• Tunnel and Underground Space
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• v.20 no.5
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• pp.390-398
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• 2010

The time-dependent behaviour of rock is very important characteristics which can be utilized as basic input data for underground mine design or in predicting a long-term stability of underground rock mass structures. In this study, creep tests under uniaxial compression were carried out for the granite specimens sampled in Gagok Mine. Burgers model, Griggs and Singh creep laws were used to simulate the measured creep strain. Through comparing the measured creep behaviour with the approximated creep behaviors from Burgers model, Griggs and Singh creep laws, it is shown that Griggs creep law results in the best approximation of granite in Gagok Mine.

• Journal of the Korean earth science society
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• v.35 no.6
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• pp.412-421
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• 2014

In order to develop an effective mineral exploration technique, this study was carried out about the potential mapping of Gagok mine. The deposit model of Gagok mine is widely known. Based on the deposit model, we constructed mining indicator indices using related igneous rocks, faults, and carbonate rocks. By analyzing the spatial correlation between ore and indicator index structures, we decided the weighting values of indices according to the distance from the index structure. The 3D potential mapping was performed using 3D geological model and geological indices. The analyzed potential map verified that the locations and patterns of high potential regions of the results were well matched with those of the known ore bodies. Using the potential mapping results, we could effectively predict the location of a high potential area that has similar geological settings with ore.

• Geophysics and Geophysical Exploration
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• v.17 no.4
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• pp.247-252
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• 2014

Gagok Mine, which is skarn deposits, includes sulfide minerals such as sphalerite, galena, chalcopyrite, and pyrrhotite. To explore these minerals, spectral induced polarization (SIP) is relatively effective compared to other geophysical exploration methods because there is a strong IP effect caused by electrode polarization. In the SIP, the chargeability related to sulfide mineral contents and the time constant related to the grain size of the minerals are obtained. For this reason, we aim to compare difference in the mineralized characteristics between two orebodies in the Gagok Mine by using the chargeability and the time constant. For this study, we sampled ores from the south of Wolgok orebody and the north of Sungok orebody. In order to recognize the mineralization characteristics, the metal content of the samples was measured by a potable XRF and the SIP data of the samples were acquired by using a laboratory SIP measurement system. As a result, the metals in the samples such as Pb, Zn, Cu, and Fe were detected by the portable XRF measurement. In particular, the Fe and Zn contents were far higher than the other metals. The Fe and the Zn were caused by the sphalerite and the pyrrhotite through microscopy. The Wolgok orebody had higher sulfide mineral contents than the Sungok orebody and the result corresponded with the chargeability result. However, we considered that the Sungok orebody had a larger sulfide mineral grain size than the Wolgok orebody because the time constant of the Sungok orebody was larger.

• Geophysics and Geophysical Exploration
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• v.16 no.3
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• pp.180-189
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• 2013

Geophysical exploration is widely used to develop strategic mineral resources in the world because of its efficient method in detecting mineralized zones in the metallic ore deposit. It is important to understand the physical properties of the stratum so that geophysical data can be more accurately interpreted. This paper is to comprehend physical properties of the rock at the Gagok mine, a typical skarn deposit in Korea. Thus, laboratory tests were conducted on specimens of ore and host rocks which were collected from rock outcrops and drill cores at the Gagok mine. Using the measurement system of rock physical property, we investigated the density, magnetic susceptibility, resistivity, and spectral induced polarization. According to the results, all physical properties of specimens had wide differences depending on contents of ore minerals, which are formed by skarnization. Especially, using the chargeability and time constant from the calculated spectral induced polarization data by the Cole-Cole inversion, we could estimate the volume contents as well as the grain size of the sulfide minerals. Therefore, the spectral induced polarization technique may be considered a useful method when exploring metallic ore deposit with sulfide minerals.

• Tunnel and Underground Space
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• v.21 no.5
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• pp.370-376
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• 2011

To design the drainage system of a mine, it is very important to evaluate the groundwater inflow to the mine workings. In this study, continuous steady state flow through rock mass around mine openings developed in Sungok area of Gagok Mine was analyzed. Saturated only model and Saturated/unsaturated model were used as material models of rock mass. Groundwater quantities flowing into Sungok 160 level which is 1216 m long are computed as 1450 $m^3$/day in case of a saturated model and as 1071 $m^3$/day in case of a saturated/unsaturated model. An effect that hydraulic conductivity has on inflow turned out be greater than precipitation and inflow increased linearly with increase of hydraulic conductivity. It was found that change of hydraulic conductivity ratio and orientation have an impact on the variation of inflow and water table.

• The Journal of Engineering Geology
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• v.20 no.1
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• pp.71-78
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• 2010

The Gagok mine is a contact metasomatic deposit, located at Gagok-myeon, Samcheok city and Cheoram-dong, Taebaek city, Gangwon province. The deposit lies within the limestone of Myobong and Pungchon formations, and exists the contact of intrusive granite porphyry. In order to determine the direction and extension of mineralization in the gallery and around the entrance of the ore deposit, we used the ground magnetic survey, the direct current (dc) resistivity survey using dipole-dipole array, and resistivity tomography survey. The ground magnetic survey did not detect the anomalous zone due to ore deposit, while the dc resistivity survey and resistivity tomography survey were successful in delineating the anomalous zone related to the extension of fault toward $N50^{\circ}W$.

