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    Diagenesis and low grade metamorphism of Karakaya complex units in the NW Anatolia
    (Hacettepe Universitesi Yerbilmleri, 2009) Tetiker, Sema; Yalçin, Hüseyin; Bozkaya, Ömer
    The aim of this study is contribute to discussions concerning the formation of the Paleotethyan Permo-Triassic Karakaya Complex by revealing the diagenetic-metamorphic properties of the units within the Sakarya Composite Terrane in Northwestern Anatolia. The Nilüfer unit from the Lower Karakaya unit is represented by rocks of blueschist in the lower parts and greenschist facies in the upper parts. The Upper Karakaya unit has limestone blocks, made up of psammite, pelite and carbonate rocks associated with volcanics. In NW Anatolia, various mi- nerals have been determined, in order of abundance, as phyllosilicates (illite, chlorite, stilpnomelane, smectite, kaolinite, C-S, I-S, C-V), feldspar, calcite, quartz, dolomite, pyroxene (augite, Ti-augite), amphibole (hornblende, glaucophane, tremolite/actinolite, anthophyllite), hematite, epidote and goethite in the Lower Karakaya unit, and quartz, phyllosilicates (illite, chlorite, I-S, C-V, C-S, I-C, kaolinite, vermiculite, smectite), calcite, dolomite, feldspar, epidote, augite, hornblende, natrolite, hematite and goethite in the Upper Karakaya units. Trioctahedral chamozitic chlorites and phengitic dioctahedral illites have, respectively, IIb polytypes and 2M1+1M +1Md in the Nilüfer, Orhanlar and Çal units. Kübler index (KI) and Arkai index (AI) data correspond to low-grade anchizone and epizone for the Nilüfer Unit, high grade diagenesis for the Hodul Unit, high grade diagenesis and low grade anchizone for the Orhanlar Unit, and low grade diagenesis for the Çal Unit. The b0 values of illites show as moderate to high for the Lower Karakaya units, but mostly as a moderate pressure facies series for the Upper Karakaya units. According to the textural features, mineral associations, clay/phyllosilicate transformations, typical index minerals and crystallochemical data of phyllosilicates, the Lower Karakaya units were formed in high pressure/low temperature conditions in a compressional basin, whereas the Upper Karakaya units reflect the diagenetic/metamorphic characteristics of an extensional basin dominated by low heat flow.
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    Origin of phlogopite occurrences related to ultramafic plutonic rocks in the sivas-yıldızeli area
    (Hacettepe Universitesi Yerbilmleri, 2016) Yalçin, Hüseyin; Bozkaya, Ömer; Yeşildağ, Hülya
    The different two series/associations as Upper Cretaceous Karakoç plutonics and Paleocene felsic plutonic rocks belonging to Central Anatolian Plutonics are present in the Yıldızeli area. Karakoç plutonics consist of ultramafic and mafic rocks and are of transition into each other. Phlogopite mineralizations related to Karakoç plutonics are surrounded by Yıldızeli metamorphic rocks and cut by felsic plutonic and vein rocks. Garnet-scapolite-epidote-phlogopitic pyrometasomatic occurrences are seen within the zones intruded by dikes. Packages of phlogopite plates (1-5 cm) are surrounded by a zone (10-15 cm) with pyroxene and/or hornblendes in which garnet, epidote and scapolite layers and/or lenses are found in places. Phyllosilicates are formed of smectite, C-S (chlorite-smectite), chlorite and P-V/I-V (phlogopite-vermiculite/illite-vermiculite) in the Karakoç plutonics, smectite, chlorite and I-S (illite-smectite) in the mafic plutonic rocks, smectite in the felsic plutonic rocks, and 1M Fe-Al phlogopite, smectite, I-V/P-V and S-V (smectite-vermiculite) in the pyrometasomatic rocks. Phlogopite components as Mg/(Mg+Fe) are 0.74 for phlogopite and 0.67 for P-V. Hornblende, scapolite and garnet from the other silicate minerals are Ca-Na-K magnesian hastingsite, mizzonite and grossular in compositions, respectively. Total trace element concentrations decrease phlogopite-P-V-garnet-hornblende-scapolite trend. The