Abstract
A combined study of single zircon U-Pb dating, Hf-O zircon isotopic analyses and whole-rock Nd isotopic compositions was carried out to infer the magma sources of Neoproterozoic post-collisional A-type granitoids in Saudi Arabia. U-Pb zircon dating of magmatic zircons of two samples from the Hadb adh Dayheen ring complex yielded ages of 625±11Ma for a hornblende-biotite granite sample, and 613±4Ma for a monzogranite sample. The granitic rocks show initial εNd values of +4.1 to +5.3 and εHf of +4.5 to +8.4 that are lower than those of a model depleted mantle (εHf ~+14 and εNd ~+6.5) and consistent with melting of subduction-related crustal protoliths that were formed during the Neoproterozoic assembly of the Arabian-Nubian Shield (ANS). Crustal-model ages (Hf-tNC) of 0.81 to 1.1Ga are inconsistent with depleted-mantle Nd model ages of 0.71 to 0.81Ga and indicate that the post-collisional Hadb adh Dayheen granites were derived mostly from juvenile crust formed in Neoproterozoic time. Single zircons data show a wide range in δ18O values from +3.2‰ to +6.4‰, possibly indicating crystallization of zircon from magma derived from magmatic rocks altered by meteoric water in a magma chamber-caldera system.
Original language | English |
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Pages (from-to) | 348-360 |
Number of pages | 13 |
Journal | Lithos |
Volume | 206-207 |
Issue number | 1 |
DOIs | |
Publication status | Published - Oct 2014 |
Externally published | Yes |
Keywords
- A-type granites
- Arabian-Nubian Shield
- Single zircon Hf-O isotopes
- Sm-Nd isotopes
- U-Pb zircon dating
ASJC Scopus subject areas
- Geology
- Geochemistry and Petrology