• The Journal of the Petrological Society of Korea
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• v.9 no.1
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• pp.40-50
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• 2000

This study is aimed at elucidating the source rocks of the Hayang strata in the northeastern part of the Gyeongsang Basin. Zircon morphology was analyzed for sandstones from the Iljig, Hupyeongdong, and Jeomgog formations of the Hayang Group and Precambrian gneisses and Jurassic granites. Generally, the composite zircon crystals extracted from the basement rocks and the Hayang Group sandstones show short prismatic to middle prismatic shapes. {110)={100) prism type is dominant and (101) pyramid is the average of the zircon morphology data. Zircon index@) and the shape trend characteristics clearly show that the zircon crystal forms of the Iljig and Hupyeongdong sandstones are dominantly similar to those of the biotite banded gneiss and granite gneiss of Precambrian age. Zircon morphology of the Jeomgog sandstones is dominantly similar to those of the Jurassic granites. Referring to the reported paleocurrent result, the source rocks of the Iljig and Hupyeongdong formations are mainly the Precambrian gneisses distributed in the southeastern and northeastern parts, respectively. And Jeomgog sandstones were mainly derived from Cheongsong granite at Cheongsong uplift region in the eastern part. At the time of completion of the Hupyeongdong sedimentation, the Precambrian basement rocks were severely eroded and formed low topography. During the Jeomgog period, the Jurassic granites which intruded the Precambrian basement began to crop out on the surface. The basin widely extended toward the east and the exposed Jurassic granite of Cheongsong uplift region actively supplied the sediments to the basin.

• The Journal of the Petrological Society of Korea
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• v.13 no.4
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• pp.191-200
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• 2004

The Ubo fault Bone, which cross over the northwestern to southeastern direction at the Hwabuk damsite in Hakseongri, Gunwigun, Gyeongsangbukdo Province, has length about 20km. The Ubo fault zone in this area is segmented to several small faults and makes a gentle slope and hill along the right side of the drainage in the Hwabuk dam. In the storage area of Hwabuk dam, 2 pairs of faults occur and the width of fracture zones are about 2m. To define the fracture Bone using the geochemical data, the samples were collected at 0.5m, 1m, 2m, 4m, 8m, 16m and 32m apart from the center of the main fracture Bone toward north and south, respectively, and analyzed for major elements and mineral content Approaching the fracture Bone, Fe$_2$O$_3$, MgO, K$_2$O, quartz, muscovite and chlorite are increasing and Na$_2$O, CaO, plagioclase and biotite are decreasing, respectively. Based on the rock chemistry and mineral content, the range of the main fracture zone affected by the Ubo fault at Hakseongri is 2m width in total, the secondary deformed zone is 8m width in total. Finally the maximum affected range by the Ubo fault is inferred to 16m width in total.

• Journal of Korea Water Resources Association
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• v.54 no.10
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• pp.807-817
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• 2021

In this study, assessment of vulnerability in the management of spatio-temporal groundwater resources considering the surface waterground water interactions was conducted in administrative districts of mountainous regions in Korea. Mountainous regions were classified into four regions and spatial groundwater resources management vulnerability assessment criteria were selected to consider the surface water-ground water interactions. Paju in the central mountainous region, Gapyeongin the mountains region, Gurye in the southwestern mountainous region, and Yangsan in the southeastern mountainous region were selected as a result of the selection of vulnerable area for groundwater resources management. Assessment of the Monthly vulnerability to groundwater resource management due to changes in groundwater levels and infiltration was carried out in the selected areas. As a result of monthly vulnerability to groundwater resources management, December ~ Feburary was assessed as vulnerable to groundwater resource management. The results of this study are expected to contribute to the more efficient groundwater resource management measures by administrative district

• 한국해양학회지
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• v.24 no.3
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• pp.132-147
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• 1989

