Yazar "Ozcan, Selcuk" seçeneğine göre listele

Listeleniyor 1 - 3 / 3
  • Küçük Resim Yok
    Öğe
    Paleosol and dolocrete associated clay mineral occurrences in siliciclastic red sediments of the Late Miocene Komisini Formation of the Tuzgolu basin in central Turkey
    (ELSEVIER SCIENCE BV, 2016) Gurel, Ali; Ozcan, Selcuk
    The Late Miocene was characterized by high global temperatures and partly to nearly complete desiccation of the Mediterranean Sea throughout the latter part of the Messinian age (the Messinian salinity crisis). The Late Miocene marine Mediterranean Sea area has been widely studied from different perspectives, but terrestrial paleoenvironmental and paleoclimatic records from the Mediterranean area are highly limited in their spatial range. To this end, the paleosols, dolocrete and fluvial sedimentary rocks of the Komisini Formation in the northwestern part of the Tuzgolu basin are described in detail. Six lithofacies were identified as (A) clast-supported gravel, (B) massive (pebbly) sandstone, (C) massive mudstone, (D) disrupted mud, (E) disrupted conglomerate, and (F) disrupted matrix-supported conglomerate. The siliciclastic facies were interpreted as braidplain, and the distal part of braidplain deposits is associated with an ophiolitic area while the disrupted mud and disrupted conglomerate were identified as three types of paleosols: Inceptisols, Aridisol and Vertisols. The calcretes occur in the paleosols in nodular, powder, and massive forms. Clay minerals include smectite, chlorite, palygorsldte, illite, and serpentine. Gypsum, smectite and chlorite are dominant minerals at the base and middle part of the section, whereas palygorskite and illite appear as the prevailing clay minerals in the upper sections. Smectite, illite and palygorskite precipitated in a vadose zone from strongly evaporated alkaline water rich in Si, Ca and Mg and poor in Al at increased temperatures and at an advanced stage of dolocrete and paleosol formation. K, Si, Mg, Al + Fe and Ca are required for smectite, illite, palygorskite and calcification. Given the increase in Ba, Cr, Ni and Co, these cations might have originated from ophiolite, carbonate and volcanic units. As a consequence, the vertical distribution of clay mineral types suggests the variations of paleoclimatic conditions during the deposition, and the relationships among the type of host rock, paleosol and dolocrete, which corresponds to nearly complete desiccation of the Mediterranean Sea. (C) 2016 Elsevier B.V. All rights reserved.
  • Küçük Resim Yok
    Öğe
    Sedimentology and mineralogy of late miocene Paleosols and calcrete rich sediments in the western part of central anotolian volcanic province (CAVP), Turkey
    (2008) Guel, Ali; Kerey, Ilyas 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 11 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 arid to wet conditions.
  • Küçük Resim Yok
    Öğe
    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.