• Title/Summary/Keyword: Low sulfidation

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SUBMILLIMETER SCALE VARIATION OF THE OXYGEN ISOTOPE COMPOSITION OF GOLD-BEARING QUARTZ VEIN AT THE HISHIKARI DEPOSIT, JAPAN

  • Hayashi, Ken-ichiro
    • Proceedings of the KSEEG Conference
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    • 2003.04a
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    • pp.20-23
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    • 2003
  • Low-sulfidation style ore deposits, the major source of Au, Ag, and Hg, are formed from neutral-pH, reduced hydrothermal solutions close to equilibrium with their host rocks. The waters are low-salinity (〈1 wt % NaCl equiv.) but relatively gas rich (1-2 wt % $CO_2$), and are largely meteoric water. However, the contribution of magmatic components to the epithermal system, its temporal importance, and its relation to the source of ore metals are largely controversial. (omitted)

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Development of Sulfidation Resistant Amorphous Nb-Ni-Al-Si Coating Layer (내황화성 비정질 Nb-Ni-Al-Si 코팅층의 개발)

  • 이동복;김종성;백종현
    • Journal of the Korean institute of surface engineering
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    • v.30 no.4
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    • pp.248-254
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    • 1997
  • The sulfidation behavior of a sputter-deposited amorphous coating of 69.0%Nb-16.9Ni-11.9%Al-2.2%Si (at.%) has been investigated as a funtion of temperature.(973-1173K) in pure sulfur pressure of 0.01atm. The sulfidation kinetics of the casting obyed the parabolic rate low over the whole temperature ranges studied. The stlfidation rate increased with the temperature, as expected. The sulfide scale, the composition of which was $Al_2S_3,\;NbS_2,\;Ni_{3-x}S_2\;and\;FeCrS_4$, formed on the amorphous coating was primarily bilayered. Both the outer fastgrowing non-protective 4Al_2S_3$scale and the inner slowly-growing protective $NbS_2$,/TEX> scale and the inner slowly-growing protective $NbS_2$ scale had some Fe and Cr dissolution, which evidently came from the base substrate alloy of stainless steel type 304. Belows the coating, Kirkendall void formation was noticed. Nevertheless, a dramatic improvement of sulfidation resistance was achieved by sputter-depositing Nb-2 Ni-Al-Si layer on the stainless steel 304.

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Geophysical Survey in the Taran Area on the Central Kalimantan, Indonesia (인도네시아 중부 칼리만탄 타란지역에서의 물리탐사)

  • 조진동;김인준;박인화
    • Economic and Environmental Geology
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    • v.35 no.2
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    • pp.155-162
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    • 2002
  • There are many typical epithermal deposits scattering in the Taran of central Kalimantan. Indonesia. To get the shallow geological information, we carried out the geophysical exploration: spontaneous potential survey, in-suite magnetic susceptibility measurement and relistivity survey method in this area for a few weeks from September 30th to October 27th in 1997. SP survey (Fluke 27 multimeter)/magnetic susceptibility (EK -7 meter) measurement was carried out with a 250m$\times$10m lattice net in N45$^{\circ}$W direction. The dipole-dipole array resistivity survey was conducted with an electrode spacing of ${\alpha}$=30 m and electrode separation index n=7 at the line 5. The result shows that was the gold bearing quartz vein area can be divided into two type lone: low sulfidation type and high sulfidation type zone. The low resistivity value in the survey line 5 indicated a fracture Bone associated with the high sulfidation zone.

Low-Sulfidation Epithermal Gold Deposits in East China: Characteristics, Types, and Setting

  • Mao, Jing-Wen;Li, Xiao-Feng;Zhang, Zuo-Heng
    • Proceedings of the KSEEG Conference
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    • 2003.04a
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    • pp.15-18
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    • 2003
  • We preliminarily describe the basic characteristics of the low-sulfidation epithermal gold deposits in East China. It can be divided into granite- and alkaline rock-related types. These gold deposits are structurally controlled by caldera, craters, diatremes and related faults, hosted in volcanic rocks, and characterized by alterations of adularia, chalcedony, quartz, sericite and calcite assemblages. The ore-forming ages are within three pulses of 180-188 Ma, 135-141 Ma, and ca. 120 Ma, which are geodynamically corresponding the collision orogenic process between North China and Yangtze cratons, transformation of the tectonic regime, and delamination of the lithosphere, respectively.

