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Öğe Differentiation of Neotethyan ophiolitic melange and an approach revealing its surficial chromite deposits using ASTER image and spectral measurements (Sivas/TURKEY)(SPIE-INT SOC OPTICAL ENGINEERING, 2010) Kavak, Kaan Sevki; Tore, Yavuz; Temiz, Haluk; Parlak, Osman; Cigla, Hande; Yakan, Mustafa; Michel, U; Civco, DLThis work is aimed at differentiation of ophiolitic melange rocks which were outcropped 60 km far from Sivas city center using image processing and spectral measurement methods. These rocks are known as oceanic crust remnants which were made up of different rocks. Turkey hosts several paleo-oceans and their realms in Alpine-Himalayan orogenic belt. The Neotethyan ophiolites in Turkey are characterized by supra subduction zone (SSZ-type) ophiolites. Ophiolitic rocks are generally coloured with greenish tones and human eye could not separate these tone differences. But satellite images such as ASTER can realize these separation utilizing spectral enhancement methods such as classification and decorrelation stretching. Chromite is a valuable mineral and is formed in only ophiolitic rocks. Dunites and harzburgites named as also ultramafic tectonits of ophiolitic serie mainly contain these deposits in study area. In this study, an approach was also realized to find target regions of chromite deposits with the aid of spectral methods. Spectral measurements were realized to determine boundaries between different melange rocks using spectroradiometer. Reflectance curves collected from field and laboratory analysis were evaluated together and compared with ASTER image of the study area respectively. A detailed differentiation generally was accompanied with petrographic and geochemical analyses.Öğe Geochemical characteristics of ophiolitic rocks from the southern margin of the Sivas basin and their implications for the Inner Tauride Ocean, Central-Eastern Turkey(TAYLOR & FRANCIS LTD, 2017) Kavak, Kaan Sevki; Parlak, Osman; Temiz, HalukNumber of dismembered ophiolite bodies crop out between Sivas and Malatya on the top of the Eastern Tauride platform in the central-eastern Turkey. One of which at the southern margin of the Sivas basin in the Tecer Mountain area comprises melange and the lower part of an oceanic lithospheric section on top of the Tauride platform. The mantle tectonites are characterized by variably serpentinized harzburgites and dunites, and are intruded by numerous isolated dykes. The gabbroic cumulates consist of olivine gabbro, gabbro and gabbronorite. The major and trace element geochemistry of the mafic cumulate rocks suggests that the primary magma was compositionally similar to those observed in modern island-arc tholeiitic sequences. The isolated dykes are exclusively basaltic in composition and display geochemically two distinct subgroups: Group I is represented by high TiO2 (.87-1.47 wt.%) and other incompatible elements, whereas Group II is characterized by low TiO2 (.36-.66 wt.%) and other incompatible elements. The Group I isolated diabase dykes have flat to slightly LREE-depleted profiles (La/Yb N = .32-.79), whereas the Group II isolated diabase dykes are more depleted in general and have a LREEdepleted character (La/Yb N = .19-.49). This suggests that the isolated dykes were derived from an island arc tholeiitic magma (Nb/Y = .02-.05) with different degrees of partial melting (Group II > Group I) and relatively high oxygen fugacity in intra-oceanic subduction zone. The ophiolitic rocks in the study area may well be compared with the Divrigi ophiolite to the southeast. All the evidence suggests that the isolated dykes in the Tecer Mountain area differ from the alkaline isolated dykes cutting the Divrigi ophiolite. Since the late stage dykes (similar to 76 Ma) in the Divrigi area are alkaline, the tholeiitic isolated dykes in the present study should have been emplaced prior to the alkaline dykes during Late Cretaceous SSZ-spreading (similar to 90 Ma) within the Inner Tauride Ocean.