Preliminary radiolarian biostratigraphy across the Jurassic Cretaceous boundary from Northwestern Turkey

Mekik, Figen
Lıng, H Yi
Altıner, Sevinç
Altıner, Demir
This is the first study from Turkey where radiolarians from calcareous sequences of the Sakarya Continent are tested in the delineation of the Jurassic-Cretaceous boundary. The Sakarya Continent, which comprises the southern part of northwest Turkey, was a Jurassic-Early Cretaceous carbonate platform micro-continent distant from terrestrial sediment influx. It was a site of pelagic carbonate deposition with abundant calcareous and siliceous microfossil input. Among 44 measured stratigraphic sections of the JurassicLower Cretaceous deposits of the Sakarya Continent, four continuous sections (MK, KEL, AC, CD) which encompass the Tithonian-Berriasian boundary were selected for study. However, due to poor preservation and calcification of radiolarian faunas, only section KEL produced rich and wellpreserved radiolarians. This section is 600 meters in thickness and spans the upper Tithonian-lower Berriasian interval. In addition to radiolarians, section KEL contains abundant calpionellids, calcareous nannofossils, benthic foraminifera and calcareous algae. The upper part of this stratigraphic section is made up of the Sogukcam Limestone which lithologically resembles the Biancone and Maiolica formations in the Umbria-Marche Region of Italy. The best preservation and richest radiolarian faunas were observed from the Sogukcam Limestone in section KEL. This is significant because many radiolarian studies as well as studies on magnetostratigraphy, calcareous nannofossils and calpionellid biostratigraphy in the Terhyan realm have been carried our on the Biancone and Maiolica formations. The rapid sedimentation rate, pelagic microfacies and well preserved non-calcified radiolarian faunas make section KEL ideal for the investigation of the Jurassic-Cretaceous boundary with radiolarians. The correlation between radiolarian faunas and co-occurring calpionellids and calcareous nannofossils in section KEL can be compared with similar biostratigraphic studies from the Biancone and Maiolica formations in Italy. The calcareous nannofossils in section KEL sometimes attain rock forming abundance, and the first appearance of nannoconids as well as their first abundance peak are recognized in this section. Throughout the present study, the boundary between Calpionellid standard zones A and B is considered as the Tithonian-Berriasian boundary. The close sampling interval, 15-20 meters, provides excellent resolution in documenting the first occurrences of numerous Cretaceous radiolarian species. These first occurrence datum points for radiolarian taxa are not concurrent. Due to the refined resolution of dating, a stepwise appearance of Cretaceous radiolarian faunas in section KEL is clearly observed; however, radiolarians do not delineate the Jurassic-Cretaceous boundary because a marked synchronous faunal turnover does not exist.


Responses of the planktonic foraminifera to environmental conditions across the cretaceous/paleogene boundary in the Göynük basin, Northwest Anatolia, Turkey
Özder, Rengin; Özkan Altıner, Sevinç.; Department of Geological Engineering (2019)
The aim of this study is to reveal the evolutionary response of the planktonic foraminifera after the Cretaceous/Paleogene (K/Pg) boundary interval in the Göynük Basin, Northwest Anatolia, Turkey. To achieve this purpose, a multidisciplinary study including biostratigraphy and mineralogy was carried out. In the Göynük area, an 8.55 m-thick section was measured, and a total of 47 samples were collected from the Seben Formation and the Hisarözü member of this formation composed of marls and clayey limestones....
The Jurassic Cretaceous Boundary in marine sedimentary successions in Turkey: a review
Yılmaz, İsmail Ömer (2018-12-07)
Microfacies and high resolution studies at the Kurovice quarry (Czech Republic, Outer Western Carpathians) on calpionellids, calcareous and non-calcareous dinoflagellate cysts, sporomorphs and calcareous nannofossils, aligned with paleomagnetism, allow construction of a detailed stratigraphy and paleoenvironmental interpretation across the Jurassic/Cretaceous (J/K) boundary. The Kurovice section consists of allodapic and micrite limestones and marlstones. Identified standard microfacies types SMF 2, SMF ...
Upper Cretaceous planktonic foraminiferal biostratigraphy from NW Turkey calibration of the stratigraphic ranges of larger benthonic foraminifera
Altıner, Sevinç (1999-01-01)
Planktonic and larger benthonic foraminifers of the Upper Cretaceous (Santonian-Maastrichtian)-Lower Tertiary (Danian) rock units from north, northwest and central Anatolian fore-are basins have been investigated in order to improve the biostratigraphic resolution of this time interval. Total abundance and diversity of planktonic foraminifers vary from rare (the sequence from the Haymana region) to high (the sequences from the Cide, Caycuma, Hanonu and Yenikonak regions) and preservation is poor to moderate...
An approach to paleoclimatic conditions for Devonian (upper Lochkovian and middle Givetian) ironstone formation, NW Anatolian carbonate platform
Yılmaz, İsmail Ömer; Göncüoğlu, Mehmet Cemal (2015-01-01)
Lower-middle Devonian iron-bearing successions were studied along 2 measured stratigraphic sections in the Camdag region of NW Anatolia. Ironstones in the upper part of the Findikli Formation in Kabalakdere are characterized by alternating red and green mudstones and sandstones at the bottom, followed by a series of dolomite, dolomitic limestone with oolitic ironstones, and chamositic mudstones at the top. Conodonts from these carbonates indicate the delta-pesavis zones of the late Lochkovian. The 12-to 45-...
The Jurassic-Early Cretaceous basalt-chert association in the ophiolites of the Ankara Melange, east of Ankara, Turkey: age and geochemistry
Bortolotti, Valerio; Chiari, Marco; Göncüoğlu, Mehmet Cemal; Principi, Gianfranco; Saccani, Emilio; TEKİN, UĞUR KAĞAN; Tassinari, Renzo (2018-02-01)
This study is focused on slide blocks including oceanic lavas associated with pelagic sediments within the eastern part of the Ankara Melange. A detailed petrological characterization of the volcanic rocks and a detailed biochronological investigation of the associated radiolarian cherts in eight sections (east of Ankara) was carried out. The volcanic rocks are largely represented by basalts and minor ferrobasalts and trachytes. They show different geochemical affinities and overlapping ages including: (a) ...
Citation Formats
F. Mekik, H. Y. Lıng, S. Altıner, and D. Altıner, “Preliminary radiolarian biostratigraphy across the Jurassic Cretaceous boundary from Northwestern Turkey,” Geodiversitas, pp. 715–738, 1999, Accessed: 00, 2021. [Online]. Available: