Türkiye Jeoloji Bülteni

Abstract: The clinoptilolite - rich upper tuffs of Bigadiç area are in the form of coarse grained glassy as tuffs at thebottom and fine grained dust tuffs on the top. The framework structures of natural clinoptilolites taken from this both formation have been characterized by means of high - resolution solid - state nuclear magnetic resonans (NMR). The results of 29Si and 27A1 - MAS NMR studies of these samples have been compared with the data for various natural clinoptiloties. It is seen that they differ from the data of heulandite.

Abstract: This paper is concerned with the stratigraphy of autochthonous (? parautochthonous) metamoiphic rocksof the Bozdağlar massif and its unmetamorphosed cover units, in northwest of Konya.The Upper Permian - Lower Cretaceous Gökçeyurt group, which is obducted by Mesozoic Ladik metamorphitesin the study area, is the autochthonous/parautochthonous assemblage of the massif. The group consists mainly oflower - grade metamorphic rocks originally representing shallow - marine environment and is herein subdivided in three formations which are gradational to one another. These are, in ascending order, (1) The Upper Permian Derbentformation composed of metecarbonate, metaquartzite and phyllite, (2) The Upper Permian - Upper Triassic Aladağ formation consisting of alternation of metaconglomerate, metasandstone, phyllite and metacarbonate with exotic metacarbonate blocks and rare metabazite intercalations, and (3) The Upper Triassic - Lower Cretaceous Lorasdağı formationwhich is made up of a thick sequence o metacarbonate rocks with a few interbeds o metachert.The Upper Miocene - Lower Pliocene Dilekçi group consisting of alluvial fan, lacustrine and volcanic rocks, TheUpper Pliocene - Quaternary alluvial complex of Topraklı formation and Recent alluvia unconformably rest on theolder units and form the cover rocks of the massif.

Abstract: Şaplıca alunite deposit is located near the Şebinkarahisar town (Giresun) within Pontide belk Alunite mineralization exists at the vicinity of the vein type sulfide deposits. Alunite deposit and part of sulfide veins occur in intensly alterated volcanites of late Cretaceous. The alunite deposit is exclusively confined by the volcanites. Alunite mineralization is controlled by E - W and NE - SW trending normal faults which are barren. They form the channel - wayof H2SO4 rich magmatic hydrothermal fluids. Alunites are produced by the base leaching of phenocrysts (typically alkali feldspar) of rhyolitic and rhyodacitic host rocks. Alunite minerals typically occur as aggregates of bladed or lathlikecrystals up to 1 mm. long, replacing alkali feldspar and groundmass, intergrown with quartz. Alunite is locally abundantin the centre of the advanced argillic alteration zones which develop throughout the late Cretaceous volcanites. As thealunite zone develops vertically downward, advanced argillic alteration zone develops laterally outward from the aluniteborder. Kaolinite is the dominant clay mineral of this extensive alteration type. The alunite zone is ringed by kaolinite zone. The acid sulfate alteration is typically characterized by a mineral assemblage of predominantly alunite, kaolinite,silica (as quartz and chalcedony), pyrite and sericite. Alunitization is a subset of this advanced argillic alteration.Sulfur isotope analyses have been performed on monomineralic concentrates from Şaplıca alunites and associated sulfides. The alunites (+ 8,9 %o + 10,7 %o + 12,8 %o) are enriched 34s, relative to sulfides (-1,3 %o; -2,9 %c; -5,3%6) which are depleted in 34 S . Calculated isotopic fractionation factors (a * = 1,007 - 1,018) and isotopic differences(A34s = 6,93 - 17,83) of associated alunit - sulfide pairs indicate the hypogene origin of alunites. This result is supported by the textural and mineralogical features of Şaplıca alunite deposit. It is most likely that requisite amounts ofH2SO4 must have been generated by a magmatic hydrothermal environments.

