• 한국광물학회지
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• 제26권3호
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• pp.161-174
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• 2013

원동지역은 스카른형 다중금속 광상으로서, 최근에는 회중석을 포함하는 텅스텐 광체의 유망광구로 주목받고 있다. 본 연구는 관입암체와 스카른 광물에 대한 연대측정을 통하여 스카른 형성 시기에 대한 지질연대학적 정보를 제공하고자 한다. 원동 지역의 층서는 석탄기와 트라이아스기, 캠브리아기와 오르도비스기의 층으로 이루어져있다. SHRIMP U-Pb 연대측정으로 원동지역 일대에 분포하고 있는 관입암류인 석영반암($79.37{\pm}0.94$ Ma)과 장석반암암맥($50.64{\pm}0.44$ Ma)의 정치고결시기를 결정하였다. K-Ar 연대측정으로 거정질의 금운모($49.1{\pm}1.1$ Ma), 괴상의 금운모($49.2{\pm}1.2$ Ma), 스카른광물과 공생하는 금운모($49.9{\pm}3.6$ Ma), 그리고 열수변질작용의 산물인 일라이트($48.3{\pm}1.1$ Ma)의 생성시기를 밝혀내었다. 열수 변질된 석영반암에서의 SHRIMP U-Pb 연대는 59.7~38.7 Ma까지 다양한 연대분포를 보이는데, 저어콘의 조직과 관련하여 메타믹티제이션(metamictization) 받은 저어콘 조직에서는 Pb 손실이 발생하여 연대 신뢰도가 떨어지는 반면, 용해-침전작용을 받은 부분의 연대 값은 동위원소 재평형 작용의 가능성이 있어 또다른 열수변질시기 혹은 화성활동시기에 대한 정보를 제공할 수 있다. 연대측정 결과와 광물 공생관계, 그리고 야외조사에서 확인된 석영반암 내 혹은 균열대에 발달해 있는 스카른용액 침투흔적으로 볼 때, 연구지역에서의 중석 스카른 광화시기는 약 50 Ma일 가능성이 높지만, 스카른 광체 선후관계 및 장석반암과 스카른 광체의 지질학적 연관관계에 대한 연구가 추가적으로 이루어져야 할 필요가 있다.

• 자원환경지질
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• 제47권4호
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• pp.317-333
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• 2014

선캄브리아기 경기육괴의 북서부에 위치한 포천 철(-동)광상은 다양한 이론이 제시되어 논쟁 대상이 되었으며, 성인적 측면에서 변성(-배기형) 퇴적 광상이 주된 생성이론으로 인지되었다. 본 논문에서는 포천 스카른화작용/철광화작용의 핵심 증거를 통하여 공간적으로 인접한 명성산 화강암이 관계화성암의 가능성을 제시하였다. 포천 스카른은 석회암과 백운암의 다양한 탄산염암을 모암으로 하여 Ca계열, Mg계열 및 Na-Ca계열 스카른이 형성되었다. 철광화작용은 주로 Na-Ca계열 스카른대를 따라 배태되고 있으며, 후퇴 스카른 단계에 국부적으로 동 광화작용이 중첩된다. 포천 후퇴 스카른 단계에 정출된 금운모의 Ar-Ar과 K-Ar연대측정 결과는 $110.3{\pm}1.0{\sim}108.3{\pm}2.8Ma$이며, 스카른 철(-동) 광화작용은 천부 관입암체인 명성산 화강암의 관입시기(112 Ma)와 일치하여 관계화성암으로 추정된다. 주변 탄산염암, 스카른 및 맥상의 탄산염광물간 산소-탄소 동위원소 빈화된 경향성은 개방계 조건($XCO_2=0.1$)에서 열수의 탈탄산염화 작용과 침투작용에서 유도되었다. 한편 황화광물(황동석-황철석 혼합물)과 경석고에서 매우 높은 황 동위원소 값은 황근원물질이 주변 탄산염암에 함유되어 있던 황산염광물로부터 공급되었을 가능성을 지시한다. 포천 광상 주변의 전단대에서는 파쇄대가 중첩되어 발달하여 있으며, 백악기 화강암으로부터 공급된 고온성 광화유체가 이러한 약선대를 따라 유입되어 약 $500^{\circ}{\sim}400^{\circ}C$의 온도범위에서 강력한 근지성 스카른화작용과 함께 광화작용이 유도되었다.