Öğe Geochemistry of the Middle Miocene Collision-related Yamadagi (Eastern Anatolia) Calc-alkaline Volcanics, Turkey(SCIENTIFIC TECHNICAL RESEARCH COUNCIL TURKEY-TUBITAK, 2009) Ekici, Taner; Alpaslan, Musa; Parlak, Osman; Ucurum, AliMajor, trace element and K-Ar age determinations are reported for a suite from the Yamadagi volcanics in the Eastern Anatolia. The exposed rocks mainly consist of medium-potassium calc-alkaline basaltic andesites, andesites and dacites. Petrographical data exhibit disequilibrium mineral textures, such as resorption of the ferromagnesian phases, clinopyroxene-mantled orthopyroxene, and sieve-textured plagioclases. The Yamadagi volcanics have a calkalkaline character, and trace element characteristics exhibit that the volcanics resemble subduction zone volcanics and/or volcanics assimilated by continental crust. K/Ar age determinations show that the Yamadagi volcanics were formed during the 12 +/- 0.5 - 15 +/- 0.5 Ma time interval. Geochemical characteristics of these volcanics can be attributed to complex petrogenetic processes, including magma mixing and crustal assimilation along with fractional crystallization.Öğe Geochemistry of the Pliocene basalts erupted along the Malatya-Ovacik Fault Zone (MOFZ), eastern Anatolia, Turkey: Implications for source characteristics and partial melting processes(ELSEVIER GMBH, URBAN & FISCHER VERLAG, 2007) Ekici, Taner; Alpaslan, Musa; Parlak, Osman; Temel, AbidinThe study area is located on the middle sector of the Malatya-Ovacik Fault Zone (MOFZ) in the eastern Anatolia. Four basaltic flows from bottom to top, which are tholeiitic in character and intercalated with Pliocene sedimentary rocks, were erupted along this fault zone. Chemical compositions of these flows reveal some differences between the first flow and others in terms of high-field strength elements (HFSEs) (e.g. Ti, Zr, Nb). Limited variations in compositions within the first flow and upper flows suggest a limited fractionation range. Trace-element patterns exhibit that all the flows have similar and OIB-like patterns without positive peak at Pb and a trough at Nb-Ta, indicating minimal or no crustal contribution. Rare-earth element (REE) patterns indicate that the first flow has flat patterns with negative Eu anomaly, whereas the upper flows have variable enrichments in LREE and depletions in HREE. La/SMN, Dy/Yb-N and Zr/Y ratios exhibit that the degree of partial melting decreases from the first flow to upper flows. Higher values of La/Yb-N ratio for the upper flows and depletions at Y and Yb on the trace-element patterns suggest the presence of garnet as a residual phase, which imply that the depth of partial melting took place solely in the garnet-stability field. OIB-like trace-element patterns and trace-element ratios (e.g. La/Nb, Ce/Y and Zr/Nb) emphasize that the melts forming the Arguvan basalt were originated from the asthenospheric mantle rather than the lithospheric mantle. (c) 2006 Elsevier GmbH. All rights reserved.Öğe Origin and tectonic significance of the metamorphic sole and isolated dykes of the Divri?i ophiolite (Sivas, Turkey): Evidence for slab break-off prior to ophiolite emplacement(2006) Parlak, Osman; Yilmaz, Hüseyin; Boztu?, DurmuşThe Late Cretaceous Divri?i ophiolite of east-central Anatolia comprises, from bottom to top, an ophiolitic mélange, metamorphic sole and remnants of oceanic lithosphere. The ophiolitic mélange has been thrust onto the Lower Carboniferous-Campanian Munzur Limestone (Tauride platform), and is in turn tectonically overlain by the metamorphic sole. The metamorphic-sole rocks are represented by amphibolite, plagioclase amphibolite, plagioclase-amphibole schist, plagioclase-epidote-amphibole schist and calc-schist. The oceanic-lithosphere remnant exhibits a complete section, excluding volcanic rocks, comprising mantle tectonites, ultramafic to mafic cumulates, isotropic gabbros and sheeted dykes. Isolated dykes