• Journal of the Mineralogical Society of Korea
• /
• v.32 no.1
• /
• pp.71-77
• /
• 2019

New geochronological data of U-Pb, Re-Os and the lead isotope analysis of the Cu-Mo-Au mineral deposits are reported in the Trapiche and Constancia around Apurimac province, southeastern part of Peru. The measured ages were the first regional pulse of previously reported mineralization age between 28 and 33 Ma. The lead isotopic results indicate two sources of mineralization. The first source is thought to be derived from the upper crust and the second one is thought to be derived from a mixture of the upper crust and the lower crust.

• Korean Journal of Mineralogy and Petrology
• /
• v.34 no.1
• /
• pp.57-67
• /
• 2021

The geology of the Iskaycruz project are mainly composed of sedimentary rocks within Cretaceous basin. The basal part is composed up of dark-gray shale, gray sandstone, and clastic rock of Oyon formation interbedded with coal measures. In the folded zone in the eastern part of the survey area, there is Chimu formation that has medium-grained massive and white quarztite. In terms of geological structure, the Iskaykruz region is located in the folded and overthrust zones of the central part of the Occidental Mountains. Ore body was formed by hydrothermal replacement process and consists of zinc, lead, silver, and copper. Stratabound-type deposits are hosted in limestone of Santa formation. It extends 12 kilometers discontinuously from northern Canaypata to southern Antapampa. Irregular iron oxide and sulfide minerals hosted in Santa and Parihuanca formations are observed. The mineralization observed on the surface consist of primary sulfides consisting of sphalerite with galena and chalcopyrite, and iron and manganese oxide produced from oxidation of primary sulfides. Skarn minerals are accompanied by tremolite, garnet, epidote and quartz.

• Economic and Environmental Geology
• /
• v.43 no.3
• /
• pp.235-248
• /
• 2010

To construct the standard methods for evaluation of physicochemical characteristics of tailings in Korea, specific gravity, paste pH, grain size, mineral compositions and heavy metal concentrations of total 26 tailings from 21 metallic mines were analyzed. Specific gravity of tailings ranged from 2.61 to 4.31 (avg. 3.04), and sand and silt grain were dominant in the tailings. Ranges of paste pH were 2.1-9.5 in tailings (7.1-9.2 at magmatic, skarn and hydrothermal replacement deposits and 2.1-9.5 at hydrothermal vein deposits). Additionally, hydrothermal vein deposits could be reclassified into three categories: (1) paste pH>7.0, (2) 4.0

• Economic and Environmental Geology
• /
• v.11 no.4
• /
• pp.127-141
• /
• 1978

The major structures characteristic of the Taebaegsan sedimentary basin were regionally analyzed with special reference to its southeastern extension to the Yeonhwa-Ulchin district of economic interest in zinc-lead mineralization. The basin geometry, basement setting, sedimentary components, and the characteristics of deformation and igneous activity of the Taebaegsan basin differ basically from those of the adjacent mobile belt of the Ogcheon geosyncline, although the latter affected the basin's western side considerably. The subrectangular shape of the Taebaegsan basin reflects the checkered pattern of basement-block arrangement, and the carbonate-dominated lithologic components of the basin-fill indicate a cratonic depositional setting, which is comparable to some of the North American mid-continental craton. The Taebaegsan basin, however, has somewhat been less stable than the North American megacraton that is reflected in the former's thicker sedimentary fill and steeper faults of later deformation, showing a tendency to increase in thickness close to the basement-block boundaries, which may indicate contacts of possibly detached cratonic blocks of Precambrian age; these weak zones of block boundaries have been the loci of repeated sedimentation, deformation and related igneous intrusions. A series of downthrown or uplifted tilted blocks, in which the Cambro-Ordovician sedimentary wedges and the late Cretaceous to early Tertiary igneous intrusives are involved, occurs intermittently across the Yeonhwa-Ulchin district in a noticeable pattern of en echelon type. These sedimentary wedges are correlated to the Cambro-Ordovician section of the Hambaeg syncline to the west in stratigraphy and lithology, and are considered to have resulted from the northeastern and/or northwestern cross-faulting of the pre-existing syncline belt of easterly trend, extended from the main portion of the Hambaeg syncline. These structural junctions (or intersections) of the earlier syncline belt and the later cross-faults have been acted as a guide to ascending igneous materials and hydrothermal ore-forming fluids to form a zone of zinc-lead skarn deposits across the Yeonhwa-Ulchin district showing a stepwise recurrence of these deposits toward the east.

