Wkly Abstr Sanit Rep

19316974PMCnul

age, petrographical and geochemical characteristics

The Neogene tuffs of the Akkasdagi region, in the south eastern part of the Cankiri-Corum Basin in Central Anatolia, yielded one of the richest mammalian faunas of Turkey. The main aim of the present study is to provide data on the distribution, age, petrographical, mineralogical and geo-chemical composition of these tuffs. It is shown that they are primary products of a volcanic process. The Akkasdagi tuffs are included in a late Miocene sedimentary sequence and were deposited as pyroclastic flow deposits. The gas escape structures (gas segregation pipes) in tuffs and the abundance of pumice and lithic clasts in the lower parts should be mentioned. The age of the tuffs is determined as late Miocene (MN 12 zone) based on the rich mammalian fauna and as 7.1 +/- 0.1 Ma on the basis of radiometric dating. The petrographic investigations indicated that the Akkasdagi tuffs are vitric tuffs. Biotite and lithic clasts occur in a glassy matrix. In addition, they contain feldspar (orthoclase), quartz phenocrysts, oxyhornblende and pumice clasts. With these properties, the tuffs present all characteristics of ignimbrites. Geochemical analyses reveal the calc-alkaline nature and rhyolitic composition of these tuffs. These results show that the Akkasdagi tuffs show similarities to those of the Nevsehir Plateau which belong to the Central Anatolian Volcanic Province. Because these tuffs are pyroclastic flow deposits, it is thought that the source area should be close to Akkasdagi Volcanic activity might have caused the mass death of mammals the remains of which are concentrated in several bone pockets.C1 Gen Directorate Min Res & Explorat, Museum Nat Hist, TR-06520 Ankara, Turkey.Ankara Univ, Fac Engn, Dept Geol Engn, TR-06100 Ankara, Turkey.Museum Natl Hist Nat, Dept Hist Terre, CNRS, UMR 5143, F-75231 Paris 05, France.Univ Montpellier 2, CNRS, ISTEEM, UMR 5573,Lab Dynam Lithosphere, F-34095 Montpellier, France.Pamukkale Univ, Dept Geol Engn, TR-20100 Denizli, Turkey

Akkasdagi area, Turkey

The Akkasdagi area, situated in the southern margin of the Tertiary Cankiri- Corum Basin, Central Anatolia, Turkey, includes a 280 m, thick, mostly continental sediment sequence that overlies either marine Palaeogene transgressive deposits or metamorphic rocks of Kirsehir Massif. From bottom to top the sequence can be divided into units of Deliceirmak Fm. (alluvial fan deposits) and Ceritkale member (marine fan-delta and shelf carbonates) of mid-upper Eocene, Guvendik Fm. (gypsum) of Oligocene, and Akkasdagi Fm. (fine to coarse-grained alluvial clastics and lacustrine limestone) of upper Miocene-lower Pliocene. A granitic intrusion was emplaced into the basin after late Eocene. The Neogene succession includes mammalian fossils and the lithological composition of the succession is rather different from its equivalences in other parts of the basin. By facies analysis the Neogene infill could be categorised into alluvial fan deposits (facies association I), fluvial deposits (facies association II), lacustrine deposits (facies association III) and pyroclastic flow deposits (facies association IV). Facies association I is dominant and the others are observed inside as alternating sequences. The facies architecture and facies associations suggest that a structural depression existed in the area and was filled with sediments of distal alluvial fans, flood plains and lakes receiving deposits of distal or terminal alluvial fans and flood plains, and occupied partly by lakes

