• The Journal of the Petrological Society of Korea
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• v.11 no.2
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• pp.65-73
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• 2002

The wavy extinction of quartz grains can be used as a good indicator to show the degree of rock deformation. To determine degree of the rock deformation, intensity of wavy extinction (IWE) of quartz grains was measured by using polarizing microscope, digital camera, and NIH image (or Scion Image). In this experiment, the measurement was performed along the line perpendicular to the subgrain boundary of wavy extinction. IWE was measured when a quartz grain shows maximum extinction in polarizing microscope. NIH image was represented in terms of 256 gray-scale brightness, which was associated with intensity of the wavy extinction. IWE was determined by the degree of brightness versus the measuring length of a quartz grain. IWE was analysed in the distribution chart with the collection unit of 5. Regarding the characteristics of data distribution, the median between the mode and the median of the histogram is defined as a representative value for the IWE, and this value is subdivided into the five levels of rock deformation zones (lowest- or non-, low-, medium-, high-, and highest deformation) with their respective indices (D1, D2, D3, D4, and D5). The correlation between the Eonyang Granite and the Yangsan Fault was investigated by using the indices. The results indicate that IWE values decreased away from the fault.

• Journal of the Mineralogical Society of Korea
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• v.1 no.2
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• pp.83-93
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• 1988

Amethysts in Eonyang Granite of Woolju-Kun, Kyungnam Province are frequently parallelly grown on top of preexisting smoky quartz crystallized on milky and colorless quartz crystals, which, as a whole, resemble "mushroom" in outer appearance. Fluid inclusions in the amethysts may be grouped into (1) gaseous inclusions (G>L), (2) liquid inclusions (L>G), (3) $L_{CO_2}$-bearing inclusions (L+G+$L_{CO_2}$), (4) halite-bearing inclusions (L+G+halite), (5) multiphase inclusions (L+G+halite+sylvite${\pm}$opaque mineral). In addition, euhedral K-feldspars and acicular hematite crystals are included in colorless-milky quartz and deep purple-red quartz, respectively. Filling temperatures of each type of fluid inclusions were measured as follows: $320{\sim}560^{\circ}C$ for gaseous inclusions; $100{\sim}290^{\circ}C$ for liquid inclusions; $200{\sim}310^{\circ}C$ for $L_{CO_2}$-bearing inclusions; $300{\sim}430^{\circ}C$ for halite-bearing inclusions; and $370{\sim}430^{\circ}C$ for polyphase inclusions. The finished-gem amethysts from Eonyang may be distinguished from Brazilian amethysts by the difference in filling degree of gaseous inclusions by the presence of hematite aciculae, and of $L_{CO_2}$-bearing inclusions, and also by the absence of Zebra-striation structure. They may also be differentiated from synthetic amethysts by presence of straight color banding, solid inclusions, and $L_{CO_2}$-bearing inclusions which are not found in synthetic materials.

• Economic and Environmental Geology
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• v.25 no.4
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• pp.463-477
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• 1992

The study area consists of sedimentary and volcanic rocks of Gyeongsang Supergroup, granitoid intrusives, and hornfelses around the granitoids. Granitoid intrusives occur in small stocks in Nijeon-ri, Uggogri, and Yul-ri area. The masses in Nijeon-ri and Uggog-ri are hornblende-biotite granodiorite, biotite granodiorite respectively, and Yul-ri mass is biotite granite. Surrounding sediments of these masses were thermally metamorphosed and contact aureoles were formed. The studied granitoids are considered to be formed by sequential crystallization-differentiation from calc-alkalic granitoid magma. Metamorphic minerals occurring in contact aureole are chlorite, actinolite, epidote, and biotite. Diopside and hornblende are observed in small amount in some lithology around contact aureole. The lithology of contact aureole is predominantly silty and sandy, and characteristic metamorphic minerals were poorly developed because of low temperature metamorphism. Low temperature in contact aureole could be deduced from the facts that the intrusions were small size, shallow depth, low temperature, and rare movement of volatiles from magma.

• Economic and Environmental Geology
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• v.26 no.2
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• pp.167-174
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• 1993

Limited geochemical components have been detected in fluid inclusions from ore deposits in south Korea by non-destructive and destructive analytical methods. Review of fluid inclusion studies display that the homogenization temperatures and salinities are in direct proportion. W and Cu ore deposits tend to show higher homogenization temperatures and salinities than Au ore deposits. Abundant halite-bearing fluid inclusions from the Eonyang Granite producing precious amethyst crystals may indicate that the initial fluid originated from magma is highly saline as shown by the quartz from the granite. Raman Laser microprobe detected $CO_2$, $N_2$ and $CH_4$ in a gold deposit, while these components are hardly detected from other deposits, even though destrucive analysis has dectected $CO_2$, $N_2$, $CH_4$, $H_2S$, and $SO_2$ from most of ore deposits. Individual fluid inclusion shows quite different components. These results suggest that large numbers of fluid inclusions should be analysed by Raman Laser microprobe to gain reliable data. Halite-bearing inclusion is hardly found in fluid inclusions from epithermal gold deposits in south Korea. Geochemistry, homogeinzation temperature and salinity of fluid inclusions may be useful to apply for exploration to find a concealed orebody.

• Journal of the Mineralogical Society of Korea
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• v.22 no.3
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• pp.207-216
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• 2009

Three distinct types of fluid inclusions in amethyst and quartz crystals are associated with metamorphic events in the Korea Amethyst deposit from Uljin-Gun, Gyeongbuk Province. The amethyst displays bimodal grain size distribution in fine-grained, strain-free equigranular quartz with coarse-grained quartz grains with kink bands and undulose extinction. Type I inclusions are liquid-rich and salinity is 0~7 wt% NaCl and the homogenization temperatures ($T_h$) $91{\sim}231^{\circ}C$ with eutectic temperatures ($T_e$) $-52{\sim}-20^{\circ}C$. Type II inclusions are vapor-rich (80~90 vol%). The salinity and $T_h$ ranges 3~6 wt% NaCl and $230{\sim}278^{\circ}C$, respectively with $T_e$ $-56{\sim}-23^{\circ}C$. Type III inclusions contain a daughter mineral other than NaCl. The salinity ranges 32~36 wt% NaCl and $T_h$ $210{\sim}271^{\circ}C$. The textural and fluid inclusion evidences suggest that the host Buncheon granite gneiss and Amethyst pegmatite experienced dynamic recrystallization and the studied fluid inclusions are metamorphic in origin. The metamorphic event possibly occurred at higher temperature than $271{\sim}278^{\circ}C$. The amethysts from Uljin Korea Amethyst can be distinguished from the synthetic amethyst on basis of the distinctive two and three-phases fluid inclusions. Furthermore, it is noticeable that Korea amethyst do not contain NaCl-bearing and $CO_2$-rich fluid inclusions unlike those compared to those from Eonyang and Samcheonpo deposits related to unmetamorphosed granitic rocks.