• Economic and Environmental Geology
• /
• v.48 no.1
• /
• pp.1-13
• /
• 2015

The geology of the Seungryung Zn deposit, located in the Muzu basin, consists of Precambrian leucocratic granitic gneiss, Cretaceous clastic rocks, pyroclastic rocks, and intrusive rocks. The deposit shows a weakly skarnized hydrothermal replacement ore developed along limestone bed in the gneiss. The mineralization can be divided into three stages: the early skarnization producing garnet and pyroxene, the main mineralization in the middle stage precipitating most metallic minerals such as magnetite, sphalerite, chalcopyrite, pyrrhotite, Pb-Ag-Bi-S system minerals, and the late stage for altered or low temperature minerals such as chlorite and marcasite. Pb-Ag-Bi-S system minerals include heyrovskite-eskimoite solid solution, lillianite-gustavite solid solution, and vikingite. Chalcopyrite diseases are quite common in sphalerite showing bead chains and dusting textures. The ${\delta}^{34}S$ values of sulfides minerals are concentrated within the narrow range of 3.4~4.1‰ for pyrite, 3.3~4.3‰ for sphalerite, 4.0~4.3‰ for chalcopyrite, and 2.8‰ for galena, suggesting that most sulfur is of igneous origin. Sulfur isotope geothermometry is calculated to be $346{\sim}431^{\circ}C$, implying that the mineralization occurred at relatively high temperature. FeS contents of sphalerite are relatively high in the range of 6.58~20.16 mole% (avg. 16.58 mole%) with the enrichment of Mn compared to Cd, similarly to representative skarn Pb-Zn deposits in South Korea. On the contrary, sphalerite from Au-Ag deposits in the Seolcheon mineralized zone around the Seungryung deposit is enriched in Cd, showing similar feature like representative epithermal Au-Ag deposits. This suggests that around the related igneous rocks, magnetite and sphalerite were produced at high temperature in the Seungryung deposit, and with decreasing temperature and compositional change of mineralizing fluids, Au-Ag mineralization proceeded in the Seolcheon mineralized zone.

• Economic and Environmental Geology
• /
• v.20 no.3
• /
• pp.179-196
• /
• 1987

Various skarn ore deposits of Pb-Zn, Fe-Cu, W-Mo and others are widely distributed in the study area which consists mainly of Cambro Ordovician calcareous rocks. The ore deposits are all in close association with specific types of granitic rocks of mid-late Cretaceous age according to the kinds of ores: Fe-Cu deposit with granodiorite-quartz monzodiorite, Pb-Zn deposit with granite-granodiorite, W-Mo deposit with granite, and Mn deposit with quartz porphyry. The granitic rock of Fe-Cu deposit has lower content in K and higher in Ca than those of Pb-Zn deposits. On the contrary, the granitic rock of W-Mo deposit has much higher content in K and lower in Ca in comparison to those of Pb-Zn deposits. However, the granitic rock of Mn deposit shows similar variation to those of Pb-Zn deposits. Lithophile trace elements of Sr and Rb tend to vary in close relation with major elements of K and Ca, respectively. In good contrast, chalcophile elements of Cu, Pb, Zn, Wand Mo are enriched in the granitic rocks of their ore deposits, and other trace elements of Ni and Co show a trend to vary in relation with Mg, Fe and Cu, which have the same replacement index (0.14) as Ni and Co. Average K/Rb and Ca/Sr ratios of the granitic rocks range nearly within 300~150 and 150~40, respectively, and the distribution pattern of the ratios is different according to the kind of ore deposits: Fe-Cu deposit is plotted toward K-Rb poor region whereas Pb-Zn and W-Mo deposits toward K-Rb rich region. In contrast, Fe-Cu and Fe deposits are plotted toward Ca-Sr rich region whereas Pb-Zn deposit toward Ca-Sr poor region. The variation trend of chemical elements of the mid-late Cretaceous granitic rocks in the study area is similar to that of the Cretaceous granitic rocks in the Gyeongsang Basin. Therefore, this geochemical result may be applicable to determining what kinds of ore deposits a Cretaceous granitic rock is favourable for, and whether it is productive or non-productive for systematic geochemical exploration works.

