• Economic and Environmental Geology
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• v.8 no.1
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• pp.25-56
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• 1975

Most fluorite deposits of South Korea are distributed in three metallogenic zones namly as: Hwacheon, Hwangangni and Geumsan metallogenic zones. Fluorite deposits of each zone show The characteristic features owing to the geological setting, the structural patterns and their forming processes. deposits of the Hwacheon metallogenic zone are wholly fissure filling hydrothermal veins emThe bedded in shear fractures of the granite gneiss or schists of Precambrian age or in the cooling fractures of the granite and acidic hypabyssal rocks which are assumed to be a differentiated sister rock of the granite. Localization of most fluorite veins of the region is structurally controlled by NW and EW fracture systems and genetically related to the granite intrusion which ascertained as motivating rock of the fluorite mineralization. Fluorites are in most cases accompanied by quartz, chalcedony mainly and rarely agate, calcite, barite and sulphide base metals in some localities. The deposits of the Hwangangni metallogenic zone were formed at the last stage of hydrothermal polymineralization of W, Mo, Cu, Pb, Zn. The majority of the fluorite ore bodies were originated from replacement in limestone beds of Great Limestone Series or in calcareous interbeds of metasediments, whereas some cavity-filling ore bodies were embedded in phyllites and schists of the Ockcheon system and along the fissures in the replaced beds which were originated by volume decrease. The localization of fluorite deposits in this region is genetically related to the Moongyong granite which has been dated as middle Cretaceous, and controlled structurally by the $N20^{\circ}{\sim}50^{\circ}W$ extension fracture system or axial planes of folds, and by faults of NE direction that acted as paths of ore solution. The deposits of the Geumsan metallogenic zone are seemed to be formed through the similar process as that of Hwangangni metallogenic zone, but characteristic distinctions are in that they are more prevailing fracture filling veins and large number of the deposits are localized in roof-pendants or xenolithes of limestone in granites and porphyries. Igneous rocks that presumably motivated the mineraltzation are middle Cretaceous Geumsan granite and porphyries. Metallogenic epoch of the fluorite mineralization of South Korea are puesumably limited in early-middle Cretaceous. Studies of the fluid inclusions in fluorites of the region reveal that the homogenization temperature of the fluorite deposits are as follows: Hwacheon metallogenic zone : $95^{\circ}C{\sim}165^{\circ}C$; Hwangangni metallogenic zone : $97^{\circ}C{\sim}235^{\circ}C$; Geumsan metallogenic zone : $93^{\circ}C{\sim}236^{\circ}C$. Judging from the above results, the deposits of the Hwancheon region were formed at the epithermal stage, and those in the Hwangangni and Geumsan regions, were deposited at epithermal stage preceded by mesothermal mineralization of small scale in which some sulphide minerals were deposited. The analytical data of minor elements in the fluorites reveal that ore solutions of Hwangangni metallogenic zone seemed to be emanated in more acidic stage of magma differentiation than Hwacheon metallogenic zone did.

• Economic and Environmental Geology
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• v.16 no.2
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• pp.83-109
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• 1983

The Cretaceous Palgongsan granite is a typical, calc-alkaline, subsolvus monzogranite and shows characteristics of "I-type" granite by mineralogy and chemical composition. Many of the major and trace element characteristics of the Palgongsan granite are consistent with a relationship by fractional crystallisation to form a chemically zoned pattern. The granite show light REE enrichment with (Ce/Yb)N ratios of 5.78-9.50. All the REE patterns show Eu negative anomalies which become larger from the margin ($Eu/Eu^*=0.75$) to the core ($Eu/Eu^*=0.24$) of the pluton, mainly due to feldspar fractionation. Mineral geochemistry (alkali-feldspar, plagioclase & biotite) studies also show the zonal structure of the Palgongsan granite. The two-feldspar geothermometer shows that the temperature difference between the margin and the core part of the pluton is about $200^{\circ}C$ at various assumed pressures.

• Tunnel and Underground Space
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• v.14 no.1
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• pp.69-77
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• 2004

Investigation of the time-dependent behavior of rock and the associated mechanisms are of key interest in long-term stability analysis of many engineering applications. In this study, creep tests were performed on Daejeon granite samples of 25.4mm diameter under uniaxial compression at varying stress levels. The effect of moisture was investigated by testing both air-dried and fully water-saturated samples. The creep behavior of Daejeon granite exhibited three distinctive stages of primary, secondary and tertiary creep. The ultimate strength of granite under a constant stress decreased considerably with time. Saturation and immersion of the test specimen in water markedly increased the total creep strain as well as the secondary creep rate. The experimental creep curves are fitted to Burger's model as well as two other empirical models suggested by previous researchers. A number of the parameters determined for each model are dependent on stress and influenced by the presence of water. Based on the experimental results, an empirical relation between the applied stress and the time-dependent strain is established separately for each air-dried and fully water-saturated Daejeon granite.

