By Sergey M. Rodionov1, Alexander A. Obolenskiy2
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|  Yüklə 2.21 Mb.
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Wolak Metallogenic Belt ofPolymetallic Pb-Zn Vein, W±Mo±BeSkarn, W-Mo-Be Greisen, Stockwork,and Quartz Vein, Cu (±Fe, Au, Ag, Mo)Skarn, Fe Skarn, and Weathering CrustFe Deposits(Belt WO) (South Korea)This metallogenic belt is hosted in the Cambrian and Ordovician Great Limestone Group, Ogcheon Group and terrane, and Proterozoic Gyenggi terrane of the South China (Yangzi) Craton, and in the Jurassic Daebo Granite. These units are intruded by the Cretaceous Bulgugsa granite. The age the belt is interpreted as Cenomanian through Campanian with K-Ar isotopic ages of 96 to 75 Ma. The Gyeonggi Gyenggi terrane consists mostly of metasedimentary rock iincluding chlorite-sericite-quartz schist and hornblende-biotite-gneiss. The Ogcheon Group consists of slate, calc-silicate and granitic gneiss. The Cretaceous Bulgugsa granite consists of biotite granite, leucogranite, and hornblendite. The major deposits are at Wolak, Susan, Jesamuk, and Youngdeog. Wolak W-Mo-Be Greisen, Stockwork, and Quartz Vein DepositThe deposit (Kim and Koh, 1963) consists of fissure filling pegmatitc quartz veins that strike N20oE and dip 85 to 90o southeastern in the calc-silicate rock, cordierite-biotite hornfels, and biotite granite. The ore minerals consist of wolframite, scheelite, bismuthinite, chalcopyrite, pyrite, galena, and sphalerite. The host rocks are mainly calc-silicate rock and slate that are intruded by leucogranite and hornblendite. In underground tunnels, the veins occur in sygmoid curves, and in shingle and horsetail patterns. The deposit is small with an average grade of 2% WO3, 0.6% MoS2. Susan Fe Skarn MineThis mine (Kim and Kim, 1962) consists of Cambrian and Ordovician limestone that is intruded by Cretaceous biotite granite. Both limonite and Mn deposit occur. The limonite part of the deposit occurs sporadically in limestone in masses or layers between terraossa and limestone, or in limestone. The Mn part of the deposit occurs in veins in limestone. The veins pinch out at depth. The limonite is interpreted as a residual deposits, and the Mn deposit is interpreted as a hydrothermal deposit. The deposit is small resources of 338,450 tonnes Fe, and 3,171 tonnes Mn grading 50.95% Fe, 34.84% Mn. Jesamuk Cu (±Fe, Au, Ag, Mo) Skarn MineThis mine (Moon and Cho, 1965.) consists of sulfide skarn in limestone of the Cambrian and Ordovician Great Limestone Series that is intruded by biotite granite of the Cretaceous Bulgugsa Series. The limestone bedding generally strikes N20 to 30oE and dips 20 to 30o northwest. The deposit is interpreted as a pocket type, hydrothermal sulfide replacement in limestone. The sulfides are mainly galena, sphalerite, chalcopyrite, arsenopyrite, pyrrhotite, and pyrite. Gangue minerals are calcite, fluorite, and quartz. The mine is small with reserves of 135,000 tonnes ore; indicated reserves of 35,000 tonnes; and resources 100,000 tonnes. Grades range from 0.18-2.05% Cu, 1.44-6.54% Pb, 2-3.01% Zn, 30.7-843.4 g/t Ag. Youngdeog Polymetallic Pb-Zn ± Cu (±Ag, Au) Vein and Stockwork DepositThis deposit (Oh and Kim, 1980) is hosted in the Proterozoic Ogcheon Group granitic gneiss that is intruded by Cretaceous granite, leucocratic granite, and intermediate composition dikes. A conjugate joint pattern is common in the leucocratic granite with joints striking N30oW, dipping 75o southwest and N 48oE dipping 83oSE. The deposit consists of hydrothermal sulfides in disseminations that occur in an altered zone in leucocratic granite. The sulphide minerals are