• Economic and Environmental Geology
• /
• v.44 no.4
• /
• pp.313-320
• /
• 2011

The Taebaegsan Mineralized District is the most prospective region for the useful mineral commodities such as a coal, non-metallic, metallic mineral in South Korea. From a general point of view, Cambro- Ordovician limestone formations, Myobong slate and Pungchon (Daegi) limestone, are the most fertilizable formations in the Taebaegsan Mineralized District. The geology around Weondong mine area consists mainly of Carboniferous-Triassic formations and Cambro-Ordovician formations intruded by rhyolite/quartz porphyry. The great overthrusted fault of N40~$50^{\circ}E$ direction, so called Weondong overthrust fault, is observed in the central part of the mine area and the NS fault system cuts the overthrusted fault. By postulating from the favorable geological and structural condition around Weondong area, the possibility of deep seated hidden ore bodies is expected. In 2010, on the basis of the results of LOTEM and CSAMT survey, the cross-hole survey was performed for the investigation of the hidden polymetallic ore body in the deep parts of the Weondong mine area and the grade of the newly-discovered orebody is as follows; (1) The cut-off grade for lead-zinc 3%; an weighted average grade 5.50% (2.7 m), (2) The cutoff grade for copper 0.1%; an weighted average grade 0.91% (14.65 m), (3) The cut-off grade for iron 30%; an weighted average grade 38.18% (3.3 m), (4) $WO_3$ for each cut-off grade(0.01%, 0.05%, 0.1%); an weighted average grade 0.29 wt. % (8.8 m), 1.15 wt. % (2.1 m), 1.97 wt. % (1.2 m), (5) $MoS_2$ for each cut-off grade(0.01%, 0.1%); an weighted average grade 0.15 wt. % (6.3S m), 0.28 wt. % (3.15 m), (6) $Ta_2O_5$ for each cut-off grade (0.01%, 0.1%); an weighted average grade 0.13% (19.S m), 1.11% (1.8 m), (7) $Nb_2O_5$ for each cut-offgrade (0.01%, 0.1%); an weighted average grade 0.06% 11.5 m), 0.15% (3.0 m).

• Economic and Environmental Geology
• /
• v.40 no.5
• /
• pp.517-535
• /
• 2007

Two distinctive Mesozoic hydrothermal systems occurred in South Korea: the Jurassic/Early Cretaceous(ca. $200{\sim}130$ Ma) deep-level ones during the Daebo orogeny and the Late Cretaceous/Tertiary(ca. $110{\sim}45$ Ma) shallow hydrothermal ones during the Bulgugsa event. The Mesozoic hydrothermal system and the metallic mineralization in the Korean Peninsula document a close spatial and temporal relationship with syn- to post-tectonic magmatism. The calculated ${\delta}^{18}O_{H2O}$ values of the ore-forming fluids from the Mesozoic metallic mineral deposits show limited range for the Jurassic ones but variable range for the Late Cretaceous ones. The orogenic mineral deposits were formed at relatively high temperatures and deep-crustal levels. The mineralizing fluids that were responsible for the formation of theses deposits are characterized by the reasonably homogeneous and similar ranges of ${\delta}^{18}O_{H2O}$ values. This implies that the ore-forming fluids were principally derived from spatially associated Jurassic granitoids and related pegmatite. On the contrary, the Late Cretaceous ferroalloy, base-metal and precious-metal deposits in the Taebaeksan, Okcheon and Gyeongsang basins occurred as vein, replacement, breccia-pipe, porphyry-style and skarn deposits. Diverse mineralization styles represent a spatial and temporal distinction between the proximal environment of subvolcanic activity and the distal to transitional condition derived from volcanic environments. The Cu(-Au) or Fe-Mo-W deposits are proximal to a magmatic source, whereas the polymetallic or the precious-metal deposits are more distal to transitional. On the basis of the overall ${\delta}^{18}O_{H2O}$ values of various ore deposits in these areas, it can be briefed that the ore fluids show very extensive oxygen isotope exchange with country rocks, though the ${\delta}D_{H2O}$ values are relatively homogeneous and similarly restricted.

• Economic and Environmental Geology
• /
• v.51 no.6
• /
• pp.473-483
• /
• 2018

Green-blue coloured supergene minerals are covering host rocks along the gallery wall in the Gukjeon mine, a lead - zinc skarn deposit located in Miryang, Gyeongsangnam-do. These minerals have been described as azurite or malachite, but recent study recognized that the green minerals are devilline and blue minerals are Cu-Zn hydrated sulfates, but exact identification and detailed mineral characteristics are also not well known. In this study, we divide green-blue minerals into five groups (GJG) according to their external features and conducted XRD and SEM analyzes in order to identify mineral name and clarify the mineralogical characteristics. GJG-1, a bright bluish green group, consists of brochantite and quartz and GJG-2, a pale green colour with easily crumbly, of schulenbergite and a small amount of gypsum. Although pale blue GJG-3 and glassy lustrous bluish green GJG-4 have the same mineral assemblages with serpierite and gypsum in spite of different colour and luster, gypsum content may control the physical properties. GJG-5 with a gel phase mixture of pale blue and dark blue mineral is comprised of hydrowoodwardite, glaucocerinite, bechererite, serpierite and gypsum. The six green-blue minerals from the Gukjeon mine could be classified by Cu:Zn ratio, (Si + Al) content, Si:Al ratio, and Ca content. The physico-chemical environment of mineral formation is considered to be controlled by the geochemical factors in the surrounding fluid, and it looks forward that the accurate formation environment will be revealed through additional research. This paper gives greater mineralogical significance in the first report of several hydrated sulfate such as serpierite, glaucocerinite and bechererite in Korea. It has also rarely been reported the occurrence of several Cu-Zn hydrated sulfate in the same deposit in the world.