• Tunnel and Underground Space
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• v.21 no.1
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• pp.33-40
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• 2011

This study focuses on having a temperature and water pressure effects on the change of material properties of rocks. Granite and limestone specimens from Gagok Mine were thermally treated with predetermined temperatures of 200, 300, 400, 500, 600 and $700^{\circ}C$ (excepting $700^{\circ}C$ for limestone) to estimate the reduction of material properties of rocks caused by heat. Specific gravity, effective porosity, elastic wave velocity, uniaxial compressive strength, Young's modulus and Poisson's ratio for pre-heated specimens were measured. With increasing temperature, material properties of both rock specimens change sequentially. Significant changes of specific gravity, effective porosity and elastic wave porosity occur above $400^{\circ}C$ for granite and $300^{\circ}C$ for limestone. Changes of uniaxial compressive strength, Young's modulus and Poisson's ratio seem to be similar to those of physical properties. GSI of 500, 600 and $700^{\circ}C$ specimens inferred by using uniaxial compressive strength and Young's modulus of preheated granite specimens is found to be 81, 66 and 58 each. In case of pre-heated limestone specimens of 400, 500 and $600^{\circ}C$, the corresponding GSI is 76, 71 and 65 each. 500, 600 and $700^{\circ}C$ granite specimens and 400, 500 and $600^{\circ}C$ limestone specimens were pressurized to 7.5 MPa and their effective porosity, elastic wave velocity, uniaxial compressive strength and Young's modulus were measured. The average value of material properties (mentioned above) of 500, 600 and $700^{\circ}C$ granite specimens under water pressure compared with material properties of non-pressurized pre-heated specimens exhibits the reduction of 7.6, 11.3 and 14.9%, respectively. In case of 400, 500 and $600^{\circ}C$ limestone specimens under water pressure, the average value of material properties decreases by 8.2, 13.8 and 21.9%, respectively.

• Geophysics and Geophysical Exploration
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• v.19 no.4
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• pp.212-219
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• 2016

The development of more advanced geophysical exploration techniques is necessary because the orebodies as yet discovered are increasingly changing in characteristics from shallow/high-grade to deep/low-grade. In this work, laboratory measurement of physical properties of rock samples and a field survey and interpretation of spectral induced polarization (SIP) have been conducted in a skarn metallic deposit, Gagok mine. The purpose of this study is that the applicability of SIP in the exploration of skarn metallic deposits is verified by the comprehensive interpretation between SIP characteristics of rocks obtained from the laboratory measurements and inverted survey results from the field data. In order to understand the SIP characteristics of each lithology, the data of eighty nine rock samples utilized in the previous studies were revaluated. The field survey was carried out using frequency of 0.25 Hz along a survey line designed for intersecting lithological boundaries and evaluating mineralized zones. The mineralized rocks were more conductive (low-resistivity) and capacitive (high-chargeability or strong-phase) than other rocks. Thus, SIP can be one of the very useful tools for the mineral exploration of the skarn deposits.

• Environmental and Resource Economics Review
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• v.18 no.2
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• pp.345-375
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• 2009

In this paper we examined the impact of mineral resources industry on the national economy and necessity of a mineral resources cycle technology development. For this purpose, the case study on Gagok polymetallic (zinc-lead-copper) mine, which is being re-developed, was carried out to study an anticipated effects of application of the full cycle technology. As a consequences of the study, if we apply the technology to a polymetallic (zinc-lead-cooper) mine, we can expect 55 billion won worth of import-substitution effect. Moreover, if applied to 10 similar mines, we can expect the 10.4% of import-substitution effect of the total imports annually. Also, national competitiveness in value chain of mineral industry will be promoted through the technological advancement in upper stream and the full cycle technology will render a service to the mineral industry to be the country's new growth engine.

• Economic and Environmental Geology
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• v.45 no.4
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• pp.351-363
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• 2012

In order to develop the evaluation techniques for the potential sulfide ore reserves, the relationships between the modal vol.%, grain sizes and textural characteristics of the constituent minerals (e.g., sulfides, oxides and skarn minerals) and the Spectral Induced Polarization (SIP) phase differences are examined for the nine rock cores collected from the Gagok Pb-Zn skarn deposit. The Gagok Pb-Zn skarn deposit occurs mainly along the intrusive contact between the Cretaceous granitic rocks and Cambrian Myobong slate and Pungchon limestone. The nine rock cores have been grouped into three showing distinctive SIP phase differences: the highest (Group I), intermediate (Group II) and lowest (Group III). In relation with the modal vol.% of minerals, Group I is characterized by higher pyrrhotite (25-38 vol.%) and amphibole (40-55 vol.%); Group II by intermediate pyrrhotite (7-13 vol.%) and higher garnet (44-68 vol.%); and lower pyrrhotite (1-7 vol.%) and higher pyroxene (24-66 vol.%) stand for Group III. Furthermore, the grains of all the major constituent minerals become smaller from Group I (<5 mm) through Group II (<2.5 mm) to Group III (<1.6 mm). In particular, the pyrrhotite contents and their grain sizes show logarithmic correlation with the SIP phase differences, Although we present here the results solely from nine samples, the systematic interrelations especially for pyrrhotite indicate the potential ability of SIP measurements as a new mine-evaluation technique for the sulfide ore reservoir.