Petrogenesis and Tectonic Implications of the Cryogenian I-Type Granodiorites from Gabgaba Terrane (NE Sudan)
Mabrouk Sami,
Munir M. A. Adam,
Xinbiao Lv,
El Saeed R. Lasheen,
Antoaneta Ene,
Hesham M. H. Zakaly,
Saad S. Alarifi,
Nasser M. Mahdy,
Abdel Rahman A. Abdel Rahman,
Adil Saeed,
Esam S. Farahat,
Douaa Fathy,
Shehata Ali
Affiliations
Mabrouk Sami
Geology Department, Faculty of Science, Minia University, El-Minia 61519, Egypt
Munir M. A. Adam
Faculty of Earth Resources, China University of Geosciences, Wuhan 430074, China
Xinbiao Lv
Faculty of Earth Resources, China University of Geosciences, Wuhan 430074, China
El Saeed R. Lasheen
Geology Department, Faculty of Science, Al-Azhar University, Cairo 11884, Egypt
Antoaneta Ene
INPOLDE Research Center, Department of Chemistry, Physics and Environment, Faculty of Sciences and Environment, Dunarea de Jos University of Galati, 800008 Galati, Romania
Hesham M. H. Zakaly
Institute of Physics and Technology, Ural Federal University, Yekaterinburg 620002, Russia
Saad S. Alarifi
Department of Geology and Geophysics, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia
The widely distributed granitic intrusions in the Nubian Shield can provide comprehensive data for understanding its crustal evolution. We present new bulk-rock geochemistry and isotopic (zircon U-Pb and Lu-Hf) data from the Haweit granodiorites in the Gabgaba Terrane (NE Sudan). The dated zircons presented a 206Pb/238U Concordia age of 718.5 ± 2.2 Ma, indicating that they crystallized during the Cryogenian. The granodiorites contain both biotite and amphibole as the main mafic constituents. The samples exhibit metaluminous (A/CNK = 0.84–0.94) and calc-alkaline signatures. Their mineralogical composition and remarkable low P2O5, Zr, Ce, and Nb concentrations confirm that they belong to I-type granites. They exhibit subduction-related magma geochemical characters such as enrichment in LILEs and LREEs and depletion in HFSEs and HREEs, with a low (La/Yb)N ratio (3.0–5.9) and apparent negative Nb anomaly. The positive Hf(t) values (+7.34 to +11.21) and young crustal model age (TDMC = 734–985 Ma) indicates a juvenile composition of the granodiorites. The data suggest that the Haweit granodiorites may have formed from partially melting a juvenile low-K mafic source. During subduction, the ascending asthenosphere melts might heat and partially melt the pre-existing lower crust mafic materials to generate the Haweit granodiorites in the middle segment of the Nubian Shield.
