Late Holocene Red Sea Coastal Evolution: Evidence from Shallow Subsurface Sedimentary Facies, North Al-Wajh, Saudi Arabi

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Late Holocene Red Sea Coastal Evolution: Evidence from Shallow Subsurface Sedimentary Facies, North Al-Wajh, Saudi Arabia Ibrahim M. Ghandour 1,2 & Jawad Majeed 1 & Aaid G. Al-Zubieri 1,3 Rashad A. Bantan 1

&

Ammar A. Mannaa 1 & Mohammed H. Aljahdali 1 &

Received: 27 November 2019 / Revised: 11 August 2020 / Accepted: 13 August 2020 # Springer Nature Switzerland AG 2020

Abstract The stratigraphy of the late Holocene shallow subsurface coastal sediments, North Al-Wajh, Saudi Arabia was investigated to reconstruct the environmental evolution of the area in relation to sea-level changes. Five shallow cores (1.1 to 2.2 m long) were collected from the intertidal flat bordering the Dumaygh Lagoon, and the mouths of wadis Antar and Haramil. The cores exhibit siliciclastic-dominated sediments, in some parts containing reworked calcareous shell fragments of bivalves, gastropods and coral remains. The sediments were analyzed for grain size, loss on ignition (LOI), CaCO3 content, and bulk mineralogy. Mineralogically, the sediments were dominated by siliciclastic minerals (quartz, plagioclase, feldspars, and hornblende) followed by low Mg-calcite (LMC), high Mg-calcite (HMC) and aragonite. In addition, traces of mica, amphiboles, clay minerals, and dolomite were recognized. There is a slight lateral variation in the relative abundance of aragonite and high Mg calcite (HMC), particularly at the base of cores. The results provide a simple scenario for the late Holocene Northern Red Sea coastal evolution. Two vertically stacked sedimentary facies were recognized from the cores; grey mud-dominated lagoonal/bayfill at the base and yellowish-brown sand-dominated intertidal flat at the top. The vertical facies stacking suggests a forestepping pattern or progradational sequence possibly attributed to the late Holocene relative sea-level fall. Keywords Red Sea coastal evolution . Late Holocene sea-level fall . Sedimentary facies, arid coasts . Mineralogical composition

Introduction The vertical and lateral distribution of shallow subsurface coastal sedimentary facies provides essential information on the coastal evolution, particularly those related to changes in climate and relative sea-level (Hein 2012; Ghandour and

Electronic supplementary material The online version of this article (https://doi.org/10.1007/s41208-020-00248-2) contains supplementary material, which is available to authorized users. * Ibrahim M. Ghandour [email protected] * Aaid G. Al-Zubieri [email protected] 1

Faculty of Marine Sciences, Marine Geology Department, King Abdulaziz University, Jeddah, Saudi Arabia

2

Faculty of Sciences, Geology Department, Tanta University, Tanta 31527, Egypt

3

Faculty of Marine Sciences and Environments, Marine Geology Departments, Hodeidah University, Hodeidah, Yemen

Haredy 2019). The coastal morpho-sedimentary units exhibit a highly variable stratigraphic architecture, reflecting the influence of variations in sedimentation rate, accommodation space, coastal processes, shore zone morphology and basin physiogr