Um Adawi Granites

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The Um Adawi Granites are granitic igneous rock formations found in the southeastern Sinai Peninsula. Um Adawi granitic rocks have field relations, petrographic and chemical characteristics similar to the older granites of the Eastern Desert and the Arabian Shield. They have a batholitic dimension and occur as composite plutons intruding the metasediments and the metavolcanics, while the younger granites intrude them. Petrographically, the rocks are homogeneous, light to dark grey and medium- to coarse-grained. They comprise quartz monzodiorite, tonalite and granodiorite. Plagioclase (An21-32), quartz, k-feldspar, hornblende and biotite represent the essential minerals. Accessory minerals are apatite, sphene and opaques. Whole rock and mineral chemistry explained that the Um Adawi older granites are calc-alkaline with metaluminous signature. They were emplaced in a compressional regime in an arc tectonic setting inside a crust of about 30km thickness. The rare earth patterns of studied granites suggest that they are subduction related supporting the obtained magmatic affinity and the tectonic setting.

[edit] References

M. G. Shahien and Obeid, M. A.,2002, Geochemistry and Petrogenesis of the Early-orogenic Older Granites at the Um Adawi Area, Southeastern Sinai, Egypt. Egypt. J. Geol.,