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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
Economic and Environmental Geology
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Journal DOI :
The Korean Society of Economic and Environmental Geology
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Volume & Issues
Volume 34, Issue 6 - Dec 2001
Volume 34, Issue 5 - Oct 2001
Volume 34, Issue 4 - Aug 2001
Volume 34, Issue 3 - Jun 2001
Volume 34, Issue 2 - Apr 2001
Volume 34, Issue 1 - Feb 2001
Selecting the target year
Rietveld Structure Refinement of Biotite Using Neutron Powder Diffraction
Economic and Environmental Geology, volume 34, issue 1, 2001, Pages 1~12
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
. 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
. The expansivity of the c dimension is
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
. It may be attributed to a change in cation size caused by dehydroxylation-oxidation of
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
). The position is 0.9103
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,
* (tetrahedral rotation angle),
(octahedral sheet thickness), mean distance increase except 90
data. But the trend is less clearly relative to unit cell dimension expansion because the expansion is dominant to the interlayer. Also,
(octahedral flattening angle) shows no trends as increasing temperature and it may be because the octahedron (M1, M2) is substituted by Mg and Fe.
Mineral Chemistry and Geochemistry of the Bentonites Intercalated within the Basal Conglomerates of the Tertiary Sediments in Korea and Their Stratigraphical Implication
Economic and Environmental Geology, volume 34, issue 1, 2001, Pages 13~23
Bentonite layers are intercalated within the basal conglomerates in the Tertiary sedimentary basins of Kampo, Janggi and Pohang, southeastern Korea. Eighteen samples of the bentonites went through X-ray diffraction, scanning electron microscopy, heavy mineral analyses, chemical analyses and oxygen, hydrogen stable isotope analyses to define the mineralogical characters of the bentonites. Heavy minerals such as zircons, apatites, amphiboles and biotites separated from bentonites show clean and euhedral surfaces, which are the characteristic features of volcanic origin. But biotites from the Chunbook Conglomerate are found as altered and heavily broken flakes which implies longer transportation of these bentonites.
ratios of <2
m particle fractions (the Chunbook Conglomerate 0.031; Janggi 0.029; Kampo 0.025) suggest that those are originated from volcanic tuffs. That is, the higher the value is, the more mafic in chemical compositions of the original tuffs. Authigenic montmorillonite and zeolite minerals were observed by SEM, which indicates diagenesis origin of bentonites. But the samples from the Chunbook Conglomerate showed only chaotically packed clay flakes in the matrix of sands or conglomerates, which implies detrital influence, not authigenic origin. The structural formulae of montmorillonite from these basins reflects their environment of formation. Fe (Ⅵ) can show the redox condition of its past environment and much lower
ratios in montmorillonite of the Chunbook Conglomerate imply the greater oxidizing influence. Calculated burial depths from oxygen stable isotope data of the samples from the Chunbook Conglomerate generally fall to the range of 929~963 m whereas the real burial depth of this area is only 530~580 m. This could be explained as the bentonites of the Chunbook conglomerate had not been formed in situ. Discriminant analyses with the data from chemical analyses and structural formulae of montmorillonites show that bentonites from three different basins could definitely be distinguished with each other. This result arises from the different chemical compositions of original volcanic ashes and the difference of sedimentary environments.
Mesozoic Granitoids and Associated Gold-Silver Mineralization in Korea
Economic and Environmental Geology, volume 34, issue 1, 2001, Pages 25~38
Contrasts in the style of the gold-silver mineralization in geologic and tectonic settings in Korea, together with radiometric age data, reflect the genetically different nature of hydrothermal activities, coinciding with the emplacement age and depth of Mesozoic magmatic activities. It represents a clear distinction between the plutonic settings of the Jurassic Daebo orogeny and the subvolcanic environments of the Cretaceous Bulgugsa igneous activities. During the Daebo igneous activities (about 200-130 Ma) coincident with orogenic time, gold mineralization took place between 197 and 127 Ma. The Jurassic deposits commonly show several characteristics: prominent association with pegmatites, low Ag/Au ratios in the ore-concentrating parts, massive vein morphology and a distinctively simple mineralogy including Fe-rich sphalerite, galena, chalcopyrite, Au-rich eIectrum. pyrrhotite and/or pyrite. During the Bulgugsa igneous activities (120-60 Ma), the precious-metal deposits are generally characterized by such features as complex vein morphology, medium to high AgiAu ratios in the ore concentrates, and abundance of ore minerals including base-metal sulfides, Ag sulfides, native silver, Ag sulfosalts and Ag tellurides. Vein morphology, mineralogical, fluid inclusion and stable isotope results indicate the diverse genetic natures of hydrothermal systems. The Jurassic Au-dominant deposits were formed at the relatively high temperature (about 300 to 450
C) and deep-crustal level (>3.0 kb) from the hydrothermal fluids containing more amounts of magmatic waters (3180; 5-10 %0). It can be explained by the dominant ore-depositing mechanisms as CO2 boiling and sulfidation, suggestive of hypo/mesothermal environments. In contrast, mineralization of the Cretaceous Au-Ag type (108-71 Ma) and Agdominant type (98-71 Ma) occurred at relatively low temperature (about 200 to 350
C) and shallow-crustal level «1.0 kb) from the ore-fonning fluids containing more amounts of less-evolved meteoric waters (15180; -10-5%0). These characteristics of the Cretaceous precious-metal deposits can be attributed to the complexities in the ore-precipitating mechanisms (mixing, boiling, cooling), suggestive of epilmesothermal environments. Therefore, the differences of the emplacement depth between the Daebo and the Bulgugsa igneous activities directly influence the unique temporal and spatial association of the deposit type.
