caused the outer forearc to be offset along subvertical faults that define small (kilometer to tens of kilometers size) blocks that are going through differential vertical movements in response to the morphology of the subducting ridge. Subduction accretion and erosion are two processes that can alternate in time and space or coexist along the same margin, so that mass removal can develop on a previously growing margin and completely remove an accretionary prism.

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Section: From Tectonic Accretion To Tectonic Erosion: Discussionmentioning

confidence: 96%

From seamount accretion to tectonic erosion: Formation of Osa Mélange and the effects of Cocos Ridge subduction in southern Costa Rica

Vannucchi¹,

et al. 2006

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“…This implies that the block is presumably not a seamount, such as bodies already discovered at the region off Cape Muroto (Park et al, 1999;Kodaira et al, 2000).…”

Section: Resultsmentioning

confidence: 99%

Buried large block revealed by gravity anomalies in the Tonankai and Nankai earthquakes regions, southwestern Japan

Honda

Kono

2005

Earth Planet Sp

Self Cite

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We confirmed existence of a buried large block beneath seafloor off Cape Shionomisaki, Kii Peninsula, southwestern Japan, by improving marine gravity data. We found that the 1944 Tonankai and 1946 Nankai earthquakes occurred close to this block. The block is characterized by high gravity anomalies of 80 mGal larger than surrounding area with a diameter of about 40 km. Center of the anomaly is located 30 km off Cape Shionomisaki, southern end of the Kii Peninsula. This high gravity anomaly can be explained by existence of a higher density body with approximate thickness of 8 km just beneath the seafloor. This block coincides with the reported high velocity zone from recent seismic refraction survey in this area. Judging from seismic velocity, density, and geologic evidences, the block presumably consists of intruded acidic rocks, not seamount.

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“…The lower part of the Shikoku Basin displays a complex geometry influenced by basement topography (Ike et al, 2008b). Basement highs are also imaged within the subduction zone (Kodaira et al, 2003;Dessa et al, 2004), where they influence margin structure (Lallemand et al, 1992;Le Pichon et al, 1996;Park et al, 1999;Mazzotti et al, 2002;Bangs et al, 2006;Moore et al, 2009) and seismicity (Kodaira et al, 2000a;Park et al, 2004). The NanTroSEIZE expeditions focused on the Kumano transect, while earlier Ocean Drilling Program (ODP) and Deep Sea Drilling Project (DSDP) sites were drilled on the Muroto transect and the Ashizuri transects, respectively, in the central and western part of Shikoku Basin ( Fig.…”

Section: Geologic Setting and Previous Workmentioning

confidence: 99%

Scientific Drilling

Henry

Kanamatsu

Moe

et al. 2012

Scientific Drilling

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A subducting seamount beneath the Nankai Accretionary Prism off Shikoku, southwestern Japan

Cited by 91 publications

References 15 publications

From seamount accretion to tectonic erosion: Formation of Osa Mélange and the effects of Cocos Ridge subduction in southern Costa Rica

From seamount accretion to tectonic erosion: Formation of Osa Mélange and the effects of Cocos Ridge subduction in southern Costa Rica

Buried large block revealed by gravity anomalies in the Tonankai and Nankai earthquakes regions, southwestern Japan

Scientific Drilling

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