• The Journal of the Petrological Society of Korea
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• v.22 no.2
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• pp.137-151
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• 2013

This study is focused on element behaviors and mineral compositions of the fault rock developed in Yongdang-ri, Yangbuk-myeon, Gyeongju City, Korea, using XRF, ICP, XRD, and EPMA/BSE in order to better understand the chemical variations in fault rocks during the fault activity, with emphasis on dependence of chemical mobility on mineralogy across the fault zone. As one of the main components of the fault rocks, $SiO_2$ shows the highest content which ranges from 61.6 to 71.0%, and $Al_2O_3$ is also high as having the 10.8~15.8% range. Alkali elements such as $Na_2O$ and $K_2O$ are in the range of 0.22~4.63% and 2.02~4.89%, respectively, and $Fe_2O_3$ is 3.80~12.5%, indicating that there are significant variations within the fault rock. Based on the chemical characteristics in the fault rocks, it is evident that the fault gouge zone is depleted in $Na_2O$, $Al_2O_3$, $K_2O$, $SiO_2$, CaO, Ba and Sr, whereas enriched in $Fe_2O_3$, MgO, MnO, Zr, Hf and Rb relative to the fault breccia zone. Such chemical behaviors are closely related to the difference in the mineral compositions between breccia and gouge zones because the breccia zone consists of the rock-forming minerals including quartz and feldspar, whereas the gouge zone consists of abundant clay minerals such as illite and chlorite. The alteration of the primary minerals leading to the formation of the clay minerals in the fault zone was affected by the hydrothermal fluids involved in fault activity. Taking into account the fact that major, trace and rare earth elements were leached out from the precursor minerals, it is assumed that the element mobility was high during the first stage of the fault activity because the fracture zone is interpreted to have acted as a path of hydrothermal fluids. Moving toward the later stage of fault activity, the center of the fracture zone was transformed into the gouge zone during which the permeability in the fault zone gradually decreased with the formation of clay minerals. Consequently, elements were effectively constrained in the gouge zone mostly filled with authigenic minerals including clay minerals, characterized by the low element mobility.

• Economic and Environmental Geology
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• v.45 no.6
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• pp.643-659
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• 2012

The Chungju Fe-REE deposit is located in the Kyemyeongsan Formation of the Ogcheon Group. The Kyemyeongsan Formation includes meta-volcanic rocks and pegmatite hosted REE deposit which show different kind of REE-containing minerals. The meta-volcanic rocks hosted REE deposits' main REE minerals are allanite, zircon, apatite, and sphene, whereas the pegmatite hosted REE deposits is mainly composed of fergusonite, and karnasurtite, zircon, thorite. The meta-volcanic rock hosted major REE mineral is allanite as the form of aggregation and contains 23.89-29.19 wt% TREO (Total Rare Earth Oxide), 4.71-9.92 wt% $La_2O_3$, 11.30-14.33 wt% $Ce_2O_3$, 0.11-0.29 wt% $Y_2O_3$, 0.15-0.94 wt% $ThO_2$, as a formula of (Ca, Y, REE, Th)$_{2.095}$(Mg, Al, Ti, Mn, $Fe^{3+})_{2.770}(SiO_4)_{2.975}(OH)$. Accompanying REE in a coupled substitution for $Ca^{2+}$ (M1 site) and $Al^{3+}-Fe^{2+}$ (M2 site) leads to a large chemical variety. Due to the allanite's high contents of Fe, it belongs to Ferrialanite. The pegmatite hosted deposit's domi-nant REE mineral is fergusonite as prismatic or subhedral grains associated with zircon, fluorite and karnasurtite. Geochemical composition of the fergusonite($YNbO_4$) suggests substitution of Y-REE and Y-Th in A-site, and Nb-Ta-Ti in B-site, furthermore the proportion of $Y_2O_3$ and $Nb_2O_5$ is oddly 1:1.5 comparing to the ideal ratio 1:1 and Nb is higher than Y, also A-site Y actively substitutes with REE. Karnasurtite in pegmatite variously ranges 9.16-22.88 wt% $Ce_2O_3$, 2.15-9.16 wt% and $La_2O_3$, 0.44-10.8 wt% $ThO_2$, as a calculated formula (Y, REE, Th, K, Na, Ca)$_{1.478}(Ti, Nb)_{1.304}$(Mg, Al, Mn, $Fe^{3+})_{0.988}$(Si, P)$_{1.431}O_7(OH)_4{\cdot}3H_2O$. Firstly the 870-860 Ma is the initial age of the supercontinent Rhodinia dispersal and subsequent A-1 type volcanism, which contains Fe, REE, and HFS(High Field Strength elements; Nb, Zr, Y etc.) elements in Fe-rich meta-volcanic rocks dominant Kyemyeongsan Formation, might mineralized allanite. Another synthesis is that regional metamorphism at late Paleozoic 300-280 Ma(Cho et al., 2002) might cause allanite mineralization. Also pegmatite REE mineralization highly related to the granite intrusion over the Chungju area in Jurassic(190 Ma; Koh et al., 2012). Otherwise above all, A-1 type volcanism at the same time of the Kyemyeongsan Formation development, regional metamorphism and pegmatite, might have caused REE mineralization. Although REE ore bodies display a close spatial association, each ore bodies display temporal distinction, different mineral assemblage and environment of ore formation.

