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    Geology and mineralogy of Late Miocene clayey sediments in the southeastern part of the Central Anatolian Volcanic Province, Turkey
    (CLAY MINERALS SOC, 2008) Guerel, Ali; Kadir, Selahattin
    Late Miocene clayey sediments were deposited in lake-margin and shallow-lake environments of the southeastern Central Anatolian Volcanic Province (CAVP). Yellow to red mudstone, alternating with thin beds of conglomerate and sandstone in the Mustafapasa Formation, is overlain by altered white Cemilkoy ignimbrite. Grain size fines upward in each sequence (conglomerate, sandstone, and mudstone). The occurrence of reddish coloration upward, ripple marks, desiccation cracks, plant rootlets and remnants, and the development of initial-stage paleosols in association with smectite reveal that the area underwent alternating periods of siliciclastic and volcaniclastic sediment Supply (wet) and drying, Micromorphologically, the development of spongy smectite in mudstone of the Mustafapasa Formation and vermiform kaolinite in the Cemilkoy ignimbrite on resorbed detrital feldspar and devitrified glass reveals in situ precipitation driven by dissolution and precipitation mechanisms. In addition, alteration of these sediments may have resulted in the depletion of soluble alkaline elements, such as Ca, Na, and K, from the ignimbrite downward into the Mustafapasa Formation. Alternatively, the leaching of these elements - due to the hydrologically open system of the lake environment - may have resulted in the enhancement of Al+Fe/Si-favored precipitation of kaolinite in an acidic environmental condition, namely, of the altered Cemilkoy ignimbrite at the top of the profile of the Mustafapasa Formation, and of smectite in an alkaline setting within lower-level sediments where carbonate minerals were lacking. The coexistence of smectite with accessory illite indicates that illitization occurred via release of K and Al during excess desorption of feldspar. Large Ni and Co values in mudstone samples, and Fe oxidized and partly chloritized pyroxene and hornblende, indicate that the basin was also affected by ophiolite-related supply.
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    Sedimentological characteristics of the Cukurbag formation deposited along the Ecemis Fault Zone, Central Anatolia, Turkey
    (SPRINGER INDIA, 2007) Guerel, Ali; Ciftci, Emin; Kerey, I. Erdal
    The Oligocene Cukurbag Formation, deposited within a long narrow basin surrounded by the Aladag, Ulukisla, and Nigde metamorphic Groups, consists of conglomerate, sandstone, siltstone, mudstone, marl, mudstone-gypsum successions. A number of analytical methods including morphological, mineralogical, and chemical techniques were employed to investigate the sedimentological characteristics of the formation. According to the grain size analyses, sediments of the formation are very poorly sorted with strong positive to near symmetrical skewness. The analyses show that irregular flow regime should have occurred during sedimentation of the 1;ukurbag Formation. These sediments comprises mainly of quartz, feldspars, calcite, clinopyroxene, and Fe-oxides. Common clay minerals include smectite, chlorite, and kaolinite. The chemical analyses carried out on the samples representing the bottom to the top of the formation indicated that SiO2, Al2O3, K2O, and P2O5 contents are low compared to the world mudstone averages. However, MgO, CaO, and C contents are comparatively high. Four measured profiles showing the distribution of principle facies within the formation are prepared. Based on the profile analyses, seven distinct lithological facies were distinguished that include massive conglomerate, bedded conglomerate, stratified sandstone, cross-bedded sandstone, laminated siltstone, massive mudstone-marl, and laminated mudstone-gypsum. This study suggests that the sediments of this formation must have been reworked material transported from unknown distances and deposited in an alluvial fan-braided stream and lacustrine environments.