Türkiye Jeoloji Bülteni

Abstract: The Ordovician around the Bosphorus which occupied a large area is composed mainly coarse clasticsediments named Arkose Series no fossil zones have beet found in these series. Near Çengelköy, in a chamositic bedintercolated with a laminated shales, the Middle Ordovician Conulariid Zone has been found (Arıç, 1955; Sayar (Arıç),1970); above these beds ConoeMtina sp. an upper Ordovician CMtinozoan has been identified (Taugourdeau-Abdtisselâmoğlu, 1962). The graywackes which succeeded comformably the laminated shales are probably of Ldandoverian age.About 40 km south-east of Çengelköy the graywackes overlie the Arkose Series and massive quartzite containLower Llandoverian (Rhuddanian) brachiopods in the Eopleetodotonta dupIicata-Cryptothyrella (Hindeîîa) Zonewhere they are associated with the other brachiopods and corals mainly Halysitids. The lower part of the graywackeshave some brachiopods (Skeuidioides aff. asteroidea) associated Diplograptidae (Climacograptus aff. normalis). TheBarchiopod-Graptolitid Zone and its assemblages which have been found the first time in the shelly facies of the LowerPaleozoic Series of Istanbul might be the Uppermost Ordovician-Barly Llandoverian (Kliuddaman At) in age, becausethe typical Ashgillian faunas are not known yet in the Bosphorus area.

Abstract: This study concernes the recent discovery of marin sediments of lower Triassic age in Hacılar region (NÇubuk-Ankara) emphasizing its stratigraphy and foraminiferal fauna content.The lower Triassic sequence of the Hacılar region, which is called metadetritic complex, is composed of sandstone,conglomerate, siltstone, diabase, spilite and recrystallized limestone. This complex contains also limestone blocks of Permian age and some thin layered, fossiliferons limestone of lower Triassic age. According to the characteristic foraminifera found in this layered limestone, the age of lower Triassic "Scythian" has been given.

Abstract: Menderes Massive covers an extensive area in soutwestern Anatolia forming a dome-like structure. It consists of a core characterized by augen-gneiss, granite-geneiss and migmatites and an envoloping very low-to low gradeschist sequence. The present study which hes been carried out in the northern part of the massif, near Simav, suggestspelitic sediments and shales for original rocks of the core metamorphised in almandme-amphibolite facies weth migmatization in deepar sections. The core is unconformably overlain by cover-schists at the base contain fragments ofkyanite, staurolite, turmaline and higher grade metamorphic rock. Basic and ultramafic rocks, which are closely relatedto the cover-schists of Paleozoic age reveal a similar kind of metamorphism and folding with these cover-schists. Themetamorpism of the green schists is of Hercynian age. Lower Mesozoic elastics containing schist pebbles, overlie thecover-schists with an angular uncorformity. 

Abstract: The petrological results of the the calcalkaline volcanics which have covered large areas in Uşak areafrom the Middle Miocene to Upper Pliocene were given. These results were compared with the other volcanics of theAegean region, and the origin of the volcanics were interpreted according to plate tectonics. The first volcanic accumulationstarted in the Middle Miocene as rhyolitic and rhyodacitic tuffs and lavas. During the Upper Miocene, rhyodacitic,trachyadesitic and aiidesitic lavas, tuffs and agglomerates generated. Andesitic products developed in the Lower-Middle Pliocene, The characteristic rocks of the last volcanic period are the Upper Pliocene aged basaltic-andesites.There are some quiet epochs between these four volcanic periods. All the calcalkaline Uşak volcanics probably generated from a paleo-subduction zone which had occurred when the African plate met the Aegean plate in the "LowerEocene. Some data of the todays subduction zone of the Aegean Sea at the south of Crete Island which accordingto some authors probably had started in the Middle Miocene and it gave its first calcalkaline volcanism products 2,7million years ago and its volcanic activity continued to recent time were presented in order to define this paleo-subduction zone. Furthermore, some brief information about all the volcanics of the Western Anatolia and the AegeanSea were given to compare them to the Uşak volcanics.

Abstract: The calcium silicates (spurrite, tilleyite), which generally develop under high temperature and low pressure conditions, are principally associated with intrusive bodies of basic composition.This study shows that the spurrite-merwinite facies (the observed mineral assemblages) in this area may occur at thetemperature and pressure conditions of the hornblende hornfels"  at the beginning of the "proxerie hornfels" facies.These calcium silicates may form at the granitic intrusion contact temperatures at about 600°-700°C.