Abstract: The tuffs of Neogene basin around the Gördes Region have high content of zeolite about 2/3 magnituteof their volume and contain less or not in some zones. Zeolite mineral type is clinoptilolite in the lower tuffs and heulandite is present in the upper tuffs. This difference is seen clearly on the whole rock chemistry of two tuff units. The geochemical relations between chemical elements and the quantity of zeolitization were examined and it is found thatall the major chemical elements are mobile. Some elements were been liberated from fresh glasses and used again for zeolitization or other alterations in the same system. Although, some of the major elements may have come from out ofthe system. Lossing of SiO2, Na ^ and K^O, and gaining of A12O3, MgO, CaO and HgO have been determined whenwe compared unaltereted rock with zeolite - rich rock. These changes show more increasing in both the loss and gain inthe heulandite alteration than in the clinoptilolite alteration. 

Abstract: Oil shales have been deposited from Precambrien to Tertiary in the geological history of the Earth, andthey are distributed in Europe, South America, Western United States, and in Turkey. Middle anatolia, Western Blacksea, Aegean and Marmara regions are important in respect to oil shales in Turkey. Volcanosedimentary lacustrine basins of Neogene age are the main geological environments in which oil shales were deposited in Turkey. Himmetoğluoil shale field have been selected as an example among the others. So, only this field have been investigated in detail.Himmetoğlu formation occurs in a graben, caused by reactivation of paleotectonic structures in the neotectonicregime. Lithostratigraphical features of this formation have been investigated in detail on core samples.Himmetoğlu formation has 4 different zones: Green clay and conglomerate, lignite bearing, banded bituminousmarl, laminated bituminous marl. Organic matters and pyroclastic sediments which were transported in different periodshave been deposited together in the basin. 

Abstract: In this study the stratigraphy of the northern portion of Akseki region (Middle Taurus, Antalya), and itsdepositional environments is described. The units in the study area is divided in two tectonics slices and named as Akseki and Akdağ - Yelekdağ tectonic units. The Akseki units are represented by neritic facies during Jurassic (Dogger) -Middle Eocene time, and pelagic to hemi - pelagic during Eocene (Lutetian) time. In contrast, Akdağ - Yelekdağ unitsare represented by neritic facies until late Cretaceous (Maestrichtian), and hemipelagic to pelagic until Eocene (Lutetian) time.

Abstract: The vein type Pb-Zn-Cu deposits in Kurşunlu area are hosted by the Upper Cretaceos volcanicand volcanosedimentary units with an average attitude of N50°W / 75 - 85°NE. They contain galena, sphalerite, chalcopyrite, pyrite, chalcosite and hematite as ore minerals and accompained quartz, calcite and localy barite as gangue minerals.Previous sulfur isotope and fluid inclusion studies showed that the sulfur in sulfide minerals is magmatic origineand might have been leached from the surrounding volcanic rocks and mineralising fluid has a character of low salinityand dominantly contains NaCl (±KC1, CaCl, MgCl) indicating that the water may be meteoric origine.Oxygen and hydrogen isotope studies (81 8O = in the range of -3.4 ile +0.6 %o, 8 D = in the range of - 31.4 ile70.4 %o) show that the water in mineralising fluid is the deepsirculated meteoric water in mineralising fluid is the deepsirculated meteoric water with some 18O enrichment as a result of isotopic exchange reaction with the surrounding volcanic rocks. Carbon isotopic composition of CO2 in inclusion fluid indicate that the mineralising fluid might have penetrated trough the marine or terrestrial carbonate unites. According to the results of all field and laboratory investigations helded on the mineralization; it may be said thatthe vein type Pb-Zn-Cu deposits in the area were formed by the deep - sirculated meteoric water leaching the sulfur andpossibly metal ions from the surrounding volcanic rocks and depositing along the fault zones. 

