Türkiye Jeoloji Bülteni

Abstract: Kangal formation meta-clastics of Middle Devonian-Lower Carboniferous have different lithologic, textural and mineralogu: features related to sedimentary burial and thrust, from bottom to top, in the Kangal-Alacahan area. Kınalar member (slates and lessmeta-siltstone, with chlorite-mica pod) contain phyllosilicates (2M, illitelmuscovite, lib chlorite, mixed-layer paragonite-muscoviteP-M, paragonite, pyrophyllite, kaolinite/dickite, mixed-layer chlorite-vermiculite-C-V, mixed-layer chlorite-smectite-C-S), calcite,quartz, goethite and chloritoid, in order of decreasing abundance. IC values are indicative of low epizonal-high anchizonal conditions. Quartz, phyllosilicates (2Ml+lMd illitelmuscovite, kaolinite/dickite), feldspar and geothite are present in the anchimeta-sandstone and anchimeta-shale and/or slates of Bakırtepe member, which represents middle anchizone IC values. The anchimeta-shale,anchimeta-siltstone, anchimeta-limestone, anchimeta-sandstone and slates with chlorite-mica pod in the Düzce member mainly consist of phyllosilicates (2M1+Md illitelmuscovite, lib chlorite, M-P, paragonite, kaolinite/dickite, pyrophyllite, CIV, CIS), quartz, calcite and geothite. IC measurements of meta-clastics show high-grade anchizone. Höyük member is commonly composed of crystallized limestone, and rarely sandstone and shale that corresponds to low anchimetamorphic or high diagenetic degree. The unit includes calcite, quartz, phyllosilicates (illitelmuscovite, chlorite and kaoliniteldickite) and goethite. The index minerals related to thrustsuch as P-M, paragonite, pyrophyllite and chloritoid are found in the allochthonous Kangal formation that appears as an indicatorto distinguish allochthonous and autochthonous units. In addition, paragenetic relationships suggest that meta-sedimentary rocks aremetamorphosed in anticlockwise P-T-t (pressure-temperature-time) path and then clockwise P-T-t path as a result of burial and thrusttectonics, respectively. 

Abstract: The study area is located in the northwestern part of Sultandağları Massif comprising autochthonous, allocththonous and neoautochthonous units. Autochthonous units is composed of volcanosedimentary Gökoluk formation of Infracambrian age and Upper Jurassic Santas formation containing the carbonate rocks of shallow sea and overlying the former with an angular unconformity. Thedykes of Mesozoic Kocakızıl dolerite cut these formations. Tlie Upper Cambrian-Lower Ordovician Sultandede formation in conformity with Lower(?)-Middle Cambrian aged Çaltepe limestone, overlies tectonically the autochthonous units. These units are alsooverlain by the Mesozoic aged Hoyran ophiolite and Hacıalabaz limestone olistolithe. All of these sequences is covered by the Pliocene Yankkaya formation and the Quaternary alluvial deposits. The regional discordances point that Assyntic, Caledonian, Hercynian and Alpine orogenies were effective in the area. Gökoluk formation deformed by Assyntic movements and Lower Paleozoic agedsequence were effected from Hercynian and Caledonian orogenic movements. As a result of these movements, the units gained theoverlain deformative geometric forms, being undergone at least three phases of deformation (Fp F2, F3) and the metamorphism. While the third deformation phase (F3) forms the kink band, the renulation cleavages and zig-zag folds; it also deformed the lines developed in the second phase. As a result of the Alpine movements, rifting in Triassic and, nappes and thrust in Senonian were developped. Finally, the crossed block fracturings developed during the tensional and neotectonic period in Miocene were caused the Sultandağları to gain the present horst configuration of NW-SE and NNE-SSW.

Abstract: Determination of the consolidation of the Düzce clays exposed along the Gümüşova-Gerede section of the Anatolian motorwayplays an important role to assess their settlement behaviour under loads of engineering structures. For this purpose, consolidationproperties of there clay in the vicinity ofDüzce are investigated. The deepest part of the alluvial deposits at Düzce plain takes placeat the southern side of Düzce. Their thickness is about 260 m. Alluvial deposits mainly consist of clay, silty clay and clayey silts atthe central and the souter parts of the basin, while granular metarials, such as sand and gravel, become dominant at the north andnorth-east side of the plain. Based on the assessments per formed for consolidation characteristics of the clayey layers, it was cone-,luded that the upper part of these layers (up the depths of to 10 m) in the plain were over consolidated. The occurence ofov er consolidation was resulted from the movement of Düzce sedimentation basin towards south due to tectonic activity of the Düzce fault.The variation in groundwater table caused an increase in the oxidation zone and the progress of overconsolidated zones due to theeffects desiccation in the upper part of the basin.

