• Proceedings of the Korean Vacuum Society Conference
• /
• 2012.02a
• /
• pp.420-420
• /
• 2012

ZnO seed layer were deposited on quartz substrate by sol-gel method and prism-like Al-doped ZnO nanorods (AZO nanorods) were grown on ZnO seed layer by hydrothermal method with various Al concentration ranging from 0 to 2.0 at.%. Structural and optical properties of the AZO nanorods were investigated by field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), photoluminescence (PL). The diameter of the AZO nanorods was smaller than undoped ZnO nanorods and its diameter of the AZO nanorods decreased with increasing Al concentration. In XRD spectrum, it was observed that stress and full width at half maximum (FWHM) of the AZO nanorods decreased and the 'c' lattice constant increased as the Al concentration increased. From undoped ZnO nanorods, it was observed that the green-red emission peak of deep-level emission (DLE) in PL spectra. However, after Al doping, not only a broad green emission peak but also a blue emission peak of DLE were observed.

• Economic and Environmental Geology
• /
• v.24 no.2
• /
• pp.83-96
• /
• 1991

Haenam pyrophyllite deposit occurred in the rhyolitic tuff of late Cretaceous age is located in the northern part of Haenam-gun, Jeonranam-do. The ore of the Haenam deposit is predominantly composed of pyrophyllite and illite accompanying such clay minerals as kaolinite, chlorite, and smectite. Pyrophyllite ore at the center of altered mass is often associated with kaolin minerals and high temperature minerals such as corundum, andalusite, and diaspore. On the basis of mineral assemblage the Haenam deposit can be devided into three alteration zones from the center to the margin of the deposit; the pyrophyllite zone, kaolinite zone, and illite zone. All alteration zones are associated with appreciable amounts of chalcedonic quartz. Those mineral assemblages indicate that hydrothermal solution which produced the Haenam deposit is strongly acidic solution with high silica and hydrogen activity and low $SO_4{^{2-}}$ activity. Discriminant analysis shows that $Na_2O$, $K_2O$, and $Al_2O$, of major elements are discriminant elements which classify alteration zones, while in case of trace elements Cr, Ni, and Sr turned out to be discriminant elements in this deposit. According to the mineral assemblage and illite geothermometry, pyrophyllite ore is considered to have been formed at about $240-290^{\circ}C$. K-Ar isotopic age for illite from this deposit indicates that it was formed at much the same age of later stage volcanics in the area, suggesting that the hydrothermal alteration of these deposits is associated with later volcanism of the area.

• Bulletin of the Korean Chemical Society
• /
• v.34 no.11
• /
• pp.3335-3339
• /
• 2013

Boron-doped ZnO (BZO) nanorods were grown on quartz substrates using hydrothermal synthesis, and the temperature-dependence of their photoluminescence (PL) was measured in order to investigate the origins of their PL properties. In the UV range, near-band-edge emission (NBE) was observed from 3.1 to 3.4 eV; this was attributed to various transitions including recombination of free excitons and their longitudinal optical (LO) phonon replicas, and donor-acceptor pair (DAP) recombination, depending on the local lattice configuration and the presence of defects. At a temperature of 12 K, the NBE produces seven peaks at 3.386, 3.368, 3.337, 3.296, 3.258, 3.184, and 3.106 eV. These peaks are, respectively, assigned to free excitons (FX), neutral-donor bound excitons ($D^{\circ}X$), and the first LO phonon replicas of $D^{\circ}X$, DAP, DAP-1LO, DAP-2LO, and DAP-3LO. The peak position of the FX and DAP were also fitted to Varshni's empirical formula for the variation in the band gap energy with temperature. The activation energy of FX was about ~70 meV, while that of DAP was about ~38 meV. We also discuss the low temperature PL near 2.251 eV, related to structural defects.

• Journal of the Mineralogical Society of Korea
• /
• v.13 no.4
• /
• pp.171-185
• /
• 2000

