Abstract:

In central Turkey the Çankırı Basin developed between the Kırşehir and Sakarya continents as a collisional basin during the Tertiary. Along the southern border, between Yozgat and Yerköy, the basin fill predominantly comprises continental and shallow marine facies, and overlies the Late Cretaceous Kırşehir Block unconformably. The Yoncalı formation (shallow marine sandstones, shales and limestone lenses), the İncik formation (terrestrial conglomerates and sandstones) and the Bayat formation (subaerial lavas and pyroclastic rocks) are Middle to Late Eocene in age and grade laterally and vertically into each other. These units are unconformably overlain by a Middle Miocene continental sequence that is composed of terrestrial conglomerates, laminated shales and evaporites, called the "cover series". These dominantly continental sequences are generally devoid of fossils. Coal and carbonaceus shale horizons of the Çankırı Basin fill and the "cover series" were sampled and their spore and pollen associations were examined to define the palynomorph content, and determine ages and palaeoclimatic and palaeoecological conditions of the Tertiary units in the Çankırı Basin. The palynologic determinations indicate that the Yoncalı and İncik formations are of Middle-Late Eocene age and the overlying cover units of the Kızılırmak and Bozkır formations are of Middle Miocene age. In addition to sedimentologic features, the palynomorph association, observed in the Yoncalı formation, indicates that the unit was deposited in swamps between the channels of a deltaic environment. The presence, in particular, of the tropical Gleicheniaceae, Schizeaceae, Icacinaceae, Palmae and the tropical-subtropical Cyrillaceae, Simaroubaceae, Anacardiaceae, and Sapotaceae indicate a moist tropical climate during deposition of the coals and shales of the Yoncalı formation. Cupressaceae, Taxodium, Oleaceae, Nyssa, Carya, Engelhardtia, Cyrillaceae, Alnus, Ulmus and Pterocarya, observed in the Kızılırmak and Bozkır formations, indicate that the units were deposited in a lacustrine environment under subtropical climatic conditions.

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