MEA 200 Lecture Notes - Lecture 5: Pelagic Sediment, Diatomaceous Earth, Ice Rafting
30 Mar 2017
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Document Summary
One of the most important sediment properties. Proportional to energy of transportation and deposition. Classified by wentworth scale of grain size. High energy (strong wave action) larger particles. Hydrogenous or authigenic derived from water. Types of sediment: lithogenic sediment (aka terrigenous) Origin: weathering and erosion of continental rocks. Composition: grains of igneous, metamorphic, and sedimentary rocks. Reflect composition of rock from which derived. Rivers & streams 85% transported by rivers. Neritic sediments (shallow water) cover about of the sea floor. Pelagic sediments (deep water) cover about of the sea floor. Fine-grained material transported by deep ocean currents. At least 70% clay sized particles from continents. Abundant if other sediments absent: biogenic sediment (types of sediment) Composition: skeletal material made of caco3 (calcium carbonate) or sio2 (silica) Sea floor sediments represent surface ocean conditions. Microscopic particles sink slowly from surface ocean to sea floor (10 50 years) Most biogenous particles clump together in fecal pellets.