• Economic and Environmental Geology
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• v.30 no.5
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• pp.417-431
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• 1997

Characteristics of sedimentary rocks and enrichment of toxic elements in shale and coal from the Chungnam coal field were investigated based upon geochemistry of major, trace and rare earth elements. Shale and coal of the area are interbedded along the Traissic to the Jurassic Daedong Supergroup, which can be subdivided into grey shale, black shale and coal. The coal had been mined, however all the mines are abandonded due to the economic problems. The shale and coal are characterized by relatively low contents of $SiO_2$, and $Al_2O_3$ and high levels of loss-on-ignition (LOI), CaO and $Na_2O$ in comparison with the North American Shale Composite (NASC). Light rare earth elements (La, Ce, Yb and Lu) are highly enriched with the coal. Ratios of $Al_2O_3/Na_2O$ and $K_2O/Na_2O$ in shale and coal range from 30.0 to 351.8 and from 4.2 to 106.8, which have partly negative correlations against $SiO_2/Al_2O_3$ (1.24 to 6.06), respectively. Those are suggested that controls of mineral compositions in shale and coal can be due to substitution and migration of those elements by diagenesis and metamorphism. Shale and coal of the area may be deposited in terrestrial basin deduced from high C/S (39 to 895) and variable composition of organic carbon (0.39 to 18.40 wt.%) and low contents of reduced sulfur (0.01 to 0.05 wt.%). These shale and coal were originated from the high grade metamorphic and/or igneous rocks, and the rare earth elements of those rocks are slightly influenced with diagenesis and metamorphism on the basis of $Al_2O_3$ versus La, La against Ce, Zr versus Yb, the ratios of La/Ce (0.38 to 0.85) and Th/U (3.6 to 14.6). Characteristics of trace and rare earth elements as Co/Th (0.07 to 0.86), La/Sc (0.31 to 11.05), Se/Th (0.28 to 1.06), V/Ni (1.14 to 3.97), Cr/V (1.4 to 28.3), Ni/Co (2.12 to 8.00) and Zr/Hf (22.6~45.1) in the shale and coal argue for inefficient mixing of the simple source lithologies during sedimentation. These rocks also show much variation in $La_N/Yb_N$ (1.36 to 21.68), Th/Yb (3.5 to 20.0) and La/Th (0.31 to 7.89), and their origin is explained by derivation from a mixture of mainly acidic igneous and metamorphic rocks. Average concentrations in the shale and coal are As=7.2 and 7.5, Ba=913 and 974, Cr=500 and 145, Cu=20 and 26, Ni=38 and 35, Pb=30 and 36, and Zn=77 and 92 ppm, respectively, which are similar to those in the NASC. Average enrichment indices for major elements in the shale (0.79) and coal (0.77) are lower than those in the NASC. In addition, average enrichment index for rare earth elements in coal (2.39) is enriched rather than the shale (1.55). On the basis of the NASC, concentrations of minor and/or environmental toxic elements in the shale and coal were depleted of all the elements examined, excepting Cr, Pb, Rb and Th. Average enrichment indices of trace and/or potentially toxic elements (As, Cr, Cu, Ni, Pb, U and Zn) are 1.23 to 1.24 for shale and 1.06 to 1.22 for coal, respectively.

