Soft-sediment deformation structures

Cross-sectional view of deformed beds caused by soft-sediment deformation in the Booti Booti Sandstone (Mississippian), New South Wales. (Rygel, M.C.)
Aztec Sandstone (Lower Jurassic) in southern Nevada showing distorted eolian sand beds.
Large soft sediment deformation structures in turbidites, SE Spain. These are probably best described as flame structures, or perhaps ball-and-pillow structures. Backpack is around half a meter high. A small reverse fault runs through the outcrop in the centre of the image.

Soft-sediment deformation structures develop at deposition or shortly after, during the first stages of the sediment's consolidation. This is because the sediments need to be "liquid-like" or unsolidified for the deformation to occur. These formations have also been put into a category called water-escape structures by Lowe (1975). The most common places for soft-sediment deformations to materialize are in deep water basins with turbidity currents, rivers, deltas, and shallow-marine areas with storm impacted conditions. This is because these environments have high deposition rates, which allows the sediments to pack loosely.[1]

  1. ^ Allen, John R. L. Sedimentary Structures, Their Character and Physical Basis. Vol. 2. Amsterdam: Elsevier Scientific Pub., 1982. Print