The Mineralogy of Marine Sediments
Those grains that were originally formed on the continents and have subsequently been transported into the ocean. River transport is the most important mechanism in which terrigenous minerals are passed to the ocean realm. Milliman & Meade (1983) estimate that about 12–13 × 109 tonnes of suspended sediment are supplied to the oceans by rivers annually and that a further 1–2 × 109 tonnes are supplied by bedload and flood discharges. If this amount were evenly distributed on the ocean floor, it alone would account for a sedimentation rate of over 3 cm per 1000 year (Dietrich et al., 1980). However, the actual increase in deep-sea sediments is much lower, as much of the terrigenous material is deposited on the continental shelf and rise. Other important pathways by which detrital minerals are passed to the deep sea are ice-rafting and aeolian transport, although these mechanisms are much less important volumetrically than river transport. Garrels & MacKenzie (1971) give an estimate of 0·06 × 109 tonnes/year for the total mass of material conveyed by aeolian transport to the oceans and 2 × 109 tonnes/year for ice-rafting. The most common detrital mineral in deep-ocean sediments is quartz derived from the weathering of continental rocks.
KeywordsMarine Sediment Ocean Drill Program Minor Modifier Pelagic Sediment Authigenic Mineral
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