Macrofaunal communities and microfacies analysis of the upper Campanian-Maastrichtian Sudr Formation at the Galala Plateaus, north Eastern Desert, Egypt: paleoenvironmental and paleobiogeographical implications

Abstract

The Upper Cretaceous deposits are widely distributed and well exposed in northern Egypt. Important upper Campanian-Maastrichtian carbonate deposits outcrop at the Northern and Southern Galala Plateaus, north Eastern Desert, represented by Sudr Formation. Sudr Formation is lithologically investigated, sampled, and the included fauna are collected for taxonomic and paleobiogeographic studies. Four gastropod species, belonging to three genera and three families, as well as twelve bivalve species, representative of twelve genera and nine families, are identified. Two gastropod species; Cerithium buddha Noetling, Potamides temalacaensis Perrilliat et al., and four bivalve species; Gryphaeostrea canaliculata (Sowerby), Venilicardia truncata (Sowerby), Calva (Egelicalva) buttensis (Anderson), Lyriochlamys dentata (Nilsson), are recorded for the first time from the Upper Cretaceous deposits of Egypt. The microfacies analysis of the carbonates of Sudr Formation revealed four distinct microfacies types, each with characteristic bioclasts and textural features. These microfacies types suggest open-marine, high-energy shallow subtidal shoal to low-energy deep subtidal environments. The paleobiogeography of the recorded bivalve taxa is highlighted, revealing two endemic species to Egypt; Nucula chargensis Quaas and Meretrix rohlfsi (Quaas). On the other hand, the other identified bivalve species show wide distribution over a broad geographical