Application of magnetic and gravity methods to the exploration of sodium sulfate deposits, case study: Garmab mine, Semnan, Iran

Abstract

This study investigates the feasibility of using potential field (magnetic and gravity) data for geophysical exploration of sodium sulfate (salt-cake) resources; more specifically glauberite (sodium sulfate) and Eugsterite (sodium calcium sulfate) are two prevalent minerals of the Garmab mine in Semnan province, Iran.The geophysical data were collected on several profiles perpendicular to geological structures of the area and the residual magnetic and gravity maps were generated. Based on the magnetic susceptibility and density measurements of ore and waste samples, the areas identified by low magnetic and high gravity anomalies were associated with high potential zones for glauberite mineralization.Three-dimensional inversion of potential field data was applied to the residual data, leading to a petrophysical model of the magnetic susceptibility and density contrast of sought salt rocks. We found that the ore bodies could be successfully characterized by low-susceptibility and high-density. In this paper, the susceptibility and density models from inversion are consistent with the geological and drilling data. Results of the integrated application of magnetic and gravity data can be used to delineate sodium sulfate prospects as well.