galena and sphalerite with Au and Ag, and other sulphide minerals such as pyrite and chalcopyrite. The most common hydrothemal alteration, especially at shallow depth, is softening and bleaching of the leucocratic granite. The deposit is small with reserves of 100,000 tonnes ore. Average grade is 0 .4-4.0 g/t Au, 149-488 g/t Ag, 1.26-5.31% Pb, 3.99-13.9% Zn. Origin and Tectonic Controls for Wolak Metallogenic BeltThe belt is interpreted as forming during generation of granitoids during the Late Cretaceous to Early Tertiary Bulgugsa orogeny. The deposits formed during intrusion of Cretaceous Bulgugsa granite (biotite granite, leucogranite, and hornblende granite). The belt is hosted hosted in the Proterozoic Gyenggi terrane of the South China (Yangzi) Craton, that contains the Ogcheon Group, and in the Cambrian and Ordovician Great Limestone Group, and Jurassic Daebo Granite that are intruded by the Cretaceous Bulgugsa granite. REFERENCES: Kim and Kim, 1962; Kim and Koh, 1963; Moon and Cho, 1965; Oh and Kim, 1980; Duk Hwan Hwang, this study Gyeongpuk Metallogenic Belt ofPolymetallic Pb-Zn Cu (Ag, Au) Veinand Stockwork, W-Mo-Be Greisen,Stockwork, and Quartz Vein, Sn-W Greisen,Stockwork, and Quartz Vein, Fe Skarn,and Polymetaliic Ni Vein Deposits(Belt GP) (South Korea)This metallogenic belt is hosted in the Yeongnam Metamorphic Complex, Gyeongsang Supergroup, Yeongnam granulite-paragneiss terrane, that is part of the Sino-Korean Craton, and in the Late Cretaceous Bulgugsa Granite. The age range of the belt is interpreted as Cenomanian through Campanian (96 to 75 Ma). The Yeongnam Metamorphic Complex consists of leucogranite gneiss, hornblende plagioclase gneiss, and biotite gneiss and schist of the Wonnam Formation. The Gyeongsang Supergroup consists of shale and sandstone of Hadong and Sindong Group and volcanic rock of Yucheon Group. The Bulgugsa Granite consists of biotite granite, granodiorite, anorthosite, porphyry, and felsic and quartz porphyry dikes. The major deposits are at Darak, Kyeongju, Chilgok, and Wangpiri. Darak Polymetallic Pb-Zn Cu (Ag, Au) Vein and Stockwork DepositThis deposit (Cho and Lee, 1966) is hosted in Precambrian granite gneiss and Cretaceous biotite granite and granodiorite that are intruded by Late Cretaceous porphyry, felsite and quartz porphyry dikes. The deposit consists of sulfide veins in hydrothermal fissure fillings in granite gneiss, granodiorite, and biotite granite. The main vein strikes N50-60° W, dips 70-90° southwest, and averages 70 cm wide. Average grade is 3.57% Pb, 3.72% Zn. The ore minerals are galena, sphalerite, pyrite, pyrrhotite, and chalcopyrite. Gangue minerals are quartz, feldspar, calcite, chlorite, sericite, and fluorite. The deposit is small with resources of 85,720 tonnes ore. Average grade is 3.01% Pb,4.41% Zn. 1.63 g/t Au, 41.23 g/t Ag. Kyeongju W-Mo-Be Greisen, Stockwork, and Quartz Vein DepositThis deposit (Park amd others, 1969) is hosted in Cretaceous shale and sandstone of the Hadong group and volcanic rock of Yucheon group that are intruded by the Late Cretaceous Bulgugsa biotite granite. The deposit consists mainly of disseminated molybdenite in leucogranite that forms the margin part of agranite stock, and partly in extrusive breccia, and in quartz veins in granite. The deposit is medium size with resources of 260,000 tonnes ore grading 0.2-0.3% Mo. Chilgok Polymetallic Pb-Zn Cu (Ag, Au) Vein and Stockwork DepositThis deposit (Koo and Kim, 1965) is hosted mainly in hornblende granite of the Cretaceous Bulgugsa granite series that south of the intrudes older sedimentary rock of the Sindong Group. The deposit is controlled by joints and faults that mainly strike