Türkiye Jeoloji Bülteni

Abstract: In this study, paleo geographical distribution and morphological features of Orbitoides gruenbachensis Papp in TethyanOcean is presented. The indicated species was found first time in Austria. The occurrence of Orbitoides gruenbachensis Pappin the Middle and Western parts of the Pontids and the northern part of the Helenid-Torid platforms indicates that thementioned species lived in a restricted area and preferred a shallow paleoenvironment having low salinity and temperature.Besides, its appearance in the Maastrichtian deposits both A ustria and Turkey also shows that its range has a resticted time.

Abstract: In this study, a few individuals of probably a new orbitoidal foraminiferal genus, conic flabelliforme in shape, havinghyaline calcareous wall as well as in the same wall of the concave side of the Sivasella genus and including similarchamberlets to the equatorial chambers of the Ilgazina genus are described.

Abstract: Çolaklı-Elazığ mineralizations occur as vein type fillings in the fracture zones of diorite rocks of Coniacian-Camp onionElazığ magmatites. The veins strike N10-6Ö* W and dip vertically. They extend between 250-800 meters and their thicknessesvary between 0.5-3.5 meters on the surface. The ore mineral assemblage of the veins are galena, freibergite, pyrite, cubanite,chalcopyrite, tetralxedrite, barytine and secondaiy minerals derived there. The ore is massive or disseminated within thecarbonate minerals and quartz. The chemical analysis give high Pb, Ag, Zn andSb values. Ag takes places in the structure offreibergite which itself occurs always as enclosed in galena This is well demonstrated by high A g-Pb, Cu-Sb and A g-Sbvalues (r=0.82, r=0.73 and r=0.86 resprectively).Çolaklı mineralization appears to be fowned by the late phase magmatic solutions originated from granitic intrusionswhich followed the deformation and fractiuing of the dioritic rocks. This model is supported by the presence of aplite andquartz- filled veins within the ore veins.

Abstract: This study contains the hydro geological and hydrogecohemical investigations carried out in Diyarbakır and surrounding area. Mardin formation, which is the oldest unit in the field, forms the reservoir of the oil and its production water. The overlying Gercüş formation is aquiclude, and Midyat, Germik, Şelmo formations and basalt unit are aquifers. There are anumber of contaminant sources for both surface water and groudwater in the field. Particularly, reinjection of the productionwater, extracted from the Mardin formation, to the Midyat formation that consists of karstic limestone, instead of Mardin formation, (which is the reservoir of the production water) creates a high risk for the Diyarbakır City potable water. The hydmgeochemical properties and vulnerability to contamination of the aquifers in the study area are discussed.

Abstract: A ndesitic volcanic rocks and their weathering products "clays" are highly widespread around İzmir. The materialproperties of andesites vary with their weathering grades. Smectite type clay minerals are formed in moderately andcompletely weathered andesites. The clays formed as a result of weathering are determired to have formed in two waysduring the field observations. First, the andesitic lava alters the previously flown and partially solidified andesitic lava and aresiduel clay is formed. Secondly, the andesite is weathered by groundwater circulation through the discontinuities and byatmospheric factors, produce clay and silt. The smectite type clays formed as a weathering product, swell by taking water in their structure and developed instabilities controlling by the discontinuities. This may cause slope failures even at gentleslopes along the clay-filled cooling joints.In this paper, the geomechanic test results of the clay s formed from weathering of the andesite taken from Susuzdede Park,Osmangazi, Asansör Quarry and the Nenehatun Shaft of the İzmir Metro, are presented and the influence of such soil types onthe stability of the abondoned quarries and road slopes, are discussed.

Abstract: The aim of this study is to indicate the organic geochemical characteristics of the Lower Miocene limestones. The Yazırformation contains various lithological and biofacies deposits. These are, from bottom to top, the coarse grained elastics,clayey limestones with laminated algae and miliolid, thick bedded limestones with algae and corals, clayey to sandylimestones with benthic foraminiferaThe total organic carbon content of Yazır formation is poor, but in some levels, it seems to be rich. Rare hydrocarbonoccurrences are also seen in these sections. Samples are derived from the marine organic matters (amorphous) in general.Vitrinite reflectance values range between %0.12-0.44. When these data is considered, the Yazır formation is thought to be ina diagenesis stage. When all the data are evaluated together, the Yazır formation can be regarded as a source rock for oil atsome levels. Organic geochemical and microscopic data show B organic facies according to Jones (1987) and Baskin (1997)classifications.

Abstract: Şahinkaya Member, represented by reefal limestone, of Tonya Formation is first defined as Maastrihtian-Danian aged by Korkmaz (1983). Korkmaz1 s (1983) type locality for Şahinkaya Member was not standardized. Thus, Çalköy section is chosenfor a representative type locality in this study The bottom of Şahinkaya Member is constituted by nidist- bearing biosparite,which contains Orbitoides apiculatus Schlumberger and Siderolites calcitrapoides Lamarck. The same lithology is continuingwith miliolidea, algea bryzoa-bearing intraclast sparites and passing through Caskinolina sp., Gyroidina, sp., Gyroidina sp. Anomalina sp., miliolidea, algea and bryozoa-b earing algal biosparites. At the top level section, algea-bearing biospantescontains Idalina sinjarica Grimsdale, Miscellanea sp., algae, biyzoa, annelid tubes, echinoid spine and crinoids. This facie slocally contains iron-bearing sandy limestone beds. At the top level of this unit is consisting of Discocyclina seunesi Douville. The fossil fauna above indicate that the age of Şahinkaya Member is Maastrihtian-Thanetian. K/T transition in the Eastern Pontides with benthic fauna is first defined in this study. 

