What is sabkha geology?
The sabkhas (Arabic for area of low-lying salty ground) are broad intertidal areas and coastal plains (Figures 9 and 10) that may be flooded by lagoon waters when storm winds blow landwards. From: Encyclopedia of Geology, 2005.
What is a sabkha environment?
1. n. [Geology] An environment of coastal sedimentation characterized by arid or semiarid conditions above the level of high tide and by the absence of vegetation. Evaporites, eolian deposits and tidal-flood deposits are common in sabkhas.
How do evaporites form in Sabkhas?
All evaporite deposits ultimately form from the evaporation of a fresh- or saltwater brine.
How Sabkha is formed?
If the features silt up, or the land rises, or the sea level falls, then the trapped water evaporates, leaving a flat salt pan, or sabkha. If the coastal region has irregular topography, then the flooding creates large independent creeks, or khors. A khor is a shallow, subtidal flat or tidal inlet.
How are evaporites deposited?
Typically, evaporite deposits occur in closed marine basins where evaporation exceeds inflow. The deposits often show a repeated sequence of minerals, indicating cyclic conditions with a mineralogy determined by solubility.
What are evaporites in geology?
evaporite, any of a variety of individual minerals found in the sedimentary deposit of soluble salts that results from the evaporation of water.
Is gypsum an evaporite mineral?
Minerals in evaporite rocks include carbonates (especially calcite, dolomite, magnesite, and aragonite), sulfates (anhydrite and gypsum), and chlorides (particularly halite, sylvite, and carnallite), as well as various borates, silicates, nitrates, and sulfocarbonates.
What process forms sandstone?
Sandstone forms from beds of sand laid down under the sea or in low-lying areas on the continents. As a bed of sand subsides into the earth’s crust , usually pressed down by over-lying sediments, it is heated and compressed.
What is the difference between evaporites and precipitates?
Evaporite rocks form when sea water or lake water dries up and precipitates gypsum (CaSO4·2H2O), halite (NaCl), or other minerals. Evaporites are chemical sedimentary rocks.