The drone-borne magnetic survey as the optimal strategy for high-resolution investigations in presence of extremely rough terrains: The case study of the Taverna San Felice quarry dike

In the Taverna San Felice limestone active quarry (Italy) excavation has progressively exposed a magmatic dike embedded in a calcareous succession. The dike outcrops are scattered among the high vertical steps of the quarry, whereas outside the excavated area the steep mountain slope covered by a dense bush vegetation make direct inspection and geological mapping a challenging task. To map the areal extension of the dike and to define its direction and its relationship with tectonic lines over an area larger than the quarry, a magnetic survey was performed. Given the above-mentioned extremely rugged terrain, a UAV-based magnetic survey was the preferred acquisition strategy. Data were acquired by rigidly fixing the magnetometer to the UAV landing sled, using a sensor with a very high-frequency (1000 Hz) acquisition rate. The acquisition strategy and some simple processing steps resulted in a detailed drone-borne total field anomaly map. This dataset allowed for a mapping of the dike outside the quarry area and the identification of a vent fed by the dike. The 2D forward modelling of the magnetic data was constrained by a field estimation of the intensity of the total magnetization and by the depth to the dike's top, in places where it is outcropping.