Detection of mineralization stages using zonality and multifractal modeling based on geological and geochemical data in the Au-(Cu) intrusion-related Gouzal-Bolagh deposit, NW Iran
Seyed Mehran Heidari, Peyman Afzal, Majid Ghaderi, Behnam Sadeghi
Abstract
The objective of this paper is to detect various gold and copper mineralization stages according to surface lithogeochemical data utilizing zonality index and spectrum-area (S-A) multifractal modeling along with geological data in the Au-(Cu) intrusion-related Gouzal-Bolagh deposit, northwestern Iran. Gold mineralization at Gouzal-Bolagh consists of quartz-sulfide veins within the Paleocene batholithic granitoid complex, which has intruded into the Mesozoic and older metamorphic rocks and shales. Considering the mineralization type, a zonality index was determined as (Au + Cu)/(As + Sb). Au, Cu, and zonality index values were categorized by the S-A multifractal model and the log–log plots. Moreover, multifractal modeling of the zonality index in correlation with geological (specifically mineralographical) data shows that there are three stages for mineralization including Pre-, main and post-mineralization (supergene enrichment). The main stage of mineralization formed from two sub-stages:A (Quartz vein and veinlet sulfidation), B (Quartz sulfide brecciation). In addition, various stages of mineralization contain zonality index values of < 31.8, 31.8–507.3, 507.3–758.3, 758.3–1628.7 and >1628.7 for background, pre-mineralization, sub-stages A, B and supergene, respectively. The background is a granitic batholith containing silicic mineralized veins with a NE-SW trend. Results obtained by this study demonstrate that there are major occurrences of gold and copper mineralization in the sulfidation and brecciation sub-stages, respectively.