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Sulfide treatment of HgCdTe substrate for improving the interfacial characteristics of ZnS/HgCdTe heterostructure (HgCdTe 기판의 황화 처리에 따른 보호막 특성 향상)

  • Kim, Jin-Sang;Yoon, Seok-Jin;Kang, Chong-Yoon;Suh, Sang-Hee
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2004.07b
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    • pp.973-976
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    • 2004
  • The results of numerous studies in III-V semiconductors show that sulfur treatment improves the electrical parameters of III-V compound devices. In this article, we examine the effects of sulfidation of HgCdTe surface on the interfacial characteristics of metal-ZnS-HgCdTe structures. Different from sulfidation in III-V material, S can not be act as an impurity because II-S compounds (ZnS, CdS) generally used as passivant for HgCdTe. Our studies of sulfur-treatment on HgCdTe surface show that sulfur agent forms the S- S, II-S bonds at the surface layer. These bonds are very effective to improve the electrical properties of ZnS layer on HgCdTe by reducing the possibility of native oxides formation. After the sulfidation process, MIS capacitors of HgCdTe show great improvement in electrical properties, such as low density of fixed charge and reduced hystereisis width.

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Mineralogical characteristics of Se- and Te-bearing epithermal gold-silver deposits: Eunsan and Moisan veins

  • Kim, Chang-Seong;Park, Seon-Gyu;Yoo, Bong-Chul;Kim, Wan-Joong;Jun-Rovillos
    • Proceedings of the KSEEG Conference
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    • 2003.04a
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    • pp.180-183
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    • 2003
  • Epithermal deposits are an important class of hydrothermal deposits, that have recently seen an surge of exploration and research, principally as significant resources of gold and silver. Epithermal deposits form at shallow depths (surface to 1-2km) and temperatures less than 30$0^{\circ}C$ (Hayba et al., 1985), and encompass a variety of low-sulfidation (near-neutral pH, reduced fluid; LS) and high-sulfidation (acidic and oxidized fluid; HS) deposits (Sillitoe, 1993; White and Hedenquist, 1995). (omitted)

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Hydrothermal Alteration and Its Cenetic Implication in the Casado Volcanic-hosted Epithermal Cold-Silver Deposit: Use in Exploration (가사도 화산성 천열수 금은광상의 열수변질대 분포 및 성인: 탐사에의 적용)

  • 김창성;최선규;최상훈;이인우
    • Journal of the Mineralogical Society of Korea
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    • v.15 no.3
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    • pp.205-220
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    • 2002
  • The gold-silver deposits in the Casado district were formed in the sheeted and stockwork quartz veins which fill the fault fractures in volcanic rocks. K-Ar dating of alteration sericite (about 70 Ma) indicates a Late Cretaceous age for ore mineralization. These veins are composed of quartz, adularia, carbonate, and minor of pyrite, sphalerite, chalcopyrite, galena, Ag-sulfosalts (argentite, pearceite, Ag-As-Sb-S system), and electrum. These veins are characterized by chalcedonic, comb, crustiform and feathery textures. Based on the hydrothermally altered mineral assemblages, regional alteration zoning associated with mineralization in the Gasado district is defined as four zones; advanced argillic (kaolin mineral-alunite-quartz), argillic (kaolin mineral-quartz), phyllic (quartz-sericite-pyrite) and propylitic (chlorite-carbonate-quartz-feldspar-pyroxene) zone. Phyllic and propylitic zones is distributed over the study area. However, advanced argillic zone is restricted to the shallow surface of the Lighthouse vein. Compositions of electrum ranges from 14.6 to 53.7 atomic % Au, and the depositional condition for mineralization are estimated in terms of both temperature and sulfur fugacity: T=245。$~285^{\circ}C$, logf $s_2$=$10^{-10}$ ~ $10^{-12}$ Fluid inclusion and stable isotope data show that the auriferous fluids were mixed with cool and dilute (158。~253$^{\circ}C$ and 0.9~3.4 equiv. wt. % NaCl) meteoric water ($\delta^{18}$ $O_{water}$=-10.1~8.0$\textperthousand$, $\delta$D=-68~64$\textperthousand$). These results harmonize with the hot-spring type of the low-sulfidation epithermal deposit model, and strongly suggest that Au-Ag mineralization in the Gasado district was formed in low-sulfidation alteration type environment at near paleo-surface.