LEE- Yer Sistem Bilimi Lisansüstü Programı

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http://hdl.handle.net/11527/19499

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Yazar "Erdal, Ozan" ile LEE- Yer Sistem Bilimi Lisansüstü Programı'a göz atma
  • Öge
    Systematics and biostratigraphic implications of micromammals (Rodentia) from selected pliocene-quaternary basins along the North Anatolian Fault Zone
    (Graduate School, 2023-07-20) Erdal, Ozan ; Dalfes, H. Nüzhet ; Şen, Şevket ; 601122006 ; Earth System Sciences
    Anatolia plays an important role as a bridge between Africa, Europe and Asia for the evolutionary course of vertebrates. It is potentially rich in fossil bearing deposits which would greatly serve to contribute the understanding of vertebrate evolution. However, paleontological research conducted in Turkey is mainly focused on Paleogene and Miocene deposits. Although it is obvious that any studies of mammalian paleontology dealing with any interval of Cenozoic in Anatolia is worthful because of its potential, one must point out that Quaternary mammalian fauna is still not well known when compared to European equivalent. In this manner, it is not difficult to estimate how micromammalian paleontology is less dealt. The introduction of the present thesis deals with some general definitions and fields of application of micromammals besides a brief summary of all conducted or ongoing studies on the Quaternary micromammalian fauna in Anatolia. One of the main motivations of this study is to underline the potential contribution of micromammal paleontology to Quaternary research in Turkey. On the following sections, a detailed study is provided on rodent remains which were collected from diverse localities in three adjacent basins on the North Anatolian Fault Zone (NAFZ), the depositional ages of which are estimated spanning from the Pliocene to the late Pleistocene. I investigated small mammal faunas of these basins by means of systematic paleontology, biochronology with proper stratigraphic positions, and studied their inference on paleoclimate and paleoenvironment of the localities. The North Anatolian Fault Zone (NAFZ) forms the boundary between the Anatolian and Eurasian plates and hosts many tectonic basins. The chronology of the NAFZ basin deposits is established mostly by pollen and partly by mammalian fauna studies. Nonetheless, the formation history of these basins starting in the Late Miocene to the Pleistocene and actively continuing today is still incompletely known because biochronological data are still scarce. The previous studies on the Tosya Basin by many authors and on its several aspects revealed detailed information on the structure of the basin (Barka and Hancock, 1984; Şengör et al, 1985; Andrieux et al, 1995; Dhont et al, 1998). The earliest deposition within the basin, the Devrez Formation, is claimed to date of Early-Middle Miocene but no fossil findings are discovered so far. According to Ünay and de Bruijn (1998), the only paleontological work on the area despite the lack of stratigraphic position nor systematic description, an Early Pliocene age (late Ruscinian-MN15) is suggested based on micromammal fauna from one locality at Ortalıca Village. In the same study, they proposed Early Pleistocene (MN17) age for a locality at Karasapaca Village to the West of Ortalıca, based on micromammal remains. Unfortunately, stratigraphic positions of these localities are uncertain. In the present study, the occurrence of Mimomys cf. polonicus at the Sapaca locality points out the early late Villanyian (MN16b) age for the locality which is older than previously studied locality Karasapaca by Ünay and de Bruijn (1998), situated at the north-eastern to the Sapaca village. At the Ortalıca locality, the co-occurence of Pliomys destinatus, Apodemus atavus and Mesocricetus primitivus within their stratigraphic position, supports rather the transition from MN15 (late Ruscinian) to early Villanyian (MN16a), slightly younger than age proposed by Ünay and de Bruijn (1998). On the other hand, the newly discovered Kumkapı locality, at the SW of Ortalıca and Sapaca-Karasapaca, surprisingly indicates a much younger age, late Toringian with remains of Microtus (M.) arvalis and Mus cf. macedonicus which provide a profile well younger than the Umurlu locality findings from the Niksar Basin. Finally, the finding in this basin reveals a more or less continuous deposition, where the faunal succession from the Early Pliocene (MN15) toward the Late Pleistocene follows the opening of the basin in a NE–SW direction, in almost 4 Ma. Indeed, the surprising young age of Kumkapı deposits is subjected to further geological studies in the near future. The abundance of Pliomys and Apodemus species in Ortalıca, in overall, points out rather forested, wooded and humid environment rather than grassland. (Sen, 1977; Suata-Alpaslan, 2010; Hoek Ostende et al. 2015b; Popov, 2018). However, the presence of Mesocricetus remains together with Pliomys and Apodemus would indicate that for a while between MN15b–MN16a (Pliocene), there have been cooler climatic conditions occurred, which resulted in steppe environment (Sen, 1977; Hoek Ostende et al. 2015a; Popov, 2018) may be with sparse forested area for the food sources. Sapaca locality which is younger than Ortalıca but much older than the Kumkapı