Magmatism and Related Mineralizations in Wadi Hammad, North Eastern Desert, Egypt

Abstract

Mineralization in the Wadi Hammad area is represented by polymetallic vein-type and occurs in four modes, they are mineralized main quartz vein, silicified shear zone, associated hydrothermal alterations, and breccia zones. They mainly occur in the contact between Dokhanvolcanics and Younger granites and are confined to and controlled by the Wadi Hammad shear zone. The study revealed that Dokhan volcanics have adakitic nature and are formed by slab melt. Accordingly, these rocks are favorable sites for the formation of Au-(Cu)deposits. Hammad granite rocks are characterized bymetaluminous to weakly peraluminous, span the boundary between the ilmenite-magnetite series, transitional between moderately and strongly oxidized granites, situated a relatively shallow to moderate depths (20 to 30 km), and started to crystallize at temperatures around 800 °C. It is suggested that mineralization in WadiHammad formed due to intrusion of the strongly oxidizing, water-and volatile-rich, and alkaline to alkaliecalcic magma into the adakiticDokhan volcanic leads to circulation of these fluids in the latter leaching the available metals (Au and base metals). The leached metals are deposited in preexisting open fissures at the cold end of convective cells near the surface form Au (Cu)-rich quartz veins.

Overview of Circular Structures of Various Origins and Sizes in Egypt as a Contribution to Natural Hazard Data Mining Based on Remote Sensing Data and Geoinformation Systems (GIS) Analysis

“…Several hundred of the magmatic intrusions along the Red Hills were emplaced at the end of the Pan-African orogeny and the opening of the Red Sea Rift [16]. The close of the Pan-African orogeny was characterized by a change from subduction and arc-related magmatism to post-tectonic alkaline magmatism [17] comprising the emplacement of the calc-alkaline and alkaline granites at (610-590 Ma). The ring complexes can be related to swells or arches in the crust essentially distributed at random, but with some alignment along lines of weakness which might have partly existed since Precambrian times and suffered frequent rejuvenation [6].…”

“…Figure 18 shows an example of a crater with a central plug in the southern Red Hills cutting through dike swarms. Miocene magmatism, obviously linked with the opening of the Red Sea[17], resulted in surface eruptions and subsurface magmatic intrusions. In comparison with the previously shown areas in SW-Egypt, there are fewer traces of volcanic explosive activity in SE-Egypt.…”