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The Unaz Formation: A Key Unit in the Western Black Sea Region, N Turkey

2012-01-01
Tuysuz, Okan
Yılmaz, İsmail Ömer
Svabenicka, Lilian
Kirici, Sabri
The Pontide magmatic belt in the Western Pontides, which developed in response to the northward subduction of the northern branches of the Tethys Ocean, consists of two different volcanic successions separated by an Upper Santonian pelagic limestone unit, the Unaz Formation. The first period of volcanism and associated sedimentation started during the Middle Turonian and lasted until the Early Santonian under the control of an extensional tectonic regime, which created horst-graben topography along the southern Black Sea region. The lower volcanic succession, the Derekoy Formation, was deposited mainly within these grabens. This extensional period probably represents the rifting of magmatic arc, giving rise to the opening of the Western Black Sea back-intra-arc basin.