Petrogenesis of granitoid rocks of Wadi Baba Area southern Sinai-Egypt

Abstract EN

The granitoid rocks, in the Wadi Baba area have been classified according to the field relations, petrographieal, and geochemical studies into syn-orogenic granitoids comprising, monzodiorite, tonalile, and granodiorite varieties and post-orogenic granites including the mon-zogranite; syanogranite and alkali-feldspar granite varieties.

These granitoids intrude the neighbouring dioritic rocks with sharp contacts.

Geochemical studies indicate that, the syn- and post-orogenic granitoids are not related lo the dioritic rocks, but, are genetically related to each other.

Both syn- and post-orogenic granitic intrusions are peraluminous and calc-alkaline, with the post-orogenic granites showing alkaline nature.

The syn-orogenic granitoids have most of the features associated with the I-type granites and are formed over a subduction zone through partial melting of a mantle wedge with little crustal melt contribution.

The post-orogenic granites have most of the features associated with S-type granites and are formed through partial melting of the crustal rocks with little contribution from the mantle (or by mobilization of older granitoids) under compression in the lower levels of a thickened crust.