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    Facies characteristics of Jurassic-Lower Cretaceous successions at Kosrelik-KosrelikA +/- zA +/- gA +/- (North of Ankara, Turkey)
    (SPRINGER, 2018) Delikan, Arif; Atasagun, Nesrin
    Jurassic-Lower Cretaceous rocks in the Kosrelik and KosrelikA +/- zA +/- k areas (North of Ankara, Central Turkey) which were deposited in a tectonically controlled basin have outcrops in a very restricted area but they carry very important evidences for elucidating the Late Jurassic paleogeography of the Ankara region subjected to heavy tectonic activities during Hettangian-Oxfordian, especially during Sinemurian. Detailed facies analysis of sequences in the study area indicates that the deposition took place in two different tectonically controlled depositional settings, 3 km apart from each other. At the east of the study area, the succession is represented by Hettangian-Sinemurian aged basin sediments lying on the basement rocks with angular unconformity, but succession at the west comprises sediments of Oxfordian pelagic carbonate platform (PCP) overlying the basement rocks with angular unconformity. The PCP sediments were overlapped by radiolaria bearing pelagic limestone, Oxfordian-early Cretaceous in age, under relatively calm environmental conditions. Anomalies in C and O isotopes, trace elements and rare earth element values coincide with the periods of fast changes in the environmental conditions. The sedimentological and geochemical data indicated that the area was deepened and shallowed several times until early Cretaceous.
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    Stratigraphic and Sedimentological Characteristics of Jurassic-Lower Cretaceous Sediments at Kosrelik-Kosrelikizigi (North of Ankara, Turkey)
    (SPRINGER INT PUBLISHING AG, 2014) Delikan, Arif; Atasagun, Nesrin
    Jurassic-Lower Cretaceous rocks to the northeast of Ankara (central Turkey) were deposited in a tectonically controlled basin that was aligned SW-NE. Vertical and lateral lithological variations in the sequence resulted from synsedimentary tectonism. The Jurassic-Lower Cretaceous sequence in the study area overlies the weakly metamorphosed Late Triassic rocks (the Karakaya Complex) with an angular unconformity. The sequence begins with interbedded deltaic conglomerate and sandstone (the Corakliktepe Member). The Sinemurian-lower Pliensbachian sandy limestone overlies the coarse sandstone with both a lateral and vertical transition. The sandy limestone is red in colour and highly fossiliferous. Crinoidal limestone and ammonite-bearing marl rest on the sandy limestone, signifying a rapidly deepening depositional environment. It is overlain by red marl containing brachiopods and bivalve coquina interbeds. The intermediately bedded pseudonodular limestone with abundant ammonites, crinoids, brachiopods, and bivalves is found above the red marl. Following synsedimentary tectonism, thick nonfossiliferous mudstone was deposited over the ammonitebearing rocks (the Uzundere Member), indicating that the area shallowed during the early Pliensbachian. During the late Pliensbachian-early Toarcian, detritic rocks were deposited followed by a progressive change to deposition of variegated red limestone. This typical ammonitico-rosso facies wedges laterally into green mudstone (the Beytepe Member). After the Bajocian, the area rapidly shallowed and thick interbedded sandstone and mudstone (the Turnacesme Member) were deposited over the entire basin. Due to post-Callovian block faulting in the area, the base topography of the basin was changed. For that reason, in the northern part of the study area, the pelagic carbonate platform sediments (the Cakirlardere Formation) containing abundant ammonite and pelagic oolite were deposited directly onto the basement rocks. This points to the development of shallow areas offshore as a result of synsedimentary faulting. The pelagic ooid-bearing limestone grades laterally and vertically into cherty limestone. During the Oxfordian-Early Cretaceous, the area deepened and limestone with Radiolaria (the Sogukcam Formation) was deposited.