Petrogenesis of the post-collisional Eocene volcanic rocks from the Central Sakarya Zone (Northwestern Anatolia, Turkey)
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ORIGINAL PAPER
Petrogenesis of the post-collisional Eocene volcanic rocks from the Central Sakarya Zone (Northwestern Anatolia, Turkey): Implications for source characteristics, magma evolution, and tectonic setting Ahmet Yildiz 1 & Yaşar Kibici 2 & Metin Bağci 1 & İbrahim Dumlupunar 1 & Cumhur Kocabaş 3 & A. Ekrem Aritan 1
Received: 16 April 2015 / Accepted: 4 June 2015 # Saudi Society for Geosciences 2015
Abstract Eocene volcanic rocks from the Central Sakarya Zone in the north of the İzmir–Ankara suture zone (IASZ) are predominantly intermediate-acidic lava flows and pyroclastics that crop out with a W–E orientation. The volcanic rocks include Bozaniç lavas, agglomerates, İğdir lavas, and Kapıkaya tuffs. The Bozaniç lavas contain plagioclase, hornblende, clinopyroxene, and biotite, whereas the İğdir lavas consist of plagioclase, hornblende, biotite, and quartz. According to the total alkali–silica (TAS) diagram, the Bozaniç lavas are mainly composed of andesite and dacite, with one sample of trachyandesite, whereas the İğdir lavas mainly contain dacite and minor andesite. Bozaniç and İğdir lavas exhibit moderate- to high-K calc-alkaline character. Major oxide and trace element variations suggest the effects of fractional crystallization in the evolution of the volcanic rocks. N-type midocean ridge basalt (MORB) normalized trace element patterns
* Ahmet Yildiz [email protected] Yaşar Kibici [email protected] Metin Bağci [email protected] İbrahim Dumlupunar [email protected] Cumhur Kocabaş [email protected] A. Ekrem Aritan [email protected] 1
Faculty of Engineering, Afyon Kocatepe University, Afyonkarahisar, Turkey
2
Faculty of Engineering, Dumlupınar University, Kütahya, Turkey
3
Faculty of Engineering, Balıkesir University, Balıkesir, Turkey
of the lavas exhibit enrichment in large ion lithophile elements (LILEs; K, Rb, Ba, Th) and depletion in high field strength elements (HFSEs; Zr, Ti, Y). In addition, the chondritenormalized rare earth element (REE) plots of the rocks show moderately enriched and nearly concave-shaped patterns (LaN/YbN = 5.4–17.6 for the Bozaniç lavas and 6.5–13.1 for the İğdir lavas), suggesting clinopyroxene (Cpx) and hornblende dominated fractionation. Negative Eu anomalies in the acidic lavas reveal plagioclase fractionation. Some trace element ratios of the lavas demonstrate a subduction signature and crustal contamination in the generation of the parent magma(s). Multi-dimensional tectonic discrimination diagrams suggest that the studied volcanic rocks have developed in a collisional setting. Keywords Post-collision . Volcanism . Calc-alkaline . Sakarya continent . Turkey
Introduction The collision between the Arabian and Eurasian plates, subduction of the African plate under the Aegean-Anatolian plates, and the N–S-directed extension ensured the tectonic evolution of Anatolia (Şengör and Yılmaz 1981; Ring et al. 2010; Leroy et al. 2014; Al-Dabbagh 2014). The subduction and elimination of the northern branch of Neo-Tethyan northward beneath the Sakarya continent
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