Locality 10

Salt Flat

Extensive sand or mud flats (inland sabkhas) are particularly characteristic of saline lakes.

These are very low gradient features, which merge landwards into alluvial fans or talus aprons along mountain fronts, or where relief is low, into alluvial or desert plains, and lakeward into a saline or ephemeral water body.

The flats are dry for much of the time, being covered by water only during periods of flood or high lake level. Most of the sediment is of fluvial origin, introduced by unconfined sheet floods, although wind blown dust, trapped on sticky hygroscopic surface, may also make a significant contribution (Reading, 1996).

The deposits are horizontally or wavy laminated, however, they are frequently subjected to prolonged periods of exposure.

Desiccation causes extensive breaking. Salt crusts form at the surface and interstitial precipitation of evaporites from saline groundwaters or springs may deform the lamination.

Photo of salt flat at Umm Said Quatar

source http://www.soton.ac.uk/~imw/sabkha.htm

Salt flat at Umm Said Quatar

Bioturbation due to the growth of halophyte vegetation and the activities of salt tolerant insects such as ants and multiple cycles of precipitation and dissolution of salt minerals can lead to a massive apparently structurless mudstone or siltstone.

Collapse due to salt dissolution can also result in the development of a characteristic sand-patch fabric.

Desiccation salt heaving and the formation of efflorescent crusts make exposed surfaces prone to deflation. Can be a source of aeolian dust, but abundant sand sized clay pellets, which accumulate around the margins of some salt lakes as a distinctive aeolian sediment body (Reading, 1996).




This page was created by Pamela Williams

Last Modified:18/06/02