Pelagic sediment | geology | Britannica (original) (raw)
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Atlantic Ocean
In Atlantic Ocean: Bottom deposits …by several inches of normal pelagic sediment. Study of the shells of planktonic foraminifera in these cores shows that the climatic changes, ice ages, and interglacial ages of the last two million years have been recorded in the sediments as alternations of species adapted to cold or to warm water.… Read More
composition minerals
In sedimentary rock: General properties of shales In pelagic (deep-sea) sediments, however, feldspar may be derived from local volcanic sources, whereas quartz may be introduced from the continents by wind, upsetting simple patterns. A large number of accessory minerals occur in shales. Some of these are detrital, but diagenetic or in situ varieties… Read More
marine sediments
In marine sediment …slowly accumulating deposits known as pelagic sediments. Because of its great distance from the continents, the abyssal plain does not receive turbidity currents and their associated coarse-grained sediments. Moreover, since relatively little land-derived sediment consisting of silicate mineral and rock fragments reach the ocean bottom, deposits there show a predominance… Read More
In ocean basin: Sediment types Pelagic sediments, either terrigenous or biogenic, are those that are deposited very slowly in the open ocean either by settling through the volume of oceanic water or by precipitation. The sinking rates of pelagic sediment grains are extremely slow because they ordinarily are no larger… Read More
presence in bathyal zone
In bathyal zone Bathyal sediments are terrestrial, pelagic, or authigenic (formed in place). Terrestrial (or land-derived) sediments are predominantly clays and silts and are commonly coloured blue because of accumulated organic debris as well as bacterially produced ferrous iron sulfides. Coarser terrigenous sediments are also brought to the bathyal seafloor by sporadic… Read More
