• 한국광물학회지
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• 제10권2호
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• pp.114-125
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• 1997

The purpose of this study is to clarify the geological occurrence, mineralogical, physico-chemical and thermal properties of the sericite ore which located in Chungha area, Kyungsangbuk-do. The geology of this area are composed mainly of hornfels and some felsite porphyry. The sericitic ore is classified into sericite, sericite-quartz and quartz-sericite ore according to mineral assemblages. Mineral components in sericite ore are mainly sericite with minor quartz, apatite, sphene, zircon, ilmenite, bismuthinite, iron oxide and etc. Sericite-quartz ore are mainly composed of sericite and quartz. Accessary minerals are muscovite, epidote, zircon, sphene, iron oxide and etc. The chemical compositions of K2O, Al2O3, & Ignition loss in sericite and sericite-quartz ore increase than that of the host rock, while the composition of SiO2, Na2O & Fe2O3 decrease. Sericite and sericite-quartz ore are characterized by the specific gravity of 2.35 and 2.44, the pH of 4.36 cP and 2.36 cP respectively. The result of size analyses of sericite ore is 11.3% in grain volume concentration between 12.9 $\mu\textrm{m}$ and 11.1$\mu\textrm{m}$, and 32.3% between 9.6$\mu\textrm{m}$ and 12.9$\mu\textrm{m}$. The thermal expansivity of sericite and sericite-quartz ore show the similar pattern. The sericite ore shows the thermal expansivity of 0.31% at 50$0^{\circ}C$, 0.39~0.75% at 600~1,00$0^{\circ}C$ and 0.74% at 1,10$0^{\circ}C$. The sericite-quartz ore show the thermal expansivity of 0.29% at 50$0^{\circ}C$, 0.36~0.72% at 600~1,000% and 0.71% at 1,10$0^{\circ}C$.

• 자원환경지질
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• 제7권3호
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• pp.87-100
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• 1974

This paper deals with grain size analysis, heavy mineral analysis and trace element analysis of the recent sediments of Han River basin between Cheongpyong, Gyeonggi province and Seoul. For each location the samples are taken at river shoreline, river berm and river dune. The size analysis discloses that the mean values range from $-1.37{\phi}$ to $-1.60{\phi}$, sorting values range from 0.25 to 1.84, skewness values range from -0.44 to 0.51 and kurtosis values range from -0.1 to 1.75. Based on the textural parameters, the dune sand can be distinguished from the shoreline-berm sand. The content of heavy minerals of each sample ranges from 0.04 to 4.7%. The principal heavy minerals are ilmenite, magnetite, leucoxene, garnet, amphibole, pyroxene, kyanite, zircon, monazite, tourmaline, epidote, limonite, and minor minerals are apatite, sillimanite, andalusite and olivine. In general, dune sand samples contain more heavy minerals than the samples of shoreline or berm sand. This suggests that the heavy mineral concentration is affected by wind action more than by any other causes. The content of ilmenite and leucoxene decreases, whereas the content of zircon and epidote increases as it approaches the downstream region. The differences result from the variance of geological occurrences. The emission spectrochemical analysis and colorimetry analysis revealed that the content of Ni and V in the heavy minerals of the study area are higher than those of other stream sediments in Korea. On the other hand the content of Cu, Ph, Zn, Mo, W, P, Mn, Cr, Ag and Sn are lower in the study area. It has been observed also that the contents of all the elements except for Bi are higher in this area than the samples of marine sediments of Yellow Sea.

• Geosciences Journal
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• 제22권6호
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• pp.955-973
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• 2018

Twenty-eight beach sand samples from the shorelines of Aegean islands adjacent to the plutonic rocks of the Atticocycladic zone were analyzed for major and rare earth element (REE) contents. Results are compared with the adjacent plutonic rocks, in order to determine relative enrichments or depletions and assess the potential for REE exploitation. Among the samples, several are significantly enriched in REE, being deposits of heavy minerals and their concentrations are controlled by the sea waves and local winds. These samples contain Th, U and REE rich minerals such as zircon, xenotime and allanite. The available geochemical characteristics were also used to confirm the parent rocks of the beach sands. The heavy fractions (total, total magnetic and total non-magnetic) of the beach sands are very well correlated with the Heavy REE (HREE) concentrations. Among the minerals of the heavy magnetic fraction, allanite seems to control the REE content in the heavy mineral-enriched samples, while from the heavy non-magnetic fraction, zircon controls mainly the HREE fraction. One site from Mykonos and 3 from Naxos could have potential for REE exploitation as they present the highest ${\Sigma}REE$ and HREE contents than other beach sand placers measured in Greece (Kavala, Sithonia, Maronia, Samothraki, NE Chalkidiki).

