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Repeated magmatic pulses in the East African Orogen in the Eastern Desert, Egypt: An old idea supported by new evidence

Research Authors
Anders Mattias Lundmark , Arild Andresen , Mohamed A. Hassan b, Lars Eivind Augland , Gamal Yehia Boghdady
Research Abstract

This paper presents U–Pb ID-TIMS geochronological data from granitoids in the Hafafit area in the Central and
South Eastern Desert, Egypt. It dates several Neoproterozoic magmatic pulses and metamorphic events, and
constrains one episode of U, Nb and Ta mineralisation along the Nugrus Shear Zone, part of the Eastern Desert
Shear Zone, to 608±1 Ma. The data testify to the localized nature of deformation in the Eastern Desert, illustrating
that previous subdivisions of granitoids into “Older” and “Younger” based on field criteria are inadequate.
With robust ages fromgranitoids in theMeatiq, El Sibai and El Shalul areas the newages indicate 6 pulses of magmatism
and/or metamorphism at (1) 705–680, (2) c. 660, (3) 635–630, (4) 610–604, (5) 600–590 and (6) c.
540 Ma. Most pulses are defined by ages from granitoids in both gneiss windows/domes and in the overlying
eugeoclinal allochthon; the two tiers represent different crustal levels of related rocks. We propose that pulses
1–3 are syn-orogenic, pulses 4 and 5 reflect exhumation of mid-crustal gneisses along the Eastern Desert
Shear Zone, whereas the final pulse post-dates the East African orogeny. Based on available data we propose
that the tectono-magmatic evolution above applies to the entire Eastern Desert.

Research Department
Research Journal
Gondwana Research
Research Rank
1
Research Vol
Vol.22
Research Year
2012
Research Pages
PP.227–237