Türkiye Jeoloji Bülteni

Abstract: In the studied area formations of different structural setting are present. They have been classified and called, inascending order; Davras limestone, Çandır formation, Ophiolitie unit, Sütçüler formation And Aksu Çay formation.Davras limestone is apparently para-autochthonous. Çandır and Sütçüler formations have been correlated with theunits of the Western Taurids, in respect to facies and structure and suggested to be allochthonus,All of the Mesozoic units have been covered by EarlyMiocene Güneyce and Late Miocene Aksu Çay formations.

Abstract: Three different periods were effective in theEvolution of Aladağ Mountains. The first one is the stable continental marginperiod which occured from Upper to Lower Cretaceous. The second period includes the distraction of continental margin and the firstemplacement of ophiolites. During this phase continental margin was subsided due to block faulting and Senonian basin was developedon the platform type of carbonates of the shelf environment. The first emplacement of ophiolitic meterial was deosited in this basin toform an ophiolitie melange. The third period includes the deformation of continental margin and emplacement of peridotite nappe inMaastrichtian. Daring this time, Senonian basin was squeezed up by compressional stress and together with the basement it gainet acomplicated structure with several nappes. On top of these, Aladağ peridotit nappe and the metamorphic sheet, which occurs on thebottom of the Aladağ peridotite, were emplacement.

Abstract: The ophiolitic rocks, which were emplaced on the continental margin in the Aladağ region of Tauridsduring Maestrichtian, make up a sequence consisting of three units that are the ophiolitic melange at the base, themetamorphic slice over it, and the peridotite nappe at the top. One of the important subunits within the sequence isthe diabase dykes which transect the metamorphie slice and the peridotite nappe.The diabase dykes generally trend NE-SW and dip almost vertically. Their thicknesses range between 0.5-10 niThe dykes do not transect the ophiolitic melange and the Paleozoic and Mesozoic limestones underlying the melange.No dykes transecting metamorphics and peridotites together are observed.The diabase dykes exhibit crystal sizes varying from fine to medium, starting from cooling borders towards center. Dominant minerals are labradorite, augite, and hornblende. The dykes are subalkaline and tkoleiitic, composition isclose to that of abyssal tholeiites.The intrusion had occurred before the emplacement of the ophiolitic sequence, and most probably in an oceanicenvironment, since diabase dykes transect only the uppermost two unîts and they are close to abyssal tholeiites incomposition.

Abstract: The aims of this work have been to establish tectonic position of the Amanos mountains with respect tothe tectonic units of the surrounding regions. To do that, time and mechanism of emplacement of ophiolites present in theregion were concentrated in the light of their relationship with the neighbouring rocks.A geological map of considerable portion in the region Jias been prepared and, stratigraphy and the lithological unitshas been established in detail.It has been concluded that the ophiolites have emplaced in their tectonic position as large and partly undisturbedthrust slices.Correlation of the lithological units of the Amanos mountains with the Arabian platform sequence has shown thesedimentary sequence of the Amanos mountains has been evolued as the northward extension of the Arabian plate.

Abstract: The area of study includes a part of the North Anatolian fault zone was affected by the Hereynian andAlpine orogenic and epeirogenie movements. As a result, the rocks of the region were folded and faulted. Traces of theHereynian movements were generally obliterated by the orogeny.In Lâdik-Destek region, the folds of either Hercynian-Alpine system have on almost east-west trend, whilethe stress causing these folds was effective an the-south direction.The faults in the area are usually parallel to the fold axes. Moreover, the transversal and oblique faults werealso developed as a secondary system. These secondary faults having a general north-south direction are youngerthan the previous ones.One of the most important structures of the studied area is of course the North Anatolian earth-quake fault.It is highly probable that the fault was formed in an older fracture zone towards the end of Miocene. Total displacement sofar measured along this dextral fault is about 80-85 km. The movement of this presently active fault may bea result of pushing of the Anatolian plate pushed westwards by the Arabian plate.

Abstract: The sedimentary rocks of Mesozoic and Tertiary in the Mudumu-Göynük basin are more than five kilometers in thickness. This sequence is seen overlying granitic rocks in the south; but in the western part of the basinit can be seen either on the granitic rocks -Permo-Triassic aged rock units. First, Mesozoic sedimentation began in fower Jurassic and sandstones of Lias series deposited in the troughs ofthe paleotopography. The sea transgressed in Middle-Late Jurassic and Early Cretaceous and covered lands-earlyJurassic in the area. The eastern and northeastren parts of the basin were relatively deeper than the western part inthis phase. In the Late Cretaceous the basin reached the deepest position entirely and fiyseh sediments were depositedin the whole area. The uplifting of the southern part by the tectonic events in the end of late upper Cretaceous formedan east-west trending shoreline. The regression continued during the Paleocese and this shoreline had regressed tothe north, but shallow marine conditinos prevailed in the of this shoreline. In Early Eocene a new transgression occured, without getting much deeper the sea regressed again in late Eocene and Oligocene. The continental conditions continued until recent in the area. Some lakes formed especially in tectonical depressed areas in Miocene and Quaternary

