By Sergey M. Rodionov1, Alexander A. Obolenskiy2

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Yangyang Metallogenic Belt of

Regionally Metamorphosed BIF Deposits

(Belt YG) (South Korea)

This Proterozoic metallogenic belt is hosted in the Proterozoic Gyeonggi Group and Proterozoic Kyeonggi Gneiss Complex (both parts of South China Craton, Gyenggi granulite-paragneiss terrane), and the Jurassic Daebo Granite. The Gyeonggi Group consists mainly of Precambrian metasedimentary rock, including chlorite-sericite-quartz schist and hornblende-biotite-gneiss, and trends north-northeast to south-southwest. The Jurassic Daebo Granite consists of schistose granite, biotite granite, syenite, and felsite porphyry. The major deposit is at Yangyang.

Yangyang Metamorphosed Banded Iron Formation

(BIF, Superior Fe) Deposit

This deposit (Kim and others, 1959) consists of metamorphic magnetite that is hosted in Precambrian biotite gneiss that trends north-northeast to south-southwest, and in syenite intruding the gneiss. The west side of the syenite contains many lenticular-shaped xenoliths of calcsilicate rock, tactite, and amphibolite derived from metasomatized impure limestone. Fe bodies are hosted in the syenite, and are closely associated with tactite or amphibolite. Fe bodies also occur in gneiss, are irregular but generally lenticular, and extend north-south. Three major bodies are at Tapdong, Tomok, and Nonhwa. The ore mineral is mainly magnetite, and gangue minerals are hornblende, epidote, and biotite. Magnetite is commonly massive and compact, but also platy and brittle. The origin of the magnetite deposits is interpreted as a polymetamorphosed BIF deposit that was intruded by syenite. Host limestone was metamorphosed and metasomatized to calc-silicate rock. The deposit is small with an average grade of 55% Fe and reserves of 2,020,280 tonnes ore.

Origin and Tectonic Controls for

Yangyang Metallogenic Belt

The metamorphosed BIF deposits are interpreted as forming during contact metasomatism of BIF and formation of magnetite skarn during intrusion of Jurassic Daebo Granite.

REFERENCES: Kim and others, 1959; Kim and others, 1965; Park, and Hwang, 1995; Duk Hwan Hwang, this study.

MESOPROTEROZOIC

METALLOGENIC BELTS

(1600 to 1000 MA)

Ingili Metallogenic Belt of

Stratiform Zr (Algama type) and

REE (±Ta, Nb, Fe) Carbonatite Deposits

(Belt Ing) (Russia, Far East)

This Mesoproterozoic metallogenic belt occurs at the southern boundary between North Asian Craton and the Verkhoyansk fold and thrust belt. The belt contains a Zr deposit at Algama and several Zr occurrences.

Ingili REE (±Ta, Nb, Fe) Carbonatite Deposit

This deposit (Onikhimovsky and Belomestnykh, 1996) occurs in circular alkaline intrusive body composed of ijolite-melteigite, syenite, and theralite of Precambrian(?) age. Alkaline igneous rock intrudes Archean amphibolite and gneiss, and Neoproterozoic calcareous and clastic rock. Deposit consists of two types of carbonatite - calcite and dolomite. Calcite carbonatite contains Ta-Nb minerals and forms small (up to 150 x 200 m) bodies of irregular shape. Nb and Ta occur in pyrochlore and zircon. Dolomite carbonatite contains REE minerals in veins that are 10 to 80 m long and 0.1-2 to 3 m thick. The deposit is small with an average grade of 1.4% REE oxides; up to 1.1% Nb₂O₅.

Algama Stratiform Zr (Algama Type) Deposit

This deposit (Onikhimovskiy and Belomestnykh, 1996; Buryak and others, 1999) is hosted mainly in subhorizontal dolomite marble that along with other sedimentary rock, form the Neoproterozoic and early Paleozoic sedimentary cover of the Stanovoy block of the North Asian Craton. This deposit consists of hydrozircon and baddeleyite in lenses and veins that occur mainly in a layer of cavernous dolomite marble that ranges up to about 40 m thick. The lenses and veins are subhorizontal, are near surface, and are associated with units containing intensive karsts. The ore occurs mainly as breccia composed of fragments of metamorphic quartz and dolomite cemented by an aggregate of hydrozircon and baddeleyite. Baddeleyite also occurs as loose aggregates formed by weathering of primary ore. Some caverns in the dolomite contain colloform, sinter-type aggregates of hydrozircon and baddeleyite, but breccia ores predominate. The host dolomite is not hydrothermally altered. The deposit is large and has reserves of 73,150 tonnes ZrO₂ with an average grade of 4.62% ZrO₂, and resources of 93,668,900 tonnes ore grading 1.14% WO₃, 0.84% Hf, 0.07% Y, and 0.12% Nb.

