- siliceous material also dissolves a bit in seawater, but much more slowly than carbonate material. They are present chiefly above a depth of 4,500 metres (about 14,800 feet); below that they dissolve quickly. An ooze that is primarily calcium carbonate (aragonite or calcite), a calcareous ooze, typically turns into a rock of the limestone group. Areas of the ocean that lie beneath the carbonate compensation depth (CCD), below which calcium carbonate dissolves, typically beneath 4-5 km, will be dominated by Because of the proximity of the basin to the Carbonate Compensation Depth (C.C.D. ), surface sediments vary between calcareous oozes and siliceous muds. a siliceous-based ooze. They are overlain by foraminiferal ooze deposited on the shallower seafloor of the mid-ocean ridge, with the sedimentation rate and the proportion of siliceous organisms depending on latitude. (ii) Pteropod ooze contains protective shells of pelagic molluscs; (iii) Coccolith ooze contains large number of coccoliths and rhabdoliths that form the protective structures of the minute coccolithophoridae. They are even found at depth of 4-5km covering extensive areas in abyssal plains for which the sediments found there are termed as siliceous ooze. Siliceous oozes often contain lesser proportions of either sponge spicules, silicoflagellates or both. Siliceous oozes are particularly prominent across areas of the ocean floor located far from continental blocks, where the rate of terrigenous sediment supply is low, and in deeper parts of the abyssal plain lying below the carbonate compensation depth, where the accumulation of calcareous oozes cannot occur. Below the CCD, only dust and silica can deposit, as the calcareous organisms dissolve before reaching the sea floor, and siliceous ooze accumulates more quickly than red clays. Siliceous ooze, Foraminifera, Diatoms, Radiolaria, Carbonate compensation depth Grade Level: 9-12 Lesson Time: 1 hr. Materials Required: global map, Sediment Distribution Patterns map Science as Inquiry Abilities necessary to do scientific inquiry (K -4, 5 -8, 9 -12) This type of ooze accumulates on the ocean floor at depths below the carbonate compensation depth. The ooze composed of their hard parts accumulates at a rate of about 10mm - 50mm per thousand years, varying from location to location; which doesn't sound like much, but is actually a faster rate than other marine sediments such as siliceous ooze or pelagic clay. Chert is derived from a siliceous ooze. As a result, the majority of deep marine deposits are of siliceous ooze, which lithifies as chert. Siliceous oozes are formed under upwelling zones. Carbonate oozes cover about half of the world’s seafloor. (B) Siliceous oozes: These pelagic deposits are formed by a large percentage of siliceous skeletal material produced by planktonic plants and animals. The top of the opal-A dominated siliceous ooze is at ∼1,745 m. The opal-CT contact is at ∼1,993 m (Table 1). Carbonate oozes dominate the deep Atlantic seafloor, while siliceous oozes are most common in the Pacific; the floor of the Indian Ocean is covered by a combination of the two. The composition of ooze depends on details of geography: ocean currents, the availability of nutrients in the water, world climate, depth in the ocean, and other factors. Cite 12th Jul, 2018 WikiMatrix Ooze is pelagic sediment that consists of at least 30% of microscopic remains of either calcareous or siliceous planktonic debris organisms. Further, factors such as depth, temperature, and pressure can affect the ability of calcium carbonate to dissolve. 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