The eastern and western ends of Nankai Trough: results of Box 5 and Box 7 Kaiko survey

Pichon, Xavier Le; Iiyama, T.; Chamley, Hervé; Charvet, Jacques; Faure, Michel; Fujimoto, Hiromi; Furuta, Toshio; Ida, Yoshiaki; Kagami, Hideo; Lallemant, S.; Leggett, Jeremy; Murata, Akinobu; Okada, Hakuyu; Rangin, Claude; Renard, Vincent; Taira, Asahiko; Tokuyama, Hidekazu

doi:10.1016/0012-821x(87)90066-5

Cited by 75 publications

(42 citation statements)

References 12 publications

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“…1). Fan-like sediment accumulations at the mouths of Tenryu and Shiono-misaki canyons attest to local transverse input into the trench (Le Pichon et al, 1987b;Shimamura, 1989). With the exception of Ashizuri Canyon (which is located downgradient), all of these physiographic features could provide sediment to the central trench floor in the vicinity of Site 808.…”

Section: Inferred Dispersal Directionsmentioning

confidence: 99%

“…Several bathymetric features need to be considered in the Nankai Trough region. The northeast end of the trench is connected directly to a major sediment conduit, Suruga Trough (Le Pichon et al, 1987b;Nakamura et al, 1987). This canyon system begins near the shoreline with many small channels and slope gullies associated with the Fuji River fan-delta ( Fig.…”

Section: Inferred Dispersal Directionsmentioning

confidence: 99%

“…Second, whereas previous DSDP drill sites were located farther down the axial gradient and closer to the western edge of the trench, Site 808 was drilled near the center of the basin (Fig. 1), along the trend of an extinct spreading center that was responsible for the formation of oceanic crust within Shikoku Basin (Chamot-Rooke et al, 1987;Le Pichon et al, 1987a). Even though the basement relief has been buried within the trench, the proximity to the inherited bathymetric high clearly affected rates of sedimentation outboard of the trench (Pickering et al, this volume).…”

Section: Introductionmentioning

confidence: 99%

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Provenance and Dispersal Patterns of Sediments in the Turbidite Wedge of Nankai Trough

Underwood¹,

Orr²,

Pickering³

et al. 1993

Proceedings of the Ocean Drilling Program, 131 Scientific Results

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Drill core recovered at Ocean Drilling Program Site 808 (Leg 131) proves that the wedge of trench sediment within the central region of the Nankai Trough comprises approximately 600 m of hemipelagic mud, sandy turbidites, and silty turbidites. The stratigraphic succession thickens and coarsens upward, with hemipelagic muds and volcanic-ash layers of the Shikoku Basin overlain by silty and sandy trench-wedge deposits. Past investigations of clay mineralogy and sand petrography within this region have led to the hypothesis that most of the detritus in the Nankai Trough was derived from the Izu-Honshu collision zone and transported southwestward via axial turbidity currents. Shipboard analyses of paleocurrent indicators, on the other hand, show that most of the ripple cross-laminae within silty turbidites of the outer marginal trench-wedge facies are inclined to the north and northwest; thus, many of the turbidity currents reflected off the seaward slope of the trench rather than moving straight down the trench axis. Shore-based analyses of detrital clay minerals demonstrate that the hemipelagic muds and matrix materials within sandy and silty turbidites are all enriched in illite; chlorite is the second-most abundant clay mineral, followed by smectite. In general, the relative mineral percentages change relatively little as a function of depth, and the hemipelagic clay-mineral population is virtually identical to the turbidite-matrix population.Comparisons between different size fractions (<2 µm and 2-6 µm) show modest amounts of mineral partitioning, with chlorite content increasing in the coarser fraction and smectite increasing in the finer fraction. Values of illite crystallinity index are consistent with conditions of advanced anchimetamoΦhism and epimetamoΦhism within the source region. Of the three mica poly types detected, the 2Mj variety dominates over the IM and IMd polytypes; these data are consistent with values of illite crystallinity. Measurements of mica b o lattice spacing show that the detrital illite particles were eroded from a zone of intermediate-pressure metamoΦhism. Collectively, these data provide an excellent match with the lithologic and metamoΦhic character of the Izu-Honshu collision zone. Data from Leg 131, therefore, confirm the earlier inteΦ r etations of detrital provenance. The regional pattern of sediment dispersal is dominated by a combination of southwest-directed axial turbidity currents, radial expansion of the axial flows, oblique movement of suspended clouds onto and beyond the seaward slope of the Nankai Trough, and flow reflection back toward the trench axis.

