Biostratigraphy and paleoenvironmental setting of the Lower Miocene succession at the west central Sinai, Egypt

Abstract

Paleoenvironmental setting for the Lower Miocene successions exposed in a Wadi Gharandal can be interpreted using the integration of the lithologic characters and its foraminiferal association. Forty six agglutinated and seventy calcareous benthonic species has helped in segregate and distinguish six ecozones. Three transgressions (outer neritic to bathyal) and regressions (inner neritic and coastal) phases constitute three sedimentary cycles were recorded; the first transgression came with the deposition of the middle part of Mheiherrat Member; the second occurred during the deposition of the lower part of Hawara Member; while last one begins with the upper part of Asal Member. A great sea regression took place at the end of the Burdigalian forming an erosional surface, which represented by clastic sediments (sandstone lenses and pockets) and characterized by the absence of the microfaunal contents (foraminifera) followed by an anhydrite bed indicates a lagoonal environment for the lower part of Kareem Formation. The members of Rubies Formation are distinctively recognized and stratigraphically reconstructed based on its lithologic characters. Thirty-two planktonic foraminiferal species are also identified from the Aquitanian- Burdigalian successions that used to subdivide the studied rocks into three interval zoneszones (Globigerinoides primordius Zone; Globigerinoides altiaperturus Zone, Globigerinoides trilobus Zone) and one Barren Zone; these zones are correlated world wide with the standard international scheme of planktonic foraminiferal zoneszones and those recorded from neighboring areas.