Geomorphological and sedimentological characteristics of coastal and inland sabkhas, Southern Kuwait

Abstract

Sabkha deposits in the southern sector of Kuwait occur as scattered, irregular, and closed lowland areas of different sizes. On the basis of their field occurrence, and geographic setting two distinct types of sabkhas are recognized, coastal and inland. The coastal sabkhas extend along the elongated depression in Al-Jailaiaha and Al-Khiran areas. The inland sabkhas are formed in the irregular slopes in the western side of the desert area in Al-Maqwa, Urafjan, and Al-Gurain areas. Formation of sabkhas is related to pre-existing morphological features such as depressions and gentle slopes, and is distributed in the study area in different geomorphological zones. Both coastal and inland sabkhas are subjected to mobile sand invasion under the action of the northwesterly prevailing wind. Texturally, both groups of sabkhas may be classified within the gravelly to slightly gravelly muddy sand class. Their sediments are mostly unimodal with a modal class of medium sand, poorly sorted, nearly symmetrical and mesokurtic. The surface features of quartz grains show the mechanical and chemical action on their surfaces. Mineralogically, coastal and inland sabkhas are mainly composed of quartz, feldspars, gypsum and rock fragments, which are mostly of carbonate type. Skeletal fragments and oolites are present in the coastal sabkhas and are absent in the inland sabkhas. Based on the heavy-mineral suites, most of sabkha sediments are thought to be derived from Al-Dibdibbah deposits, which were derived from the Arabian Shield igneous and metamorphic rocks by wadi A1-Rimmah-Al-Batin valley system.