• 한국지구과학회:학술대회논문집
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• 2005.02a
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• pp.138-144
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• 2005

석류석은 변성 온도와 압력을 계산하는 지온지압계에 널리 사용되며, 또한 이들 내부엽리와 외부엽리와의 접촉 관계를 이용하여 상대적인 변형작용의 시기를 밝히는 데 이용되어져 왔다. 석류석 반상변정 내의 내부 엽리 조직에 대한 정량적인 해석과 내부 미세 구조와 화학적 누대구조와의 관계에 대한 접근 방법은 석류석이 형성되는 동안에 온도-압력-변형작용의 진화 과정을 보다 정량적으로 해석할 수 있을 뿐만 아니라, 절대 연령 자료와 결합은 조산 운동 동안 발생하는 다변성/다변형 작용의 특징 보여주는 온도-압력-변형-시간 경로를 규명할 수 있다. 미국 메사추세츠 주 북중부 지역에서 십자석, 남정석과 함께 산출되는 석류석 반상변정은 온도-압력이 증가(540-570 $^{\circ}C$, 4.0-5.0 kbar에서 620-637 $^{\circ}C$, 7.9-8.8 kbar 까지) 하면서 성장하였다. 또한 이와 같은 변성작용 동안 압축 변형 방향은 다음과 같은 순서로, NE-SW, NW-SE, N-S 그 다음 E-W 방향으로 변화하였다. 결론적으로 이와 같은 변성작용과 변형작용은 주로 고생대 중기 데본기 동안에 일어났던 아카디안 조산운동으로 특징 지워 지며, 후기 알레게니안 조산운동에 부분적으로 영향을 받은 것으로 판단한다.

• 한국지구물리탐사학회:학술대회논문집
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• 2006.06a
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• pp.201-206
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• 2006

Earth sciences is undergoing a gradual but massive shift from description of the earth and earth systems, toward process modeling, simulation, and process visualization. This shift is very challenging because the underlying physical and chemical processes are often nonlinear and coupled. In addition, we are especially challenged when the processes take place in strongly heterogeneous systems. An example is two-phase fluid flow in rocks, which is a nonlinear, coupled and time-dependent problem and occurs in complex porous media. To understand and simulate these complex processes, the knowledge of underlying pore-scale processes is essential. This paper presents a new attempt to use pore-scale simulations for understanding physical properties of rocks. A rigorous pore-scale simulator requires three important traits: reliability, efficiency, and ability to handle complex microstructures. We use the Lattice-Boltzmann (LB) method for singleand two-phase flow properties, finite-element methods (FEM) for elastic and electrical properties of rocks. These rigorous pore-scale simulators can significantly complement the physical laboratory, with several distinct advantages: (1) rigorous prediction of the physical properties, (2) interrelations among the different rock properties in a given pore geometry, and (3) simulation of dynamic problems, which describe coupled, nonlinear, transient and complex behavior of Earth systems.

• Economic and Environmental Geology
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• v.39 no.1 s.176
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• pp.27-38
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• 2006

To understand the geologic and hydrogeochemical controls on the occurrence of high fluoride concentrations in bedrock groundwaters of South Korea, we examined a total of 367 hydrochemistry data obtained from deep groundwater wells (avg. depth=600 m) that were drilled fur exploitation of hot springs. The fluoride concentrations were generally very high (avg. 5.65mg/L) and exceeded the Drinking Water Standard (1.5 mg/L) in $72\%$ of the samples. A significant geologic control of fluoride concentrations was observed: the highest concentrations occur in the areas of granitoids and granitic gneiss, while the lowest concentrations in the areas of volcanic and sedimentary rocks. In relation to the hydrochemical facies, alkaline $Na-HCO_3$ type waters had remarkably higher F concentrations than circum-neutral to slightly alkaline $Ca-HCO_3$ type waters. The prolonged water-rock interaction occurring during the deep circulation of groundwater in the areas of granitoids and granitic gneiss is considered most important for the generation of high F concentrations. Under such condition, fluoride-rich groundwaters are likely formed through hydrogeochemical processes consisting of the removal of Ca from groundwater via calcite precipitation and/or cation exchange and the successive dissolution of plagioclase and F-bearing hydroxyl minerals (esp. biotite). Thus, groundwaters with high pH and very high Na/Ca ratio within granitoids and granitic gneiss are likely most vulnerable to the water supply problem related to enriched fluorine.

