Ultramafic Rocks and Their Alteration Products From Northwestern Allaqi Province, Southeastern Desert, Egypt: Petrology, Mineralogy, and Geochemistry

Abstract

The ophiolitic rocks, island arc metasediments, and granitic rocks are encountered in the study of the Allaqi province. The present study concentrated on ultramafic rocks and their various forms of hydrothermal alteration. Ophiolites commonly occur as dismembered rock sequences and have different types of hydrothermal alteration products. Ophiolites contain the essential type as serpentinites and talc-carbonate rocks, listwaenites, and amphibolites along shear zones and faults. Listwaenite is one of the most significant rocks in this area because it contains gold. The whole serpentinite rocks are affected by regional metamorphosis into greenschist facies. Geochemically, Neoproterozoic serpentinites fall into SSZ ophiolites, alpine-type peridotite, formed in the forearc peridotite tectonic environment. Regardless, the listwaenite and talc-carbonate rocks revealed that they trend to silica, carbonate, and talc. Listwaenites are classified into two types: carbonate-rich listwaenites and silica–carbonate-rich listwaenites. Magnetite, chromite, galena, and gold are the most typical ores recorded in this research.

Distribution, speciation, and assessment of heavy metals in sediments from Wadi Asal, Red Sea, Egypt

“…The major content of Ni is hosted in the residual fraction (ranging from 40.16 to 64.52%) of Wadi Asal sediments. It confirms their natural geogenic origin due to the provenance of the Egyptian basement complex rocks (Reimann & de Caritat, 1998 ; NPI, 2012 ; Abdel-Rahman et al, 2022 ). Thus, it is challenging to remove Ni from this fraction.…”

Notable changes in geochemical and mineralogical characteristics of different phases of episyenitization: insights on the radioactive and shielding of the late phase

“…Each alteration introduces specific minerals and elements, which can alter the granite's properties, including its density and capacity for radiation attenuation (Zakaly et al, 2022;2023). Moreover, the presence of mineral deposits, particularly those containing precious and base metals, is often associated with the hydrothermal alteration processes in these acidic rocks (El-Mezayen et al, 2015;Tarrah, 2016;Watanabe et al, 2018;Abdel-Rahman et al, 2022;Awad et al, 2022b;Taalab et al, 2023).…”