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| Titel |
Arabian-Nubian Shield: incomplete vision and opened questions |
| VerfasserIn |
Mahmoud Hassan, Saad Al Garni, Adeeb Al Hussaini, Mubarak Alnahdi, Abdullah Al Shammari, Tamer Abu-Alam |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250112329
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| Publikation (Nr.) |
 EGU/EGU2015-15134.pdf |
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| Zusammenfassung |
| The Arabian-Nubian Shield is a juvenile crust formed during the Pan-African Orozgeny due the closure of the Mozambican ocean as a result of East- and West-Gondwanaland collision. The shield records part of Earth’s history of about 300 Myr. The formation of the shield is close related to the activity of the major pre-Mesozoic shear zone on the Earth – the Najd Fault System. The Najd Fault System exhumed several metamorphic complexes in different setting; some of them were exhumed in extension setting as metamorphic core complexes, others were exhumed in compressional setting or in oblique compression setting as strike-slip complexes. The metamorphic complexes represent middle crustal level rocks (25 – 50 km depth) exhumed to a shallower level (of about 14 km depth). At the depth of 14 km the shield was intruded by syn-tectonic granitic suites known as older granites. These metamorphic complexes have an acidic composition in contrast to the average basic composition of the shield. Detrital-zircon geochronological data from Nubian sandstone indicate that the metamorphic complexes exhumed completely to the Earth’s surface by the end of the Pan-African orogeny.
There are some open questions still need to be addressed to complete our vision of the shield. Some of these questions are: What are the protoliths of the metamorohic complexes? These protoliths are juvenile rocks formed during the Pan-African orogeny and have acidic composition but no information available about the origin, the tectonic setting or the formation mechanism of these rocks. What is the relation between the exhumation of the metamorphic complexes to a crustal level of about 14 km and the intrusion of the syn-tectonic granites to the same crustal level. How did the metamorphic complexes exhumed to the Earth’s surface by the end of the Pan-African orogeny? |
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