Bioerosion in the Miocene Reefs of the northwest Red Sea, Egypt

Abstract

2016: Bioerosion in the Miocene Reefs of the northwest Red Sea, Egypt. Lethaia, 49, Macroborings provide detailed information on the bioerosion, accretion and palaeoenvironment of both modern and fossil reefs. Dolomitized reefal carbonates in the Um Mahara Formation exhibit an outstanding example of spatially distributed, well-preserved bioerosion structures in tropical to subtropical syn-rift Miocene reefs. Ten ichnospecies belonging to five ichnogenera are identified; three belonging to the bivalve-boring ichnogenus Gastrochaenolites, three attributed to the sponge-boring ichnogenus Entobia, and four ichnospecies assigned to three worm-boring ichnogenera Trypanites, Maeandropolydora and Caulostrepsis. The distribution of the reported borings is strongly linked to the palaeo-reef zones. Two distinctive ichnological boring assemblages are recognized. The Gastrochaenolites-dominated assemblage reflects shallower-marine conditions, under water depths of a few metres, mostly in back-reef to patch-reef zones of a back-reef lagoon. The Entobia-dominated assemblage signifies relatively deeper marine conditions, mostly in reef core of the fringing Miocene reefs. These ichnological assemblages are attributed herein to the Entobia sub-ichnofacies of the Trypanites ichnofacies. This ichnofacies indicates boring in hard carbonate substrates (such as corals, rhodoliths, carbonate cements and hardgrounds) during periods of non-sedimentation or reduced sediment input. □ Egypt, Miocene reefs, Red Sea, Um Mahara Formation. Zaki A. Abdel-Fattah [zabdelfattah@gmail.com], and Ehab M. Assal [ehab.assal@

Trypanites ichnofacies and its multifarious significance: A case study from the Miocene Boka Bil Formation of Manipur, India

“…The Trypanites Ichnofacies ranges in age from the Early Cambrian to the Holocene (Taylor & Wilson, 2003; Wilson, 2007), and in the geological past, this ichnofacies peaked during the Ordovician, Devonian, Jurassic and Tertiary (Wilson, 2007). However, it is concluded here that during the Miocene, the Trypanites Ichnofacies was at its peak, as manifested by publications from different countries (Abdel-Fattah & Assal, 2016; Belaústegui et al, 2012; Bromley & D’Alessandro, 1984; Demircan, 2012; Demircan et al, 2021; Domènech et al, 2001; El-Hedeny & El-Sabbagh, 2018; Farinati & Kulkarni et al, 2007; Johnson et al, 2010; Patel & Shringarpure, 1998; Radwański, 1969, 1970; Radwański et al, 2011; Santos and Mayoral, 2008; Santos et al, 2008, 2010, 2011; Uchman et al, 2018, 2002; Naimi et al, 2021; Zavala, 2002;). In the context of NE India, Mehrotra et al (2001) recorded a solitary macroboring, Teredolites clavatus , from the Miocene Bhuban Formation of the Aizawl, Mizoram.…”

“…Entobia ranges in age from the Devonian to the Holocene (Bromley, 1970, 2004; Bromley & D’Alessandro, 1984, 1989; Buatois et al, 2016; Fursich et al, 1994; Mikuláš, 1992; Taylor & Wilson, 2003; Wilson, 2007). Entobia cateniformis is known from the Early Pleistocene Calcarenite di Gravina Formation, Italy (Bromley & D’Alessandro, 1984); the Early Miocene Chhasra Formation of Kachchh, India (Kulkarni et al, 2007); the Middle Miocene of Ukraine (Radwański et al, 2011); the Miocene rocky shore of Concepción Formation, México (Pineda-Salgado et al, 2015); the Miocene reefs of the northwest Red Sea, Egypt (Abdel-Fattah & Assal, 2016) and the Early Eocene of Kachchh Basin, India (Gurav & Kulkarni, 2018).…”

“…Remark: Entobia ovula is known from the Miocene rocky shore in southern Iberia (Santos et al, 2008); the Miocene rocky shore in south Spain (Santos et al, 2011); the Miocene Reefs of the northwest Red Sea, Egypt (Abdel-Fattah & Assal, 2016); the Middle Miocene of the northern Western Desert of Egypt (El-Hedeny & El-Sabbagh, 2018); the early Eocene of Kachchh Basin, India (Gurav & Kulkarni, 2018) and the late Pleistocene of Red Sea Coast, Saudi Arabia (Demircan et al, 2021).…”

“…Remarks: Gastrochaenolites lapidicus is known from the Pliocene of the northwestern Mediterranean (Gibert et al, 1998); the Pliocene of Gujarat, India (Kulkarni et al, 2008); the Miocene rocky shores in southern Iberia (Santos et al, 2008); the Miocene Reefs of the northwest Red Sea, Egypt (Abdel-Fattah & Assal, 2016); the Middle Miocene of the northern Western Desert of Egypt (El-Hedeny & El-Sabbagh, 2018); the Early Oligocene of the Tertiary Piedmont Basin, Italy (Uchman et al, 2017); the Middle Miocene of the Carpathians, Poland (Uchman et al, 2018) and the Late Pleistocene of the Red Sea Coast, Saudi Arabia (Demircan et al, 2021).…”

“…Remarks: Gastrochaenolites torpedo is known from the Miocene rocky shores of many regions in Europe and neighbouring areas (Radwański, 1969); the Pliocene of the northwestern Mediterranean (Gibert et al, 1998); the Pliocene of Gujarat, India (Kulkarni et al, 2008); the Miocene of Mut Basin, Turkey (Uchman et al, 2002); the Miocene rocky shores in southern Iberia (Santos et al, 2008); the Miocene of Lower Tagus Basin, Portugal (Santos et al, 2010); the Late Miocene rocky shores from Menorca (Balearic Islands), Spain (Johnson et al, 2010); the Late Miocene of Cannakale, Turkey (Demircan, 2012); the Miocene Reefs of the northwest Red Sea, Egypt (Abdel-Fattah & Assal, 2016); the Early Oligocene of Tertiary Piedmont Basin, Italy (Uchman et al, 2017); the Middle Miocene of the northern Western Desert of Egypt (El-Hedeny & El-Sabbagh, 2018); the Middle Miocene of the Carpathians, Poland (Uchman et al, 2018) and Late Pleistocene of Red Sea Coast, Saudi Arabia (Demircan et al, 2021).…”