Abstract The Sakarya Zone and the Kırşehir Block of northern Turkey are separated by the İzmir–Ankara–Erzincan Suture (IAES) Zone which is the remnant of the northern branch of the Neotethys Ocean. During the closure of the IAES in the Late Cretaceous, northwards drift of the Kırşehir Block and its eventual indentation into the Sakarya Zone produced crustal deformation defined by thrusts and reverse faults, mainly between the indenting Kırşehir Block and the Sakarya Zone. Previous palaeomagnetic studies in the eastern part of the Pontides and the Sakarya Zone showed that palaeomagnetic declinations could record the deformation that resulted in the curvature of the IAES. In order to define the tectonic deformation of the northern part of the Kırşehir Block, we present new palaeomagnetic data from 57 different sites that include Mesozoic–Cenozoic sedimentary and volcanic rocks. The results from Late Cretaceous rocks (40 sites) indicate that large clockwise rotations of c. 140–165° occurred in the eastern limb of the bend, while anticlockwise rotations progressively decreased from c. 80° to 55° from SW to NW in the western limb of the bend. In contrast, small clockwise and anticlockwise rotations are observed in the flat-lying segment of the suture zone. These rotation patterns are consistent with the geometrical trends of the IAES in northern Turkey. Declinations of seven different Middle Eocene sites within the Kırşehir Block are rotated anticlockwise by c. 30–10°. This indicates that the deformation in the Sakarya Zone and the Kırşehir Block continued in the Middle Eocene.

The volcanic basement of the Ecuadorian Western Cordillera (Pallatanga Formation and San Juan unit) is made up of mafic and ultramafic rocks that once formed an oceanic plateau. Radiometric ages from these rocks overlap with a hornblende 40 Ar/ 39 Ar plateau age of 88 ± 1.6 Ma obtained for oceanic plateau basement rocks of the Piñon Formation in coastal Ecuador, and with ca. 92–88 Ma ages reported for oceanic plateau sequences in the Caribbean and western Colombia. These results suggest that the oceanic plateau rocks of the Western Cordillera and flat forearc in Ecuador are derived from the Late Cretaceous Caribbean-Colombia oceanic plateau. Intraoceanic island-arc sequences (Rio Cala Group) overlie the plateau in the Western Cordillera and yield crystallization ages that range between ca. 85 and 72 Ma. The geochemistry and radiometric ages of island-arc lavas from the Rio Cala Group, combined with the age range and geochemistry of their turbiditic, volcaniclastic products, indicate that the arc was initiated by westward subduction beneath the Caribbean Plateau. They are coeval with island-arc rocks of coastal Ecuador (Las Orquideas, San Lorenzo, and Cayo Formations) and Colombia (Ricaurte Arc). These island-arc units may be related to the Late Cretaceous Great Arc of the Caribbean. Paleomagnetic analyses of volcanic rocks of the Piñon and San Lorenzo Formations of the southern external forearc show that they erupted at equatorial or low southern latitudes. The initial collision between South America and the Caribbean-Colombia oceanic plateau caused rock uplift and exhumation (>1 km/m.y.) within the continental margin during the Late Cretaceous (ca. 75–65 Ma). Magmatism associated with the Campanian–early Maastrichtian Rio Cala Arc ceased during the Maastrichtian because the collision event blocked the subduction zone below the oceanic plateau. Paleomagnetic data from basement and sedimentary cover rocks in the coastal forearc reveal 20°–50° of clockwise rotation during the Campanian, which was synchronous with the collision of the oceanic plateau and arc sequence with South America. East-dipping subduction beneath the accreted oceanic plateau formed the latest Maastrichtian to early Paleogene (ca. 60 Ma) Silante volcanic arc, which was deposited in a terrestrial environment. Subsequently, Paleocene to Eocene volcanic rocks of the Macuchi unit were deposited, and these probably represent a continuation of the Silante arc. This submarine volcanism was coeval with the deposition of siliciclastic rocks of the Angamarca Group, which were mainly derived from the emerging Eastern Cordillera.