• 한국광물학회지
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• 제27권3호
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• pp.135-147
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• 2014

당두광상에서 산출되는 스카른 광물 및 섬아연석에 대한 분광분석을 실시하고 XRD 분석 및 편광현미경 관찰을 통해 휴대용 분광계를 이용한 스카른 광상 광물자원탐사에 있어서 효율성에 대해 고찰하였다. 그 결과, 단사휘석(회철휘석, 투휘석, 보통휘석), 석류석(회철석류석, 회반석류석), 녹렴석, 방해석, 녹니석 및 섬아연석이 산출됨을 확인하였으며, 단사휘석, 석류석, 녹렴석, 섬아연석의 경우 해당 광물의 단일표준분광정보와 매우 일치하는 반면, 녹니석은 방해석 및 단사휘석과 혼합된 형태의 분광특성이 나타난다. 분광특성분석과 XRD 분석 및 현미경관찰을 통한 교차검증 결과, 단사휘석, 석류석, 녹렴석의 경우 80% 이상의 일치성을 보인 반면, 섬아연석, 녹니석, 방해석의 경우 50% 이하의 일치성을 보인다. 따라서 휴대용 분광계를 이용한 스카른 광상 탐사 시 단사휘석, 석류석, 녹렴석의 정보제공에 효과적인 반면, 섬아연석, 녹니석, 방해석의 경우 부수적인 자료로 활용하는 것이 적절할 것으로 생각된다. 녹니석이나 방해석의 경우 효과적인 탐지를 위해서는 충분한 함량이 뒷받침되어야 할 것이다.

• 자원환경지질
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• 제19권1호
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• pp.1-18
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• 1986

A group of 16 $Zn+Pb{\pm}Ag$ deposits distributed in the Pyeongchang-Jucheon area, Kangwon-do, South Korea, were semi-regionally investigated. These deposits are contact metasomatic and/or hydrothermal replacement types hosted in the carbonate-dominated Cambrian Machari Formation and Ordovician Ibtanri Formation, and also in the carbonate interbeds of the Precambrian argillic metasediments. Comparing some key aspects of the individual deposits, it is found that the ore deposits hosted in the Machari and Ibtanri Formations are mostly of steeply-dipping chimneys with or without skarn minerals and are rich in Ag and Pb>Zn in metal grade whereas those occuring in the carbonate interbeds of the Precambrian argillic metasediments are gently-dipping conformable lenticular orebodies mostly with skarn minerals and are generally poor in Ag and Zn>Pb. The skarn mineralization in the area appears to have occurred during the lower Cretaceous (118.7Ma) to mid-Cretaceous (107.8Ma) time assumed from the K-Ar dates of the Dowon and Pyeongchang granites which are closely associated with the skarn ore deposits. The Rb/Ba/Sr ratios of these granites indicate that they are of strongly differentiated anomalous granites, and the Nb vs. Y and Rb vs. Y+Nb plots fall on the field of volcanic arc setting. The contact aureoles are zoned, giving the sequence in order of increasing distance from igneous contact: garnet-wollastonite, granet-wollastonite-clinopyroxene and garnet-clinopyroxene in such as the Pyeongchang and Yeonwol 114 areas. Electron microprobe analyses reveal that garnets and clinopyroxenes are generally low in Fe and Mn. Garnets are grossular to intermediate grandite except for those from the Ogryong exoskarn which are richer in andradite, pyrope and spessartine fractions. This indicates that the oxidation state of skarn-forming environment at Ogryong was higher than at the other deposits. Clinopyroxenes are mostly salitic except for those from the Ogryong exoskarn which involve considerable amounts of hedenbergite and johansenite fractions. The ${\delta}^{18}O$ value of Jurassic biotite granite at Ogryong is higher (+10.21‰) than that of Cretaceous one at Chodun (+8.41‰). The ${\delta}^{13}C$ values of carbonate rocks range from -0.89‰ to 0.68‰ and the ${\delta}^{18}O$ values range from +11.91‰ to + 19.34‰ indicating that these carbonate rocks are of marine origin. However, the ${\delta}^{13}C$ values of skarn calcite and vein calcite are -4.80‰ and -12.92‰, and the ${\delta}^{18}O$ values are +5.56‰ and +10.32‰, respectively, indicating that these calcites are of hydrothermal origin. The ${\delta}^{34}S$ values of sulfide minerals range from +4.4‰ to +8.7‰ suggesting that the sulfurs are of magmatic origin.

