U.S. DEPARTMENT OF THE INTERIOR U.S. GEOLOGICAL SURVEY PREPARED IN COLLABORATION WITH: RUSSIAN ACADEMY OF SCIENCES GEOLOGICAL COMMITTEE OF RUSSIA ALASKA DIVISION OF GEOLOGICAL AND GEOPHYSICAL SURVEYS GEOLOGICAL SURVEY OF CANADA SIGNIFICANT METALLIFEROUS AND SELECTED NON-METALLIFEROUS LODE DEPOSITS AND PLACER DISTRICTS FOR THE RUSSIAN FAR EAST, ALASKA, AND THE CANADIAN CORDILLERA By Warren J. Nokleberg (1), Thomas K. Bundtzen (2), Kenneth M. Dawson (3), Roman A. Eremin (4), Nikolai A. Goryachev (4), Richard D. Koch (1), Vladimir V. Ratkin (5), Ilya S. Rozenblum (6), Vladimir I. Shpikerman (4), Yuri F. Frolov (7), Mary E. Gorodinsky (6), Vladimir D. Melnikov (8), Michael F. Diggles (1), Nikolai V. Ognyanov (5), Eugene D. Petrachenko (5), Rimma I. Petrachenko (5), Anany I. Pozdeev (7), Katherina V. Ross (3), Douglas H. Wood (3), Donald Grybeck (9), Alexander I. Khanchuk (5), Lidiya I. Kovbas (5), Ivan Ya. Nekrasov (5), and Anatoly A. Sidorov (4) 1-U.S. Geological Survey, Menlo Park 2-Alaska Division of Geological and Geophysical Surveys, Fairbanks 3-Geological Survey of Canada, Vancouver 4-Russian Academy of Sciences, Magadan 5-Russian Academy of Sciences, Vladivostok 6-Geological Committee of Northeastern Russia, Magadan 7-Geological Committee of Kamchatka, Petropavlovsk- Kamchatsky 8-Geological Committee of Amur Region, Blagoveshchensk 9-U.S. Geological Survey, Anchorage OPEN-FILE REPORT 96-513-B 1997 This report is preliminary and has not been reviewed for conformity with U.S. Geological Survey editorial standards or with the North American Stratigraphic Code. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. INTRODUCTION This report is a written tabular compilation of the significant metalliferous and selected non-metalliferous lode deposits and placer districts of the Russian Far East, Alaska, and the Canadian Cordillera. The report provides detailed summaries of the important features of the significant lode deposits and placer districts along with a summary of mineral deposit models, and a bibliography of cited references. Data are provided herein for 1,079 significant lode deposits and 158 significant placer districts of the region. The tabular data are provided in Table 1 for significant lode deposits, and in Table 2 for significant placer districts at the end of report. Alphabetical indices of the tabular data are provided after Tables 1 and 2. The Alaskan and Canadian mineral deposit data are derived from revisions of Dawson (1984), Nokleberg and others (1987, 1993, 1994a, b), from new unpublished data of the authors, and from recent publications. The Russian Far East mineral deposit data represent new compilations by the Russian authors using cited references and unpublished data of the authors. This report is also published in a paper version (Open-File Report 96-513-A). This report is one of a series of studies on the mineral deposits, metallogenic belts, bedrock geology, and tectonics of the Russian Far East, Alaska, and the Canadian Cordillera. Published major companion studies are: (1) a report on the metallogenesis of mainland Alaska and the Russian Northeast (Nokleberg and others, 1993); and (2) a tectonostratigraphic terrane map of the Circum-North Pacific (Nokleberg and others, 1994c). METALLOGENIC AND TECTONIC DEFINITIONS The following key definitions are provided. Deposit. A general term for any lode or placer mineral occurrence, mineral deposit, prospect, and (or) mine. Metallogenic belt. A geologic unit (area) that either contains or is favorable for a group of coeval and genetically-related, significant lode and placer deposit models. Mine. A site where valuable minerals have been extracted. Mineral deposit. A site where concentrations of potentially valuable minerals for which grade and tonnage estimates have been made. Mineral occurrence. A site of potentially valuable minerals on which no visible exploration has occurred, or for which no grade and tonnage estimates have been made. Overlap assemblage. A postaccretion unit of sedimentary or igneous rocks deposited on, or intruded into, two or more adjacent terranes (Jones and others, 1983; Howell and others, 1985; Nokleberg and others, 1994c). The sedimentary and volcanic parts either depositionally overlie, or are interpreted to have originally depositionally overlain, two or more adjacent terranes, or terranes and the craton margin. Overlapping plutonic rocks, which may be coeval and genetically related to overlap volcanic rocks, link or stitch together adjacent terranes, or a terrane and a craton margin. Prospect. A site of potentially valuable minerals in which excavation has occurred. Significant mineral deposit. A mine, mineral deposit, prospect, or occurrence that is judged as important for the metallogenesis of a geographic region. Terrane. A fault-bounded geologic entity or fragment that is characterized by a distinctive geologic history that differs markedly from that of adjacent terranes (Jones and others, 1983; Howell and others, 1985; Nokleberg and others, 1994c). Constitutes a physical entity, i.e., a stratigraphic succession bounded by faults, inferred faults, or an intensely-deformed structural complex bounded by faults. Some terranes may be displaced (faulted) facies of other terranes. LODE AND PLACER MINERAL DEPOSIT MODELS Classification of Mineral Deposits Metalliferous and selected non-metalliferous lode and placer deposits in this report are classified into various models or types described below. This classification of mineral deposits was derived mainly from the mineral deposit types of Eckstrand (1984), Cox and Singer (1986), Nokleberg and others (1987, 1993, 1994a, b), cited references for specific models, and unpublished data of the Russian authors. The lode deposit types are grouped according to host rock lithologies and (or) origin. Lode deposit types that share a common origin, such as contact metasomatic deposits, or porphyry deposits, are grouped together under a single heading. The mineral deposit types used in this report consist of both descriptive and genetic information that is systematically arranged to describe the essential properties of a class of mineral deposits. Some types are descriptive (empirical), in which instance the various attributes are recognized as essential, even though their relationships are unknown. An example of a descriptive mineral deposit type is the basaltic Cu type in which the empirical datum of a geologic association of Cu sulfides with relatively Cu-rich metabasalt or greenstone is the essential attribute. Other types are genetic (theoretical), in which case the attributes are related through some fundamental concept. An example is the W skarn deposit type in which case the genetic process of contact metasomatism is the essential attribute. For additional information on the methodology of mineral deposit types, the reader is referred to the discussions by Eckstrand (1984) and Cox and Singer (1986). For each deposit type, the principal references are listed in parentheses. Deposits Related to Marine Felsic to Mafic Extrusive Rocks Kuroko Zn-Pb-Cu massive sulfide (Ag, Au, Cd, Sn, Sb, Bi, barite) (D.A. Singer in Cox and Singer, 1986; Franklin, 1993) This deposit type consists of volcanogenic massive to disseminated sulfides that occur in felsic to intermediate marine volcanic, pyroclastic, and bedded sedimentary rocks. The deposit minerals are mainly pyrite, chalcopyrite, sphalerite, and lesser galena, tetrahedrite, tennantite, and magnetite. Local alteration to zeolites, montmorillonite, silica, chlorite, and sericite may occur. The volcanic rocks are mainly rhyolite and dacite flows and tuff with subordinate basalt and andesite. Deposits commonly associated with subvolcanic intrusions that focus heat and provide energy for circulating hydrothermal fluids and leaching reactions. Strata above intrusions display extensive high-temperature alteration, including metal depletion, extreme alkali modification, and silicification. Deposits may be associated with major units of epiclastic breccia and with local growth faults, either rift or caldera-collapse faults. Alteration pipes may develop in portions of faults that immediately underlie the deposits. The depositional environment is mainly hot springs related to marine volcanism in island arcs or in extensional regimes behind island arcs. Besshi Cu-Zn massive sulfide (Cu, Zn, Ag) (D.P. Cox in Cox and Singer, 1986; Slack, 1993) This deposit type consists of thin sheet-like bodies of massive to well-laminated pyrite, pyrrhotite, and chalcopyrite and sphalerite, and lesser sulfide minerals, within thinly laminated clastic sedimentary rocks, basalt, and mafic tuff. Lesser minerals are magnetite, galena, bornite, and tetrahedrite, with gangue quartz, carbonates, albite, white mica, and chlorite. The rock types are mainly marine clastic sedimentary rocks, basaltic and less commonly andesitic tuff and breccia, and local black shale and red chert. Wall rocks may include sericite- and chlorite-rich schist, coticule, tourmalinite, and albite that common form strata-bound lenses or envelopes around the massive sulfide deposit, or may extend as much as five to ten meters into the adjacent host rocks. Coticule, tourmalinite, and albite may occur as stratiform layers that may extend laterally hundreds of meters beyond the massive sulfide deposit. These wall rocks form by hydrothermal alteration and (or) chemical sedimentation coeval with deposition of massive sulfide. Alteration is sometimes difficult to recognize because of metamorphism. Deposits typically form stratiform lenses and sheetlike accumulations