USGS Professional Paper 1697 - Alaska Resources Library

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278 Metallogenesis and Tectonics of the Russian Far East, Alaska, and the Canadian Cordillera rocks and the porphyry stock exhibit strong potassic (biotite) alteration, and quartz grains in the porphyry contain abundant, high-salinity fluid-filled inclusions. The deposit is unexplored on the southwest and northeast sides and probably contains a resource of between 5 and 30 million tonnes with average grade between 0.1 to 0.4 percent Cu. Five drill holes totaling 2,359 m explore the deposit; one hole intercepted 150 m averaging 0.25 percent Cu. Aleutian Arc The Aleutian arc, which hosts the Alaska Peninsula and Aleutian Islands metallogenic belt, is composed of Oligocene (post 30 Ma) to Holocene andesite to dacite flows, tuff, and intrusive and extrusive breccia; hypabyssal diorite and quartz diorite and small silicic stocks, dikes, and sills; and volcanic graywacke, shale, and lahars (Burk, 1965; Wilson and Cox, 1983; Wilson, 1985; Wilson and others, 1993; Vallier and others, 1994). To the northeast on the Alaska Peninsula, magmatism apparently started in the late Miocene (about 15 Ma). An older Eocene and Oligocene succession of igneous rock that yields K-Ar ages ranging from 40 to 30 Ma, is located in the northeastern Aleutian Islands and is defined as the Meshik arc by Wilson (1985). Petrologic, chemical, and isotopic characteristics of the Aleutian arc (Miller and Richter, 1994) are as follows: (1) The arc consists predominantly of andesite and low-silica dacite; rhyolite occurs only in a few volcanic centers. (2) The axial part of the central and northeastern parts of the arc is mostly calcalkalic; SiO 2 contents typically range between 50 to 78 percent. (3) Volcanic centers to the southwest are either tholeiitic or transitional to calc-alkalic. (4) The back arc contains alkalic volcanic rocks that occur in widely separated centers. (5) Initial Sr ratios are relatively low, in the range of 0.70305 to 0.7046. The lode deposits of Alaska Peninsula and Aleutian Islands metallogenic belt reflect the bedrock underlying the arc. The northeastern part of the arc on the southwestern part of the Alaska Peninsula is underlain by Mesozoic bedrock of the Peninsular terrane, part of the Wrangellia superterrane (Wilson and Cox, 1983; Nokleberg and others, 1994d). On the Alaska Peninsula, the Peninsular terrane consists of a Late Triassic(?) and Early Jurassic sequence of volcaniclastic and volcanic rocks (Talkeetna Formation), the Middle Jurassic part of the Alaska-Aleutian Range batholith (Reed and Lanphere, 1969, 1973), and younger Cretaceous sedimentary rocks. In contrast, to the southwest, the Aleutian arc is interpreted to be underlain by oceanic crust (Wilson and Cox, 1983; Vallier and others, 1994). The Pyramid Bee, Creek, Rex, and Warner Bay porphyry Cu deposits in the central part of the metallogenic belt occupy a transitional zone between the parts of the magmatic arc underlain by oceanic crust to the southwest and by continental crust to the northeast. Some of the deposits to the northeast are Mo-rich and contain anomalous concentrations of Bi, Sn, and W that may be characteristic of continental-margin deposits (Wilson and Cox, 1983). K-Ar isotopic studies indicate a variable time span of as much as two million years between igneous activity and mineralization. Isotopic studies also indicate sporadic occurrences of mineralization during a long period of igneous activity (Wilson and Cox, 1983). Tectonic Setting for Alaska Peninsula and Aleutian Islands Metallogenic Belt The Aleutian arc, one of the classic igneous continentalmargin arcs along the Circum-Pacific rim, occurs structurally above the Aleutian megathrust, an active subduction zone that dips to the northwest and along that the Pacific Plate is being thrust under the southern margin of Alaska (fig. 126). The tectonic setting and the field, petrologic, chemical, and isotopic data summarized above are used by analogy to infer subduction-zone settings for ancient belts of igneous rocks (Vallier and others, 1994) and their associated granitoid-magmatism metallogenic belts (Nokleberg and others, 1993). Late Tertiary and Quaternary Metallogenic Belts (4 to 0 Ma; figs. 125, 126) Overview The major late Tertiary and Quaternary metallogenic belts in the Russian Northeast, Alaska, and the Canadian Cordillera are summarized in table 3 and portrayed on figures 125 and 126. The major belts are as follows: (1) In the Russian Southeast, the Sakhalin Island (SH) belt, which contains Silica-carbonate, volcanic-hosted Hg deposits, is hosted in shear zones and late Tertiary volcanic rock and is interpreted as related to back-arc spreading behind the Kuril volcanic arc. (2) In the Russian Northeast, the Kuril (KU) belt, which contains granitic-magmatism-related deposits, is hosted in the Kuril volcanic-plutonic belt and is interpreted as forming during subduction-related granitic plutonism that formed the Kuril Island part of Northeast Asia continental-margin arc. (3) Also in the same region, several metallogenic belts continued on from the early and middle Tertiary is the Olyutor (OT) metallogenic belt, which is hosted in the East Kamchatka Volcanic and Sedimentary Basin. (4) In southern Alaska, also continuing on from the middle Tertiary, was the Alaska Peninsula and Aleutian Islands (AP) belt, which contains graniticmagmatism-related deposits and that is hosted in the Aleutian volcanic belt. This metallogenic belt is interpreted as forming during subduction-related granitic plutonism that formed the Aleutian continental-margin arc. (5) In the southern Canadian Cordillera, continuing on from the early and middle Tertiary, was the Owl Creek (OC) belt, which contains granitic-magmatism-related deposits and is hosted in the Cascade volcanicplutonic belt. This metallogenic belt is interpreted during subduction-related granitic plutonism that formed the Cascade continental-margin arc. In the below descriptions of metallogenic belts, a few of the noteable or signficant lode deposits are described for each belt.
