Analysis of Quaternary Sediments of Quartz Grains Applied to the Identification of the Environment of Some Ivory Beaches East of Abidjan (Côte d'Ivoire)

ABSTRACT

Morphoscopic and exoscopic analysis of quartz grains collected on the Ivorian beaches of the gulf of Guinea between Abidjan (Côte d'Ivoire) and Aforenou (Ghana) during topographic surveys between March 2007 and March 2009 on the examination of quartz at the binocular loupe, reveals blunting grains shining on all beaches (50% to 70%). In Abidjan area, the majority of the grains are reddish, indicates a ferrous and inherited environment. The exoscopy for the fine and detailed study of the morphology and the surface of the quartz grains was made with the Scanning Electron Microscope (SEM). This approach makes it possible to interpret traces related to events (energy level) or environments (transport, transition and storage environments). These observations indicate that the quartz after a long transport in a fluvial environment have been reworked in a marine environment. They were finally deposited in a low-energy aquatic continental medium marked by the polishing of the crystalline points and the siliceous corpuscles dotting the surface of the grains. The energy of the transport environments crossed is high in a turbulent environment through traces of shock, as large and numerous as they are. SEM examination of the samples reveals that beach quartz has generally been transported by river and recovered in an intertidal and/or subtidal environment. They have a continental and marine origin.