Akkasdagi area, Turkey

The Akkasdagi area, situated in the southern margin of the Tertiary Cankiri- Corum Basin, Central Anatolia, Turkey, includes a 280 m, thick, mostly continental sediment sequence that overlies either marine Palaeogene transgressive deposits or metamorphic rocks of Kirsehir Massif. From bottom to top the sequence can be divided into units of Deliceirmak Fm. (alluvial fan deposits) and Ceritkale member (marine fan-delta and shelf carbonates) of mid-upper Eocene, Guvendik Fm. (gypsum) of Oligocene, and Akkasdagi Fm. (fine to coarse-grained alluvial clastics and lacustrine limestone) of upper Miocene-lower Pliocene. A granitic intrusion was emplaced into the basin after late Eocene. The Neogene succession includes mammalian fossils and the lithological composition of the succession is rather different from its equivalences in other parts of the basin. By facies analysis the Neogene infill could be categorised into alluvial fan deposits (facies association I), fluvial deposits (facies association II), lacustrine deposits (facies association III) and pyroclastic flow deposits (facies association IV). Facies association I is dominant and the others are observed inside as alternating sequences. The facies architecture and facies associations suggest that a structural depression existed in the area and was filled with sediments of distal alluvial fans, flood plains and lakes receiving deposits of distal or terminal alluvial fans and flood plains, and occupied partly by lakes.C1 Ankara Univ, Fac Engn, Dept Geol Engn, Tecton Res Grp, TR-06100 Ankara, Turkey.Gebze Inst Technol, TR-41400 Gebze, Kocaeli, Turkey.Gen Directorate Mineral Res & Explorat, Museum Nat Hist, TR-06520 Ankara, Turkey.Museum Natl Hist Nat, Dept Hist Terre, CNRS, UMR 5143, F-75231 Paris 05, France.Pamukkale Univ, Dept Geol Engn, TR-20100 Denizli, Turkey

The stratigraphical position of Kemiklitepe fossil locality (Esme, Usak) revised: Implications for the Late Cenozoic sedimentary basin development and extensional tectonics in western Turkey

Unlike earlier studies attributing the Kemiklitepe fossil locality to the Inay Group, the present study indicates that it is to be assigned to the Asartepe Formation that unconformably overlying the. Inay Group. This seems to verify the early Middle Miocene age of the Inay Group, previously determined by isotopic dating and palynological analyses. However, the early Middle Miocene age and the overall undeformed nature of the Inay Group do not concur with the regional two-stage extension model proposing a compressional phase during the Miocene/Pliocene interval. The correlation of the Asartepe Formation hearing the Kemiklitepe fossil locality further to the north indicates that a NE-SW trending fault was active during the Late Miocene. Recent Studies modelling the uplift history of the region are unconvincing because they ignore Late Miocene activity on the NE-SW trending faults and assume a timing of incision of the may Group after the Late Pliocene (similar to 3Ma) in their calculations

Determining The Main Strand Of The Eskisehir Strike-Slip Fault Zone Using Subsidiary Structures And Seismicity: A Hypothesis Tested By Seismic Reflection Studies

The Eskisehir Fault Zone is one of the major neotectonic structures of Turkey, extending from Inegol (Bursa) to Cihanbeyli (Konya). The fault zone presents a considerable seismic risk for the city of Eskisehir but the exact locations of active segments and the source of the major seismic event, the 1956 earthquake (M = 6.5) that occurred in the instrumental period (from 1900 to 2013), have been debated in recent literature. The structural data obtained from field studies indicate an approximately N60W-trending main strand of the right lateral strike-slip Eskisehir Fault Zone. This trend corresponds to the en echelon bends on the course of the Sarisu River. Using this concurrence, the positions of Bahcehisar and the Cukurhisar-Sultandere segments are proposed and checked by seismic reflection studies. The seismic sections disclosing positive flower structures confirm the hypothesized position of the Cukurhisar-Sultandere segment. The relocation of epicenters and focal mechanism solutions of seismic events in 1956, 1990, 2010, and 2013 indicate that the Cukurhisar-Sultandere segment might be the rupture source of the 1956 event and is a possible potential seismic source for an earthquake that could seriously affect the Eskisehir settlement.WoSScopu