Zircon geochronology and Sr, Nd, Pb isotope geochemistry of granitoids from Bayuda Desert and Sabaloka (Sudan): evidence for a Bayudian event (920-900 Ma) preceding the Pan-African orogenic cycle (860 - 590 Ma) at the eastern boundary of the Saharan Metac
View/ Open
Discipline
Earth and related Environmental sciences
Subject
Geodynamics and mineral resources
Audience
Scientific
Date
2008Publisher
Elsevier
Metadata
Show full item recordDescription
Results of zircon geochronology and Sr, Nd and Pb isotope investigations carried out on granitoid rocks from the boundary of the Saharan Metacraton with the Arabian-Nubian Shield (ANS) reveal a protracted, partly pre-Pan-African geodynamic evolution and the existence of crustal terranes of different ancestries. (Meta)granitoids and gneisses in north-central Bayuda Desert record a 920-900Ma orogenic event, hitherto unrecognized in northeastern Africa. This early Neoproterozoic Bayudian event is restricted to a pre-Pan-African crustal terrane which appears only slightly affected by Pan-African tectogenesis and deformation, named here the Rahaba-Absol terrane. Within this terrane, amphibolite-facies metamorphism occurred at 921±10Ma in the El Melagi muscovite-biotite gneiss of the Rahaba Series, probably during a collisional phase; followed by the intrusion of the Absol medium-K granite-granodiorite pluton discordantly emplaced at 900±9Ma into high-grade schists and amphibolites of the metavolcanosedimentary Absol Series. Nd TDM model ages (2040-2430 Ma) and ages of rounded zircon cores (1060, 1980, 2540 and 2675 Ma) of the El Melagi gneiss indicate a predominantly late Archaean to Palaeoproterozoic source region and suggest a latest Mesoproterozoic to early Neoproterozoic depositional age of its pelitic precursor sediment. The post-collisional Absol pluton has isotope characteristics (Nd-Sr-Pb) indicating assimilation of old pre-Neoproterozoic crust. The Rahaba-Absol terrane is part of the Saharan Metacraton and is in tectonic contact with the high-grade metamorphic Kurmut terrane of eastern Bayuda Desert. The Kurmut terrane has juvenile Neoproterozoic isotope characteristics, its granitoids record only Pan-African orogenic events and it is therefore considered a part of the Arabian-Nubian Shield. Both the Rahaba-Absol and the Kurmut terrane of the Bayuda Desert are intruded by post-collisional high-K granitoid magmatism of late Pan-African age, with no intermediate events recorded.
Citation
Küster, D; Liégeois, J.P.; Matukov, D; Sergeev, S; Lucassen, F (2008). Zircon geochronology and Sr, Nd, Pb isotope geochemistry of granitoids from Bayuda Desert and Sabaloka (Sudan): evidence for a Bayudian event (920-900 Ma) preceding the Pan-African orogenic cycle (860 - 590 Ma) at the eastern boundary of the Saharan Metac. , Precambrian Research, Vol. 164, 16-39, Elsevier, DOI: 10.1016/j.precamres.2008.03.003.Identifiers
Type
Article
Peer-Review
Yes
Language
eng