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Section: Inferred Dispersal Directionsmentioning

confidence: 99%

Section: Inferred Dispersal Directionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Provenance and Dispersal Patterns of Sediments in the Turbidite Wedge of Nankai Trough

Underwood¹,

Orr²,

Pickering³

et al. 1993

Proceedings of the Ocean Drilling Program, 131 Scientific Results

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“…The upper Shikoku Basin facies off the Kumano Basin pinches out toward the north, whereas the lower succession has a more complicated geometry resulting from basement topographic influence (Le Pichon et al, 1987a, 1987bMazzotti et al, 2000;Moore, Taira, Klaus, et al, 2001): seismic thickness decreases above large basement highs, and acoustically transparent units indicate local absence of the sand packages that characterize most other parts of the lower Shikoku Basin. The mechanical differences between subducting basement highs and plains could be significant for fault zone dynamics and earthquake rupture behavior.…”

Section: Geological Settingmentioning

confidence: 99%

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2010

IODP Scientific Prospectus

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“…Deformation of the northern Izu-Bonin arc is focused on the leading edge of the downgoing plate where subduction-related thrusting at the Nankai Trough is stepping seaward to the south side of Zenisu Ridge, the northernmost volcanic cross-chain of the arc (Le Pichon et al, 1987). Terranes of Izu-Bonin arc crust have been accreted onto southern Honshu during the last 15 m.y.…”

Section: Leg 126mentioning

confidence: 99%

Bonin Arc-Trench System

Fujioka¹,

Taylor²,

Janecek³

1989

ODP Preliminary Report

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Leg 126Preliminary Report page 7 ABSTRACTThe Izu-Bonin intra-oceanic island arc is a product of the sübduction of Pacific lithosphere since the Eocene. The focus of Ocean Drilling Program (ODP) Leg 126 was to study three important and poorly understood aspects of this system, namely (1) the origin and evolution of the forearc, investigated by drilling a series of holes through the sediments and into the basement of the forearc basin (Sites 787 and 792-793); (2) the process and products of arc rifting, investigated by drilling holes into the center (Sites 790/791) and eastern footwall (Sites 788/789) of the Sumisu backarc rift; and (3) recycling of subducted lithosphere and evolution of the mantle, investigated indirectly from the composition of the volcanic rocks recovered from all sites.The principal drilling results of Leg 126 show that the forearc basin formed between 31 and 34 Ma by separation of the formerly contiguous frontal and outer arc highs. Igneous basement beneath the center of the forearc basin includes high-Mg series andesites, andesites with boninitic affinities, and low-Mg series lavas with tholeiitic affinities. Following a minimum of volcanic output between 24 and 13 Ma, there has been a steady increase in explosive volcanic activity in the forearc with a dramatic increase in the late Quaternary. Paleomagnetic evidence shows that the forearc has been translated about 15°N since 30 Ma. Benthic foraminifer^ data suggest 1-2 km of basement uplift has occurred since the middle Oligocene. Pore waters in the Oligocene volcanogenic sediments of the forearc basin are the most extensively altered pore water of sea-water origin ever sampled by DSDP/ODP. Low-temperature alteration of the volcanogenic sediments has produced fluids extremely enriched in calcium and depleted in magnesium, silica, and sulfate.The present stage of rifting in the Sumisu Rift at 31°N began between 3.56 and 1.1 Ma with both present-day and pre-rift volcanism along the volcanic front dominated by rhyolitic pumice eruptions. The footwall of the Sumisu Rift has been uplifted 200-1700 m, and rift basement depth prior to 1.1 Ma exceeded 2 km. The basement of the rift is formed by early rift basaltic lavas and intrusives, as well as by arc pyroclastics metamorphosed to zeolite or lower greenschist facies. Intra-rift basaltic eruptions and rhyolitic eruptions were common but explosive arc volcanic activity dramatically increased 250 Ka. Unlike the forearc region, fluids other than sea water are not circulating locally through the sediments in the Sumisu Rift. TECTONIC SETTING AND EVOLUTION OF THE IZU-BONIN-MARIANA REGIONThe present-day tectonic configuration of the Izu-Bonin-Mariana region ( Fig. 1) comprises, from east to west: the trench; the forearc terrane, made up of an inner trench wall, an outer-arc high, a forearc basin, and a frontal-arc high; the active Izu-Bonin and Mariana island arcs; the Izu-Bonin backarc rifts and the actively spreading Mariana backarc basin and its remnant arc, the West Mariana Ridge; the Shikoku and Pa...

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The eastern and western ends of Nankai Trough: results of Box 5 and Box 7 Kaiko survey

Cited by 75 publications

References 12 publications

Provenance and Dispersal Patterns of Sediments in the Turbidite Wedge of Nankai Trough

Provenance and Dispersal Patterns of Sediments in the Turbidite Wedge of Nankai Trough

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Bonin Arc-Trench System

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