localities yielded only Mimomys species, which are generally reported from relatively warm and arid, open steppe environment (e.g. Rabeder, 1981; Montuire et al, 1994; Popov, 2017). Finally, the Kumkapı locality with the presence of recent species of Microtus and Mus, is not much different from the present climate and environmental condition of the studied area such as mixture of open environment with meadows and grasslands with warm climate, as pointed out in previous studies (e.g. Montuire et al, 1994; Çolak et al, 2016; Erdal et al, 2018, 2019). The Suluova Basin is a prominent member of a wide transtensional Amasya Shear zone, located at the central part of the North Anatolian Shear Zone. Analysis of detailed stratigraphic sections, faulting data and mammal paleontology reveals that the Suluova Basin has started to evolve as a closed half-graben along the NE-SW trending, SW dipping basin bounding fault zone with normal slip at early Quaternary. Within this tectonic environment, the sedimentary assemblages were various facies of a river dominated alluvial fan network. As faults propagated westwards, the basin deepened and a fresh water lake started to develop at the basin depocenter. The initiation of E-W trending southern tectonic boundary of the basin caused further extension. Each basin boundary fault zones witnessed clockwise rotation in time. Marking an increasing water income, the Suluova Basin has evolved into a vast fresh water lake during the Middle Pleistocene (~1.7–0.8 Ma) acting as a refugia for a potential rich faunal assemblage of large and small land mammals. Thus far, micro- and macromammal remains studied from several localities in the basin comprise Kalymnomys sp. and Sivatherium sp. from late Villanyian of Kurnaz; Microtus (Allophaiomys) aff. nutiensis, Mimomys aff. pliocaenicus and Apodemus cf. dominans from late Villanyian–early Biharian of Kerimoğlu; Mesocricetus aff. arameus from early Biharian of Kızıleğrek, and Mesocricetus cf. brandti and Arvicola cf. mosbachensis from early Toringian of Yolpınar, in addition to some fragments of Equus sp. The faunal association from five localities would allow to make some assumptions concerning the past environment. For instance, the paleoenvironment of Sivatherium is reported as grasslands and well-watered landscape with much warmer temperature for the early part of Early Pleistocene (MN17–MNQ18); Kalymnomys on the other hand, is not well known but based on actual relatives (e.g., Lagurus lagurus) it is thought that should be rather dry steppe environments (Alçiçek et al, 2017, p.242). The floodplain deposits at the Kurnaz locality would support the former hypothesis in addition to environmental changes with the presence of a paleolake at the younger Kerimoğlu locality which would point out rather warmer climate. The Kerimoğlu locality, as it is important for the formation of a paleolake which is also supported by the remains of unidentified fossil fish teeth, represents an environment surrounded with deciduous woodland and bushy vegetation covers with streams and marsh-like areas by the presence of a large vole Mimomys aff. pliocaenicus and Apodemus cf. dominans. (Siori and Sala 2007; Hoek Ostende et al, 2015a; Erdal et al, 2018; Sen et al, 2018). The macromammal remains at Kamışlı has been previously reported by Sickenberg and Tobien (1971, p.60–61) where faunal elements including Equus sp. point out steppe environment crossed by forest along the water courses and lakes. The presence of Mesocricetus spp. at Kızıleğrek and Yolpınar localities would indicate somewhat dry, semi-arid steppes covered by sparse vegetation (Krystufek and Vohralik 2009). Note that Anatolia is playing an important role for the evolution of the hamster Mesocricetus during the Middle Pleistocene, which is favoured by alternating dry periods and spreading lakes causing steppe-corridors for hamsters' dispersals and adaptations (Neumann et al, 2017). On the other hand, the water vole Arvicola findings together with Mesocricetus as at the Niksar Basin, demonstrate rather a mixture of steppe-like environments with water streams for that youngest locality to the east of the Suluova Basin. A new micromammalian faunal assemblage from four horizons at the Umurlu locality (Niksar Basin, Tokat-Turkey) has been investigated; it improves our knowledge about the chronology of this basin infill. According to the stratigraphic range of the recorded species (Mesocricetus cf. brandti, Cricetulus migratorius, Arvicola cf. mosbachensis, Microtus arvalis, M. (Terricola) subterraneus, Clethrionomys cf. glareolus, Apodemus flavicollis, Nannospalax cf. xanthodon) the age of the deposit is constrained between early Middle Pleistocene and Late Pleistocene (i.e., 480–130 ka). The fossil assemblage indicates a mixture of open environments with meadows and grasslands associated with forested and bushy vegetation covers. This fauna and the implied environment are typical for an interglacial period, most probably within the interval of MIS 12–5. The studied rodent assemblage with elements of several paleobiogeographic affinities shows once more the key position of Anatolia as a bridge between the Old World continents. It improves our knowledge on Quaternary micromammals of Anatolia, which is still poorly documented, and provides a well-constrained age of the investigated localities.