MINERALOGICAL, GEOCHEMICAL AND GENETIC IMPLICATION OF SMECTITE AND SEPIOLITE IN THE OLIGO/MIOCENE LACUSTRINE CLAYEY SEDIMENTS OF THE KURTULMUSTEPE FORMATION, AKTOPRAK BASIN, NIGDE, CENTRAL ANATOLIA, TURKEY
Küçük Resim Yok
Tarih
2013
Yazarlar
Dergi Başlığı
Dergi ISSN
Cilt Başlığı
Yayıncı
STEF92 TECHNOLOGY LTD
Erişim Hakkı
info:eu-repo/semantics/closedAccess
Özet
Aktoprak Basin is situated among the Melendiz Mountains in the north, middle Taurus range in the south, Tuz Golu and Konya plain in the west and Nigde Crystalline Massif in the east. The Oligo/Miocene Kurtulmustepe Formation represents fluvial and shallow lake sediments of the Aktoprak Basin. This unit consists of thin bedded white marl, alternating with massif of white limestone, and red colored mudstone overlies Zeyvegedigi anhidriti, south of Ulukisla/Nigde. Further south in the area between Aktoprak and Yeniyildiz villages, this formation overlies ophiolitic basement rocks (Late Cretaceous) and this area consists of marl, limestone, and sandstone and mudstone alternation. These units were examined using polarised-light microscopy, X-ray diffractometry, scanning electron microscopy and energy dispersive analyses (SEM-EDX), and chemical analyses. Mineralogical distribution in these units south to north is as follow: (1) Quartz + calcite + feldspar and amphibole; relative abundance of clay minerals are, smectite + sepiolite (2) Calcite + feldspar + quartz and amphibole; relative abundance of clay minerals are, smectite + sepiolite While smectite is abundant clay mineral in southern part of the basin, sepiolite amount relatively increases to the northward in mudstone deposits of the Kurtulmustepe Formation. Marl units exhibit micritic texture, sepiolite dominated by microsparitic calcite crystals in desiccation cracks and pores, also bear vadose cements and organic matter (a rich assemblage of gastropods, ostracodes, plant spoors and algae and bivalve's fragments). Observations via scanning electron microscopy indicate formation of sepiolite as bridges between calcite crystal, edging smectite plates and fiber-bundle. Marl samples are characterized by high CaO and loss on ignition values, and host-rock mudstone samples consist mainly of SiO2, Al2O3+Fe2O3+MgO, LOI and relatively high CaO value, revealing the presence of smectite and sepiolite associated with feldspar, quartz and calcite. Barium and Rb are relatively high and constant in the mudstone, compared to the marl. Positive correlation between 1(20 and Rb+Ba in mudstone and marl samples as a function of the presence of K-bearing minerals, such as feldspar. Based on field evidence, mineralogical and geochemical determinations, the sepiolite is presumed to have formed authigenically either by coprecipate with calcite during calcification or by conversion from detrital smectite or direct precipitation under super saturation condition. Thus, sepiolite precipitated in a vadose zone from strongly evaporatived alkaline water rich in Si and Mg and low in Al at increased temperatures and advanced stage of marl formation. The Si, Mg, Al+Fe and Ca required for sepiolite formation and calcification were supplied in solution from the smectitic clays, ophiolitic units and related volcanic units and carbonates in the close area.
Açıklama
13th International Multidisciplinary Scientific Geoconference, SGEM 2013 -- JUN 16-22, 2013 -- Albena, BULGARIA
Anahtar Kelimeler
Marl and Mudstone, Sepiolite and Smectite, Oligo/Miocene
Kaynak
GEOCONFERENCE ON SCIENCE AND TECHNOLOGIES IN GEOLOGY, EXPLORATION AND MINING, SGEM 2013, VOL I
WoS Q Değeri
N/A