intrude the metamorphic sole and mantle tectonites at different structural leve!s. The metamorphic-sole rocks beneath the Divri?i ophiolite can be divided into two groups with distinct geochemical features. The first group is tholeiitic (Nb/Y=0.07-0.18), whereas the second group is alkaline (Nb/Y=1.77-3.48) in chemistry. Chondrite-normalized REE patterns, N-MORB-normalized spider diagrams and tectonic discrimination diagrams suggest that the protolith of the first group was similar to island-arc tholeiitic basalts, whereas the protolith of the second group was more akin to within-plate alkali basalts. The isolated dykes cutting the metamorphic sole and the mantle tectonites exhibit alkaline (Nb/ Y=0.68-2.11) character and are geochemically similar to within-plate alkaline basalts. The geochemical evidence suggests that the Late Cretaceous Divri?i ophiolite formed in a suprasubduction zone tectonic setting to the north of the Tauride platform. During intraoceanic subduction/thrusting, the IAT type and seamount-type alkaline basalts were metamorphosed and accreted to the base of the Divri?i ophiolite. The alkaline isolated dykes were probably the result of late-stage magmatism fed by melts that originated within an asthenospheric window due to slab break-off, shortly before the emplacement of the Divri?i ophiolite onto the Tauride platform to the south. Copyright © TÜBİTAK.Öğe Origin and tectonic significance of the metamorphic sole and isolated dykes of the Divrigi ophiolite (Sivas, Turkey): Evidence for slab break-off prior to ophiolite emplacement(SCIENTIFIC TECHNICAL RESEARCH COUNCIL TURKEY-TUBITAK, 2006) Parlak, Osman; Yilmaz, Huseyin; Boztug, DurmusThe Late Cretaceous Divrigi ophiolite of east-central Anatolia comprises. from bottom to top. an ophiolitic melange, metamorphic sole and remnants of oceanic lithosphere. The ophiolitic melange has been thrust onto the Lower Carboniferous-Campanian Munzur Limestone (Tauride platform), and is in turn tectonically overlain by the metamorphic sole. The meta morphic-sole rocks are represented by amphibolite, plagioclase amphibolite, plagioclase-amphibole schist, plagioclase-epidote-amphibole schist and calc-schist. The oceanic-lithosphere remnant exhibits a complete section, excluding volcanic rocks, comprising mantle tectonites, ultramafic to mafic cumulates, isotropic gabbros and sheeted dykes. Isolated dykes intrude the metamorphic sole and mantle tectonites at different structural levels. The metamorphic-sole rocks beneath the Divrigi ophiolite can be divided into two groups with distinct geochemical features. The first group is tholeiitic (Nb/Y=0.07-0.18). whereas the second group is alkaline (Nb/Y=1.77-3.48) in chemistry. Chondrite-normalized REE patterns, N-MORB-normalized spider diagrams and tectonic discrimination diagrams suggest that the protolith of the first group was similar to island-arc tholeiitic basalts, whereas the protolith of the second group was more akin to within-plate alkali basalts. The isolated dykes cutting the metamorphic sole and the mantle tectonites exhibit alkaline (Nb/Y=0.68-2.11) character and are geochemically similar to within-plate alkaline basalts. The geochemical evidence suggests that the Late Cretaceous Divrigi ophiolite formed in a suprasubduction zone tectonic setting to the north of the Tauride platform. During intraoceanic subduction/thrusting, the IAT type and seamount-type alkaline basalts were metamorphosed and accreted to the base of the Divrigi ophiolite. The alkaline isolated dykes were probably the result of late-stage magmatism fed by melts that originated within an asthenospheric window due to slab break-off, shortly before the emplacement of the Divrigi ophiolite onto the Tauride platform to the south.Öğe Sivas havzası Güney kenarının ASTER uydu görüntüleriyle incelenmesi ve spektral kütüphanesinin oluşturulması(2010) Kavak, Kaan Şevki; Konya, Hande; Töre, Yavuz; Parlak, Osman; Temiz, Hakan; Yakan, Mustafa[Abstract Not Available]
