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

Abstract

Oligocene aged evaporite formations are observed in shallow sea-sabkha environments that developin highly restricted conditions from sea in northeastern of the Muş basin. Evaporites are observed asalternated and intercalated with clastics and carbonates that developed under the control of factorssuch as climate, tectonism, volcanism and diagenesis. Evaporites consist of primary and secondarygypsum and minor anhydrite. In petrographic and minerologic examinations, secondary gypsumtextures such as alabastrin, porphyroblastic and satin spar with anhydrite relicts, late diageneticcalcite, 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 aresult of all these studies, the conditions and phases of the evaporites from the sedimentation stageto early diagenesis and late diagenesis processes of the evaporites were illuminated. Secondarygypsum consists of the origin of primary anhydrite and gypsum. From the diagenetic fluids releasedduring the gypsum-anhydrite transformation, the late diagenetic calcite and by the interaction ofthe ions carried by the hydrothermal solutions to the basin with the groundwater were formed thecelestite. Stream activity in the basin was determined by the presence of detritic minerals in gypsumminerals.