Article 2021 · 5 citations

Geochemistry and U-Pb ages from the Kosdag Metavolcanics in the southern Central Pontides (Turkey): Complementary data for early Late Cretaceous island arc development in the Northern Neotethys

Berber, Faruk, Sayit, Kaan, Goncuoglu, Mehmet Cemal

Abstract

The Kosdag Metavolcanics (KMs) in the southern Central Pontides are exposed between the Izmir-Ankara-Erzincan Suture Belt in the south and the Sakarya Composite Terrane in the north. They comprise an approximately 40-km-long tectonic unit, bounded by the splays of the North Anatolian Transform Fault in the north and the Kizilca Thrust in the south. The basement of the unit mainly consists of metabasalts, metaandesites, and metarhyolites, with well-developed blastomylonitic textures, which are interlayered by recrystallized pelagic limestone and chert. Late Cretaceous pelagic limestones of the Dikmen Formation disconformably overlie the basement. Geochemically, the KMs exhibit enrichment in Th and La relative to Nb (and Ti), indicating subduction-related magmatic signatures. The KMs are subdivided into two main types, as Type 1 and Type 2, based on their relative Zr-Hf enrichment/depletion features. All of the members of the KMs have a subalkaline nature (Nb/Y - 0.08-0.19 for Type 1; Nb/Y = 0.05-0.13 for Type 2) and display a calc-alkaline affinity. The high Zr/Nb (38.1-52.9 for Type 1, 21.8-41.2 for Type 2), low Zr/Y (4.07-5.25 for Type 1, 1.58-2.44 for Type 2), and Nb/Y (0.08-0.14 for Type 1,0.05-0.10 for Type 2) signatures of the KMs indicate that they have derived from a depleted source, which has been modified by a subduction component. The laser ablation inductively-coupled plasma mass spectrometry (LA-ICP-MS) U-Pb zircon ages of the metarhyolite samples ranged between 94.64 +/- 0.77 Ma and 113.2 +/- 2.3 Ma, suggesting the presence of an intraoceanic subduction zone during the early Late Cretaceous within the Izmir-Ankara-Erzincan branch of the Neotethys Ocean in the Central Pontides.

Keywords

Central Pontides early Late Cretaceous Izmir-Ankara-Erzincan Suture Belt island arc Kosdag Metavolcanics TECTONIC EVOLUTION SUTURE ZONE RADIOLARIAN CHERTS KARAKAYA COMPLEX ANKARA MELANGE MIDDLE OPHIOLITES SUBDUCTION BASALTS ROCKS

WoS Categories

Geosciences, Multidisciplinary

Sustainable Development Goals

Climate Action

Citation

Journal: TURKISH JOURNAL OF EARTH SCIENCES
Year: 2021
Volume: 30
Issue: 1
Pages: 59-80
ISSN: 1300-0985
DOI: 10.3906/yer-2004-16
WoS UID: WOS:000608378100004

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