T198 Radiogenic Isotopes as Tracers of Geologic Processes: Dates, Rates, and Proxies (Posters)

Tuesday, 11 October 2022
2:00 PM - 6:00 PM
Exhibit Hall F

ROLE OF THE JUVENILE VERSES REWORKED CONTINENTAL CRUST IN THE GENERATION OF THE ARABIAN-NUBIAN SHIELD: INSIGHTS FROM U-PB GEOCHRONOLOGY, HF ISOTOPIC AND TRACE ELEMENT COMPOSITION OF DETRITAL ZIRCONS FROM THE EASTERN COAST OF THE RED SEA, KINGDOM OF SAUDI ARABIA

Paper number: T198-3
Program: Technical Sessions
Time: 2:00 PM – 6:00 PM

Authors

Abstract

This study reports the U-Pb ages, Hf isotopic composition and trace element chemistry of detrital zircons extracted from four composite beach sand samples from the eastern coast of the Red Sea. U-Pb data identified three age populations, including Ediacaran (540 - 635 Ma), Cryogenian (640-720 Ma) and Tonian (720 - 1000 Ma). Inherited and xenocrystic zircons yielded Neoproterozoic dates ranging from 1400 - 1000 Ma and much older Paleoproterozoic and Archean dates ranging from 3.1 -1.8 Ga. The Ediacaran zircons ranging in age from 629 to 587 Ma yielded individual radiogenic but enriched εHf (t) values (i.e., below the depleted mantle curve) vary from +6 to +10.9. The εHf (t) of the depleted mantle during the Ediacaran is +14 ± 1. While Cryogenian zircons (725-663 Ma) yielded elevated and depleted εHf (t) values range from +10.1 to +13.7. Few Tonian zircons yielded near-chondritic εHf (t) composition of 0 ± 2.5. Neoproterozoic zircons (1048-1012Ma) generally yielded chondritic to nonradiogenic εHf (t) composition with a maximum of -13.8. Two Paleoproterozoic zircons dated at 2.03 and 1.8 Ga yielded εHf (t) composition of -0.9 and -10.7, respectively. Zircon trace element chemistry coupled with age data and Hf isotopic composition suggest that the Cryogenian zircons are related to the intra-oceanic subduction-related magmatic rocks produced by the fractionation of the sublithospheric mantle-derived sources. In contrast, the enriched Ediacaran zircons can be related to the post-collision magmatic rocks produced by the partial melting of a distinct and enriched mantle reservoir formed during the earlier Crygenian-Tonian arc development. However, the presence of Neo- as well as Paleoproterozoic with some Archean zircons suggest that in addition to the mantle-derived sources, contribution of older crustal sources may not be ruled out.

Geological Society of America Abstracts with Programs. Vol. 54, No. 6

doi: 10.1130/abs/2022AM-382087

© Copyright 2022 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.