Siliceous mudstones are embedded on a large scale in the Tertiary formations of Pohang area. Some useful zeolites such as NsP, (Na, TMA)P, analcime and hydroxysodalite were synthesized from the siliceous mudstones by treating with the variety of solution, i.e ., NaOH, NaOH+NaCl, NaOH, NaOH+$NaAlO_2$and NaOH+TMAOH at the low-temperature hydrothermal system ranging 60~12$0^{\circ}C$. Major precursor of zeolites is found as opal-CT in the zeolite-forming reaction. Smectite, which is included in considerable amounts in the mudstone, appears to play a major role of Al-source in the zeolite synthesis. In comparison, chalcedonic quartz and mica are rather insoluble in alkaline solution, and thus, these are observed as major impurities in the reaction products. An addition of $NaAlO_2$to NaOH solution is effective for eliminating these impurities in the reaction procedure, through these are partly dissolved when elevating the reaction temperature, concentration, and time. Phase change from NaP to hydroxysodalite takes place at the NaOH concentrations of 3.0~4.0 M, and the reaction is not sensitive to the temperature shift. NaP is more stable at lower NaOH concentration and higher activity of $Na_{+}$ whereas analcime is sensitive to the temperature change and stable at higher than $100^{\circ}C$ and 2.0~4.0 M in NaOH concentration. For the pure NaP synthesis without any other products, the treatment of mudstones with 1:1 solution of NaOH and $NaAlO _2$ turns out to be quite effective. NaP was successfully synthesized together with analcime at $100^{\circ}C$ as well as lower concentrations of NaOH+NaCl solution. In addition, the organic type, (Na, TMA)P was formed together with smectite in the 1:1 solution of NaOH and TMAOH.

• Journal of the Korean earth science society
• /
• v.29 no.7
• /
• pp.551-558
• /
• 2008

The Soowang deposits occur in the quartz veins that were filled fissures in the middle Cretaceous porphyritic granite and/or the Precambrian Sobaegsan gneiss complex. Paragenetic studies suggest that the vein filling can be divided into four identifiable stages. Sphalerites were deposited by the cooling fluids at stages I, II, and III. The results of microscopic observation and EPMA analysis suggest that the chalcopyrite dots and disease in sphalerite are replacement products by later hydrothermal solution at the early stage III. The inferred processes of chalcopyrite disease are as follows: (1) Fe enrichment to the margins and along the cracks of the Fe-poor sphalerite by Fe-rich solution, (2) Formation of chalcopyrite dots in the Fe-enriched sphalerite formed at the stage II, and Fe reduction of sphalerite near the chalcopyrite dots by Cu-bearing solution, (3) Formation of "chalcopyrite disease" penetrating the compositional zoning of sphalerite at the early stage III.

• Economic and Environmental Geology
• /
• v.35 no.4
• /
• pp.299-316
• /
• 2002

The Samkwang gold-silver deposits consist of gold-silver-bearing hydrothermal massive quartz veins which filled the fractures along fault shear (NE, NW) zones within Precambrian banded or granitic gneiss of Gyeonggi massif. Ore mineralization of this deposits occurred within a single stage of quartz vein which was formed by multiple episodes of fracturing and healing. Based on vein mineralogy and paragenesis, massive quartz veins are divided into two main paragenetic stages which are separated by a major faulting event. Main ore mineralization occurred at stage I. Wall-rock alteration from this deposits occur as mainly sericitization, chloritization, silicification and minor amounts of pyritization, carbonitization, propylitization and argillitization. Ore minerals are composed mainly of arsenopyrite (29.21-32.24 As atomic %), pyrite, sphalerite (6.45-13.82 FeS mole %), chalcopyrite, galena with minor amounts of pyrrhotite, marcasite, electmm (39.98-66.82 Au atomic %) and argentite. Systematic studies of fluid inclusions in early quartz veins and microcracks indicate two contrasting physical-chemical conditions: 1). temperature (215-345$^{\circ}$C) and pressure (1296-2022 bar) event with $H_{2}O-CO_{2}-CH_{4}-NaCl$fluids (0.8-6.3 wt. %) related to the early sulfide deposition, 2). temperature (203-441$^{\circ}$C) and pressure (320 bar) event with $H2_{O}$-NaCI $\pm$ $CO_{2}$ fluids (5.7-8.8 wt. %) related to the late sulfide and electrum assemblage. The H20-NaCI $\pm$ $CO_{2}$ fluids represent fluids evolved through fluid unmixing of an $H_{2}O-CO_{2}-CH_{4}-NaCl$fluids due to decreases in fluid pressure and influenced of deepcirculated meteoric waters possibly related to uplift and unloading of the mineralizing suites. Calculated sulfur isotope compositions (${\delta}^{34}S_{fluid}$) of hydrothermal fluids (1.8-4.9$\textperthousand$) indicate that ore sulfur was derived from an igneous source. Measured and calculated oxygen and hydrogen isotope compositions (${\delta}^{18}O_{I120}$, ${\delta}D$) of ore fluids (-5.9~10.9$\textperthousand$, -102~-87$\textperthousand$) indicate that mesothermal auriferous fluids at Samkwang gold-silver deposits were likely mixtures of $H_{2}O$-rich, isotopically less evolved meteoric water and magmatic fluids.

