Geology, mineralogy, and alteration of the Cu-Pb veins, and their significance in mineral exploration: A case study in the Khajeh-Nezam area, SE Iran

Abstract

Khajeh-Nezam area is situated within the Bam 1:100,000 geological sheet, SE Iran. The area was the subject of silt geochemical studies and consists of highly prospective Cu, Pb, Ba, and Fe veins and veinlets that demonstrate a northwest-southeast trend. A total of 149 silt samples were collected from the area and analyzed for 7 elements (As, Cu, Mo, Pb, Zn, Sb, Ba) using Inductively Coupled Plasma-Optical Emission Spectrometry. Univariate-multivariate statistical analysis the majority of variables demonstrate a distribution that is slightly too moderately positively skewed, which can be accurately explained using a log-normal model. Only Cu, Zn, and Pb demonstrate a normal distribution. The number-size (N-S) fractal model show that. The variables can be classified into two main groups. The first group comprises the main ore-forming elements, namely Cu, Ba, As, and Sb, which are associated with the epithermal system. On the other hand, Mo, Pb, and Zn demonstrate a stronger affiliation with vein and veinlet mineralization that could be linked to the margin of a possible hidden porphyry system. The geochemical halo in the southwestern part of the study area, which overlaps with volcanic rocks, has experienced significant alterations attributed to local intrusions, leading to a level of modification. A secondary weak anomaly, of relatively lesser significance, is observed in Pb, Zn, and Mo. Although these elements are not the primary constituents of the ore, they serve as pathfinder elements in marginal copper porphyry. The results obtained from the study have been utilized to identify concealed ore bodies using the classes defined by N-S classification model. Fieldwork conducted in the area confirms the presence of Fe oxide veins and veinlets that contain copper mineralization, along with carbonate Pb and Cu minerals. Various types of alteration have been identified, including argillic alteration accompanied by quartz and hematite in the vicinity of the veins and veinlets. The findings serve as probable evidence for the existence of a new copper porphyry system in the study area.