Türkiye Jeoloji Bülteni

Abstract: The Ramseyburg middle graywacke member of the Middle to Upper Ordovician Martinsburg Formation of Pennsylvania and New Jersey was analyzed petrologically in order to identify its provenances, with a view toward reconstructing the basinal and source-area evolution in a plate tectonic context. A total of 48 samples were studied, taken from seven localities along the Martinsburg outcrop belt,which extends for 220 km. These samples were analyzed for the following detrital grains: monocrystallinequartz, polycrystalline quartz, volcanic and sedimentary lithic fragments, plagioclase, and potassiumfeldspar. On each thin section, 500 points have been counted for these grains and been placed in triangular modal diagrams. Analytic data obtained from 200 basins which are formed by different tectonicregimes are represented by various parts of triangles. Therefore the relationship betwen tectonics andsandstone petrology are set up directly.Analyzed data reveal that the Martinsburg turbidites had two provenances: a more dominant recycled orogenic and a subordinate cratonic interior. The southwestern portion of the basin was dominantly fed by reworked Late Cambrian/Early Ordovician sedimentary cover, and the northeastern partof the basin received its elastics from granitic and gneissic plutons of the North American basementthat were exposed after the sedimentary cover was eroded. The rarity of predominantly basaltic detritusin the Martinsburg graywackes indicates that the arc provenance was not the prime source for thesesediments.The evolution of the Martinsburg basin and its source areas is accounted for by a plate tectonicmodel which requires the collision of the North American craton with an island arc or microcontinent left from Precambrian rifting. This proposed tectonic model provides additional insights regarding the emplacement of the Hamburg klippe, and of pillow basalts and thin volcanic ash layers presentelsewhere along the outcrop belt at the base of the Martinsburg Formation.

Abstract: In this study, economically important the lower and the upper lignite seams of the Somaarea have been examined palynologically. Palynologic determination of 16 different genera and 42species of sporomorphes indicates that the lignite series contain a microflora of Middle Miocene (EarlySerravalian) age.Qualitative and quantitative analyses of this microflora closely match with the EskiMsar pollenassemblages which give an age of Late Burdigalian — Early Serravalian.The spores and pollens of the region define a flora assemblage that indicates a dominance of theMediterranean or slightly more humid and hot climate during the deposition of the coal -bearing formations. 

Abstract: The Zn-Pb occurrences of the Aladağ Mountains are in the southeastern part of the Zamanti District of the Middle Taurus, Turkey. The mineralization depends neither on the stratigraphyof the host rocks nor on any magmatic activity. The occurrences are hosted by paleokarst features, developed at the post Cretaceous emergence surfaces in Permian ,and Jurassic limestone series. The distribution ,and shape of the ore deposits arc influenced by the local fracturing ,and paleokarstification related to the varying lithology.The orebodies were deposited as fillings of karstic networks ,and open-spaces in fracture zones. The mineralized material consists in general of chemically / mechanically transported fragments. Replacementof the wall rock represents an important process of mineralization only in structure-controlled weaknesszones in massive Limestones. The sulfide paragenesis consisting almost entirely of sphalerite, galenite ,and pyrite/marcasite, is rare in all occurrences due to oxidation processes. The oxidic ores contain predominantly smithsonite, hemimorphite, hydrozincite, Zn-Al-silicates ,and high amounts of limonite. The filling-type ores occurring in layers ,and/or as cement of clastic sediments reveal very heterogenous compodition ,and structures (mainly geopetal arrangement) with characteristic variations in different karst zones.The detritus between clay ,and pebble size are derived from -stratigraphically ,or tectonically- overlyingophiolitic ,and older sedimentary source rocks. The insoluble residues of the karstified limestones areonly of little importance.The main period of the karst filling ,and karst mine ralization is very probably of Eocene age. Resultson the ore deposition, from regional down to micros copic scale, considering also our geochemical datapoint to an epigenetic origin for the mineralization through remobilisation by exogene processes.

Abstract: Uranium occurrences in the Yeşilyurt area of Western Turkey occur in fluviatile sedimentary rocks which are underlain by low-to medium-grade metamorphic rocks of the Menderes massif.These occurrences are found in Neogene conglomerate and sandstone beds that contain a matrix ofabundant clay and silt. Uranium is present as a matrix impregnation in tabular lenses within the sandstone and conglomerate beds. Both oxidized and unoxidized occurrences occur. Both types are disseminated uniformly throughout the fine grained clay and silt matrix rich in carbonaceous matter. Unoxidizeduranium occurrences show no direct correlation with pyrite and siderite abundance.Ore grade uranium (0.05 % U3O8) concentrations in the oxidized occurrences are confined to sandstoneand conglomerate beds with clay and hematite matrix containing little or no calcite whereas very lowgrade (< 0.01 % U3O8) uranium concentrations occur in calcite-rich matrix of sandstone and conglomeratebeds. Authigenic pyrite and siderite formed during diagenesis. Uranium in solution was first adsorbedby clays and carbonaceous matrix and further reduced by mobile H2S.A large amount of uranium, concentrated to ore grades in the reduced sandstones and conglomerates, was dissolved by carbonate-rich solutions ascending along the graben margin growth fault and redistributed throughout the fluviatile sediments. A few occurrences of uranium survived the severealteration represented mainly by calcite and hematite. All the occurrences are epigenetic in originformed by groundwater solution that moved through the host rock. The massive gneisses are believed tohave been the only source of uranium.