Abstract: The lead and zinc occurrence of Karamağara kuyusu (Keskin-Ankara) is within the contact zone between the limestones and granitic rocks and also within the spilitic rocks. The mineralization is related to the hydrothermal solutions originating from a granitic magma.The ore samples have been studied under the ore microscope and the following minerals have been observed:Galena (two types), sphalerite, hematite, chalcocite, wittichenite, pyrite, chalcopyrite, bornite, and coveuite. Theinteresting textures and intergrowths observed among these minerals indicate that they are formed at high temperatures.

Abstract: Gediz and its surroundings have been affected by complex block faulting. In addition to E-W trendingfaults, which characterize the general tectonic pattern of the Western Anatolia, WNW-ESE and NB-SW trendinghave also developed.A distinct earthquake belt is present within the region and WNW-ESE trending Gediz and Simav faults, as wellas E-W trending Emet fault are believed to contribute much to the seismicity of the region. 

Abstract: The purpose of this investigation was to search the possibilities of reestablishment of the town of Gediz,which had experienced a destructive earthquake during March 28, 1970 at 23.02 hours, local time.Engineering geological map at the scale of 1:2000 was prepared to distinguish the zones showinglithological varia-tions. In addition to the geological studies, driling and geophysical investigations were alsoconducted. All together six different zones were distinguished. The areas underlain by colluvim, which isclassed as potential landslide area, should be avoided In the rest of the town, due regard must be paid to thefire danger, which may follow a future earthquake. 

Abstract: The most important bauxite deposits, that have actually been exploited in Turkey, are found in Western Taurus, inthe Akseki-Seydişehir region. These bauxites fill fossilized dolines and morpho-tectonic depressions (up to 40m, deep), but mayalso be found as stratiform deposits. The prebauxite karstification is very unevenly developed and no indication of continentalalteration is noticeable outside of these deposits. The mineralogy and geochemistry of the underlying, limestones and their comparison with the bauxitic materialshow, that they are totally independent. This fact confirms that the bauxites are alloehtonous; and emphasizes the impossibilityof the autochtonous "Terrarossa" theory. The discovery of small Gastropods within the bauxite and the presence of typical superimposed sedimentary sequences indicate that the bauxite was deposited in a shallow lagoon - lacustrine environ. The bauxi ticorelies directly over the limestones and gives no indication of insitu transformations of the clays to bauxite.On the other hand, several sedimentologieal and mineralogieal observations prove that the bauxite is of detrital originand was already transported as bauxitic material on a karstified pediplain. The aluminous material appears to havebeen transported as a fine mud in several steps during which the bauxitie evolution continued..The geochemieal study of these deposits indicates that the Akseki-Seydişehir bauxites have not been derived from ultra-basic -acitic rocks.In conclusion, the geological, mineralogieal and geochemieal study of the Cenomanian bauxites and the search of compatibleparent-rocks in the Western Taurus formations involve a genetic relationship with the Cambro-Ordovician basement((Seydişehir schists`),

Abstract: The Karaisalı limestone is a yellowish grey (10 YR 8/2), well indurated, tight and non to poorly beddedbioclastic limestone with well bedded horizons; there is frequent interfingering between the non-and poorly bedded stra-ta. Itis divided in six subfacies: 1) Coral-algal packstone and boundstone; 2) Small benthic foraminiferal-algal packs-tone; 3)Coral-algal wackestone and packstone; 3) Large benthic foraminiferal-algal packstone; 5) Globigerinid-algal packstoneand 6) Globigerinid argillaceous wackestone. All intertongue complexly with one another and are composed of variouscombinations of coralline algae, corals, foraminifera, echinoderms, moluscs, with minor amounts of Hatimeda, bryozoa,worm tubes, matrix and calcite cements. They accumulated on pre-Miocene topographical hiphs and within the adjacentareas as bank and associated deposits.

Abstract: Cosalite crystals are found in small cavities in skarn zones at Uludağ" scheelite deposit associated with pyrite and quartzcrystals. Needle-like prismatic cosaîite crystals usually form parallel aggregates. Unitcell dimensions, space-group, x-ray powderdiffraction pattern and chemical composition have been determined. Native silver is observed under ore microscope and alsorevealed by mieroprobe analysis.