Detrital zircon ages and provenance of the triassic carpholite-bearing metaconglomerates in the southern menderes massif

Thesis Type: Postgraduate

Institution Of The Thesis: Orta Doğu Teknik Üniversitesi, Faculty of Engineering, Department of Geological Engineering, Turkey

Approval Date: 2013




The recent documentation of HP relics (carphiolite-bearing metaconglomerates) from the Kurudere area (Selimiye-Milas, Muğla) was one of the most important discoveries in the southern Menderes Massif. The metaconglomerates form the lowest most lithologies of the so-called marble unit and lie structurally above the schists with a proposed thrust fault. The metaconglomerates occur at two distinct horizons, each of which shows opposing sense of shearing in an overturned anticlinal structure. U–Pb–Hf zircon analyses of detrital zircons (450 grains) were performed by using Laser ablation induced couple mass spectrometry method (LA-ICPMS). The youngest grain is Asselian (earliest Permian) in age (298±5 Ma, conc. 104%) while a Mezoarchean zircon grain (3020±16 Ma; conc. 101%) forms the oldest. The youngest zircon grain is therefore consistent with previous contention that the metaconglomerate is late Triassic in age. The dominance of Ordovician to Cryogenian (Neoproterozoic) zircons and lack of Mesoproterozoic (1.11.7 Ga) zircons suggest Pan-African terranes (the northern Gondwana provenance) as the main source area. εHf values of 144 zircon grains indicate both reworking of an old crust and a juvenile crustal source. The detrital zircon populations and εHf values are very distinct from those reported in the southern Menderes metasediments and show pronounced similarities with that of Cycladic rocks. It is therefore concluded that the Kurudere HP metaconglomerates and possibly the overlying marbles in the southern Menderes Massif may belong to the Cycladic blueschist units. The occurrence of north-vergent overturned fold and associated kinematics suggest tectonic emplacement of the Cycladic unit above the Menderes sequence sometime after Eocene but before late Oligocene.