• Economic and Environmental Geology
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• v.31 no.3
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• pp.201-213
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• 1998

From the Jungwon and Munkyeong areas which are among the famous producers of the carbonate-type groundwaters in Korea, various kinds of natural waters (deep groundwater, shallow groundwater and surface water) were collected between 1996 and 1997 and were studied for hydrogeochemical and environmental isotope (${\delta}^{34}S_{so4}$, ${\delta}^{18}O$, ${\delta}D$)systematics. Two types of deep groundwaters (carbonate type and alkali type) occur together in the two areas, and each shows distinct hydrogeochemical and environmental isotope characteristics. The carbonate type waters show the hydrochemical feature of the 'calcium(-sodium)-bicarbonate(-sulfate) type', whereas the alkali type water of the 'sodium-bicarbonate type'. The former type waters are characterized by lower pH, higher Eh, and higher amounts of dissolved ions (especialJy, $Ca^{2+}$, $Na^{+}$, $Mg^{2+}$, $HCO_3{^-}$ and $SO_4{^{2-}}$). Two types of deep groundwaters are all saturated or supersaturated with respect to calcite. Two types of deep groundwaters were both derived from pre-thermonuclear (about more than 40 years old) meteoric waters (with lighter 0 and H isotope data than younger waters, i.e., shallow cold groundwaters and surface waters) which evolved through prolonged water-rock interaction. Based on the geologic setting, water chemistry, and environmental isotope data, however, each of these two different types of deep groundwaters represents distinct hydrologic and hydrogeochemical evolution at depths. The carbonate type groundwaters were formed through mixing with acidic waters that were derived from dissolution of pyrites in hydrothermal vein ores (for the Jungwon area water) or in anthracite coal beds (for the Munkyeong area water). If the deeply percolating meteoric waters did not meet pyrites during the circulation, only the alkali type groundwaters would form. This hydrologic and hydrogeochemical model may be successfully applied to the other carbonate type groundwaters in Korea.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2001.04a
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• pp.19-21
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• 2001

The Shiheung mine was closed in 1972 and has been abandoned since then. Although some restoration work has been done, there still remain mine failings in and around the mine, posing a potential environmental hazard. Mine tailings and the porewater extracted from the tailing were investigated to see any evidence of elemental release and migration to adjacent groundwater and soil in the field. The pHs of the tailing range from 6.24 to 7.23. Calcite in the studied area seems to influence on such neutral pH range. Depth profile of mine tailing demonstrate elements have been leached and removed as a consequence of weathering during disposal. This is also supported by the findings from porewater analysis, corresponding the trends in the mine tailings. The concentrations of Cu, Cd, Pb, Zn in the tailing porewater exceed the standard value of EPA for drinking water and this implies groundwater can be contaminated through infiltration of the porewaters, which ultimately will be discharged as leachate from the mine tailing. Groundwater samples collected near the mine area do not show high metal concentrations, except for Fe, which were detected over drinking water standard.

• Journal of the Mineralogical Society of Korea
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• v.24 no.4
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• pp.289-300
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• 2011

Atomistic origins of carbon solubility into silicates are essential to understand the effect of carbon on the properties of silicates and evolution of the Earth system through igneous and volcanic processes. Here, we investigate the atomic structure and NMR properties of dissolved carbon in enstatite using Raman spectroscopy and quantum chemical calculations. Raman spectrum for enstatite synthesized with 2.4. wt% of amorphous carbon at 1.5 GPa and $1,400^{\circ}C$ shows vibrational modes of enstatite, but does not show any vibrational modes of $CO_2$ or ${CO_3}^{2-}$. The result indicates low solubility of carbon into enstatite at a given pressure and temperature conditions. Because $^{13}C$ NMR chemical shift is sensitive to local atomic structure around carbon and we calculated $^{13}C$ NMR chemical shielding tensors for C substituted enstatite cluster as well as molecular $CO_2$ using quantum chemical calculations to give insights into $^{13}C$ NMR chemical shifts of carbon in enstatite. The result shows that $^{13}C$ NMR chemical shift of $CO_2$ is 125 ppm, consistent with previous studies. Calculated $^{13}C$ NMR chemical shift of C is ~254 ppm. The current calculation will alllow us to assign potential $^{13}C$ NMR spectra for the enstatite dissolved with carbon and thus may be useful in exploring the atomic environment of carbon.

