Geology, petrology and geochronology of the metamorphic rocks of Meatiq Dome, Central Eastern Desert, Egypt
Meatiq Dome is an antiformal structure exposed in a 500 sq km area in the Late Proterozoic terrane of the Central Eastern Desert of Egypt. The dome consists of a conformable sequence of metamorphic units. In ascending order, these are granite gneiss, quartzofeldpathic mylonite, quartz phyllonite, and mafic mylonite. Syntectonic intrusions of diorite tonalite granodiorite are within the units above the granite gneiss. Post tectonic granite crosscuts all other units. Foliation in the metamorphic units is low angle, and is associated with NW trending lineation, intrafolial folds have axes subparallel to lineation. The granite gneiss consists of two subunits--one (white gneiss) is marginally peralkaline and arfvedsonite bearing, and the other (pink gneiss) is metaluminous and hornblende and biotite bearing. The quartzofeldspathic mylonite is nearly identical in composition to the pink gneiss, compatible with a single granite protolith for these two units. The quartz phyllonite bears strong compositional resemblance to the pink gneiss and quartzofeldspathic mylonite, with the main exception of Na content which is very low in this unit. The chemical data suggest that the quartz phyllonite had a volcanic protolith that had undergone extensive hydrothermal alteration soon after emplacement.
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- Metamorphic Rocks;
- Fissures (Geology);