Facies Analysis and Sequence Stratigraphy of Al-Kharrar Lagoon Coastal Sediments, Rabigh Area, Saudi Arabia: Impact of Sea-Level and Climate Changes on Coastal Evolution

This study employs the results of facies analyses and sequence stratigraphy of the coastal plain sediments of Al-Kharrar Lagoon, Rabigh, Saudi Arabia, to interpret the impact of Late Quaternary sea-level and climate changes on sedimentation, facies distribution and Red Sea coastal evolution. Facies analysis of the sediments that crop out in a recently excavated quarry section and those recovered from six shallow cores obtained from the tidal flat south Al-Kharrar Lagoon enabled identifying four facies associations characterizing fluvial, intertidal-supratidal, lagoonal and intertidal flat deposits. Facies architecture and sequence stratigraphic interpretations indicate two distinct depositional stages. The first stage included the deposition of marine-influenced gravel-dominated fluvial channel deposits interdigitating with or overlain by grey lagoonal mud and fine sands suggesting deposition during a period of progressive sea-level rise and enhanced precipitation. The second stage records deposition of prograding intertidal-supratidal deposits containing calcareous nodules and mottles and evaporite minerals at quarry section suggesting deposition during a sea-level fall under an arid climate. The results of this study are correlated with the Late Quaternary periods of humidity and aridity. It is found that the first stage corresponds to the postglacial early-middle Holocene sea-level rise and wet climate, whereas the second stage corresponds to the mid-to late Holocene isostatically controlled sea-level fall and arid climate.