Hf isotopic composition of single zircons from Neoproterozoic arc volcanics and post-collision granites, Eastern Desert of Egypt: Implications for crustal growth and recycling in the Arabian-Nubian Shield

Kamal A. Ali, Simon A. Wilde, Robert J. Stern, Abdel Kader M. Moghazi, S. M.Mahbubul Ameen

Research output: Contribution to journalArticlepeer-review

66 Citations (Scopus)

Abstract

Zircon Hf isotopic compositions for Neoproterozoic igneous rocks in the Central Eastern Desert of Egypt are presented and interpreted. The Humr Akarim (633±7 and 603±9Ma)-Humrat Mukbid (625±8 and 619±8Ma) plutons are Early Ediacaran post-collsional subsolvus granites. Their zircon ages range from 0.57 to 0.71Ga, with high positive e{open}Hf(T) values of +4.0 to +11.9. Hf model ages (Hf-TDMc) of 0.81-1.3Ga, are close to the U-Pb crystallization ages. These isotopic characteristics, along with published whole-rock Nd isotopic data, indicate that the protoliths were juvenile. The Wadi Kareim and Wadi El-Dabbah metavolcano-sedimentary rocks are Cryogenian (~750Ma) arc-related metabasalts, meta-andesites and meta-tuffs. Their U-Pb zircon age populations range between 0.7-0.9, 0.9-1.5Ga and 2.0-3.0Ga. The youngest group represents magmatic zircons in the metavolcanics or reworked Neoproterozoic rocks in the metasediments. The 0.9-1.5Ga and 2.0-3.0Ga age groups are similar to those in pre-Neoproterozoic rocks that surround the Arabian-Nubian Shield and represent inherited or older detrital grains. The highly variable e{open}Hf(T) values (+23.5 to -35.0) and Hf-TDMc ages (0.78-3.8Ga) of Neoproterozoic zircons indicate that at least some of these magmas interacted with a pre-Neoproterozoic crustal source.

Original languageEnglish
Pages (from-to)42-55
Number of pages14
JournalPrecambrian Research
Volume239
DOIs
Publication statusPublished - Dec 2013
Externally publishedYes

Keywords

  • Arabian-Nubian Shield
  • Egypt
  • Hf-isotopes
  • Neoproterozoic crust
  • Single-zircon Hf-isotopes

ASJC Scopus subject areas

  • Geology
  • Geochemistry and Petrology

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