Abstract: In this paper a finite element model is presented for the unconfined aquifer of the Erzinplain. In the model governing groundwater flow aquations are modified by introducing Dupuit assumptions for the non-steady state unconfined aquifer condition.Application of the model to the Erzin plain groundwater basin is accomplished by calibrationof the model for the irrigation season of 1978 and verification for the period 1978-1982. Sensitivityanalyses are conducted for aquifer parameters, mesh size, boundary conditions and recharge - dischargerates.Simulation of the response of the aquifer to chan ging hydrological conditions is accomplished bymeans of five control wells for which long term head distribution data are available. The resultsobtained have shown a very good correlation between the measured and the computed heads. 

Abstract: In this paper application of a finite element model to the unconfined aquifer of the Erzin plain is discussed and the algoritm of the com puter program known as GRWM is described. Thesensitivity analyses include the mesh size, hydraulic conductivity, storage coefficient, boundary conditions, and recharge-discharge rates. Model calibration is achieved for the irrigation season of 1978. Verification of the model is accomplished for the period 1978 thru 1982. The proposed model simulates the behaviour of the aquifer successfully. 

Abstract: Through the application of some statistical analyses to the abundant Icriodus specimens,Lower Devonian conodonts, collected from the Monitor and Toquima ranges, Central Nevada, U.S.A.,the evolutionary change in this fossil group is investigated. Under the light of ontogenetic concepts andobservations, the statistical frequency distributions of «elongation index» in the populations, which ismodified from width-length ratio as I-W/L, are evaluated mathematically. By the interpretations concerning evolution and taxonomy, the two species. I. steinachensis and I. claudiae are redescribed andthe hypodigms of the two are given. Mathematical methods, graphs, and interpretations are explainedin detail. 

Abstract: The outcrops of the Kuzgun formation which is of Tortonian age according to the previousstudies have a northeast to southwest elongation in the investigated area. The Kuzgun formation mainlyconsists of alternating conglomerate, sandstone, mudstone and shallow marine Ostrea horizons. Thethickness of this unit increases from west to east and maximum measured thickness amounts to 450meters. Serial sections for determining the facies distribution of the Kuzgun formation which comprises generally terrestrial and shallow marine elastics were measured from east to west. According tothe measurements the following main facies were determined: The Güvenç formation is overlain byshallow marine elastics which contain Ostrea and low sinuosity meandering river-meandering river deposits in the east (Kebenk sırtı) in order. Meandering river deposits are dominant along the Seyhan rivernear Catalan dam and southerly Deve Tepe area. The Güvenç formation is overlain by meanderingriver deposits and shallow marine elastics around the Kuzgun village in the west. Further west nearKızılyar Tepe the Güvenç formation is overlain by in the order; 1. shallow marine elastics, 1. meanderingriver deposits, 2. shallow marine elastics, 2. meandering river deposits, 3. shallow marine elastics. Atthe northern part of Tarsus and west of E 5 highway (Eskiköy Tepe) the Paleozoic basement is overlainby a thin conglomerate without Serravallian and pre-Serravallian deposits and it continous to the top byshallow marine alternating elastics and detrital carbonates. The Kuzgun formation is overlain conformably by the Salbaş tuff member which is continuous in a regional scale.The Kuzgun formation mainly consists of alluvial and braided river deposits of cyclic-alternating nature and shallow marine deposits. In the terrestrial deposits, conglomerate and pebbly sandstone arefound at the base of each cycle as channel fill deposits. The levee deposits forming from alternatingsandstone and mudstone are located near the main channels. The sub facies of flood plains comprisesfine grained, fairly laminated mudstones which contain abundant calcrite noduls. The shallow marinefacies of the Kuzgun formation mainly consists of sandstone, siltstone, mudstone and several Ostrealevels. The lower boundaries of sets are usually sharp and the upper level of sets have wave ripples,burrows and are bioturbated. The siltstone and mud stone of this succession contain abundant bivalves,gastropods and plant fragments and Ostrea layers.

Abstract: Early Eocene and Middle-Late Eocene flysch like fine grained sedimentary rocks in Gelibolu Peninsula were studied for their source rock possibility. Both facies consist of sand, mud, clayand normal flysch within different horizons. Fine grained rocks (claystone and mudstone) comprize% 80 of the total thickness of the sedimentary rocks. Organic geohemical parameters and clay mineralsparagenesis of the claystone and mudstone obtained from the measured stratigraphic section were investigated. According to the total organic carbon (TOC) and extractable organic material (EOM) dataSaz member may probably be considered as a source rocks however Karaağaç member may not bethe source rock. According to the vitrinite reflectance (Rm) data Saz Member rang young state andKaraağaç Member rang mature state. Oil and gas with low to awerage quality may be produced fromthem. According to the illite kristalinite index data Saz Member rank anchimetamorphism and metamorphism and Karaağaç Member is in the diagenetic stage.The clay minerals in the Saz and Karaağaç Members and their polimorphes indicated that those sediments may have been subjected to diagenesis at deepths between 30004700 meters.

