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    Geology of Late Miocene clayey sediments and distribution of palaeosol clay minerals in the north-eastern part of the Cappadocian Volcanic Province (Araplı-Erdemli), central Anatolia, Turkey
    (2013) Selahattin Kadir; Ali Gürel; Hülya Senem; Tacit Külah
    The study area is situated in the Araplı-Erdemli (Kayseri) area in the north-eastern part of the Cappadocian Volcanic Province (CVP), central Anatolia. The Late Miocene series comprises lacustrine and fluvial deposits interbedded with ignimbrites and lava flows. The Late Miocene Mustafapaşa member of the Ürgüp Formation comprises yellow to red mudstone that alternates with thin sandstone beds in the north-eastern part of the CVP. This unit continues upward through the Cemilköy ignimbrite palaeosol layers (comprising altered Cemilköy ignimbrite, vertisol and well-developed palaeosol layers), the Gördeles ignimbrite and red palaeosol layers, and includes two fallout levels; it is overlain by the Kızılkaya ignimbrite. The Mustafapaşa member is dominated by smectite±illite±chlorite, whereas the altered Cemilköy ignimbrite is predominantly kaolinite±smectite±chlorite. The underlying lower level of the Gördeles ignimbrite contains palaeosol layers, and continues upward through smectite-dominated layers. Alteration of feldspars and glass shards in the Cemilköy and Gördeles ignimbrites resulted in the depletion of soluble alkaline elements (such as Ca, Na and K) from these ignimbrites downward to the Mustafapaşa member, and palaeosol levels (Bayramhacılı member) in the Araplı area favoured precipitation of smectite in an alkaline environment. However, the absence of these elements in these ignimbrites may have resulted in the enhancement of Al+Fe/Si-favoured precipitation of kaolinite in an acidic environment. Conversely, palaeosol of the Erdemli area consists of smectite±illite±chlorite. Micromorphologically, flaky smectite rims illite in both the Araplı and Erdemli areas and this can be explained by the release of K and Al during desorption of feldspar. Additionally, higher Ni, Co and Cr2O3 values in the mudstone samples of the Mustafapaşa member and palaeosol levels, the presence of iron oxide and partially chloritised pyroxene and hornblende, together with ophiolitic and metamorphic grains, indicate that the basin also accumulated ophiolitic and metamorphic rock fragments in its sediment supply. This suggests that the Araplı area in the southern part of the CVP has undergone erosion, and that the present-day Erdemli area was close to the shallow-lake depositional environment of the northern part of CVP.
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    Geology, mineralogy, geochemistry, and depositional environment of a Late Miocene/Pliocene fuviolacustrine succession, Cappadocian Volcanic Province, central Anatolia, Turkey
    (2014) Ersel Göz; Selahattin Kadir; Ali Gürel; Muhsin Eren
    This paper investigates the mineralogy, geochemistry, and depositional environment of Late Miocene/Pliocene fuviolacustrine deposits, including multiple ignimbrite levels and andesitic and basaltic lavas, within the Cappadocian Volcanic Province (CVP) of central Anatolia, Turkey. Palaeosols and calcretes formed within these terrestrial sedimentary rocks under near-surface or surface conditions. Te palaeosols are composed predominantly of smectite ± illite with feldspar, quartz, calcite, opal-CT, and amphibole, and the calcretes mainly of calcite with minor feldspar, quartz, and accessory smectite ± palygorskite. Te palygorskite occurs on and between the calcite crystals in the calcretes and at the edges of smectite fakes within the palaeosols, indicating an in situ formation from evaporated alkaline water rich in Si and Mg and poor in Al under arid or seasonally arid climatic conditions. In the palaeosols and calcretes, negative Ba, Nb, Ce, Sr, and Ti anomalies and an enrichment of light rare earth elements relative to medium rare earth elements and heavy rare earth elements, with a distinct negative Eu anomaly, likely refect the alteration of feldspars and amphiboles in the ignimbrite. Te alteration of the ignimbrites caused the depletion of SiO 2, Al2O 3 +Fe 2O 3 , TiO 2, and K2O through the precipitation of smectite ± illite in the palaeosols and CaO in the form of calcite in the calcretes. Te δ 18O values of the calcretes and limestones range from –8.71‰ to –10.71‰, which are mainly related to the involvement of high-elevation meteoric water, whereas the δ 13C values for the same rocks vary between –1.97‰ and 5.71‰. Te positive δ 13 C values for the limestones refect calcite precipitation in isotopic equilibrium with meteoric water in a lake . Te slightly negative δ 13 C values of the lacustrine limestone carbonates may indicate precipitation from a relatively thick water column and an infow of surface or groundwater through the ignimbrites with high Ba/Sr values. Conversely, the calcrete δ 13C values (3.0‰ to 4.97‰) may suggest a pedogenic origin with low plant respiration rates and a predominance of C4 plants. Based on stable oxygen isotope values from the lake sediments and calcretes, this study suggests that the global warming trend that followed the Late Miocene continued into the Pliocene within the CVP.