A total of 83 surface sediments and 55 sea water samples, collected from the southwestern sea of Cheju Island, were analyzed in order to understand their textural characteristics, geochemical composition and the clay mineralogical features. The sediments were subdivided into ten textural classes, namely clayey sand, slightly gravelly muddy sand, sandy clay, clay and mud. The coarse and fine-grained mixed sediments are distributed in the northern part and around the Island, whereas the fine-grained deposits are mainly distributed in the central and southern parts of the study area; small scale mud patches are distributed in the southwestern and northern parts of Cheju Island. The high concentration of total suspended matter in study area gradually increase toward the southwestern and northwestern offshore area. The concentration of geochemical elements is as follow: the content of Mn, Al, Zn, Cr, Cu and Sn increase toward the southern part which is covered mainly with fine-grained deoposits, whereas the content of Ca, Mg and Ag is higher in the northern area; the elements such as Ni, Na, Fe and Pb are more concentrated relatively in muddy deposits rather than in sandy sediments. The light minerals such as Na-Ca feldspars show a high content around the Socotra Rock, toward the Soheugsan and Cheju Islands, but the K-feldspars are relatively high around the Cheju Island. It was noticed that the provenance of these sediments is partly influenced by the geological characteristics near the island. X-ray diffractogram for clay minerals from the southeastern mud patch and around the Soheugsan Island shows the diagnostic calcite peak indicating that the greater part of these clay fraction may have been derived from present and ancient Hwangho River. The high concentration of smectite in the northern part near the Cheju and around the Soheugsan Islands, eastern side of Socotra Rock probably result from supplies smectite altered from volcanic materials distributed in the Cheju Island and Socotra Rock, whereas the samples near the Chuja and northern parts of the Cheju Island contain weak calcite peak and high concentration of kaolinite and chlorite which is closely related to the geolgical characteristics on the adjacenting land area.

• Economic and Environmental Geology
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• v.50 no.5
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• pp.375-387
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• 2017

Amphibolite-hosted Fe-Ti mineralization at the Soyeonpyeong Island, located in central western part of the Korean Peninsula is a typical orthomagmatic Fe-Ti oxide deposit in South Korea. The amphibolite intruded into NW-SE trending Precambrian metasedimentary rocks. Lower amphibolite is characterized by igneous layering, consisting of feldspar-dominant and amphibole-Fe-Ti oxide-dominant layers. The igneous layering shows complicated and/or sharp contact. In contrast, upper amphibolite has a more complicated lithofacies (garnet-bearing, coarser, and schistose), and massive Fe-Ti oxide ore alternates with schistose amphibolite. NS- and EW-trending fault systems lead to redistribute upper amphibolite-hosted Fe-Ti orebody and igneous layering of lower amphibolite, respectively. The whole-rock compositions of amphibolite and Fe-Ti oxide ore reflect their constituent minerals. Amphibolite shows significantly positive Eu anomalies whereas Fe-Ti oxide ore has weak negative Eu anomalies. Plagioclase (Andesine to oligoclase) and Fe-Ti oxide minerals have constant composition regardless of their distribution. Amphibole has a compositionally variable but it doesn't reflect the chemical evolution. Mineral compositions within individual layers and successive layers are relatively constant not showing any stratigraphic evolution. This suggests that there are no successive injections of Fe-rich magma or assimilation with Fe-rich country rocks. Contrasting Eu anomalies between amphibolite and Fe-Ti oxide ore also suggest that extensive plagioclase fractionation during early crystallization stage cause increase in $Fe_2O_3/FeO$ ratio and overall Fe contents in the residual magma. Thus, Fe-rich residual liquids may migrate at the upper amphibolite by filter pressing mechanism and then produce sheeted massive Fe-Ti mineralization during late fractional crystallization.

• The Journal of the Petrological Society of Korea
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• v.9 no.4
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• pp.238-253
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• 2000