of semi-massive to massive sulfide. Footwall feeder zones may occur. The depositional environment is interpreted as submarine hot springs related to the deeper zones of submarine basaltic volcanism along spreading oceanic ridges, possibly in areas where a spreading oceanic ridge occurs near a continental margin that is supplying clastic detritus. Cyprus Cu-Zn-Ag massive sulfide (Au, Pb, Cd, Sn) (D.A. Singer in Cox and Singer, 1986) This deposit type consists of massive sulfides in pillow basalt. The deposit minerals are mainly pyrite, chalcopyrite, sphalerite, and lesser marcasite and pyrrhotite. The sulfides occur in pillow basalt that is associated with tectonized dunite, harzburgite, gabbro, sheeted diabase dikes, and fine-grained sedimentary rocks, all part of an ophiolite assemblage. Beneath the massive sulfides is sometimes stockwork pyrite, pyrrhotite, minor chalcopyrite, and sphalerite. The sulfide minerals are sometimes brecciated and recemented. Alteration in the stringer zone consists of abundant quartz, chalcedony, chlorite, and lesser illite and calcite. Some deposits are overlain by Fe-rich and Mn-poor ochre. The depositional environment consists of submarine hot springs along an axial graben in oceanic or back-arc spreading ridges, or hot springs related to submarine volcanoes in seamounts. Volcanogenic Mn (R.A. Koski in Cox and Singer, 1986) This deposit type consists of sheets and lenses of hausmannite-rhodochrosite, rhodochrosite, and oxidized braunite in intercalated shales, jasper, marine basalt flows, and mafic tuff. The host-volcanic rocks differ from normal tholeiite basalt in being relatively rich in potassium, sodium, and titanium. The deposits generally occur in sequences with abundant chert, rather than in sequences dominated by volcanic rocks. The deposits are often associated with volcanogenic Fe deposits, and sometimes contain complexly-oxidized ferromanganese minerals. The depositional environment is presumably related to hot springs associated with marine basaltic magmatism. No relation exists between zones of Mn-minerals and volcanic edifices. Volcanogenic Fe (Shekhorkina, 1976) This deposit type consists of sheeted magnetite, and rarely magnetite-hematite or magnetite-hydroxide that occur in interlayered dark-gray jasper, shale, sandstone, and sedimentary breccia that contain subordinate subalkaline mafic extrusive rocks,. Associated minerals are pyrite, pyrrhotite, chalcopyrite, arsenopyrite, and other sulfide minerals. Quartz is the dominant gangue mineral, along with Fe-rich chlorite, calcite, and gypsum. The depositional environment is presumably related to hot springs associated with marine mafic volcanism. Deposits Related to Subaerial Extrusive Rocks Au-Ag epithermal vein (D.L. Mosier and others in Cox and Singer, 1986; Sillitoe, 1993a) This deposit type consists of quartz-adularia, and quartz-adularia-carbonate veins with a wide variety of minerals, including Au- and Ag-sulfosalts, pyrite, chalcopyrite, argentite, galena, sphalerite, cinnabar, and stibnite. Associated minerals include electrum, chalcopyrite, Cu- and Ag-sulfosalts, with lesser tellurides, bornite, barite, and fluorite. Alteration minerals include quartz, kaolinite, montmorillonite, illite, and zeolites. One class of epithermal vein deposits, such as those at Creede, Colorado and Dukat, Russian Northeast, has high concentrations of Pb, Zn, and Ag, sometimes high Cu and low Au; another class, such as those at Sado, Japan, has high Au, moderate to low Ag, sometimes high Cu, and generally low Pb and Zn concentrations. For both groups, the host volcanic rock composition ranges from subalkalic andesite to rhyolite. Some deposits are observed or inferred to overlie subvolcanic Cu-Au, Cu-Mo, or Sn magmatic-rock-related deposits. Deposits may be overlain by barren, acid-leached zones, or silicified horizons. The depositional environment is intermediate to felsic volcanic arcs and centers developed over miogeosynclinal rocks (Creede-type) or older volcanic and plutonic rocks (Sado-type). Volcanic-hosted Hg (Plamennoe type) (Kuznetsov, 1974; Babkin, 1975) This deposit type consists of massive to disseminated, veinlet-disseminated and brecciated cinnabar occurring either in: (1) in bed-like, lens-like and irregular bodies mostly in felsic and to a lesser extent, in intermediate and mafic volcanic horizons; or (2) at the contacts of subvolcanic intrusive and volcanic rocks. In addition to cinnabar, the deposit minerals commonly include stibnite, pyrite, and marcasite, with subordinate or rare arsenopyrite, hematite, Pb-, Zn-, and Cu-sulfides, and tetrahedrite, schwatzite, Ag-sulfosalts, gold, realgar, and native mercury. The gangue minerals are mainly quartz, chalcedony, sericite, hydromica, kaolinite, dickite, alunite, carbonate, chlorite, and solid bitumen. Cinnabar and associated minerals commonly occur in multiple layers. Wallrocks may be propylitically altered to quartz, sericite, kaolinite, and epidote. Native mercury is deposited mainly during intense alteration, and, to a lesser extent, by filling of open fissures and voids. This deposit type may be a variety of the epithermal quartz-alunite Au deposit type of Berger (1986). The depositional environment is generally the tectonic boundaries of major volcanic depressions and calderas. Hot spring Hg (J.J. Rytuba in Cox and Singer, 1986) This deposit type consists of cinnabar, antimony, pyrite, and minor marcasite and native mercury in veins and in disseminations in graywacke, shale, andesite and basalt flows, andesite tuff and tuff breccia, and diabase dikes. Various alteration minerals such as kaolinite, alunite, Fe oxides, and native sulfur occur above the paleo-groundwater table; pyrite, zeolites, potassium feldspar, chlorite, and quartz occur below the paleo-groundwater table. The tectonic setting is continental-margin rifting associated with small- volume mafic to intermediate volcanism. The depositional environment is fault and fracture systems near paleo ground- water table in areas of former hot springs. Silica-carbonate Hg (Kuznetsov, 1974; Voevodin and others 1979; J.J. Rytuba in Cox and Singer 1986) This deposit type consists of cinnabar and associated minerals at the contact between serpentinite and graywacke. The Russian equivalent for this deposit type is listwandite. The deposit minerals are mainly common Hg-minerals, including cinnabar, and native mercury, along with stibnite, pyrite, realgar, orpiment, native arsenic, sometimes Ni-and Co-minerals, and sometimes W-minerals, including tungstenite, scheelite, and wolframite. Gangue minerals are mainly dolomite, breunnerite and ankerite in association with quartz, opal, chalcedony, calcite, dickite, and talc. Massive, veinlet, and disseminated minerals commonly occur in irregular lens-like bodies and veins in crush belts and mylonite zones, and in adjacent sedimentary rocks. Cinnabar mineralization is closely associated with silica-carbonate and argillic alteration. The depositional environment consists of zones of normal faults, perhaps superposed on older thrusts, that contain lenses of serpentinite, ultramafic rocks, and graywacke. Volcanic-hosted Sb (Au, Ag, As) vein (Berger, 1978) This deposit type consists of veins, stockwork, and irregular mineralized zones that occur in felsic to intermediate volcanic sequences, intercalated volcaniclastic sedimentary rocks, flows, hypabyssal dikes and sills, and shallow parts of fractured granitic intrusions. The principal deposit mineral is stibnite with accessory arsenopyrite, pyrite, marcasite, berthierite, chalcopyrite, sphalerite, galena, native silver, native gold, native arsenic, cinnabar, realgar, orpiment, jamesonite, tetrahedrite-tennantite, Ag-sulfosalts, carbonate minerals, barite, fluorite, sericite, adularia, and clay minerals. Gangue minerals are mainly chalcedony, quartz and opal. Argillic hydrothermal alteration is common; other alterations may include carbonate minerals, pyrite, and zeolites. Associated volcanic rocks are generally of highly differentiated calc-alkalic composition. Mineralization commonly occurs on the flanks of subaerial volcanoes. Deposit type often occurs at the periphery of volcanic structures that host associated gold-silver, disseminated gold-sulfide, and mercury deposits. The depositional environment is subaerial, calc-alkaline volcanic flows and shallow intrusions. Rhyolite-hosted Sn (B.L Reed and others in Cox and Singer, 1986) This deposit type consists of cassiterite and wood tin that occur in discontinuous veinlets and stockworks, and in disseminations in rhyolite-flow dome complexes. Accessory minerals include topaz, fluorite, bixbyite, pseudobrookite, and beryl. Besides cassiterite and wood tin, the deposit minerals also include hematite, cristobalite, fluorite, tridymite, opal, chalcedony, adularia and zeolites. The associated wall-rock alteration minerals are generally cristobalite, fluorite, smectite, kaolinite and alunite. The host rhyolites commonly contain more than 75 percent silica and are enriched with potassium. Mineralization is controlled by fractured and brecciated zones occurring in the most permeable upper portions of flow-dome complexes. The depositional environment is regions of felsic volcanism erupted onto continental crust. Sulfur-sulfide (S, FeS2 ) (Vlasov, 1976) This deposit type consists of three subtypes: (1) surficial sulfur deposited from gases and solutions; (2) lacustrine deposits formed in volcanic craters; and (3) most valuable economically, replacement deposits formed as metasomatic sheets and as irregular bodies in porous and fractured