Large-magnitude Ring structures as structural precursors for porphyry Cu deposit formation in Kerman copper belt, Iran

Structural analysis of remotely sensed data provides a method of assessing the structural significance of Large-magnitude regional metallogenesis in the Kerman porphyry Cu belt in the southern part of the central Iranian volcanic belt. The role of large-magnitude ring structures in the distribution of hydrothermal alteration zones and porphyry copper deposits in the southern part of the Kerman porphyry copper belt SE Iran is discussed. Ring structures are large circular or elliptical shaped features which are partly recognized on satellite images. In this study, Landsat multispectral images were used to identify the rings and also associated hydrothermal alteration zones. The rudimentary identification stages of the circles were mainly based on their circular characteristics on the images. The present research, utilizes various Landsat Enhanced Thematic Mapper Plus (ETM⁺) image-processing techniques, including false color composite images, color composite ratio images, band ratio, and standard principal component (PC) image analysis on six bands and color composite selective PC images in addition to structural analysis, regionally, to discriminate the hydrothermal alteration zones and investigate the distribution of the alteration zones associated with Cu mineralization mostly encompassed within the large ring structures. The associated mineralization in the study area are mainly of porphyry Cu and vein type base metal sulfide deposits. There is a clear structural relationship between the large circles, mineralization and also hydrothermal alteration zones. These circles have encompassed almost entirely of the Cu deposits and prospects in the southern part of the Kerman porphyry copper belt. Formation of the large circular structures do not appear to be related to the external processes but traces of a, geophysically, positive residual anomaly are recognizable on the complete Bouguer anomaly map of the region in which an updoming of the upper mantle is observed. This study contributes to our knowledge for copper exploration in this region, along with, recognizing same large magnitude structural features (ring structures) in regional distribution of hydrothermal alteration zones.