Türkiye Jeoloji Bülteni

Abstract: Study area is located in Çetinkaya-Divriği Area, Sivas district Eastern Turkey. Petrographical andpetrological studies have been carried out on the intrusive and extrusive rocks of the area.Alkali metasomatism related to Dumluca Intrusion (syenitic - granitic) has effected Güneş Ophiolite rocks andhas caused the scapolitization of basic plagioclases and biotitization of clinopyroxenes. Besides wide spread serpentinization, disseminated - type Ni - mineralization has been observed in ultramafic rocks. It is found that gabbroicrocks show calcalkaline affinity while spilite - diabase rocksshow tholeiitic and calcalkaline trend and they most probably formed in an oceanic environment. Dumluca Intrusion has calcalkaline character. Neogene Volcanics are cqn^sist mostly of basaltic and trachytic rocks and have calcalkaline affinity possibly formed in an island are environment.

Abstract: During the Early Tertiary, the southern part of the Tuzgölü Basin, Ulukışla area and its immediatesurroundings was an ocean from which an ophiolitic complex was emplaced southwards on the Bolkardağ region inLate Crateceous times. From the Tertiary to the present, three different groups of rock assemblages seperated fromeach - other by regional unconformities have developed in this basin in relation to Oceanic, and post oceanic periodsrespectively.These groups are named as Ulukışla, Kılan and Bohçadikmen groups accordingly and, taking litological differences in consideration, they are divided in members and formations.The Ulukışla group, which is the flysch of this oceanic basin comprises islands-arc volcanics and relatedcarbonates and elastics, and various turbiditic sediment deposited in its deeper parts.The Kılan group which represents the molasse of the basin is composed of evaporites, fresh-water carbonatesand terrestrial elastics.Finelly, the Bohçadikmen group, which is the post - oceanic cycle of this through, comprises several forms ofcontinental and lacustrine deposits.At the beginning of the Tertiary, the region was in the form of a closing ocean inwhich an island - arc complex was developing. Progressive closure occured from the north to the south in consequence of collisions of a consecutfve continent with an island - arc and its subsequent collision with a continent.

Abstract: Accumulation of alluvial fan deposits of Köprübaşı, wich is a part of a fluvial sistem in the Köprübaşı basin, is contemperanous with Miocene block faulting. Under the control of this growth - faulting type tectonism, thick fluvial deposits having a wide range of material size from large blocks to clays have deposited. Alluvial fan deposits consist of boulder conglomerate unconformably resting on the metamorphic rocks at the base and,upward the section, Lower conglomerate with relatively small pebbles; sandstone interbedded with mudstone, silstone and conglomerate lenses; middle conglomerate; siltstone - mudstone and upper conglomerate underlying the lacustrine unit consisting of varicolored mudstone at the base and white cherty limestone at the top.These alluvial fan deposits consist of quartz, feldspar, mica garnet, clay, rutile, zircon, tourmaline, ilmenite, magnetite, pyrite, siderite, jarosite and apatite. Clay minerals in alluvial fan deposits are dioctahedral smectite and illite.Dioctahedral smectite has developed usually around small pebbles or grains as vitreous films and its dark green coloris striking. Illite is mostly detrital in origin. In some instances, the illite develops on feldspars as small flakes. Chlorite is detrital or occurs authigenically on biotites.Authigenic clay minerals occurring in the alluvial fan deposits reflect a silica-rich, slightly alkaline groundwater.

Abstract: The present work is based on over 3000 specimens obtained from various localities in the Bilecik,Amasya and Gümüşhane - Bayburt regions, in northern Anatolia. The fossiliferous strata are within the range ofUpper Sinemurian - Lower Pliensbachian, extending up in Toarcian only in the Gümüşhane - Bayburt region. Thefamily Phylloceratidae are represented in these rocks by four genera : Phylloceras, Partschiceras Hantkenicerasand Calliphylloceras. The following species are identified: Phylloceras (Phy`loceras) frondosum, P(P). lipoldi, P(P).hebertinom, P(P). meneghinii, Phylloceras (Zetoceras) zetes, P(Z). pseudozetes, P(Z). bonarellii, P(Z). oenotrium,P(Z). lavizzarii, Partschiceras striatocostatum, Hantkeniceras cf. hantkeni, H. pseudocalais, Calliphylloceras bicicolae.In this first part, the species of Phylloceras are described. The second part, which is in preparation, willdeal with genera Partschiceras, Hantkeniceras and Calliphylloceras.

