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 TDM 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.
Bibliographical noteFunding Information:
This research was supported by the G.I.F., the German–Israeli Foundation for Scientific Research and Development (grant number 977‐168, 8/2007 ). We thank Erdin Bozkurt for his supportive cooperation all along this project and for a joint field trip; Talip Gungor, Uwe Ring and Klaus Gessner for leading a memorable Samos-Menderes GSA field forum which provided important insights for this study. Zvi Garfunkel is thanked for clarifying many aspects of eastern Mediterranean geology. Discussions with Navot Morag on various aspects of the U–Pb–Hf system are very much appreciated. Reviews by Ersin Koralay, Osman Candan and Klaus Gessner were extremely helpful and greatly improved this manuscript.
- Early Paleozoic
- Late Neoproterozoic
- Peri-Gondwanan terranes
- U-Pb zircon geochronology
- U-Pb-Hf zircon isotope geochemistry