• The Journal of the Petrological Society of Korea
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• v.6 no.3
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• pp.185-209
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• 1997

Granitic rocks in the Cheongsan area cosist of three plutons-Baegrog granodiorite, Cheongsan porphyritic granite, and two mica granite. Amphilboles from the Baegrog granodiorite belong to the calcic amphilbole group and show compositional variations from magnesio-hornblende in the core to actinolitic hornblende in the rim. Biotites from the three granites represent intermediate compositions between phlogopite and annite. Muscovites from the two mica granite are considered to be primary muscovite in terms of the occurrence and mineral chemistry. Each granitic rock reveals systematic variation of major oxide contents with $SiO_2$. Major oxide variation trends of the Baegrog granodiorite are fairly different from those of Cheongsan porphyritic granite and two mica granite. The latter two granitic rocks are also different with each other in variation trends for some oxides. Thus three granitic rocks in the Cheongsan area were solidifield from the independent magmas of chemically different, heterogeneous origin. The granitic rocks in the area show calc-alkaline nature. The whole rock geochemistry shows that the Baegrog granodiorite and Cheongsan porphyritic granite belong to metaluminous, I-type granite, whereas the two mica granite to peraluminous, I/S-type granite. The opaque mineral contents and magnetic susceptibility represent that the granitic rocks in the area are ilmenite-series granite, indicating that each magma was solidified under relatively reducing environment. The tectonic environment of the granitic activity in the area seems to have been active continental margin. Alkali feldspar megacryst in the Cheongsan porphyritic granite is considered to be magmatic, judging from the crystal size, shape, arrangement, and distribution pattern of inclusions. The petro-graphical characteristics of the Cheongsan porphyritic granite can be explained by two stage crystallization. Under the smaller degree of undercooling the alkali feldspar megacrysts rapidly grew owing to slow rate of nucleation and fast growth rate. At the larger degree of undercooling the nucleation rate and density drastically increased and the small crystals of the matrix were formed.

• Economic and Environmental Geology
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• v.34 no.1
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• pp.1-12
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• 2001

The crystal structure of biotite-1M from Bancroft, Ontario, was determined by Rietveld refinement method using high-resolution neutron powder diffraction data at -26.3$^{\circ}C$, 2$0^{\circ}C$, 30$0^{\circ}C$, $600^{\circ}C$, 90$0^{\circ}C$. The crystal structure has been refined to a R sub(B) of 5.06%-11.9% and S (Goodness of fitness) of 2.97-3.94. The expansion rate of a, b, c unit cell dimensions with elevated temperature linearly increase to $600^{\circ}C$. The expansivity of the c dimension is $1.61{\times}10^{40}C^{-1}$, while $2.73{\times}10^{50}C^{-1}$ and $5.71{\times}10^{-50}C^{-1}$ for the a and b dimensions, respectively. Thus, the volume increase of the unit cell is dominated by expansion of the c axis as increasing temperature. In contrast to the trend, the expansivity of the dimensions is decreased at 90$0^{\circ}C$. It may be attributed to a change in cation size caused by dehydroxylation-oxidation of $Fe^{2+}$ to $Fe^{3+}$ in vacuum condition at such high temperature. The position of H-proton was determined by the refinement of diffraction pattern at low temperature (-2.63$^{\circ}C$). The position is 0.9103${\AA}$ from the O sub(4) location and located at atomic coordinates (x/a=0.138, y/b=0.5, z/c=0.305) with the OH vector almost normal to plane (001). According to the increase of the temperature, $\alpha$* (tetrahedral rotation angle), $t_{oct}$ (octahedral sheet thickness), mean distance increase except 90$0^{\circ}C$ data. But the trend is less clearly relative to unit cell dimension expansion because the expansion is dominant to the interlayer. Also, ${\Psi}$ (octahedral flattening angle) shows no trends as increasing temperature and it may be because the octahedron (M1, M2) is substituted by Mg and Fe.

• Economic and Environmental Geology
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• v.40 no.1 s.182
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• pp.1-14
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• 2007

The Guemseong mine is located near the southern margin of the Jurassic Jecheon granitoids collectively with the Cambro-Ordovician mixed dolostone-limestone series of the Yeongweol Group, Choseon Supergroup. Here, two spatially distinct types of skarn formation have been observed. The upper transitional skarn is the calcic Mo skarn which has the mineral assemblage of $garnet+hedenbergite+epidote{\pm}wollastonite{\pm}magnetite{\pm}hematite{\pm}amphibole{\pm}chlorite{\pm}vesuvianite$ within the calcite marble. On the other hand, the lower proximal skarn occurs as a discordant magnesian Fe skarn at the contact of Mo-bearing aplitic cupolas with unidirectional solidification texture(UST) within the dolomitic marble. The magnesian Fe skarn has the mineral assemlage $olivine+diopside+magnetite+tremolite+serpentine+talc+chlorite{\pm}phlogopite$. The formation of two different types of skarn and ore mineralization in Geumseong mine have been attributed to multistage and complex metasomatic replacements that ultimately resulted in silicate-oxide-sulfide sequence of metasomatism. An early prograde stage with anhydrous skarn minerals such as olivine, clinopyroxene and/or garnet with magnetite, formed from high temperature (about $500^{\circ}\;to\;400^{\circ}C$) at an environmental condition of low $CO_2$ fugacity ($XCO_2<0.1$) and 0.5 kbar. The later retrograde stage with hydrous silicates such as amphibole, serpentine, phlogopite, epidote and chlorite with molybdenite or hematite, termed from relatively lower temperature (about $400^{\circ}\;to\;300^{\circ}C$).

