Abstract
Um Taghir area is located in the northern extreme boundary of Central Eastern Desert of Egypt at the west of Safaga City. Um Taghir is represented by island arc related rocks and late to post tectonic magmatism. The island arc related rocks are represented by metavolcaniclastic sequences and metagabrroic rocks. Metavolcanoclastic rocks are considered as the older rock units of the study are and intruded by the metagabbro. The late to post tectonic magmatism is represented by (dokhan volcanic, gabbro, tonalite-granodiorite, monzogranite, alkali feldspar granites and different types of dikes). Usually, the gabbroic rock is bearing ilmenite lenses or bands in the bottom of the layered; this is related to magma rich of iron oxides. Petrographically, island arc assemblage is classified in to actinolite hornblende schist and metagabbro that show quite different of their content in plagioclase, hornblende, augite, quartz and biotite. Occasionally, the late to post tectonic magmatism represented by andesite, gabbro, tonalite, granodiorite monzogranite, alkali feldspar granites and different types of dikes. Andesite consists of plagioclase, quartz, alkali feldspar and hornblende. Gabbroic rocks are represented by pyroxene hornblende gabbro and leucogabbro. They show quite different of their content in plagioclase, pyroxene and clear difference in the content of both olivine and hornblende in both of them. While tonalite and granodiorite show quite different of their content in plagioclase, quartz, hornblende, alkali felspar and biotite. On the other hand, monzogranite and alkali feldspar granite, they show plagioclase is varying from oligoclase to albite; K-feldspars, quartz and muscovite are relatively more abundant in the alkali feldspar granite. Finally, the different types of dikes classified into granite, andesite, rhyolite and basalt dikes consist of the different mineral compositions.
Highlights
Um Taghir area is located in the northern extreme boundary of Central Eastern Desert of Egypt at the west of Safaga City (Fig. 1)
The exposed different rock units of the study area belong to the Northern part of the Arabian-Nubian Shield (ANS) that began at ~870 Ma and established at ~620 Ma ago, when convergence between east and west Gondwana fragments closed the Mozambique ocean along the East African-Antarctic Orogen (EAAO)
Um Taghir area is located in the Central Eastern Desert of Egypt on the Qena–Safaga road
Summary
These rocks are related to the western arc or oceanic terrains of ANS that collided and amalgamated between 680 and 640 Ma creating a new continental crustal block referred to as the proto-Arabian-Nubian Shield (pANS), (Johnson et al, 2011). It is characterized by medium to coarse – grained massive rocks, dark grayish to dark greenish color, not layered, highly fractured and deformed, sometimes smooth, generally one set of joints with predominant striking to 235° with vertical dipping to show well developed blocky structure, occasionally, shows spheroid shape (union shape) due to the weathering and exfoliation (Fig. 3, d), generally, unlayered gabbro intruded directly by granodiorite and monzo-
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