Türkiye Jeoloji Bülteni

Abstract: An area of approximately 700 km2 at the SW of Kiziİcaha am, in Central Anatolia was studied volcanologi ally andpetrologi ally. The area is covered by volcanic rocks and Tertiary sediments. Metamorphic rocks are prpesent at the base. Theregion is near some plate margins at N and SE. Volcanic rocks probably started to accumulate in Lower Tertiary andaccumulation ended before Early Pliocene. There is a lava plateau which formed by aa and blocky lava at the base and productsof Aluç and Binkoz Volcanoes overlie them. These are monogenetic and monocentric volcanoes. A small caldera formed at BinkczVolcano. Explosion indexes of these volcanoes are near 10. During the Middle Miocene, Ağacın Volcano formed, whose explosionindex is 60. A pyroclastic breccia, an ash flow, a vulcanian breccia and Başören Lava erupted from here. Crater of the volcano ispluged by a lava dome. During this period, laaharic epielastic breccias generated on the southern flanks of ancient volcanoes.Lavas belonging to this period are calcalkaline in character. But this magnesoferric lavas are different from the previous ferricproducts. The difference of magma from the first period are lower water content and outpourability with exposive eruptionsbecause of the fractionation under more plastic cover. Quartz occurs in norms and hypersthene in modal compositionsof all lavas. Formation of calcalkaline series hypothesis with high water content near old subduction zones is alsovalid for our study area. 

Abstract: The area under investigatlon covers the central part of Murat Dağı (Murat Mountain). The oldest rock unit of thearea is the Aşağı Belova Formation of Jurassic age, being composed of the Yargediktepe Member and the Çiçeklikaya Dolomiticlimestone Member. Both members have lateral and vertical gradational contacts. The Yargediktepe Member consists of tightlyfolded metasandstone and metaslltstone of different chemical compositions, subjected to a greenschist metamorphism in a gradenot higher than quarter albite-muscovite chlorite subfacies. A§ağı Belova Formation is tectonically overlain by the OphioliticMelange of Late Cretaceous age consisting of sedimentary (cherty ltmestone, radiolarite); magmatic (peridotlte, spilite, tuff) andmetamorphic (schist; marble) rocks of varying dimensions. The metamorphic constituents of the melange are rich in aluminacontent with a fair amount of sillca. Their metamorphism is of the Barrov type indicatlng a staurolite -Almandine subfacies of theAlmandine -Amphibolite facies. The chemical compositions of the magmatic rocks of the ophiolitic melange indicate the existenceof two different rock assemblages in the melange. Ne, increase in volume has been observed in these rocks. During theserpentlnization of the peridotites.Chemical compositions of Baklan Granite of Paleocene age (Monzogranite) and Karacahisar volcanics of Middle Miocene age (rhyolite, rhyodacite and rhyolitlc tuff) may indicate that these rocks are the products of magma types some ofwhose properties are alike and others of whic are unalike. The sedlmentary rocks of Tertiary age in the area are made upof coarse clastics.Radloactive age measurements made by K-Ar and Rb/Sr methods gave the following results. The age of the folding andmetamorphism of the Yargediktepe Member Is 126,5+-11 m.y. (Late Jurasslc -Early Cretaceous); the age of the latesthomogenizatlon of the metamorphic mass in the melange on the hasis of the Rb/Sr method is 70,4+-3 m.y. (Maestrlchtlan); the ageof the crystalllzatlon of the Baklan Granite Is 52+-7 m.y. (Paleocene -Eocene); the age of the Karacahisar volca-nics ranges from16,9+-0,2 to 20,9+-0,5 m.y. (Middle Miocene). 

Abstract: This work is concerned with the quantitative eleetron microprobe analysis of Pb-Bi sulfosalts, theiridentification and relation to other sulfosalts, and examination of their optical properties. The specimens are from theQueen Hill area of Zeehan, Tasmania.Electron microprobe analysis has confirmed the presence of two sulfosaits: a Bi-rich phase Pb3Bi5Ag2Sb S1 3)fand a Bi-poor phase (Pb9Bi8Ag Sb2S24) corresponding to gustavite and kobellite respectively.There are no characteristie differences in the optical properties of the two Pb-Bi phases. They are constantlyintergrovm with each other and frequently associated with pyrite, stannite, galena and bismuthinite. Texturally thesulfosalts form complex intergrowths with each other whieh are believed to be due to exsolution. They show replacement features of older minerals thus, paragenetically, are among the last phases to have crystallised.Analyses of some selected minerals are also carried out, namely galena, stannite, bismuthinite, tetrahedrite anda sulfoantimonide mineral which thought to be related t o freieslebenite.Examination of the minör element content of galena indicates that the ore field around Zeehan is of unusuallyhigh temperature, which is consistent with the field`s anomalous geochemiçal properties.

Abstract: Four separate fault zones have been distinguished on the basis of author`s recent observations made in theregion between Lake Van and Iranian border, and it is also deduced that one of those, in particular, no. I in the northcould be an extention of the North Anatolian Fault Zone.Çaldıran Fault which caused Çaldıran Earthquake of 24 th November 1976, indicates a new dislocation parallel to theprincipal fault (North Anatolian Fault having similar strikeslip and right-lateral motion.Wide spread ophiolite complex of the area investigated is not, in fact, so complex as has been so far noted. it exibitsrather regularly - layered structure. This complex sequence (melange) which is, composed primarily, of serpentinites,radiolarites, submarine volcanics and their related tuffs, red coloured limestones and marls and variegated shales,place to place, it contains blocks of metamorphics and Permian limestones of various sizes. in other words the metamorphicrocks and the Permian limestones are also the elements of this complex. All of these rocks have constituted a "subductionmelange" in the same subduction zone.