Application of the fractal method to determine the membership function parameter for geoelectrical data (case study: Hamyj copper deposit, Iran)

Near Surface Geophysics

2019

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The main issue in mineral exploration is to obtain as much information as possible in a time‐ and cost‐efficient manner. This may be achieved through a combination of geophysical methods including the induced polarization method. The induced polarization is the most applicable method in case of metal exploration through drilling. We argue that the relationship between induced polarization, electrical resistivity and ore grade data may be used in resource estimation. This argument is tested in the active copper mine of Madan Bozorg, Abassabad, which is located in the Miami‐Sabzevar mineralization belt in NW Iran. Within the borehole locations, geophysical profiles of induced polarization and electrical resistivity were designed and surveyed using combined resistivity sounding and profiling array. Two‐dimensional models of induced polarization and electrical resistivity were prepared through inversion of geophysical data, after the primary processing. The three‐dimensional block models of induced polarization and electrical resistivity were also compiled using geostatistical methods. Obtained two‐dimensional and three‐dimensional models of induced polarization and electrical resistivity were checked using exploratory boreholes to investigate the relationship among induced polarization, electrical resistivity and copper grade. The three‐dimensional block model of the copper ore was prepared using cokriging and artificial neural network, using a combination of induced polarization and drilling data. In the cases where borehole data were unavailable, the presence of copper ore was predicted by artificial neural network and cokriging methods, and the three‐dimensional models of ore body were constructed in all of the study area. Obtained models based on the predicted copper ore distribution were checked and compared with ore distribution model compiled using drilling data. The results indicate a good agreement between predicted and real results. This led to reduction of borehole number to about 45% and the optimization of boreholes locations. Finally, an optimized drilling plan has been prepared and presented for the Abassabad copper mine.

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Section: Resultsmentioning

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Section: Introductionmentioning

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Investigating the applicability of induced polarization method in ore modelling and drilling optimization: a case study from Abassabad, Iran

Near Surface Geophysics

2019

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“…Anomaly values were defined based on the fractal methods. Due to the data, the "concentration-area" method (Ferdows and Ramazi, 2015) has been used in this research for separation of the anomalous value from the background. The obtained threshold correlated with drilling results and the obtained threshold was modified.…”

Section: Inversion Resultsmentioning

confidence: 99%

Mineral resource estimation using a combination of drilling and IP&Rs data using statistical and cokriging methods

Bulletin of the Mineral Research and Exploration

2018

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The aim of this research is the mineral resource estimation using a combination of drilling and IP-Rs data. Therefore the approach of this paper is to study the correlation of induced polarization (IP) and Electrical resistivity (Rs) data with drilling data in order to grade estimation and mineral resource estimation. Reducing the boreholes number and optimization of the boreholes location is another aim of this research. The Abassabad copper mine located in Miami-Sabzevar mineralization belt northeast Iran was chosen as a case study. Within the borehole locations, geophysical profiles were designed and surveyed. After IP-Rs data inversion, 2D sections were prepared. The 3D block models of IP-Rs were constructed by geostatistical methods. The correlation between IP-Rs and drilling data were examined by statistical and geostatistical methods using regression, multivariate regression analysis, and cokriging. Based on the mentioned methods copper grade was estimated and the 3D block models of Cu grade were constructed. Obtained models were checked and compared with real Cu model compiled according to drilling data which was done after geophysical measurements. Results showed that the regression between IP data and Cu grade was more appropriate with least error. Rs data are not suitable for Cu estimation, due to changing intervals which led to increasing estimation error. Based on the suggestions of this paper, we could reduce the number of boreholes to 30% of the initial number and optimize the boreholes locations.

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Compiling and verifying 3D models of 2D induced polarization and resistivity data by geostatistical methods

2018

Acta Geophys.