Türkiye Jeoloji Bülteni

Abstract: Three different vein type fluorite mineralisations are observed in the Akçakent area, located within,the Central Anatolian Massif. These veins that are termed Kumlutepe (I), Değirmensırtı (II) ,and Yoncalıöz (III)occur in the Paleocene aged gabbros, alkali siyenites ,and porphyritic syenites. The gabbros ,and syenites are intersected by rhyolite dykes which contain fluorite ,and quartz. The veins I ,and II contain a poor paragenesis whichconsists of fine grey quartz, green fluorite, yellow fluorite ,and calcite. In the vein III, a different paragenesis is seen,in which, pale white fluorite, yellow fluorite ,and sulfide minerals are observed. The green fluorites of the veins I ,and II show similar fluid inclusions ,and homogenisation temperatures (14(M50oC). On the other hand, the vein IIIis poor in fluid inclusions. These inclusions show lower homogenisation temperatures (130°C) ,and higher salinityvalues.While the faults extending in NW-SE directions are the cause of the formation of the veins I ,and II, the veinIII has formed probably in the final stage along a NE-SW running fault at the syenite-gabro contact. Fluid, inclusions data show that the fluorites are of hydrothermal origin.The veins considered in this study show similar features to those of the other fluorite veins occurring in theCentral Anatolian Massifs.

Abstract: The aim of this study is to demonstrate the basic geological characteristics of the region where thePontides and the Taurides are the closest to one another, and to interpret the structural evolution.Four major units of pre-Eocene age have been recognized in the study area. They are tectonically related toone another and reflect different environments. These units from north to south, are the Kelkit Autochthon, theÇimen Dağı Nappe, The Erzincan Nappe and the Munzur Limestone.The base of the Kelkit Autochthon consists of the greenschists and an intrusive Gümüşhane Granite. TheLiassic detritics transgressively cover the basement rocks. The Liassic rocks grade in the Upper Jurassic-LowerCretaceous platform carbonates. This part of the autochthon represents a stable continental margin. The Jurassic -Lower Cretaceous rocks are overlain with an an angular unconformity by the Upper Cretaceous-Paleocene volcano -sedimentary rocks.The lowermost part of the Çimen Dağı Nappe consists of the Tokat Metamorphites and partly of the Carboniferous-Permian volcanosedimentary rocks. A heterogenous rock assemblage of Jurassic-Lower Cretaceous age coversthe basement rocks with an angular unconformity and represents continental shelf deposits. The Erzincan Napperepresents the Upper Cretaceous-Paleocene subduction complex and its products.

Abstract: One of the basic requirements of a healthy urbanization is compliance with the geological environment.During the urban planning stage this requirement is very often neglected and it still maintains itself as the mainissue of the agenda only when the problems arise. A typical example of this may be seen in the city of Samsun.Dense and widespread urbanization, which shows itself as a natural consequence of an increase in population, forcedthis coastal town to expand southward by climbing uphills. This southward climb, which was accomplished in spiteof adverse geological environmental conditions, has now started to reveal its consequences. Today, the majorityof the town is under the threat of landslides.Major factors which contribute to landsliding include the slope geometry, rock type, condition of rock, andgroundwater. Thus, detailed geological, morphological, hydrogeological, and geotechnical studies were conductedin the study area. In addition to these, the degree of damage on the existing structures has been determined in order to investigate the soil-structure interaction phenomena. Such investigations provided the basis for the microzonation of Samsun metropolitan area. 

Abstract: Beydağları and Antalya Miocene basins which are developed partly independent of each other, and Antalya Upper Miocene-Pliocene basin which is developed totally independent from the others make up the mainAntalya Neogene basin.The Beydağları Miocene basin of Western Taurus partially extends in the study area. The rock units of thebasin start with; the Aquitanian Karabayır Formation which csnsists mainly of limestons with Rhodophyta andcontinue with the Burdigalian and Langhian Karakuş Formation consisting of flysch type sediments and the overlying deltaic conglomerate. This formation, which fills the basin, has been developed during the Middle Miocenewhile the Lycian nappes were thrusting. ,The Antalya Miocene basin in the west of Middle Taurus lies between the Beydağları and Anamas-Aksekiplatforms. The basin consists of the Aksu Formation which includes terrigenous conglomerate-siltstone, marine :conglomerate-sandstone and reef limestone lenses; the Qymapmar Limestone of mainly reef limestone; the Çakal- ••lar Formation consisting of limestone breccia and packstone alternated with clayey limestone; the Geceleme Formation of limy claystone -sandstone alternation; and the Karpuzçay Formation which is composed of shale-sandstone-conglomerate alternation with occasional volcanic tuff interbeds. This sedimentation period started in Upper ~Oligocene and ceased in Upper Tortonian as the basin was compressed first towards the-west and later towardsthe south by the Aksu phase. In the area elevated by this compression, the Taşlık Formation consisting of clayey -:limestone -limestone-blocky conglomerate (some are gypsum) has been deposited locally in Lower Messinian.The Antalya Upper Miocene and Pliocene basin lies in the west of Middle Taurus. It appears in the south ofthe Aksu valley and along the Mediterranean coast as a post-tectonic unit. The Messinian Eskiköy Formation ofconglomerate-sandstone, the Gebiz Limestone sometimes reefal showing lateral gradation in the Eskiköy Formation, the Yenimahalle Formation of Lower and Upper Pliocene age including limy claystone -sandstone, and theUpper Pliocene Alakilise Formation which consists of sandstone with volcanic tuff and conglomerate make up therock succession of this basin.

