Abstract

Proposed criteria for the identification of ancient sandy contourites include occurrence (thin beds, reworked sandy turbidites, coarse lag), structure (bioturbated, no regular vertical sequence, orientation of cross-lamination perpendicular to regional downslope paleocurrents), grain size (silt or sand, little mud, low or negative skewness), fabric (grain orientation), and composition (downslope and along-slope provenance, concentrations of heavy minerals). A suggested three-stage approach to recognition of sandy contourites in the field involves work on a progressively increasing scale, with particular emphasis on paleocurrent data. The various deep-water settings in which disparate current directions may occur are summarized, and those in which sandy contourites may be formed and recognizably preserved are indicated. A broad definition of the term “contourite” is now possible because of the widespread documentation of contourites even in freshwater environments. Along-slope flow that is persistent in time and space is a requirement.

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