N40oW and dip 75 to 85o northeast. The fissures are filled by quartz with ore minerals of mainly galena, sphalerite, and pyrite, lesser chalcopyrite and arsenopyrite, and rare pyrrhotite. The deposit is small with resources of 3,000 to possiblly 5,900 tonnes, and reserves of 5,300 tonnes ore.Grades are 0.9-5.5 g/t Au, 154.4-280.8 g/t Ag, 3.9-8.83% Pb and 4.1-7.08% Zn. Wangpiri Sn-W Greisen, Stockwork, and Quartz Vein MineThe deposit (Kim and Shin, 1966) is hosted in Precambrian metasedimentary rock in the Wonnam and Yulri Series and in the Cretaceous Bunchon granite gneiss, granite, and granitic. The deposit is hosted in granitic pegmatite that intrudes the contact between granite and the Yulri Series. The veins are mostly concordant with schistosity in phyllite, mica schist, and micaceous metasandstone, and strike NS to N60oE and dip 30 to 80o northwest. The deposit consists of cassiterite pegmatite veins that are banded structure with alternating quartz and feldspar zones that range from 2 to 22 mm wide. Local homogeneous and coarse granular textures occur. The main ore mineral is cassiterite along with quartz, microcline, perthite, plagioclase, sericite, and muscovite and sparse tourmaline. The deposits consists of small lenses, pipes, or large veins that range from 0.3 to 15 m wide and 5 to 150 m long. Fine cassiterite grains occur occasionally. Cassiterite is generally concentrated in quartz-rich zones in the homogeneous pegmatite vein, and also is disseminated in muscovite-rich zones on the hanging wall in fine grains, and rarely occurs in feldspar-rich zones. Average width of the veins is 1.24 m. The deposit is small with an average grade of 0.45% Sn. Samkwang Polymetaliic Ni Vein DepositThis unusual, multi-stage deposit (Kim, 1982) consists of Ni sulfide minerals in amphibolite bodies that are part of a Precambrian assemblage of granitic gneiss, banded gneiss, and siliceous dikes that are intruded by Cretaceous biotite granite, lamprophyre dikes, quartz veins, and pegmatitic quartz veins. The amphibolite consists of coarse-grained Ni sulfide minerals in fine- to medium-grained ultramafic rock. The deposit occurs in the top parts of amphibolite near the surface and grades downwards into barren or very low-grade parts. The major ore minerals are pyrrhotite with subordinate pentlandite, chalcopyrite, and pyrite that occurs in disseminations, predominantly in the upper ,subsurface part of the amphibolite. Three stages of mineralization occurred: (1) magmatic segregation with formation of disseminated Ni sulfide minerals; (2) deuteric or hydrothermal alteration associated with Cretaceous plutonism with alteration of rock forming minerals; and (3) remobilization of sulfides, mainly pyrrhotite with pentlandite. The ore minerals are pyrrhotite, pentlandite, chalcopyrite, and pyrite, and gangue minerals are plagioclase, sericite, tremolite-actinolite, talc, chlorite, calcite, and quartz. Areas with sulfides are vary from 5 to 8 m thick and 45 to 50 m long. The deposit is small with reserves of 17,820 tonnes ore grading 0.57% Ni. Origin and Tectonic Controls for Gyeongpuk Metallogenic BeltThe belt is interpreted as forming during generation of the Bulgugsa Granite during the Late Cretaceous to Early Tertiary Bulgugsa orogeny. The Bulgugsa Granite consists of biotite granite, granodiorite, porphyry, and felsic and quartz porphyry. The belt is hosted in the Yeongnam Metamorphic Complex, Gyeongsang Supergroup, Yeongnam granulite-paragneiss terrane, that is part of the Sino-Korean Craton, and in the Late Cretaceous Bulgugsa Granite. REFERENCES: Cho and Lee, 1966; Park and others, 1969; Kim and Shin, 1966; Duk Hwan Hwang, this study. |