Abstract: 22 represantative samples of volcanic rocks taken from 16 formations (Eocene-Recent) from Ayvalık,Edremit, Dikili, Bergama, Soma, Bigadiç, Kepsut, Sındırgı, Gördes, Demirci, Kula, Denizli and Söke districts ofWestern Anatolia were analysed for major, trace and rare earth elements for Sr isotopic ratios and radiometricallydated by (K/Ar) method. Rocks of rhyolitic to basaltic composition yielded calc alkaline affinities with the exception of some alkaline basaltic rocks through application to various diagrams.The samples are rich in Ba, La, Pb, Mo, As, Rb, Sn, Sr, Th and U; implying an intraplate origin and anatecticmelting of the continental crust. It seems that the youngest phase of Kula basalts are possibly the only rocksoriginated from the mantle according to evaluation of normalized trace and rare earth element contents. Othersamples suggest partial melting of the Continental crust with indications of contaminations supported by Sr isotopic ratios of 0,7030-0,7096. Alibey Volcanics (31,4±0,4 m.y) and the youngest phase of Kula basalts (25000 ±6000y) respectively correspond to the oldest and youngest Tertiary events.

Abstract: Two stratigraphically controlled ore zones, which do not have any relationship with each others interms of their genesis, mineralogical and chemical com position as well as their age, crop out to the south of Şarkikaraağaç (İsparta). The lower ore zone is followed on an unconformity surface between dolomites of ÇaltepeFormation of Lower-Middle Cambrian-age and Feletepe Formation of Dogger-age It consists of discontinuous occurrences of authochtonous «bauxitic iron ore» consisting of mainly hematite, chamosite, kaolinite, pyrochroite, diaspore and goethite. Their source rocks were probably reddish colored sandstones of Ordovician-age from northernpart of Sultandağ. On the other hand, the ferruginous bau xite-bearing upper zone, thicker and with more continuous distribution than the first one, is found between Upper Jurassic Kıyakdede formation and Upper Jurassic -Cretaceous Karayaka formation. Lateritic bauxites of the upper zone were originated from dolerites which showsome alternations with them. These autochtonous bauxites are composed of mainly boehmite, diaspore, kaolinite,hematite and goethite, with small ameunts of anatese, magnetite, ilmenite, pyrite, krandallite, calcite and chlorite.Occurrences of the ferruginous bauxites were formed under weak acidic conditions in a weathering environment containing great amounts of silica and relatively low amounts of aluminum with respect to mineable bauxites. This was the result of the insufficient development of drainage systems under lateritisation conditiens, different mobilities of elements and interruption of lateritic processes because of new layers of volcanic rocks covering the bauxite horizon. 

Abstract: In the present study, the determination and stratigraphic evaluation of the ostracode fauna of thesedimentary rocks of Montian-Cuisia n age exposing at south of:Polatlı, are carried out, and a systematicdescription of new species is given.At the bottom of the Lower Paleogene sequence in the region, takes place the «Mollaresul Formation» of UpperJurassic age. Abovethes unit, the Kartal(Montian), Kirkkavak (Thanetian-Ilerdian) and Eskipolatlı (Cuisian) formations come with a total measured thickness of 1230 m. The whole sequence is unconformably overlain by theAğasivri Formation of Neogene age.Five of the 44 ostracode species of this study, are found to be new, and described here in a systematic order,and a chronostratigraphic and ecostratigrapliic evaluation of the fauna is also given.

Abstract: The Karadere Metabasite of the Çangal Metaoplıiolite, located in the northeastern part of the Daday -Devrekani Massif, consists mainly of metagabbro, metadiabase, metaspilite, metaporphyrite etc. Additionally orthophyllonites occur within the shear zones. The mineralogy and petrography of these units are investigated in detailand wholerock analyses are done. The rocks are also analysed for their metallic element contents.In this study the metallogeny of the Karadere Metabasite of the Çangal Metaophiolite is investigated. Thegeochemical analyses are statistically evaluated and the results are discussed as indicators for potential mineraldeposits. The studies have shown and the Cu and Co contents could be indicators for economic deposits. Although the Zn,Ni and Cr values are high, further detailed studies are needed to determine whether they correspond to economic mineral deposits.