• Economic and Environmental Geology
• /
• v.27 no.2
• /
• pp.147-160
• /
• 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
• /
• v.28 no.4
• /
• pp.337-350
• /
• 1995

The Hwacheon-ri mineralized area is located within the Cretaceous Gyeongsang Basin of the Korean peninsula. The mineralized area includes the Hwacheon, Daeweon, Kuryong and Cheongryong mines. Each of these mines occurs along copper-bearing hydrothermal quartz veins that crosscut late Cretaceous volcanic rocks, although some disseminated ores in host rocks also exist locally. Mineralization can be separated into three distinct stages (I, II, and III) which developed along preexisting fracture zones. Stage I is ore-bearing, whereas stages II and III are barren. The main phase of ore mineralization, stage I, can be classified into three substages (Ia, Ib and Ic) based on ore mineral assemblages and textures. Substage Ia is characterized by pyrite-arsenopyrite-molybdenite-pyrrhotite assemblage and is most common at the Hwacheon deposit. Substage Ib is represented by main precipitation of Cu, Zn, and Pb minerals. Substage Ic is characteristic of hematite occurrence and is shown only at the Kuryong and Cheongryong deposits. Some differences in the ore mineralization at each mine in the area suggest that the evolution of hydrothermal fluids in the area varied in space (both vertically and horizontally) with respect to igneous rocks relating the ore mineralization. Fluid inclusion data show that stage I ore mineralization mainly occurred at temperatures between ${\approx}350^{\circ}$ and ${\approx}200^{\circ}C$ from fluids with salinities between 9.2 and 0.5 wt.% eq. NaCl. In the waning period of substage Ia, the high temperature and salinity fluid gave way to progressively cooler, more dilute fluids of later substage Ib and Ic (down to $200^{\circ}C$, 0 wt.% NaCl). There is a systematic decrease in the calculated ${\delta}^{18}O_{H2O}$ values with paragenetic time in the Hwacheon-ri hydrothermal system from values of ${\approx}2.7$‰ for substage Ia, through ${\approx}-2.8$‰ for substage Ib, to ${\approx}-9.9$‰ for substage Ic. The ${\delta}D$ values of fluid inclusion water also decrease with decreasing temperature (except for the Daeweon deposit) from -62‰ (substage Ia) to -80‰ (substage Ic and stage III). These trends are interpreted to indicate the progressive cooler, more oxidizing unexchanged meteoric water inundation of an initial hydrothermal system which is composed of highly exchanged meteoric water. Equilibrium thermodynamic interpretation of the mineral assemblages with the variation in amounts of chalcopyrite through the paragenetic time, and the evolution of the Hwacheon-ri hydrothermal fluids indicate that the solubility of copper chloride complexes in the hydrothermal system was mainly controlled by the variation of temperature and $fo_2$ conditions.

• Economic and Environmental Geology
• /
• v.51 no.3
• /
• pp.213-222
• /
• 2018

Metasediment-hosted Pb-Zn mineralized zone has been found in Dyusembay of Kazakhstan. Its petrological properties, metal index, alteration index and redox-sensitivity are compared with those of SEDEX type deposit. Mineralization is developed along foliation of host rock (graphitic phyllite) and controlled by folds and faults; major ore minerals including pyrite, pyrrhotite, sphalerite, and galena are disseminated or interlayered with fine-grained quartz. The margin of the mineralized zone is metamorphosed accompanying sericite and chlorite. Hydrothermal brecciation and Pb-Zn mineralization formed in quartz-calcite stockworks are confirmed at the around of Maytyubin granitoid intrusions. The mineralization is classified into three types according to those of occurrence, paragenesis, chemical composition and isotopic characteristics. Type 1 whose fine-grained pyrite, pyrrhotite and sphalerite are formed in parallel yet discontinuous to well-developed foliations of the host rock; its geochemistry is similar to those of the earlier stage in SEDEX-type mineralization. In case of type 2, the ore minerals of which are concentrated being parallel to a foliation by regional metamorphism, and most of them associated with quartz and muscovite (${\pm}$ biotite) paragenetically. Type 3 is formed in the hydrothermal breccia zone whose ore minerals are controlled by foliation and breccia and developed in quartz ${\pm}$ calcite veins having a form such as stratification, stockwork or veinlets. Host rocks in the mineralized zone indicate homogeneous metamorphic grade and there is no specific alteration zonation. Also, all types (type 1, type 2, and type 3) represent similar REEs patterns, it can be interpreted that these are originated from a same source. Sulphides occurred in mineralized zone indicate a limited range of sulphur isotope values (type 2, ${\delta}^{34}S=-13.3{\sim}-11.7$‰; type 3, ${\delta}^{34}S=-13.9{\sim}-8.2$‰), and a result of geothermometry presents different temperature ranges: type 2($251{\pm}38^{\circ}C{\sim}277{\pm}40^{\circ}C$); type 3($360{\pm}2^{\circ}C$ to $537{\pm}29^{\circ}C$). It is estimated to be due to the effect of metamorphism and Maytyubin granitoid intrusions, respectively. In addition, ternary chart of thorium, scandium, and zircon for discrimination of tectonic setting and redox sensitivity using V/Mo values indicate that hydrothermal sediments put on reduction environment after precipitation, before being affected by metamorphism and intrusion activity. Geochemical data are plotted on a distal trend of SEDEX-type with discrimination plot using SEDEX index. As a result, petrological-geochemical properties demonstrate that Dyusembay Pb-Zn mineralized zone is comparable to distal-type of SEDEX deposit.

