Provenance of the heavy mineral-enriched alluvial deposits at the west coast of the Red Sea. Implications for evolution of Arabian–Nubian crust Munazzam Ali Mahar a,⇑ , Tarek M.M. Ibrahim b , Philip C. Goodell a a Department of Geological Sciences, University of Texas at El Paso, El Paso, USA b Nuclear Materials Authority, Cairo, Egypt article info Article history: Received 10 December 2013 Received in revised form 15 July 2014 Accepted 15 July 2014 Available online 12 August 2014 Keywords: Arabian–Nubian Shield Detrital zircon geochronology Magmatic evolution Alluvial fan deposits Provenance Juvenile Neoproterozoic crust abstract Here we present the LA-ICP-MS U–Pb ages and Hf isotopic record of detrital zircons from the active allu- vial fans at the west coast of the Red Sea. The Ras Manazal alluvial fan (primarily composed of zircon, magnetite with some rutile, ilmenite and monazite) yielded a relatively restricted age population ranges from 765 to 666 Ma. These ages and present-day drainage pattern is consistent that the sediments are primarily derived from erosion of nearby subduction related granitoids in the immediate west (i.e., not more than 50 km from the Red Sea coast) of the fan. In contrast, approximately 160 km south, at the Egypt–Sudan border, the Wadi Diit fan is relatively more enriched in ilmenite and REE-bearing phases (e.g., thorite, monazite, xenotime, garnet, etc.) and yielded five zircon age populations of (1) 824– 733 Ma, (2) 730–705 Ma, (3) 646–608 Ma, (4) 516–500 Ma, and (5) 134–114 Ma. The age populations 1–3 if coupled with the present-day drainage pattern can be related to the earlier subduction related and later post collision granitoids in the southern part of the South Eastern Desert and Gebeit terrane of northern Sudan. Sparse Early Cretaceous zircons (134–114 Ma) are derived from the Mesozoic volcanic suits in the source region. However, the age group 516–500 Ma is enigmatic. Wadi Diit zircons are pri- marily derived from granitoids in the broad S–N directed Hamisana Shear Zone and its subordinate SW to NE directed Onib-Sol-Hamed Suture Zone. These shear zones provided pathways for the pres- ent-day drainage system for sediment transportation to the Wadi Diit and adjacent coastal region. We infer that the ca. 500 Ma late-stage magmatic zircons represent a hitherto unknown magmatic event, possibly related to the shear heating associated with the crustal scale shear zones. This implies that the shear zones in the South Eastern Desert and northern Sudan remained thermally active as late as 500 Ma. The time resolved hafnium composition (eHf (t)) of both fans varies from +3.5 to +13.5. Our new U–Pb ages and Hf isotopic composition suggests that the detrital zircons were derived from the Neo- proterozoic juvenile crust. This is consistent with the Neoproterozoic juvenile igneous and metamorphic rocks in the Eastern Desert and northern Sudan. Ó 2014 Elsevier Ltd. All rights reserved. 1. Introduction The combined U–Pb and Hf isotopic record of detrital zircons provides insight regarding source region history of parental magma with which the zircon was in equilibrium at the time of crystalliza- tion. In the last two decades numerous studies have been devoted to the isotopic record of detrital zircons to establish detailed crustal evolution models (e.g., Griffin et al., 2006; Belousova et al., 2010; Kuznetsov et al., 2010; Matteini et al., 2010 and references therein) and sedimentary provenance interpretations (e.g., Koglin et al., 2010; Clements et al., 2012 and references therein). The Eastern Desert of Egypt is a part of the Neoproterozoic Ara- bian–Nubian Shield formed between 900 and 550 Ma by accretion of several mainly intra-oceanic arcs along ophiolitic sutures (Kröner, 1985; Stoeser and Camp, 1985; Vail, 1985; Johnson, 1998, 2014; Stern and Johnson, 2010; Ali et al., 2009, 2010a,b, 2012a; Johnson et al., 2011; Fritz et al., 2013)(Fig. 1). One of the longstanding controversies in this region is the origin of lower– middle crust beneath the Eastern Desert of Egypt forming the wes- tern part of the Arabian–Nubian Shield. Structurally lower granit- oid gneisses exhumed in the form of gneiss domes in the Eastern Desert are suggested to have a component of the older, pre-Neo- proterozoic crust that is pre-Pan-African basement (e.g., El-Gaby et al., 1984, 1988; Khudier et al., 2008). Many other workers sug- gested that the Arabian–Nubian crust is juvenile and exclusively Neoproterozoic in age formed in an intra-oceanic arc setting within http://dx.doi.org/10.1016/j.jafrearsci.2014.07.015 1464-343X/Ó 2014 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. E-mail address: mali3@miners.utep.edu (M.A. Mahar). Journal of African Earth Sciences 100 (2014) 510–523 Contents lists available at ScienceDirect Journal of African Earth Sciences journal homepage: www.elsevier.com/locate/jafrearsci