Abstract: The fragmental volcanic rocks of Seben region (Bolu SE Turkey) are typified by epiclastics in UpperCretaceous, while they are characterized by pyroclastics and autoclastics in Miocene. Epiclastics are well bedded andusually made of crystal and vitric tuffs, but occasional levels of lithic tuffs are also encountered. All of these components were rapidly eroded and transported away from volcanic areas.Pyroclastics consist of local vulcanien breccias and widespread cold pyrociastic flow breccias as well as agglomerates. These pyrociastic succession is overlain by autoclastic breccias. All of fragments have andesitic-basaltic features. The volcanosediments of Miocene in the north-northeast of Seben essentially have been derived from volcanic ventswith phreatic eruptions.

Abstract: The Horoz granodiorite is located in the eastern part of the Bolkardağ. A detorled study of the gra-nodiorite showsthat the emplacement is shallow and has "delayed tectonics" sharacter. The emplacement of the granodiorite has increased thegeothermal gradient of the region. The dyke rocks which are related to the granodiorite are, in the order of emplacement, Biotitebearing tonalite porphyry, Muscovite bearing tonalite porphyry, and Diorite porphyry. The volume of these dykes within thegranodiorite body decrease inversely with time. Some of them are emplaced parallel to the main axis of the granodiorite during theevolution of the body. However, diagonally emplaced dykes are better developed and their directions change with time. 

Abstract: Detailed mineralogical and chemical studies of hydrothermal alteration of the Madenköy, Kutlular, Kotarak Dere, Tunca, Sırtköy and Sarısu volcanogenic sulphide deposits in the Eastern Black Sea ore province of Turkeywere carried out with the aims of obtaining a better understanding of the ore forming environments and establishingfavourable criteria for discovering economic ore bodies. X-ray diffraction and thin-section studies of the footwall andhanging-wall rocks indicate that the orebodies are enveloped by extensive and regular argillic zones which also includesome carbonate minerals such as calcite, dolomite, and siderite. Zeolite minerals were found in volcanics surroundingthe clay zones. However, significance of the Zeolitic zones still remains to be investigated. Continuation of the alteration zone in the hanging-wall rocks demonst-rate that the hydrothermal activity continued for a while after the formation of the orebodies. The most intensive and extensive alteration is, however, foundin the dacitic footwall rocks.The main similarity in all the mineralized areas studied is that the common form of alteration associated with oredeposition is sericitization (including the presence of illite) of the dacitic footwall rocks, which are also commonlyassociated with silicification.The alteration mineral paragenesis suggest that the oresolutions were acidic during the formation of the orebodiesand kaolinite and sericite zones, but became alkaline with declining temperatune towards the end of ore deposition.During this second phaseshemalitization and carbonitization processes took place in the host rocks.Semi-quantitative evaluation of the ``Clay (kaolinite + montmorillonite + illite + sericite)/Feldspar" ratio by aX-ray diffraction method is useful in detecting the jpresenee and intensity of hydrothermal activity related to sulphidemineralization. The Clay/Feldspar ratio as well as regular zonation properties of the alteration minerals can also beused as direction vectors during detailed exploration studies.Geochemical studies of the host rocks support the hydrothermal alteration characteristics determined by themineralogical technigues.

Abstract: Decscriptions of two new genera (Balabania andKurtinia) and their five new species (B. acuticostata, B. elongata, B.densicostata, B. melitenensis, nad K. hemis pherica) found in Maestrichtian of Malatya region have been given.

Abstract: Data about the extension of Sarmatian Sea in North Anatolien is scarce. The Sarmatien beds are already knownfrom İstanbul-Küçükçekmece, Sinop and Pazar areas.In this paper the Elphidiien of Sarmatian beds from Pazar area (figure 1) are described. Nearly all species arecomparable with the other known Elphidiien fauna of the same age. In the fauna the coarse spined species are abundant. Big differences are not observed in a comparision with Middle Sarmatien Elphidiien fauna of Sinop area.In addition to these, a new species is also described. 

Abstract: Two formations, mamed as Eskihisar and Yatağan have been recognized in the study area of Muğla-Yatağan, TurkeyBoth formations are formed from river and lakedeposits.Turgut member of Eskihisar formation contains Anomalomys gatidryi Gaillard, Mastodon (zygolophodon) tapiroides Cuvier and Anchitheriojn, sp. and Sekköy member of same formation contans Paralutra Jaegeri Filhol, Dinotheriumbiganteum Kaup, Brachypotherium brachypus Lartet. The fossils suggest that the Turgut member belongs to Middle Astracian and the Sekköy member to Upper Astracian.Madenler, Bayır and Bozarmut members of the Yatağan formation are of Turolian age according to H. medifenanieinHansel, D. pachygnathus Wagner, Gazella gandriyi Sch.