• Journal of Conservation Science
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• v.25 no.3
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• pp.299-316
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• 2009

The Goryeo roof tiles from the Oegol site in Tangjeong, Asan are classified into three groups in color such as gray, red yellow and gray-yellow groups, respectively. While each group of tiles shows characteristic specific gravity, absorption ratio, LOI and vitrification degree, mineral content and distribution, and chemical composition are generally homogeneous among all groups of roof tiles. Also, all roof tiles and soils from the site show similar geochemical behavior of elements and clay-mineralization degree. This indicates that the soil from the site is probable to be a raw material of the roof tiles. Firing temperature of the roof tiles is estimated as 950 to $1,050^{\circ}C$ for the gray group, 800 to $900^{\circ}C$ for the red yellow group, and 900 to $950^{\circ}C$ for the gray-yellow group. In conclusion, roof tiles from the Oegol site is interpreted to be made of local clay without additive minerals, applying various firing conditions and standardized purifying process of raw clay materials.

• Economic and Environmental Geology
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• v.34 no.5
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• pp.461-470
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• 2001

The Shihung mine was restored in the early 90's after abandonment for 20 yews since 1973. Although disposed mine tailings were removed and the site was replaced by an incineration plant, still some residual mine tailings remain in the places including the old mine tailing ditposal area and the adjacent agricultural area. These residual mine tailings are prone to impose an adverse impact on the soil and groundwater and needs investigation for the potential contamination. Mine tailing samples were collected from the old tailing disposal area and the iii paddy. The porewater from the mine tailing were extracted and analysed to investigate chemical changes along the reaction path. Batch leaching tests were also carried out in the laboratory to find any supporting evidence found in the field analysis. Evidence of elemental leaching was confirmed both by the mine tailing and the porewater chemistry in them. The element concentrations of Cu, Cd, Pb, Zn in the porewater exceed the standard for drinking water of Korean government and US EPA. Leaching of heavy metals from the mine tailing seem to be responsible for the contamination. In batch leaching test. heavy metals were either continuous1y released or declined rapidly. Combining the information with porewater variation with depths and the geochemical meodeling results, most of elements are controlled by dissolution and/or precipitation processes, with some solubility controlling solid phases (Cu, Pb, Fe and Zn). Batch leaching test conducted at fixed pH 4 showed much higher releases for the heavy metals up to 400 times (Zn) and this area is becoming more vulnerable to soil and groundwater pollution as precipitation pH shifts to acidic condition.

• Journal of the Korean Society of Groundwater Environment
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• v.4 no.4
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• pp.199-211
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• 1997

As a part of study on geological disposal of radioactive waste, hydrogeochemical characteristics of deep granitic groundwater in Korea were investigated through the construction of a large geochemical dataset of natural water, the examination on the behaviour of dissolved constituents, and the consideration of phase stability based on thermodynamic approach. In granitic region, the contents of total dissolved solids increase progressively from surface waters to deep groundwaters, which indicates the presence of more concentrated waters at depth due to water-rock interaction. The chemical composition of groundwater evolves from initial $Ca^{2＋}$－(C $l^{－}$＋S $O_4$$^{2-}$) or $Ca^{2＋}$-HC $O_3$$^{－}$ type to final N $a^{＋}$-HC $O_3$$^{－}$ or N $a^{＋}$－(C $l^{－}$＋S $O_4$$^{2-}$) type, via $Ca^{2＋}$-HC $O_3$$^{－}$ type. Three main mechanisms seem to control the chemical composition of groundwater in the granitic region; 1) congruent dissolution of calcite at shallower depth, 2) calcite precipitation and incongruent dissolution of plagioclase at deeper depth, and 3) kaolinite-smectite or/and kaolinite-illite reaction at equilibrium at deeper depth. The behaviour of dissolved major cations (C $a^{2＋}$, $K^{＋}$, $Mg^{2＋}$, M $a^{＋}$) and silica is likely to be controlled by these reactions.

• Journal of the Mineralogical Society of Korea
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• v.24 no.1
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• pp.31-36
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• 2011

Meteorites are extraterrestrial solid rock fragments that fell from the outer space. Investigating mineral magnetic properties of the Meteorites is essential in understanding the evolution of planets and asteroids in the Solar System. In particular, magnetic characterization of magnetic mineral can provide constraints on the progress of differentiation in ancient planetary bodies. In the present study, ratio of thermoremanent magnetization (TRM) over saturation isothermal remanent magnetization (SIRM) was applied to diagnose the magnetic minerals in meteorites and igneous rocks. Distinctive classification of TRM/SIRM suggests that kamacite, tetrataenite, magnetite, and (Cr,Ti)-rich iron oxide are responsible for the magnetization of H5 Richardton, LL6 St. Severin, ALH84001, and DaG476, respectively. The TRM/SIRM ratio could be an efficient tool in identifying magnetic minerals especially when rocks or meteorites contain unstable material under heating.