• Economic and Environmental Geology
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• v.27 no.2
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• pp.147-160
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• 1994

Copper-bearing hydrothermal vein mineralization of the Samsan area was deposited in two stages (I and II) of quartz-calcite-sulfide veins which fill fissures in Cretaceous volcanic and sedimentary rocks of the Gyeongsang basin. The major ore minerals, chalcopyrite and sphalerite, together with pyrite, galena, hematite, and minor sulfosalts, occur with epidote and chlorite as gangue minerals in stage I quartz veins. Chlorite geothermometry, fluid inclusion and stable isotope data indicate that copper ore was deposited mainly at temperatures between $330^{\circ}C$ and $280^{\circ}C$ from fluids with salinities between 12 and 3 equiv. wt % NaCl. Evidence of fluid boiling indicates a range of pressures from ${\leq}100$ to 200 bars bars. Within ore stage I there was an apparent decrease in ${\delta}^{34}S$ values of $H_{2}S$ with paragenetic time, from 8.0 to 2.3 per mil. This pattern was likely achieved through progressive increases in activity of oxygen accompanying boiling and mixing. In the early part of the first stage, the high temperature, high salinity fluids gave way to progressively cooler and more dilute fluids of the late parts in the first stage and of the second stage. There is a systematic decrease in calculated ${\delta}^{18}O_{water}$ values with decreasing temperature in the Samsan hydrothermal system, from values of -86 per mil for early portion of stage I through -5.9 per mil for late portion of stage I to -6.3 per mil for stage II. The ${\delta}D$ values of fluid inclusion waters also decrease with paragenetic time from -76 per mil to -86 per mil. These trends combined with mineral paragenesis and fluid inclusion data are interpreted to indicate progressive cooler, more oxidizing meteoric water inundation of an early exchanged meteoric hydrothermal system.

• Economic and Environmental Geology
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• v.22 no.4
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• pp.303-314
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• 1989

The electrum-silver-sulfide mineralization of the Geojae island area was deposited in three stages (I, II, and carbonate) of quartz and calcite veins that crosscut Late Cretaceous volcanic rocks and granodiorite(83 m.y.). Stages I and II were terminated by the onset of fractunng and breCCIation events. Fluid inclusion data suggest that the gold-sulfide-bearing stages I and II each evolved from an initial high temperature( near $370^{\circ}C$) to a later low temperature(near $200^{\circ}C$). Each of those stages represented a separate mineralizing system which cooled prior to the onset of the next stage. The relationship between homogenization temperature and salinity in stages I and II suggests a complex history of boiling, cooling and dilution. Evidence of boiling indicates a pressure of < 100 bars, corresponding to a depth of 500 to 1,250m assummg hthostatlc and hydrostatic pressure regimes, respectively. Fluid inclusion and mineralogical evidence suggest that the electrum-silver mineralization was deposited at a temperature of $220-260^{\circ}C$ from ore fluids with salinities between 1.9 and 8.1 equivalent wt.% NaCl. Total sulfur concentration is estimated to be $10^{-3}$ to $10^{-4}$ molal. The estimated $fs_2$ and $fo_2$ range from $10^{-11.8}$ to $10^{-14}$ atm and $10^{-35}$ to $10^{-36}$ atm, respectively. The chemical conditions indicate that the dominant sulfur species in the ore forming fluids was a reduced form($H_2S$). Rapid cooling and dilution of ore-forming fluids by mixing with less-evolved meteoric waters led to gold-silver deposition through the breakdown of the bisulfide complex($Au(HS)_2$) as the activity of $H_2S$ decreased.

• Reproductive and Developmental Biology
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• v.30 no.1
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• pp.65-70
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• 2006

