Türkiye Jeoloji Bülteni

Abstract: Kan Yayla area contains rocks ranging in age from Jurassic to Tertiary. Upper Cretaceous aged ore-bearing dacite is the host tovarious mineral occurences, overlies Pontid Lower Basic Complex composed of spilitic basalt, andesite lavas and their pyroclasticvarieties of Jurassic. The ore-bearing dacite is overlain by the barren Dikkaya Dacite of Upper Cretaceous. All the lithologies areintruded by the Zigana Granitoid of Tertiary. The fracture systems caused by the Valles Type caldera formation in the area, is the main control for the mineralization. The Kan Yayla Zn-Pb deposit contains subparallelveins and has significant concentrations of gold.Fluid inclusion studies indicate low-temperature hyrothermal conditions for mineral deposition. Syngenetic paragenesis are given as:Sphalarite, galena, py rite, chalcopyrite,fahlore,fraybergite, native gold and electrum. Geochemical studies show that gold correlateswith antimony and arsenic, silver with lead, and cadmium with zinc.

Abstract: The Tumanpınarı mineralization is a volcanic rock-hosted, veinlike hydrothermal Fe-Mn deposit located in 35 km west of Dursunbey, Balıkesir. The geology of the study area consists mainly of andesite that form apart of the west Anatolian calc-alkalinevolcanism of Miocene age. Early hydrothermal activity was responsible for four types ofhypogen alteration in decreasing intensity:silisification, hematization, argilic alteration, and carbonitization. The ore stage clearly postdates hydrothermal alteration, as indicated by the occurrence of ore minerals in vuggy cavities and fractures in silica bodies. Major ore minerals are pyrolusite, psilomelane, hematite, and magnetite. Manganite, poliannite, braunite, bixbyite, limonite, and geothite in different amounts accompanyto these minerals. Mineralogical, it was recognized three ore types as dominant pyrolusite ore, pyrolusite+psilomelane ore, andpsilomelane+hematite+barite+limonite ore with pyrolusite. The average contents of the deposit are 27.98 wt % Fe2O3 and 22.40wt % MnO. High As, Ba, Pb, Zn contents of the ore seem to be an important geochemical characteristic of the Tumanpınarı deposit

Abstract: Clay minerals of Upper Cretaceous-Lower Tertiary sediments were determined and the factors governing their vertical and lateral distributions were discussed in the Orhaniye region, 25 km NW of Ankara. Examinations uncovered the close relationship between the clay stratigraphy and the depositional environments in the basin. Upper Cretaceous flysch sequence, which also constitutes the lowermost part of the studied section, consists of detrital Mite, smectite,chlorite, as well as corrensite occurred perhaps due to aggradation of smectites by means of Mg+2 rich solutions during dia genesis.Upper Cretaceous fan delta deposits and Paleocene proximal alluvial fan fades, appeared upwards, typically include a clay mineral association consisting of kaolinite and Mite. Chlorite of detrital origin may well be joint in the association due to distinct localsources. More upward, in the lacustrine fines and their lateral fluvial correlatives, dominant smectite, Mite as abundant as 50 % andsome zeolite minerals of trace amountwere detected. The uppermost part of the studied sediments, Eocene-aged shallow marine limestone-marl alternation includes mostly smectite and small amounts (5 %) of detrital Mite.

Abstract: The WNW-ESE-trending Eskişehir fault zone which separates the Aegean-western Anatolian block from the central Anatolian block is a right lateral strike-slip fault zone with a normal component. The fault zone is characterized by fault segments which trend between E-W and NW-SE around Eskişehir. Syndepositional and post depositional faults cutting Pleistocene and Holocene units indicate that the Eskişehir fault zone has been active since at least Pleistocene. At least 14 earthquakes (M 4)occurred on the Eskişehir fault zone in the 20th century and the 20th February 1956 Eskişehir earthquake (M=6.4) was the largest event in this century. The isoseismal map of the 1956 earthquake shows that this earthquake occurred on about 10-kmlong WNW-ESE-trending Oklubal-Turgutlar segment. There is no major earthquake record in the historical earthquake catalogues before the 20th century. However, both existence of mud dykes in Pleistocene units and deformation of Holocene deposits in front of fault scarps indicate that fault segments are active in this area and several M 6 earthquakes occurred in the last 10 000 years. Fault plane solution of the 1956 earthquake and field observations indicate that the Eskişehir fault zone which played an important role in the development of Eskişehir and İnönü plains is a transtensional fault zone.

