Facies, Geochemistry and Rare Elements Potentiality of Um Bogma Formation in the Area East of Wadi Baba, Southwestern Sinai, Egypt

Abstract

The Paleozoic succession in southwestern Sinai overlies the Precambrain Basement Complex. This succession consists of the formations (from older to younger): Sarabit El-Khadim, Abu Hamata, Adediya, Um Bogma and Abu Thora. The mineralized Lower Carboniferous Um Bogma Formation was studied in eight localities distributed in a vast area east of Wadi Baba wherein its exposures are relatively well developed. These localities are (from west to east) Talet Seliem, Abu Zarab, Abu Thor, Farsh Al- Azraq, Allouga, Lehyan, Wadi Sewig and Ramlet Himeyir. Extensive field studies on the Um Bogma Formation in these localities comprised the construction of geologic maps, the collection of a large number of spot and channel samples as well as carrying out radioactive field measurements. The formation in the study area consists of three distinct members showing marked lateral variations in thickness and lithology. Throughout the study area, the lower member is made up of siltstone, sandstone, dolostone, dolomitic limestone, siltstone- hosting Fe- sulfides and siltstone and sandstone hosting Fe- Mn ore. The middle member consists of shale, claystone, mudstone, siltstone, sandstone, conglomerate, dolostone and dolomitic limestone. The upper member is made up of dolostone, dolomitic limestone, sandstone and conglomerate. Geographically, the lower member of Um Bogma Formation is composed mainly of argillaceous rocks interbedded with some carbonates in the western, central and southern sectors of the study area and argillaceous rocks in its eastern sector. The middle member is made up of interbeds of siltstone, claystone, dolostone and conglomerate in the most western sector of the area, siltstones and mudstone