ZTEM airborne AFMAG survey results over low sulphidation epithermal gold-silver vein systems at Gold Springs, south eastern Nevada

Abstract

A ZTEM (Z-Tipper Axis Electromagnetic) helicopter AFMAG test survey was conducted in April, 2011, over the Gold Springs Project, in south eastern Nevada, for low sulphide epithermal gold exploration. Previous ground CSAMT surveys at Gold Springs revealed a positive correlation between the known epithermal gold systems and buried, subvertically-dipping resistivity high features that extend to depth. Synthetic forward modeling showed that ZTEM could also be successful, provided topographic effects were accounted for. The ZTEM test results performed over the known epithermal gold prospect in southeastern Nevada appear to correlate very well with the CSAMT results and the known geology, in particular the presence of all the known epithermal centers over resistivity highs. Similar anomalies have been identified in previously unexplored areas of thicker overburden cover. 2D inversions of the airborne ZTEM, using a newly developed Avert2d code that accounts for bird clearance and 2d topography, appear to agree very well with the inversions obtained from ground CSAMT. These results provide encouragement for the application of ZTEM for epithermal gold deposits elsewhere in the district.