NEW INSIGHTS INTO INTERPRETATION OF AEROMAGNETIC DATA FOR DISTRIBUTION OF IGNEOUS ROCKS IN CENTRAL IRAN

Abstract

New insights in the aeromagnetic data over the Central Iranian Microcontinent (CIM) revealed interesting results for the future studies and exploration. This work presents the interpretation of the different magnetic analysis and calculated 3D inversion model to provide important insights into the distribution of igneous rocks in the area that may be traced under significant cover. By analyzing several hundred magnetic susceptibility data points and aeromagnetic anomalies of known igneous rocks over the area, it was determined that maficultramafic intrusive rocks generally have a high magnetic susceptibility and produce strong magnetic response. Intermediate-felsic intrusive rocks have a low magnetic susceptibility and show a smooth gradient variation and commonly regular shape. Volcanic rocks show a wide range of magnetic susceptibility; therefore, the aeromagnetic anomalies are often random or show strong amplitude with high frequency signals which is eliminated rapidly when an upward continuation is applied. Based on results of analysis of different magnetic map and 3D inversion of data, and combining this information with known outcropped of igneous rocks, we revealed 1215 concealed intrusive rocks and 528 volcanic rocks in the area. We also renewed the boundaries of tens outcropped igneous rocks. The known and new mapped igneous rocks can be identified as 12 regions (or zones) for intrusive rocks and 4 regions for volcanic rocks. The results indicate that the mafic-ultramafic rocks are mainly located in Sistan suture zone of eastern Iran along Nehbandan fault zone. It also shows that the many parts of Lut block as a main portion of CIM has been under magmatic events, so that the most of concealed igneous rocks is distributed in the middle and southern part of Lut block. Volcanic rocks are widely developed in southeastern and northern parts of the area such as Urumieh-Dokhtar Magmatic Arc, North Lut and Bam region.