International Geological Journal - Official Journal of the Carpathian-Balkan Geological Association

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Geochronology and petrogenesis of the lower Miocene felsic rocks: New evidence for initiation of post-collisional magmatism in the SW Malatya – Eastern Anatolia (Turkey)

Published: Jun 2023

Pages: 245 - 260

DOI: https://doi.org/10.31577/GeolCarp.2023.12

Authors: MEHMET ALI ERTÜRK, HATICE KARA, ABDULLAH SAR, İSAK YILMAZ, NAMIK AYSAL

Abstract: The Southeast Anatolian Orogenic Belt (SAOB) consists of various tectono-magmatic and tectono-stratigraphic units such as metamorphic massifs, granitoids, ophiolites and volcanic rocks. In this study, we report new zircon U–Pb LA-ICP-MS ages, Sr–Nd isotope analysis and whole-rock geochemistry from Miocene felsic (dacitic and rhyolitic) rocks cross-cutting the Permo–Triassic Malatya metamorphic complex to determine the source of magmatism and magmatic processes in the region. The zircon U–Pb crystallisation ages are between 16.66 ± 0.23 Ma and 16.83 ± 0.094 Ma, implying the start of the post-collisional volcanism in the Early Miocene (Burdigalian) period. Volcanic rocks have calc-alkaline and high-K calc-alkaline characters. The 87Sr/86Sr values for the felsic volcanics range between 0.707098 and 0.711703. The initial 143Nd/144Nd ratios are between 0.512446 and 0.512469, and the εNd values vary from −3.12 to −3.66. The Nd (TDM) model ages are between 1.05 and 1.13 Ga. Negative εNd values and Nd (TDM) model ages show great similarities with the Precambrian basement in Turkey, Iran and the Arabian peninsula. Energy-constrained assimilation–fractional crystallisation (EC-AFC) models testing different crustal sources using Sr–Nd isotope data show that primary magmas contain significant crustal melt contributions. Geochemical data indicate that the felsic rocks may have originated from crust-derived melts mixed with lithospheric mantle-derived mafic melts during its residence in the upper crust in a post-collisional tectonic setting.

Keywords: felsic rocks, zircon U–Pb ages, lithospheric mantle, upper crust, post-collisional volcanism, Eastern Turkey

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