Aral İ. Okay1, İzver Tansel2, Okan Tüysüz1
1Eurasian Institute of Earth Sciences, Istanbul Technical University, Ayazaga, 80626, Istanbul, Turkey
2Department of Geology, İstanbul University, Avcılar 34850, İstanbul, Turkey
Tóm tắt
Late Cretaceous–Early Eocene Tethyan evolution of western Turkey is characterized by
ophiolite obduction, high-pressure/low-temperature metamorphism, subduction, arc magmatism and
continent–continent collision. The imprints of these events in the Upper Cretaceous–Lower Eocene
sedimentary record of western Anatolia are studied in thirty-eight well-described stratigraphic sections.
During the Late Cretaceous period, western Turkey consisted of two continents, the Pontides in
the north and the Anatolide-Taurides in the south. These continental masses were separated by the
İzmir-Ankara Neo-Tethyan ocean. During the convergence the Pontides formed the upper plate, the
Anatolide-Taurides the lower plate. The arc magmatism in the Pontides along the Black Sea coast is
biostratigraphically tightly constrained in time between the late Turonian and latest Campanian.
Ophiolite obduction over the passive margin of the Anatolide-Tauride Block started in the Santonian
soon after the inception of subduction in the Turonian. As a result, large areas of the Anatolide-Tauride
Block subsided and became a region of pelagic carbonate sedimentation during the
Campanian. The leading margin of the Anatolide-Tauride Block was buried deeply and was deformed
and metamorphosed to blueschist facies during Campanian times. The Campanian arc
volcanic rocks in the Pontides are conformably overlain by shaley limestone of Maastrichtian–Palaeocene
age. However, Maastrichtian sedimentary sequences north of the Tethyan suture are of
fore-arc type suggesting that although arc magmatism ceased by the end of the Campanian age,
continent–continent collision was delayed until Palaeocene time, when there was a change from marine to
continental sedimentation in the fore-arc basins. The interval between the end of the arc magmatism
and continent–continent collision may have been related to a northward jump of the subduction zone
at the end of Campanian time, or to continued obduction during the Maastrichtian.
