MINERALOGICAL AND GENETIC-RELATIONSHIPS BETWEEN CARBONATE AND SEPIOLITE-PALYGORSKITE FORMATIONS IN THE NEOGENE LACUSTRINE KONYA BASIN, TURKEY

Neogene (Upper Miocene-Pliocene) lacustrine sediments of northern Kony a consist of conglomerate, sandstone, marl mudstone, claystone, clayey limestone, and limestone. Limestones are white, beige-cream colored, fine-grained and contain remnants of plant roots. Brecciation, calcret ion mud cracks, and dissolution voids are common. Claystones are typic al with white and green colors. Green claystone cropping out at the lo wer part of the sequence is alternated with mudstone and sandstone. Wh ite claystone alternating with carbonate units appears at the upper pa rt of the sequence. Carbonate units are found as intercalated layers a nd lenses of conglomerate, sandstone, and mudstone. Calcite, dolomite, feldspar, and quartz minerals are dominant in the study area They are accompanied by sepiolite, palygorskite, smectite, chlorite, and illit e minerals hosted by white colored clayey limestone and claystone. In addition, on the green colored claystones, minerals such as chlorite, smectite, and illite are formed. SEM studies indicate that sepiolite-p alygorskite fiber and fiber bundles cover calcite and dolomite. Calcit e and dolomite are of hexagonal and rhombic crystal types. These miner als show a meniscus type cement which characterizes a vadose zone. Par agenesis and textural features of the minerals determined in the study area indicate that precipitation should occur due to climate fluctuat ions ranging from arid, semi-arid, and wet conditions. Changes in clim atic conditions does affect the lacustrine water chemistry and precipi tation of carbonate and detrital units. Sepiolite and palygorskite for m authigenically as a result of the calcretion of carbonate units in a lkaline conditions, high Si and Mg activity, and low Al.