Evolution and provenance of Neoproterozoic basement and Lower Paleozoic siliciclastic cover of the Menderes Massif (western Taurides): Coupled U-Pb-Hf zircon isotope geochemistry

In the Menderes Massif (western Taurides) a Neoproterozoic basement comprising metasediments and intrusive granites is imbricated between Paleozoic platform sediments. U-Pb-Hf zircon analyses of Menderes rock units were performed by us using LA-ICP-MS. The U-Pb detrital zircon signal of the Neoproterozoic metasediments is largely consistent with a NE African (Gondwana) provenance. The oldest unit, a paragneiss, contains significant amounts (~. 30%) of Archean-aged zircons and εHf (t) values of about a half of its Neoproterozoic zircons are negative suggesting contribution from Pan-African terranes dominated by reworking of an old crust. In the overlying, mineralogically-immature Core schist (which is still Neoproterozoic), the majority of the detrital zircons are Neoproterozoic, portraying positive εHf (t) values indicating derivation from a proximal juvenile source, resembling the Arabian-Nubian Shield. The period of sedimentation of the analyzed metasediments, is constrained between 570 and 550Ma (Late Ediacaran). The Core schist sediments, ~9km thick, accumulated in less than 20My implying a tectonic-controlled sedimentary basin evolved adjacent to the eroded juvenile terrane. Granites, now orthogneisses, intruded the basin fill at 550Ma, they exhibit ±0 εHf (t=550Ma) and T_DM ages of 1.4Ga consistent with anatexis of various admixtures of juvenile Neoproterozoic and Late Archean detrital components. Granites in the northern Arabian-Nubian Shield are no younger than 580Ma and their εHf (t) are usually more positive. This implies that the Menderes does not represent a straightforward continuation of the Arabian-Nubian Shield. The lower part of the pre-Carboniferous silisiclastic cover of the Menderes basement, comprises a yellowish quartzite whose U-Pb-Hf detrital zircon signal resembles that of far-traveled Ordovician sandstones in Jordan (including 0.9-1.1. Ga detrital zircons), supporting pre-Triassic paleorestorations placing the Tauride with Afro-Arabia. The detrital signal of the overlying carbonate-bearing quartzitic sequence indicates contribution from a different source: the majority of its detrital zircons yielded 550. Ma and ± 0 εHf (t = 550. Ma) values identical to that of the underlying granitic gneiss implying exposure of Menderes-like granites in the provenance.260-250. Ma lead-loss and partial resetting of the U-Pb system of certain zircons in both basement and cover units was detected. It is interpreted as a consequence of a Permian-Early Triassic thermal event preceding known Triassic granitoid intrusions.