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Jurassic-Paleogene intraoceanic magmatic evolution of the Ankara Mélange, north-central Anatolia, Turkey

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Abstract

<p><strong>Abstract.</strong> Oceanic rocks in the Ankara Mélange along the Izmir–Ankara–Erzincan suture zone (IAESZ) in north-central Anatolia include locally coherent ophiolite complexes (~<span class="thinspace"></span>179<span class="thinspace"></span>Ma and ~<span class="thinspace"></span>80<span class="thinspace"></span>Ma), seamount or oceanic plateau volcanic units with pelagic and reefal limestones (96.6<span class="thinspace"></span>±<span class="thinspace"></span>1.8<span class="thinspace"></span>Ma), metamorphic rocks with ages of 256.9<span class="thinspace"></span>±<span class="thinspace"></span>8.0<span class="thinspace"></span>Ma, 187.4<span class="thinspace"></span>±<span class="thinspace"></span>3.7<span class="thinspace"></span>Ma, 158.4<span class="thinspace"></span>±<span class="thinspace"></span>4.2<span class="thinspace"></span>Ma, and 83.5<span class="thinspace"></span>±<span class="thinspace"></span>1.2<span class="thinspace"></span>Ma indicating northern Tethys during the late Paleozoic through Cretaceous, and subalkaline to alkaline volcanic and plutonic rocks of an island arc origin (~<span class="thinspace"></span>67–63<span class="thinspace"></span>Ma). All but the arc rocks occur in a shale–graywacke and/or serpentinite matrix, and are deformed by south-vergent thrust faults and folds that developed in the middle to late Eocene due to continental collisions in the region. Ophiolitic volcanic rocks have mid-ocean ridge (MORB) and island arc tholeiite (IAT) affinities showing moderate to significant large ion lithophile elements (LILE) enrichment and depletion in Nb, Hf, Ti, Y and Yb, which indicate the influence of subduction-derived fluids in their melt evolution. Seamount/oceanic plateau basalts show ocean island basalt (OIB) affinities. The arc-related volcanic rocks, lamprophyric dikes and syenodioritic plutons exhibit high-K shoshonitic to medium- to high-K calc-alkaline compositions with strong enrichment in LILE, rare earth elements (REE) and Pb, and initial <i>&amp;epsilon;</i><sub>Nd</sub> values between +1.3 and +1.7. Subalkaline arc volcanic units occur in the northern part of the mélange, whereas the younger alkaline volcanic rocks and intrusions (lamprophyre dikes and syenodioritic plutons) in the southern part. The late Permian, Early to Late Jurassic, and Late Cretaceous amphibole-epidote schist, epidote-actinolite, epidote-chlorite and epidote-glaucophane schists represent the metamorphic units formed in a subduction channel in the northern Neotethys. The Middle to Upper Triassic neritic limestones spatially associated with the seamount volcanic rocks indicate that the northern Neotethys was an open ocean with its MORB-type oceanic lithosphere by the early Triassic (or earlier). The latest Cretaceous–early Paleocene island arc volcanic, dike and plutonic rocks with subalkaline to alkaline geochemical affinities represent intraoceanic magmatism that developed on and across the subduction–accretion complex above a N-dipping, southward-rolling subducted lithospheric slab within the northern Neotethys. The Ankara Mélange thus exhibits the record of ~<span class="thinspace"></span>120–130 million years of oceanic magmatism in geological history of the northern Neotethys.</p>

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APA

Sarifakioglu, E., Dilek, Y., & Sevin, M. (2014). Jurassic-Paleogene intraoceanic magmatic evolution of the Ankara Mélange, north-central Anatolia, Turkey. Solid Earth, 5(1), 77–108. https://doi.org/10.5194/se-5-77-2014

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