Using fractal and multifractal methods to reveal geophysical anomalies in Sardouyeh District, Kerman, Iran

In recent decades, airborne geophysical technologies have gained popularity in mineral prospecting, especially at regional scales with limited rock outcrops and intricate geological conditions dominating the region, that impose errors to the obtained results. To address this, incorporation of fractal/multifractal methodologies into geophysical data will result in more certain outcomes. In this research, content-area (C-A), multifractal inverse distance weighting (MIDW) and singularity index (SI) methods were applied on airborne magnetometric and radiometric data to discover favorable copper mineralization areas in Sardouyeh district, SE Iran. Based on success-rate curves, MIDW and C-A fractal methods had far better performance in highlighting the main anomalies than ordinary IDW. However, they could not separate local anomalies. In contrast, the singularity mapping as a windows-based technique provided more optimal results, which, in addition to the main anomalies, could highlight the weak and local geophysical anomalies dominated by the strong background. Accordingly, the newly revealed anomalies using singularity technique are strongly correlated to the known copper deposits and geological evidences in the region. Moreover, to more accurately determine the geophysical anomalies spatially linked to Cu deposits and generate 2-class (favorable/non-favorable) singularity maps, the normalized density index was implemented. The results demonstrated that alpha values of 1.96 and 1.94 are optimal thresholds for mapping singularity values of magnetometric and radiometric anomalies, respectively. Therefore, the favorable classes derived by normalized density index are suggested to be used for tracing undiscovered Cu deposits in further exploration stages.