• Journal of the Korean Ceramic Society
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• v.43 no.6 s.289
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• pp.369-375
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• 2006

[ $(Ba_{0.5}Sr_{0.5})_{0.99}Co_{x}Fe_{1-x}O_{3-{\delta}}$ ] [x=0.8, 0.2](BSCF) powders were synthesized by a Glycine-Nitrate Process (GNP) and the electrochemical performance of the BSCF cathode on a scandia stabilized zirconia, $[(Sc_{2}O_3)_{0.11}(ZrO_2)_{0.89}]-1Al_{2}O_3$ was investigated. In order to prevent unfavorable solid-state reactions between the cathode and zirconia electrolyte, a GDC ($Gd_{0.1}Ce_{0.9}O_{2-{delta}}$) buffer layer was applied on ScSZ. The BSCF (x = 0.8) cathode formed on GDC(Buffer)/ScSZ(Disk) showed poor electrochemical property, because the BSCF cathode layer peeled off after the heat-treatment. On the other hand, there were no delamination or peel off between the BSCF and GDC buffer layer, and the BSCF (x = 0.2) cathode exhibited fairly good electrochemical performances. It was considered that the observed phenomenon was associated with the thermal expansion mismatch between the cathode and buffer layer. The ohmic resistance of the double layer cathode was slightly lower than that of the single layer BSCF cathode due to the incorporation of platinum particle into the BSCF second layer.

• Economic and Environmental Geology
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• v.26 no.4
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• pp.489-498
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• 1993

The Okbang amphibolites occurring as sill-shaped bodies within the Precambrian Wonnam Group have been studied in terms of geochemical characteristics for their tectonomagmatic environments. The amphibolites fall in the ortho-amphibolite fields in Ni and Cr versus Cu diagrams. They belong to subalkaline and tholeiitic series in total alkali versus silica and ternary AFM diagrams, respectively. They show the compositional variation corresponding to the differentiation trend of tholeiitic suites. In discrimination diagrams using high-field-strength elements such as Ti, Zr, Nb and Y, the amphibolites show geochemical affinities to both of volcanic-arc tholeiites and normal (depleted) mid-oceanic ridge tholeiites. The REE patterns of the amphibolites are nearly flat and extremely similar to those of back-arc tholeiites. $(La/Yb)_{CN}$ ratios vary from 0.89 to 2.02 with an average value of 1.23. Such low light-REE abundances in the amphibolites suggest that they were derived from the upper mantle source depleted in these elements. In view of geochemical characteristics showing strong enrichments of incompatible elements such as K and Rb, distinctive negative Nb anomalies, depletions of light-REE observed also in normal (depleted) mid-oceanic ridge tholeiites, and unfractionated immobile elements such as Y and Yb, the tholeiitic magmas, from which the parent rocks of the amphibolites were formed, would be generated from a depleted upper mantle source and contaminated by continental crustal materials en route to surface. Tectonomagmatic environment for the amphibolites can be assumed to be continental back-arc basin.

• Journal of the Korean Ceramic Society
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• v.48 no.2
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• pp.127-133
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• 2011