• 자원환경지질
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• 제29권4호
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• pp.411-419
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• 1996

The Janggun magnetite deposits occur as the lens-shaped magnesian skarn, magnetite and base-metal sulfide orebodies developed in the Cambrian Janggun Limestone Formation. The K-Ar age of alteration sericite indicates that the mineralization took place during late Cretaceous age (107 to 70 Ma). The ore deposition is divided into two stages as a early skarn and late hydrothermal stage. Mineralogy of skara stage (107 Ma) consists of iron oxide, base-metal sulfides, Mg-Fe carbonates and some Mg- and Ca-skarn minerals, and those of the hydrothermal stage (70 Ma) is deposited base-metal sulfides, some Sb- and Sn-sulfosalts, and native bismuth. Based on mineral assemblages, chemical compositions and thermodynamic considerations, the formation temperature, $-logfs_2$, $-logfo_2$ and pH of ore fluids progressively decreased and/or increased with time from skarn stage (433 to $345^{\circ}C$, 8.8 to 9.9 atm, 29.4 to 31.6 atm, and 6.1 to 7.2) to hydrothermal stage (245 to $315^{\circ}C$, 11.2 to 12.3 atm, 33.6 to 35.4 atm, and 7.3 to 7.8). The ${\delta}^{34}S$ values of sulfides have a wide range between 3.2 to 11.6‰. The calculated ${\delta}^{34}S_{H_2S}$ values of ore fluids are relatively homo-geneous as 2.9 to 5.4‰ (skam stage) and 8.7 to 13.5‰ (hydrothermal stage), which are a deep-seated igneous source of sulfur indicates progressive increasing due to the mixing of oxidized sedimentary sulfur with increasing paragenetic time. The ${\delta}^{13}C$ values of carbonates in ores range from -4.6 to -2.5‰. Oxygen and hydrogen isotope data revealed that the ${\delta}^{38}O_{H_2O}$ and ${\delta}D$ values of ore fluids decreased gradually with time from 14.7 to 1.8‰ and -85 to -73‰ (skarn stage), and from 11.1 to -0.2‰ and -87 to -80‰ (hydrothermal stage), respectively. This indicates that magmatic water was dominant during the early skarn mineralization but was progressively replaced by meteoric water during the later hydrothermal replacement.

• 자원환경지질
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• 제25권1호
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• pp.1-16
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• 1992

