• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.10 no.3
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• pp.145-153
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• 2005

I reviewed an ecological and environmental significance of microbial carbon respiration coupled to dis-similatory reduction of fe(III) to Fe(II) which is one of the major processes controlling mineralization of organic matter and behavior of metals and nutrients in various anaerobic environments. Relative significance of Fe(III) reduction in the mineralization of organic matter in diverse marine environments appeared to be extremely variable, ranging from negligible up to $100\%$. Cenerally, Fe(III) reduction dominated anaerobic car-bon mineralization when concentrations of reactive Fe(III) were higher, indicating that availability of reactive Fe(III) was a major factor determining the relative significance of Fe(III) reduction in anaerobic carbon mineralization. In anaerobic coastal sediments where $O_2$ supply is limited, tidal flushing, bioturbation and vegetation were most likely responsible for regulating the availability of Fe(III) for Fe(III) reducing bacteria (FeRB). Capabilities of FeRB in mineralization of organic matter and conversion of metals implied that FeRB may function as a useful eco-technological tool for the bioremediation of anoxic coastal environments contaminated by toxic organic and metal pollutants.

• Proceedings of the KSEEG Conference
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• 2000.04b
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• pp.266-267
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• 2000

• Economic and Environmental Geology
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• v.19 no.1
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• pp.57-66
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• 1986

The ore deposit of the Ohtani mine is one of representatives of plutonic tungsten-tin veins related genetically to acidic magmatism of Late Cretaceous in the Inner zone of Southwest Japan. Based on macrostructures of vein filling, three major mineralization stages are distinguished by major tectonic breaks. The constituents of ore minerals are scheelite, cassiterite, chalcopyrite, pyrrhotite, sphalerite, with small amounts of cubanite, stannite, galena, native bismuth, bismuthinite, arsenopyrite and pyrite. The relationship between the polymorphic variations of pyrrhotite and the kinds of the associated characteristic of ore mineral, in relation with hypogene mineralization, has been demonstrated. Pyrrhotite of stage I is predominantly of the hexagonal phase (Hpo>Mpo). Pyrrhotite of stage II is mainly of the monoclinic phase ($Hpo{\ll}Mpo$). Pyrrhotite of stage III is a single monoclinic phase ($Hpo{\ll}Mpo$). The compositions of the hexagonal pyrrhotite decrease in Fe content ranging from 47.44 atom % Fe in stage I to 46.88 atom % Fe in stage III.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.10 no.1
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• pp.38-46
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• 2005

This study was carried out to quantify the rates of anaerobic mineralization and sulfate reduction, and to discuss the potential effects of benthic fauna on sulfate reduction in total anaerobic carbon respiration in Ganghwa intertidal flat in Korea. Anaerobic carbon mineralization rates ranged from 26 to 85 mmol $C\;m^{-2}\;d^{-1}$, which accounted for approximately 46 tons of daily organic matter mineralization in the intertidal flat of southern part of the Ganghwa Island (approximately $90\;km^2$). Sulfate reduction ranged from 22.6 to 533.4 nmol $cm^{-3}\;d^{-1}$, and were responsible for $31{\sim}129%$ of total anaerobic carbon oxidation, which indicated that sulfate reduction was a dominant pathway for anaerobic carbon oxidation in the study area. On the other hand, the partitioning of sulfate reduction in anaerobic carbon mineralization in October decreased, whereas concentrations of Fe(II) in the pore water increased. The results implied that the re-oxidation of Fe(II) in the sediments is stimulated by macrobenthic activity, leading to an increased supply of reactive Fe(II), and thereby increasing Fe(III) reduction to depress sulfate reduction during carbon oxidation.

