Turbidites

deposits from turbidity currents on the floor of the seas and oceans, consisting of clastic sediments of various sizes and different degrees of roundness.

The periodic deposition of sediments from turbidity currents on the sea floor disrupts the usual process of sedimentation and produces a series of cycles in sea-floor sediments; the boundaries of the cycles are usually distinct, and the thicknesses vary (usually a few tenths of a centimeter, less often fractions of a centimeter to several meters). In the lower part of each cycle the most coarsely grained sediments grade upward into more finely grained sediments, resulting in graded bedding. The cycle is completed by a thinner layer of argillaceous or carbonate pelitic sediment.

Different slope steepnesses, transport times, and degrees of turbidity-current loading or liquidity cause differences in the structure of turbidites. The remains of shallow-water and littoral organisms transported by a turbidity current are found in the deep-water sediment. The volcanogenic material tephra is sometimes present in turbidites; such sediments are called tephroturbidites. In mineral form they are known as tuff turbidites. Turbidites are widespread among recent and ancient deposits of various ages, especially among sediments in seismically active areas.