Abstract: In the Işıklar - Altındağ area (south of Bornova), the rocks of Upper Cretaceous age are representedmainly by limestones and divided from base to top, in the following units :

(1) Forominiferal - rudistid packstone of Late Turonian - Santonian age reflecting shelf lagoonal environment,

(2) Pelagic foraminiferal wackestone of Late Santonian - Early Campanina age indicating conditions of basinal facies,

(3) Bioclastic packstone of Late Campanian - Early Maastrichtian marking foreslope facies,

(4) Foraminiferal - algal packstone of Late Maastrichtian age was deposition in shallow shelf facies conditions.The Upper Cretaceous limestones are vertical and overturned towards northwest in the southeastern part of thestudy area and it always has a faulted contact with detrital rocks including local calcareous shale layers having fossilscharacteristics of Danian.The sea level changes which controlled the depositional environments of the Upper Cretaceous lithofacies unitsindicate a transgression reaching its peak during the Late Santonian and Early Campanian and accompanied by aregression lasting until the end of Late Maastrichtian.

Abstract: Along a belt streching from Cyprus, Southeast Anatolia, Zagros and to the Oman Mountain, a linear trough was formed during Upper Cretaceous as the northern edge of the Arabian Craton subsided and allochthonousophiolite blocks were carried in from the north. From Upper Cretaceous to Miocene, shallow marine sedimentary rocksdeposited over the allochthonous units. However, volcanic activity continued up to the Eocene or Oligocene time alonga second belt loceted to the north of the trough. In this study the geoioy of this second belt, which is called SoutheastAnatolian Ophiolite belt, is examined around the Efgani - Maden region and by using chemical characteristics of thevaiconic rocks, its tectonic evolution is evaluated.In the Ergani - Maden region along the Southeast Anatolian ophiolite belt, crops out as the oldest rocks, Guleman group which consists of gradational peridotite, banded gabbro and basalt units. The Guleman group has beenmetamorphosed under greenschist facies conditions. Chemical composition of the volcanic rocks of the Guleman groupresembles to those of low potassium tholeiites of the midoceanic ridges.Maden group, overlying the Guleman group unconformably with a discontinious conglomerate at its base, iscomposed of basaltic volcanics, volcaniclastics, mudstones and pelagic limostones. In the Mâden group, which is Maastrichtien - Upper Eocene in age, the lower volcanic - sediment unit and the upper volcanic unit have been separated.This group has been metamorphosed under prehnite •• pumelliyite facies conditions. The chemical composition of thevolcanic rocks of the Maden group resembles to those of islaand - arc tholeiites.

Abstract: Zircons enriched from the lower parts of the Gümüşler Formation, forming the lowest unit of theNiğde Massif, have been dated by the U/Pb method. The discordia trajectory, as determined by five nonmagneticsize fractions of the heterogeneous zircons, intersects the concordia at To=2059±77 my and T,=217±4 my. To ageindicates that the paragneisses received elastics from a Proterozoic aged source terrain. T, age suggests that apossible early Alpine (Kimmerian) event may have affected the paragnesses. However there is se far no geologicalsupport for such an event and this age is open for further interpretations.

Abstract: Menderes massif rocks, outcropping in Selimiye and Beşparmak region, are composed of units formedat the interval of Precambrian to Triassic. Massif is composed of Beşparmak formation of Precambrian age, Kılavuz formation of Silurian age, Aktaş formation of Devonian to Carboniferous age and Anitas formation of Triassicage. Menderes massif, having different metamorphic facies, is of sedimentary origin. Beşparmak formation has beenmetamorphosed by Early Caledonian orogeny while other formations, Kılavuz, Aktaş and Anitas, have been metamorphosed by Early Alpine orogeny. There is angular unconformity between the Beşparmak and Kılavuz formations,whereas there are disconformities between other formations.

Abstract: The Makkah inner ring road project involves construction of four-vehicular tunnels and connectionroads around Holy Kabe in Saudi Arabia. The tunnels are horse-shoe shaped in cross section, double-tube, and ofvarying lengths. ,Quartz diorite of Preeambrian age consitütes the major bedrock along tunnel MIT-2, which is located approximately 1 km southeast of Kabe» The bedrock is frequuently crossed by felsite and dolerite dykes. Both the bedrock and the dyke rocks are strong to very strong.The joints developed within quartz diorite give rise to a large and/or very large blocky structure to the rock.The joints are generally widely spaced having tight and/or narrow apertures, and rough to planar surfaces. Theycontain neither infillings nor water.In order to provide a basis for tunnel support design, the rock mass quality is determined as «weak» at the tunnel portals and «good» away from the portals. It is further recommended that at the tunnel portals rockfall and othersimilar incidents may be avoided by the application of systematic bolting, wire meshing, and shotcreting. Awayfrom the portals random bolting and shotcrete application may be sufficient.