Türkiye Jeoloji Bülteni

Abstract: Turkish borate deposits are products of lacustrine chemical precipitation which took place during theend of Tertiary in the Western Anatolia. In view of the existing mineral assembleges, it may be stated that thosedeposits were not subjected to any high temperature and pressure. It should be noted, however, that fallowing theburrial the primary minerals were replaced by more stable once. B2O3, Na 2O and CaO are by large the most importantcomponents in the developments of Turkish borate beds. SrO, MgO and As 2O8 are of secondary importance. 

Abstract: Kızılcahamam Beşkonak region is situated in Northern Anatolia which is attributed to the southernmargin of European Continent. Geological history between Cretaceous and Pliocene is an alternation of volcanic andtectonic events. This instability gave little chances to installation and establishment of lacustrine sedimentary basins.In a relatively disactive short duration of the magmatie activity of "Galatian Andesite Massive" a lacustrine regime,in which different and rich variety fauna and flora developed, were placed in Beşkonak volcanic deppresion.Sedimentary facieses in one hand and intraformational structures (underwater slumps, pseudonodules and clasticdykes) in other hand are expressions of sedimentation in versant basins. All these parameters define volcano-biosedimentary system as environmental type.Subject of research based initialy to paleoecologic and paleogeographic analysis enlarged by comprehension ofdinamics of volcanism, a phenomenon accompanied, and analysis of pyroclastic products. Utilisation of results presentscertain contributions in the fields of stratigraphy and paleogeography as well as paloecology. 

Abstract: Antalya Nappes are shown to be present in a narrow zone between Akseki and Alanya, in contradiction to autochthonous ideas which have been recently put forward again.

Abstract: Evidence that the extrusion history involves a younger and an older phase lies in the difference inbulk chemical composition of certain series of glassy rocks, such as perlite, rhyolite from the Cumaovasi domes.Frequency distributions constitute evidence for two groups of rocks on the Cumaovasi domes. The most obviousdifference is in the Rubidium content, one group containing 195--230 ppm Rb the other 300-350 ppm. All of the samplesthat possessed low Rb content were obtained from the Murtat, Mezarkaya, Karakaya, Yongah and Gülyaka, and allthe high Rb samples from the Çamköy, Dikmendağ, Karadağ- and Pilâvtepe.The cluster analysis demonstrate the presence of two entirely different groups of samples. For group I the meansfor A12O3, TiO,,,, MgO, CaO and K2O are higher than in group II, the means for MnO, Na_O and Rb are higherthan in group I.This difference strongly suggests that, if the Cumaovasi domes are the products of granitic magma chamber, thedifferences in composition of the rocks are the resault of magmatic differentiation.

Abstract: This paper concerne the systematic study of the Bchinoides collected within the project of the Miocenebiostratigraphy of the Ermenek (Konya). Aa a result it is distinguished the zonations of Echinolampas, Clypeaster,Schizaster species. 

Abstract: In this paper, relationships between metamorphism and chemical composition of garnets, taken fromregional metamorphic rocks surrounding Kırşehir Region are investigated.Investigation of metapelite and micaceous quartzite samples taken from three metamorphic zones in which metamorphic grade increases northward and northeastward, shows that MnO content of garnets decreases along thesame directions. MnO content of 29,23% of first metamorphic zone, turns out to be 12,81% in the second and finallybecomes 1% in the third zone.There is an apparent positive correlation between the modal content of garnets in metamorphic rocks and theMn-eontent of these minerals. It is found that garnets high in Mn-content appear to be less frequent and found inthe form of minute crystals whereas in the garnets low in Mn-content, the situation is reversed. Therefore it maybe argued that Mn-content of the original rock has been concentrated in occasional garnet crystals leading thismineral to be rich in Mn-content. However, chemical analyses of all garnet bearing rocks have shown that theyhave aproximately similar composition. Therefore this question arises: what were the conditions controllingnucleation and crystal growth of garnets starting from rocks with a similar Mn-content.As a result of this research it is found that estimation of physical conditions of metamorphism can not be donequantitatively by using composition of garnets nor through quantitative comparison of metamorphic conditions belonging to various metamorphic regions. However, existance of rather general relationship between increasing metamorphic grade and decreasing Mn-content of garnets from rocks of rather similar composition may be ruled out.

