• Economic and Environmental Geology
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• v.53 no.2
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• pp.159-166
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• 2020

In this research, we investigate the effect of microwave pretreatment on the recovery of gold from the gold concentrates by thiourea leaching. The changes in mineral phases by decomposition of pyrites in the gold concentrates using microwave were observed, and the result of microwave irradiation showed that the temperature of the irradiated sample increases with increasing irradiation time. With the reaction of temperature increases, Sulfur (S) in pyrites was converted to sulfur dioxide (SO₂), and then the content of S in the sample was reduced. The analytical results of XRD and SEM-EDS showed that pyrites are converted to magnetite and hematite, and its surfaces are changed to a porous shape where micro-cracks are developed. The Au leaching efficiency from the irradiated gold concentrates using thiourea-mixed solvent increased with the increases of irradiation time and solvent concentration. The experimental results considering leaching parameters indicate that the mechanism of microwave irradiation increases the maximum leaching efficiency and leaching rate of the gold concentrates, and the solvent does a role for the increasing of leaching rate constant.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2018.10a
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• pp.41-41
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• 2018

차꼬리고사리(Asplenium trichomanes L.)는 남방계식물로 제주도에 자생하는 것으로 알려져 있으며, 잎에 광택이 있고 총생하는 식물이다. 주로 실내 외 조경 및 분화소재로 이용되며, 한방에서는 철각봉미초라하여 뿌리를 포함한 전초를 이질, 임병, 만성질염, 월경불순 및 요통의 약재로 사용한다. 또한 식물구계학적 특정식물종 IV급, 적색자료목록 준위협 (NT)에 분류된 식물로 보호가 필요하다. 본 연구는 차꼬리고사리의 대량생산을 위한 기내전엽체 증식 및 기외포자체 형성조건을 구명하고자 수행되었다. 실험재료는 포자를 기내 발아시켜 전엽체를 획득한 다음 8주 간격으로 계대하면서 확보하였다. 전엽체의 증식과 생육에 적합한 배지를 비교하고자, 1/4, 1/2, 1, 2MS와 Knop배지를 조성하여 배양하였다. 배양은 전엽체 300mg을 메스로 균일하게 다지는 방법을 이용하였으며, 배양환경은 온도 $25{\pm}1.0^{\circ}C$, 광도 $30{\pm}1.0{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$, 광주기 16/8h(light/dark)로 조절되었다. 실험결과, 1MS배지에 배양된 전엽체의 생체중이 4.3g으로 가장 많이 증가하였다. 형태형성발달도 하트형의 전엽체로 정상적으로 유도되었으며, 생식기관도 관찰되었다. 전엽체로부터 포자체의 형성을 유도하고자, 원예상토, 피트모스, 펄라이트 및 마사토의 비율을 5종류로 달리하여 혼합된 토양을 사각분($7.5{\times}7.5{\times}7.5cm$)에 충진하였다. 전엽체 1g과 증류수 25mL를 핸드블랜더로 10초간 분쇄하여 토양표면에 분주하는 실험방법을 사용하였다. 재배환경은 온도 $25{\pm}1.0^{\circ}C$, 광도 $43{\pm}2.0{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$, 광주기 16/8h(light/dark)로 유지하면서 12주간 재배되었다. 실험결과, 원예상토 단용, 원예상토와 펄라이트가 2:1(v:v)로 혼합된 토양, 원예상토와 마사토가 2:1(v:v)로 혼합된 토양에서 각 31.7, 24.3, 19.3개의 포자체가 생산되었다. 한편 포자체의 생육은 원예상토 단용 토양에서 엽수, 엽장, 엽폭 등의 수치가 비교적 우수하였다. 따라서 차꼬리고사리의 전엽체는 MS배지에 배양하고 증식된 전엽체를 원예상토에 분주하여 포자체의 형성을 유도하는 것이 가장 효과적이었다.

• Economic and Environmental Geology
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• v.39 no.1 s.176
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• pp.1-7
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• 2006

This paper attempts to locate and define a quartzite deposit in Geochang, Kyongsangnam Province in order to establish its commercial viability. The quartzite deposit (Poongwon Mine) occurs as lens or boudinage at the contact between mica schist of the Deogyusan formation and granite gneiss. During Precambrian, regional metamorphism and granitization may have caused the formation ot quartzite layers through recrystallization and rearrangement of silica components derived from older sedimentary rocks, probably chert and/or sandstone. The deposit is composed of fine-grained milky, or light yellowish quartz showing weak laminations with fairly dense and rough appearance in outcrop. It reaches about $60\;m(height)\times140\;m(length)\times35m(width)$ with attitude of $N57^{\circ}E-N8^{\circ}4E\;and\;51^{\circ}-60^{\circ}NW$. The average grade of the quartzite samples is $SiO_2=94.4\;wt\%,\;A1_2O_3=3.3\;wt\%,\; Fe_2O_3=0.8\;wt\%,\;K_2O=0.7\;wt\%$, which can be used for foundry, constructional materials, or concrete making. The proved reserve was estimated as 200,811 tonnage.

