Browsing by Author "Krystyn, Leopold"

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Citation - WoS: 4
Citation - Scopus: 4
First Recovery of Late Early Triassic (spathian) Pelagic Assemblages (radiolarians and Conodonts) From Block in the Upper Karakaya Complex Near Ankara City, Central Turkey: Biostratigraphical Remarks and Correlation
(PERGAMON-ELSEVIER SCIENCE LTD, 2021) Tekin, U. Kağan; Kamata, Yoshihito; Krystyn, Leopold; Okuyucu, Cengiz; Sayit, Kaan; Nalbantlı, Mustafa
The Upper Karakaya Complex, belonging to the Karakaya Complex, includes different blocks and tectonic slices within a Triassic sheared matrix. This wide-spread unit mainly exposed in northern Turkey also crops out to the southern part of Ankara city near Gokcehuyuk village. Instead of a continuous sequence of Carboniferous to Permian age described in a previous study, five different blocks of various origins and ages are identified in this study. One of the pelagic blocks composing of cherty limestone includes radiolarian and conodont assemblages typical of Spathian age, representing the Triassospathodus homeri Conodont Zone. It corresponds also to the Hozmadia ozawai Radiolarian Zone although the zonal guide could not be obtained from the radiolarian assemblage. This is so far the first recovery of pelagic assemblages (radiolarians and conodonts) from the Karakaya Complex. This result clearly indicates that pelagic sedimentation took place in the Karakaya Complex during late Early Triassic time. Compared to previous studies, it can be stated that radiolarian cherts have been deposited in the Karakaya Complex in two different time span from Middle to Late Devonian and Late Permian (Changhsingian) to early Late Triassic (Carnian) time, respectively.
Integrated Stratigraphy (from Radiolarians, Conodonts, Palynomorphs, Ammonoids, Ostracods) of the Early Carnian Deepening Upward Sequence (the Huglu Unit) Within the Tectonic Slices/Blocks of the Mersin Mélange, Southern Turkey: Biochronologies and Paleogeographic İmplications
(2023) Tekin, Uğur Kaan; Krystyn, Leopold; Kürschner, WolfraM; Okuyucu, Cengiz; Sayit, Kan; Forel, Marie-Béatrice
The Mersin Ophiolitic Complex in southern Turkey includes two different units as the Mersin M´elange (MM) and Mersin Ophiolite with metamorphic sole and is situated to the north and northwest of Mersin City, southern Turkey. The MM is a typical sedimentary m´elange and contains slide blocks of oceanic and continental origin in a sheared and deformed olistostromal matrix of Late Cretaceous age. It has clear affinity to the allochthonous units (the BeysehirHoyran Nappes) originated from northern branch of Neo-Tethys. Two different blocks (the Tavuscayiri and the Kocatabur) are widely-exposed to the northern part of the MM. Based on detail studies on the Tavuscayiri Block, samples along the Kilek Section have been investigated and they indicate that it contains two different parts. Lower part of the section characterized the Tavuscayiri Formation is represented by an alternation of conglomerates and sandstones at the basal part and followed respectively by sandy limestones, thick-bedded to massive limestones. This succession is interpreted as deeping upward sequence from fluvial / esturaine to marine conditions. Conglomeratic Sandstones at the base of sequence yielded palynomorphs indicating basal Julian age. Due to successive drowning of platform to the top of the Tavuscayiri Formation, red pelagic limestones with ammonoid remains appear. By correlating this part to the covealant beds with abundant ammonoid taxa around the Killik Hill, its age can be assigned that late Early Carnian. Higher up-section follow the Huglu Tuffites which are carbonate-poor except for the uppermost part. Cherty limestones at the top of the exposed Huglu Tuffites include rich and diverse radiolarian fauna. Radiolarian fauna clearly reveals the late Early Carnian age corresponding to the Tetraporobrachia haeckeli Zone. This age assignment has also been confirmed by dating of associated fauna (conodont and ostracoda) obtained from adjacent beds. We interpret the marked changes in the sedimentary environment as rapid prograding deepening in a back-arc basin setting of the Izmir-Ankara Ocean culminated in the high volcanic activity of the Huglu Tuffites.
Citation - WoS: 12
Citation - Scopus: 13
Late Triassic To Early Jurassic Radiolarian, Conodont and Ammonite Assemblages From the Tavuscayiri Block, Mersin Melange, Southern Turkey: Time Constraints for the T/J Boundary and Sedimentary Evolution of the Southern Margin of the Northern Neotethys
(MUSEUM NATL HISTOIRE NATURELLE, 2020) Tekin, U. Kağan; Krystyn, Leopold; Okuyucu, Cengiz; Bedi, Yavuz; Sayit, Kaan
The Mersin Melange (northwest of Mersin city) includes a variety of large sedimentary blocks/tectonic slices of Palaeozoic and Mesozoic origins. Of these, the latter represents facial and tectonostratigraphic counterparts of the Beysehir-Hoyran Nappes (remnants of the northern Neotethys). The Tavuscayiri Block, located at the center of the melange and dose to the Orbuklukeli hill, is one of such Mesozoic occurrences, with a continuous pelagic sequence from the Upper Triassic to Lower Jurassic. At the Orbuklukeli hill, a succession of middle Norian to Toarcian age has been precisely dated, which starts with conodont assemblages for the Norian and Rhaetian and includes radiolarians for the upper Rhaetian. An acidic tuff layer corresponds to the T-J boundary, which passes above to an increasingly dominating chert-bearing limestone series, marking a gradually deepening-upward of the sequence. The early Hettangian radiolarians are poorly represented, but diverse and well-preserved radiolarians have been retrieved from the middle Hettangian to the Pliensbachian. A total of eighty-five taxa, including fourteen new species, have been determined. In addition to these, one new genus (Praeudalia Tekin, n. gen.) has been described from the Rhaetian part of the section. The top of the section is represented by nodular limestones in Ammonitico rosso facies, including a diverse Toarcian ammonite fauna. All lithologies of the Orbuklukeli section along the Tavuscayiri Block can be correlated with the previously described lithologies of the Kayabasi Group/Formation in the Bozkir Unit, and Gulbahar/Gumuslu units in the Lycian Nappes.