U-Pb zircon geochronology of intrusive rocks from an exotic block in the Late Cretaceous – Paleocene Taraklı Flysch (northern Turkey): Constraints on the tectonics of the Intrapontide suture zone

Abstract

In the Boyalı area (northern Anatolia), a thick succession of the Early Maastrichtian-Middle Paleocene Taraklı Flysch crops out. The Taraklı Flysch represents a foredeep deposit sedimented during the final stage of collision between Sakarya and Istanbul-Zonguldak continental margins, that developed as consequence of the closure of the Intrapontide oceanic basin. The top of the Taraklı Flysch is characterized by a level of slide-block in shaly-matrix lithofacies that can be considered as a fast catastrophic event predating the closure of the basin and its deformation. This level consists of slide-blocks sourrounded by monomict pebbly-mudstones and pebbly-sandstones. Among the slide-blocks, the biggest one consists of quartz-monzonites and leucocratic granodiorites of Late Permian age (260.8 ± 2.2 Ma) dated by zircon LA-ICP-MS method. By comparison with the regional data, the source area of these granitoids can be identified in the Istanbul-Zonguldak terrane. This evidence suggests a new picture for the paleogeographic setting of the ultimate stage of the continental collision between the Istanbul-Zonguldak and Sakarya continental margins. In this scenario the coarse-grained deposits of the Taraklı Flysch are supplied by an orogenic wedge, consisting of oceanic units topped by the Istanbul-Zonguldak terrane. This orogenic wedge represents the northern side of the foredeep, where the southern one is represented by the still undeformed Sakarya continental margin.

Sedimentary Provenance From the Evolving Forearc‐to‐Foreland Central Sakarya Basin, Western Anatolia Reveals Multi‐Phase Intercontinental Collision

“…Adapted from Akdoğan et al (2017), Okay &Nikishin (2015) and references therein. Darin et al, 2018;Di Rosa et al, 2019;Göncüoğlu et al, 2014). Table 1.…”

“…In line with this relict basin closure scenario, major collisional deformation from initial TVZ-SKZ underthrusting could be delayed by >20 Myr due to the closure of relict basins to the north or south of the İAES (Figure 10b). The closure of the Intra-Pontide suture zone is a strong candidate to explain this delay because the timing of suturing remains unclear, with proposed ages spanning from the Early Cretaceous (Akbayram et al, 2013), to the Late Cretaceous-Paleocene (Di Rosa et al, 2019;Göncüoğlu et al, 2000;Özcan et al, 2012;Robertson & Ustaömer, 2004), and to the Paleocene-Eocene (Akbayram et al, 2016;Göncüoğlu et al, 2014;Okay et al, 1994). Major contractional deformation could also be delayed by the hypothesized southward-jumping subduction zones synchronously or sequentially facilitating the closure of Neotethyan oceanic basins between Anatolide and Tauride terranes south of the İAES (Pourteau et al, 2013(Pourteau et al, , 2016.…”

“…In line with this relict basin closure scenario, major collisional deformation from initial TVZ‐SKZ underthrusting could be delayed by >20 Myr due to the closure of relict basins to the north or south of the İAES (Figure 10b). The closure of the Intra‐Pontide suture zone is a strong candidate to explain this delay because the timing of suturing remains unclear, with proposed ages spanning from the Early Cretaceous (Akbayram et al., 2013), to the Late Cretaceous‐Paleocene (Di Rosa et al., 2019; Göncüoğlu et al., 2000; Robertson & Ustaömer, 2004; Z. Özcan et al., 2012), and to the Paleocene‐Eocene (A. I. Okay et al., 1994; Akbayram et al., 2016; Göncüoğlu et al., 2014).…”

“…Figure 10. Schematic diagram of multi-phase collision scenarios (inspired byDarin et al, 2018;Di Rosa et al, 2019;Göncüoğlu et al, 2014). (a) Tavşanlı Zone slab breakoff.…”

A Review of the Dynamics of Subduction Zone Initiation in the Aegean Region

“…In Greece, the Vardar suture connects to the IPS (Şengör & Yılmaz, 1981;Okay & Satir, 2000;Okay et al, 2001;Beccaletto & Jenny, 2004;Okay et al, 2010;d'Atri et al, 2012;Di Rosa et al, 2019) or Meliata-Balkan suture (Stampfli, 2000). In Turkey's Biga Penisula, the IPS and Vardar connection may be recorded by an isolated ophiolite-bearing accretionary complex active manuscript accepted to AGU Books until the Late Cretaceous (Figure 5) (e.g., Okay et al, 1991).…”