distributions of chondrite-normalized trace and rare earth elements (REE) were clearly decreased from garnet-hornblende-scapolite–phlogopite towards P-V and mineral patterns distinguish from each other and also show a clear differentiation/fractionation. ?18O values of phlogopite and P-V have lower than those of mantle and MORB; whereas they are similar to those of continental originated magmatic rocks. ?18O and ?D concentrations of phyllosilicate minerals suggested that the phlogopite and P-V have respectively hypogene and supergene origins. The decreasing ?D and increasing ?18O values indicate phlogopitization trend, whereas those of increasing ?D and decreasing ?18O sign vermiculitization trend. On the other hand, according to granitoid rocks, reflecting initial values for isotopically fractionation, formation temperatures of phlogopite and P-V were obtained as ~ 280 and ~130 °C, respectively that phlogopite and P-V minerals are thought to be pyrometasomatic rather than magmatic origin. In addition, phlogopites are sometimes undergone vermiculite type of negative transformations passing into P-V interphases. © 2016, Hacettepe Universitesi Yerbilmleri. All Rights Reserved.
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    The mineralogy of Paleozoic rocks from the Amanos region, Turkey
    (Hacettepe Universitesi Yerbilmleri, 2009) Bozkaya, Ömer; Yalçin, Hüseyin; Kozlu, Hüseyin
    In the Amanos region, a Precambrian-Triassic sequence is formed by mainly clastic and carbonate rocks and their very low-grade metamorphic equivalents that contain calcite, dolomite, quartz, feldspar, goethite and phyllosilicate (illite, chlorite, kaolinite, paragonite, paragonite-muscovite, smectite, illite-chlorite (I-C), chlorite-vermiculite (I-V) and chlorite-smectite (C-S)) minerals. Of these, maximum quantities are reached for quartz and feldspar in Zabuk and Sadan, calcite in Hasanbeyli and Cudi, and dolomite in the Koruk formations. Illite is abundantly found in all units, whereas there are increases in the chlorite contents in the Sadan, Sosink and Hasanbeyli formations, a minor amount of kaolinite in the Zabuk, Koruk and Seydisehir formations, I-C in the Sadan, Seydişehir and Ki{dotless}zlaç Formations, C-V in the Seydişehir, Ki{dotless}zlaç and Akçadag formations, and C-S in the Sadan and Sosink formations. Paragonite and paragonite-muscovite are observed only in the Ki{dotless}zlaç and Akçada? formations. Illites and IIb chlorites have mostly anchimetamorphic and partly late diagenetic and epimetamorphic crystallinity degrees. The b0 parameters of the illites are distinctive for units, and higher values are measured for Seydisehir and older units, whereas lower values are found for the younger units (Ki{dotless}zlaç, Hasanbeyli and Cudi). 2M1 illites are observed in all units, but 1M in Precambrian-Ordovician units (Sadan, Zabuk, Koruk, Sosink and Seydişehir) and 1Md in Devonian (Hasanbeyli) and in Precambrian-Ordovician units, in smaller amounts. Feldspar also increases in the chlorite and chloriteinterlayered minerals-bearing levels that are related to volcanic feeding, and 1M polytype accompanies this association. The mineralogical properties have no regular distribution based on thickness and geological age, and sudden changes are observed between some of the formations, which is an indication related to mostly source rock, tectonic setting and geodynamic evolution rather than to degrees of diagenesis/metamorphism. In the sequences representing passive margin depositional environments, the Precambrian Sadan formation and Ordovician Bedinan and Devonian Akçada? formation have the mineralogical characteristics of convergent-and extensional basins, respectively. The lower Paleozoic parts of the sequence are similar to equivalents in the Eastern Taurus Autochthon (Geyikda?i Unit) with regard to mineralogic features, but its Devonian-Triassic part is different from equivalent parts of the units of the Tauride Belt and Southeastern Anatolian Autochthon in the Hazro region.