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    SEDIMENTOLOGY AND MINERALOGY OF LATE MIOCENE PALEOSOLS AND CALCRETE RICH SEDIMENTS IN THE WESTERN PART OF CENTRAL ANOTOLIAN VOLCANIC PROVINCE (CAVP), TURKEY
    (Int Scientific Conference Sgem, 2008) Guel, Ali; Kerey, Erdal; Ozcan, Selcuk
    The Dogantarla-Aksaray area is situated in western part of the CAVP. This province contains nine (9) different ignimbrite levels, for which a Late Miocene age is indicated by vertebrates as well as K/Ar ages of I I to 2.8 Ma (Viereck-Goette et al 2006). However, most paleosol and calcrete occur within the interval of 7.6 to 2.8 Ma (Gurel and Kadir, 2006). Among this ignimbrite levels, fluvial and lacustrine sediments are found, so called Bayramhacili Formation of western CAVP consist of alternation of typical red conglomerate, sandstone, mudstone, diatomite-limestone and intercalated with several red colored paleosol and calcrete levels. Paleosols and calcrete occurs in sequences with in the whole stratigraphic profile. It is recognized that they are aridisols, inceptisols, locally associated with, oxisols and vertisols, according to the soil taxonomy (Soil Survey Staff, 1992). Paleosols and calcrete of Dogantarla-Aksaray area are characterized by thin section, X-ray diffraction (XRD), and scanning electron microscopy (SEM). Paleosols and calcrete are composed of feldspars, quartz, opal-CT, amphibolites, serpentine, and talk are dominant in the whole profile. They are accompanied by smectite, chlorite, palygorskite, and illite, locally associated with accessory sepiolite. The grains are cemented clay minerals or iron oxide, calcite, and gypsum. The calcite content is attributed mainly to calcrete building, which has a sub-parallel relationship with calcrete, and occurs mainly in the interlayer space of smectite. The clay content decreases with increase in calcite. The non-carbonate fraction is, therefore, quite rich in aluminosilicate minerals. Thus, the presence of an inverse relationship between CaO and other oxides may correspond to an inverse relationship between calcite and other minerals. Minerals such as palygorskite, chlorite, and gypsum are enriched in some levels of the profile. In addition that authigenic smectite, palygorskite and calcite formed as a result of the calcretion of paleosol and calcrete units in alkaline conditions, high Si and Mg activity and low Al; Paragenesis and textural features of the minerals of the fluviallacustrine sediments determined in the study area indicate that precipitation should have been occurred due to climatic fluctuations ranging from arid, semi and to wet conditions.