The Wondong Fe-Pb-Zn deposit is located in endo and exoskarns formed along the contact between the Makkol limestone interbedding pelitic limestone of Ordovician age and quartz porphyry of Cretaceous age. At the Wondong mine, the endoskarn shows a discontinuous zonal arrangement from quartz porphyry to pelitic limestone as follows: unaltered quartz porphyry, weakly altered quartz porphyry zone, intensively altered pinkish quartz porphyry zone, garnet zone, and greyish white and fine-grained clinopyroxene zone developed at pelitic limestone side. In terms of chemical mass balance, intensively altered pinkish quartz porphyry relative to unaltered quartz porphyry shows substantial enrichments in $K_2O$, $Na_2O$, and HREE and depletions in MgO, CaO, total $Fe_2O_3$, and LREE. On the other hand, garnet zone of endoskarn is enriched in CaO, MnO, total $Fe_2O_3$, MgO and depleted in $K_2O$, $Na_2O$. $Al_2O_3$ seems to be determining inert component. Thus the behavior of elements indicates that the mobility of elements depends on the equilibration of hydrothermal fluid and minerals and affects on enrichments by fractionation from and depletions by partition to hydrothermal fluid, respectively. Traversing toward pelitic limestone from a central zone of exoskarn, the exoskarn also shows a zonal arrangement as follows: garnet zone, clinopyroxene zone, and decolored pelitic limestone. The arrangement of mineral assemblages in skarns of the Wondong mine is the result of an increase in CaO and $K_2O$ toward the pelitic limestone. Skarn and ore minerals were formed in the following sequence: early skarn, late skarn and magnetite, pyrite, sphalerite, galena, and molybdenite. On the basis of stabilities of mineral assemblages, physicochemical conditions of the late skarn and magnetite mineralization are estimated to be $350^{\circ}C{\leq}T{\leq}400^{\circ}C$ at 1 Kb, $-23{\leq}log\;fO_2{\leq}-18$, and $0.005{\leq}XCO_2{\leq}0.01$, while those of the early skarn to be $420^{\circ}C{\leq}T{\leq}550^{\circ}C$ at 1 Kb.

• 자원환경지질
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• 제19권spc호
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• pp.3-17
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• 1986

Hundred mineral deposits including W-Mo, Pb-Zn-Cu, fluorite and talc occur in the Cambre-Ordovician limestone contacting with the Cretaceous Muamsa and Wolak granitoids in the Susanri-Hwanggangri mineralized zone. In most mineral deposits characterized by metasomatic replacement, skarn and hydrothermal vein types, two distinct tendencies were found as W-Mo mineralization in or/and near granitoid batholith and ($Pb-Zn-Cu(CaF_2)$) mineralization which is gradually increased toward the batholith. W-Mo veins of extensive vein system occupy northly striking fractures whilst $Pb-Zn-Cu-CaF_2$ veins strike northeast or northwest. In this work, three representative lead-zinc-copper deposits choosing the Dangdu, Useog and Eoksu mines were dealt with in detail. Skarn ore bodies in the Dangdu mine were grouped into early diopside rich clinopyoxene-garnet, barren skarn and ore bearing late hedenbergite rich clinopyroxene-garnet skarn. Temperature and $X_{CO_2}$, obtained from hedenbergite-andradite-calcite-quartz mineral equilibria in the Dangdu ore deposits were $580{\sim}650^{\circ}C$ and 0.15~0.3, respectively. Fluid inclusien evidence in the Useog mine indicates that main stage mineralization temperature ranges from 224 to $389^{\circ}C$ with a salinity of 2~17 equivalent wt. percent NaCl. Sphalerites from the Dangdu and Useog mines have 16~17.7 mole percent in FeS which is relatively consistent to those of some other lend-zinc ore deposits in South Korea. Filling tcmjCerature of fluid inclusion frem the Eoksu mine shows deposition of ore within the temperature ranges from 237 to $347^{\circ}C$ and within the salinity ranges from 2.6 to 10.77 equivalent wt. percent NaCl.

• 자원환경지질
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• 제31권4호
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• pp.277-290
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• 1998

