Temporal, geochemical and geodynamic evolution of the Late Cretaceous subduction zone volcanism in the eastern Sakarya Zone, NE Turkey

Implications for mantle-crust interaction in an arc setting

Document identifier: oai:DiVA.org:ltu-77781
Access full text here:10.1016/j.jseaes.2019.104217
Keyword: Natural Sciences, Earth and Related Environmental Sciences, Geochemistry, Naturvetenskap, Geovetenskap och miljövetenskap, Geokemi, Late Cretaceous, Subduction, Volcanism, Mantle–crust interaction, Sakarya Zone, Eastern Pontides, NE Turkey, Applied Geochemistry, Tillämpad geokemi
Publication year: 2020
Abstract:

The Late Cretaceous Artvin volcanic rocks (LCAVs) from the eastern Sakarya zone (ESZ) of NE Turkey are composed of mafic/basaltic (S1-Çatak and S2-Çağlayan) and felsic/acidic (S1-Kızılkaya and S2-Tirebolu) rock types that occurred in two successive stages: (i) first stage (S1: Turonian–Early Santonian) and (ii) second stage (S2: Late Santonian–Campanian). Clinopyroxene thermobarometric results point that the S2-Çağlayan basaltic rocks have crystallised at higher temperatures and under deeper crustal conditions than those of the S1-Çatak basaltic rocks.

The LCAVs show a wide compositional spectrum, ranging from tholeiite to calc-alkaline/shoshonite and are typically represented by a geochemical composition resembling subduction-related arc rocks although the 87Sr/86Sr(i) (0.7044–0.7071) and ɛNd(i) values (−0.63 to + 3.47) as well as 206Pb/204Pb(i) (18.07–18.56), 207Pb/204Pb(i) (15.57–15.62) and 208Pb/204Pb(i) (37.12–38.55) ratios show very limited variation. The parent magmas of the S1-Çatak and S2-Çağlayan mafic volcanic rocks were derived from underplated basaltic melts that originated by partial melting of metasomatised spinel lherzolite and spinel-garnet lherzolite, respectively. It is proposed that the compositions of the S1-Kızılkaya (mainly dacitic) and S2-Tirebolu (rhyolitic to trachytic) felsic rocks were particularly controlled by metasomatised mantle–crust interaction and MASH zone + shallow crustal fractionation processes. Our data, together with data from previous studies, suggest that the S1- and S2-mafic and felsic rocks of the LCAVs (~95–75 Ma) are the products of two-stage volcanic event that took place during the northward subduction of the northern Neotethys Ocean (NNO).

Authors

Faruk Aydin

Karadeniz Technical University, Department of Geological Engineering
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Simge Oguz Saka

Karadeniz Technical University, Department of Geological Engineering
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Cüneyt Sen

Karadeniz Technical University, Department of Geological Engineering
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Abdurrahman Dokuz

Gümüşhane University, Department of Geological Engineering
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Thomas Aiglsperger

Luleå tekniska universitet; Geovetenskap och miljöteknik
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Ibrahim Uysal

Karadeniz Technical University, Department of Geological Engineering
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Raif Kandemir

Recep Tayyip Erdoğan University, Department of Geological Engineering
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Orhan Karsli

Recep Tayyip Erdoğan University, Department of Geological Engineering
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Bilal Sari

Dokuz Eylül University, Department of Geological Engineering
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Rasim Baser

Karadeniz Technical University, Department of Geological Engineering
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