Non-Alkali multicomponent $La_2O_3-Al_2O_3-SiO_2$ glasses has been designed and analyzed on the basis of a mixture design experiment with constraints. Fitted models for thermal expansion coefficient, glass transition temperature, Young's modulus, Shear modulus and density are as follows: ${\alpha}(/^{\circ}C)=8.41{\times}10^{-8}x_1+5.72{\times}10^{-7}x_2+2.13{\times}10^{-7}x_3+1.09{\times}10^{-7}x_4+1.10{\times}10^{-7}x_5+1.15{\times}10^{-7}x_6+2.72{\times}10^{-8}x_7+2.41{\times}10^{-7}x_8-1.08{\times}10^{-8}x_1x_2+4.28{\times}10^{-8}x_3x_7-2.02{\times}10^{-8}x_3x_8-1.60{\times}10^{-8}x_4x_5-2.71{\times}10^{-9}x_4x_8-2.19{\times}10^{-8}x_5x_6-3.89{\times}10^{-8}x_5x_7$ $T_g(^{\circ}C)=7.36x_1+15.35x_2+20.14x_3+8.97x_4+13.85x_5+4.22x_6+28.21x_7-1.44x_8-0.84x_2x_3-0.45x_2x_5-1.64x_2x_7+0.93x_3x_8-1.04x_5x_8-0.48x_6x_8$ $E(GPa)=2.04x_1+14.26x_2-1.22x_3-0.80x_4-2.26x_5-1.67x_6-1.27x_7+3.63x_8-0.24x_1x_2-0.07x_2x_8+0.14x_3x_6-0.68x_3x_8+0.29x_4x_5+1.28x_5x_8$ $G(GPa)=0.35x_1+1.78x_2+1.35x_3+1.87x_4+9.72x_5+29.16x_6-0.99x_7+3.60x_8-0.48x_1x_6-0.50x_2x_5+0.08x_3x_7-0.66x_3x_8+0.94x_5x_8$ ${\rho}(g/cm^3)=0.09x_1+0.51x_2-4.94{\times}10^{-3}x_3-0.03x_4+0.45x_5-0.07x_6-0.10x_7+0.07x_8-9.60{\times}10^{-3}x_1x_2-8.20{\times}10^{-3}x_1x_5+2.17{\times}10^{-3}x_3x_7-0.03x_3x_8+0.05x_5x_8$ The optimal glass composition similar to the thermal expansion coefficient of Si based on these fitted models is $65.53SiO_2{\cdot}25.00Al_2O_3{\cdot}5.00La_2O_3{\cdot}2.07ZrO_2{\cdot}0.70MgO{\cdot}1.70SrO$.

• The Journal of the Petrological Society of Korea
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• v.6 no.1
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• pp.19-33
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• 1997

This study reports the results about the petrography and geochemical characteristics of 10 representative volacanic rocks. The Cretaceous volcanic rocks distributed in the vicinity of the Kageo island composed of andesitic rocks, dacitic welded tuff, and rhyolitic rocks in ascending order. Sedimentary rock is the basement in the study area covered with volcanic rocks. Andesitic rocks composed of pyroclastic volcanic breccia, lithic lapilli tuff and cryptocrystallin lava-flow. Most dacitic rocks are lapilli ash-flow welded tuff. Rhyolitic rocks consists of rhyolite tuff and rhyolite lava flow. Rhyolite tuff are lithic crystal ash-flow tuff and crystal vitric ash-flow tuff with somewhat accidental fragments of andesitic rocks, but dacitic rocks. The variation of major and trace element of the volcanic rocks show that contents of $Al_2O_3$, FeO, CaO, MgO, $TiO_2$ decrease with increasing of $SiO_2$. On the basis of Variation diagrams such as $Al_2O_3$ vs. CaO, Th/Yb vs. Ta/Yb, and $Ce_N/YB_N$ vs. $Ce_N$, these rocks represent mainly differentiation trend of calc-alkaline rock series. On the discriminant diagrams such as Ba/La and La/Th ratio, Rb vs. Y + Nb, the volcanic rocks in study area belongs to high-K Orogenic suites, with abundances of trace element and ternary diagram of K, Na, Ca. According to the tectonic discriminant diagram by Wood, these rocks falls into the diestructructive continental margin. K-Ar ages of whole rocks are from andesite to rhyolite $97.0{\pm}6.8~94.5{\pm}6.6,\68.9{\pm}4.8,\61.5{\pm}4.9~60.7{\pm}4.2$ Ma, repectively. Volcanic rocks in study area show well correlation to the Yucheon Group in terms of rock age dating and geochemcial data, and derived from andesitic calc-alkaline magma that undergone low pressure fractional crystallization dominated plagioclase at <30km.