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RISS 인기검색어
- 검색키워드
- 저자 : Igor M. Villa (검색결과 2 건)
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Seo, Jung Hun,Yoo, Bong Chul,Villa, Igor M.,Lee, Jun Hee,Lee, Tongha,Kim, Chansu,Moon, Kun Ju Elsevier 2017 Ore geology reviews Vol.91 No.-
<P><B>Abstract</B></P> <P>The Sangdong scheelite–molybdenite deposit in northeast South Korea consists of strata-bound orebodies in intercalated carbonate-rich layers in the Cambrian Myobong slate formation. Among them, the M1 layer hosts the main orebody below which lie layers of F1–F4 host footwall orebodies. Each layer was first skarnized with the formation of a wollastonite + garnet + pyroxene assemblage hosting minor disseminated scheelite. The central parts of the layers were subsequently crosscut by two series of quartz veining events hosting minor scheelite and major scheelite–molybdenite ores, respectively. The former veins associate amphibole–magnetite (amphibole) alteration, whereas the latter veins host quartz–biotite–muscovite (mica) alteration. Deep quartz veins with molybdenite mineralization are hosted in the Cambrian Jangsan quartzite formation beneath the Myobong formation. In the Sunbawi area, which is in close proximity to the Sangdong deposit, quartz veins with scheelite mineralization are hosted in Precambrian metamorphic basement. Three muscovite <SUP>39</SUP>Ar–<SUP>40</SUP>Ar ages between 86.6 ± 0.2 and 87.2 ± 0.3 Ma were obtained from M1 and F2 orebodies from the Sangdong deposit and Sunbawi quartz veins. The Upper Cretaceous age of the orebodies is concordant with the published ages of the hidden Sangdong granite, 87.5 ± 4.5 Ma. This strongly suggests that the intrusion is causative for the Sangdong W–Mo ores and Sunbawi veins.</P> <P>Fluid inclusions in the quartz veins from the M1 and F2 orebodies, the deep quartz-molybdenite veins, and the Sunbawi veins are commonly liquid-rich aqueous inclusions having bubble sizes of 10–30 vol%, apparent salinities of 2–8 wt% NaCl eqv., and homogenization temperatures of 180–350 °C. The densities of the aqueous inclusions are 0.70–0.94 g/cm<SUP>3</SUP>. No indication of fluid phase separation was observed in the vein. To constrain the formation depth in the Sangdong deposit, fluid isochores are combined with Ti–in–quartz geothermometry, which suggests that the M1 and F2 orebodies were formed at depths of 1–3 km and 5–6 km below the paleosurface, respectively. The similarity of the Cs (cesium) concentrations and Rb/Sr ratios in the fluid inclusions of the respective orebodies indicate an origin from source magmas having similar degrees of fractionation and enrichment of incompatible elements such as W and Mo. High S concentrations in the fluids and possibly organic C in the sedimentary source likely promoted molybdenite precipitation in the Sangdong orebodies, whereas the scheelite deposition in the deep quartz–molybdenite veins hosted in the quartzite is limited by a lack of Ca and Fe in the hydrothermal fluids. The molybdenite deposition in the Sunbawi quartz–molybdenite veins hosted in the Precambrian metamorphic basement rocks was possibly limited by a lack of reducing agents such as organic C.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The Sangdong W–Mo orebodies were formed at 87 Ma. </LI> <LI> Magmatic–hydrothermal fluids including the Sangdong deposit and Sunbawi veins are derived from the same magma. </LI> <LI> W–Mo deposition from hydrothermal fluids is highly selective depending on the host rocks. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
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김영민(Yeongmin Kim),이인성(Insung Lee),James Farquhar,강지숙(Jisuk Kang),Igor M. Villa,김형범(Hyoungbum Kim) 대한지질학회 2021 대한지질학회 학술대회 Vol.2021 No.10
서울 지역 강수의 다중 황 동위원소(δ<SUP>34</SUP>Ssulfate, Δ<SUP>33</SUP>Ssulfate & Δ <SUP>36</SUP>Ssulfate), 질소 동위원소(δ<SUP>15</SUP>Nnitrate & δ<SUP>18</SUP>Onitrate) 및 스트론튬 동위원소(<SUP>87</SUP>Sr/<SUP>86</SUP>Sr)의 조성을 분석하였다. δ<SUP>34</SUP>Ssulfate 값은 1.9~14.6‰ (with a median of 4.7‰)의 범위를 보이며, δ<SUP>15</SUP>Nnitrate 값은 -2.0~13.3‰ (with a median of 1.0‰)의 범위를 보인다. 이러한 값은 화석연료의 사용이 황과 질소의 주요 공급원임을 지시하며, DMS 및 해수기원 황산염 등의 자연발생 공급원의 기여 역시 있었음을 확인할 수 있다. 겨울철에 높은 값을 보이는 δ<SUP>34</SUP>Ssulfate 및 δ<SUP>15</SUP>Nnitrate 값은 중국 지역에서 가정용 난방을 위해 사용되는 석탄의 사용 증가와 연관되어 있는 것으로 여겨진다. δ<SUP>18</SUP>Onitrate 값은 계절 변화를 보이며, 이는 NOx 산화 과정의 변화에 의한 것으로 생각된다. <SUP>87</SUP>Sr/<SUP>86</SUP>Sr 비는 0.70988~0.71487 (with a median of 0.71073)의 범위를 보이며, 최소 세 가지 공급원(규산염질 입자, 탄산염질 입자 및 인간활동 기원 물질)의 영향이 있었음을 지시한다.
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