The tectonic setting of the late Ediacaran eastern Arabian basement (ca. 550 Ma): New geochronological and geochemical constraints from the basements of Oman and the United Arab Emirates

The thick Phanerozoic sedimentary cover lying above the Arabian Platform conceals extensive basement between the western Neoproterozoic domains of the Arabian Nubian Shield (ANS) and of the eastern Omani basement. The Neoproterozoic rocks entrained within salt domes that crop out within the United Arab Emirates (UAE) and Qatar are the only direct samples that allow us to investigate the tectonic history of the concealed Arabian basement domains before c. 550 Ma. This study focuses on the U-Pb geochronological and REE geochemical analysis of detrital zircon, apatite, titanite and rutile grains from the Zirku turbidites brought to the surface by halokinetic movements offshore UAE. These data are compared with new U-Pb and REE data from detrital heavy minerals of three metasedimentary members of the Omani Neoproterozoic Hatat Formation collected in the Saih Hatat window. The Omani metasedimentary units yield detrital titanite, zircon and apatite U–Pb ages that span from c. 2500 to 690 Ma, with an age maxima at c. 850 Ma, while the UAE unit yield ages from c. 2550 to 550 Ma with major age peaks at c. 1000, 820, 650 Ma. The analysis of the Omani stratigraphic sequence in the Saih Hatat window revealed that the rocks of the Neoproterozoic Hatat Formation yield similar age distributions of the Abu Mahara Group (lower Huqf Supergroup, exposed in central and southern Oman), and that the REE geochemical composition of the Hatat detrital apatite grains shares akin REE signature with the c. 550 detrital apatite of the Zirku Formation, with both being sourced from volcanic-arcs. These new geochronological and geochemical data, together with recent geophysical evidences, suggest that the basement of the UAE is originally part of the Oman tectonic domain and evolved as part of a volcanic-arc in an active margin at c. 550 Ma, which we interpret as part of the retro-arc of the Cadomian collision in between the Arabian and the Cadomian Taurides, Iran and Afghanistan terranes.