rocks. All three subtypes are genetically and spatially associated with andesite. The deposit minerals are generally diverse and consist mainly of sulfur and pyrite with lesser variable realgar, orpiment, metacinnabar, stibnite, sphalerite, and molybdenite. Sulfide content increases with the depth grading into massive sulfides. Host rocks are generally hydrothermally altered. Stratiform Deposits in Fine-Grained Clastic and Siliceous Sedimentary Rocks Sedimentary exhalative (SEDEX) Zn-Pb-Ag (J.A. Briskey in Cox and Singer, 1986; Goodfellow and others, 1993) This deposit type consists of stratiform, massive to disseminated sulfides and barite occurring in sheet-like or lens-like tabular bodies that are interbedded with euxinic marine sedimentary rocks including dark shale, siltstone, chert, and sandstone. Many deposits form in half-graben basins, are asymmetrical zoned, and range in form from mound-shaped vent complexes to flanking, interbedded hydrothermal, biogenic, and epiclastic sedimentary accumulations. Generally occur in basinal sediments that cap thick, continental syn-rift sequences of coarse-grained clastic rocks. Sometimes close temporal and in many cases, spatial association with alkaline and tholeiitic basaltic rocks, dikes, and sills that indicate associated hydrothermal activity is related to high-level magmas. The deposit minerals include pyrite, pyrrhotite, sphalerite, galena, and barite, and rare celesite and chalcopyrite. Extensive hydrothermal alteration may occur near vents, including stockwork and disseminated sulfides, silica, albite, and chlorite. The depositional environment consists of marine epicratonal embayments and intracratonic basins with smaller local restricted basins. Bedded barite (G.J. Orris in Cox and Singer, 1986) This deposit type consists of stratiform, massive, and nodular barite interbedded with marine cherty and calcareous sedimentary rocks, mainly dark chert, shale, mudstone, and dolomite. The deposit type is often associated with sedimentary exhalative Zn-Pb or kuroko massive sulfide deposits (both described above). Alteration consists of secondary barite veining and local, weak to moderate sericite replacement. Associated minerals include minor witherite, pyrite, galena, and sphalerite. Also associated are phosphate nodules. The depositional environment consists of epicratonal marine basins or embayments, often with smaller local restricted basins. Stratabound deposits in Coarse Clastic sedimentary Rocks and Subaerial Basalts Sediment-hosted Cu (Kupferschiefer and Redbed) (Bogdanov and others, 1973; Eckstrand, 1984; D.P. Cox in Cox and Singer, 1986) This deposit type consists of disseminated to less prevalent veinlet sulfide ores that occur in lens-like and layered bodies in red clastic sedimentary rocks, including shale, siltstone, and sandstone, that are often intercalated with basalts. The main deposit minerals are bornite, chalcocite, hematite, with rare chalcopyrite as large crystals, metasomatic veinlets, and clastic grains. Wall- rock alteration consists of disappearance of red color of host rocks, and occurrence of quartz-carbonate-sulfide veinlets. The latter are sometimes abundantly associated with low-grade contact or greenschist facies regional metamorphism. Weathering results in development of green sinter and malachite and azurite crusts. The depositional environment is epicontinental, shallow marine basins that occur on passive continental margin shelfs, or adjacent to volcanic island arcs. This deposit type is commonly associated with Cu-bearing, island arc trachybasalts (shoshonites) formed at or near rift zones. Basaltic Cu (Dzhalkan type) (Eckstrand, 1984; Kutyrev, 1984; D.P. Cox in Cox and Singer, 1986) This deposit type consists of stratabound disseminated Cu minerals in basalt lavas erupted into shallow coastal marine basins, and more seldomly onto the subaerial parts of oceanic volcanic islands. The volcanic rocks are generally interbedded with red sandstone, conglomerate and siltstone. The basalts lavas are generally potassic or alkalic and may include shoshonites and trachybasalts. Major deposit minerals are bornite, chalcopyrite, chalcocite, pyrite and native copper. These minerals occur both in the matrix of, and as amygdules in the porous roofs of basalt flows, and in veinlets within the basalts. The wallrocks are altered mainly to epidote, calcite, chlorite and zeolites. The deposit type is often associated with sediment-hosted Cu deposit type (Kupferschiefer and Redbed, described above). The depositional environment is epicontinental, shallow marine basins that occur on passive or rifted continental margin shelfs, or adjacent to oceanic volcanic islands. The depositional environment includes porous roof of basalt flows and synvolcanic fissures. Clastic sediment-hosted Hg (Nikitovka type) (Kuznetsov, 1974; Babkin, 1975) This deposit type consists of cinnabar and associated minerals that occur in lenses, stockworks, and other structures in flysch sequences composed of siltstone, shale, and conglomerate. Ore bodies include stockworks, lenses, bed-like and irregular bodies, and simple and complex veins in fault zones. Mineralization is controlled by sets of fractures, and by feathering major faults in anticlinal structures and dome-like uplifts. The deposit type usually contains several ore horizons. Deposit minerals are mainly cinnabar with subordinate stibnite, realgar, orpiment, various other sulfide minerals and sulfosalts, and native arsenic and native mercury. Gangue minerals are mainly quartz, chalcedony quartz, carbonate minerals, and dickite. Wall rocks may be altered to quartz, argillite, and carbonate minerals. Associated igneous rocks are mainly felsic and intermediate dikes. Mineralization is interpreted to have formed from low-temperature hydrothermal fluids that were related to either deep magmatic chambers or to low- grade regional metamorphism. In many parts of Russia, clastic sediment-hosted Hg deposits commonly occur in rift environments in cratonal areas. However, in the Russian Far East, this model is also applied to Hg deposits that occur in clastic sedimentary rocks that are part of volcanic arc sequences. Sandstone-hosted U (C.E. Turner-Peterson and C.A. Hodges in Cox and Singer, 1986) This deposit type consists of concentrations of uranium oxides and related minerals in localized, reduced environments in medium- to coarse-grained feldspathic or tuffaceous sandstone, arkose, mudstone, and conglomerate. The depositional environment is continental basin margins, fluvial channels, fluvial fans, or stable coastal plain, sometimes with nearby felsic plutons or felsic volcanic rocks. The deposit minerals include pitchblende, coffinite, carnotite, and pyrite. Deposits in Carbonate and Chemical-Sedimentary Rocks Kipushi Cu-Pb-Zn (D.P. Cox and L.R.. Bernstein in Cox and Singer, 1986) This deposit type consists of stratabound, massive sulfides hosted mainly in dolomitic breccia. Generally no rocks of unequivocal igneous origin are related to the deposit. The deposit minerals include pyrite, bornite, chalcocite, chalcopyrite, carrollite, sphalerite, and tennantite with minor reinerite and germanite. Local alteration to dolomite, siderite, and silica may occur. The depositional environment consists mainly of high fluid flow along faults or karst(?)-breccia zones. Southeast Missouri Pb-Zn (J.A. Briskey in Cox and Singer, 1986; Leach and Sangster, 1993) This deposit type consists of stratabound, carbonate- hosted deposits of Pb-, Zn-, and Cu-sulfide minerals in rocks having primary and secondary porosity, commonly related to reefs on paleotopographic highs. This deposit type is also referred to as the Mississippi Valley type. The deposits are hosted mainly in dolomite, but are locally hosted in sandstone, conglomerate, and calcareous shale. The deposit minerals are mainly galena, sphalerite, chalcopyrite, pyrite, and marcasite, with minor siegenite, bornite, tennantite, barite, bravoite, digenite, covellite, arsenopyrite and other associated sulfide minerals. Alteration consists of regional dolomitization, extensive carbonate dissolution, and development of residual shale. The deposit minerals occur at interfaces between gray and tan dolomite, and also in traps at interfaces between permeable and impermeable units. Deposits do not normally display internal mineralogical or chemical zoning. The deposits commonly occur at the margins of clastic basins, generally in undeformed orogenic foreland carbonate platforms. Some occur in carbonate sequences in foreland thrust belts bordering foredeeps. Fewer are associated with rift zones. The depositional environment is areas of shallow-water marine carbonates, with prominent facies control by reefs growing on the flanks of paleotopographic basement highs. Korean Pb-Zn massive sulfide (V.V. Ratkin, this study) This deposit type consists of Pb- and Zn-sulfide minerals in carbonate rocks. The host rocks are mainly limestone, dolomite, and lesser marl. The deposit minerals are mainly pyrite, galena, sphalerite, fluorite, and magnetite. The deposit minerals occur mainly as lenses and beds conformable to bedding in host rocks. Magnetite also forms layers that are interbedded with sulfide minerals, fluorite, and carbonate minerals. Little to no hydrothermal alteration occurs; mainly diagenetic alteration occurs in carbonates and associated rocks. The deposit type is intermediate between the sedimentary exhalative Pb-Zn and Southeast Missouri Pb-Zn deposit types. Examples in the Russian Southeast are the Voznesenskoe and Chernyshevskoe mines. The depositional