On the geodynamics of the Alpine collisional granitoids from Central Anatolia: petrology, age and isotopic characteristics of the granitoids of the Ekecikdağ Igneous Association (Aksaray/Turkey)

Fatma Toksoy-Köksal

doi:10.1080/09853111.2019.1597677

Abstract

ABSTRACTGranitoids of the Ekecikdağ Igneous Association (Central Anatolia/Turkey) are products of collisional–post-collisional magmatism in the Ekecikdağ area. These granitoids are granodiorite, microgranite and leucogranite. Field relations of granodiorites with microgranites is obscured, but leucogranites intrude both rock types. Mean zircon laser ablation (LA)-ICP-MS 206Pb-238U ages of granodiorites and microgranites are 84.52 ± 0.93 Ma and 80.7 ± 1.6 Ma, respectively, and age of leucogranites is suggested as 80 Ma, based on field relations combined with 206Pb/238U and Rb-Sr ages. Crystallisation temperatures of granodiorites, microgranites and leucogranites are 728°C-848°C, 797°C-880°C, 704°C-809°C, respectively.Geochemical characteristics including Sr-Nd isotopic evidences infer a non-cogenetic character, as there is a high crustal contribution in I-type granodiorite sources, a crustal source with insignificant and significant mantle inputs in S-type microgranites and leucogranites, respectively. LA-ICP-MS Lu-Hf isotope data from zircons reveal their crustal nature (εHf(t): −1.3 ± 0.5 to −8.8 ± 0.5). Crustal melting linked to the Alpine thickening during the Late Cretaceous led to formation of heterogeneous sourced granitoids with crustal dominated sources in the Ekecikdağ area. Understanding of the nature and evolution of collisional Ekecikdağ granitoids is not only important to put contribution in the geodynamic evolution of Central Anatolia and surrounding Alpine area, but also to better understand systematics of collisional magmatic systems.

Highlights

Granitoids are significant for the Alpine geological context since their petrology reflects aspects of closure of oceanic branches and evolution of the continental crust
These authors linked the generation of the Central Anatolian Crystalline Complex (CACC) granitoids with the Andean type arc formed due to the NE dipping subduction zone beneath the CACC through which the Inner Tauride oceanic lithosphere consumed during the Late Cretaceous (e.g. Deniz & Kadıoğlu, 2016; Kadıoğlu et al, 2006, 2003) or in the Paleocene-Early Eocene (e.g. Görür et al, 1984)
This study aims to provide new insight on the petrogenesis of the Ekecikdağ Igneous Association (EIA), as an example of the collisional igneous complexes in the Alpine realm, by using geochronological, whole rock Sr-Nd and zircon Lu-Hf isotope data

Summary

Introduction

Granitoids are significant for the Alpine geological context since their petrology reflects aspects of closure of oceanic branches and evolution of the continental crust. One group of scientists advocates the existence of the Inner Tauride Suture separating the Tauride block from the Anatolide block (Deniz & Kadıoğlu, 2016; Görür et al, 1984; Kadıoğlu et al, 2003; Okay et al, 1996; Şengör & Yılmaz, 1981). These authors linked the generation of the Central Anatolian Crystalline Complex (CACC) granitoids with the Andean type arc formed due to the NE dipping subduction zone beneath the CACC through which the Inner Tauride oceanic lithosphere consumed during the Late Cretaceous

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