Deep-sea contourites: Sediments and cycles

Citation

Stow D, Smillie Z, Pan J & Esentia I (2019) Deep-sea contourites: Sediments and cycles. In: Cochran JK, Bokuniewicz H & Yager P (eds.) Encyclopedia of Ocean Sciences, Vol. 4. 3rd edn ed. Reference Module in Earth Systems and Environmental Sciences. Academic Press, pp. 111-120. https://doi.org/10.1016/B978-0-12-409548-9.10879-6

Abstract
Contourites are one of the three principal types of sediment that cover the deep seafloor. They are the result of erosion, transport and deposition by deep ocean bottom currents, which, over millions of years, can construct giant sediment drifts over 1000 m in thickness. These hold a permanent record of past changes in ocean environment and climate. Cyclic variation in the structural, textural, and compositional properties of contourites are expressed as a series of 0.5–5 m thick bi-gradational sequences, each of which takes several millennia of continuous deposition by slow to medium velocity currents. Stronger bottom currents winnow and erode the seafloor, resulting in broad sand sheets.

Keywords
Ancient contourite; Bottom current; Calcareous contourite; Contourite; Contourite controversies; Contourite facies; Cyclicity; Facies model; Muddy contourite; Sandy contourite; Sediment drift