environment is typically Late Proterozoic to Early Paleozoic carbonate-rich sedimentary rocks in basins that overlap folded metamorphic complexes of the Sino-Korean shield. Ironstone (Superior Fe) (Kosygin and Kulish, 1984; R.A. Eremin and V.I. Shpikerman, this study; W.F. Cannon in Cox and Singer, 1986) Chemical-sedimentary subtype (Kosygin and Kulish, 1984). This subtype consists of sheet-like horizons of magnetite and hematite-magnetite in clastic carbonate rocks that are associated with chert, quartz-sericite-chlorite schist, and dolomite. The deposits occur in early Paleozoic sedimentary rocks formed in basins overlying Precambrian granitic and metamorphic complexes. This subtype is a Paleozoic analog of itabirites. Prikolyma subtype (R.A. Eremin and V.I. Shpikerman, this study). This subtype consists of Fe and Ti minerals that occur in bed-like and lens-like bodies in sandstone grit and conglomerate. The deposit minerals are mainly clastic hematite, magnetite, ilmenite, and zircon grains that form concentrations that range up to 50 to 60 percent of the hosting clastic quartz, and feldspar-quartz sandstone beds. Bedded clastic rocks exhibit parallel-, cross-, and wavy- bedding. Ferruginous sandstones are sometimes interlayered with carbonate rocks, which sometimes form rich iron deposits. Conformable and crossing bodies of massive and brecciated hematite ores also occur in regional metamorphosed carbonate rocks. The deposit type is interpreted as ancient lithified sea beach placers that are often highly metamorphosed and deformed. Stratabound W (Austrian Alps-type) (Denisenko and others, 1986; Rundquist and Denisenko, 1986; V.I. Shpikerman, this study) This deposit type consists of stratabound, thin veinlet, and disseminated scheelite ores that occur in bedded carbonaceous calcareous siltstone and argillite, commonly metamorphosed to phyllite and greenschist. Igneous rocks are generally lacking, except for scarce metamorphosed basalt sills. The deposit minerals are mainly scheelite, pyrite, with lesser realgar, galena and chalcopyrite. The deposit minerals are concentrated in carbonaceous calcareous siltstone beds surrounded by shale or mudstone beds. The deposit minerals may also occur along minor crossing faults, and in associated calcite and quartz veinlets. W is geochemically associated with Sb, Hg, and As. The deposit type is interpreted as forming during metamorphism of carbonaceous sedimentary rocks initially enriched with W. Carbonate-hosted Hg (Khaidarkan type) (Babkin, 1975; Fedorchuk, 1983) This deposit type consists mainly of cinnabar in veinlets and in disseminations that occur in stratabound bodies in dolomite breccia and to a lesser extent in limestone breccia. The host rocks are reef and shelf limestones that formed in carbonate reefs and shelf areas of passive continental margins. The host rocks are subsequently altered to dolomite and brecciated during diagenesis and karst- formation. Mineralization is confined to deep fault zones and is localized under impermeable clay layers. Magmatic rocks are rare diabase sills. The deposit minerals are cinnabar and lesser pyrite, sphalerite, stibnite, and anthraxolite, and rare galena and fluorite. Wall-rock alteration consists of jasperoid, and quartz and calcite veinlets. The depositional environment is artesian thermal water with possible deep sources of Hg. Stratiform Zr (Algama Type) (Zalishchak and others, 1991; Bagdasarov and others, 1990; Nekrasov and Korzhinskaya, 1991) This deposit type 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 ore occurs 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 cavern walls are coated with metamorphic quartz. The host dolomite is not hydrothermally altered. The one large deposit of this type occurs in the northern part of the Khabarovsk province and is hosted mainly in subhorizontal dolomite marble that, along with other miogeoclinal sedimentary rocks, form the Late Proterozoic and Early Paleozoic sedimentary cover of the Stanovoy block of the North Asian Craton. The origin of the deposit is speculative. According B. Zalischak (written commun., 1992) the deposit formed by discharge of hydrothermal solution along a layer of porous dolomite. A sudden pressure fall resulted in a blast. An U-Pb isotopic age of about 100 Ma was obtain for hydrozircon (J.N. Aleinikoff, written commun., 1993). Sedimentary phosphorite (Shkolnik, 1973) This deposit type consists of breccia composed of phosphorite, quartz, dolomite, and calcite that are closely associated with calcareous marine reef complexes. The reef complexes occur in sequences of jasper, shale, siltstone, and mafic volcanic rocks. Phosphorite breccias formed along the reef shelf and consist of fragments of primary phosphorite, limestone, and dolomite, and rarely jasper, volcanic rocks, chert, and shale. Primary phosphorite is rare and occurs as lenses of a coquina composed of inarticulate brachiopods and partly by trilobites that posses with phosphate-bearing shells. The boundaries of deposits are complex and are defined by the occurrence of phosphorite fragments in breccias. The length of the deposits ranges from a few tens of meters to several kilometers; the thickness ranges from 0.5 to 40 meters. The deposits are generally complex and discontinuous. The deposit type occurs mainly in the Galam terrane in the Russian Southeast and is associated with volcanogenic Mn and Fe deposits. The principal phosphorite deposits in the Galam terrane are the North-Shantary, Ir-Nimiiskoe, Nelkanskoe, and Lagapskoe deposits. Deposits Related to Calc-Alkaline and Alkaline Granitic Intrusions- Veins and Replacements Polymetallic veins (D.P. Cox in Cox and Singer, 1986; N.A. Goryachev, this study) This deposit type consists of quartz-carbonate veins often with Ag-bearing minerals, gold, and associated base- metal sulfides. The veins are related to hypabyssal intrusions in sedimentary and metamorphic terranes, or to metamorphic fluids forming during waning regional metamorphism. The associated intrusions range in composition from calcalkaline to alkaline and occur in dike swarms, hypabyssal intrusions, small to moderate size intermediate to granitic plutons, locally associated with andesite to rhyolite flows. The deposit minerals include pyrite, and sphalerite, sometimes with chalcopyrite, galena, arsenopyrite, tetrahedrite, Ag sulfosalts, native gold, electrum, and argentite. Alteration consists of wide propylitic zones, and narrow sericite and argillite zones. The depositional environment is near-surface fractures and breccias within thermal aureoles of small to moderate-size intrusions, including within the intrusions. In the Russian Northeast, polymetallic veins are divided into: (1) Au-polymetallic veins that contain gold and Pb-Zn- Cu sulfide minerals and arsenopyrite; (2) polymetallic veins with varying amounts of cassiterite and (or) stannite with abundant Fe, Pb, Zn, and Cu sulfide minerals; and (3) Ag- polymetallic veins enriched with galena, and Ag and Pb sulfosalts. In this region, polymetallic veins occur: (1) mainly in flysch or olistostromes in Mesozoic accretionary wedges; or (2) sometimes in postaccretionary volcanic rocks. Polymetallic veins are analogs of skarn deposits and occur where noncalcareous clastic rocks dominate instead of carbonate rocks. Sb-Au veins (simple Sb deposits) (J.D. Bliss and G.A. Orris in Cox and Singer, 1986; Nokleberg and others, 1987) This deposit type consists of massive to disseminated stibnite and lesser gold in quartz-carbonate veins, pods, and stockworks that occur in or adjacent to brecciated or sheared fault zones, in sedimentary, volcanic and metamorphic rocks, adjacent to granitic plutons, in contact aureoles around granitic plutons, and peripheries of granodiorite, granite, and monzonite plutons. Some Sb-Au vein deposits grade into polymetallic vein deposits. Associated minerals are mainly arsenopyrite, chalcopyrite, and tetrahedrite, and sometimes cinnabar, galena, and sulfosalts. Alteration minerals are mainly quartz, sericite, and clay minerals. Associated granitic plutons are often strongly peraluminous. The depositional environment is faults and shear zones, epizonal fractures adjacent to or within the margins of epizonal granitic plutons. Sn quartz veins (Rudny Gory or Replacement Sn) (Kosygin and Kulish, 1984; W.D. Sinclair and R.V. Kirkham in Eckstrand, 1984; B.L. Reed in Cox and Singer, 1986; Lugov, 1986) This deposit type consists of simple and complex infilling and replacement veins, vein systems, and stockworks that occur in the apices of collisional mesozonal and hypabyssal granitoid plutons, and above granitic domes. The host rocks are commonly metamorphosed shale, sandstone, and sometimes carbonate rocks. This deposit type is commonly associated with multiple intrusions of biotite, two-mica, alkalic, alaskite granites. Granite, pegmatite and aplite dikes are common. Volatiles are dominated by fluorine, and boron content of granites is low. The deposits tend to occur within or above the apices of granitic cusps and ridges. The deposit minerals are cassiterite, wolframite, albite, muscovite, topaz, fluorite, arsenopyrite and lšllingite. Less common are potassium feldspar, tourmaline, beryl, scheelite, molybdenite, Ta-Ni-minerals, Bi-minerals, pyrrhotite, sphalerite, galena, and chalcopyrite. Complex Sn-W ores are dominate. Quartz is the dominant gangue mineral. The dominant wall rock alteration is formation of greisen. The deposit type is associated with Sn-greisen and Sn-skarn, wolframite-quartz veins, and U and F deposits. Sn silicate-sulfide veins (Cornish type) (Kosygin