• Economic and Environmental Geology
• /
• v.35 no.5
• /
• pp.379-393
• /
• 2002

Within the Boseong-Jangheung area of Korea, five hydrothermal gold (-silver) quartz vein deposits occur. They have the characteristic features as follows: the relatively gold-rich nature of e1ectrurns; the absence of Ag-Sb( -As) sulfosalt mineral; the massive and simple mineralogy of veins. They suggest that gold mineralization in this area is correlated with late Jurassic to Early Cretaceous, mesothermal-type gold deposits in Korea. Fluid inclusion data show that fluid inclusions in stage I quartz of the mine area homogenize over a wide temperature range of 200$^{\circ}$ to 460$^{\circ}$C with salinities of 0.0 to 13.8 equiv. wt. % NaCI. The homogenization temperature of fluid inclusions in stage II calcite of the mine area ranges from 150$^{\circ}$ to 254$^{\circ}$C with salinities of 1.2 to 7.9 equiv. wt. % NaCI. This indicates a cooling of the hydrothermal fluid with time towards the waning of hydrothermal activity. Evidence of fluid boiling including CO2 effervescence indicates that pressures during entrapment of auriferous fluids in this area range up to 770 bars. Calculated sulfur isotope composition of auriferous fluids in this mine area (${\delta}^34S$_{{\Sigma}S}$$\textperthousand$) indicates an igneous source of sulfur in auriferous hydrothermal fluids. Within the Sobaegsan Massif, two representative mesothermal-type gold mine areas (Youngdong and Boseong-Jangheung areas) occur. The ${\delta}^34S values of sulfide minerals from Youngdong area range from -6.6 to 2.3$\textperthousand$ (average=-1.4$\textperthousand$, N=66), and those from BoseongJangheung area range from -0.7 to 3.6$\textperthousand$ (average=1.6$\textperthousand$, N=39). These i)34S values of both areas are comparatively lower than those of most Korean metallic ore deposits (3 to 7TEX>$\textperthousand$). And, within the Sobaegsan Massif, the ${\delta}^34S values of Youngdong area are lower than those of Boseong-Jangheung area. It is inferred that the difference of ${\delta}^34S values within the Sobaegsan Massif can be caused by either of the following mechanisms: (1) the presence of at least two distinct reservoirs (both igneous, with ${\delta}^34S values of < -6 $\textperthousand$ and 2$\pm$2 %0) for Jurassic mesothermal-type gold deposits in both areas; (2) different degrees of the mixing (assimilation) of 32S-enriched sulfur (possibly sulfur in Precambrian pelitic basement rocks) during the generation and/or subsequent ascent of magma; and/or (3) different degrees of the oxidation of an H2S-rich, magmatically derived sulfur source ${\delta}^34S = 2$\pm$2$\textperthousand$) during the ascent to mineralization sites. According to the observed differences in ore mineralogy (especially, iron-bearing ore minerals) and fluid inclusions of quartz from the mesothermal-type deposits in both areas, we conclude that pyrrhotite-rich, mesothermal-type deposits in the Youngdong area formed from higher temperatures and more reducing fluids than did pyrite(-arsenopyrite)-rich mesothermal-type deposits in the Boseong-Jangheung area. Therefore, we prefer the third mechanism than others because the ${\delta}^34S values of the Precambrian gneisses and Paleozoic sedimentary rocks occurring in both areas were not known to the present. In future, in order to elucidate the provenance of ore sulfur more systematically, we need to determine ${\delta}^34S values of the Precambrian metamorphic rocks and Paleozoic sedimentary rocks consisting the basement of the Korean Peninsula including the Sobaegsan Massif.