Gravity and magnetic exploration applied to iron ore deposits in the Sierra Grande area, Río Negro Province, Argentina

The Ordovician-Devonian Sierra Grande Formation, Rio Negro Province, Argentina contains three quarzitic members with two iron horizons. Its South Deposit includes both iron horizons. However, the East Deposit is relatively unknown, lacking information about geometry, depth and reserves. To answer these questions, we apply geophysical methods for the rapid evaluation of the East Deposit, using gravity and magnetic measures. The processing of these data allows the suggestion of two 2D models for calculating thicknesses, angles and depth of the iron horizons. The adjustments between the calculated and the observed curve are less than 6%. One model proposes the existence of the Alfaro iron horizon, and the other one proposes the presence of the Rosales iron horizon at depth. The Bouguer anomaly gravimetric maps allow us to calculate the mineral mass, resulting in 125 million iron tons. Thus, this study allowed us to calculate the thicknesses, angles and depth of both iron horizons, and to adjust and evaluate the mineral reserves with the maximum reliability that potential methods allow when applied to mineral prospecting. These results provide new and valuable information for future mining prospects.