and Kulish, 1984; W.D. Sinclair and R.V. Kirkham in Eckstrand, 1984; Lugov, 1986; B.L. Reed in Cox and Singer, 1986) This deposit type consists of fissure veins, mineralized zones, stockworks, and pipe-like bodies related to multiple granitoid plutons, and to isolated small intrusions of gabbro-diorite, quartz diorite, and potassic alaskite granites. Late-stage tourmaline-bearing granites and pegmatites also occur. The deposit type commonly occurs in late orogenic to post-orogenic settings. Sn mineralization is commonly fault-controlled, and occurs near and above intrusive rocks. The deposit minerals are mainly tourmaline, chlorite, and quartz, with lesser cassiterite, pyrrhotite, pyrite, chalcopyrite, galena, sphalerite, arsenopyrite, wolframite, scheelite, bismuthinite, axinite, fluorite, muscovite, sericite, stannite, sulfostannates, Pb-, Sb-, Cu- and Ag-sulfosalts, gold, silver, stibnite, calcite, and clay minerals. Alteration minerals are tourmaline, muscovite, quartz, and chlorite. The deposit type includes tourmaline and chlorite subtypes. The upper and lower portions of ore vein systems are dominated by sulfides, and silicates and quartz, respectively. Sn polymetallic veins (Southern Bolivian type) (Lugov, 1986; Yukio Togashi in Cox and Singer, 1986) This deposit type consists of cassiterite and associated minerals in veins, stockworks, mineralized zones and breccia pipes. The deposits are controlled by sets of regional faults and fractures in subvolcanic and volcanic structures. Associated igneous rocks are hypabyssal and subvolcanic diorite, granodiorite, and hypabyssal-andesite intrusions, and felsic, intermediate, and mafic dikes. The deposit minerals are cassiterite, pyrrhotite, pyrite, stannite, sphalerite, galena, chalcopyrite, wolframite, tetrahedrite, tennantite, Bi-minerals, sulfostannates, arsenopyrite, Pb-, Au-, and Sb- sulfosalts, with subordinate quartz, Mn-Fe carbonate minerals, sericite, and kaolinite. Tourmaline and chlorite may also occur. This deposit type may also include Sn-Ag deposits containing freibergite, pyrargyrite, polybasite, andorite, stephanite, argentite, argyrodite, canfieldite and others. The principal wall-rock alterations are sericite, chlorite, quartz, kaolinite, and alunite. The deposit type is associated with Sn-silicate-sulfide and Ag polymetallic vein, rhyolite-hosted Sn, porphyry Sn, and Au- Ag epithermal vein deposits. The depositional environment is fissures in and around felsic, continental marginal volcanic arcs. Mineralization occurs in volcanic rocks above intrusions, but may be far-removed from granitic rocks. Co-arsenide polymetallic veins (Borisenko and others, 1984; (R.A. Eremin and V.I. Shpikerman, this study) This deposit type consists of quartz-tourmaline and quartz-chlorite veins containing Co, As, Bi, and Ag and Au minerals. The veins are associated with hypabyssal intrusions varying from diorite to granite, and widespread albitized granite-porphyry dikes. Mineralization occurs in: (1) fractures and in brecciated zones in siltstone, shale, and sandstone; (2) contact metamorphic aureoles around intrusions or, more seldom, in intrusions; and (3) sometimes greisen and skarn. The deposits are often confined to cross- faults. The deposit minerals are arsenopyrite, pyrite, pyrrhotite, lšllingite, cobaltite, skutterudite, smaltite, glaucodot, chloantite, bismuthinite, and Au-, Ag-, Pb-, and Bi-tellurides and selenides. Vein gangue minerals are quartz, chlorite, tourmaline, calcite, fluorite, and adularia. Carbonatite-related Ta, Nb, REE stockwork and vein (Smirnov, 1982; Dawson and Curie, 1984) This deposit type consists of stockworks, metasomatic veins, and lenses with various Ta-Nb and REE minerals. The ore minerals include pyrochlore, betafite, bastnasite, parisite, monazite, columbite, chevkinite, yttrialite, melanocerite, yttrotitanite, hydrothorite, and zircon. Ore mineralization is often associated with alkaline metasomatic rocks (fenite) that alter alkaline granite and syenite. The stockworks, vein, and lenses are associated with alkaline igneous complexes that presumably include carbonatite at depth. The igneous complexes include large zoned batholiths, zoned stocks, alkalic dikes series, and carbonate veins. The zoned batholiths and stocks generally contain two or more of the following lithologies: pyroxenite, gabbro, urtites, ijolite, foyaite, nephelinite, alkaline syenite, granite, and various carbonatites. Zonation commonly consists of carbonatites in the center, medial zones of ultramafic rocks, and peripheral zones of ijolite and nepheline syenite. Locally the zonation sequence may be reversed or more complex. The carbonatites generally consist of various assemblages of augite-diopside-calcite, forsterite-calcite, aegirine-dolomite, aegirine-ankerite, calcite, ankerite, and other minerals. This type of deposit is interpreted as having formed during craton rifting, or within terranes that formed by rifting of cratons. Deposits Related to Calc-Alkaline and Alkaline Granitic Intrusions - Skarns and Greisens Cu (±Fe, Au, Ag, Mo) skarn (contact metasomatic) (D.P. Cox and T.G. Theodore in Cox and Singer, 1986) This deposit type consists of chalcopyrite, magnetite, and pyrrhotite in calc-silicate skarns that replace carbonate rocks along intrusive contacts with plutons ranging in composition from quartz diorite to granite, and from diorite to syenite. Zn-Pb-rich skarns tend to occur farther from the intrusion; Cu- and Au-rich skarns tend to occur closer to the intrusion. Associated minerals are pyrite, hematite, galena, molybdenite, sphalerite, and scheelite. Mineralization is multistage, with several stages of mineral deposition. The deposit type is commonly associated with porphyry Cu-Mo deposits. The depositional environment is mainly calcareous sedimentary sequences intruded by felsic to intermediate granitic plutons. Zn-Pb (±Ag, Cu, W) skarn (contact metasomatic) and associated Manto replacement deposits (D.P. Cox in Cox and Singer, 1986) This deposit type consists of sphalerite and galena in calc-silicate skarns that replace carbonate rocks along intrusive contacts with plutons varying in composition from quartz diorite to granite, and from diorite to syenite. Zn- Pb-rich skarns tend to occur farther from the intrusion relative to Cu- and Au-rich skarns. Associated minerals are pyrite, chalcopyrite, hematite, magnetite, bornite, arsenopyrite, and pyrrhotite. Metasomatic replacements consist of a wide variety of calc-silicate and related minerals. In the Russian Far East, the deposit type generally occurs at a considerable distance from source granitic intrusions, at the contacts of limestones with siltstones and felsic volcanic rocks. Ore bodies are rather narrow, but may extend down dip to 1 km. The deposits are controlled by ring faults around volcanic-tectonic depressions. The depositional environment is mainly calcareous sedimentary sequences intruded by felsic to intermediate granitic plutons. Au, Co, and As skarn (Nekrasov and Gamyanin, 1962; Bakharev and others, 1988; N.A. Goryachev, this study) This deposit type forms along the contacts between siltstone and marble beds during contact metamorphism near intrusions of granodiorite and granite. The skarn is typically composed of pyroxene, grossularite-andradite garnet, and lesser axinite and scapolite. The ore bodies consist of small masses of sulfoarsenides and arsenides along with gersdorffite, arsenopyrite, lollingite, and cobaltite. Native gold occurs in association with bismuth and Te-minerals, including native bismuth, joseites, hedlyite, and bismuthine. Gold grade ranges up to 20 g/t; size is usually less than 0.1 mm, and fineness ranges from 640 to 999. W skarn and greisen (adapted from D.P. Cox in Cox and Singer, 1986) This deposit type consists of scheelite in calc-silicate skarns that replace carbonate rocks along or near intrusive contacts of quartz diorite to granite plutons. Associated minerals are molybdenite, pyrrhotite, sphalerite, chalcopyrite, bornite, pyrite, and magnetite. Metasomatic replacements consist of a wide variety of calc-silicate and related minerals. In the Russian Far East, scheelite typically occurs in quartz-topaz and quartz-mica greisen that formed during replacement of older skarns. The depositional environment is along contacts and in roof pendants in batholiths, and in contact metamorphic aureoles of stocks that intrude carbonate rocks. Fe (±Au, Cu, W, Sn) skarn (D.P. Cox in Cox and Singer, 1986) This deposit type consists of magnetite and (or) Fe sulfides in calc-silicate skarn that replace carbonate rocks or calcareous clastic rocks along intrusive contacts with diorite, granodiorite, granite, and coeval volcanic rocks. The chief associated mineral is chalcopyrite. Metasomatic replacements consist of a wide variety of calc-silicate and related minerals. The depositional environment is calcareous sedimentary sequences intruded by granitic or siliceous volcanic stocks. Sn greisen and skarn (B.L. Reed in Cox and Singer, 1986) These two deposit types commonly occur in the same area, and may grade into one another. The Sn greisen deposit type consists of disseminated cassiterite, cassiterite-bearing veinlets, and Sn sulfosalts in stockworks, lenses, pipes, and breccia in granite altered to greisen, mainly biotite and (or) muscovite leucogranite emplaced in a mesozonal to deep volcanic environment. Sn greisens are generally postmagmatic and are associated with late-stage, fractionated granitic magmas. Associated minerals include molybdenite, arsenopyrite, beryl, scheelite, and wolframite. Alteration minerals consist