• Economic and Environmental Geology
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• v.37 no.5
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• pp.477-497
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• 2004

In the Hongseong and Kwangcheon areas, two ultramafic rocks are exposed as isolated bodies in the Precambrian Kyeonggi gneiss complex. The ultramafic rocks extend for several hundred meters to NNE direction and are contact with adjacent metasediments by steeply dipping faults. The rocks are dunite or harzburgite showing dominantly equigranular-mosaic and protogranular textures with a minor amount of porphyroclastic textures. They contain varying amounts of fosteritic olivine (F$o_{0.91-0.93}$), magnesian pyroxene (E$n_{0.89-0.93}$) and tremolitic to magnesian hornblende with minor amounts of spinel, serpentine, chlorite, magnetite, phlogopite and talc. The rocks are in contrast with adjacent gneiss complex or metabasite (amphibole, biotite, plagioclase, alkali-feldspar and quartz). Geochemically, these ultramafic rocks are characterized by high magnesium number (M$g_#$> 0.88) and transitional element (mainly, Ni>1716 ppm, Cr>1789 ppm), low alkali element (e.g. $K_2$O<0.09 wt.%, Na$_2$O<0.19 wt.%) and depletion of incompatible elements. The calculated correlation coefficients showed good positive correlations among the ferrous (e.g. Sc, V, Zn) elements, incompatible elements (e.g. REE), and among SiO$_2$ or $Al_2$O$_3$ with ferrous elements, whereas negative correlations are appeared between Ni and major elements. These results involve increasing of the ferrous- and $Al_2$O$_3$-bearing minerals(e.g. amphibole and mica) with decreasing of Mg-bearing minerals (e.g. olivine) depending on the degree of alteration. Calculated geothermometries and mineral assemblages suggest that the ultramafic rocks have been metamorphosed through the condition from the greenschist to amphibolite facies. Compared with ultramafic rocks elsewhere, it is thought that those of the Hongseong and Kwangcheon areas are derivatives of the depleted sources since they are depleted in incompatible elements including REE abundances. Moreover overall characteristics of the ultramafic rocks are similar to the those of orogenic related Alpine type ultramafic rocks, especially, shallow mantle slab varieties.

• Journal of the Mineralogical Society of Korea
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• v.19 no.1 s.47
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• pp.15-29
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• 2006

Synthetic Mn-tourmalines (tsilaisite) were obtained by hydrothermal synthesis under the condition of 2 Kbar, $375{\sim}700^{\circ}C$, and 50 day-run-time with complete substitution of Mg in dravite by Mn (Mn%=0, 25, 50, 75, and 100%). They are all 6 samples containing Mn-tourmaline with some amounts of albite, spessartine, rhodocrosite, phlogopite etc, showing different synthetic condition of temperature and Mn composition. Synthetic Mn-tourmalines are of site deficiency in X-site ($0.53{\sim}0.68$) more than that of natural ones (approx. $0.2{\sim}0.3$) and show Mn cations occupying Y-site less than expected with initial experiments, leading to failure in synthesis of end-member tsilaisite. Rietveld structural refinements reveal that $R_{wp}$ ($R_{p}/R_{exp}$) is in the range of 13.35 and 18.62%, $R_{B}$ and S (CofF) are $4.85{\sim}6.25%$ (S-18: 8.57%), $1.31{\sim}1.59$ (S-18: 1.81), respectively. Unit cell parameters (space group R3m, z=3) are ${\alpha}=15.8994\;{\AA}$ and $c=7.1846\;{\AA}$ in average (S-18: ${\alpha}=15.9491\;{\AA},\;c=7.1773\;{\AA}$). Average bond lengths of and are $2.67{\sim}2.69\;{\AA}$ (S-18: $2.65\;{\AA}$) and $2.00{\sim}2.02\;{\AA}$ (S-18: $1.96\;{\AA}$), respectively. Ditrigonality (${\delta}$) are in the range of 0.022 and 0.031 (S-18: 0.061), indicating degrading symmetry with increase of Mn content.

• Korean Journal of Soil Science and Fertilizer
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• v.40 no.5
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• pp.418-428
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• 2007

Physical and chemical properties of the aggregate by-products including sludge and crushed dust samples collected from the 21 private companies throughout the country were analyzed to evaluate possible usage of the by-products as artificial soil materials for plantation. The pH of the materials ranged from 8.0 to 11.0. The organic matter content was $2.85g\;kg^{-1}$, and the total nitrogen content and available phosphate content were low as 0.7 percents and $12.98mg\;kg^{-1}$, respectively. Exchangeable $Ca^{2+}$, $Mg^{2+}$, $K^+$, and $Na^+$ were 2.29, 0.47, 0.02 and $0.05cmol\;kg^{-1}$, respectively. Heavy metal contents were lower than the limits regulated by environmental law of Korea. Textural analysis showed that most of the materials were silt loam with low water holding capacity ranged from 0.67 to 7.41 percents, and with low hydraulic conductivity ranged from 0.4 to $2.8m\;s^{-1}$. Mineralogical analysis showed that the aggregate by product materials were mostly composed of silicate, alumina and ferric oxides except calcium oxide dominant materials derived from limestones. The primary minerals were quartz, feldspars and dolomites derived from granite and granitic gneiss materials. Some samples derived from limestone material showed calcite and graphite together with the above minerals. According to the result, it can be concluded that the materials could be used as the artificial soil material for plantation after proper improvement of the physico-chemical properties and fertility.