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

2013-09-01
Okay, Aral
Sunal, Gursel
Sherlock, Sarah
Altıner, Demir
Tuysuz, Okan
Kylander-Clark, Andrew R. C.
Aygel, Mesut
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.