of incipient to massive replacement by quartz, muscovite, tourmaline, and fluorite. The Sn skarn deposit type consists of Sn, W, and Be minerals in skarns, veins, stockworks, and greisen near intrusive contacts between generally epizonal(?) granitic plutons and limestone. The deposit minerals include cassiterite, sometimes with scheelite, sphalerite, chalcopyrite, pyrrhotite, magnetite, and fluorite. Alteration consists of greisen near granite margins, and metasomatic andradite, idocrase, amphibole, chlorite, chrysoberyl, and mica in skarn. Sn-B (Fe) Skarn (Ludwigtite type) (Lisitsin, 1984; V.I. Shpikerman, this study) This deposit consists of metasomatic replacement of dolomite by mainly ludwigite and magnetite adjacent to granitic plutons thereby forming Sn-B (Fe) magnesium skarn deposits. Ludwigite forms up to 70 to 80 percent of some ore bodies, and Sn occurs as an isomorphic admixture in ludwigite. Other minerals in the magnesian skarns include magnetite, suanit (Mg2B5O), ascharite, kotoite, datolite, harkerite, monticellite, fluroborite, clinohumite, calcite, periclase, forsterite, diopside, vesuvianite, brucite, garnet, axinite, phlogopite, serpentine, spinel, and talc. Interlayered limestone is metasomatically replaced by pyroxene-garnet-calcite skarn that is commonly altered to greisen thereby forming Sn skarn composed of cassiterite, scheelite, pyrrhotite, arsenopyrite, sphalerite, chalcopyrite, and lšllingite. The magnesium and associated calcic skarn ore bodies generally form near highly irregular (convoluted) contacts of granite plutons, and in large xenoliths of carbonate rocks. Most granitic rocks associated with these deposits are interpreted as having formed in collision environments. Boron skarn (datolite type) (Nosenko and others, 1990; Ratkin, and others, 1992; Ratkin and Watson, 1993) This deposit type consists of a boron skarn composed of danburite and datolite that is associated with garnet- hedenbergite-wollastonite skarn. The boron-bearing skarn is interpreted as having formed during successive metasomatic replacement of limestone with silicates (wollastonite, grossularite-andradite, and hedenbergite) and subsequently by borosilicates (danburite, datolite, and axinite), quartz, and calcite. The deposit is characterized by thin-banded wollastonite that forms kidney-shaped aggregates of pyroxene and datolite that formed the walls of paleohydrothermal cavities in limestone. The hydrothermal cavities occur to depths of up to 500 m from the paleosurface, above a zone of a metasomatic wollastonite and grossularite. The central part of these cavities (0.5 to 50.0 m across) was filled with danburite druses. Danburite was decomposed after the second (boron) metasomatic event, and remobilized boron was redeposited at higher paleogypsometric levels as datolite associated with garnet-hedenbergite skarn. The origin of neighboring Pb-Zn deposits is related to these late skarns. Boron isotopic data indicate the source for boron solutions was a deep-seated granitoid intrusion. The formation of early grossular-wollastonite skarns, thin-banded wollastonite aggregates with datolite, and danburite accumulations occurred, by geological data, at depths, simultaneous to the formation of postaccretion ignimbrite sequence, overlying the accretionary wedge. The geologic setting for the deposit is large tectonic lens of limestone, with lateral dimensions of 0.5 by 2.0 km, in an accretionary wedge containing a highly-deformed matrix of siltstone and sandstone matrix. The accretionary wedge is overlain by felsic volcanic rocks. The one example of this deposit is the large Dalnegorsk B mine in the Russia Southeast that constitutes the main source of boron in Russia. Fluorite greisen (Govorov, 1977) The deposit type consists of fine-grained, dark-violet rock composed of fluorite (63 to 66%) and micaceous minerals, mainly muscovite (25 to 35%), along with lesser ephesite and phlogopite. Subordinate minerals are (in decreasing order) tourmaline, sellaite, cassiterite, topaz, sulfides, and quartz. The ore bodies occur as veins and concordant to limestone layers as lenticular and flame-shape bodies, consist of apocarbonate greisens. The deposit type occur in limestone intruded by lithium-fluorine S-type granites. Metasomatic rocks, replacing limestone, occur at and above the contact with granitic intrusions. Pegmatoid- type muscovite-quartz veins with molybdenite-cassiterite- salite, vesuvianite-salite-andradite, and scapolite skarn also occur near intrusive contacts and are interpreted as having formed prior the formation of fluorite-mica greisen. Geologic setting is thick clastic limestone sequences that formed along an active continental margin. Boron isotopic composition of tourmaline indicate a primary evaporite source (V. Ratkin, written commun., 1994) suggesting that deep-seated evaporites in the zone of granitic magma generation were the source of fluorine. Scarce quartz and the absence of paragenetic calcite suggest an extremely high activity of fluorine in silica-poor solutions. The deposit closest to this type in Alaska is at Lost River. The largest deposit of this type in the southern Far East Russia is at Voznesenka that constitutes the largest known Russian fluorspar deposit. Deposits Related to Calc-Alkaline and Alkaline Granitic Intrusions-Porphyry and Granitic Plutons-Hosted Deposits Porphyry Cu-Mo (Au, Ag) (D.P. Cox in Cox and Singer, 1986; Titley, 1993) This deposit type consists of stockwork veinlets and veins of quartz, chalcopyrite, and molybdenite in or near porphyritic intermediate to felsic intrusions. The veinlets and veins contain mainly quartz and carbonate minerals. The intrusions occur mainly in stocks and breccia pipes that intrude granitic, volcanic, or sedimentary rocks. Associated minerals are pyrite and peripheral sphalerite, galena, and gold. Alteration minerals consist of quartz, K-feldspar, and biotite or chlorite. Most deposits exhibit varying amounts of hypogene alteration, including sodic, potassic, and phyllic alteration. Alteration is systematic, but variable between districts. Supergene alteration is a key factor in the initial discovery of deposits. The host igneous rocks are felsic and calc-alkalic. Widespread, episodic development of abundant joints in intrusions and wall rocks. The depositional environment is high-level intrusive porphyries that are contemporaneous with abundant dikes, faults, and breccia pipes that formed in the evolution of andesite stratovolcanoes. The tectonic environment is mainly weakly to strongly alkalic granitic plutons emplaced in back-arc settings of subduction zones. Porphyry Mo (±W, Sn, Bi) (T.G. Theodore in Cox and Singer, 1986; Carten and others, 1993) The porphyry Mo deposit type consists of quartz- molybdenite stockwork veinlets in granitic porphyries and adjacent country rock. The porphyries range in composition from tonalite to granodiorite to monzogranite. Associated minerals are pyrite, scheelite, chalcopyrite, and tetrahedrite. Alteration consists of potassic grading outward to propylitic, sometimes with phyllic and argillic overprints. Deposit type divided into two associations: (1) high-grade, rift-related deposits with fluorine-rich, highly evolved rhyolitic stocks that belong to a high-silica rhyolite-alkalic suite; and (2) low-grade, arc-related deposits accompanied by fluorine-poor, calc-alkalic stocks or plutons that belong to a differentiated monzogranite suite. The high-grade, fluorine-rich deposits are also associated with intraplate alkaline igneous rocks. The depositional environment for porphyry Mo deposits is epizonal levels of a thick continental crust. Porphyry Sn (B.L. Reed in Cox and Singer, 1986; Evstrakhin, 1988; Menzie and others, 1992; R.A. Eremin, this study) This deposit type consists of mainly cassiterite and associated minerals in stockworks, veinlets, and disseminations that occur in veins, pipes, and shoots. The deposit minerals are cassiterite, quartz, pyrrhotite, pyrite, arsenopyrite, chalcopyrite, sphalerite, galena, stannite, wolframite, muscovite, chlorite, tourmaline, albite, adularia, siderite, rhodochrosite, calcite, topaz, fluorite, sulfostannates, and Ag and Bi minerals. Mineralization occurs in shallow complex multiphase granitic plutons, granitic porphyry stocks, subvolcanic and volcanic rhyolite breccias, and also in coeval volcanic rocks and surrounding clastic rocks. Associated features are magmatic- hydrothermal breccias, and extensive metasomatic propylitic alteration along with formation of quartz, tourmaline, sulfide minerals, and sericite. Some deposits exhibit a quartz-tourmaline core with a peripheral zone of sericite. The deposit type is often associated with Sn- and Ag-bearing polymetallic veins. Other features of this deposit type are complex ore composition, variable mineral composition, extensive development of stockworks, extensive metasomatic alteration, both veinlet and disseminated. The depositional environment is mainly volcanic-plutonic igneous arcs formed on continental crust. For simplicity, this deposit type also includes Sn deposits that occur in granitic plutonic rocks. This type of granitoid-hosted Sn deposit may eventually be defined as a new mineral deposit type. Granitoid-related Au (R.I. Thorpe and J.M. Franklin, in Eckstrand, 1984; Sidorov and Rozenblum, 1989; Aksenova, 1990; Gamyanin and Goryachev, 1990, 1991; Sillitoe, 1993b; N.A. Goryachev, this study) This deposit type consists of two subtypes: (1) porphyry Au; and (2) Au-REE quartz vein. The porphyry Au subtype consists of fissure veins, en-echelon vein systems, and