Estimation of Curie point depth from spectral analysis of aeromagnetic data for preliminary exploration of geothermal resources in central region of Kerman Province

Summary To optimize the widespread use of fossil fuels in Iran, different resources of renewable energy can be considered as promising challenges. The everincreasing energy demands of the country can be satisfied by the very rich resources of renewable energy such as wind, solar, biomass, and geothermal energies. This paper presents the results of Curie point depth calculations from spectral analysis of aeromagnetic data for preliminary exploration of geothermal resources in central region of Kerman Province. The calculations were performed for an area of 22010 km2 located north of Jiroft city and east of Baft city. RTP correction and band pass filtering were first applied to the data. Then, the block dimension of 80×80 km with an overlap of 50% was selected for the spectral analysis. The spectral power was calculated for all the blocks and the Curie depth map was obtained for the study area. The results showed that the shallowest Curie depths are about 9 km observed in the southeastern part of the study area. Different information layers including geological and surface information layers were, then, onvestigated in the ArcMap software. Concentration of several hot springs and presence of faults, intrusive structures, and volcanic rocks prove a high probability of geothermal anomaly in the area of shallowest Curie depth.
Introduction Although there are evidences of rich geothermal potential regions in Iran, very few exploration studies have been carried out so far, especially in the eastern and central regions of the country. Geothermal heat flux is one of the main parameters to be investigated in geothermal exploration programs but few direct heat flux measurements are available in Iran. Given the proved relation between Curie depths and heat flux, we can use magnetic data to calculate the Curie depths in areas where few or no direct heat flow measurements are available. Hojat et al. (2016) used an iterative forward modeling approach to calculate the Curie depth of Kerman province from satellite magnetic data. The obtained Curie map revealed an area with very shallow Curie depth in the southeastern region of Kerman province. Their finding was confirmed by geological evidence for the probability of a geothermal potential zone. In this paper, aeromagnetic data are used to calculate the Curie depth map for an area of 22010 km2 located in the central region of Kerman Province, part of which overlaps with the probable geothermal zone revealed from the previous study.
Methodology and Approaches The aeromagnetic data have first been processed in the Oasis Montaj software. The IGRF model has been used to remove the main field from the observations. RTP and Bandpass filtering have then been applied to the data. The block dimension of 80×80 km with the overlap of 50% has been selected for the spectral analysis method. After calculating the Curie depth map of the study area, different information layers including hot springs, faults, intrusive bodies, and volcanic structures have been combined in the ArcMap software to validate the interpretation of the results.
Results and Conclusions 1. Curie depth values were obtained in the range of 9-9.9 km. 2. The shallowest Curie depths occurred in the southeastern part of the study area. 3. The main concentration of hot springs, intrusive bodies, and volcanic structures was in the area with the shallowest Curie depths. 4. It is suggested to perform detailed land surveys in the most probable area detected in this study.