Influence of the alteration processes on the origin of uranium and europium anomalies in trachyte, central Eastern Desert, Egypt

Role of geochemical alteration on the formation of secondary Zr- and U-bearing minerals in El Atshan trachyte, central Eastern Desert, Egypt

“…This tectonic event is probably related to the late Pan -African tectono -thermal event that involves PermoTriassic magmatism, the Late Jurassic -Early Cretaceous hydrothermal phase, Late Cretaceous -Early Tertiary hydrothermal phase, and the Tertiary volcanicity and OligoMiocene phase (Dawood et al, 2004). The occurrence of Figure 7.…”

“…The geology of the El Atshan area has been investigated by Obrenovic et al (1966), Hussein and El Kassas (1972), Osmond et al (1999), and Dawood et al (2004). The main rock units are (from older to younger) metasediments, metavolcanics, Hammamat sediments, granites, and post -tectonic volcanics (Fig.…”

“…The trachyte is sheared and brecciated in some parts; the resulting fractures are filled with uranium minerals deposited from solutions. Dawood et al (2004) studied the geochemistry of the trachyte in the study area. They concluded that this rock was subjected to two phases of alteration.…”

“…These rocks have previously been recognized as bostonite (El Hazek, 1968;Attawiya, 1971;Hussein and El Kassas, 1972). Recently, Dawood et al (2004) classified these rocks as trachyte on the basis of their geochemical characteristics. However, the term trachyte is used in the present study that refers to the mineralized volcanic rock in El Atshan area.…”

“…The secondary uranium minerals are represented by uranophane, kasolite, soddyite, gummite, schoepite, schroeckingerite, rutherfordine, zippeite, and uranopilite (Attawiya, 1971). However, only soddyite, kasolite, and uranophane have been confirmed to be present in El Atshan (e.g., Osmond et al, 1999;Dawood et al, 2004).…”