Turbidites of the Hatteras and Sohm abyssal plains, western North Atlantic
1971; Elsevier BV; Volume: 11; Issue: 5 Linguagem: Inglês
10.1016/0025-3227(71)90034-x
ISSN1872-6151
AutoresD. R. Horn, Michael T. Ewing, Barbara Horn, M. N. Delach,
Tópico(s)Aeolian processes and effects
ResumoThe distribution, thickness and textural properties of turbidites off the east coast of the United States are defined and discussed. Results of 195 granulometric analyses of turbidite layers are presented. Properties of deep-sea sands within a single basin are functions of availability of sediment and physiographic setting. In the Hatteras Abyssal Plain turbidity-current activity has been at a moderate level, there are no obstructions to flow, and sediment patterns are well-defined. Increasing distance from main route of flow (laterally and downcurrent) is matched by decrease in mean grain size, maximum particle size, range and thickness of units. Muddy sands are restricted to areas off the ends of submarine canyons and along principal avenues across the plain. The situation of the Sohm Abyssal Plain is different in that there has been an ample supply of sediment, more vigorous turbidity-current activity, seaward flow has been obstructed by many seamounts and seaknolls, and the overall result is a haphazard dispersal of sand by bottom-seeking flows. Many of the sands are muddy, poorly sorted and lack obvious grading. They have the textural properties of wackes. It is speculated that these abyssal plains represent modern sedimentary basins filled with flysch. If the results are combined with similar findings from other areas (Horn et al., 1971a, b), the major conclusion is that deep-sea sands and silts of the outer continental rise and adjacent abyssal plains have many properties of flysch and are emplaced by turbidity currents. These results corroborate the ideas of Kuenen (e.g., 1967). Inspection of the cores reveals nothing to support the concept that the sands are products of normal bottom-current activity.
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