Sources of beach sand from the central and eastern coasts of Ghana, West Africa
Sources of beach sand from the central and eastern coasts of Ghana were determined by a comparative approach using: (1) presence or absence of unique mineral grains; (2) abundance of common mineral components; and (3) correlation of textural parameters of sediments. On the Ghana coast, glauconite grains are considered as an exclusively shelf-derived mineral grains whereas staurolite, garnet and ilmenite are exclusively shore-derived minerals. The presence of only shore-derived minerals in the beach sand indicates a continental origin. Similarities in composition and texture exist between the beach sand and unconsolidated Quaternary sediments exposed at the shoreline. Contribution of sand to the beach budget from these Quaternary outcrops along the coasts has resulted in shoreline retreat. The model of late Quaternary sedimentation on the central and eastern coasts of Ghana can be constructed from the history of the coastline development. The model began with an allochthonous sedimentation during which a shoreline progradation occurred. This sedimentation was followed by an autochtonous sedimentation when the supply of sand from the rivers declined. This latter sedimentation characterized by a shoreline retreat is now active on the coasts.
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