Geophysical Investigation of Magnetometry in Zarnan-Chorenab Zanjan Menitite Iron Deposit

Zarnan-Chorehnab iron deposits are located at 5 km northeast of Zanjan city in the Tarom mountains, between Zarnan and Chorehnab villages. Mineralogical studies, as well as field observations show that iron mineralization is mostly magnetite type. However, hematite and goethite minerals are also formed to a lesser extent due to weathering and alteration. Iron ores in this area are formed as veins and lenses within Oligocene intrusive bodies. Inside the volcanic rocks, mineralization is also observed in the form of veins with small dimensions. The thickness of the veins can be traced between 0.5 to about 15 meters and their length up to about 200 meters. Iron deposits are one of the main stages of their exploration due to the presence of magnetite minerals with high magnetic properties and hematite with low magnetic properties. For this purpose, geophysical surveys were carried out by magnetometric method in 5240 stations in an area of 8 km2 to determine the potential areas of iron mineralization and to investigate the depth of mineralization. In this research, total magnetic maps, pole reversal, analytical signal, and upward continuation were prepared. The results obtained from the drilling finely correspond with the magnetometric survey. Based on the results of these studies, nine anomalies (An1-An9) were identified in the study area, anomalies of An3, An8, and An9 extend to a depth of about 40 m, and other anomalies are supposed to be found to a greater depth. The result of magnetic modeling data determines the position (location and approximate depth) and geometry of the masses causing magnetic anomalies.