Clays and Clay Minerals, Vol. 57, No. 3, 311–329, 2009.
Loading...
Authors
Kadir, Selahattin
Kart, Firdevs
Issue Date
2009
Type
Article
Language
Keywords
Periodicals , Geology , Geochemistry , Granite-granodiorite Complexes , Hydrothermal Alteration , Kaolinite , Mineralogy , Sedimentary Units , Stable Isotopes , Turkey
Alternative Title
The Occurrence And Origin Of The Sogut Kaolinite Deposits In The Paleozoic Saricakaya Granite-granodiorite Complexes And Overlying Neogene Sediments (bilecik, Northwestern Turkey)
Abstract
The Sogut kaolinite deposits at C¸ altı, I˙nhisar, and Kure, Turkey, are an important source of raw materials for the ceramics industry of that country, but no detailed mineralogical or geochemical characterizations of these economically important materials have been carried out to date. The purpose of this study was to fill this gap by performing mineralogical, geochemical, and isotopic characterizations of these kaolinite deposits which occur within Paleozoic granite-granodiorite complexes that are crosscut by aplite and pegmatite dikes, and overlain by Neogene sedimentary units. These units are dominated by quartz veins and networks of subvertical fractures and weak zones that were invaded by hydrothermal fluids, resulting in their kaolinization and silicification. Altered units and related host rocks were examined using polarized-light microscopy, X-ray diffractometry, scanning electron microscopy, infrared spectroscopy, and chemical and isotopic methods. Feldspar crystals are either sericitized or kaolinized, and mica exhibits partial chloritization; Fe-Ti-Mn oxides occur within fractures. Kaolinite crystals occur in authigenic vermiform or plate-like stacked forms, having contacts with resorbed feldspar crystals which locally exhibit thick, platy, and subparallel orientations relative to microfractures, the pathways for hydrothermal-fluid injection. Altered feldspar relicts are associated mainly with kaolinite, smectite, quartz crystals, and illite/mica. Increase in (Al+Fe)/Si in the kaolinized units (relative to host-rock granite and granodiorite complexes and silicification), depletion of Ba+Rb, and a negative Eu anomaly reveal that the alteration of feldspar by hydrothermal fluid, the character of which was determined from O- and H-isotopic values, resulted in the precipitation of kaolinite. Thus, the So¨g˘u¨ t kaolinite deposit possibly formed by hydrothermal alteration and a feldspar dissolution-precipitation mechanism in both the granitegranodiorites complexes and related overlying sedimentary units under acidic environmental conditions, which developed via depletion of the soluble elements Na and Ca.
Description
gsccm57304-kad.pdf -- 1.68MB
Citation
Clays and Clay Minerals, Vol. 57, No. 3, 311–329, 2009.
Publisher
License
Copyright © 2006-2018