• 한국광물학회지
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• 제20권4호
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• pp.289-302
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• 2007

전라남도 신안군 자은도의 둔장해수욕장 해변으로부터 채취한 해빈사로부터 중광물 회수공정을 실시하여, 중광물의 특징 및 회수 가능성에 대한 연구를 수행하였다. 채취 시료는 깊이별로 상부, 중부 및 하부시료로 구분한 뒤 각각에 대하여 spiral separation을 실시하여 얻은 중광물군을 초기물질로 3차에 걸친 중광물 선별작업을 실시하였다. 본 역에서 배태되어 있는 중광물로 티탄철석, 저어콘, 금홍석, 아나타제, 모나자이트 및 제노타임 등이 관찰되었다. 3차에 걸친 Table separation을 실시한 결과, 맥석광물인 석영, 정장석, 알바이트 및 백운모가 여전히 존재하였다. 따라서 부가적으로 비중선별이 추가적으로 요구된다. 수선을 통한 중광물의 선별을 실시한 결과, 각 중광물의 다양한 원마도 및 색깔을 보임으로써, 배태된 중광물들이 다양한 성인에 의해 형성되었음을 시사하고 있다.

• 암석학회지
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• 제16권3호
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• pp.180-188
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• 2007

경기육괴 북서 연변부에 분포하는 감악산 알칼리 변성화강암질암(GAM)에 대한 CHIME 저어콘 연대 측정을 실시하여 $247{\pm}14Ma$(n=103, MSWD=0.92)의 광역변성작용 연대를 구하였다. 이 연대는 임진강대에서 보고된 광역변성작용의 시기와 일치하며, 또한 중국의 페름기-트라이아스기 대륙충돌관련 고압 내지 초고압 광역변성작용 시기와도 일치한다. GAM을 변형시킨 경기전단대의 연성전단작용이 226 Ma에 $500^{\circ}C$의 조건에 형성되었고(Kim et al., 2000) 이를 부정합으로 피복하는 대동층군의 퇴적시기가 트라이아스기 후기 내지 쥬라기 초기인 점을 감안하면 이 기간 동안 GMA의 냉각속도는 $18{\sim}10^{\circ}C/Ma$이다. 또한 저어콘이 상부 각 섬암상의 온도조건인 $700^{\circ}C$ 이상에서 재성장하기 시작하는 것을 고려하면 GAM의 최고 변성시기인 247 Ma부터 쥬라기 초기까지 GAM의 냉각속도는 최소 $10^{\circ}C/Ma$가 된다. 이러한 빠른 냉각속도는 중국 다비-술루 대륙충돌대에서 관찰되는 섭입지각의 융기에 따른 냉각속도와 유사하다. 따라서 적어도 경기육괴 북서부 지역은 중국 대륙충돌대와 유사한 동시기 변성조산대에 대비될 수 있음을 지시한다.

• 자원환경지질
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• 제53권4호
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• pp.397-411
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• 2020

백악기 유천층군은 후기 백악기 화산암 및 퇴적암으로 구성되며, 경상화산호의 화산활동에 의해 형성되었다. 유천층군 전반에 대한 정밀한 야외조사의 부재는 유천층군의 형성시기와 화산호의 시·공간적 발달양상에 대한 이해의 부재로 귀결되었다. 이번 연구에서는 현풍-부곡 지역에 나타나는 하양층군 최상부인 진동층과 유천층군 최하부의 경계에 대한 지질도를 작성하고 SHRIMP U-Pb 저어콘 연대를 통해 유천층군 형성시기를 규명하였다. 연구지역의 유천층군은 진동층을 정합으로 피복하고 있는 응회암 및 화산력응회암으로 구성되며, 폭발적인 화산분출에 의한 화쇄밀도류에 의해 퇴적되었다. 이들 응회암의 SHRIMP U-Pb 저어콘 연대는 약 96-97 Ma를 보여주며 이는 연구지역 진동층의 퇴적이 약 96-97 Ma에 경상화산호의 폭발적인 화산활동에 의해 종료되었음을 지시한다. 이 연대 범위는 경주지역 의성소분지 남부의 유천층군 최하부 퇴적연대(88-85 Ma)와 차이를 보이는데 이는 유천층군을 형성한 화산활동 및 그 영향 범위가 화산호로부터의 거리 혹은 경상화산호로부터 퇴적물을 공급하는 고수계 발달양상의 차이에 의한 것으로 추정된다.

• 자원환경지질
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• 제56권6호
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• pp.817-830
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• 2023

