• Economic and Environmental Geology
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• v.19 no.spc
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• pp.113-119
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• 1986

A characteristic mineralogical zonal distribuion is observed in a large scale(whole ore- body) small scales(handy specimens). They show similar chemical variations: most of elements except CaO were supplied by hydrothermal fluids to form skarns. Garnets occuring in the pyroxene-garnet skarn have a wide range of chemical composition ranging from andradite to grossularite, while individual grains of the garnets also show a similar zonation of chemical composition varied between grossularite and andradite. Highly contained Mo-bearing scheelites are generally concentrated in the central part of the Sang- dong skarn orebody. Similarly, some large grains of scheelite show a nice zonation due to different contents of Mo, highly enriched in the core of the scheelite crystal. This geochemical similarity in the large scale and small scales suggests the Sangdong skarn formation was achieved under a certain chemical environment, and detailed studies on a small scale texture could be a clue to understand a whole ore deposit.

• Journal of Korean Society for Atmospheric Environment
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• v.26 no.2
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• pp.107-117
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• 2010

The atmospheric geochemistry of mercury is generalls represented by gaseous elemental phase that exhibits the high environmental mobility and relatively long atmospheric residence time (c.a., 1 year) with its high chemical stability. In the recognition of the environmental significance of its global cycling, enormous efforts have been devoted to the measurements of Hg exchange across air-soil boundary. To be able to describe the fundamental aspects on this subject, the current development in the measurements of atmospheric exchange rates of mercury has been summarized using the current database reported worldwide. As a first step, different techniques commonly employed in its measurements are introduced with the discussions on their merits and disadvantages. Then, the results derived from various field measurement campaigns are also compared and discussed. The direction for the future study of mercury is presented at last.

• Economic and Environmental Geology
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• v.32 no.2
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• pp.141-150
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• 1999

The granitic rocks are distributed in the northeastern Gyeongsang basin, and are subdivided into the Youngduk, Younghae, Jangsadong and Onjeong granite. Based on the chondrite normalized patterns of REE by primitive mantle, the Jangsadong granite is more negative Eu anomaly than other granites. On the patterns of trace and rare earcth elements normalized by primitive mantle, Sr, P, Nd, Sm and Ti contents of t도 Youngduk and Younghae granites are higher than those of Jangsadong and Onjeong granites. Based on K-Ar ages, the Youngduk granite is 166.5 Ma for biotite, Younghae granite is 158.7 to 178.0 Ma for hornblende, Jangsadong granite is 113.8 to 118.4 Ma for K-feldspar and hornblende, and Onjeong granite is 67.4 Ma for biotite. Thus, geochemical and geochronological results suggest two plutonic episodes :the Youngduk-Younghae granites and Jangsadong-Onjeong granites suggest two plutonic episodes : the Youngduk-Younghae granites and Jangsadong-Onjeong granites. Jurassic plutonism cooled faster than Cretacous plutonism in the study area.

• Economic and Environmental Geology
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• v.29 no.4
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• pp.471-481
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• 1996

Clay mineral geothermometry using sericites and chlorites in Bobae sericite mine reveals that these clay minerals formed at relatively high temperature. It appears that sericites formed at around $200{\sim}350^{\circ}C$ and chlorites formed at around $250^{\circ}C$. X-ray diffraction study of these minerals reveals that sericite $2M_1$ type and chlorite IIb type are dominant phases. Both polytypes indicate that the precipitation temperatures of these minerals shows fairly good agreement with the estimated temperature by clay mineral geothermometry. The Bobae sericite mine was formed at relatively higher temperature than several non-metal ore deposits occurred in the southern part of Korea.

• Economic and Environmental Geology
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• v.21 no.3
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• pp.319-329
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• 1988

As a factor which can help to understand the genesis of (mata) sedimentary and/or hydrothermal uranium depisits, an interpretation of the role of organic matter associated with uranium mineralization, was attempted with the literature published up to the end of 1986. Laboratory studies, in which diageneis and metamorphism are artificially simulated, can help to elucidate how uranium with particular organic materials are formed and destroyed. Similarly, research involving a variety of techniques is needed to characterize both the soluble organic extracts (bitumen) and the insoluble organic matter (kerogen), separated from uranium ores and associated rocks. In the presence of clay minerals and amorphous oxy-hydroxde minerals, an understanding of the role of organic matter must be prudent and may require the incorporation of multidisciplinary approach (mineralogy, inorganic geochemistry ...).