Abstract: Göynük Pb-Zn mineralization is situated in the contact of Lower-Middle Triassic rocks and Upper Permian limestones of Siyah Aladağ Nappe around Aladağ region (Zamantı Pb-Zn province). Paragenesis of mostly carbonated mineralization consist of smithsonite, cerussite, anglesite, galena, pyrite, marcasite, sphalerite, geothite-lepidocrocite, covellite, calcite and quartzSome of very important data, which ore-host rock contacts does not show any differences of mineralogical composition, ore bodyrepresent syngenetic characteristics, magmatic events (or trace`s), an apt indicating origin of mineralization, are not seen close toarea, host rock of ore, limestone, have higher value ofPb, Zn, Cu, Ni and Co than the average composition of limestone, get from field and also laboratory study.From these data Göynük Pb-Zn mineralization appear as "Alpine type carbonate hosted Pb-Zn mineralization ". It is probablyformed by chemical precipitation (and later on carbonatized) from seawater saturated in metal ions between Upper Permian-Lower Middle Triassic.

Abstract: This study covers the systematic descriptions of two groups which have been found in the benthic foraminifera assemblage of the Paleocenel Eocene aged outcrops in the Western Pontids. The first group constitutes some stratigraphically significant species (Cuvillierina sireli İnan, Kathina selveri Smout, Alveolina (Glomalveolina) lepidula Schwager, Alveolina corbarica Hottinger, Alveolina minervensis Hottinger, Alveolina ilerdensis Hottinger, Assilina placentula (Deshayes), Nummulites burdigalensis de la Harpe, Assilina exponens (Sowerby), Discocyclina scalaris (Schlumberger) an the second group contains species (Alveolina cuspidata Drobne, Opertorbitolites transitorius Hottinger, Opertorbitolites latimarginalis Lehmann, Miscellanea minuta Rahaghi, Discocyclina fortisi fortisi (d` Archiac), Discocyclina archiaci (Schlumberger) bartholomei (Schlumberger), Orbitoclypeus ramaraoi (Samanta), Orbitoclypeus ramaraoi ramaraoi (Samanta), Orbitoclypeus ramaraoi (Samanta) crimensis Less, Nemkovella strophiolata strophiolata (Gümbel), Asterocyclina stella (Gümbel) taramellii (Munier & Chalmas) whose existence in Turkey has firstly been established.

Abstract: İn this study, the formations which crop out around Ilgaz-Çankırı and previously defined as Dumlupınar and Susuz formations,have been renamed as Sarialan formation based on the lithologic paleontologicalproperties and stratigraphicalpositions.Sarialan formation overlies in uncorformity with the Permo-Triassic aged Karakaya Unit that is base rocks. Sarialan formationhas been dividedand difined in  three members as Kimmerician-Lower Tithonian aged Dumlupınar, Upper Tithonian-Lower Valanginian aged Dodaş and Upper Valanginian-Hotrivian aged Beylerbeyi.The formation consits of sandy limestone, alternation of sandy limestone-limestone with marl interbeded, micritic limestone, lesssandy-clayey limestone and alternation of sandstone-silt stone-marl with pelagic limestone and volcanics materials.Sarialan formation formed in Tithonicfades and contains abundant Calpionellids and it comforms with overlying BarremianCampanian aged Çırdak formations.

Abstract: The main lithologies of Dodurga formation consist of clay stone, bituminous shale, dolomite and coals. Limestone and marls arerarely observed as intercalations. The dominant minerals are clays and uncommonly calcite and dolomite. Opal-CT is bounded upwith volcanogenic clay stones. The contents of quartz and feldspar are usually lower, altough they are determined in almost all levels.Pyrite and gypsum are commonly found in organic material-rich sediments. Analcime in one layer, jarosite in the uppermost coal zone and marcasite in the lower çoal zone are only encountered in the Kargı area. Huntite, siderite, barite and goetite appear in the Alpagut area. Magnesite are present in the Ayvaköy area. Dioctahedral smectite is a common clay mineral of all sub-basins. The amounts of illite, chlorite and kaolinite associated with this mineral partly increase at bottom of lower coal zone. Smectites have montmorillonite and beidellite compositions which are partly iron-rich and they could be distinguished from each other`s by means of hightemperature behaviours. Ideal calcite and Ca-dolomites are found as ideal rhombohedral crystals in the limestone and marls intercalated with clayey rocks, however high Mg calcites have non-ideal rhombohedral crystals in the coal zone. It seems that the variation in the species and habits of these minerals are controlled by the chemistry of micropores.

