Submarine debris flow deposits detected by long-range side-scan sonar 1,000-kilometers from source

Simm, Robert W.; Kidd, Robert B.

doi:10.1007/bf02463436

Cited by 42 publications

(11 citation statements)

References 12 publications

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“…The structureless internal character has been attributed to the scattering of incident sound energy by chaotic bedding and flow structures, while impedance contrasts at the top and bottom of the flows return distinct echoes or reflections (Simm & Kidd 1984). In unconsolidated sediments even a short displacement will be enough to disrupt the continuity of internal reflectors (Embley 1980).…”

Section: Discussionmentioning

confidence: 99%

“…Where lobes coalesce, the resulting overlapping or amalgamated sequence may total a thickness of 50-60 m (Prior & Coleman 1984). On the continental margins off NW Africa (Embley 1976;Jacobi 1976;Simm & Kidd 1984;Kidd et al 1987), eastern N America (Embley 1980), Israel (Almagor & Wiseman 1982), S Korea (Chough 1984) and California (Thornton 1984) debris flows extend down the slope into deep water rise and abyssal plain settings, and range from 1 -6 0 m thick and from several kilometres to several hundred kilometres in length.…”

Section: Discussionmentioning

confidence: 99%

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Glacially-influenced sedimentation on the Hebridean slope, northwestern United Kingdom continental margin

Stoker

1990

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Pleistocene sediments on the northern Hebrides Slope form a localized, mounded slope-front deposit up to 200 m thick of limited downslope and alongslope extent. In seismic profiles, this slope-front deposit is characterized by a prograding, oblique-parallel reflection configuration. The bulk of the succession is characterized by three distinct depositional packages, each comprising an amalgamated sequence of mass flow deposits consisting primarily of debris flow diamicts with turbidite sands and muds. They represent re-sedimented glacimarine deposits. The mass flow packages are bounded by discrete, slope-wide, moderate-to high-amplitude reflectors. These reflections may be due to different degrees of consolidation of the sediments and/or the presence of thin, interbedded units of glacimarine dropstone mud. They indicate periods of reduced sediment supply to the slope. The slope facies interdigitate with a submarine end-moraine at the shelf-edge, and deposition probably occurred during a single glacial cycle. The restricted occurrence of the debris flows is thus attributed to a local source reflecting the shelf-edge position of an ice-sheet in this area at the time of sedimentation. Fluctuations in the sedimentation rate, independent of major climatic variation, suggest that the ice-sheet may have experienced alternate periods of basal melting and freezing. Ice-marginal processes have contributed significantly to the construction of the slope apron on the northern Hebrides Slope. During this period of sedimentation, the shelf-edge has prograded seaward, to the NW, by up to 5 km.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Glacially-influenced sedimentation on the Hebridean slope, northwestern United Kingdom continental margin

Stoker

1990

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“…Slide scars show erosion to a depth of 80 m and the total area affected was 18000km 2 • Masson et al Cl992b) showed that part of the area mapped by Embley and later workers (e.g. Simm and Kidd 1984;Kidd et al 1985Kidd et al , 1987 as the Saharan Slide in fact belonged to another !arge slide which they termed the Canary Debris Flow. This debris flow is associated with an eroded area of 6000 km 2 on the lower slopes of the westernmost Canary Islands of La Palma and Hierro.…”

Section: Debris Flows On the Continental Marginmentioning

confidence: 97%

Sediment mass wasting in the Canary Basin

Weaver

Masson

Gunn

et al. 1995

Atlas of Deep Water Environments

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“…A large leveed channel appears to be the principal feature within the system . Simm & Kidd (1984) suggested that the debrite identified in the study area is related to the 'Saharan Sediment Slide', which has been described by Embley (1975Embley ( , 1976Embley ( , 1980Embley ( , 1982. On the abyssal plain to the west, channels and debrites are absent, and the basin floor is largely featureless, except for prominent seamounts protruding through the sediment cover and bioturbation structures at the sediment surface .…”

Section: Geological Settingmentioning

confidence: 66%

Late Quaternary mass movement on the lower continental rise and abyssal plain off Western Sahara

Simm¹,

Weaver

Kidd

et al. 1991

Sedimentology

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The late Quaternary development of part of the lower continental rise off Western Sahara has been determined from an investigation of short (< 2 m) gravity cores collected from a deep‐sea channel, the interchannel areas and an abyssal hill, between 30 and 33°N. Stratigraphic analysis is based on systematic variations in abundances of particular coccolith species and pelagic sediment types, referenced to the oxygen isotope time‐scale. During the last 73 000 years deposition in the channel has included volcaniclastic sand/silt turbidites and minor marl turbidites as well as pelagic sediments. The interchannel area has fewer turbidites, and the sands present were probably deposited from turbidity currents which spilt over the channel sides. The last‘event’ to give rise to sands in the channel and interchannel area occurred about 45 000 years ago. Although the channel has been inactive as an area of turbidity current deposition for the last 20 000 years, sands were deposited elsewhere on the lower rise, indicating that turbidity current transport routes have varied in time. Turbidity current deposition on the abyssal plain and low‐lying continental rise appears to be related to distinct sliding events involving transport of material from various sources. Thin marl turbidites are interbedded with pelagic sediments in the area of sediment drape. There is a strong correlation between these and the thick marl turbidites on the abyssal plain, suggesting that the same turbidity current‘events’, occurring about once every 25 000 years, gave rise to both sets of deposits. The thinner units probably represent deposition from the outer parts or tails of the large turbidity flows. The turbidites occur at glacial/interglacial transitions, suggesting that the slides that created them were triggered by mechanisms related to climatic change. Several volcaniclastic sand/silt units within the channel and in interchannel areas occupy mid‐stage stratigraphic positions, perhaps indicating a different triggering mechanism for slides around volcanic islands. A debris flow deposit (debrite), between 30°N, 21°W and 31°N, 24°W, is related to the Saharan Sediment Slide, a major mass movement feature on the continental slope over 1000 km to the southeast. Stratigraphic correlations indicate that this slide produced a large turbidity current as well as a debris flow.

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Submarine debris flow deposits detected by long-range side-scan sonar 1,000-kilometers from source

Cited by 42 publications

References 12 publications

Glacially-influenced sedimentation on the Hebridean slope, northwestern United Kingdom continental margin

Glacially-influenced sedimentation on the Hebridean slope, northwestern United Kingdom continental margin

Sediment mass wasting in the Canary Basin

Late Quaternary mass movement on the lower continental rise and abyssal plain off Western Sahara

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