Türkiye Jeoloji Bülteni

Abstract: Menderes Group is characterized by two main lithologie units, one of which is basement rocks consisting of migmatite and augen gneisses, and the other is cover rocks composed of alternation of finegrained gneisswith tourmaline, micasehist with garnet, marble, quartzite, epidote - ehloritoid schist and calcschist. The evaluation ofthe different orientation (NE-SW in basement, NW-SE in cover) of the main tectonic elements, such as foliation, joints, veins, fold axes, linearity of various minerals and quartzo-feldspatic augens and boudinage developed in bothbasement and cover rocks, together with the other field and laboratory evidences indicates that the relationshipbetween the basement and the cover is an angular unconformity. In addition contrary to the former ideas, these different tectonic patterns in both basement and cover rocks indicate that the general structural shape of MenderesGroup is not a dome. The concentration of quartz veins, which are the post - anatexitic features in migmatization,in both basement and the lower part of cover rocks implies that the migmatization has mostly occurred during anearly Alpine orogenic phase, after the deposition of the cover rocks. 

Abstract: The Aladağ region mainly consists of the thrusted allochtonous sequences of Yahyalı, Siyah Aladağ,Çataloturan, Küçüksu, Minaretepeler, Üstkuşak and Beyaz Aladağ and includes ophiolitic melange, Tertiary sedimentsand moraines. The first eight sequences were deposited during the period from Devonian to Lower Cretaceous. Thesequences of Yahyalı, Siyah Aladağ, Küçüksu, Minaretepe and ophiolitic melange are mineralized. Besides the stockwork - type Aladağ - Delikkaya mine, all of the zinc - lead carbonates were deposited along tectonic fractures trendingN - S and NE - SW.The orebodies, which were formed through several stages, are probably hydrothermal in origin. Primary originand the formation of ore minerals represented by sulphide mineral parageneses can be explained by two models.According to the first one the ores were emplaced by either lateral segregation processes- hydrothermal solutionsin the above five sequences during Middle - Upper Creta ceous before the thrusting- According to the second modelthe ores are related to the Paleocene - Lower Eocene Yahyalı granitoids- The ophiolitic melange belts lying underthe thrusted sequences did not allow the migration the ore solutions upward in the upper thrusted sequences. Geological data have shown that the second model is more acceptable for the study area.Ore bodies in the Aladağ region were deposited simultaneously with those in the Bolkardağ region which arerelated to the Horoz granitoids- These two districts were separated by the Ecemiş sinistral fault in their presentposition.The sulphide ores are affected by multikarstification during Middle and Upper Tertiary through several phases of uplift and subsidence of the region.

Abstract: In the Avnik area of the Bitlis Massif, the oldest rocks of the Lower Unit are a series of basic to felsic calc - alkaline metavolcanic rocks (454 ± 13 Ma), inter bedded with magnetite - apatite ores. These rocks are intruded by the Avnik ,and Yayla granitoids (347 ± 52 Ma) ,and unconformably overlain by an Upper Unit of micaschists ,and Permian marbles. The entire sequence was most recently deformed ,and metamorphosed during the Alpine orogeny. The metavolcanics ,and granitoids are extensively feldspathizcd ,and silicified.Although many of the metavolcanics retain porphyritic, spherulitic / volcaniclastic textures, their K`Na ratioshave been severely altered, to produce albitites ,and K-feldspar rocks. The probable cause of the feldspathization,which also affects the Avnik granitoids ,and the micaschists, is reaction between the rocks and the sea water that pervaded the basement during deposition of the overlying marine sediments. This metasomatic event is dated by a Rb - Srwhole-rock age (91 ± 9 Ma) on the metavolcanics, suggesting that the reactions coincided with the expulsion on theheated fluid phase during the Eoalpine orogenic phase- The rock/water reactions have altered the Rb/Sr ,and K/Rbratios, ,and homogenized Sr isotopes, but REE patterns appear to be undisturbed.REE patterns, combined with major - element chemistry, suggest that there is no genetic relation between thegranitoids ,and the metavolcanics. Metavolcanics may have been derived either by extreme fractional crystallizationof more basic, more plagioclase - rich magmas, / from anatexis of a feldspathic rock where plagioclase was an important part of the anatectic residue. A crustal anatectic origin is suggested for the granitoids, which is consistent withthe available Sr isotope data.