veinlet-stockwork zones with disseminated gold and sulfide minerals that occur generally in complex small granitic intrusions in volcanic-plutonic complexes. The deposit minerals are native gold, Au-bearing tellurides and sulfide minerals, with accessory quartz, tourmaline, muscovite, sericite, chlorite, feldspar, carbonate minerals, and fluorite. Disseminated sulfide minerals in wall rocks, especially arsenopyrite, are commonly enriched in Au and Ag. Alteration to greisen is common with formation of quartz, sericite, tourmaline, chlorite. Plutonic rock composition includes gabbro, diorite, granodiorite, and granite of both calc-alkalic and sub-alkalic compositions. The deposits are associated with composite porphyry stocks of steep, cylindrical form that commonly intrude coeval volcanic piles. Stocks and associated volcanic rocks range in composition from low-potassium calc-alkalic through high- potassium calc-alkalic to potassic alkalic. The deposits may occur as disseminations within granitic plutons, at apices of plutons, or in contact metamorphic aureoles. The deposit type displays systematic mineralogy and chemical environment; and is often associated with polymetallic vein deposits with disseminated Au-bearing sulfide minerals, Au- bearing epithermal vein, and porphyry deposits. Advanced argillic alteration is widespread in shallow parts of deposit. Underlying sericitic alteration is typically minor. In Alaska and the Canadian Cordillera, the depositional environment is tentatively interpreted as subduction- related, epizonal plutons intruded into miogeoclinal sedimentary rocks that in some cases were regionally metamorphosed and deformed before intrusion. The Au-REE quartz vein subtype, common in the Russian Northeast, consists of quartz veins and stockworks that occur in the apical portions of small granodiorite and granite plutons, and rarely in contact metamorphosed rocks above the plutons. The quartz veins and stockworks are dominated by quartz along with muscovite, tourmaline, and K- feldspar. The main deposit minerals are gold, arsenopyrite and Co-arsenopyrite, lollingite, wolframite, scheelite, pyrrhotite, and niccolite. Native gold is associated with bismuth and Bi-Te-minerals. Au-Ag telluride minerals are scarce. The host rocks exhibit incipient alteration to greisen with occurrence of quartz, white mica, carbonate minerals, and chlorite. The quartz veins and stockworks are often associated with post-contact metamorphic Au-quartz and Sn-W-quartz veins. Felsic plutonic U-REE (Nokleberg and others, 1987) This deposit type consists of disseminated uranium minerals, thorium minerals, and REE-minerals in fissure veins and alkalic granite dikes in or along the margins of alkalic and peralkalic granitic plutons, or in granitic plutons, including granite, alkalic granite, granodiorite, syenite, and monzonite. The deposit minerals include allanite, thorite, uraninite, bastnaesite, monazite, uranothorianite, and xenotime, sometimes with galena and fluorite. The depositional environment is mainly the margins of epizonal to mesozonal granitic plutons. W veins (Kosygin and Kulish, 1984; D.P. Cox and W.C. Bagby in Cox and Singer, 1986) This deposit type consists mainly of massive and disseminated wolframite and molybdenite in quartz veins. Other deposit minerals are bismuthinite, pyrite, pyrrhotite, arsenopyrite, bornite, chalcopyrite, scheelite, cassiterite, beryl, and fluorite. The veins occur in the upper level, apices of granitic plutons, including alaskite, and in peripheral, contact metamorphosed sandstone and shale. Associated hydrothermal alteration includes formation of greisen, albite, chlorite, and tourmaline. The depositional environment is tensional fractures in epizonal granitoid plutons that intruded, and in some cases formed from anatectic melting of continental crust. The deposit type is sometimes associated with Sn-W vein, Mo-W vein, and Sn greisen deposits. Deposits Related to Mafic and Ultramafic Rocks Zoned mafic-ultramafic Cr-PGE (±Cu, Ni, Au, Co, Ti, or Fe) (Alaskan PGE) (N.J Page and Floyd Gray in Cox and Singer, 1986) This deposit type consists of crosscutting ultramafic to mafic plutons with approximately concentric zoning that contain chromite, native PGE, PGE minerals and alloys, and Ti-V magnetite. The deposit minerals include combinations of chromite, PGE minerals and alloys, pentlandite, pyrrhotite, Ti-V magnetite, bornite, and chalcopyrite. In most areas of Alaska, the depositional environment consists of intermediate-level intrusion of mafic and (or) ultramafic plutons that are interpreted as the deeper-level magmatic roots to island-arc volcanoes. Zoned ultramafic, mafic, felsic, and alkalic PGE-Cr and apatite-Ti (Marakushev and others, 1990) This deposit type consists of veinlets, disseminations, and zones of hydrothermal metasomatic alteration in dunites associated with ultramafic to mafic alkalic-potassic intrusions. PGE minerals are associated with, and are intergrown with chromite and olivine. In metasomatic zones, where chromium pyroxene occurs, PGE minerals are intergrown with magnetite, pyroxene, and phlogopite. The major PGE mineral is ferroplatinum with inclusions of iridosmine. Accessory sulfide and arsenide minerals also occur, including cooperite, sperrylite, hollingworthite, konderite, inaglyite, laurite-euclimanite, and others. In associated pyroxene-hornblende gabbro and pyroxenites intrusions, apatite-Ti minerals may also occur, including disseminated apatite, titanomagnetite, ilmenite, and local PGE minerals. Weathered pyroxenites could be a raw material for vermiculite. The depositional environment is the intermediate-level intrusion of mafic and (or) ultramafic plutons that are interpreted as the magmatic roots to island-arc volcanoes. Anorthosite apatite-Ti-Fe (Kosygin and Kulish, 1984; Force in Cox and Singer, 1986) This deposit type occurs in anorthosite plutons composed of andesine and andesine-labradorite. The anorthosite plutons are highly-alkalic and are associated with gabbro, ferrodiorite, syenite, alkalic granite, and sometimes mangerite that intrude granulite-facies country rocks. The principal deposit minerals are apatite, titanomagnetite, and ilmenite that occur either as: (1) disseminations near melanocratic gabbro, pyroxenites, and dunites along the margins of the anorthosite plutons; or (2) rich apatite (nelsonite) veins that occur in tectonically weak zones. Associated minerals are lesser ilmenite and magnetite. The depositional environment is intrusion into the lower crust under hot, dry conditions. Gabbroic Ni-Cu (synorogenic-synvolcanic; irregular gabbro pipes and stocks) (N.J Page in Cox and Singer, 1986) This deposit type consists of massive lenses, matrix, and disseminated sulfides in small to medium-size composite mafic and ultramafic intrusions in metamorphic belts of metasedimentary and metavolcanic rocks. The deposit minerals include pyrrhotite, pentlandite, and chalcopyrite, sometimes with pyrite, Ti- or Cr-magnetite, and PGE minerals and alloys. Accessory Co-minerals also occur in some deposits. In most areas of Alaska, the depositional environment consists of post-metamorphic and post-deformational, intermediate-level intrusion of norite, gabbro-norite, and ultramafic rocks. Podiform Cr (J.P. Albers in Cox and Singer, 1986) This deposit type consists of podlike masses of chromite in the ultramafic parts of ophiolite complexes, locally intensely faulted and dismembered. The host rock types are mainly dunite and harzburgite, commonly serpentinized. The depositional environment consists of magmatic cumulates in elongate magma pockets. Associated minerals are magnetite and PGE-minerals and alloys. Hornblende-Peridotite Cu-Ni (Shcheka and Chubarov, 1987) This deposit type consists of pentlandite, Zn-bearing chrome spinel, pyrrhotite, chalcopyrite, and bornite that occur in veinlets and as disseminations in hornblendite- peridotite-norite-diorite intrusions. A paragenetic sequence of magmatic amphibole, olivine commonly garnet indicate formation at great depth. The host intrusions are characterized by graphite and native iron, and subordinate aluminum and magnesium-free chromite that indicate reducing crystallization conditions. Examples are the Kvinum, Shanuch, and Kuvalorog deposits in the southern Kamchatka Peninsula. Serpentine-hosted asbestos (N.J Page in Cox and Singer, 1986) This deposit type consists of chrysotile asbestos developed in stockworks in serpentinized ultramafic rocks. The depositional environment is usually an ophiolite sequence, sometimes with later deformation of igneous intrusion. Associated minerals are magnetite, brucite, talc, and tremolite. Deposits Related to Regionally Metamorphosed Rocks Au quartz veins (includes concordant vein, and shear zone Au) (B.R. Berger in Cox and Singer, 1986) This deposit type includes low-sulfide Au quartz vein, turbidite-hosted, concordant vein, and shear zone Au deposits types and consists of gold in massive, persistent quartz veins in regionally metamorphosed volcanic rocks, metamorphosed graywacke, chert, and shale. The veins are generally late synmetamorphic to postmetamorphic and locally cut granitic rocks. Associated minerals are minor pyrite, galena, sphalerite, chalcopyrite, arsenopyrite, and pyrrhotite. Alteration minerals include quartz, siderite, albite, and carbonate minerals. The depositional environment is low-grade metamorphic belts. Disseminated Au-sulfide (Maiskoe type) (Sidorov, 1987) This deposit type consists of fine-grained, disseminated sulfide minerals with subordinate veinlets and veins that occur in deformed and