This study investigated apoptosis and in vitro development of parthenogenetic preimplantation porcine embryos. In vitro matured oocytes for $42{\sim}44h$ were used. Apoptotic cell death was analyzed by using a terminal deoxynucleatidyl transferase mediated deoxyuridine 5-triphosphate nick-end tabling (TUNEL) assay. In experiment 1, oocytes were activated with two electric pulses (CH) of 1.2 kV/cm for $30{\mu}sec$ (E), E + 6-dimethylaminopurine (6-DMAP) or E + cycloheximide (CH) and cultured in PZM-3 under 5% $CO_2$ in air at $38.5^{\circ}C$. In experiment 2, oocytes were activated by E and cultured in PZM-3 or NCSU-23 under a gas atmosphere of 20% $O_2$ ($5%\;CO_2$, in air) or 5% $O_2$ $(5%\;CO_2,\;5%\;O_2\;90%\;N_2)\;at\;38.5^{\circ}C$. Oocytes activated with E+6-DMAP or E+CH showed higher blastocyst rates (36.3% and 32.5%) compared to E alone (27.7%). The frequency of apoptosis according to treatments were 5.3%, 7.7% and 7.1% respectively. Oocytes activated with E alone showed lower (P<0.05) frequency of apoptosis compared to other groups. In experiment 2, parthenotes cultured in PZM-3 showed slightly higher blastocyte rates (28.2% and 29.7%) compared to NCSU-23 (22.6% and 24.4%) regardless of atmosphere. Blastocysts generated in PZM-3 showed lower (P<0.05) apoptosis rate under 20% $O_2$ (9.2% vs 16.9%), whereas those in NCSU-23 had slightly lower apoptosis rate under 5% $O_2$ (14.0% vs 18.4%). This result represents that activation method and culture condition could affect the frequency of apoptosis as well as in vitro developmental rate.

• Economic and Environmental Geology
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• v.30 no.4
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• pp.289-301
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• 1997

The Boguk cobalt mine is located within the Cretaceous Gyeongsang Sedimentary Basin. Major ore minerals including cobalt-bearing minerals (loellingite, cobaltite, and glaucodot) and Co-bearing arsenopyrite occur together with base-metal sulfides (pyrrhotite, chalcopyrite, pyrite, sphalerite, etc.) and minor amounts of oxides (magnetite and hematite) within fracture-filling $quartz{\pm}actinolite{\pm}carbonate$ veins. These veins are developed within an epicrustal micrographic granite stock which intrudes the Konchonri Formation (mainly of shale). Radiometric date of the granite (85.98 Ma) indicates a Late Cretaceous age for granite emplacement and associated cobalt mineralization. The vein mineralogy is relatively complex and changes with time: cobalt-bearing minerals with actinolite, carbonates, and quartz gangues (stages I and II) ${\rightarrow}$ base-metal sulfides, gold, and Fe oxides with quartz gangues (stage III) ${\rightarrow}$ barren carbonates (stages IV and V). The common occurrence of high-temperature minerals (cobalt-bearing minerals, molybdenite and actinolite) with low-temperature minerals (base-metal sulfides, gold and carbonates) in veins indicates a xenothermal condition of the hydrothermal mineralization. High enrichment of Co in the granite (avg. 50.90 ppm) indicates the magmatic hydrothermal derivation of cobalt from this cooling granite stock, whereas higher amounts of Cu and Zn in the Konchonri Formation shale suggest their derivations largely from shale. The decrease in temperature of hydrothermal fluids with a concomitant increase in fugacity of oxygen with time (for cobalt deposition in stages I and II, $T=560^{\circ}C-390^{\circ}C$ and log $fO_2=$ >-32.7 to -30.7 atm at $350^{\circ}C$; for base-metal sulfide deposition in stage III, $T=380^{\circ}-345^{\circ}C$ and log $fO_2={\geq}-30.7$ atm at $350^{\circ}C$) indicates a transition of the hydrothermal system from a magmatic-water domination toward a less-evolved meteoric-water domination. Sulfur isotope data of stage II sulfide minerals evidence that early, Co-bearing hydrothermal fluids derived originally from an igneous source with a ${\delta}^{34}S_{{\Sigma}S}$ value near 3 to 5‰. The remarkable increase in ${\delta}^{34}S_{H2S}$ values of hydrothermal fluids with time from cobalt deposition in stage II (3-5‰) to base-metal sulfide deposition in stage III (up to about 20‰) also indicates the change of the hydrothermal system toward the meteoric water domination, which resulted in the leaching-out and concentration of isotopically heavier sulfur (sedimentary sulfates), base metals (Cu, Zn, etc.) and gold from surrounding sedimentary rocks during the huge, meteoric water circulation. We suggest that without the formation of the later, meteoric water circulation extensively through surrounding sedimentary rocks the Boguk cobalt deposits would be simple veins only with actinolite + quartz + cobalt-bearing minerals. Furthermore, the formation of the meteoric water circulation after the culmination of a magmatic hydrothermal system resulted in the common occurrence of high-temperature minerals with later, lower-temperature minerals, resulting in a xenothermal feature of the mineralization.