Abstract: The metamorphic rocks of the Bitlis Massif consist of two groups which are called the lower andthe upper associations separated by an unconformity. The lower association with a possible age of Precambrian iscomposed of metavolcanics, gneisses and crosscutting granites; the upper association, which has a probable age range of Cretaceous, is composed of micaschist and marbles.The apatite - bearing iron deposits of the Bitlis Massif are in the lower ossociation and located along distinctstratigraphic horizons.In the Avnik (Bingöl) region apatite - bearing iron deposits are intercalated with metavolcanics and massive,banded and lensoidal in shape. These deposits are volcano sedimentary in origin. The ore bodies show variations alongtheir strikes and may pinch out in short distances due to irregularities in the volcanic topography where they deposited. Stratification and thin sedimentary laminae are hard-to recognize in the ore bodies. Magnetite is the dominantmineral in the deposits of this region. Contrary to the lateral irregularities of the deposits of the Avnik region, those of the Ünaldı (Bitlis) area can be followed for several kilometers along their strikes. The deposits of this second region have very regular and fine laminated distinct internal sedimentary structures. There are thinly laminated metachert intervals in the Ünaldı deposits- It is clearly demonstrated that the deposits of the Ünaldı region in which apatite is the dominant mineral, were formed by an undistirb ed sedimentation.The characteristics of the apatite - bearing iron deposits of the Avnik and Ünaldı regions, which are associatedwith metavolcanics and metaeherts, indicate that they are volcanosedimentary in origin. In the both regions the orebodies are cut and partially assimilated by younger palingenic granites. Both palingenesis and multiple metamorphism and deformation were effective in forming the complicate structures.

Abstract: In this study, to investigate the relationship between ore genesis and trace element contents of,pyrites of massive sulphide deposits from Turkey and Cyprus, 42 pyrite samples from 14 deposits are analyzed fortheir titanium, nickel, cobalt, vanadium, selenium, and arsenic contents which are characteristic for pyrites. Thesamples were taken from Pontid type and Cyprus type massive sulphide deposits. The samples used were from,for Pontid type deposits, Lahanos, îsrail, Kızılkaya, Kotarakdere, Madenköy-Çayeli, and Anayatak-JMfurgul; and forCyprus type deposits, Küre (Aşıköy and Bakibaba), Ergani I Anayatak and Weiss), Madenköy-Siirt, Agrokipia, Mavrovouni, and Skouriotissa.Titanium, cobalt, and arsenic contents, cobalt: nickel rations, and to some extent nickel contents appear aspossible discriminators for the two different types of mas sive sulphides. The ranges and means of titanium and cobalt are higher in Cyprus type massive sulphides compared to Pontid type. Arsenic has similar ranges in both types,but it has a higher mean in Pontid type deposits Cobalt: nickel ratios, both ranges and means, display an increasefrom Pontid type towards Cyprus type massive sulphides- The ranges and the means of nickel contents are slightlyhigher in Cyprus type compared to Pontid type. Neither the ranges nor the means of vanadium and selenium contents appear to be useful for distinguishing the two types of massive sulphides. 

Abstract: Volcanic rocks cropping out around Denizli in Western Anatolia have been petrochemieally analysedand they have been correlated with the similar volcanics surrounding the region. Their origin and plate tectonicimplication have also been discussed. Upper Pliocene volcanics are shoshonitic type. They consist of shcshonitic basalt, latite and trachyte. Their petrochemical characteristics indicate that they have been formed by continentalrifting due to tensional forces acting on this sector of the Western Anatolia. 

Abstract: New (bo) values were measured for 64 K - white mica specimens from the Menderes Massif (W. Turkey) by XRD. The mean value for (bo) parameters was found to be 9028 °A. The pressure of metamorphism of theMenderes Massif lies in the range between low and high pressures, that is intermediate. During the Alpine metamorphism, two metamorphic phases of different pressure developed in edge central regions of the Massif. The (bo) parameter of muscovite in the K. Menderes group is higher than of the other two groups (Ören and Milas) and Ören groupis smaller than that of the other two. It is determined that the (bo) values K. Menderes group mean value 9.036, Milas group mean value 9.035 and Ören group mean value 9013 (represent the results of the younger phase in theedge terrain of the Massif). The cummulative frequency curves of parameter (bo) of Menderes Massif is compared tomassives all over the world. 

