After Khalil and Helba

The Hangalia granite is situated at the most northern part of the Gebel Nugrus pluton, which is emplaced within a sequence of ophiolitic rocks (comprising metavolcanics, metasediments, serpentinites and metagabbrodiorite rocks) and postdated the suturing and the earlier transition of the Pan-African mobile belt of North-East Africa from oceanic to continental crust is Late Precambrian time.

The Nugrus pluton has sharp intrusive contacts with the surrounding basements rocks in the area and is nearly parallel to the major low angle “Nugrus thrust”.

At the Hangalia mine area, the pink biotite granite (the so called Hangalia granite) and the metagrabbrro-diorite complex are the host rocks for the auriferous quartz veins. The granite belongs to the late- to post-oroginic category (synonym to Younger Granite) which is generally emplaced between 620-530 Ma.

The least altered granite variety is medium-grained and is composed mainly of quartz, alkali and plagioclase feldspars with minor biotite. The rock is porphyritic with some perthitic phenoocrysts embedded in a granophyric groundmass reflecting shallow depth of emplacement.

The metagabbro-diorite complex represents the oldest rock unit in the area. It represents with the overlain metavolcanics the Early Pan-African volcanic rocks with an age of 950-750 Ma. The metagabbro-diorite complex at the Hangaliya gold mine area is composed essentially of plagioclase (andesite and labradorite) and amphibole.