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Tertiary Terrestrial to Shallow Marine Deposition in Central Anatolia: A Palynological Approach

2002; Volume: 11; Issue: 2 Linguagem: Inglês

1303-619X

Funda Akgün, Erhan Akay Burhan Erdoğan,

Marine and environmental studies

In central Turkey the Cank›r› Basin developed between the K›rflehir and Sakarya continents as a collisional basin during the Tertiary. Along the southern border, between Yozgat and Yerkoy, the basin fill predominantly comprises continental and shallow marine facies, and overlies the Late Cretaceous K›rflehir Block unconformably. The Yoncal› formation (shallow marine sandstones, shales and limestone lenses), the ‹ncik 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 series. These dominantly continental sequences are generally devoid of fossils. Coal and carbonaceus shale horizons of the Cank›r› Basin fill and the 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 Cank›r› Basin. The palynologic determinations indicate that the Yoncal› and ‹ncik formations are of Middle-Late Eocene age and the overlying cover units of the K›z›l›rmak and Bozk›r formations are of Middle Miocene age. In addition to sedimentologic features, the palynomorph association, observed in the Yoncal› 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 Yoncal› formation. Cupressaceae, Taxodium, Oleaceae, Nyssa, Carya, Engelhardtia, Cyrillaceae, Alnus, Ulmus and Pterocarya, observed in the K›z›l›rmak and Bozk›r formations, indicate that the units were deposited in a lacustrine environment under subtropical climatic conditions. Orta Anadolu Tersiyer Karasal-S›¤ Denizel Tortullaflmas›: Palinolojik Bir Yaklafl›m Ozet: Orta Turkiye'de Cank›r› Havzas›, Tersiyer suresince, K›rflehir ve Sakarya k›talar› aras›nda yer alan bir carp›flma havzas› olarak flekillenmifltir. Havzan›n guney s›n›r› boyunca, Yozgat-Yerkoy aras›nda, havza dolgusu egemen olarak karasal ve s›¤ denizel fasiyestedir ve Gec Kretase yafll› K›rflehir Blou'nu uyumsuzlukla orter. Yoncal› formasyonu (s›¤ denizel kumtafllar›, seyller ve kirectafl› mercekleri), ‹ncik formasyonu (karasal konglomeralar ve kumtafllar›) ve Bayat formasyonu (karasal lavlar ve piroklastik kayalar) Orta-Gec Eosen yafll›d›r ve birbirleri ile yanal ve dufley gecifllidir. Bu birimler Ortu Serileri olarak adlanan, karasal konglomeralar, laminal› fleyller ve evaporitlerden yap›l›, Orta Miyosen karasal istifi taraf›ndan uyumsuzlukla ustlenir. Bu egemen karasal istif genellikle fosilsizdir. Bu cal›flman›n amac› Cank›r› havzas›nda Tersiyer birimlerinin yafllar›n› ve paleoklimatik ve paleoekolojik koflullar›n› saptamak ve palinomorf iceriini tan›mlamakt›r. Bu amaca ulaflmak icin, Cank›r› Havza's› tortul dolgusunun komur ve karbonlu fleyl horizonlar› ve Ortu Serileri orneklenmifl ve onlar›n spor ve pollen topluluklar› incelenmifltir. Palinolojik incelemeler, Yoncal› ve ‹ncik formasyonlar›n›n Orta-Gec Eosen, uzerleyen K›z›l›rmak ve Bozk›r formasyonlar› ortu birimlerinin ise Orta Miyosen yafll› olduunu belirtir. Sedimentolojik ozelliklerin yan›s›ra, Yoncal› formasyonundan tan›mlanm›fl olan palinomorf topluluu, bu birimin bir delta ortam›n›n kanallar› aras›daki batakl›klarda depolanm›fl olduunu tan›mlar. Ozellikle tropical Gleicheniaceae, Schizeaceae, Icacinaceae, Palmae ve tropikal-subtropikal Cyrillaceae, Simaroubaceae, Anacardiaceae ve Sapotaceae'nin varl›¤›, Yoncal› formasyonu komur ve fleyllerinin depolanmas› s›ras›nda nemli tropical bir iklimin varl›¤›n› gosterir. K›z›l›rmak ve Bozk›r formasyonlar›nda Cupressaceae, Taxodium, Oleaceae, Nyssa, Carya, Engelhardtia, Cyrillaceae, Alnus, Ulmus and Pterocarya'n›n gozlenmesi, bu birimlerin subtropikal iklim koflullar› alt›nda ve golsel ortamda depoland›¤›n› belirtir.