Abstract: The Bolu tunnel, with a lenght 3250 m is going to be the longest one among the others in Turkish motorway project. The tunnelalignment passes through various lithological unit and zones of strike-slip and thrust faults. The oldest unit of the Bolu tunnel of theAnatolian motorway is the Yedigöller formation of Precambrian age composed mainly ofamphibolite, gneiss, metadiorite andmetoquartzdiorite. Tectonically overlying this unit is the Îkizoluk formation, comprizing ofpyhllite, shale, quartzite and the Çatak limestone member. Upper Cretaceous is represented by a chaotic assemblage, called the Abant complex. Elmalık granitoids have intrudedinto this assemblage in the upper/later. The end of Upper Cretaceous is represented by brecciated marbles and slates of the Atyayla formation. It is overlain by Bayramışlar formation of Paleocene-Lower Eocene, which consists of sandy limestone, calcareoussandstone and breccia. The Findicak formation is represented by sandstone, siltstone, clay stone, marl and limestone. The youngestunits of the alignment of the Bolu tunnel are the Apalar formation of Middle-Upper Eocene, which is represented by alternation ofclay, claystone, clayey limestone, gypsium and marl and the Asarsuyu formation consisting of unconsolidated sediments of Pliocene.These units were piled up within a N-S compressional regime during Late Cretaceous. In Upper Miocene epoch tlie prevailing compressional regime has changed in  which, has created when the North Anatolian Fault Zone, characterized by strike-slip faults.

Abstract: Recharge of an aquifer depends on meteorological elements, such as precipitation, temperature, evapotranspiration and aquiferproperties such as swface area, thickness, geological setting, lithological and structural features and soil cover and structural features and soil cover and vegetation. In order to estimate the amount of safe yield of an aquifer, it is necessary to determine these properties. The aim of this study, is to calculate recharge rates in the limestone aquifers by using the spring discharges and to explain the causes of different rates. In this study, infiltration rates in the Triassic aged limestone aquifers in a selected region in the southern part of Çorum are calculated by analysing the spring recession cwyes. The rates calculated, range from 35% to 62%.

Abstract: Obsidian samples from several volcanic fields located in eastern Anatolia (namely: Nemrut Dağı, Süphan Dağı, Meydan Dağı,Kars, Erzurum, Pasinler, Sarıkamış, Muş, Bingöl), have been dated by the fission track (FT) method. Geological maps showing thevolcanics studied in this work have also been compiled. These maps as well as the FT ages shown in this work (from 0.03 Ma up to6.9 Ma), represent a solid contribution towards the understanding of the obsidian bearing volcanics of eastern Anatolia. Young dates (< 1 Ma), in agreement with published measurements, were determined on the west and north coasts of Lake Van. Obsidians distributed along an ideal arc extending from NE (Kars) to SW (Bingöl) gave Upper Miocene-Pliocene ages. Two previous K-Ar agesonly were available for the latter outcrops; several of them were only very recently recognised.

Abstract: This paperdealswith asexual reproduction in the me galospheric forms of Simplorbites and Orbitoides genera. Re-evaluations of their various specimens from France and Turkey indicate an unusual asexual schizogonic reproduction. The Orbitoides specimens recently collected from Hekimhan (NWMalatya, Eastern Turkey) also supportthis type of reproduction. The exceptional reproduction on the genera can be given as follows: a) division of me galospheric embryos and formation of new embryos, b) dissolution of parental tests and movement of embryos towards periphery,, c) release of embryos; and d)formation of new periembriyonic chambers and young individuals. In this study, several lines of evidence have been presented in support of such a reproduction process.

Abstract: Niksar-Ba§çiftİik (Tokat) area, according to the variety and. the characteristics of the fauna is an important region. Measuredstratigraphy sections were done and. the foraminifera contents of the sediments in the study area were detennined; stratigraphicaldistribution of the benthic and planktic foraminifera were fixed. Kırandağ fonnation is detennined as Middle-Upper MaastrichtianDanian aged and- Düdenyayla formation is evaluated as Danian aged.