The trona deposit is restricted to the lower section of the shale unit and trona beds alternate with bituminous shales and claystones. The Neogene units are predominantly deposited in fluvial and playa-lake environments. The possible source of Na required for the formation of the trona deposit is the tuffs and tuffites interbedded with the sediments in the NE of the Beypazari basin. -from Authors