Late Cretaceous eclogitic high-pressure relics in the Bitlis Massif

Abstract

A new occurrence of eclogites was found in the Kesandere valley in the eastern most part of the Bitlis complex, SE Anatolia. These high-pressure (HP) relics were preserved in calc-arenitic metasediments within the high-grade metamorphic basement of the Bitlis complex. The eclogitic parageneses were strongly overprinted during decompression and heating. These new eclogites locality complements the evidence of blueschist-facies metamorphism documented recently in the meta-sedimentary cover sequence of this part of the Bitlis complex. Thermodynamic calculations suggest peak conditions of ca. 480-540°C/1.9-2.4 GPa. New U/Pb dates of 84.4 ± .9 and 82.4 ± .9 Ma were obtained on zircons from two Kesandere eclogite samples. On the basis of geochemical criteria, these dates are interpreted to represent zircon crystallization during the eclogitic peak stage. Kesandere eclogites differ from those previously described in the western Bitlis complex (Mt. Gablor locality) in terms of lithologic association, protolithic origin, and peak P-T conditions (600-650°C/1.0-2.0 GPa, respectively). On the other hand, eclogitic metamorphism of Kesandere metasediments occurred shortly before blueschist-facies metamorphism of the sedimentary cover (79-74 Ma 40 Ar/ 39Ar white mica). Therefore, the exhumation of Kesandere eclogites started between ca. 82 and 79 Ma, while the meta-sedimentary cover was being buried. During this short time span, Kesandere eclogite were likely uplifted from~65 to 35 km depth, indicating a syn-subduction exhumation rate of~4.3 mm/a. Subsequently, eclogite-and blueschist-facies rocks were likely retrogressed contemporarily during collision-type metamorphism (around 72-69 Ma). The Bitlis HP rocks thus sample a subduction zone that separated the Bitlis-Pütürge (Bistun?) block from the South-Armenian block, further north. To the south, Eocene metasediments of the Urse formation are imbricated below the Bitlis complex. They contain (post Eocene) blueschists, testifying separation from the Arabian plate and southward migration of the subduction zone. The HT overprint of Kesandere eclogites can be related to the asthenospheric flow provoked by subducting slab retreat or break off.

Cadomian basement and Paleozoic to Triassic siliciclastics of the Taurides (Karacahisar dome, south-central Turkey): Paleogeographic constraints from U–Pb–Hf in zircons

“…Bozkurt, 2001;Bozkurt, 2007;Bozkurt and Oberhansli, 2001;Bozkurt and Park, 1994;Candan et al, 2001;Catlos and Çemen, 2005;Dannat and Reischmann, 1999;Gessner et al, 2001;Koralay et al, 2006;Koralay et al, 2012;Loos and Reischmann, 1999;Oberhansli et al, 1997;Oberhansli et al, 2010;Oberhansli et al, 2013;Okay, 2001;Ustaömer et al, 2009;Ustaömer et al, 2012;Zlatkin et al, 2013). The Karacahisar area was not affected by severe metamorphism (Dumont, 1972;Gürsu et al, 2003;Gutnic, 1979;Kröner and Şengör, 1990), it is located closer to the A C C E P T E D M A N U S C R I P T 7 southern edge of the Taurides, and it contains a transgressive Cambro-Ordovician cover section.…”

Kinematics of Late Cretaceous subduction initiation in the Neo‐Tethys Ocean reconstructed from ophiolites of Turkey, Cyprus, and Syria

“…We suggest that ophiolites emplaced onto the Bitlis massif, which we associate to the Arabian margin, were also part of this microplate and arrived on the Bitlis margin withiñ 10 Myr of subduction initiation. This would explain the~85-80 Ma high-pressure metamorphism in the Bitlis massif [Oberhänsli et al, 2014[Oberhänsli et al, , 2012. The Göksun ophiolite also arrived within~10 Myr after subduction initiation onto continental crust, but in this case of the southeastern Taurides, opposite to the oceanic embayment that separated Arabia and the Taurides.…”

Neotethyan closure history of western Anatolia: a geodynamic discussion

“…Stampfli and Hochard 2009) and the complex Neotethyan palaeogeography of the East Mediterranean (e.g. Sengör and Yilmaz 1981;Robertson et al 1996;Moix et al 2008;Oberhänsli et al 2013), justify the still ongoing discussion on the tectonic and palaeogeographic correlation of the two areas (e.g. Brunn et al 1976;Sengör and Yilmaz 1981;Dercourt et al 1993;Ring et al 1999a;Jolivet et al 2004;Schmid et al 2013).…”