Abstract: The geological constraints presented in this paper show that the northern strand of Neotethys isnon-existent and the existing suture is actually of the Tethys (Paleotethys). Geologic and published paleomagneticevidence has been integrated to the conclusion that this ocean has persisted for the entire Palaezoic and Mesozoic andhas been consumed through periodically recessing northward subduction between the Triassic and Lutetian in westernand central Anatolia.Western Pontides has been rotated dextrally during the Permo - Triassie, contributing to upwarp of the Triassicarc, initiation of rifting of the western Black Sea and obduction of marginal ophiolites onto the active margin. Theenigma for the coeval Pontian and Gondwanian Karakaya formations is briefly discussed with emphasis on regressivenature of Triassic - Early Liassic sedimentation in Pontides versus the continuous fining - upward Mesozoic sequencesof the passive margin.The Jurassic (Late Triassic - Early Liassic) granitoids of the Pontides are suggested to correspond to thefractionated residue of the basic volcanism of the Triassic arc. These granites have intruded the Karakaya formation andhave been transgressed by a carbonate - flysch wedge of the southward onlapping back - arc basin, the Black Sea, inliaison with oceanward shift of the respective compressive and dilatational systems of the fore-arc and back-arc basinsdue to a presumable recess of subduction. The deposition in the extensional basins has started in troughs of earliercolapse and the intervening areas have been subject to progressive submergence between Portlandian - Berriasian andthe uppermost Cretaceous.There has been an incipient collision during the Cretaceous with intense shearing of the fore-arc and thepremontories of the passive margins of the intermediate and Arabian plates. A HP/LT deformation deletes all pre -Cretaceous deformations along the 50 km. wide Tethyan suture. The Cretaceous shear zones repeat with widening,towards the north, deformation being resticted to planes of movement when sufficiently away from the suture, enablingobservation of juxtaposed Cimmerian and Cretaceous deformations.Ophiolites have been obducted onto the passive margins of both Tethys and Neotethys during the early stages ofthe collisional period, uplifted by imbricate thrusting on the passive margin, finally gliding in foredeeps(exogeosynclines) that have been forming due to rotational processes.The Neotethys has sutured along immediate north of Bitlis/Puturge massives by Late Lutetian. However, thecompletion of colage has lasted until the Late Miocene in between these massives. The role of transform faults foracquisition of the fit of continental masses has been emphasised. Numerous left-lateral transforms are still active,aiming to push Western Anatolia southwards, onto the oceanic crust in the Eastern Mediterranean, the part of theNeotethys which has not completed its obliteration.

Abstract: In this study the stratigraphical aspects of the Gürün autochthone between Gürün and Sanz part havebeen investigated. In the area, between time interval of Paleozoic and Tertiary, the 14 different units have been differentiated. The lower part of the Gürün autochthone (relative autocthone) is represented by rock units of the Upper Devonian and Upper Permian. Gümüşali formation (Upper Devonian), is composed of sandstone, quartzite, limestone, dolomite and shale and Yığılıtepe formation (Upper Permian) consist of limestone and dolomite. The Carboniferous and LowerPermian is not represented by any units. The boundary relation between Yığılıtepe formation and, recrystallized limestone, clayey limestone, marl, sandstone of Katarası formation (Lower Triassic) is an unconformity. The presence ofMiddle Triassic has not been detected.The firstly differentiated units of the Upper Triassic and Lias, rock units; The Toycu Tepe formation (UpperTriassic) is composed of algae limestone and dolomitic limestone while the Çukuryurt formation (Lias) is representedby conglomerate/breccia, sandstone, algaecoral limestone, and shale. Yüceyurt formation of Middle JurassicCenomanian age is overlying the Çukuryurt formation with an angular unconformity. This unit consists of algae limes tone, dolomitic limestone and dolomite. The lower levels of Turonian-Coniacian and Santonian are not presend. TheUpper Santonian-Campanian (Yaniktepe formation) is represented by conglomerate/breccia, rudist limestone.The Akdere formation (Upper Campanian-Maastrictian) transitional to Yaniktepe formation is composed ofconglomerate/breccia, calcarenite and clayey limestone.In the study aera, The Adbalpman formation (Paleocene-Lower Eocene) locally trasitional with underlyingAkdere formation and is composed of dominant pebbly sandstone whose pebbles are conglomerate/breccia, calcarenite,clayey limestone, cherty nodule marl, Demiroluk formation (Lutetian) locally transitional with Abdalpmari formation isrepresented by conglomerate/breccia, Nummulite bearing limestone and marl. These rock units are overlain by an angular unconformity, which the youngest overlying units are conglomerates of Gövdelidağ formation (Upper EoceneLower Miocene) and sandstone, marl and limestone of the Gürün formation (Miocene).

