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Lead isotope geochemistry of Pb-Zn deposits from Eastern Taurides, Turkey

Ceyhan, Nuri
This study is concerned with the Pb-isotope compositions of galena samples from Pb-Zn occurrences in southern Turkey. The purpose is to i) provide chronologic information for ore deposition, ii) investigate the likely source(s) of lead in ore deposits, and iii) examine the possible control of tectonic setting and crustal basement on Pb-isotope compositions. The data used in the study belongs to the deposits located in Taurides (Zamanti, Kahramanmaras, Malatya, Elazig, Bitlis), with additional data from Nigde Massif and Hakkari Area. The mineralizations are dominantly carbonate-hosted Pb-Zn deposits formed as fracture and karst fillings and, in some places, parralel to bedding. Ore minerals are mainly Zn-oxides and minor Zn, Pb-sulphides. The Pb-isotope compositions, as evaluated in terms of their configuration with respect to reference crustal growth curves and reference isochrons on conventional Pb-isotope diagrams, point to U/Pb ratios greater than average crustal values (and close to the Western Mediterranean Crustal Growth Curve) for all the deposits, indicating upper crustal source for Pb. However, some of the deposits (Afsin-Kahramanmaras; Oreks, Dündarli, Agcasar and skarn type deposits to the south of Çadirkaya in Zamanti (Kayseri-Adana); Keban-Elazig) appear to have magmatic inputs in their genesis. Relatively old deposits are likely Paleozoic (Cafana-Malatya and Türksevin-Kahramanmaras), Late Paleozoic-Early Mesozoic (Kaleköy-Zamanti) and Mesozoic (Hakkari) in age. The rest of the deposits (most of the occurrences in Zamanti, Nigde, Kahramanmaras, Elazig and Bitlis) are likely of Cenozoic age. The Pb-isotope compositions are, in general, similar to those from other occurrences in the