Early Cretaceous sedimentation and orogeny on the active margin of Eurasia: Southern Central Pontides, Turkey

Abstract

The Pontides in northern Turkey constituted part of the southern active margin of Eurasia during the Mesozoic. In the Early Cretaceous, a large submarine turbidite fan covered most of the Central Pontides. New U‐Pb detrital zircon data imply that the major source of the turbidites was the East European Craton‐Scythian Platform in the north. This implies that there was no thoroughgoing Black Sea basin between the Pontides and the East European Craton during the Early Cretaceous. The Lower Cretaceous turbidites are bounded in the south by a large metamorphic area, the Central Pontide Supercomplex (CPS). New geological mapping, petrology, and U‐Pb zircon and Ar‐Ar muscovite ages indicate that the northern part of the CPS consists of Lower Cretaceous distal turbidites deformed and metamorphosed in a subduction zone in the Albian. The rest of the CPS is made of Middle Jurassic, Lower Cretaceous, and middle Cretaceous (Albian) metamorphic belts, each constituting distinct subduction‐accretion units. They represent episodes of collision of oceanic volcanic arcs and oceanic plateaus with the Eurasian margin and are marked in the stratigraphy of the hinterland by periods of uplift and erosion. The accretionary complexes are overlain by Upper Cretaceous (Turonian‐Santonian) volcano‐sedimentary sequences deposited in a fore‐arc setting. The detrital zircon data, middle Cretaceous (Albian) metamorphism, and widespread Albian uplift of the Black Sea region suggest that Early Cretaceous (Barremian‐Aptian) nonvolcanic rifting and Late Cretaceous (Turonian‐Santonian) opening of the Black Sea by the splitting of the arc are unrelated events.

Kinematic reconstructions and magmatic evolution illuminating crustal and mantle dynamics of the eastern Mediterranean region since the late Cretaceous

“…Late Cretaceous extension controlled the opening of sedimentary basins [Sunal and Tüysüz, 2002;Okay et al, 2013]. Further south, a forearc basin developed in front of a succession of S-vergent thrust units where several HP-LT metamorphic events have been recorded during the Cretaceous [Okay, 1986;Okay and Satır, 2000a;Okay et al, 2013] (figure 5). These units were subsequently exhumed as a syn-orogenic extrusion wedge, such as in the central Pontides and the Biga peninsula Beccaletto et al, 2007].…”

Thermal structure of low-grade accreted Lower Cretaceous distal turbidites, the Central Pontides, Turkey: insights for tectonic thickening of an accretionary wedge

“…The Çağlayan Formation is interpreted as synrift deposits related to the opening of the Black Sea basin (Görür, 1988;Hippolyte et al, 2010). Detrital zircons from the turbidites, however, indicate a major source area in the East European Craton and Scythian Platform north of the Black Sea implying that the Black Sea basin opened after Early Cretaceous time (Okay et al, 2013).…”

“…To the south of the Lower Cretaceous turbidites, Middle Jurassic and Cretaceous subduction-accretionary complexes, the Central Pontide Supercomplex (CPS), crop out over a large area (Figure 2; Okay et al, 2013;Marroni et al, 2014;Aygül et al, 2015a). The Cretaceous accretionary wedge consists of HP/LT metamorphic rocks of continental and oceanic origin, fore-arc deposits, and mélanges.…”

“…The oceanic unit, known as the Domuzdağ Complex, consists mainly of eclogite to blueschist facies metabasite and micaschist with serpentinites, metagabbro, metachert, and marble representing deep levels of the subduction-accretionary complexes (Tüysüz, 1990;Ustaömer and Robertson, 1993, 1999Altherr et al, 2004;Okay et al, 2006Okay et al, , 2013Aygül et al, 2015a). 40 Ar/ 39 Ar phengite ages from the Domuzdağ Complex range between 114 and 92 Ma (Okay et al, 2006(Okay et al, , 2013Aygül et al, 2015a). An associated Albian arc is reported north of the Black Sea ( Figure 1; Nikishin et al, 2015).…”

Preface

“…All types of minerals are routinely separated and sent abroad for geochronological analysis. This has become especially important with the new fast ICP-MS technique of dating zircons with İTÜ joining the explosive growth of publications on zircon ages (Akbayram, Okay, & Satır, 2013;Okay et al, 2013;Okay, Zack, Okay, & Barth, 2011 Aral Okay's work is characterised by its wide range unusual for this age. He published papers on petrology, stratigraphy, structural geology, paleontology, tectonic geomorphology and, above all, tectonics.…”