Transition from frontal accretion to underplating in a part of the Nankai Trough Accretionary Complex off Shikoku (SW Japan) and extensional features on the lower trench slope

Leggett, Jeremy; Aoki, Yasuhiro; Toba, Takefumi

doi:10.1016/0264-8172(85)90003-0

Cited by 43 publications

(31 citation statements)

References 12 publications

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“…Trough-parallel normal faults are well developed within the Kumano basin immediately landward of the outer ridge [Park et al, 2002]. These normal faults may be related to dynamic activity on the mega-splay fault, tectonic evolution of the splay-fault and fore-arc basin [Gulick et al, 2010], or underplating [Leggett et al, 1985]. However, they are not found around Site C0009 and the stress state cannot be determined from seismic reflection profiles alone.…”

Section: Geologic Settingmentioning

confidence: 99%

In situ stress state from walkaround VSP anisotropy in the Kumano basin southeast of the Kii Peninsula, Japan

Tsuji

Hino

Yukitoshi

et al. 2011

Geochem. Geophys. Geosyst.

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To reveal the stress state within the Kumano basin, which overlies the Nankai accretionary prism, we estimated seismic anisotropy from walkaround vertical seismic profiling (VSP) data recorded at Site C0009 during Integrated Ocean Drilling Program (IODP) Expedition 319. We obtained the following anisotropic parameters: (1) P wave velocity anisotropy derived from azimuthal normal moveout (NMO) velocity analysis, (2) P wave amplitude variation with azimuth, and (3) axes of symmetry of S wave splitting. Azimuthal variations of P wave velocity by ellipsoidal fitting analysis showed that P wave velocity anisotropy within sediments of the Kumano basin was ∼5%. Both the directions of fast P wave velocity and strong amplitude are aligned with the convergence vector of the Philippine Sea plate. Furthermore, S wave splitting analysis indicated that S wave polarization axes were parallel to and normal to the direction of plate subduction. These results indicate that the maximum horizontal stress at Site C0009 in the Kumano basin is in the direction of plate subduction. The horizontal differential stress estimated from the P wave velocity anisotropy (2.7∼5.5 MPa) indicates that the maximum horizontal stress is similar in magnitude to (or a little higher than) the vertical stress.

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Section: Geologic Settingmentioning

confidence: 99%

In situ stress state from walkaround VSP anisotropy in the Kumano basin southeast of the Kii Peninsula, Japan

Tsuji

Hino

Yukitoshi

et al. 2011

Geochem. Geophys. Geosyst.

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“…The Tosabae Embayment is a large depression which has developed seaward of the Tosabae outer ridge ( Fig. 5a, Leggett et al 1985). The 4000 m contour line arches landward about 25 km.…”

Section: Bathymetry Of the Nankai Troughmentioning

confidence: 97%

Geomorphological study on a clastic accretionary prism: The Nankai Trough

Okino¹,

Kato²

1995

Island Arc

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The Nankai Trough, off southwest Japan, is one of the best sites for the study of geomorphic characteristics of a elastic accretionary prism. A recent multibeam survey over the central and eastern parts of the Nankai accretionary prism has revealed a large variation of the topography along the trough axis. Analysis of the bathymetric data suggests the existence of prism deformational features of different scales, such as depressions, embayment structures and cusps. These structures are the results of slope instability caused by basement relief of subducted oceanic plate. Unstable slopes recover by new accretion and development of a low angle thrust. Small-scale deformation due to the subduction of a small isolated seamount is then adjusted to the regional trend. By contrast, a 30 km indentation of the wedge observed in the eastern part of the Nankai Trough, the Tenryu Cusp, has seemed to retain its geometry. The subducted Philippine Sea plate has deformed greatly near the eastern end of the Nankai Trough, because of the collision between the Izu-Ogasawara (Bonin) arc and central Japan. Therefore, the indentation may be the result of the continuous subduction of a basement high, such as the Zenisu Ridge, which has been formed under north-south compression due to the arc-arc collision.

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“…The model of formation of the Torlesse Complex currently favoured by many workers is that it represents an ancient accretionary wedge. At a convergent, continental margin plate boundary, seafloor material and trench-fill sediments are scraped off, undergo decoupling from the subducting plate, and are accreted into an accretionary wedge at the inner trench wall (frontal accretion, Leggett et al 1985;Mascle et al 1986). Accretion of progressively younger packets of sediments is typical of presently active subduction systems (e.g., Karig & Sharman 1975;Scholl et al 1980;von Huene 1984;Brown & Westbrook 1987;Moore & Shipley 1988).…”

Section: Summary and Discussionmentioning

confidence: 99%

Structure of melange and associated units in the Torlesse accretionary wedge, Tararua Range, New Zealand

Orr¹,

Korsch

Foley³

1991

New Zealand Journal of Geology and Geophysics

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Deformation of the Late Jurassic -Early Cretaceous Torlesse Complex in the southeastern Tararua Range is characterised by development of melange, several generations of folds, faults at both a low angle and high angle to bedding, shear foliation, and cleavage. The region has undergone the following deformational sequence: (1) Development of at least two fold generations; (2) Fragmentation and disruption by faulting. Faults at a low angle and high angle to bedding have disrupted the sequence, in places producing chaotically disrupted units (melange). The Tauherinikau Melange represents a probable along-strike northern continuation of the Esk Head Melange from the South Island; (3) Post-melange folding; (4) Holocene faulting. Overall, the deformation is consistent with accretion at a convergent plate margin, followed by the present strike-slip dominant regime.

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Transition from frontal accretion to underplating in a part of the Nankai Trough Accretionary Complex off Shikoku (SW Japan) and extensional features on the lower trench slope

Cited by 43 publications

References 12 publications

In situ stress state from walkaround VSP anisotropy in the Kumano basin southeast of the Kii Peninsula, Japan

In situ stress state from walkaround VSP anisotropy in the Kumano basin southeast of the Kii Peninsula, Japan

Geomorphological study on a clastic accretionary prism: The Nankai Trough

Structure of melange and associated units in the Torlesse accretionary wedge, Tararua Range, New Zealand

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