In the eastern part of the Euiseong Basin acidic~intermediate volcanic rocks widely distribute on the Cretaceous sedimentary basement. Coeval granitic rocks and dyke rocks intruded into the volcanic rocks. Volcanic stratigraphy of study area are andesite lava, dacitic lapilli tuff, dacitic flow-banded lava, rhyolitic bedded tuff, rhyolitic massive tuff, dacitic massive lava, rhyolitlc welded tuff occur from the lower to the upper strata. $SiO_2$ content of the volcanic rocks range from 51 to 74 wt.%. With the increase of $SiO_2$, the contents of $TiO_2$, $Al_2$$O_3$, MgO, FeOT MnO, CaO, $P_2$$O_{5}$ decrease but those of $K_2$O increase. The contents of $Na_2$O show dispersive variation. This trend is quite sim-ilar to the major oxide variation in the volcanic rocks from the Yucheon sub-basin. The geochemical natures indicate that the volcanic rocks in the study area are discriminated to the island-arc type high K to medium K calc-alkaline rocks. The compositional variation of the volcanic rocks can be explained by the plagioclase fractionation of the volcanic magmas originated from similar source materials. The volcanic stratigraphy seems to have formed by at least two eruptive sequences of andesitic to rhyolitic and dacitic to rhyolitic magmas which underwent crystallization differentiation.

• The Journal of the Petrological Society of Korea
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• v.10 no.2
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• pp.121-131
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• 2001

The combination of geological, structural and satellite image studies is used to make an examination of the Miocene eruptive type in the Eoil Basin, SE Korea. The basin subsided by the NW-SE extension due to NNW dextral shearing during the East Sea opening. Based on geological structures as well as lithofacies and ages of the basin-fills, it is divided into the NE subbasin and the SW subbasin which were abundantly filled with basaltic volcanics and marine sediments without volcanic materials, respectively: Syndeposional synclines and anticlines are characteristically developed in the NE subbasin, which amplitudes decrease away from the adjacent normal faults to make them into a homoclinal structure. The thicker lavas as well as the younger agglomerates and lacustrine sediments, which show circular distributions, are distributed around the axial zones of major synclines. The satellite image shows four remarkable circular structures within the NE subbasin. They are located adjacent to and along the normal faults, and they are laid almost exactly on the axial zones of the synclines as well as on the distribution area of the agglomerates and lacustrine sediments. These facts indicate that the basaltic lava effusion were conducted by the normal faults like a kind of fissure-eruption and its activity was more predominant at the sites in where the synclines are developed. More active effusion of lava became a reason for deeper subsidence to make differential subsidence and syndepositional folding adjacent to and along the normal faults. Hence, we suggest that a nested cauldron structure was formed in the NE subbasin of the Eoil Basin, and that the volcanism made the subbasin to be a lava pond and controlled the process of filling and sedimentation in the subbasin.

• Geophysics and Geophysical Exploration
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• v.3 no.1
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• pp.1-6
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• 2000

The 1 $km^2$ area studied is located in Sukchun-ri, Hwasung-koon, the southern part of Kyeonggi-do. Even though this site has been known as a contaminated area caused by seawater intrusions, geophysical and geochemical surveys have never been carried out at the site to determine the extent of the seawater contamination and to investigate whether the seawater intrusion is in progress. The purpose of this study is to determine the extent of seawater contamination and a preferred channel of the seawater intrusion using geophysical methods such as DC resistivity surveys with Schlumberger array and a dipole-dipole array. In order to determine whether the seawater intrusion is in progress in the area, DC resistivity monitoring with Schlumberger array was performed. According to the resistivity map obtained from the inversion of the resistivity data measured with Schlumberger array, the study area is divided into two districts as relatively lowly resistive (less than 30 ohm-m) and highly resistive (more than 30 ohm-m) areas. The distribution of the lowly resistive area is consistent with the distribution of the layer composed of clay minerals, and the resistivity of this layer decreases slowly as approaching to the old seashore. Hydrogeological analysis shows that the clay layer within a distance of about 200 m from the seashore has been already contaminated by sea-water and its electric conductivity is 8 times higher than that of the sand layer covered by the clay layer. According to the results of the 2-dimensional DC resistivity surveys with a dipole-dipole array, there are two preferred channels of the seawater intrusion in the site, and both the channels are in the NW-SE direction from the old seashore. The lowly resistive zone in the southern channel extends to a depth of 80 m. The DC resistivity monitoring with Schlumberger array was carried out along the preferred channel which has the low resistivity Bone (fracture zone) that extended to a depth of 80 m. The time series of apparent resistivity, measured at a distance of 260 m from the old coast line, fluctuates with a period of 12 hours. From these observations, it can be concluded that the seawater intrusion caused by tidal action is still in progress along the fractured zone interpreted by the DC resistivity surveys with a dipole-dipole array.

