Hydrothermal Alteration Mapping in Northern Khur, Iran, Using ASTER Image Processing: a New Insight to the Type of Copper Mineralization

摘要

Eastern Iran has great potential for the discovery of different types of mineralization. The study area encompasses Tertiary magmatism in the northern Lut block located in northern Khur, South Khorasan, eastern Iran and is mostly covered by volcanic rocks, which are intruded by porphyritic subvolcanic intrusions in some places. Application of the spectral angle mapper (SAM) technique to Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) images detected sericitic, argillic, and propylitic alterations, silicification, and secondary iron oxides. The alteration is linear and associated within vein-type mineralization. Twelve prospective areas are selected for detailed exploration and based on our processing results, in addition to NW-SE faults, which are associated with Cu mineralization indications, NE-SW faults are also shown to be important. Based on the presence of subvolcanic rocks and numerous Cu ± Pb-Zn vein-type mineralizations, extensive alteration, high anomaly of Cu and Zn (up to 100 ppm), the age (43.6 to 31.4 Ma) and the initial 87Sr/86Sr ratio (0.7047 to 0.7065) of the igneous rocks, and the metallogenic epoch of the Lut block (middle Eocene-lower Oligocene) for the formation of porphyry Cu and epithermal deposits, the studied area shows great potential for porphyry copper deposits.