Sedimentology and mineralogy of the Al-Hammar Marsh / Southern Iraq: A review

Abstract

The sediments of Ahwar area are mainly clayey silt with small amount of sand. The sand fraction is of fine to very fine grains. The color of these sediments is influenced by the hydrodynamic nature of the environment, and the organic content. The surface sediments are divided into three main layers; a surface organic – rich sand silty layer to a depth 7cm, shelly clayey silt layer from 7 to 30cm in depth, and silty clay or/and clay layer more than 30cm in depth. The dominant sedimentary structures are bioturbation and lamination. The heavy and light mineral assemblages reflect the origin of these sediments which is the ancient outcrops transported by Tigris and Euphrates Rivers. Low – Mg calcite, High – Mg calcite, dolomite and gypsum minerals are also present and considered as authigenic minerals. The detected clay mineral assemblage is smectite, chlorite, illite, mixed layer illite-smectite and kaolinite,in addition to palygorskite as authigenic and allogenic mineral.