• Economic and Environmental Geology
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• v.20 no.4
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• pp.289-303
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• 1987

당(當) 광산(鑛山)은 1936년(年) 금(金), 은(銀) 광종(鑛種)으로 출원(出願)하였다가 1940년(年) 망간을 추가(追加)하여 망간 광산(鑛山)으로 1975년(年)까지 Mn(30~35%) 110,000여(餘)톤을 생산(生産), 국내생산량(國內生産量)의 70%를 점(占)하였고 1976년(年) Mn광상(鑛床) 하부(下部)에 연(鉛), 아연(亞鉛) 유화광(硫化鑛)을 발견(發見), 현재(現在)까지 Pb十Zn=10% 이상(以上) 원광석(原鑛石) 500,000여(餘)톤을 처리(處理), 연정광(鉛精鑛)(Pb : 62%) 37,000여(餘)톤, 아연정광(亞鉛精鑛)(Zn : 46.5%) 37,000여(餘)톤, 유비광정광(硫砒鑛精鑛)(As : 30%) 5,000여(餘)톤을 생산(生産)하였다. 현재(現在) 일처리(日處理) 220톤 선광장(選鑛場)을 일처리(日處理) 400톤 규모(規模)로 증설계획중(增設計劃中)이다. 당(當) 광산(鑛山)에서 현재(現在)까지 시행(施行)한 갱외시추(坑外試錐)는 75개공(個孔) 18,500여(餘)m, 갱내시추(坑內試錐) 750개공(個孔) 40,000여(餘)m 갱도(坑道) 총연장(總延長) 13,000m에 달(達)하며 지표(地表)(623ML)로 부터 수직(垂直) 300m 하부(下部)까지 갱도(坑道)가 개착(開鑿)되어 있다. 당(當) 광산(鑛山)의 지질(地質)은 여러 조사서(調査書)에 의(依)하여 견해(見解) 차이(差異)를 보여주고 있으나 대체(大體)로 다음과 같은 쪽으로 인정되고 있다. 즉(卽) 본지역(本地域) 루층군(累層群)의 층순(層順)을 하위(下位)로 부터 상위(上位)로 향(向)하여 원남층(遠南層)${\rightarrow}$율리통(栗里統)${\rightarrow}$장산규암층(壯山珪岩層)${\rightarrow}$두음리층(斗音里層)${\rightarrow}$장군석회암층(將軍石灰岩層)${\rightarrow}$동수곡층(東水谷層)${\rightarrow}$재산층(才山層)의 순위(順位)로 보며 장산규암층(壯山珪岩層)과 두음리층(斗音里層)을 조선계(朝鮮系)의 양덕통(陽德統)으로, 장군석회암층(將軍石灰岩層)을 대석회암통(大石灰岩統)으로, 동수곡층(東水谷層)과 함탄층(含炭層)인 재산층(才山層)을 평안계(平安系) 지층(地層)으로 대비(對比)한다. 이들은 본지역(本地域) 북(北)쪽에서는 선(先)캠브리아기(紀)의 원남층(遠南層)과 율리통(栗里統)을 불정합(不整合)으로 덮고 남측(南側)에서는 재산층(才山層)과 원남층(遠南層)이 단층접촉(斷層接觸)하고 있다. 이들 지층(地層)의 주향(走向)은 $N60^{\circ}{\sim}80^{\circ}W$, $N60^{\circ}{\sim}80^{\circ}E$이며 경사(傾斜)는 대체(大體)로 $50^{\circ}{\sim}80^{\circ}N$이며 전체적(全體的)으로 역전(逆轉)된 층서(層序)를 보여주는 바 지질구조(地質構造)에 있어서 단사구조(單斜構造)인지 등사(等斜)습곡의 향사(向斜), 또는 등사(等斜)습곡이 배사구조(背斜構造)인지 아직 밝혀지지 않고 있다. 