The present manuscript aims to infer environments of deposition, provenance, maturity, paleoclimate and tectonic setting of the thick Paleozoic–Lower Mesozoic sedimentary succession at Um Bogma area, southwestern Sinai, Egypt. This has been performed via facies analysis, petrography, mineralogy, and geochemistry of five siliciclastic-dominated rock units (Araba, Abu Thora, Abu Durba, Qiseib, and Temmariya formations). Eight siliciclastic lithofacies have been identified and related to low sinuosity braided channel, meandering fluviatile, overbank, flood plain, crevasse splay, coastal plain tidal flat, and intertidal to shallow subtidal environments. Microscopically, the rudaceous–arenaceous rocks are belonged to oligomictic–polymictic conglomerate, quartzarenite, and subarkose–arkose microfacies. The argillaceous rocks are represented by shale, Fe-shale, and black shale and consist of illite, kaolinite, and subordinate amount of illite/smectite mixed layer. Geochemically, the studied sandstones exhibit moderate to high silica content that increases from clay-rich sandstones of the Araba Formation to those (clay-poor) in the Abu Thora and Abu Durba formations on the expense of Na2O, Ka2O, and Al2O3 contents. Plotting of the major oxides revealed a felsic igneous provenance source for the studied sandstones of the whole succession with additional intermediate igneous source for those of the Araba Formation. In terms of tectonic setting, different discriminating diagrams revealed a passive continental marginal basin for the studied sediments. The chemical indices of the studied sediments reflect variable degrees of palo-weathering of precursors. High maturity and predominance of kaolinite in the studied sandstones of the Abu Thora and Temmariya formations reflect a humid climate, while the studied sandstones of the Araba, Abu Durba, and Qiseib formations are characterized by a low maturity with abundance of illite reflecting a dominance of arid climate. |