Abstract: The investigated area is situated in the south and southeast of Şarkışla (Sivas), in which formationsof Upper Cretaceous - Paleocene, Eocene, Oligocene and Pliocene ages crop out. While Upper Cretaceous - Paleoceneis represented by turbiditic limestones intercalated with tuff, Tuffite, volcanic sandstone and lavas, Eocene is only represented by conglomerate and clayey limestones. Both of them are in marine origin. Oligocene is composed oflagunar gypsium and iacustrine sandstone, conglomerate, and marls. As for to Pliocene is also represented conglomerates, clayey limestones and basalts in terrestrial origin- Ophiolitic melange occurrences forming the basement (?)in the study area have been emplaced by gravity slides in the form of olistostromes in  the sediments as seperatedsheets from Paleocene up to the end of middle Eocene. Volcanoclastics, turbiditic limestones, the secondary emplacement of the ophiolitic melange in the form of olistostromes and the geochemical character of the volcanism indicate that the study area has been developed as a kind of rear - arc basin during Paleocene time.

Abstract: In this study the source rock possibilities of the Maestrichtian, Paleocene and Eocene sediments cropping out in the western margin of Çankırı basin have been investigatedThe percentage of the total organic carbon (TOC), kerogen types, the vitrinite reflectance values, and the paragenesis of the clay minerals as well as illite crystallinity values have been determined in the shale samples obtainedfrom four measured stratigraphie sections.The results of the analyses; carried out on the Maestrichtian and Lower Tertiary formations suggest that

-They do not contain significant amount of organic matter,

-The available organic matter is more suitable for the production of gas rather tham oil and they have notalso reached to complete maturity.

Similar analyses were also applied to the upper part of the Haymana formation (Maestrichtian) of the Haymana region- It is again concluded that the shales of the upper part of this formation are rather poor in organicmatter and they do not show good maturity. 

Abstract: Selected samples of the Recent sediments from the Black Sea basin were analysed for uranium employing neutron activation delayed neutron counting technique (NADNC) and fluorometric methods. The effects of thesolvent extraction and use of the different fusion mixtures were investigated with a view towards establishing themost acceptable fluorometric method of uranium analysis for these sediments. Experimental studies suggest that theanalytical results most close to those of the NADNC method were obtained by the steps, involving the digestion withan HF + HNO3 + HCIO4 acid mixture; followed by the solvent extraction procedure, using ethyl acetate in presenceof concentrated aluminum nitrate salting agent; and finally measurement of the fluorescence intensity of the pelletsprepared by the fusion of an aliquot of ethyl acetate phase and a fusion mixture. It was found that the uranium determinations without the solvent extraction step gave about 50% lower uranium values than those of the NADNC method- The use of either 2% LiF + 98% NaF + or 9% NaF + 45.5% N^COj + 45.5% as the fusion mixture had no effecton the fluorometric uranium determinationsSelected sediment samples from the abyssal plane and continental slope of the Black Sea were subjected tothe selective extraction procedures to assess the form of occurence and geochemical associations of uranium in thesesediments- The data indicate that about an average of 15% (range : 6.3% - 30%) occurs as easily exchangeable (groundwater extractable uranium); a major part of uranium (average : 51%, range : 21% - 89%) as sorbed + exchangeableions, mostly on organic matter (1 M Na acetate - acetic acid (pH = 5.5) extractable uranium); and about 24% (range :7%-36%) as bound in the organic matter with strong organo - uranium bonds (hydrogen peroxide extractable uranium proceeded by the acetate - acetic acid extraction). The remaining (about 25%) uranium is associated most probably with the detrital minerals. The organic matter-bound uranium constitutes the highest percentage of the total in the Sapropel Unit, whereas the detrital - associated uranium is relatively higher in the Lutite Unit and the Coccolith Unit samples of the continental slope, as compared to the rest of the samples.