Geochemistry, Secondary Contamination and Heavy Metal Behavior of Soils and Sediments in the Tohyun Mine Creek, Korea
Economic and Environmental Geology, volume 34, issue 1, 2001, Pages 39~53
Environmental pollution of the Tohyun mine creek area was investigated on the basis of geology, mineralogy and geochemistry. In soils and sediments of the mine area,
ratios are partly negative correlation against
, respectively. Geochemical characteristics of some trace and rare earth elements such as V/Ni, Ni/Co, La/Ce, Th/Yb, Th/U, La/Th,
, La/Sc and Sc/Th are revealed a narrow range and homogeneous compositions may be explained by simple source lithology. These results suggest that sediments source of the host shale around the mine area could be originated by basic to intermediate igneous rocks. Mineral compositions of soil and sediment near the mine area were partly variable mineralogy, which are composed of quartz, mica, feldspar, chlorite, clay minerals and some pyrite. Soils and sediments with highly concentrated heavy minerals, gravity separated mineralogy, are composed of some pyrite, arsenopyrite, chalcopyrite, sphalerite, galena, goethite and various kinds of hydroxide minerals on the polished sections. As normalized by bed rock composition, average enrichment indices of major elements in sediments, precipitates, farmland soils and paddy soils are 1.0, 1.7, 0.9 and 0.8, respectively. Maximum concentration of environmental toxic elements in the mine creek are detected with Ag = 186 ppm, As = 17,100 ppm, Bi = ]27 ppm, Cd = 77 ppm, Cu = 12,299 ppm, Pb = 8,897 ppm, Sb = 1,350 ppm, W = 599 ppm and Zn = 12,250 ppm, which are increasing with total FeO increasing, and extremely high concentrations of surface sediments and precipitates near the waste rock dump. These toxic elements (As, Bi, Cd, Cu, Pb, Sb, W and Zn) of the samples, normalizing by host rock concentration, revealed that average enrichment index is 106.0 for sediments, 279.6 for precipitates, 3.5 for farmland soils and 1.6 for paddy soils. However, on the basis of EPA values, enrichment indices of all the samples are 40.7, 121.4, 1.3 and 0.6, respectively.
Petrochemistry of Granitoids in the Younggwang-Kimje area, Korea
Economic and Environmental Geology, volume 34, issue 1, 2001, Pages 55~70
Granitoids in the Younggwang-Kimje area can be divided into two types of granite. One is foliated granite (Cheongup and Kochang foliated granites) developed along the NE-SW direction kwangju fault system and the other is undeformed granite (Kimje and Younggwang granites) developed in the western part of the area.
content of study area, Younggwang granite is 62.8-74.0%, Kochang foliated granite is 64.5-74.4%, Cheongup foliated granite is 64.5-70.2%, Kimje granite is 63.4-72.0%. The result indicated that these granitoids belong to the intermediate and acidic rock. In Harker's diagram, as
, MgO, CaO,
s and MnO decrease, but
increases. In AFM diagram, Younggwang granite, Kochang foliated granite, Cheongup foliated granite and Kimje granite belong to calk-alkaline rock series. And in triangular diagrams of normative Qz-Or-Pl and An-Ab-Or, they are located in granodiorite and granite region. On the co-variation diagrams of trace elements with silica, Ba, Co, Li, Nb, An, Rb elements show increasing patterns. The diagrams of ACF and
ratios indicate that granitoids of the study area belong to I-type.