Abstract: It`s very difficult to estimate earhquake hazards. However, we estimate earthquake hazards by using computer technology especially Geographic Information System (GIS) and we evaluate hazard studies which has been carried out by researchers on 22 July 1967 at Mudurnu valley earthquake. In this study, we use database about geological information. We assumed some parameters according to geological database and we put Risk value to database. After that, we determined potential risk area that has occurred hazards by using overlay analysis. Finally the result of this study correlate with the result of earlier hazard investigation.From this correlation, we obtained % 65 precise result by using GIS. To obtain more precise result, we should have considered increasing database quality.

Abstract: Optimized land-use plays an important role in the performance of planing which are urban planing, industrial district, and likelarge engineering projects. Reliability of land-use planning is a function of an elaborated site selection study, which depends on thatof geological to geotechnical model studies. In this connection, identification of geomorphology, geology, physiography & climate,hydrogeology, engineering geology, seismicity and geotechnical characteristics of a delineated area forms an essential work. Decision-maker can only assesses the project in terms of timing, cost and environmental issues when convent data are available in land.Harbor, airport, organized industrial district and free zone projects are being conducted in Lower portion of the Filyos Valley. Coordination of such large-scale engineering projects taking the aforementioned criteria in account has significant role to optimizethe land-use.

Abstract: In this study, a microspheric individual of Orbitoides apiculatus Schlumberger having a large number of megalospheric embryos near the both peripheries of the test fossilised in the period of schizogony from the Asmaboğazı Formation outcropping around the north of the Asmayaylası Village (Southeast of Şereflikoçhisar-Central Anatolia) is described. The individual including 22 megalospheric embryos in different positions also brings out existence of schizogonic type reproduction in rich orbitoidal foraminifera community indicating shallow water paleoenvironments as seen in the examples o/Orbitoidcs species in various regions of Turkey.

Abstract: This study introduces a new type of manganese occurrence in Turkey. The occurrence is located near Zilan (Erciş, Van), associated with pumice tuffs cropping out in the region, and fills the spaces between thegalssy clasts in pumice tuff. It has a mono-mineralic composition containing 65-73 % MnO, 3-5.5 % K2O, 2.5-4 % BaO, 0.5-1 % SrO, 0.5-1 % CaO and 0.3-0.7 % Na2O. Accordingto such a chemical composition the mineral has been calculated to have a formulae of(Na, K, Ca, Ba, Sr, Mn+^)2 MngOjgxH2O.Such a composition is similar to but contains more Mn than romanecite. Zilan Mn occurence has a hydrogenetic-detrital origin based on the Al-Si diagram. Mg-Na plot indicates afresh water environment for its origin. These in turn suggets that manganese was dissolved by surficial waters from the basic to intermediate volcanicsin the region, transported as Mri*`"" or in the from of organo-metallic complexes, deposited within the pumice tuffs which provided alkaline-oxidising conditions.

Abstract: İzmit Bay, which is the eastern continuation of The Sea of Marmara, ending in three successively smaller bays, is about 50 kmlong and 1.5 to 10 km wide. It is a part of an east-west trending graben, which has been shaped by the NAF-Zone system. The Bayfloor is a shallow-shelf area.This study is based on the re-evaluation of the results from 13 seismic profiles. The recent sediments at The Bay floor display apre-Pliocene/Pliocene, Middle & Late Pleistocene andHolocene succession from bottom to top, and since, it can be defined as a PlioQuaternary Unit. Thickness ranges from 10 to 50+ msecs. Sediments are mainly composed of terrigenous elastics, varying from clayto pebble-gravel in grain size, and at a lesser amount, carbonates. Young cover is thicker at the south and east than other parts, because of deltaic pro gradation.The alluvial fan in the south, that has been forming Dil Burnu area, was deposited as Yalakdere Deltaic Sequence. Young sediments deepen eastward, due to a NNW-SSE trending vertical movement at the east of Dil Burnu. This structural line has been producing a submarine fan, off Dil İskelesi to the north. As a result of this lineation, it can be concluded that, there is a local tilting in thefan area.Since the faults at depths of The Bay bifurcates toward the surface, the development of flower structures must be emphasized.The Bay, itself, is probably a locked-up basin. As being examplified by the area between The Bay and Lake Sapanca, the easternmost (innermost) basin will may be a lake grodually passing (in)to a marshy area, through the filling-up by sediments.

