A study of 22 cores confirms that certain bulk and textural properties of deep‐sea sediments have a definite bearing on the transmission speed of sound through marine deposits. The higher the porosity, moisture content, and void ratio, the lower is the sound velocity. Increases in wet density are matched by increases in transmission speeds. There is no apparent correlation between sound velocity and either dry density or carbonate content. Shear strength is not a reliable index of transmission speed. Sound velocity is strongly related to grain size. Turbidites have high velocities, ash layers have intermediate velocities, and deep‐sea muds and clays have low velocities. There is a relation between transmission speed and sorting, skewness, and transformed kurtosis, but these size measures are dependent upon mean grain size. Grain size governs the bulk and textural properties of unconsolidated marine sediments and is the most important physical property in determining the acoustical nature of deep‐sea cores.
Horn, D. R., Ewing, J. I. and Ewing, M., 1972. Graded-bed sequences emplaced by turbidity currents north of 20"N in the Pacific, Atlantic and Mediterranean. Sedimentology, 18 :247-275.All core evidence supports the conclusion that abyssal plains are sites of graded-bed sequences deposited from turbidity flows. The deposits appear to be present-day equivalents of thin-to mediumbedded, graded, flysch-type sands and silts of many ancient geosynclines and sedimentary basins.' Larnont-Doherty Geological Observatory Contribution No. 1782.
A survey of 250 long piston cores from the North Pacific Ocean reveals that cores taken within definite areas of the sea floor have common sediment characteristics. These belong to distinct regions and are named sedimentary provinces. Three orders of sedimentary provinces occur in the North Pacific Basin. First order provinces follow the general form of the basin and are of great areal extent. They are sites of pelagic deposition and are named the Central North Pacific, Japan-Kuril, and Aleutian-Alaskan Provinces. Because the North Pacific Basin is protected from large-scale basinward transfer of terrigenous sediment, the limits of first order provinces match the boundaries of major water masses. Second order provinces are dominated by features of positive submarine relief, are restricted in size, and their boundaries follow the configuration of hills and ridges. They include the Hawaiian Ridge, Marcus-Necker Ridge, Shatsky Rise, Emperor Seamount Chain, and Ridge and Trough Provinces. Sediment accumulating on and around these features is a function of the depth of crestal portions of submarine highs. Third order provinces constitute a narrow zone of terrigenous sediment around the rim of the North Pacific Basin. Included are the floors of the circum-Pacific trench system and a portion of the northeastern corner of the Pacific. Two are named: the Aleutian Trench and the Northeast Pacific Turbidite Provinces.
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