• Journal of Ginseng Research
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• v.28 no.1
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• pp.52-59
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• 2004

The ginsengs showing different ages(1, 2 and 3 years) are collected from the granite, phyllite and shale area. Keumsan and are analysed for the incompatible elements with the soils. In the soils, granite areas are high in the most of element and shale areas show high correlations among the element pairs. In the comparisons for differences of ginseng ages within the same area, granite and phyllite areas are high in the 2 year ginsengs while the shale ares are high in the 3 year ginsengs in the most of the elements. Positive correlations are dominant regardless area differences and high correlations are shown in the 3 year ginsengs, indicating the absorptions of the eligible element content with increasing ages. In the comparisons of area for the ginsengs of the same age, Rb, Cs and Ga, in the case of the granite area, are low in the 2 year ginsengs while most of elements are low in the 3 year ginsengs. High element contents are shown in the shale area, which are compared with granite and phyllite areas, indicating differences of dominant minerals. In the comparisons of the parts, upper parts are mainly high. High correlations are shown in the 3 year ginsengs, suggesting the similarities of absorption degrees within root as well as upper parts with the age. In the comparisons between soils and ginsengs, elements except Ba and Sr, are mainly high in the soils.

• Economic and Environmental Geology
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• v.52 no.4
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• pp.275-290
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• 2019

Geochemical study was conducted to elucidate the origin of fluorine (F) distributed in the rocks within the four areas of Yongyudo and Sammokdo, Incheon, which have been used as the source area of land reclamation for the $3^{rd}$ and $4^{th}$ stage construction sites of the Incheon International Airport. The main geology of the study area is Triassic biotite granite. Fluorine is contained at high levels in biotite granite, mylonite, and dykes (andesite and, basaltic-andesite). Furthermore, the higher concentrations of fluorine in the biotite granite can be contributed to fluorite. The results of microscopic analyses reveal that the fluorite was mostly observed as small vienlets together with quartz. This features support that fluorite was naturally formed due to the secondary process of hydrothermal fluids. In addition, fluorine was investigated to be highly enriched in a large amount of mica within the veins. In the case of mylonite, a high levels of fluorine was contributed to a large amount of sericite. The sericites contained in the mylointe, differently to those of the biotite granite, filled the micro-fractures of quartz formed as a result of mylonitization and included small cataclastic quartz grains. This indicates that fluorine was naturally enriched due to the alteration of hydrothermal fluids filling fractured zones formed by mylonitization. Consequently, the results of petrological and mineralogical study confirm that the fluorine distributed in the rocks within the Yongyudo and Sammokdo originated naturally.

• Tunnel and Underground Space
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• v.34 no.4
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• pp.330-354
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• 2024

In site characterization of high-level radioactive waste, discontinuity(joint) distribution and rock mass classification, which are key evaluation parameters in the rock engineering field, were evaluated using deep boreholes in the Wonju granite and Chuncheon granite, which belong to Mesozoic Jurassic era. To evaluate joint distribution characteristics, fracture zones and joint surfaces extracted from ATV data were used, and major joint sets were evaluated along with joint frequency according to depth, dip direction, and dip. Both the Wonju and Chuncheon granites that were studied showed a tendency for the frequency of joints to increase linearly with depth, and joints with high angles were relatively widely distributed. In addition, relatively large amounts of weathering tended to occur even in deep depth due to groundwater inflow through high-angle joints. RQD values remained consistently low even at considerable depth. Meanwhile, joint groups with low angles showed different joint characteristics from joint sets with high angles. Rock mass classification was performed based on RMR system, and along with rock mass classification for 50 m intervals where uniaxial compressive strength was performed, continuous rock mass classification according to depth was performed using velocity log data and geostatistical techniques. The Wonju granite exhibited a superior rock mass class compared to the Chuncheon granite. In the 50 m interval and continuous rock mass classification, the shallow part of the Wonju granite showed a higher class than the deep part, and the deep part of the Chuncheon granite showed a higher class than the shallow part.

• Journal of the Korean Geosynthetics Society
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• v.7 no.1
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• pp.1-6
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• 2008

In this study, the deformation and strength characteristics for non-woven geotextile-reinforced decomposed granite soil on the triaxial compression test under the same condition as the underground. The specimen of reinforced earth was made of the decomposed granite soil imbedded horizontal in a given space with non-woven geotextile. Four different type of specimen was used in this experimental programme; UR for unreinforced, R-1 for a single non-woven geotextile sheet, R-2 for two sheets, and R-3 for three sheets. According to the testing results, it was found that the strength of the reinforced soil increased when the non-woven geotextile sheets were more used. These results would be applied to the design of reinforced earth structure through the theoretical interpretation method.