Abstract: It this study, ostracode biostratigraphy with the lithologic features of the Lower Miocene - Pliocene squences in Antakya and surrounding area has been investigated. 142 samples were taken from 7 measured stratigraphicsections. 120 ostracode species have been identified from the Lower Miocene - Pliocene sequence. The datumplane ofCarinocythereis and Cyprideis with Neomonoceratina helvetica - Aurila soummamensis Zone, Gökçen (1984) havebeen described with these species in the region. This zone and datumplanes have been correlated within the previously -studied Tethys - Paratethys regions and with contemporary sequences deposited in Turkey. When the environmentaldistribution of ostracodes was taken in  consideration, together with shallow marina fauna, that lagoonal environmentostracodes are effective from place to place, found from the beginning of the sequence to top, were established.

Abstract: In the investigation area, the basement area formed by Pontid Lower Basic Volcanic Complex of Jurassic- Lower Cretaceous age and is intruded by the Harşit Granitoid. The unit is covered by the Lower Harşit VolcanicComplex of Upper Cretaceous. This rock group comprises three phases independent of one another, begining wiyh volcanism and ending with sedimentation. The youngest volcanics in the area are the olivine - augite basalts of Neogeneage.The rocks belonging to the Pontid Lower Basic Volcanic Complex are in a geochemical character, which is generally calcalkalen, but rather, showing transition to tholeiite and indicating a primitive arc environment. The Harşit Granitoid has I-type, peraluminus, calcalkalen features and characterize an island arc environment that is getting mature.The rocks bellonging to the Lower Harişt Volcanic Complex are also related to the subduction and are calcalkalen in character. 

Abstract: A number of chromite occurrences different in size and shape are encountered in Ortakale region. Chromites around Ortakale appear as massive and highly rounded bodies of 4 - 5 m in diameter. They are enveloped by a 2 -20 cm thick dunitic sheath, whereas those around Kurtdeliği Tepe are hosted by hartzburgites. The area of interest is amelange and hence, the chromites are more likely aligned along the fault zones.The massive chromites have higher Cr2O3 wt. % and lower Al and Fe*3 than the accessory chromites in juxtoposed gabbros. A gradual decrease in Cr/Al ratio occurs between the massive and accessory chromites. In addition, accessory chromites in harzburgites are mostly idiomorphic and are resorbed at varying degrees. These chemical and pysicalvariations in the chromites may be attributed to fractination which played an important role at the frist stage of chromiteprecipitation. Therefore, it may be concluded that the chromites are formed in an environment similar to stratiformcomplex, but have passed through a complex history before residring as podiform bodies in their present - day position.The chromites show pull - apart features and are altered along margins and fractures to ferritchromite that is enriched inCr and Fe and impoverished in Mg and Al compared with the parent grains. 

Abstract: Manganese nodules in the dölostone and radiolarian brown claystone in the Konak Formation of KoçaliComplex Upper Jurassic-Lower Cretaceous in age had been developed by early diagenetic processes. The replacement of silicic tests by Mn and other transition heavy metals such as Cu, Ni, Ba is the main mechanism of the nodule development. Both manganese nodules and associated manganese mineralization was effected by late diagenetic processes. The proceses resulted in the dissolution and migration of elements such as Cu, Ni, Mn, Si and addition of the elements such as Ca, Mg, Si. Thus, dolomite manganocalcite, calcite, quartz and pyrolusite veinlets formed as late diagenetic mineral assamblages. Hydrogenetic manganese nodules was not formed at the sediment sea water interface owing to oceanic bottom currents and episodic fluctuations of Mn in the sea water. Another reason for the absance of formationhydrogenous manganese nodules could be high sedimentation rate which indicates an enverionment close to active plate margin.