• Proceedings of the KSEEG Conference
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• 2003.04a
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• pp.330-330
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• 2003

Several volcanics are found within the Tertiary sedimentary basins, southeastern part of Korea. The sedimentary basins have been interpreted to have formed in the framework of separation of the East Sea. The volcanics are Eocene or Early and Middle Miocene in ages, showing a distincetve chronological gap, and show mafic and silicic (bimodal) in composotion. The Miocene volcanics were regionally and stratigraphically grouped into two varieties along the Hyeongsan fault; younger volcanics (13.6-15.2 Ma, K) from the north of the fault, erupted after the opening of the East Sea, and older volcanics (16.2-21.1 Ma) from the south of the fault. (omitted)

• Journal of Environmental Impact Assessment
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• v.17 no.6
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• pp.321-333
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• 2008

Considering risks and artificial enrichments of metals in the soils of the study area, the study aims to analyze geology, grain size and geochemistry. Geology is mainly composed of gneisses and phyllites of metamorphic rocks, sandstones, siltstones, shales, tuffs of sedimentary ones and granites and andesites of igneous ones in the area. In the area, mean contents of metals are not meaningful in accordance with petrogenesis. The soil textures of the area are of S, lS and sL of sandy soil, L, scL, cL of loam and C, zC and sC of clayey soil. Mean contents of Ni, Cr, Co and Cu are meaningfully high in loam and clayey soil relative to sandy soil, whereas Ni, Zn, Cd contents are higher in clayey soil than in loam. Those differences imply the metallic contents are dependent to grain size. Based on the metal contents in the soils of the study area, Cu and Zn in loams and Pb in sandy soils are corresponded to soil contamination warning standards, and As showing 75mg/kg of maximum content in loams is assigned to soil contamination countermeasure standards, respectively. Artificial enrichment factor minimized wall rock and grain size relations is over 1 in Cr, Ni and Cu, but the factor is below 1 in average of other metals.

• Economic and Environmental Geology
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• v.30 no.1
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• pp.15-23
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• 1997

Gold mineralization of the Ogkye gold mine was deposited mainly in quartz veins up to 150 cm wide which occupy fissures in Cambrian Pungchon limestone. Ore minerals are relatively simple as follows: pyrite, arsenopyrite, pyrrhotite, sphalerite, electrum and galena. On the basis of the Ag/Au ratio on ore grades, mode of occurrence and assoicated mineral assemblages, the Ogkye gold deposit can be classified as pyrite-type gold deposit (Group IIB). Fluid inclusion data indicate that ore minerals were deposited between $400^{\circ}$and $230^{\circ}C$ from relatively dilute fluids (0.2 to 7.3 wt.% eq. NaCl) containing $CO_2$. The ore mineralization resulted from a complex history of $CO_2$ effervescence and local concomitant boiling coupled with cooling and dilution of ore fluids. Gold deposition was likely a result of decrease of sulfur activity caused by sulfide deposition and/or $H_2S$ loss accompanying fluid unmixing. Sulfur isotope compositions of sulfide minerals (${\delta}^{34}S=3.5{\sim}5.9$‰) are consistent with ${\delta}^{34}S_{H_2S}$ value of 4.8 to 6.1‰, suggesting mainly an igneous source of sulfur partially mixed with wall-rock sulfur.

• Economic and Environmental Geology
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• v.35 no.4
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• pp.373-378
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• 2002

Among the science and engineering fields in North Korean Academy of Sciences, geology occupies about 10 percent of the total number of departments. An analysis of major geologic research fields in North Korea, based on the number of authors of 2000-200l publications in a representative journal "Geology and Geography", shows the proportions as follows: mineralogy and petrology (31.0%), stratigraphy and paleontology (12.3%), economic geology and geochemistry (11.6%), geophysics and structural geology (14.2%), and applied geology (31.0%). This proportion is similar to that in South Korea in 1960s and shows that geologic research activity in North Korea is concentrated for the purpose of mineral resources exploration. The academic collaboration between South and North Korea in near future should include the researches on the reconstruction of geologic history in Korean peninsula and Northeast Asia and the environmental restoration from mining-related environmental pollution in North Korea. For active academic interchange between South and North Korea, efforts to overcome the academic gap are requisite. Frequent joint symposia, interchange programme of post-doctoral fellows, and cooperative researches on specific topics are recommended for this effort.

• Economic and Environmental Geology
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• v.30 no.4
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• pp.363-369
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• 1997

As a part of the study to know the deep geological structure of the Ogcheon Zone. gravity survey is performed along the survey line of which direction is roughly perpendicular to major faults of the Zone. Recent studies for petrology. geochemistry. and structural geology in south-western Ogcheon Zone are outlined. Raw gravity data are corrected to obtain Bouguer anomalies and the anomalies are interpreted to obtain subsurface structures along the survey line. The subterranean density discontinuities determined from the power spectrum method are appeared at depths of 15.4 km and 2.8 km. It is considered that the depth of 15.4 km indicates the boundary between upper and lower crust. Probably the depth of 2.8 km represents the boundary between upper volcanic formations and granites. Alternatively. the observed Bouguer anomalies are interpreted in terms of lateral density variation model. Finally. the subterranean geological structure to satisfy the Bouguer anomalies is presented through the iterative forward method in which results obtained from surface geological informations and from the inverse method are adopted as an initial model.