Article ID Journal Published Year Pages File Type
4715957 Lithos 2014 13 Pages PDF
Abstract

•Hadb adh Dayheen granitic rocks are Neoproterozoic in age (625–613 Ma).•The granitic rocks yielded εHf(t) of + 4.5 to + 8.4 and εNd(t) of + 4.1 to + 5.3.•Single zircon grains show a wide range in δ18O values of + 3.2‰ to + 6.4‰.•Hadb adh Dayheen rocks are consistent with melting of juvenile crustal protoliths.

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 ± 11 Ma for a hornblende–biotite granite sample, and 613 ± 4 Ma 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 1.1 Ga are inconsistent with depleted-mantle Nd model ages of 0.71 to 0.81 Ga 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.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slide

Related Topics
Physical Sciences and Engineering Earth and Planetary Sciences Geochemistry and Petrology
Authors
, , , , , ,