The Intra-Pontide ophiolites in Northern Turkey revisited: From birth to death of a Neotethyan oceanic domain

Abstract

The Anatolian peninsula is a key location to study the central portion of the Neotethys Ocean(s) and to understand how its western and eastern branches were connected. One of the lesser known branches of the Mesozoic ocean(s) is preserved in the northern ophiolite suture zone exposed in Turkey, namely, the Intra-Pontide suture zone. It is located between the Sakarya terrane and the Eurasian margin (i.e., Istanbul-Zonguldak terrane) and consists of several metamorphic and non-metamorphic units containing ophiolites produced in supra-subduction settings from the Late Triassic to the Early Cretaceous. Ophiolites preserved in the metamorphic units recorded pervasive deformations and peak metamorphic conditions ranging from blueschist to eclogite facies. In the non-metamorphic units, the complete oceanic crust sequence is preserved in tectonic units or as olistoliths in sedimentary mélanges. Geochemical, structural, metamorphic and geochronological investigations performed on ophiolite-bearing units allowed the formulation of a new geodynamic model of the entire “life” of the Intra-Pontide oceanic basin(s). The reconstruction starts with the opening of the Intra-Pontide oceanic basins during the Late Triassic between the Sakarya and Istanbul-Zonguldak continental microplates and ends with its closure caused by two different subductions events that occurred during the upper Early Jurassic and Middle Jurassic. The continental collision between the Sakarya continental microplate and the Eurasian margin developed from the upper Early Cretaceous to the Palaeocene. The presented reconstruction is an alternative model to explain the complex and articulate geodynamic evolution that characterizes the southern margin of Eurasia during the Mesozoic era. Keywords: Intra-Pontide suture zone, Central Pontides, Northern Turkey, Ophiolites, Neotethys Ocean, Geodynamics