Geochemical typology and origin of the granitoid rocks of Wadi Akhdar, Central-South Sinai

The granitoid rocks of Wadi Akhdar area are represented by comagmatic granodiorite, hornblende and biotite granites and biotite monzogranites. Mafic xenoliths and microxenoliths are relatively more abundant in the mafic granitoids. Variations within the granitoids reflect the degrees of separation o...

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Bibliographic Details
Main Authors: Soliman F. A.
Hassen Imbarak Sayed
Format: Article
Published: University of Szeged, Department of Mineralogy, Geochemistry and Petrology Szeged 1999
Series:Acta mineralogica-petrographica 40
Kulcsszavak:Kőzettan, Ásványtan, Földtan
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Online Access:http://acta.bibl.u-szeged.hu/24882
Description
Summary:The granitoid rocks of Wadi Akhdar area are represented by comagmatic granodiorite, hornblende and biotite granites and biotite monzogranites. Mafic xenoliths and microxenoliths are relatively more abundant in the mafic granitoids. Variations within the granitoids reflect the degrees of separation of restites from the melt produced during fusion event. Geochemically; the Akhdar granites show calc-alkaline affinity and they have similar ranges for alumina balance, alkali ratio, alkali/calcium ratio, normative feldspar, and trace elements distribution. They show remarkably similar degrees of differentation and tectonic setting (volcanic arc granites"VAG", and orogenic granites type "OGT"). Geochronologically; in accordance with field relationships, the emplacement of the Akhdar granites has taken place almost simultaneously and at least three phases of granite magmatism are recognized. The syn-collision granodiorite (older phase of granite magmatism), is deeply eroded, melanocratic and it ranges from mild metaaluminous to peraluminous, and it is poorly to moderately differentiated. In contrast, the younger phase of granite magmatism has been produced strongly differentiated melanocratic biotite-bearing granites. Based on the obtained petrographic and geochemical data the magmas of the Akhdar pluton have been formed at 700-850 "C temperature and under 6-8 Kb. pressure. Probable petrogenesis of Akhdar granitoids should involve partial melting of meta-igneous rocks and fractional crystallization of the produced melts.
Physical Description:105-120
ISSN:0365-8066