Sedimentary patterns and hydrodynamic transport processes on modern carbonate platforms in arid climates are understudied compared to platforms in humid-tropical climates. The Al Wajh platform – located in the Arabian–African desert belt – is a large land-attached carbonate platform in the Red Sea providing an excellent opportunity to fill this gap. The platform covers some 1800 km² and is almost completely enclosed by a 115 km long reef-shoal belt. More than 200 sediment surface samples were analyzed in order to investigate the lateral sediment distribution within the lagoon. The seafloor map was refined integrating sample depths with previous published bathymetric information. Conductivity and temperature profiles were measured to study the lagoonal water body. The lagoon is dominated by poorly sorted, sand-sized sediments with low total organic carbon content, while carbonate fines content shows significant lateral variation. Aragonite dominates sediment mineralogy with high-Mg calcite and low-Mg calcite being significant admixtures. Fine-grained siliciclastics are found across the entire lagoon, with angular quartz locally enriched in near-shore and distal areas. Seven component assemblages are defined ranging from benthic foraminifera and mollusc-rich to reef debris-rich component assemblages. Platform-interior ooids are for the first time documented from the modern Red Sea. The heterogeneous distribution of carbonate fines shows no water depth related trends, while the component assemblage arrangement is depth related. Hydrodynamics are interpreted to be the main mechanism controlling carbonate fines distribution in the lagoon. A near-shore enrichment of angular sand-sized quartz suggests influx through wadis during flash floods, while an almost even distribution of fine-grained siliciclastics possibly indicate aeolian import. These findings provide new insights to the importance of hydrodynamic transport processes for sediment distribution in a land-attached platform lagoons in an arid climate. Finally, this study presents a comparison with other modern platforms and discusses implications for improving strategies of hydrocarbon field development in rift-basin carbonates.
|Original language||English (US)|
|State||Published - Nov 6 2021|
Bibliographical noteKAUST Repository Item: Exported on 2021-11-11
Acknowledgements: M. Prada is funded by the Beatriu de Pinós postdoctoral programme of the Government of Catalonia’s Secretariat for Universities and Research of the Ministry of Economy and Knowledge (Ref # 2017BP00170). J.P.A. is supported by the Investments in the Future project UCAJEDI (ANR-15-IDEX-01) managed by the French National Research Agency (ANR). First author and ICM have had funding support of the “Severo Ochoa Centre of Excellence” accreditation (CEX2019-000928-S) of the Spanish Research Agency (AEI). We thank Florian Le Pape for his assistance during the generation of the bimaterial unstructured mesh. We thank the associate editor Yehuda Ben-Zion, and two anonymous reviewers for their comments that help to improve the manuscript. Dynamic rupture simulations in this study were done at the Super Computer Shaheen II at KAUST University. Shaheen II is a Cray XC40 delivering over 7.2 Pflop/s of theoretical peak performance. Overall, the system has a total of 197,568 processor cores and 790 TB of aggregate memory. Tsunami-HySEA code development is supported by the Spanish Government-FEDER funded project MEGAFLOW (RTI2018-096064-B-C21).
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