• Economic and Environmental Geology
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• v.51 no.6
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• pp.493-507
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• 2018

The Wooseok deposit in Jecheon belongs to the Hwanggangri Mineralized Distict of the northeastern Ogcheon Metamorphic Belt. Its geology consists mostly of limestone of the Choseon Supergroup and the Cretaceous Muamsa granite intruded at the eastern area of the deposit. The deposit shows vertical occurrence of skarn and hydrothermal vein ores with W-Mo-Fe and Cu-Pb-Zn mineralization and skarn is developed only at lower levels of the deposit. Skarn minerals are replaced or cut by ore minerals in paragenetic sequence of magnetite-hematite, molybdenite-scheelite-wollframite, and higher abundances of pyrrhotite-chalcopyrite-pyrite-sphalerite-galena. Garnet has chemical compositions of $Ad_{65.9-97.8}Gr_{0.3-32.0}Pyr_{0.9-3.0}$, corresponding to andradite series, and pyroxene compositions are $Hd_{4.5-49.7}Di_{42.3-93.9}Jo_{0.5-7.9}$, prevailing in diopside compositions, both of which suggest oxidized conditions of skarnization. On the FeS-MnS-CdS ternary diagram, FeS contents of sphalerite in vein ores decrease with increasing MnS contents from bottom to top levels, possibly relating to W mineralization in deep and Pb-Zn mineralization in shallow level. Sulfur isotope values of sulfide minerals range from 5.1 to 6.8‰, reflecting magmatic sulfur affected by host rocks. W-Mo skarn and Pb-Zn vein mineralization in the Wooseok deposit were established by spatio-temporal variation of decreasing temperature and oxygen fugacity with increasing sulfur fugacity from bottom to top levels.

• Proceedings of the KSEEG Conference
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• 2003.04a
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• pp.178-179
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• 2003

Mesothermal, tellurium-bearing gold-silver vein mineralization of the Yuryang mine was formed in mineralogically complex quartz-sulfide veins that filled the fault fractures in Precambrian gneiss within Gyeonggi Massif. Ore grades average 179 g/ton gold with a gold/silver ratio of 1.5 : 1. Ore mineralization was deposited in single stage. Major ore mineralization can be divided into two mineralization phases with increasing paragenetic time: Fe-sulfide and base-metal mineralization phase $\rightarrow$ telluride mineralization phase. (omitted)

• Economic and Environmental Geology
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• v.34 no.4
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• pp.319-328
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• 2001

The Fe-REE deposit of the Hongcheon-Jaeun district occurs in Precambrian gneiss, and is classified into two ore bodies: the Jaeun ore body (northern ore body) and the Hongcheon ore body (southern ore body). Ecomonically important minerals consist of magnetite, monazite, strontianite and barite. Based on mineral assemblages and textures, the mineralization can be classified into two stages (Na-carbonatite stage and Fe-carbonatite stage). Main REE minerals were precipitated during the Fe-carbonatite stage. Some evidences of the carbonatite origin include: 1) strontianite-monazite exolution texture, 2) strontianite-barite exolution texture, 3) the occurrence of acmite of igneous origin at the area with abundant rare earth minerals, 4) the occurrence of the mineral assemblage consisting of carbonate minerals + magnetite + REE minerals. Therefore, we suggest that Fe-REE mineralization in the study area was related to carbonatite of igneous origin.

• Economic and Environmental Geology
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• v.15 no.4
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• pp.189-204
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• 1982

The Geodo mine is located in the southern limb of the Hambaeg syncline. Geology of the area consists of Paleozoic-Mesozoic sedimentary Rocks and Cretaceous igneous rocks. The important igneous rocks presumably related to skarnization and ore mineralization in the area, are the early granodiorite and the late porphyritic granodiorite. Two mineralogical types of ore deposits are recognized in the area. They are the Fe-Cu deposits in the Myobong formation and the Au-Bi-Cu deposits in the Hwajeol formation. Contact metamorphism due to granodiorite intrusion includes hornfelsization, exoskarnization and endoskarnization. Wall-rock alterations related to the Fe mineralization are grouped into the hydrothermal replacement skarnization and the hydrothermal filling skarnization. Another hydrothermal alteration is associated with the Cu mineralization. Various mineralogical analyses have been applied for the identification of minerals. They include optical microscopy, chemical analysis, etching test, X-ray diffraction, and infrared absorption spectroscopic analyses. The ore minerals in these ore deposits are classified into two groups;hypogene and supergene minerals. Hypogene minerals consist of magnetite, pyrite, chalcopyrite, and chalcocite. Supergene minerals consist of chalcocite, bornite, and geothite. Ore minerals show various kinds of ore texture: open-space filling, exsolution, replacement, and cementation texture. The gangue minerals consist of quartz, diopside, epidote, garnet and plagioclase in the hornfelsic zone, garnet, diopside, scapolite, actinolite, sericite, chlorite, quartz, and calcite in the skarn zone, and, epidote, chlorite, sericite, quartz, and calcite in the late hydrothermal alteration zone. This study shows that the Fe-Cu deposits are of metasomatic pipe type with the later hydrothermal fillings, and the Au-Bi-Cu deposits are of hydrothermal fissure-filling type. The mineralization is probably related to the intrusion of porphyritic granite.