화성암체(火成岩體)는 본지역(本地域) 서측(西側)에 쥬라기(紀) 춘양화강암(春陽花崗岩)이 불규칙(不規則)한 실입(實入) 접촉면(接觸面)을 보여주며 시대미상(時代未詳)(백악기(白堊紀)?)의 거정화강암(巨晶花崗岩), 반화강암(半花崗岩)이 소암주상(小岩株狀)으로 몇 곳 실입(實入)하고 산성(酸性)~중성(中性)의 맥암(脈岩)과 염기성(鹽基性) 안산암질암(安山岩質岩)이 실입(實入)해 있다. 광상(鑛床)은 장군석회암층(將軍石灰岩層)에 배태(胚胎)되어 있는 열수교대(熱水交代) 연(鉛), 아연(亞鉛), 은등(銀等)의 혼합(混合) 유화광상(硫化鑛床)으로 다량(多量)의 Mn분(分)을 수반(隨伴)하며 지표부(地表部)에 Mn광상(鑛床)을 형성(形成)하고 있다. 광상(鑛床)의 형태(形態)는 괴상(塊狀), 각력(角礫)pipe상(狀), 맥상(脈狀)으로 나타난다. 광상(鑛床)의 성인(成因)과 생성시기(生成時期)에 대(對)하여 많은 논란(論難)이 있다. 즉(卽) 열수교대(熱水交代)냐, 접촉교대(接觸交代)냐, 동시퇴적기원(同時堆積起源)이냐, 또는 생성시기(生成時期)가 쥬라기(紀)인지 백악기(白堊紀)인지에 대해 이론(異論)이 있다. 본지역(本地域) 광상(鑛床)은 남본(南本), 100우(右), 북(北), 유비철(硫砒鐵), 동(東), 서(西), 재남(才南), 재동(才東), 110호(號) 등(等)이 지표(地表) Mn로두광화대(露頭鑛化帶)와 관련(關聯) 명명(命名)된 바 전(前)4자(者)는 하부(下部)에서 유화광상(硫化鑛床)이 확인(確認)되었으나 나머지 후자(後者)에서는 아직 하부(下部)에 유화광상(硫化鑛床)이 확인(確認)되지 않고 있으며 남본광상(南本鑛床)으로 부터 남동(南東) 300여(餘)m 지점에 장군석회암층(將軍石灰岩層)과 동수곡층(東水谷層) 경계부(境界部)에 Fe 55~60% 자철광상(磁鐵鑛床)이 확인(確認)된 바 신례미(新禮美) 자철광상(磁鐵鑛床)과 유사성(類似性)이 있는 것 같아 흥미(興味)롭다. 당(當) 광산(鑛山)의 현재(現在)까지의 탐광(探鑛)은 남본광상(南本鑛床) 지표로두(地表露頭)(Mn) 하부(下部)에서 확인(確認)된 연(鉛), 아연(亞鉛), 은(銀) 유화광체(硫化鑛體) 하부(下部)와 전탐(電探)에 의(依)해 확인(確認)된 북광체(北鑛體), 갱도접근중(坑道接近中)에 확인(確認)된 100우광체(右鑛體), 유비철광체(硫砒鐵鑛體) 등(等)의 하부(下部) 탐광(探鑛)을 주(主)로 하고 지표(地表) Mn로두(露頭) 하부(下部)에 대(對)한 시추탐광(試錐探鑛0을 병행(竝行)하고 있으며 시추(試錐)에 의(依)해서 지표(地表)로 부터 790m 하부(下部)(해발(海拔) 200ML)까지 광화대(鑛化帶)가 확인(確認)되었다. 향후(向後) 탐광방침(探鑛方針)을 확고(確固)히 수립(樹立)하기 위(爲)하여는 광상(鑛床)의 성인구명(成因究明)은 물론(勿論) 광상(鑛床)의 배태조건(胚胎條件)에 있어 지질구조규제(地質構造規制)와 화강암(花崗岩)의 실입상(實入狀)과의 관계(關係), 광액(鑛液)의 통로(通路)에 대(對)한 지질구조(地質構造), 모암(母岩)의 화학(化學) 물리적(物理的) 특성(特性)에 대(對)한 연구(硏究) 검토(檢討)가 었어야 하겠다.