Abstract: The Pb+Zn mine, in Afşin-Hüyüklü is already under the production. In order to direct thefuture explotation, geoelectrical surveys were conducted to determine extensional existance, dimensionand possible reserve of the are deposit. To accomplish that d.c. geoelectrical and natural polarizationmeasurements were taken over an andesite covered 45 000 m2 large area and along the profiles each ofwhich has 300 meter length and with sampling interval of 5 meters. Three conductive depositional basinswere located to be extending in E-W direction. Medium basin is already proven and is underproduction.This basin is recognized with lower average resistivity of 200 Ohm-meters, and it is surrounded withrelatively resistive flanks that of which is 450 Ohm - meters. The estimated widh of the basin is 120 to150 meters. There are two, four-and one conductive minearl zones in these basins from north to south,respectively. There zones extends in N60°E direction, and inclines to the north with an angle between 45 to60° and have various withd of 10 to 40 meters and resis tivities in the range of 100-150 Ohm - meters. The oreveins, underproduction take place in one of these zones. From the interpretation of the natural polarization profiles, it is determined that average depth of the mineralization starts from 10-15 meters andextends up to 100 meters below the surface. By using the interpretation results new locations for production galleries were recommended and possible expected reserve was estimated which is about 320 000tons, in the medium basin. 

Abstract: Petrclogical analyses of the Erdembaba volcanics in tha Central Pontides region are investigated and the mode of formation and genesis are interpreted. Pliocene volcanism is hyalodacitic showing characters of intermediate acidic rocks of the calcalkaline series. Petrochemical characteristics ofthe Erdembaba volcanics point out that they might have been originated from continental crust as aresult of anatexis.

Abstract: Palingenetic granites constitute the basement rocks of Mihhdere valley located to thewest of Kazdağ Massif, Turkey. The rock sequence consists, from base upwards, of foliated granite, migmatite, gneiss and marbles which are unconformably overlain by various schists and marbles. Different lithofacies of this sequence are overlain by a tectonic slice of melange and flysch. All these rocksare intruded by the Altınoluk Granite of Paleocene age generally forming skarn zones. Sedimentaryand volcanic rocks of Miocene age unconformably cover the older units.Paleozoic or pre-Paleozoic events probably played an important role on the structural evolutionof the massif. Upper Triassic was a period of overt hrusting and strike-slip faulting with associatednormal faults.Mineral parageneses point to a regional meta morphism of Barrowian type. Reported Abukumatype metamorphism is attributed to contact metamorphism. The metamorphic rocks display effects of aregional metamorphism of low, middle and high grades. 

Abstract: Volcanic rocks of the Pontides are widespread in the Sinop area. The rocks are mainlymade up of volcanic conglomerates, flow-breccias, pillowlavas, dikes and also associated with them arelava flows and rarely tuffs.Volcanic rocks have basaltic and andesltic compo sition and consist mainly of augite, enstatite, olivine,biotite, plagioclase and analcime. Chlorite, zeolite, prehnite, calcite and opaque minerals are found assecondary minerals.Rocks showing generally calc-alkaline characteristics are divided in basalt, andesite, latite-basaltand latite-andesite. The general distribution of their trace element contents (Cr, Ti, Zr, Sr, Y) and highV/Ni, low Ti/V values exhibit the characteristics of volcanic arcs rocks.It is concluded that the Sinop volcanics and the other volcanics of Upper Cretaceous-Eocene age inthe Pontids were generated by the subduction of the descending Anatolian-Tethys (Neo-Tethys) plate beneath the Pontids during the Upper Cretaceous-Eocene time.

Abstract: The Altmekin group, which formed the basement of the investigated area, consists of Gözet,Karasivri, Nuras and Bademli formations which are conformable to each other. The dominant lithologiesof Gözet formation are calcschists and greenschists. Karasivri formation is mainly formed of quarzitesand it shows transitions to marbles of Nuras formation. Upper Permian-aged dolomitic limestones ofBademli formation form the upper levels of the Altmekin group. The Koçyaka ophiolitic melange wasemplaced before Upper Campanian and it has tectonic relations with the Altmekin group. Upper Campanian-Lower Maastrichtian aged Maydos formation unconformably overlies the ophiolitic melange. Upper Miocene aged Hoydos formation and Plio-Qua ternary aged alluvioums cover the above mentionedformations.In the region, tectonic activities affected the formations in varying intensities due to their differentlithologic features and formed different types of folds. Approximately E-W striking, faults, overthrusts, fold axes and joints in different directions have been formed by N - S striking structural forces. TheAltmekin group has been thrusted over the ophiolitic melange, after the melange had been emplaced inthe region.