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Herein, 20 ichnospecies belonging to 8 ichnogenera were identified in bivalves, gastropods, and corals (n = 701) from the Late Pleistocene coral reef along the Red Sea coast, northwest Saudi Arabia. The trace fossils were produced by clionid sponges (47.39%), endolithic bivalves (42.17%), polychaete annelids (5.42%), vermetid gastropods (3.81%), and acrothoracican barnacles (1.21%). The recognized ichnotaxa were Entobia geometrica, E. ovula, E. cf. goniodes, E. cf. retiformis, E. cretacea, Entobia isp., Gastrochaenolites torpedo, G. lapidicus, G. cf. dijugus, Gastrochaenolites isp., Oichnus paraboloides, O. simplex, Oichnus isp., Caulostrepsis taeniola, Caulostrepsis isp., Maeandropolydora cf. sulcans, Maeandropolydora isp., Renichnus isp., Centrichnus isp., and cf. Rogerella isp., Most bivalves and gastropods contain Entobia rather than Gastrochaenolites, which is commonly found in the larger and thicker corals. The content of the trace fossils indicated an Entobia ichnofacies formed in the coral reef during transgression. The habitat conditions changed gradually, from well-oxygenated, shallow, high-energy back-reef and reef crest bioeroding polychaetes and bivalves, to deep, low-energy reef slope dominated by boring sponges. [ABSTRACT FROM AUTHOR]

The Late Pleistocene reef unit of the last interglacial marine isotope stage 5e stretches all over most of the coastal cliffs and wadi cuts and interrupted only in wadi entrances along the Red Sea coast, northwest Saudi Arabia. It studied and sampled from 12 localities between Duba and Sharma for micro-and macrofossils record. Twenty-four foraminifera, 67 coral, 79 gastropod and 63 bivalve species were identified. The identified assemblages, particularly scleractinians indicated a deepening upward pattern for the studied late Pleistocene reef unit, starting with a coral assemblage of coral rock zone at the base, above a conglomeratic bed, followed by reef crest facies, and grades into the upper reef slope assemblages. The recorded taxa mostly have the Indo-Pacific affinity, and few elements have Atlantic-Mediterranean and cosmopolitan realm. [ABSTRACT FROM AUTHOR]

Middle to Late Pleistocene coral reefs stretch in three discontinuously elevated units above the present sea level between Duba and Sharma along the Red Sea coast, northwest Saudi Arabia. They correspond to MIS 5, MIS 7, and MIS 9 of the deep sea cores. Each unit exhibits prominent terraces as a result of the onlap during different sea levels, erosion during transgression, and tectonic uplift. Framestones, bafflestones, bindstones, packstones, grainstones and floatstones of coral, algal, and other bioclasts are the main microfacies types recorded from these reefal units and their internal sediment. The lower and the upper units exhibited a vertical pattern of a transgressive sequence, starting at the base with a coral assemblage of coral rock zone and graded into the upper reef slope community at the top, while the middle one exhibited a regressive sequence. Corals progressively changed from aragonite in the lower unit to calcite in the upper one by meteoric leaching of the trabeculae, and the cements changed from marine aragonitic needles and peloidal Mg‐calcite in the lower unit to blocky and dog teeth cements and silica in the middle and upper units. The gravel lenses within coral colonies of the upper unit with plagioclase, epidote, and fractured quartz grains are attributed to a granitic province from the hinterland mountains, driven to the reef during rainy periods. [ABSTRACT FROM AUTHOR]

This paper reports a deep-water coral framework (a single colonial bush or a larger bioconstruction of coral covering the sea bottom), formed entirely by the scleractinian coral Eguchipsammia fistula (Alcock, 1902) (Dendrophylliidae), in the northern Red Sea waters of Saudi Arabia at a depth of about 640 m. The framework consists of mostly live corals with a total area of about 10 m 2 and the length of the individual coral branches range from 12 to 30 cm. Although E. fistula is ubiquitous, this discovery is the second record of a framework formed by this species and the first discovery of a large living reef in the Red Sea. The results of the genetic study indicate the potential existence of a genetic variation of E. fistula in the Red Sea. This discovery implies that the Red Sea has favorable habitats for framework-forming DWC species and highlights the need for conducting more systematic surveys for understanding their distribution, abundance, and ecology.