EARTH 222 Lecture Notes - Lecture 4: Manganese, Silt, Ocean Current
11 Jun 2016
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Document Summary
What are marine sediments: particles of various sizes derived from a variety of sources that are deposited on the ocean floor, a vast library recording geologic, oceanographic, and climatic conditions, remarkably complete compared to land. Inputs are: rivers, wind, surface waters, volcanoes (both on land and submarine, deep ocean water, outer space. Classification of marine seds by source: terrigenous sediments: erosion of continents, volcanic ash (volcanogenic, biogenous sediments: formed biologically in the ocean (e. g. seashells, whole or fragments, hydrogenous sediments: precipitate (crystallize) from seawater, cosmogenous sediments: dust from space. These sediments consist of fragments (clasts) produced by: weathering (break-down) of pre-existing rocks. Physical reduces rocks to smaller fragments. Chemical dissolves minerals in rocks: erosion, transport and deposition by physical processes (running water, glaciers, wind, and gravity). Terrigenous sediments are the most common marine sediment type by mass. Sources: rivers, winds (eolian, glaciers (ice-rafted debris, turbidity currents, volcanic eruptions.
