Mass Wasting on Continental Margins

Coleman, J.M.; Prior, David B.

doi:10.1146/annurev.ea.16.050188.000533

Cited by 100 publications

(39 citation statements)

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“…Spontaneous delta collapses resulting from a buildup of excess pore pressure due to rapid sediment loading and lake-level drops in combination with oversteepening as a result of increased sediment charging on the frontal delta slopes (Sultan et al 2004;Girardclos et al 2007) are likely one of the main causes for gravitational mass flows and turbidite deposition. When considering the specific setting of Lake Towuti, additional factors increasing stresses and/or lower sediment strength, such as earthquakes, high-volume river discharge events, storm waves, biogenic pore gas charging, seasonal lake-level fluctuations, as well as complex interactions of these factors may also contribute to Mahalona Delta slope failure (Coleman and Prior 1988;Hampton et al 1996).…”

Section: Discussionmentioning

confidence: 99%

Depositional modes and lake-level variability at Lake Towuti, Indonesia, during the past ~29 kyr BP

et al. 2015

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Lake Towuti (2.5°S, 121.5°E) is a longlived, tectonic lake located on the Island of Sulawesi, Indonesia, and in the center of the Indo-Pacific warm pool (IPWP). Lake Towuti is connected with upstream lakes Matano and Mahalona through the Mahalona River, which constitutes the largest inlet to the lake. The Mahalona River Delta is prograding into Lake Towuti's deep northern basin thus exerting significant control on depositional processes in the basin. We combine high-resolution seismic reflection and sedimentological datasets from a 19.8-m-long sediment piston core from the distal edge of this delta to characterize fluctuations in deltaic sedimentation during the past *29 kyr BP and their relation to climatic change. Our datasets reveal that, in the present, sedimentation is strongly influenced by deposition of laterally transported sediments sourced from the Mahalona River Delta. Variations in the amount of laterally transported sediments, as expressed by coarse fraction amounts in pelagic muds and turbidite recurrence rates and cumulative thicknesses, are primarily a function of lake-level induced delta slope instability and delta progradation into the basin. We infer lowest lake-levels between *29 and 16, a gradual lake level rise between *16 and 11, and high lake-levels between *11 and 0 kyr BP. Periods of highest turbidite deposition, *26 to 24 and *18 to Electronic supplementary material The online version of this article (16 kyr BP coincide with Heinrich events 2 and 1, respectively. Our lake-level reconstruction therefore supports previous observations based on geochemical hydroclimate proxies of a very dry last glacial and a wet Holocene in the region, and provides new evidence of millennial-scale variations in moisture balance in the IPWP.

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Section: Discussionmentioning

confidence: 99%

Depositional modes and lake-level variability at Lake Towuti, Indonesia, during the past ~29 kyr BP

et al. 2015

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“…In addition to these processes, it can be inferred that slow creep and dilute suspensions of sand, silt, and claysized particles also make minor contributions to the downslope transport of detritus. Neither debris flows nor locally-derived turbidity currents are thought to occur; thick accumulations of fine-grained sediments generally required to initiate these processes are absent (e.g., Coleman and Prior, 1988).…”

Section: Geomorphology and Mass Wasting Processesmentioning

confidence: 99%

A submersible study in the western Blanco fracture Zone, N.E. Pacific: Structure and evolution during the last 1.6 Ma

et al. 1995

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Abstract.During July and August 1991, the French-American Blanconaute dive program used the French submersible Nautile to investigate the West Blanco Depression (WBD), a deep, elongate trough located at the intersection of the Blanco Transform Fault Zone with the southern Juan de Fuca Ridge (JdFR). Twenty dives were carried out along the north wall of the WBD, which exposes the upper oceanic crust over a 65 km distance, from the JdFR axis (to the west) to the oblique trace of an ancient propagator (to the east, crustal age around 2 Ma). Thirteen of these dives were precisely located within a 13 x 7 km zone of the north wall, covered by a high-resolution sonar mapping operation during the Blancotrough cruise in 1987. This series of geological traverses, plus 4 dives across the south wall of the WBD (one dive) and the adjacent Parks Plateau (3 dives), collected 242 rock samples. We report here the main results of the dive program and preliminary laboratory studies:l. Transform-related tectonic activity has recently abandoned the southern margin of Parks Plateau, and is presently located inside the WBD area, mainly along its northern wall. The tectonic features observed are compatible with a right-lateral strike-slip system, with a NE-SW extensional component.2. Three main lithological units are exposed along the north wall of the WBD. From top to bottom, they are: (1) a Volcanic Unit, forming a steep upper cliff, made of massive and pillow flows and basaltic dikes, with an estimated average thickness of 800 m; (2) a less steep Transition Zone, about 150 to 400 In thick, largely masked by rubble but exposing both diabase outcrops and pillow flows; and (3) a massive Diabase Unit, exposed over 700-800 m, with a dike complex structure visible from place to place, and cut by a net of hydrothermal veins. Deep crustal rocks such as gabbros were not observed.3. Spectacular mass-wasting features are visible all along the north wail of the WBD. About 60% of the face of the wall is masked by talus cones, rubble, rock avalanche deposits and slide blocks. Three main landslides, of approximately one km 3 in volume each, were tentatively identified. One of them was mapped in detail and consists of an approximately 300 m thick (0.85 km3), coherent slide block

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“…Slope instabilities can thus be the result of stress increases, sediment strength reduction, or a combination of both (Coleman and Prior, 1988;Lee et al, 1991). The two major factors generally invoked as responsible for slope instabilities are: -A downslope stress increase, by external load or by basal unload.…”

Section: Factors Responsible For Submarine Slope Instabilitiesmentioning

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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Mass Wasting on Continental Margins

Cited by 100 publications

References 0 publications

Depositional modes and lake-level variability at Lake Towuti, Indonesia, during the past ~29 kyr BP

Depositional modes and lake-level variability at Lake Towuti, Indonesia, during the past ~29 kyr BP

A submersible study in the western Blanco fracture Zone, N.E. Pacific: Structure and evolution during the last 1.6 Ma

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

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