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| Titel |
Deformation and metamorphism of Hamadat complex: Shear zones reshaping the lithosphere |
| VerfasserIn |
Mahmoud Hassan, Tamer Abu-Alam, Kurt Stüwe |
| 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 |
250112908
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| Publikation (Nr.) |
 EGU/EGU2015-15132.pdf |
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| Zusammenfassung |
| In the active tectonic regions, shear zones play an important role to re-configure the structure of the lithosphere. One of the largest pre-Mesozoic shear zones on the Earth is the Najd Fault System of the Arabian-Nubian Shield. Literature data record exhumation of medium-pressure metamorphic complexes due to the activity of the Najd Fault System during the Pan-African Orogeny where the shear zone surrounds the boundaries of metamorphic complexes. The Hamadat complex of Northwestern part of Saudi Arabia shows an exception where the metamorphic rocks appear to occur within the shear zone itself instead of being surrounded by branches of it. The Hamadat complex records peak metamorphic conditions of 505 - 700 ºC at two ranges of pressure 8 - 11 and 12.5 – 16.5 kbar. These pressures are higher than those of most other metamorphic complexes associated and exhumed by the Najd Fault system. The higher pressure conditions of the Hamadat complex relatively to other complexes in the shield can be interpreted in two different ways. The documented pressure can be due to lithostatic pressure or shear stress (i.e. in part non-lithostatic). Assuming the lithostatic condition, these pressure ranges indicate that the Hamadat complex consists rocks from two different crustal level (i.e. 28 - 38 km and 43 - 58 km) which shows the importance of the shear zone to reshape the lithosphere by bring rocks from different crustal level into one metamorphic complex. |
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