[On the] geochemistry and mineral chemistry of the Gabbroic rocks at Wadi Um Khors area, central eastern desert, Egypt

The studied metagabbro-diorite complex comprises hornblende metagabbro, quartz-metagabbro, appinitic-metagabbro, and quartz diorite beside the fresh gabbro relics. They are calc-alkaline and were emplaced at subduction zones related to island arc magma. They were subjected to metamorphism but still carry minor relics of fresh gabbro. Mineralogically, the metagabbroic rocks are composed of plagioclase [An 30-45], Ca-rich clinopyroxenes [diopside and augite] and hornblende of green and olive brown colour]. The obtained crystallization temperature for the coexisting plagioclase- olive brown hornblende mineral pair was 600 - 700 °C and for the coexisting plagioclase- green hornblende mineral pair was 800 - 900 °C. The Ca-rich clinopyroxenes are low in alumina content suggesting crystallization between 500 and 1100 °C at shallow depth. Also, the analyzed clinopyroxenes pertain to those found in sub- alkaline rocks. The studied metagabbroic rocks show relative enrichments in LILE [Sr, Rb, Ba] over the HFSE [Nb, Zr, Y], a feature characteristic of subduction- related magmas