ARTICLE The late Oligocene Cevizlidere Cu-Au-Mo deposit, Tunceli Province, eastern Turkey Ali İmer & Jeremy P. Richards & Robert A. Creaser & Terry L. Spell Received: 17 March 2013 /Accepted: 6 June 2014 /Published online: 21 June 2014 # Springer-Verlag Berlin Heidelberg 2014 Abstract The Cevizlidere deposit, located in the Tunceli Prov- ince of eastern Anatolia, is the largest porphyry Cu-Au-Mo system in Turkey. The deposit is spatially related to a composite stock, which was emplaced into Paleozoic lime- stones and Paleogene andesitic rocks to the southeast of the Munzur mountains, near the southwestern margin of the Ovac ı k pull-apart basin. The host plutonic rocks at Cevizlidere are porphyritic, medium-K calc-alkaline diorites and granodiorites. 40 Ar/ 39 Ar incremental step-heating analysis of two igneous biotite separates obtained from syn-mineral diorite porphyry yielded late Oligocene cooling ages of 25.49 ±0.10 and 25.10±0.14 Ma, whereas hydrothermal biotite yielded an age of 24.73±0.08 Ma. Re-Os ages obtained from two molybdenite separates (24.90±0.10 and 24.78±0.10 Ma) indicate that porphyry-style alteration and mineralization de- veloped shortly after magma emplacement. The whole-rock geochemical composition of the Cevizlidere porphyry intru- sions is consistent with derivation from partial melting of the metasomatized supra-subduction zone mantle. However, based on regional tectonic reconstructions, Oligocene mag- matic activity in this area appears to be related to a major kinematic reorganization that took place at around 25 Ma, during the switch from subduction to collisional tectonics in eastern Anatolia. This kinematic switch may be attributed to break-off of the Southern Neo-Tethys oceanic slab prior to the Arabia–Eurasia continent-continent collision (~12–10 Ma) following widespread middle Eocene (50–43 Ma) arc/back- arc magmatism. In this respect, the subduction-related tectonic setting of the late Oligocene Cevizlidere porphyry deposit is similar to that of the middle Eocene Çöpler epithermal Au deposit. The late timing of Cevizlidere with respect to the Southern Neo-Tethys subduction may be comparable to some early to late Miocene porphyry-epithermal systems that lie within the contiguous Urumieh-Dokhtar belt in central Iran. The later timing in Iran reflects the diachronous nature of the Eurasia-Afro-Arabia collision. Keywords Porphyry Cu-Au-Mo deposit . Tauride- Anatolide Block . EasternAnatolia . Turkey . Late Oligocene . Pre-collision . Neo-Tethys Introduction Eastern Anatolia has experienced complex collisional oro- genic events since at least the Late Mesozoic, relating to closure of the Neo-Tethyan oceanic basin and ultimate collision between Eurasia and Arabia. As a result of this convergence, the orogenic belt experienced prolonged in- tervals of arc and back-arc magmatism during the Late Cretaceous (ca. 80–70 Ma) and middle Eocene (ca. 50– 44 Ma) above the northward subducting Neo-Tethys oce- anic plate. Subduction-related magmatism was followed by a period of widespread collision-related and post-collisional volcanic activity starting in the middle Miocene (ca. 17 Ma; Kürüm et al. 2008) and continuing to the present day. In eastern Anatolia, several porphyry Cu±Mo±Au and epithermal Au deposits are associated with Late Cretaceous and middle Eocene subduction-related magmatic centers, such as the Çöpler porphyry-epithermal Au-Cu deposit, Editorial handling: G. Beaudoin and G.J. Davidson Electronic supplementary material The online version of this article (doi:10.1007/s00126-014-0533-4) contains supplementary material, which is available to authorized users. A. İmer : J. P. Richards (*) : R. A. Creaser Department of Earth & Atmospheric Sciences, University of Alberta, Edmonton, Alberta T6G 2E3, Canada e-mail: Jeremy.Richards@ualberta.ca T. L. Spell Department of Geoscience, University of Nevada, Las Vegas, 4505 Maryland Parkway, Las Vegas, NV 89154-4010, USA Miner Deposita (2015) 50:245–263 DOI 10.1007/s00126-014-0533-4