COMPOSITION AND GENESIS OF THE NICKEL-CHROME-BEARING NONTRONITE AND MONTMORILLONITE IN LATERITIZED ULTRAMAFIC ROCKS IN THE MURATDAĞI REGION (UŞAK, WESTERN ANATOLIA), TURKEY

摘要: Widespread lateritized ultramafic rocks in the southern part of Muratdagi region Turkey constitute a significant source Ni-Cr-bearing ore with economic potential. However, no mineralogical or geochemical characterizations these important materials have been performed previously. The aim present study was to describe mineralogy, geochemistry, and genesis smectite garnierite ferruginous saprolite associated ophiolite-related rocks. lateritic zones are well developed over serpentinized harzburgitic mantle peridotites. units related bedrocks were examined using polarized-light microscopy, X-ray diffraction, scanning transmission electron microscopies, chemical isotopic methods. garnierite-containing saprolites enriched smectite, Fe-(oxyhydr)oxide phases, opal-CT. Micromorphological images revealed that flaky and, locally, Fe-rich particles, alunite, gypsum, gibbsite, sulfur crystals along fractures dissolution voids. development demonstrates weathering. presence silicified phases local native vertical and/or subvertical fault infillings indicative hydrothermal processes extensional, tectonically systems. Chemical weathering processes, which probably started during Oligocene Miocene, led formation nontronite, Fe-bearing montmorillonite, kaolinite. Nickel Cr concentrated significantly zone positively correlated Fe2O3 content, is controlled by phases. Nickel-Cr-bearing nontronite montmorillonite precipitated from alkaline water as result increasing (Fe2O3+Al2O3+Cr2O5+Ni+Co)/(MgO+SiO2) ratio under control both processes. Fe Mg (associated Ni Cr) required for supplied solutions alteration olivine pyroxene bedrock; Al schists, granite, volcanic units.