• Economic and Environmental Geology
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• v.20 no.1
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• pp.61-75
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• 1987

The Daejang mine is one of the representatives of Cu-Pb-Zn-(Ag) vein deposit related genetically to late Cretaceous granitoid in Korea. Sericite from an alteration halo of the mine yielded a K-Ar date of $95{\pm}3.5Ma$. Based on macrostructures of vein filling, three major mineralization stages (I, II and III) are distinguished by tectonic breaks. Major ore constituents are arsenopyrite, pyrite, pyrrhotite, sphalerite, chalcopyrite, galena, boulangerite, with small amounts of Ag-bearing tetrahedrite, pyrargyrite, native bismuth, marcasite, siderite, ankerite, gudmundite and calcite. Characteristic feature of each mineralization stage and compositional variation of sphalerite and arsenopyrite are discussed in relation to the genetic environments. The FeS contents of sphalerites are 20.5~14.9 mole % in stage I, 17.9~11.9 mole % in stage IIA, 17.0~9.2 mole % in stage IIB, and 6.9~4.7 mole % in stage III. Their results are indicative of decreasing FeS contents during mineralization process in sphalerite coexisting with sulfur-rich sulfide assemblages, such as monoclinic pyrrhotite and pyrite, and is agreement with the conclusions shown by Scott and Kissin(1973). The composition of arsenopyrite decrease also in As content from stage I to stage III, and the compositional variation correlate with position of the associated minerals in the paragenesis. Temperature and pressure of the mineralization are determined as $250{\sim}430^{\circ}C$ and 4.0~0.3kb respectively, based on the chemistry of the minerals.

• Journal of the Mineralogical Society of Korea
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• v.19 no.4 s.50
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• pp.325-336
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• 2006

Domestic serpentinite is one of the important industrial minerals utilizing in the iron manufacturing company such as POSCO in Korea. Serpentinite is distributed in the Ulsan Fe deposit, Andong, Hongseong-Cheongyang, and Gapyeong areas. This study tries to interpret the relationship among the formation of carbonate rocks, iron mineralization, and serpentinite alteration throughout the study of field occurrence, mineralogy, and chemical compositions. Serpentine is formed by the break-down of olivine and pyroxene of parent peridotite. The serpentinization is inferred to be formed by the hydrothermal fluid derived from intruded Cretaceous granite and the addition of meteoric water. Variation of major oxides such as $SiO_2,\;Fe_2O_3$, and MgO in serpentinized rocks are controlled by the degree of serpentinization and Fe mineralization. Variation of $Al_2O_3$ and CaO contents of altered rocks is dependent on the amount of the residual minerals such as calcite and homblende, and on the degree of chloritization. The presence of carbonate rocks reported in the sedimentary origin or igneous origin (carbonatite) provided a geological environment to form skarn type Fe deposit regardless of its origin. The geological processes of Ulsan Fe deposits are inferred to be formed as the order of the formation of carbonate rocks ${\to}$ the intrusion of Cretaceous granite ${\to}$ serpentinization ${\to}$ Fe mineralization by the interprelation of field occurrence and mineralogical characteristics.