Neogene volcanism in Elazig-Tuceli area (eastern Anatolia): geochronological and petrological constraints

Samuele Agostini (1), Mehmet Yilmaz Savaşçin (2), Paolo Di Giuseppe (1,3), Flavio Di Stefano (4), Özgür Karaoğlu (5), Michele Lustrino (4,6), Piero Manetti (7,1), Yalçin Ersoy (8), Sevçan Kürüm (9) & Ayten Öztufekçi Önal (2)
(1) Istituto di Geoscienze e Georisorse, Consiglio Nazionale delle Ricerche (CNR), Via Moruzzi, 1, 56124 Pisa, Italy. (2) Jeoloji Müh. Bölümü Munzur Üniversitesi, 62000 Tunceli, Turkey. (3) Dipartimento di Scienze della Terra, Università di Pisa, Via Santa Maria, 53, 56126 Pisa, Italy. (4) Dipartimento di Scienze della Terra, Università La Sapienza, P.le A. Moro, 5, 00185 Roma, Italy. (5) Jeoloji Müh. Bölümü Eskisehir Osmangazi Üniversitesi, 26480 Eskisehir, Turkey. (6) Istituto di Geologia Ambientale e Geoingegneria, Consiglio Nazionale delle Ricerche (CNR), P.le A. Moro, 5, 00185 Roma, Italy. (7) Dipartimento di Scienze della Terra, Università degli Studi di Firenze, Via La Pira, 4, 50121 Firenze, Italy. (8) Jeoloji Müh. Bölümü Dokuz Eylül Üniversitesi, 35390 Izmir Turkey. (9) Jeoloji Müh. Bölümü, Firat Üniversitesi, 23110 Elazig, Turkey. Corresponding author e-mail: s.agostini@igg.cnr.it

The Elazığ and Tunceli provinces in eastern Anatolia host a complex succession of Miocene-Pleistocene effusive and explosive volcanic rocks, divided into four distinct volcanic phases. The most abundant and widespread products are the calcalkaline Mazgirt volcanic rocks, characterized by wide Sr isotope variations (87Sr/86Sr ~0.7054-0.7077) and narrower 143Nd/144Nd (~0.51246-0.51260) and Pb isotopes (e.g., 206Pb/204Pb ~18.89-19.13). New 40Ar-39Ar ages indicate that Mazgirt volcanic activity occurred between ~16.3 and 15.1 Ma. The other three volcanic phases are represented by the Tunceli mildly alkaline basaltic lavas (~11.4-11.0 Ma), the Pliocene Karakoçan (~4.1 Ma) and Pleistocene Elazığ (~1.9-1.6 Ma) Na-alkali basaltic lavas with clear OIB-like geochemical signature. Mazgirt volcanics can be subdivided on the base of mode of emplacement into lava flows and lava domes units characterized by petrographic, chemical and isotopic differences: lava flows are calcalkaline, whereas lava domes mostly belong to a high-K calcalkaline series and are, on average, more LREE- and 87Sr-enriched. Lava domes are more porphyritic, with a phenocryst assemblage dominated by amphibole, whereas plagioclase and clinopyroxene are the most abundant phenocryst phases in lava flows, pointing out that evolution of dome magmas occurred in conditions of slightly higher pressure, favouring the crystallization of hydrous phases. The Karabakır Formation, previously reported as late Miocene- Pliocene, encloses Mazgirt volcanics and is capped by Tunceli basalts. These new age data constrain the Karabakır Formation emplacement from early to late Miocene. The evolution of this igneous activity mirrors the geodynamic framework of the region: the early-middle Miocene Mazgirt volcanics represent arc volcanism related to Eurasia-Arabia convergence. The late Miocene Tunceli basalts postdate the onset of post-collisional tectonics in Eastern Anatolia, whereas the Karakoçan and Elazığ volcanic rocks were emplaced after the initiation of strike-slip motion on the North Anatolian and East Anatolian Fault systems.

Neogene volcanism, Eastern Anatolia, Ar-Ar geochronology, radiogenic isotopes, petrology.