Age of Betain Gneiss; implication for Late Precambrian crustal evolution in Souteastem Desert, Egypt
The gneiss-migmatite rocks pf Hodein area, which represents the southeastern extension of Beitan Gneisses, cover about 98 km and trend NW-SE. These rocks are overthrusted by supracrustal cover mainly arc-ophiolite assemblage and granitic rocks. Petrologically, the rocks are divided into biotite-gnei...
Elmentve itt :
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| Dokumentumtípus: | Cikk |
| Megjelent: |
University of Szeged, Department of Mineralogy, Geochemistry and Petrology
Szeged
1993
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| Sorozat: | Acta mineralogica-petrographica
34 |
| Kulcsszavak: | Kőzettan, Ásványtan, Földtan, Geokémia |
| Tárgyszavak: | |
| Online Access: | http://acta.bibl.u-szeged.hu/24808 |
| Tartalmi kivonat: | The gneiss-migmatite rocks pf Hodein area, which represents the southeastern extension of Beitan Gneisses, cover about 98 km and trend NW-SE. These rocks are overthrusted by supracrustal cover mainly arc-ophiolite assemblage and granitic rocks. Petrologically, the rocks are divided into biotite-gneisses, hornblende-gneisses, biotite-hornblende-gneisses, gamet-biotite-hornblende-gneisses ana augen-biotite-gneisses. The whole rock Sm-Nd isochron age of the Beitan gneisses yield 889±8 Ma (MSWD=8.5) which is consistent with Rb-Sr age (863±15 Ma, MSWD=9). This rock has initial £Nd and e'sr-values (-8.6 and +9.5, respectively) which reveals the age of early Pan-African. Moreover, the Nd-model age (TDM) of these rocks range from 1.46 to 2.65 Ga, negative ElNd and low e'sr-values reveal the existence of early Pan-African continental crust. The data are tested against mantlecrust mixing model. It is suggested that these rocks were derived throughout assimilation of about 35—50% Nd-enriched, sligntly Sr-depleted lower crust component by a mildly depleted subcontinental mantle source. |
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| Terjedelem/Fizikai jellemzők: | 41-50 |
| ISSN: | 0365-8066 |