The effect of Tous fault on groundwater resources in northern parts of Mashhad plain

Mashhad Plain affects by a series of active faults in the northern margin of the Binalud and the southern margin of the Kopet-Dagh mountain ranges. The activity of these faults forms the morphology of the stepped bedrock of the Plain. In addition, the faults’ activities in the Quaternary period are the main effective parameters in thickness and texture of aquifer deposits in Mashhad Plain. In this regard, one of the active and important faults in Mashhad Plain is Tous fault, which runs from the northwest of Mashhad Plain into the city of Mashhad. The present research aims to analyze the effect of this fault on groundwater resources in the north of Mashhad Plain. For this purpose, ancient geoelectric studies and many well logs data are gathered, interpreted and by the combination of all of the geology information a new model for groundwater resource of the area proposed. The results of this study indicate that activities of Tous fault results to the uplifting of the Neogene Marly bedrock of Mashhad Plain, which such as a barrier prevents the flow of groundwater from the northern plain to the main aquifer of Mashhad Plain, and practically has divided the alluvial aquifer of Mashhad Plain into two parts. The maximum sediment thickness can be seen adjacent to the fault in the north of the Tous region and the tomb of Ferdowsi.