Abstract: Maastrichtian is presented with rudistic limestone which contains benthic foraminifera of Rhapydionina liburnica (Stache), Fleuryana adriatica De Castro, Cuneolina cylindrica Henson and Cuneolina ketini İnan, and shows limited lagoon environment in theAdriatic Platform of Alpına Belt. On the other side, Maastrichtian excluding pelagic environment, is presented with rudistic limestone that contains benthic foraminifera of Orbitoides medius d`Archiac, Orbitoides apiculatus Schlumberger, Omphalocyclus macroporus Lamarck, Pseudomphalocyclus blumenthali Meriç, Lepidorbitoides minor (Schlumberger), Hellenocyclina beotica Reichel, Cideina soezerii (Sirel), Siderolites calcitrapoides Lamarck, Loftusia anatolica Meriç, Loftusia minor Cox, Loftusia harrisoni Cox andindicates a reefal environment. The outcrops of Taurid Platform which are similar to Maastrichtian aged benthic fauna of Adriatic Platform are present in Akdağ (Antalya), Hadim, Seydişehir (Konya), Saimbeyli, Kozan and Pozantı (Adana) regions.KIT transition in the Adriatic Platform is generally indicated with a breccia level which is present in the some part of the Taurids.  However, transition in Taurid Platform is generally represented by dolomitle limestone levels. In both cases, it indicates a short-period term for emerge. After, KIT transition, it is noteworthy that the benthic fauna got poorer in quantity and type in both platform.Danian is represented by limestone that contain miliolid and Protelphidium sp., Pseudonummoluculina sp., Hellenalveolina sp.in Adriatic Platform. In Taurid Platform however, these forms are replaced by Anomalina sp., Mississippina sp., Eponides sp. and primitive rotaloidal forms. Danian is represented by small benthic in which miliolid dominates in both platform. This fauna points tobays and lagoons in litoral lagoonal environments in which low energy conditions dominated.

Abstract: Sulakyurt granitoid is exposed at the north, western edge of the Central Anatolia. Gabbroic bodies ranging upto 1-2 km2 are outcropped within the Sulakyurt granitoid. This study is aimed toput out the deep structure of the gabbroic rocks within the granitoid atthe depth by 22 boreholes within the area. The granitoids have sinosoidal contact with the gabbroic rocks. The gabbroic rocks aredioritic in composition at the contact with the granitoid. The boreholes data reveal that the gabbroic rocks are extended towards thedepth within the Sulakyurt granitoids. As a conclusion these gabbroic rocks are nonophiolitic which they intruded in the granitoidmagma chamber as a mafic products and they crystallized as a syn-plutonic body.

Abstract: Türkiye Jeoloji Bülteni Ağustos 1997 tarih ve sayı2`de M. Tahir Nalbantçılar tarafından hazırlanan "Çay(Afyon) güneybatısında Sultandağlar Masifi`nin mesoskopik tektonik özellikleri ve jeoloji evrimi" başlıklı makaleyi okudum. Araştırıcının çalıştığı konu farklı olmakla birlikte aynı bölgede ben de genel jeoloji amaçlıbir çalışma yapmıştım (1987). Araştırıcının çalışması ileilgili olarak bu makalede gördüğüm bazı biçimsel ve bilimsel eksiklikleri aşağıya not ettim.

Abstract: Türkiye Jeoloji Bülteni`nin 1997 yılı 40/2 sayısında yayınlanan "Çay (Afyon) güney batısında Sultandağları Masifi`nin mesoskopik tektonik özellikleri ve jeoloji evrimi" isimli makaleme ilişkili Sayın î. Erdal Kerey`e ait tartışmaya, yanıtım aşağıda verilmiştir.