The purpose of this research is to investigate the dispersion pattern of gold during skarnization and genesis of gold mineralization in the Sangdong skarn deposits. The Sangdong scheelite orebodies are embedded in the Cambrian Pungchon Limestone and limestone interbedded in the Myobong Slate of the Cambrian age. The tungsten deposits are classified as the Hangingwall Orebody, the Main Orebody and the Footwall Orebody as their stratigraphic locations. Recently, the Sangdong granite of the Cretaceous age (85 Ma) were found by underground exploratory drillings below the orebodies. In geochemisty, the W, Mo, Bi and F concentrations in the granite are significantly higher than those in the Cretaceous granitoids in southern Korea. Highest gold contents are associated with quartz-hornblende skarn in the Main Orebody and pyroxene-hornblende skarn in the Hangingwall Orebody. Also Au contents are closely related to Bi contents. This could be inferred that Au skarns formed from solutions under reduced environment at a temperature of $270^{\circ}C$. According to the multiple regression analysis, the variation of Au contents in the Main Orebody can be explained (87.5%) by Ag, As, Bi, Sb, Pb, Cu. Judging from the mineralogical, chemical and isotope studies, the genetic model of the deposits can be suggested as follows. The primitive Sangdong magma was enriched in W, Mo, Au, Bi and volatiles (metal-carriers such as $H_2O$, $CO_2$ and F). During the upward movement of hydrothermal ore solution, the temperature was decreased, and W deposits were formed at limestone (in the Myobong Slate and Pungchon Limestone). In addition, meteoric water influx gave rise to the retrogressive alterations and maximum solubility of gold, and consequently higher grade of Au mineralization was deposited.

• 자원환경지질
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• 제20권3호
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• pp.169-177
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• 1987

The Manjang copper magnetite-fluorite orebodies are imbedded within the limestone beds of the Hwajonri Formation. The ore deposits are characterized by magnetite-fluorite bearing skarn orebody in the west orebody and copper sulfide veins of the central and main orebodies. This study includes fluid inclusion geothermometry, salinity analysis, stable isotope analysis, and application of phase rule to mineral associations in skarn ore. Ore minerals are closely associated with the skarn silicates such as garnet, wollastonite and epidote. Magnetite and fluorite are remarkable in the west orebody whereas chalcopyrite is dominate in the central and main orebodies where pyrite and pyrrhotite also appear as sulfide gangues. Homogenization temperature and salinity of fluid inclusions are measured ranging between $240^{\circ}C$ and $350^{\circ}C$, 6.3~12.9 wt. percent in quartz and $220^{\circ}C$ and $350^{\circ}C$, 8.5~9.9wt. percent in fluorite, respectively. This indicates that the filling temperature and salinity are higher in quartz than in fluorite with the tendency of both to be linearly decreased suggesting an attribution of meteoric water to the mineralization. $T-fo_2$ diagram in the Ca-Fe-Si system at 1 kb and $Xco_2$=0.02 shows that the mineral assemblages with decreasing temperature are andradite-hedenbergite-calcite, hedenbergite-andradite-quartz, magnetite-andradite-quartz, and magnetite-quartz-calcite, indicating that magnetite crystallizes mostly late skarn stage at lower temperature. According to the carbon and oxygen isotopic values of the host limestone and calcite in ores, the sourec of carbon might be mixture of host limestone and deep seated carbons. Sulfur isotope data imply that ore fluids be relatively homogeneous in sulfur isotopic composition, mainly derived from igneous source.

• 한국광물학회지
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• 제23권3호
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• pp.211-217
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• 2010

스카른 Zn-Pb-Cu 복합광석을 구성하는 주요 구성 광물의 정량분석을 목적으로, 마이크로 포커스 X-ray 단층촬영 장비를 이용한 스카른 복합광석의 3차원 비파괴검사를 수행하였다. X-ray 단층화상의 화상결함을 감소시키고자 제안된 화상보정법을 이용하여 화상들을 보정한 후에 3차원으로 재구성하였다. 주사전자현미경(SEM)에 의한 표면분석과 보정된 X-ray 단층화상을 비교하여 주요광물에 대한 CT 값의 범위를 결정하였다. 재구성화상 내 전체 광물의 체적비율을 분석한 결과, 황화광물 20.5%, 맥석광물 79.5%로 평가되었다. X-ray 3차원 단층화상 정량분석법은 광석 내 유용광물의 부존형상과 회수율 분석에 유용하게 적용될 것으로 기대된다.