Laser Ablation Inductively Coupled Plasma Mass Spectrometry U-Pb Dating of Detrital and Magmatic Zircons of Glacial Diamictites and Pebbles in Late Ordovician Sediments of the Taurides and Southeast Anatolian Autochthon Belt, Turkey: Indications for Their Arabian-Nubian Provenance

Abstract

Late Ordovician (Hirnantian) glacio-marine deposits in the Central and Eastern Taurides and Southeast Anatolian Autochthon Belt (SAAB) in Turkey are mainly composed of diamictites, subrounded granitic pebbles, and rounded/subrounded lonestone pebbles. The granitic pebbles are dated as 576.5 ± 3.3, 576.7 ± 5.7, 598.4 ± 7.5, 717.5 ± 8.0, 789.5 ± 3.7, and 964.6 ± 4.6 Ma. The geochemical signatures and dated granitic pebbles in the Central and Eastern Taurides are interpreted to have been derived from the Late Neoproterozoic granitoids/metagranitic rocks of the Arabian-Nubian Shield (ANS; the Sinai Peninsula and the Eastern Desert of Egypt). The youngest 206Pb/238U ages in the diamictites (499.1 ± 4.2 Ma in the SAAB, 530.5 ± 5.3 Ma in the Eastern Taurides, and 562.5 ± 5.4 Ma in the Central Taurides) and in the lonestones (528.2 ± 4.5 Ma in the Central Taurides, 530.8 ± 5.2 Ma in the Eastern Taurides) indicate that detrital zircons were directly transported mainly from the northern margin of Gondwana and/or Arabia during the Late Ordovician, not from peri-Gondwanan parts of the European margin. Kernel/probability density diagrams of zircon ages from the lonestone pebbles in the Eastern and Central Taurides are interpreted as evidence for their derivation from Late/Middle Cambrian siliciclastic rocks in the Israeli part of the Sinai Peninsula. The provenance of detrital zircon populations in the diamictites in the Central and Eastern Taurides is directly correlated with magmatic activity of the Elat (Taba)–Feiran island arc, the Sa’al island arc, and the postcollisional magmatic suites in the Sinai Peninsula (Egypt). However, the corresponding successions in the SAAB have more abundant Late Cryogenian age components, suggesting the Ha’il/Afif/Ad Dawadimi/Ar-Rayn terranes of the eastern Arabian Shield as their provenance. These distinctive age patterns indicate that glacio-marine successions in the SAAB had different paleogeographic positions than their equivalent units in the Central and Eastern Taurides during deposition of the Late Ordovician glacio-marine units.