Fingerprints of the opening of the Western Black Sea Basin and collision of Pontides and
Sakarya Continent along the Intra-Pontide suture can be traced in the area between Cide
(Kastamonu) and Kurucaşile (Bartin) in northern Turkey, along the southern coast of the Black Sea.
The Western Black Sea Basin is an oceanic basin opened as a back-arc basin of the northward-subducting
Intra-Pontide Ocean. Basement units related to this opening are represented by Lower
Cretaceous and older units. The first arc magmatism related to this subduction began during Turonian
times. Coeval with this magmatism, back-arc extension affected the region and caused development of
horst-graben topography. This extensional period resulted in the break-up of continental crust and the
oceanic spreading in the Western Black Sea Basin during Late Santonian times. During the Late
Campanian–Early Maastrichtian period, the Sakarya Continent and Pontides collided and arc
magmatism on the Pontides ended. After this collision, the Western Pontides thickened, imbricated
and developed a mainly N-vergent foreland fold and thrust belt character since Late
Eocene–Oligocene times. The palaeostress directions calculated from thrust faults of this foreland fold and
thrust belt are 4.6°/156.6° for σ1, 6.4°/66.1° for σ2, and
83.2°/261.9° for σ3. The nature of the imbrication
indicates that it was a northward prograding foreland system connected to a floor thrust (detachment)
fault at the bottom. Field observations on curved slickenfibres support the theory that the thrust
faults of this imbricated structure have transformed to oblique thrusts and strike-slip faults over time.