Nankai Trough and Zenisu Ridge: a deep-sea submersible survey

Pichon, Xavier Le; Iiyama, T.; Boulègue, Jacques; Charvet, Jacques; Faure, Michel; Kano, Ken‐ichi; Lallemant, S.; Okada, Hakuyu; Rangin, Claude; Taira, Asahiko; Urabe, Tetsuro; Uyeda, Seiya

doi:10.1016/0012-821x(87)90072-0

Cited by 117 publications

(29 citation statements)

References 11 publications

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“…and tubeworms in the amphitheatre region indicates the active expulsion of sulphide-and methane-rich pore fluids from the sediment (Paull et al, 1984;Hecker, 1985;Suess et al, 1985;Kulm et al, 1986;Paull and Newman, 1987;Le Pichon et al, 1987). The spatial variation and style of the faunas provides evidence on the mechanisms controlling fluid expulsion, the chemical composition of the fluid, and the levels of fluid flow (Orange et al, 1999).…”

Section: Significance Of the Seeps And Chemosynthetic Communitiesmentioning

confidence: 99%

The Sissano, Papua New Guinea tsunami of July 1998 — offshore evidence on the source mechanism

Watts²,

et al. 2001

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The source of the local tsunami of 17 th July 1998 that struck the north shore of Papua New Guinea remains controversial, and has been postulated as due either to seabed dislocation (fault) or sediment slump. Alternative source mechanisms of the tsunami were addressed by offshore investigation using. multibeam bathymetry, sub-bottom profiling, sediment sampling and observation from the JAMSTEC Dolphin 3K Remotely Operated Vehicle and Shinkai 2000 Manned Submersible. The area offshore of Sissano is a complex active convergent margin with subduction taking place along the New Guinea Trench. Dominant transpressional convergence results in diachronous collision of the highstanding North Bismarck Sea Plate in a westerly direction. The result is a morphological variation along the Inner Trench Slope, with the boundary between eastern and western segments located offshore Sissano in an area of on-and offshore subsidence. This subsidence, together with nearshore bathymetric focusing, is considered to increase the tsunamigenic potential of the Sissano area. The offshore data allow discrimination between tsunami generating mechanisms with the most probable source mechanism of the local tsunami as a sediment slump located offshore of Sissano Lagoon. The approximately 5-10 km 3 slump is located in an arcuate, amphitheatreshaped structure in cohesive sediments that failed through rotational faulting. In the area of the amphitheatre there is evidence of recent seabed movement in the form of fissures, brecciated angular sediment blocks, vertical slopes, talus deposits and active fluid expulsion that maintains a chemosynthetic vent fauna. Dating of the slump event may be approximated 2 by the age of the chemosynthetic faunas as well as by a seismic signal from the failing sediment mass. Faults in the area offshore Sissano are mainly dip-slip to the north with recent movement only along planes of limited lateral extent. A possible thrust fault is of limited extent and with minimal (cm) reverse movement. Further numerical modeling of the tsunami also supports the slump as source over fault displacements.

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Section: Significance Of the Seeps And Chemosynthetic Communitiesmentioning

confidence: 99%

The Sissano, Papua New Guinea tsunami of July 1998 — offshore evidence on the source mechanism

Watts²,

et al. 2001

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“…The presence of chemoautotrophic benthic biological communities is commonly interpreted as a tracer of active fluid flow out of the seabed (Suess et al, 1985;Le Pichon et al, 1987;Boulegue et al, 1987;Moore and Vrolijk, 1992). Since the first in situ observation of biological communities related to cold seeps on the Oregon accretionary margin (Suess et al, 1985), similar observations have been reported from active erosional margins (Cadet et al, 1987;Sibuet et al, 1988) as well as from active accretionary margins (Le Pichon et al, 1987, 1990. Two main types of communities have been defined on the basis of the size and density of the bivalves (01~ et al, 1994a).…”

