MINERALOGY, GEOCHEMISTRY AND GENESIS OF YENIDOGAN (SIVRIHISAR, TURKEY) SEPIOLITE AND RELATED MG-RICH MINERALS

摘要

Several layered sepiolite deposits occur in the Eskisehir Neogene lacustrine basin. The present occurrence found in the SE Eskisehir (Sivrihisar) is the largest layered sepiolite deposit known up to date. This occurrence was investigated in detail along several cross-cuts and consequently by means of XRD, SEM and chemical analysis. Sepiolite and related Mg-rich minerals occur in a ～80 m thick sequence of Lower Pliocene where alternating dolomite and dolomitic marl beds are represented as the principal rock assemblages. The lower half of this section begins with a nearly 2 m thick dolomite-magnesite layer and continues upwards in order: two separate strata with sepiolite, magnesite-bearing dolomite containing both saponite and sepiolite, sepiolite-bearing marl, and sepiolite-bearing saponite beds.