Abstract: This paper concerns the neotectonics of the Bolkar Mountains, belonging to the Central Taurides in Southern CentralAnatolia. The study is based on observations on Synthetic Aperture Radar (SAR) scenes of the European Remote Sensing(ERS) satellite and Digital Elevation Model (DEM images, complemented with field structural analysis. Il is revealed thatextensional tectonics prevails in the area during the Neogene. In the northern sector, movements trend west and are attributedto the westward escape of Anatolia towards the Aegean basin. Further south, movements turn progressively to the southwestthen south and are related to the opening of the Adana-Cilicia basin probably as early as the Late Oligocene-Early Miocene.More importantly, uplift of the Bolkar Mountains occured in the Neogene coeval with this extension. The belt is interpreted asthe northern uplifted shoulder of the Adana-Cilicia basin, due to thermal effects of Neogene lithospheric stretching and thinning. This is the consequence of the inception of a backward and downward retreat of the African subducting slab beneathCyprus in the Late Oligocene-Early Miocene, which has resulted in a wide extension in the overriding plate. Transition between high elevations in the Central Taurides and deep bathymetry in the Cilicia basin suggests that gravitational forces mayalso contribute to the extension during the Neogene-Quaternary. 

Abstract: Aluminum sulfate minerals, kaolin and bentonitic clay deposits and zeolites occur within upper Miocene-Pliocene high-Kandesitic-dacitic volcanic rocks and lacustrine sediments in the west southwest of Konya, Turkey. In the area, post-volcanic phenomena, such as solfatara activity, has already been continued.The samples taken from the study area were mineralogically and chemically examined using XRD, SEM-EDS, XRF,AAS, DTA-TG and microprobe instruments. As a result of this investigation, it has been determined that alteration mineralsformed by early-and/or post volcanic acid solutions reacted with the solutions were highly acidic in character, alunite and natroalunite were produced by the alteration of mainly dacitic volcanic rocks, while minamiite was formed by the alteration ofandesitic volcanic rocks. However, acidic or weakly acidic solutions yielded kaolinite and/or halloysite and illite.Alunite group minerals are K, Na and Ca sulfate with formula (Ca, Na, K) A13(SO4) 2 (OH) 6 and mainly form as hydrothermal minerals in the study area. Nearly pure minamiite and alunite have been found in a few samples. They are commonly associated with silica polymorphs, kaolinite and halloysite in various parts of the study area.Stability relations of minerals in the advanced argillic alteration zone indicate alteration took place under acidic conditionsin the near-surface environment. Mineralogical and textural evidence also suggests alteration occurred in steam-heated environment, rather in a supergene or magmatic hydrothermal origin.

Abstract: The Late Cenozoic sediments in the surroundings of Söke are assigned to the Late Early Miocene and Quaternary on thebasis of small mammals from the Söke, Dededağ and Savulca formations. The Söke fauna from the Söke Formation and theDededağ fauna from the Dededağ Formation are correlated with the Orleanian (Late Early Miocene) and theMN4 mammalzone. The Kemalpaşa Mahallesi-I and the Kemalpaşa Mahallesi-II faunules from the Savulca Formation suggest EarlyBiharian (Early Pleistocene) and Toringian (Middle-Late Pleistocene) ages, respectively. The Burçaktepe fauna indicates aLate Early Biharian-Recent age. In the Söke fauna, a new species-A Ibertona aegeensis-is described.

Abstract: Başnayayla molybdenum-copper mineralization is related to granitic rocks ofPaleocene age (?) which are located on thenorthern edge of the Central Anotalian Crystalline Complex and Kırşehir Massif, approximately 15 km southwest of Yozgat district The rock units around the mineralization are; Kamışcıdere gabbro, Başnayayla granitoid, Beşiktepe volkanosedimentary series and alluvium. Başnayayla granitoid consists of biotite granite, microcline granite, andalusite-sillimanitegranite ve two mica granite together with felsic dikes. Kamışcıdere gabbro and Başnayayla granitoid are cut by felsic andmafic veins. Molybdenum-copper mineralization is hosted by biotit granite, andalusite-sillimanite granite and two mica granite with cordierite granite, aplite granite and quartz veins of the Başnayayla granitoid surrounded by Kamışcıdere gabbro andBeşiktepe volkano-sedimentary series Molybdenum mineralizations are occured as molybdenite-bearing quartz veins/veinlets, coatings in joints and cracks and,disseminations in the host rock. Main ore minerals are molybdenite, pyrite, chalcopyrite and magnetite. Cubanite, pyrrhotite,sphalerite, galena, ilmenite, bornite and bismuthinite are also encountered in traces. Limonite, hematite, marcasite, chalcociteand covellite are occured as secondary minerals. Three types of alterations related to the mineralization were determined andthese are quartz+s e ricite+py rite, quartz+feldspar+biotite and quartz+feldspar+biotite+sericite/muskovite associations. Molybdenum mineralization is generally seen between quartz+sericite+pyrite and quartz+feldspar+biotite alteration zones andwithin quartz+feldspar+biotite alteration zone.The mineralizations my be defined as low-grade porphyry and/or stockwork molybdenum-copper type when the ore types,mineralogy and alteration properties are taken in account. Başnayayla granitoid which involves Başnayayla porphyry and stockwork molybdenum-copper mineralization posseses the different properties than those of the host rocks mentioned in theliterature from the points of origin and geotectonic environments. On the basis of mineralogical, petrographical andgeochemical data, although it has the properties of 1- and S-type granites, the properties of the S-type is dominant in theBaşnayayla granitoid. From the geotectonic environments point of view, the Başnayayla granitoid possesses the features of thesy n-co His ional granites.