زمین شناسی، کانی سازی، ژئوشیمی و مطالعات مغناطیس سنجی در کانی سازی آهن منطقه کلاته شاهین، استان خراسان رضوی

Abstract

Iron mineralization of Kalate Shahin is located 107 km on the Ghoochan-Neyshaboor road (in Khorasan Razavi province). Subvolcanic intrusive bodies of quartz monzonite to monzonite porphyry intruded the Cretacous limestone. Sedimentary units of the area in decreasing age include Cretaceous limestone and Eocene and Paleocene-Quaternary microconglomerate to sandstone. Mineralization in the region formed in two stages, hypogene and supergene. Pyrite, magnetite and specularite formed in the hypogene and goethite and hematite in the later. Investigation of ƒO2 and temperature conditions indicated that temperature of hydrothermal minerals in the east of the area was less than 350oC. The amount of goethite and hematite in the west of the area is much less than the east and is frequently present as vein and veinlet associated with hydrothermal dolomite. The source of mineralization, hydrothermal solution in west of the area had lower sulfide and temperature but was more oxidized than the east. The result of geochemical analysis using AAS method for Fe, Mn, Mg and Ca elements indicated the highest amount of iron (30.4%) at the trench on the east of the area. Iron showed positive correlation with Mg at this location. There is also relation between the amount of these elements and the distance from the intrusive bodies. Therefore, the intrusive bodies of the area had no role in the mineralization. Total magnetic intensity (TMI) was measured at 742 stations on 2 grid of 20×5 meter. Map of TMI colour image along with contour, Reduction To the Pole (RTP) and upward continued were prepared using ER Mapper. Inspection of magnetic maps indicated distributed anomalies in the area, maybe related to the covered hornblend diorite porphyry which outcrops at about 40 meter apart. Due to the presence of hematite in limestone that correlates with anomalies B and C,magnetite mineralization at depth also may be the causative source of these magnetic anomalies. Therefore, drilling exploration at location of anomalies B and C is proposed.