Abstract: The aim of this study has been to enlighten complicated structural relationshisps of the rock units, to,establish true sequence of the rocks, present and to evaluate the rezervoir area as a potential reservoir lake and also,discuss problems relating to water leakage, In the reservoir area mainly there are theree groups of rock namely a metamorphic the old basement in NE, overlying carbonates in the middle and, the ophiolites on top. They form a thick sequence of homocline dipping NW-This homocline which are made up of the rocks of different origine appears to have beenformed by emplacement of the ophiolite in the region. Base of the sequence, namely Paleozoic sir basement complex consist of phyllites and metaquartzite contacts between the main rock groups, e.g between the basement and the carbonates,and, the carbonates and the ophiolites are tectonically formed graduel transition. The present complicated distributionof these rocks and their relationships appear to have been controlled by tectonic rearrengments. It is the tectonic rearangements of the region causing the present distribution of the rock groups have also yielded, their lensings interculatings so on, Thus, formed an imbricated structure with clearely spaced thrust sheets. The younger strata of the Tertiary sedimentary rocks transgresivly overly these sequence. Second phase of tectonic transport from the N broughtthe region a sequence of flat-lyng carbonates over the continental Miocene detritials. The limestone of jurassic-çretaceous age known as the Andırın limestone which occurs in the topographycal highs and platforms as thin clips of thethrust. In the piedmont plain younger plato basalts and allivium cover large areas. In the reservoir area, the Ceyhanriver form a narrow and steep valley and is surrounded by high mountain range with the peaks reaching....m at Kayadüldül. The area in the north of the Bani axis is occupied by impermeable rocks of the sir basement complex, Therefore this part of the reservoir does not seem to bear any potential water escape problems. The axis of sır, DüzkesmetBani dams are also plonned on the basement rocks. Thus problems of water escape is not expected. Berke A and Bdams are on the Berke limestone which is sandwiched between the two impermeable units. It is concluded as a resultof detail investigation that no future water escape is forseen in these dams. However, water escaping problems ofeach axis cases should be considerd separetly from the reservoir problems. No surface expression of a deep karst whichmight have occured beneath the maximum water hight has been seen. 

Abstract: Description of Sivasella monolaterali» n. gen. n. sp. in Maestrichtian of Şarkışla (SW Sivas) region isgiven. 

Abstract: In the study area, ophiolitic melange and Neogene formations crop out. The ophiolitie melange is amixture of radiolarite, pelagic limestones, graywacke, olistostrome, cherty limestone, massive crystallized limestone,diabase, ignimbritic tuff, vitric tuff, gabbro, peridotite, quartzdiorite and porphyrite. The formation age of the ophiolitic melange, which is alloehthonous, is probably Maestrichtian, and its autochthonous basement cannot be seen inthe area which is studied. In contrast, along the Taurus belt, the ophiolitic melange is found thrust over theNummulitic flysch of Lutetian age and/or the Lower Miocene formations.The Neogene formations, which transgressively overly the ophiolitic melange, are characterized by laterally andvertically interdigitating units of marl, sandstone, reefal limestone, conglomerate and clayey limestone.

Abstract: Oil saturated channel-fills which range 1-5.90 m in thickness occur in turbidite bearing Haymana formation of the Haymana region. Although most channels are single cuts, some show several related phases of cutting andfilling. The walls generally have gentle slopes, but in one channel they slope 75°. The channel-fill sediments consistof thick sandstone beds ranging from very coarse to very fine in grain size. Petrologically these sandstones are camposed mainly of lithic fragments, plagioclase and quartz and can be confidently called lithic vake ( graywacke). Onthe basis of field evidences such as interbedding of channel-fill sediments with turbiditic sandstones and being enclosed by the pelagic marls it is thought that the most likely process for the cutting and filling of the channels wasturbidity currents. Presence of sedimentary structures both on the soles and in the channel-fills which are the resultsof turbidity currents strenghten this idea. In the light of these evidences it is interpreted that this channel-fill sediments were perhaps deposited on the lower parts of the submarine fans which gradually merge in the abyssalplain. The submarine channel-fan complex is a most important type of petroleum reservoir as demonstrated by recentexploratory work in California, Carpathians, Southwestern France and other areas. Therefore the presence of oil saturated deep channels in turbidite-bearing Haymana Formation has paleogeographie significance and they will alsoattract the attention of oil companies for finding commercial oil in unexposed parts of the Haymana-Polatlı basin. Agood understanding of the evolution of the Haymana-Polatlı region and the careful sedimentological studies of theturbidite formations are essential in finding the more proximal parts of the basin where the oil is likely to be accumulated.