The ocean basins are the ultimate sink for all the material transported by rivers or blown by winds into the sea. In addition, the oceans produce large quantities of autochthonous biogenic material. In their areal extent, the sediments of the present-day deep ocean basins surpass by far all the other sedimentary environments. Even measured by volume and for a certain time slice, deep-sea sediments have presumably predominated over other sediment types, for example shelf deposits, for the last millions of years. However, in the ancient record, a large proportion of former deep-sea sediments is missing (cf. Sect. 11.7). They were either subducted at convergent plate margins, or incorporated into accretionary prisms and orogenic belts and partially transformed into metamorphic rocks. After uplift, most of these rocks were eroded. Nevertheless, even in ancient rock sequences exposed on the continents, nonmetamorphic deep-sea sediments play a significant part. Their identification and interpretation are an important objective in basin studies and paleogeographic reconstructions.
KeywordsBottom Water Oxygen Minimum Zone Estuarine Circulation Axial Trough Sedimentary History
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