Abstarct: The study areas is the last part of Poshte-Mole anticline which is located in eest and South east of Mansour-abad and north west of Shiraz. This region is placed on the Asmari formation and Drilled water wells in this region include high turbidity. In order to study the causes of turbidity in these water wells, water samples were collectedin Februray and May 2015. For all samplesthe values of turbidith, TSS, TDS, EC, pH, water color, major ions and heavy mextals using ICP-OES were measured. In addition the sediment collected from water samples have been analysed using XRD. The obtainal results indicate that the geological parameters are the most important reasons for production of turbidity in groundwater in the studied region. Presence of abundant fractures in the Asmari formation with marly limestone units and particularly marly intercalations result in the entrance of fine-textured sediments in to water wells (especially 1,2 and 3) confirm the above mentioned instances. Moreover the obtained results from analysis of sediments, settled down in water samples, using XRD show that these sediments are mostly calcium carbonate and clay verifying the marly and marly limestone units as prevailing unit in Asmari formation.