• Economic and Environmental Geology
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• v.32 no.5
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• pp.445-454
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• 1999

The Sanjeon Au-Ag deposit consists of three subparallel hydrothermal quartz-calcite veins which filled fault-related fractures (generally $N20^{\circ}$ to 35"W-trending and $70^{\circ}$ to $80^{\circ}$ SW-dipping) within quartz porphyry. The vein mineralization shows an apparent variation of mineral assemblages with paragenetic time: (1) early, white quartz + pyrite + arsenopyrite + brown sphalerite, (2) middle, white (vein) to clear quartz (vug) + base-metal sulfides + electrum + argentite, (3) late, calcite + pyrite + native silver. Mineralogic and fluid inclusion data indicate that gold-silver minerals were deposited at temperatures from 2l $0^{\circ}$ to $250^{\circ}$ with salinities of 4 to 5 wt. % equiv. NaCl and log fS2 values from -14.0 to -12.2 atm. The linear relationship between homogenization temperature and salinity data indicates that gold-silver deposition was a result of meteoric water mixing. Ore mineralization occurred at pressure conditions of about 70 bars, which corresponds to the mineralization depths of about 260 m to 700 m. There is a remarkable decrease of the calculated 1)180 values of water from 1.3 to -9.7%0 in hydrothermal fluid with increasing paragenetic time. This indicates a progressive increase of meteoric water influx in the hydrothermal system at the Sanjeon deposit. Oxygen-hydrogen, sulfur, and carbon isotope values of hydrothermal fluids indicate that the ore mineralization was formed largely from meteoric waters with the contribution of sulfur and carbon from a deep igneous source.

• Economic and Environmental Geology
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• v.28 no.4
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• pp.395-404
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• 1995

The geologic structure of the Cheju volcanic island has been investigated by analyzing the gravity and magnetic data. Bouguer gravity map shows apparent circular low anomalies at the central volacanic edifice, and the maximum difference of the anomaly values on the island appears to be 30 mgal. The subsurface structure of the island is modeled by three-dimensional depth inversion of gravity data by assuming the model consists of a stacked grid of rectangular prisms of volcanic rocks bounded below by basement rocks. The gravity modeling reveals that the interface between upper volvanic rocks and underlying basement warps downward under Mt. Halla with the maximum depth of 5 km. Magnetic data involve aeromagnetic and surface magnetic survey data. Both magnetic anomaly maps show characteristic features which resemble the typical pattern of total magnetic anomalies caused by a magnetic body magnetized in the direction of the geomagnetic field in the middle latitude region, though details of two maps are somewhat different. The reduced-to-pole magnetic anomaly maps reveal that main magnetic sources in the island are rift zones and the Halla volcanic edifice. The apparent magnetic boundaries inferred by the method of Cordell and Grauch (1985) are relatively well matched with known geologic boundaries such as that of Pyosunri basalt and Sihungri basalt which form the latest erupted masses. Inversion of aeromagnetic data was conducted with two variables: depth and susceptibility. The inversion results show high susceptibility bodies in rift zones along the long axis of the island, and at the central volcano. Depths to the basement are 1.5~3 km under the major axis, 1~1.5 km under the lava plateau and culminates at about 5 km under Mt. Halla. The prominent anomalies showing N-S trending appear in the eastern part of both gravity and magnetic maps. It is speculated that this trend may be associated with an undefined fault developed across the rift zones.

• Economic and Environmental Geology
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• v.41 no.1
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• pp.1-14
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• 2008

The Bongsang gold-silver deposit consists of quartz veins that fill along the fault Bone within Cretaceous andesitic lapilli tuff. Mineralization is occurred within fault-breccia zones and can be divided into two stages. Stage I which can be subdivided into early and late depositional stages is main ore mineralization and stage II is barren. Stage I began with deposition of wall-rock alteration minerals and base-metal sulfides, and was deposited by later native silver, Ag-bearing tetrahedrite, polybasite and base-metal sulfides such like pyrite, sphalerite, chalcopyrite and galena. Fluid inclusion data indicate that homogenization temperatures and salinities of stage I range from 137 to $336^{\circ}C$ and from 0.0 to 10.6 wt.% NaCl, respectively. It suggests that ore forming fluids were cooled and diluted with the mixing of meteoric water. Also, temperature and sulfur fugacity deduced mineral assemblages of late stage I are $<210^{\circ}C\;and\;<10^{-15.4}$ atm, respectively. Sulfur(3.4%o) isotope composition indicates that ore sulfur was mainly derived from a magmatic source as well as the host rocks. The calculated oxygen{2.9%o, 10.3%o(quartz: 7.9%o, 8.9%o, calcite: 2.9%o, 10.3%o)}, hydrogen(-75%o) and carbon(-7.0%o, -5.9%o) isotope compositions indicate that hydrothermal fluids may be meteoric origin with some degree of mixing of another meteoric water for paragenetic time.