Geochemistry and Isotope Studies of the Shinchon
-rich Waters in the Gyeongsang Province
Economic and Environmental Geology, volume 34, issue 1, 2001, Pages 71~88
The Geochemica] and isotope studies on the
-rich water from the Shinchon area were carried out. The Shinchon
-rich water belongs to Ca(Na)-
type showing very high
atm) and TDS (835-3,144 mg/L). The results of geochemical and isotope analysis indicate that
gas is originated from the deep seated source such as mantle or magmatic gases. The
-rich water was evolved by interaction with deep-seated granite and major water-rock interaction was dissolution of p]agioclase resulting high Na content of
-rich water. Precipitation and dissolution of secondary calcite might be accompanied with the dissolution of plagioclase maintaining Na/Ca ratio. High contents of K and
indicate that the geochemical characteristics of
-rich water were partially affected by interaction with upper sedimentary rock during uprising to surface. N03 and tritium contents suggest that the
-rich water was mixed with low
groundwater at some locations. The oxygen-hydrogen isotopes show that all water samples were derived from meteoric waters and the
-rich water was isotopically re-equilibrated with lighter
gas. Although some carbon isotope data show isotopically heavy values, carbon isotope data indicate that the
gas was possib]y derived by deep source.
The State and Sources of Contamination with Heavy Metals and Anion in Stream Within Chonju City
Economic and Environmental Geology, volume 34, issue 1, 2001, Pages 89~104
The Chonju and Samchun streams are passing though Chonju city and several contamination sources are located along these streams. The Samchun stream joins the Chonju stream in the Gosapyeong waste disposal site and the Chonju stream finally joins to the Mankyeong River. The objectives of this study are to determine the state and sources of contamination for heavy metals and anions in the Chonju and Samchun streams and to evaluate the effect of these streams on the contamination of the Mankyeong River. In order to select sampling locations, a stratified random sampling method was used. These streams was divided into several parts according to the expected contamination state, and samples were selected randomly from these parts. Generally, the water qualities of these streams were generally below the Drinking Water Level at the time of sampling in various heavy metals and anions. However, the levels of AI, Fe,
, Cl- in these streams could be higher during dry season due to continuous inputs from various contamination sources. This study identified several contamination sources for these streams; two waste disposal sites along these streams for Fe, Mn, AI, Zn and
, the Chonju Waste Water Treatment Plant for Zn, Mn,
and the untreated sewages for AI, Zn, Mn,
. This study also revealed that the Chonju stream itself is an important contamination source for Fe, Mn,
in the Mankyung River.
Fluorine Distribution and Attenuation of Groundwater within Limestone and Granite from Keumsan-Wanju Fluorite Mineralized Zone
Economic and Environmental Geology, volume 34, issue 1, 2001, Pages 105~117
The characteristics of hydrogeochemistry and fluorine distribution in drinking groundwater from limestone and granite were studied in the Keumsan-Wanju area, where major important fluorite-deposits are distributed. The hydrochemical properties of groundwater from studied area arc commonly characterized as
water type. However, some of the groundwater samples collected from Jurassic and Cretaceuus granites belong to
type, respectively. The contamination of drinking groundwater by minewater from the nearby fluorite deposits is not found yet. However, groundwater having high F contents up to 1].4 mgll, which is higher than the drinking water limit, is found from the wells located in Cretaceous granite. The tluorine contents in groundwater generally increase with increasing well depth. The concentrations of F in the groundwater show a positive relationship with the values of Na,
, pH, whereas a negative relationship with Ca. The positive correlation of F-concentrations to major elements (
, Na, CI) and trace elements (Li, B, Rb) may suggest that the groundwater come from the decomposition of tluoride-bearing silicate minerals within highly differentiated granitic rocks, Therefore, wells for drinking water should not be developed or should be drilled within shallow level in the Cretaceous granite region to reduce the F contents in the groundwater.
Paleomagnetic Study on Cretaceous Rocks in Haenam Area
Economic and Environmental Geology, volume 34, issue 1, 2001, Pages 119~131
A mean characteristic remanent magnetization was obtained for the first time in Korea from volcanic and pyroclastic sedimentary rocks distributed in Haenam Area, located in southwestern part of the Korean Peninsula. The age of the prevailing rocks in this area belongs mostly to Late Cretaceous, with a few exceptions of Early Cretaceous, mainly based on K/Ar whole rock age dating. Characteristic remanent magnetizations of these have both normal and reverse polarities with antipodal direction, which were interpreted to be the primary remanent magnetizations obtained by the ambient Earth's magnetic field at the time of formation of the concerned rocks. The source magnetic minerals of the remanent magnetization has been identified as magnetite. The mean direction of characteristic remanent magnetization obtained from the Late Cretaceous rocks in this study is Dm/Im=21.4 supper(o)/57.1 supper(o) (
, k=350.0). The paleomagnetic pole position calculated from this result for the Late Cretaceous, is
), which matches well with those of 80 Ma (
) and 90 Ma (
) of the Eurasian Continent's APWP (Apparent Polar Wander Path). This result strongly indicates that the studied area, belonging to the Eurasian Continent, have suffered very little geotectonic movement after the Late Cretaceous. The deflection of declination of remanence from Early Cretaceous rocks in the study area may indicate that the micro-block was counterclockwisely rotated with vertical axis between the late of Early Cretaceous and the early of Late Cretaceous.