This study investigates the age of the surficial rocks in the Arunta region using Uranium-Lead (U-Pb) geochronological dating. Rock samples were collected at four locations, Cattle-Water Pass (CP 1610), Gough Dam (GD 1622 and GD 1610), and London-Eye (LE 1601), within the Strangways Metamorphic Complex and crushed by selFragging. Subsequently, the zircon grains were imaged using Cathodoluminescence (CL) analysis and the U-Pb (uranium and lead) isotope ratios and the chrono-stratigraphy were measured. The imaged zircon revealed an anomalous heterogeneous crystal structure. Ellipses of the samples at locations GD1601, CP1610, and GD1622 fall below the intercept indicating the ages produced discordant patterns, whereas LE1601 intersects the Concordia curve at two points, implying the occurrence of an event of significant impact. For the rock sample at CP1610, the estimated mean age is 1742.2 ± 9.2 Ma with mean squared weighted deviation (MSWD) = 0.49 and probability of equivalence of 0.90; 1748 ± 15 Ma - MSWD = 1.02 and probability of equivalence of 0.40 for GD1622; and 1784.4 ± 9.1 Ma with MSWD of 1.09 and probability of equivalence of 0.37 for LE1601. But for samples at GD1601, two different age groups with different means occurred: 1) below the global mean (1792.2 ± 32 Ma) estimated at 1738.2 ± 14 Ma with MSWD of 0.109 and probability of equivalence of 0.95 and 2) above it with mean of 1838.22 ± 14 Ma, MSWD of 1.6 and probability of equivalence of 0.95. Analysis of the zircon grains has shown a discrepancy in the age range between 1700 Ma and 1800 Ma compared to the ASO dated to have occurred between 440 and 300 Ma. Moreover, apparent similarity in age of the core and rim means that the mineral crystallized relatively quickly without significant interruptions and effect on the isotopic system. This may have constraint the timing and extent of geological events that might have affected the mineral, such as metamorphism or hydrothermal alteration.

• 자원환경지질
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• 제31권1호
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• pp.69-84
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• 1998

A geochemical study was carried out to define how marine shore sediments are related to their terrestrial source rocks in the region of Taean and Byunsan Peninsula, western Korea. The lithology of the coastal part of the study area is composed of Pre-Cambrian granite gneiss, schist, Jurassic terrestrial sedimentary rocks, and Cretaceous plutonic intrusives. Shore sediments are transported from three drainage tributaries. The sediments consist of quatrz with clay minerals, such as illite, kaolinite, smectite, chlorite. Heavy minerals include hematite, ilmenite, rare amount of zircon and apatite. Compared to those in coastal rocks, amount of heavy minerals in the sediments is considerably low. The low content of heavy minerals is thought to be attributed to the heavy mineral detainment in the river beds and influences of tidal currents which cause heavy minerals to accumulate in specific spots. Chemical composition of the major and trace elements, trace elements, and REE chondrite normalized pattern suggest that shore sediments transported from the corresponding drainage tributary show close mineralogical and geochemical relationships with the source rocks distributed in the Taean and Byunsan Peninsula.

• 자원환경지질
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• 제27권1호
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• pp.11-28
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• 1994

The Anyang Feldspar Mine is located in Seoksu Dong, Anyang City, Kyeonggi Do, Korea and has a long exploitation record that is once produced high grade sodium feldspars, for glaze. Geologically, This area is mainly composed of Mesozoic Jurassic biotite granite (Anyang granite) which intruded Precambrian Kyeonggi Gneiss Complex outcroped near the mining area. The deposit is localized on the southwest hill side of Anyang granite batholith and is confined in hydrothemal alteration zone formed by sodium-rich alkali hydrothermal fluids along the fractures of leucocratic granite showing later differentiation facies in the biotite granite. The hydrothermal alteration is characterized by albitization, sericitization, and desilication. The microscopic observation and EPMA, XRD analysis of the feldspar ores show that major minerals are albite and quartz and accessory minerals are orthoclase and sericite, and they are rarely associated with perthite, fluorite, zircon, kaolinite, molybdenite, microcline and iron-oxide. In the REE pattern, the strong negative Eu anomalies of the feldspar ores indicate the influence of feldspar fractionation and show similiar pattern of the host leucocratic granite. The filling temperature of quartz crystals in ore zone ranges from $276^{\circ}C$ to $342^{\circ}C$, and it is inferred that the alteration occurred by the hypothermal solution.

• 자원환경지질
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• 제15권3호
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• pp.113-122
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• 1982

The surveyed Boseong river, flows from south to north crossing Boseong gun Mirukg myon, Nodong myon, Yuleo myon, Bocgnae myon, Mundeog myon, and Seungju gun Nam myon, Jeonranam do. The geology of the surveyed area consists of age-unknown composite gneiss and schist, crystaline chlorite gneiss, porphyroblastic gneiss and granite gneiss, and metasediments of Myon Bong formation and Seologri formation. These metamorphic rocks are intruded by cretaceous biotite granite, granodiorite, and quartz diorite. The heavy sands occur in Quarternary alluvium and colluvium. The composition of the river bed is sand 60%, gravel 30%, and clay 10%. The gravel content of the river bed decreases as the increases. The average depth of auger boring is 0.87 m. The average heavy mineral composition of the heavy sand is monazite 6.83%, zircon 4.88%, ilmenite 11.36%, magnetite 8.36% and garnet 4.84%. The best heavy minerals separation procedure would be primary treatment of the sand by humphrey spiral and table, and retreatment of the table concentrate by magnetic separator. The minimum economically feasible capacity of gravity and magnetic separation plant would be 500 ton/hr when only the heavy minerals are recovered but it may be reduced to 100 ton/hr. capacity, if gravels and sands are added to the valuable products.