Ediacaran (similar to 600 Ma) orogenic gold in Egypt: age of the Atalla gold mineralization and its geological significance

摘要

Integration of a new monazite U-Pb age for the Atalla monzogranite (615 +/- 9 Ma) and a Ar-40/Ar-39 plateau age of hydrothermal white mica (601 +/- 5.5 Ma, 2 sigma) disseminated in gold-bearing quartz veins at the Atalla mine indicates post-intrusion Au-mineralization, overlapping with cooling and regional exhumation ages of the Central Eastern Desert. The mica age is in agreement with published Re-Os age of gold mineralization in the Fawakhir area, similar to 20 km to the south along the Atalla shear zone. The new geochronological data demonstrate lode gold formation during the similar to 600 Ma period, controlled by wrench tectonics along Najd-related structures in the region (620-585 Ma). Fluid focusing and gold deposition during the Ediacaran were promoted by contrasting lithological and rheological properties at the granite-ophiolites contacts. This seems to be a typical setting for gold ores in this part of the Nubian Shield, and can aid exploration for undiscovered resources in the region.