• Geomechanics and Engineering
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• v.9 no.1
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• pp.101-113
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• 2015

Saturated soil hydraulic conductivity is a very important soil parameter in numerous practical engineering applications, especially rainfall infiltration and slope stability problems. This parameter is difficult to measure since it is very highly sensitive to various soil conditions. There have been many analytical and empirical formulas to predict saturated soil hydraulic conductivity based on experimental data. However, there have been few studies to investigate in-situ hydraulic conductivity of weathered granite soils, which constitute the majority of soil slopes in Korea. This paper introduces an estimation method to derive saturated hydraulic conductivity of Korean weathered granite soils using in-situ experimental data which were obtained from a variety of slope areas of South Korea. A robust regression analysis was performed using different physical soil properties and an empirical solution with an $R^2$ value of 0.9193 was suggested. Besides that this research validated the proposed model by conducting in-situ saturated soil hydraulic conductivity tests in two slope areas.

• Economic and Environmental Geology
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• v.36 no.4
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• pp.305-312
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• 2003

This study was performed to delineate the subsurface geology, geologic structure, and distribution pattern of the Palgongsan granitic body, and to reveal the relationship between the Kyeongsang basin and Yongnam massif by gravity survey. The study area is located between the latitude of 35$^{\circ}$45'-36$^{\circ}$21'N and longitude of 128$^{\circ}$15'-129$^{\circ}$00'E. Total of 966 gravity data measured by Seoul National University, KlGAM(Korea Institute of Geology, Mining ＆ Materials), Pusan National University and Yonsei University were used. The Bouguer gravity anomaly in the study area ranges from -12.88 to 26.01 mgal with a mean value of 11.27 mgal. A very low anomaly zone is located in the Yongnam massif in west of the study area. The anomaly value increases going from west to east. A low anomaly distribution in Palgongsan granite and Yongnam massif is interpreted as the effect of their lower density than that of Kyeongsang Super Group. Power spectrum analysis is applied to evaluate the average depth of basement the Kyeongsang Basin and Conrad discontinuity from gravity anomaly. The average depths of density discontinuities are calculated 10.45 km and 4.9 km, and these are interpreted as Conrad discontinuity and depth of basement of the Kyeongsang Basin, respectively. The depth of Palgongsan granite is derived by means of 2-dimensional modeling and it decreases gradually toward the east. The gravity anomaly east of the study area decreases abruptly due to Shingryeong fault and Nogosan ring fault. Two deepest and sharp roots of Palgongsan granite are recognized by 2-dimensional modeling of each profiles. The depths of those roots are 5.3 km on a profile AA' and 7 km on a profile BB' which is the maximum depth of Palgongsan granite. Small granitic bodies are also seen to be intruded around the Palgongsan granite. The root of Palgongsan granite is shown by 3-dimensional analysis based on the interpolation of 2-dimensional modeling along each profiles to exist in the southwest vicinity of Palgongsan granite. The total volume of Palgongsan granite is approximately 31.211 $Km^3$.

• Korean Journal of Mineralogy and Petrology
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• v.35 no.2
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• pp.101-109
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• 2022

The mobility and transport of radioactive cesium are crucial factors to consider for the safety assessment of high-level radioactive waste disposal sites in granite. The retardation of radionuclides in the fractured crystalline rock is mainly controlled by the hydrochemical condition of groundwater and surface reactions with minerals present in the fractures. This paper reports the experimental results of cesium sorption to the Wonju Granite, a typical Mesozoic granite in Korea, performed in an anaerobic chamber that mimics the anoxic environment of a deep disposal site. We measured the rates and amounts of cesium (¹³³Cs) removed by crushed granite samples in different electrolyte (NaCl, KCl, and CaCl₂) solutions and a synthetic groundwater solution, with variations in the initial cesium concentration (10^-5, 5×10^-6, 10^-6, 5×10^-7 M). The cesium sorption kinetic and isotherm data were successfully simulated by the pseudo-second-order kinetic model (r²= 0.99) and the Freundlich isotherm model (r²= 0.99), respectively. The sorption distribution coefficient of granite increased almost linearly with increasing biotite content in granite samples, indicating that biotite is an effective cesium scavenger. The cesium removal was minimal in KCl solution compared to that in NaCl or CaCl₂ solution, regardless of the ionic strength and initial cesium concentration that we examined, showing that K⁺ is the most competitive ion against cesium in sorption to granite. Because it is the main source mineral of K⁺ in fracture fluids, biotite may also hinder the sorption of cesium, which warrants further research.