ُTN745 : Kurdistan shear zone gold exploration in the Kervian area by modeling and interpretation of induced polarization and resistivity data
Thesis > Central Library of Shahrood University > Mining, Petroleum & Geophysics Engineering > MSc > 2017
Authors:
Saeed Najafi Ghoshebolagh [Author], Ali Reza Arab-Amiri[Supervisor], Abolghasem Kamkar Rouhani[Supervisor], [Advisor]
Abstarct: The economic grade of gold, depending on the different conditions and the type of deposit, is usually just a few ppm. For this, the direct discovery of gold by geophysical methods is very difficult as its amount compared to other associated minerals is small. Therefore, the only way for gold geophysical exploration is indirectly through the identification of the sulfides as its paragenesis. The main methods of geophysical studies for mextallic sulfide deposits is to use electrical resistivity and induced polarization (IP) methods. The study area in this research is Kervian area that is located in the northwestern part of Sanandaj-Sirjan Zone and in southwest of Saqez. In general, the deposits in the area can be divided into two major sedimentary and igneous parts, all of which have been transformed into green schist facies. Mineralization occurs in a sulfide-altered unit, which is silicified and weathered, and contains high sulfide minerals and a hematite-limonite color. Considering the mineralization evidence in the Kervian area, IP and electrical resistivity data in the area were acquired along three survey lines using the dipole-dipole array with an electrode spacing of 30 meters. On these survey lines, EM data in the frequency domain were also acquired by the EM34 system. In order to model and interpret the raw IP and electrical resistivity field data, RES2DINV and ZONDRES2D software packages were used by applying two-dimensional (2D) smooth inverse modeling. EM data modeling was carried out using EM34-2D software. By integrating the results of inverse modeling of IP and electrical resistivity data with the results of geological studies, the main locations of mineralization in the area were identified. For spatial visualization of subsurface gold mineralization, the results of 2D inverse modeling of IP and electrical resistivity data were displayed in three dimensions using RockWorks software. Considering the obtained results, seven points were proposed for drilling. It should be noted that the proposed points are associated with high IP values, which can be due to the presence of mextallic materials such as pyrite accompanied with gold. Therefore, gold mineralization may not be visible or found in some of the proposed points. Borehole data is also used to validate the obtained geophysical anomalies. IP anomalies, which extend in the lithological units of phyllites and carbonates of the area, contain relatively high amounts of gold (higher than 1 ppm) according to the data from drilled boreholes in the area. However, the IP anomalies, located in the altered mylonites, are not associated with gold cut-off grade. Therefore, the obtained geophysical anomalies in the phyllites and carbonates are considered as the main anomalies that are set as the first priority for performing next exploration work. The anomalies, located in the altered mylonites, considering their low grade of gold, possess low economic value and are set as the second exploration priority.
Keywords:
#Induced polarization (IP) #Electrical resistivity #Electromagnetic (EM) #Kervian #Dipole-dipole array #Gold mineralization Link
Keeping place: Central Library of Shahrood University
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