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Contourite
A contourite is a sedimentary deposit produced by thermohaline-induced deepwater bottom currents and may be influenced by wind or tidal forces.〔(Rebesco, M. & Camerlenghi, A. 2008. Contourites, Elsevier Science, 688pp. ISBN 978-0-444-52998-5 )〕 Most contourites are formed in continental rise to lower slope settings, although they may occur anywhere that is below storm wave base. The geomorphology of contourite deposits is mainly influenced by the deepwater bottom-current velocity, sediment supply, and seafloor topography.
==Definition==
The definition of the term contourite has varied throughout the decades. Originally, Heezen ''et al.'' (1966) defined the concept, without using the actual word, as a sedimentary deposit on the continental rise derived from thermohaline-induced geostrophic bottom-currents that flow parallel to bathymetric contours. They did this to emphasize the difference between these deposits and turbidites in order to explain the ubiquitous smoothness and lack of irregularities of the continental rise in the Blake-Bahama Basin. Before this, it was thought that only turbidity flows were capable of depositing and reworking sediment at depths greater than the continental slope.〔 Hollister and Heezen (1972) adopted the name contourite for these deposits and provided a list of characteristics that described their sediments. Faugères and Stow (1993) note that as research on the subject developed, the term contourite was used to describe various forms of sedimentary deposits from bottom-currents including those at much shallower depths and even in lacustrine settings. They suggested going back to the original definition of a contourite, that is for deposits at depths greater than 500 m derived from stable thermohaline-induced geostrophic bottom-currents (i.e. deepwater bottom-currents), in order to avoid using the same name when describing sedimentary deposits formed by different processes. They also suggest the umbrella term bottom-current deposit, which includes contourites and deposits generated by other bottom-currents.
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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