Origin and Tectonic Controls for

Ingili Metallogenic Belt

The deposit is interpreted as forming in two stages. Initial chemical-sedimentary deposition of disseminated Zr in shallow marine dolomite. Subsequent concentration during diagenesis, karst formation, and hydrothermal fluids associated with intrusion of rift-related mafic and ultramafic dikes.The deposit formed at hypsometric levels making paleosurface of ground water.

REFERENCES: Buryak and others, 1999.

Tagulskiy Metallogenic Belt of

Muscovite Pegmatite, REE-Li Pegmatite, and

Mafic-Ultramafic-Related Ti-Fe Deposits

(Belt Tag) (Russia, East Sayan)

This Mesoproterozoic(?) metallogenic belt occurs in Tumanshet and Birusa paragneiss terranes of the North Asian Craton. The belt occurs in the Paleoproterozoic Elashsky graben in the northwestern part of East Sayan Mountains, and is 140 km long and 120 km wide (Bryntsev, 1994). The belt along regional of northwest-striking faults (Birjusinsky, Khultsaisky, Belsky, and Kansky faults) and formed during primarily Proterozoic interplate mafic and siliceous magmatism and hydrothermal activity. The metallogenic belt is related to the Mesoproteroterozoic(?) Sayan collisional granitic belt that consists of granite, subalkaline, alkaline granite, and granosyenite plutons and related rocks. Deposits in the belt occur in large districts and consists of: (1) muscovite pegmatite at Gutaro-Birjusinsky; (2) REE pegmatite at Vishnyakovskoye; (3) mafic-ultramafic Fe-Ti at Malo-Tagulskoye. The belt is promising for discovery of new REE and Ti deposits.

Vishnyakovskoye REE-Li pegmatite Deposit

This deposit (Vakhromeev and others, 1983; Makagon and others, 1983; Ryabtsev, 1998) occurs in the Tagul-Tumanshet mobile zone and consists of gently-lying veins in fine-grained ortho-amphibolite, and metamorphosed diabase and gabbro. Pegmatite veins are tabular, upper veins are arched, and range up to 12 m thick and 2 km long. The average grade in explores bodies ranges up to 0.018% Ta₂O₅. The deposit contains both Ta and Li-Ta facies. The Ta facies (with an average grade of 0.026% Ta₂O₅) occurs in the upper, central, and eastern parts of the deposit. The Li-Ta facies (with an average grade 0.014% Ta₂O₅) occurs in deeper layers on the western and southwestern flanks of the deposit. 89% Ta is contained in tantalite, vodginite, microlite, ixiolite, 3.6% in cassiterite, 10.7% as microtraces in rock-forming minerals. Petalite is the primary lithium mineral. Mica and K-feldspar contain Cs and Rb. Pegmatites also contain widespread apatite, beryl, topaz, and fluorite. Pegmatite veins occur in the exocontact zone of the granitoid mass. The deposit is large with an average grade of 0.014-0.026% Ta₂O₅.

Malo-Tagulskoye Mafic-Ultramafic-related Ti-Fe Deposit

This deposit (Mekhonoshin and others, 1986; Starostin 1998) occurs in the Malotagulsky massif of metagabbro in blocks that total 160 km². Fault zones bound occurrences that are about 2 km long and 300-800 m wide. Wall rocks include amphibolite, migmatite, and eclogite. Ore bodies are a series of steeply dipping lenses and layers that extend for 1750 m and are 10-25 m thick. The deposit consists of: (1) disseminations in metagabbro, including magnetite, ilmenite, titanomagnetite, ferri-ilmenite (magneto-ilmenite), hematite with gradational contacts with host rocks; (2) sideronite that consists of silicate minerals with titano-magnetite, ilmenite, and spinel; and (3) thin veinlets and large crossing veins of titano-magnetite and ilmenite which are divided into high-grade (15-24% TiO₂) and medium grade (8-13% TiO₂). The following stages formed the deposit: (1) magmatic with formation of mafic rocks from tholeiitic magma in island arc; (2) progressive metamorphism at granulite facies resulting in initial eclogite, formation of titano-magnetite-ilmenite melts, and formation of oxidized ore minerals in disseminations; and (3) retrograde metamorphism at amphibolite facies and granitization with formation of most ore mineral masses). Age of deposit is interpreted as Mesoproterozoic. The deposit is large and the average grade in disseminated ore is 4.7% TiO₂, and 26.8% Fe.

Origin and Tectonic Controls for

Tagulskiy Metallogenic Belt

The belt is interpreted as forming during widespread mafic and siliceous intraplate magmatism. Belt occurs along northwest-striking regional faults that controlled a Proterozoic magmatic and hydrothermal system.

REFERENCES: Makagon and others, 1983; Vakhromeev and others, 1983; Mekhonoshin and others, 1986; Bryntsev, 1994; Makagon, 2000.

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