Abstract: In this paper, an environments and their interpretation of platform carbonates underlying the sedimentarytectonic sheets exposed on the Bozburun (Marmaris, Muğla) peninsula have been explained.Ptatform carbonates, at the base, begins with replacement dolomites being generally coarse crystaline. These passes upwards pelloidals. Packstönes and wacestones occured in the subtidal environments. Abudant bearing pelloidal carbonates have been most probably sedimented in the shelf lagoon. The sections of platform caibonates exposed on thesouth of study area are represented by loferitic siklothems upward deepening consisting of collapse breccia, algal crustand mats, abudant bioclast bearing limestones, from bottom to top, respectively. This facies suggesting periodic relativechanges of sea-level on the immediate backreef or bank-ende of the carbonate platform. 

Abstract: Zahuran and its vicinity are composed of two different units, (1) Middle Eosen Maden Complex which isthe oldest unit of the studied area, is composed of basalt, basaltic andesites, diabase, pillow lavas, sandstone - shale intercalations, red - gray mudstones, calcerous shale and various sized limestone blocks. (2) Lower Miosen Lice Formation is made up of alternating sandstone, shale and marls Lice Formation exposes through a tectonic window under theMaden Complex.The Mineralizations of Zahuran occur in two types; (a) Volcano - sedimantary mineralizations in pillow lavas,(b) Fault zone fillings what appears to be formed circulating hydrothermal solutions in the fault zone, These two typesof mineralizations show different charecteristies in respect two their relations with country rock, mineral assemblagesand wall-rocks alterations.The mineralizations in pillow lavas are roughly bedded and beds are parallel to pillow lava horizons, A wall -rock alteration which is closely related to the mineralization is absent, However a more conspicuos and general alteration is present. Ore minerals of this type are bornite, chalcopyrite and pyrite and in lesser amounts sphalerite, covellite -chalcocite,The fault fillings are concordant to the country rocks and have extensive alteration zones in wall - rock. Ore minerals of the fillings are pyrite, chalcopyrite, sphalerite and in supergene zones native copper and chalcocite - covelliteare present. The fault filling type mineralizations seem to be formed of the mobilized cations form the pillow lava mineralizations.

Abstract: Pre - Upper Maastrichtian is the first emplacement period of the ophiolitic melange which is the Neotethys product. During the interval of the Upper Cretaceous - Oligocene, ophiolitic malenge becamed thicker by thrusting due to the regional compressional tectonism and local emergence was an investigation area. Intermountain bassinsinfilled by continental elastics were developed in the early Oligocene, in front of the thrusts with approximately E-Wtrending and inclined to the North (Çayırlı - Tercan basin). Tectonic features of different character have developed during pre - and post - late Miocene, in the study area. E- W trending thrusts, high angle reverse - faults and asymetricoverturned folds with E-W trending axis have developed before Late Miocene. Following Late Miocene, compressionhas been compensated by lateral - movements which coused NW - SE, NE - SW striking right and left - lateral strikeslip faults and shear fractures with the same orientation. These structural data show that the investigation area and surroundings are under - control of appoximately N - S striking compressive stress. 

Abstract: The genus Cideina Sirel is characterized by the presence of the orbitoidal lateral chambers on the dorsalside of the shell. Despite of the absence of these lateral chambers, a foraminiferal beast was described and figured as Cideina by Meriç ve İnan. Regarding that the comparisons materials of the authors is very probably a quite differentgenus, the discussion seems to be principally inconclusive. Because of the presence of the orbitoidal lateral chambers onthe dorsal side, Sirtina Bronnimann and Wirz was placed in Lepidorbitoididae by Loeblich and Tappan. Consideringnumerous structural similarities between Sirtina and Cideina, Sirel followed Loeblich and Tappan and placed the Anatolian genus Cideina also in Lepidorbitoididae. In the orginal description, however, Sirel clearly remarked that a distinct family name should be used for such types. These facts also seem to be completely ignored by the authors. On theother hand the name of the type species of Cideina, the terms of the lectotype and paratypes have been used wrong byMeriç ve İnan.