Calcareous microfossils, depositional environments and correlation of the Lower Carboniferous Um Bogma Formation at Gebel Nukhul, Sinai, Egypt

Publisher Website
Google Scholar
Abstract
The Um Bogma Formation represents a short-lived, open marine incursion into the continental-paralic environments predominant in the Gulf of Suez region during the Paleozoic. At Gebel Nukhul the formation consists of upper and lower sandy dolomite members and a middle member of interbedded calcareous shale, sandy dolomite and sandy dolomitic limestone. The middle member contains numerous calcareous foraminifers, algae ? and incertae sedis that correlate to the early middle Visean in northwestern Europe and approximately to the late Osagean-early Meramecian in North America. The assemblage is fully illustrated and selected taxa are described, including the new foraminiferal species Uralodiscus adindanii. Clastic marine sediments began covering the Precambrian basement at Gebel Nukhul in Early Carboniferous time. This transgression culminated in the deposition of the Um Bogma carbonates, which represent the maximum advance of the Lower Carboniferous sea into west-central Sinai. The diversity and abundance of fossils throughout the formation, as well as the paleogeographic setting, suggest deposition within a normal marine cycle. Dolomitization of the lower and upper members probably resulted from hydrothermal alteration associated with Tertiary tectonism. Apparently the presence of shales within the middle member prevented dolomitization of some of the intercalated limestones and thus preserved the calcareous microfossils.

This publication has 2 references indexed in Scilit: