Efficacy of magnetic susceptibility technique to estimate metal concentration in some igneous rocks

Abstract

The present study was conducted to explore the relationships between magnetic measures and some heavy metals in some igneous rocks in north-western Iran. For this purpose, four major rocks including ultrabasic, basalt, granite and andesite were selected and totally 60 samples were collected. The collected samples were analyzed for magnetic measurements (\( \chi_{\text{lf}} \), \( \chi_{\text{hf}} \), \( \chi_{\text{fd}} \)) and heavy metals concentration (Fe, Cr, Cu, Zn, Co, Mn and Ni) by atomic absorption spectroscopy. Some samples were analyzed by XRD for iron mineral characterization. The results indicated that the highest and lowest \( \chi_{\text{lf}} \) and all measured heavy metals were found in ultrabasic (as a basic rock) and in granite (as an acidic rock), respectively. X-ray analysis confirmed the higher presence of magnetite/maghemite in basic rocks. Positive and significant correlations were found between magnetic susceptibility at low frequency and all heavy metals’ concentration except for Ni. Overall, magnetic susceptibility serves as a preliminary assessment of rock samples, providing rapid, non-destructive, economical and easy information about heavy metal concentration in igneous rocks in the study area.