Section: Dating Of Rock Samplesmentioning

confidence: 99%

Slope instabilities at an active continental margin: large-scale polyphase submarine slides along the northern Peruvian margin, between 5 °S and 6 °S

et al. 1995

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A mega-submarine slide was evidenced along the Peruvian margin during a Seabeam survey of the R/V Charcot (Bourgois et al., 1986). The debris-slide was initially interpreted as the result of the slope failure occurring along a seaward curved scarp, and extending from east to west, along the line of maximum slope. Complementary bathymetric data obtained from the R/V Sonne survey conducted to the north and to the south of the previous surveyed area has resulted in the identification of large-scale polyphase submarine slides involving a total surface of about 1000 km', between latitudes 5"lSS and 6"05'S. Using Seabeam and Hydrosweep multibeam echosounder data in combination with deep-sea submersible observations, three distinct slope-failure types related to three main stages have been revealed. The three sliding phases occurred roughly along the same trend, orientated N230", and are therefore mainly controlled by the N80" orientation of the subducting Nazca plate.( 1) The first phase of slope failure is documented by a debris-avalanche deposit, which extends from the lower slope down to 5 km within the trench floor. The deposit originates from the northern wall of a wide valley located along the upper slope. (2) The second phase of slope failure is characterized by a debris-avalanche, with a crescent-shaped scar, located along the middle slope and a hummocky deposit covering the lower slope and extending up to 10 km across the trench. The volume of rock involved in this event is estimated to some 250 km3. The slope failure is assumed to be related to an oversteepening of the middle slope induced by a rollover deformation. (3) The third phase of slope failure corresponds to a translational sliding block and a toppling block with volumes of 6 km3 and 13 km3, respectively. The seismic energy produced during the seismic cycle has greatly increased fracturation and fluids buildup along the area previously weakened by a rollover fold. A restricted N-S folding is observed in the vicinity of the trench, to the north of the two debris-avalanche deposits. It may have formed in relation to the local compression limited to the subduction of the Nazca plate. Sliding and folding thus document the paradox between the compressive regime in the lower plate and the extensional regime in the upper part of the upper plate. IntroductionMost of the large-scale submarine landslides recognised worldwide occur either along intraplate volcanic alignments or along active continental margins. They include landslides along the steep submerged volcanic slopes of the Hawaiian islands (Lipman et al., 1988;Moore et al., 1989), the large landslides from Tristan da Cunha (South Atlantic island) and from El Hierro (Canary islands) described by Holcomb and Searle (1991), the volcanic debris-avalanche along the submerged flank of the Fournaise volcano off the Reunion island (L&at et al., 1989;Cochonat et al., 1990), the giant submarine slide on the northern slope of Puerto Rico island and the giant submarine slump along the northern Chile co...

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“…Indirect evidence for active expulsion of fluids at convergent margins has been suggested by the discovery of biological communities [Suess et aL, 1985;Le Pichon et al, 1987] and diagenetic carbonate deposits at discrete vent sites [Ritger et al, 1987]. These sites are characterized by numerous clams (Ca/yptogena sp.…”

mentioning

confidence: 99%

Fluid flow and mass flux determinations at vent sites on the Cascadia Margin Accretionary Prism

Carson¹,

Suess²,

Strasser³

1990

J. Geophys. Res.

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fluid venting from the toe of the accretionary prism off Oregon was measured in situ during a series of dives with DSRV Alvin in 1987 and 1988. A benthic chamber was placed over active vent sites to sequentially collect samples of venting fluids and to make direct measurements of discharge rates. Calibrated flow meter measurements and flow rates detennined from dissolved methane transfer indicate that discharge from two vent sites, Alvin 1428 and Alvin 1900, ranges roughly between 100 and 500 L m·2 d-1 . with the most reliable estimates falling in the range of 125·150 L m·2d-1. These rates imply subsurface advective flow oo the order of 100m yrl. Comparison of observed discharge rates with rates calculated for steady state expulsion supported by accretion·related compaction indicates that the observed flow is greater than predicted flow by several orders of magnitude. The disparity dictates that fluids are not derived locally, but are transported laterally within the prism, or that flow is not steady state and that individual vents are short-lived features in the ongoing accretion process.

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Nankai Trough and Zenisu Ridge: a deep-sea submersible survey

Cited by 117 publications

References 11 publications

The Sissano, Papua New Guinea tsunami of July 1998 — offshore evidence on the source mechanism

The Sissano, Papua New Guinea tsunami of July 1998 — offshore evidence on the source mechanism

Slope instabilities at an active continental margin: large-scale polyphase submarine slides along the northern Peruvian margin, between 5 °S and 6 °S

Fluid flow and mass flux determinations at vent sites on the Cascadia Margin Accretionary Prism

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