Palaeomagnetism of the Okchon Belt, Korea : Anisotropy of Magnetic Susceptibility (AMS) and Deformation of the Hwanggangri Formation in Chumgju-Suanbo Area
Economic and Environmental Geology, volume 34, issue 1, 2001, Pages 133~146
We report the results of structural field observation and measurement of anisotropy of magnetic susceptibility (AMS) of the diamictitic Hwanggangri Formation distributed in Chungju-Suanbo area of the Okchon Belt, Korea. The outcrops of the Hwanggangri Formation show two types of cleavage in general: slaty cleavage (SI) and crenulation cleavage (5z). 5] cleavage is, however, well observable only in the notheastem (NE) part of study area, while overwhelmed by 52 cleavage in the southwestern (5W) part, indicating stronger later deformation in 5W part of the study area. This partitioning of the study area is corroborated by both IRM and AMS parameters: NE part of the study area is characterized by higher IRM intensity, higher bulk magnetic susceptibility, higher AM5 degree, and by oblate shape of magnetic susceptibility ellipsoid. Their values become drastically lowered toward southwest, and reach to a stable minimum in the whole 5W part of the study area. In addition, degree of both metamorphism and deformation tends to increase gradually from northeast toward southwest and also from northwest toward southeast in the study area. Based on the distribution pattern of the principal axes (
axes) of magnetic anisotropy ellipsoids revealed in the NE part of the study area, three episodes of deformation (
) are recognized: D_1$ deformation produced
cleavage with NE-5W trend, which is caused by a strong NW-SE tlattening of a coaxial pure shear.
deformation produced 5z cleavage characterized by a non-coaxial deformation. It was caused by a ductile or semi-ductile thrusting toward NW and concurrent sinistral shearing along
cleavage plane. Lastly,
deformation produced tlexural folding of all previous structures with a nearly horizontal NE fold axis. Distribution pattern of the principal axes of magnetic anisotropy ellipsoid from the SW part of the study area, on the other hand, does not show any coherency among sites or samples. We interpret that this dispersed pattern of
axes together with lower anisotropy strength indicates that magnetic fabrics in the SW part have been disturbed either by a superposition of strong deformation/metamorphism or by a kind of reciprocal strain due to an overlapping of
or by both processes.
Low-temperature Aqueous Oxidation of Titanomagnetites: Changes in Magnetic Properties of Pseudo-single Domain Particles
Economic and Environmental Geology, volume 34, issue 1, 2001, Pages 147~156
Titanomagnetites, the primary magnetic mineral in submarine basalts, generally has undergone some degree of low temperature oxidation to cation-deficient titanomaghemites. Synthetic analogues of natural titanomaghemite have been prepared by the removal of iron mechanism employing a low-temperature aqueous oxidation method. Along with the low-temperature oxidation of titanomagnetite, magnetic properties of titanomagnetite change sensitively. The results show that as the degree of oxidation increases, the Curie temperature (Tc) increases from
, saturation magnetization (Ms) at room temperature decreases from 126.30 kAlm (25.26 emu/g) to 16.55 kAlrn (3.31 emu/g) monotonously, and coercive force (Hc) and coercivity of remanence (Hcr) increase from 6.13 kAlm (77 Oe) and 23.24 kAlm (292 Oe) to 38.83 kNm (488 Oe) and 47.03 kAlm (591 Oe), respectively. Low field susceptibility (X) decreases from
. Based on the results of this study, it is interpreted that the NRM intensity variations of the oceanic crust of presetnt day to 30 Ma is due to the formation of titanomahemites of various degree of oxidation by the low-temperature aqueous oxidation of titanomagnetite, while the magnetic intensity changes of the oceanic crust older than 30 Ma is presumably caused by the combined effect of the formation of titanomaghemites and subsequent inversion of titanomagnemites. DetaileJ causes of the variations of NRM intensity of the oceanic crust may be revealed by systematic studies of the oceanic-floor basalts in the future.