Investigation of mineralogical and geochemical characteristics of the tertiary sedimentary units around Bala (Ankara)

This study deals with the mineralogical and geochemical properties of the Ter-tiary sedimentary units around Bala district, Aşıkoğlu village located in so-uthwest of Ankara, in Kırşehir İ30-d3, İ30-d4 sheets. For this purpose, all the sedimentary units collected from the drilling core that ensured from Madinsan A.Ş. who realize the operations activities for the evaporitic rocks especially gypsum have been detected litologically. X-RD and mineralogical analyses of the 118 samples collected from the drilling cores have been conducted. These analyses determine the whole rock and clay mineral compositions of the samp-les as well as the vertical and lateral distributions of the minerals. The analyses show that gypsum, clay, quartz are dominant minerals in the study area. In ad-dition to these minerals, the analyses have detected the existence of calcite, anhydrite and small amount of feldspar minerals in some sample. Clay fraction analyses indicate that smectite and kaolinites are the dominant clay minerals for this region and illite and klorite could be observed in some samples. Chemical analyses of 85 samples have been performed. The results of chemi-cal analyses state that gypsum and calcite samples are precipitated in sabkha environment that were influenced by mixing of marine and non-marine brines. The occurence of variable Sr concentrations indicates that the hydrological conditions are in a state of flux and reveals unstability of salinity of the envi-ronment. As a consequence, this reveals that evaporation/precipitation ratio changed periodic intervals.