Geochronological and geochemical constraints and origin of the Tavşanlı Zone plutonic rocks (NW Turkey)

Abstract

Introduction The Anatolian plate is made up of various continental fragments and suture zones among them. These continental fragments are, from N to S, the Strandja Massif, the İstanbul and Sakarya Zones, the Anatolide-Tauride Block (Anatolide-Tauride Platform), the Central Anatolian Crystalline Complex (Kırşehir Massif, Kırşehir Block, Central Anatolian Massif), and the Arabian Platform (Şengör and Yılmaz, 1981; Şengör et al., 1982; Okay and Tüysüz, 1999) (Figure 1). The northwestern-western part of the Anatolide-Tauride Block consists of the Tavşanlı Zone, the Afyon Zone, and the Menderes Massif (Figure 1). The Tavşanlı Zone is a ~250 km long and ~50 km wide east-west trending belt located just south of the İzmir-Ankara-Erzincan Suture Zone (Figures 1 and 2) (Okay, 2008). This suture zone represents the northern Neo-Tethyan ocean, which began to open between Laurasia and Gondwana from the Middle-Late Triassic (Tekin et al., 2002) and started to close between the Sakarya Zone and the Anatolide-Tauride Block during the Late Cretaceous (in the west) (e.g., Tüysüz et al., 1995; Meijers et al., 2010; Lefebvre et al., 2013). Following the collision, convergence between the Sakarya Zone and the Anatolide-Tauride Block remained until the Late Tertiary (Şengör and Yılmaz, 1981). The zone is made up of blueschists tectonically overlain by an accretionary or mélange complex, peridotite slabs (Figure 2), and granodiorites (Okay et al., 1998). The blueschist sequence contains Permo-Triassic metapelitic schists at the base, overlain by Mesozoic marbles and a series of metabasite, metachert, and phyllite at the top (Okay, 1984). Metamorphic ages for the blueschists yield values between 80.

Late Paleocene – Middle Eocene magmatic flare-up in western Anatolia

“…5d). On the multi-element variation diagrams normalized to the primitive mantle after Sun and McDonough (1989), the rocks from the Sivrihisar-Günyüzü plutons display enriched large ion lithophile elements and negative anomalies of Nb-Ta, Sr and Ti, similar to the rocks formed in subduction-related environments (Kibici et al, 2008;Demirbilek et al, 2018;Bağcı et al, 2019). Chondritenormalized rare earth element patterns of the samples from the Sivrihisar-Günyüzü Plutons are variably steep, and display variably negative Eu anomalies (Fig.…”

“…Sr/Y ratios of the intermediate plutonic rocks after Hu et al (2017). Compositional data are from Harris et al (1994), Köprübaşı and Aldanmaz (2004), Kibici et al (2008), Ustaömer et al (2009), Altunkaynak et al (2012) Çelebi and Köprübaşı (2014), Demirbilek et al (2018), Sunal et al (2019), Bağcı et al (2019), Gürarslan and Altunkaynak, (2019) and Özyurt and Altunkaynak (2020). Table 1. Zircon U-Pb and Ar/Ar mica age data from northwest Anatolia.…”

“…There are about six plutons in this region all intruding the metamorphic rocks of the Tavşanlı Zone (Fig. 4, Kibici et al, 2008;Shin et al, 2013;Demirbilek et al, 2018;Bağcı et al, 2019). The closely spaced plutonic bodies between Günyüzü and Sivrihisar are probably connected at depth.…”

“…The Sivrihisar-Günyüzü Plutons are mainly medium-grained biotite-hornblende-bearing granodiorites and granites with subordinate monzonite, quartz-monzonite and syenite (Fig. 6a, Kibici et al, 2008;Shin et al, 2013;Demirbilek et al, 2018;Bağcı et al, 2019). The Sivrihisar Pluton consists of monzonite and the Dinek intrusion is largely quartz-monzonite.…”

“…5d). Geochemical data from the literature (Table S3; e.g., Kibici et al, 2008;Shin et al, 2013;Demirbilek et al, 2018;Bağcı et al, 2019) indicate that the granodiorites and granites belong to middle-to high-K calc-alkaline series, and monzonites and quartz-monzonites mainly to shoshonitic series on the SiO2 vs. K2O diagram of Peccerillo and Taylor (1976) (Fig. S1a).…”