Petrographic- mineralogical examination and diagenetic history of the Paleogene evaporites in Bulanık (Muş), Turkey.

Oligocene aged evaporite formations are observed in shallow sea-sabkha environments that develop in highly restricted conditions from sea in northeastern of the Muş basin. Evaporites are observed as alternated and intercalated with clastics and carbonates that developed under the control of factors such as climate, tectonism, volcanism and diagenesis. Evaporites consist of primary and secondary gypsum and minor anhydrite. In petrographic and minerologic examinations, secondary gypsum textures such as alabastrin, porphyroblastic and satin spar with anhydrite relicts, late diagenetic calcite, bitumen and bioturbation traces were detected. In SEM-EDS studies; celestine crstals, autogenic and detritic clay and quartz grains and euhedral dolomite mineral were observed. As a result of all these studies, the conditions and phases of the evaporites from the sedimentation stage to early diagenesis and late diagenesis processes of the evaporites were illuminated. Secondary gypsum consists of the origin of primary anhydrite and gypsum. From the diagenetic fluids released during the gypsum-anhydrite transformation, the late diagenetic calcite and by the interaction of the ions carried by the hydrothermal solutions to the basin with the groundwater were formed the celestite. Stream activity in the basin was determined by the presence of detritic minerals in gypsum minerals. [ABSTRACT FROM AUTHOR]