metamorphosed clastic metasedimentary rocks, mainly black shale. Gold occurs mainly in finely- dispersed sulfide minerals, mainly in acicular arsenopyrite, and Au-rich pyrite. Other deposit minerals are subordinate pyrrhotite, sphalerite, galena, chalcopyrite, various sulfosalts, quartz, and stibnite. Quartz-stibnite is the latest-formed assemblage. The deposits occur at the base of volcanic arcs in orogenic zones, and are controlled by extensive ductile shear zones, complex folds, and dome structures. Host rocks generally exhibit greenschist facies metamorphism. No relation exists between deposit type and granitic intrusions, except for local dikes. This deposit type may be associated with epithermal vein, granitoid- related Au, polymetallic vein, and various Sb and Hg deposits. The deposits type is interpreted to have formed from deep-seated, reducing, hydrothermal-metamorphic fluids. Clastic sediment-hosted Sb-Au (Berger, 1978, 1993) This deposit type consists of stibnite and associated minerals that occur in simple and complex ladder and reticulate veins and veinlets, sometimes with subconformable disseminations. The main ore minerals are stibnite, berthierite, pyrite, arsenopyrite, and gold, with subordinate sphalerite, galena, chalcopyrite, tetrahedrite, chalostibite, scheelite, sphalerite, galena, tetrahedrite, pyrrhotite, marcasite, gudmundite, gersdorffite, native antimony, and native silver. Gangue minerals are mainly quartz and lesser ankerite, and lesser calcite, dolomite, siderite, sericite, and gypsum. Wall rocks are altered to varying combinations of quartz, carbonate, sericite, and pyrite. The host rocks for this deposit are: (1) Archean greenschist derived from mafic and ultramafic volcanic and volcaniclastic rocks; (2) interbedded carbonaceous black shale and volcanogenic-clastic rocks; or (3) to a lesser extent, retrogressively-metamorphosed granitic rocks. The deposit type occurs mainly in linear zones of folding and mylonites associated with regional strike-slip faults. Deposit type is associated with low-grade greenschist facies regional metamorphism; this association suggests a hydrothermal-metamorphic origin. The depositional environment is strongly-deformed fold belts developed along the former intracratonic rift troughs. The deposit type may also be associated with Au-quartz vein deposits. Cu-Ag quartz vein (vein Cu) (Nokleberg and others, 1987) This deposit type consists of Cu sulfides and accessory Ag in quartz veins and disseminations in weakly regionally metamorphosed mafic igneous rocks, mainly basalt and gabbro, and in lesser andesite and dacite. The veins are generally late-stage metamorphic. The deposit minerals include chalcopyrite, bornite, lesser chalcocite, and rare native copper. Alteration minerals include epidote, chlorite, actinolite, albite, quartz, and zeolites. The depositional environment is low-grade metamorphic belts. Kennecott Cu (adapted from basaltic Cu deposit type by D.P. Cox in Cox and Singer, 1986, and from Nokleberg and others, 1987) This deposit type consists of Cu-sulfides in large pipes and lenses in carbonate rocks within a few tens of meters of disconformably underlying subaerial basalt. Subsequent subaerial erosion of Cu-bearing basalt, and low-grade regional metamorphism may concentrate Cu-sulfides into pipes and lenses. The deposit minerals are chalcocite and lesser bornite, chalcopyrite, other Cu sulfide minerals, and oxidized Cu minerals. Alteration minerals are sometimes obscured by, or may include, malachite, azurite, metamorphic chlorite, actinolite, epidote, albite, quartz, zeolites, and secondary dolomite. The depositional environment consists of subaerial basalt overlain by mixed shallow marine and nearshore carbonate sedimentary rocks, including sabkha- facies carbonate rocks. Deposits Related to Surficial Processes: Placer, Paleoplacer, and Laterite Deposits Placer deposits are classified primarily by metals and secondarily by sedimentary processes. The principal sedimentary processes are fluvial and glaciofluvial, shoreline, and eluvial or residual. Fluvial and glaciofluvial deposits form where river velocities lessen at hydraulic flexures, on the inside of meanders, below rapids and falls, and beneath boulders. Shoreline deposits form in areas of strandline accumulations that are caused by shoreline drift, beach storms, wind, and wave actions. Eluvial and residual deposits form by the mechanical and (or) chemical disintegration of bedrock in the general absence of the concentrating force of water. Placer and paleoplacer Au (W.E. Yeend in Cox and Singer, 1986) This deposit type consists of elemental gold as grains and rarely as nuggets in gravel, sand, silt, and clay, and their consolidated equivalents in alluvial, beach, eolian, and rarely in glacial deposits. The major deposit minerals are gold, sometimes with attached quartz, magnetite or ilmenite. The depositional environment is high-energy alluvial where gradients flatten and river velocities lessen as at the inside of meanders, below rapids and falls, beneath boulders, and in shoreline areas where the winnowing action of surf causes gold concentrations found in raised, present, or submerged beaches. Placer Sn (Nokleberg and others, 1987) This deposit type consists of mainly cassiterite and elemental gold in grains in gravel, sand, silt, and clay, and their consolidated equivalents, mainly in alluvial deposits. The depositional environment is similar to that of placer Au deposits. Placer PGE-Au (W.E. Yeend and N.J Page in Cox and Singer, 1986) This deposit type consists of PGE minerals and alloys in grains in gravel, sand, silt, and clay, and their consolidated equivalents in alluvial, beach, eolian, and rarely in glacial deposits. In some areas, placer Au and placer PGE deposits occur together. The major deposit minerals are Pt-group alloys, Os-Ir alloys, magnetite, chromite, and ilmenite. The depositional environment is high-energy alluvial where gradients flatten and river velocities lessen as at the inside of meanders, below rapids and falls, beneath boulders, and in shoreline areas where the winnowing action of surf causes PGE and gold concentrations in raised, present, or submerged beaches. Placer Ti (E.R. Force in Cox and Singer, 1986) This deposit type consists of ilmenite and other heavy minerals concentrated by beach processes and enriched by weathering. The hosting sediment types are medium- to fine- grained sand in dune, beach, and inlet deposits. The depositional environment is a stable coastal region receiving sediment from bedrock regions. The major deposit minerals are low-Fe ilmenite, sometimes with rutile, zircon, and gold. CLASSIFICATION OF LODE MINERAL DEPOSITS INTO METALLOGENIC BELTS This study classifies the lode mineral deposits of the Russian Far East, Alaska, and the Canadian Cordillera into metallogenic belts according to known significant mineral deposits, mineral deposit types, tectonic setting, and tectonic environment. This classification uses the following subdivision of deposits, based on tectonic setting: (1) pre- accretionary deposits that formed early in the geologic history of each tectono-stratigraphic terrane and are thereby unique to each terrane; (2) (syn)accretionary deposits that formed during periods of major structural juxtaposition, regional deformation, and penetrative deformation that generally occurred during collision of now adjacent terranes; and (3) post-accretionary deposits that formed late in the geologic history of groups of terranes, and generally occur in two or more adjacent terranes. The metallogenic belts defined in this report are based on the significant deposits of the region which were selected to be representative of the metallogeny of the region. Other, less well-defined metallogenic belts may be defined for larger groups of relatively small mineral deposits. The major tectonic environments used to characterize metallogenic belts in this study are: (1) accretionary wedge; (2) continental-margin arc; (3) continental rift; (4) island arc; (5) metamorphic; (6) oceanic crust, seamount, and ophiolite; and (7) subduction zone. Definitions of these environments are provided above. The tectonic classifications of lode mineral deposits is currently a topic of considerable debate (Sawkins, 1990); however classification of lode mineral deposits by mineral deposit types and tectonic environment can be extremely useful. These classifications can be used for regional mineral exploration and assessment, for research on the critical or distinguishing characteristics of metallogenic belts, and for synthesizing of metallogenic and tectonic models. To describe the metallogenic belts of the region, the significant lode deposits are classified both according to mineral deposit type and tectonic environment. EXPLANATION OF TABLES ON SIGNIFICANT LODE DEPOSITS AND PLACER DISTRICTS Tabular Descriptions for Sizes of Lode Deposits Size categories for lode mineral deposits, adapted from Guild (1981), are listed below. These size categories define the terms world class, large, medium, and small. These size categories are used mainly in the parts of Table 1 on the lode deposits in the Russian Far East where specific tonnage and grade data are not yet available. The small category may include occurrences of unknown size. Units are metric tons of metal or mineral contained, unless otherwise specified. NOTE: For the following and other tables in this text, the reader is referred to the corresponding word-processing files, either RFENATAB.DOC (Word 6.0 for Windows or Macintosh) or RFENATAB.MCW (Word 5.1 for Macintosh).