• Economic and Environmental Geology
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• v.43 no.2
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• pp.149-162
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• 2010

The most serious problem in oil stockpiles with artificial underground cavern is maintaining the stability of ground water system. In order to understand the ground water system around K-1 site, we determined the regional flow direction and level distribution of groundwater, and investigated the major geologic factors influencing their flow system. Reactivated surface along the contact between granite and gneiss, and fractures and faults along the long acidic dyke may contribute as important pathways for groundwater flow. Within K-1 site, groundwater level fluctuation is closely related to the rainfall events and injection from surface or influx water. In this project, the effect of groundwater pumping from the southern wells was examined. Based on equations relating water level drawdown to pumping rate at those wells, their pumped outflow of groundwater ranged from $80\;m^3$/day to less than $250\;m^3$/day. The modeling results with MODFLOW imply that the previous groundwater pumping at distance of 1.2 km may not affect the groundwater level variations of the K-1 site. However, continuous pumping work at quantity over $250\;m^3$/day in this area will be able to affect the groundwater system of the K-1 site, particularly along the acidic dyke.

• Economic and Environmental Geology
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• v.41 no.3
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• pp.359-372
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• 2008

A number of researches on disaster risk reduction using the most advanced equipments and scientific technologies have been performed to minimize the damage of property and to protect human life. Although the Korean government is trying to enlarge the research area for disaster risk reduction, the investment size and the applicable results in this area have stayed in the lower level comparing to other scientific fields in Korea and the same field in advanced countries. However, the National Emergency Management Agency (NEMA), a government Agency which is responsible for disaster management coordination, was established in June 2004 establishing an efficient and well-organized system to cope with various disasters. In this study, investment size by the government was evaluated and associated areas were also identified. We also analyzed the roles on research and development for disaster risk reduction among different government Ministries were analyzed and role assignment to each Ministry was proposed. The role assignment has been concreted by conducting the process of approval in the government.

• Economic and Environmental Geology
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• v.37 no.2
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• pp.245-253
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• 2004

The 36km-long Daebo-Campo coast has a well-developed marine terraces divided to six steps by elevation of paleoshoreline : 0.5 m(T1), 10 m(T2), 30 m(T3), 40 m(T4), 60 m(T5) and 75 m(T6). The 2$^{nd}$ and 3$^{nd}$ platforms in Daebo to Guryongpo are wider and more distinctive than those of Guryongpo to Gampo. The 3$^{nd}$ terrace of 30 m high is subdivided to two flights as lower(T3b) and upper(T3a) by old sea cliff. Platform age is unclear because of coral fossil free. However, the terrace age could be determined with convergent OSL ages from beach sediments on 2$^{nd}$ step(T2). OSL ages of the terrace of 10 m high range in 60-70 ka. It reveals that the 2$^{nd}$ -step platform correlates to Oxygen Isotope Time scale, substage 5a(ca. 80 ka), and that uplift rate is ca. 0.19 m/ka for 2$^{nd}$ terrace at Daebo-Campo coast. If considering equivalent uplift rate for all terraces since the Late Pleistocene, the 3$^{rd}$ and 4$^{th}$ terraces would be 5e substage and 7 stage. The 30 m-high terrace provides a good indicator for uplift at Daebo-Gampo coast since 125,000 yrs(MIS 5e). It suggests that the local neotectonic deformation might cause an optional uplift rate of ca. 0.19 m/ka along the SE coast of Korea.

• Economic and Environmental Geology
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• v.15 no.1
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• pp.41-47
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• 1982

Typical stratigraphic sequences of Paleozoic form the Baegunsan Syncline (equal to Hambaeg Syncline) and Taebaegsan Group is the basement in the southern part of Kangweon Province. Deformation pattern depends on their stratigraphic site and their internal properties. In the biotite schists and meta-sandstones of Pre-Cambrian sequences, flow folds and ptygmatic folds are developed, and high strain deformation is pervasive. Deformational patterns of Cambro-Ordovician are variable because of their various formations. Fracturing is pervasive in the Jangsan Quartzite and Daegi and Maggol Limestone. Welldeveloped slaty cleavage and angular folds of kink and chevron types are the prevailing structures of pelitic rocks. The most characteristic feature of limestone alternated with argillite is the "Compositional cleavage (Author's proposal)" known as the "Worm-eatern" structures. It was known that this structures have a sedimentary origin. But their preferred orienation of long axis of erosional lime holes, originated from tectonic deformation of folding. And this structures have the same character as the axial plane cleavages. Fracturing and long wave concentric folds are dominant characters of the Upper Paleozic sequences. In this area, two folds are superimposed. Field studying and analysis of structures show that the cross-folds of NS-direction are pervasive and were deformed by the EW-directional Baegunsan Syncline. The cross-folding is the major and penetrative deformation and prior to Baegunsan Syncline.