Metallogenic-Tectonic Model for Late Tertiary and Quaternary (4 to 0 Ma; fig. 128) During the late Tertiary and Quaternary (Pliocene to the present—4 to 0 Ma), the major metallogenic-tectonic events were and are (fig. 128; table 3) (1) continuation of a series of continental-margin arcs, associated metallogenic belts, and companion subduction-zone assemblages around the Circum- North Pacific, (2) continuation of opening of major sedimentary basins behind major arcs, (3) in the eastern part of the Circum-North Pacific, a continuation of dextral transpression between the Pacific oceanic plate and the Canadian Cordillera margin, (4) a continuation of oblique-orthogonal transpression between the Pacific plate and the southern Alaska, and (5) continuation of sea-floor spreading in the Arctic and eastern Pacific Oceans. The modern geodynamic pattern is defined by interaction of the Eurasian, North American, and Pacific oceanic plates (Cook and others, 1986; Parfenov and others, 1989; Fujita and others, 1997). The pole of rotation between the Eurasian and North American plates is located on, or near the south coast of the Laptev sea in the Russian Northeast (Cook and others, 1986; Larson and others, 1997). POLE OF ROTATION BETWEEN EURASIAN AND NORTH AMERICAN PLATES ? AMUR BLOCK 60 o EURASIAN PLATE ? NSC KE NSV KK UL COLL GK Specific Events for Late Tertiary and Quaternary (1) The Northeast Asia continental-margin arc continues activity. Parts of the arc are in the East Japan volcanic-plutonic belt (ej), the Kuril arc (ku), the Central Kamchatka Volcanic and Sedimentary Basin (kc), and the East Kamchatka volcanic belt (ek). Associated with the arc is subduction of the western edge of the Pacific oceanic plate (PAC) along the Kuril- Kamchatka megathrust (KK) to form the Kuril-Kamchatka (KUK) terrane. A major orthogonal junction occurs between the western end of Aleutian-Wrangell arc (al) and Kamchatka arc (kc). Continuing on or forming anew in the Northeast Asia continental-margin arc are (a) the Sakhalin Island (SH) metallogenic belt, which is hosted in shear zones in late Tertiary and older rock, and is interpreted as forming during back-arc spreading behind Kuril arc, (b) the Central Kamchatka (CK) metallogenic belt, which is hosted in the Central Kamchatka Volcanic and Sedimentary Basin, (c) the East Kamchatka (EK) metallogenic belt, which is hosted in the Central Kamchatka Volcanic and Sedimentary Basin, and (d) the Olyutor (OT) metallogenic belt, which is hosted in the East Kamchatka Volcanic and Sedimentary Basin. The latter three metallogenic 180 o (sp) (sj) OKHOTSK BLOCK SH COLL (kr) COLL ku BERING bs ej BLOCK atb al KU KUK 0 0 NORTHEAST ASIA ARC 800 km 800 mi PAC al PW AP 4 to 0 Ma Middle Tertiary Metallogenic Belts (20 to 10 Ma) (figs. 125, 126) 279 LO ab eb ab ? ? ? (am) bs KA NF cb 80 o COLL al AL DE NAC wr ALEUTIAN- WRANGELL ARC COLLAGE OF RIFTED TERRANES NAM TI YAK COLL PAC METALLOGENIC BELTS AP - Alaska Peninsula and Aleutian Islands KU - Kuril OC - Owl Creek SH - Sakhalin Island NORTH AMERICAN PLATE QC NAC COLLOC EX JF JFR ? CC (cr) ca CASCADE ARC Figure 128. Late Tertiary and Quaternary (Pliocene through present—4 to 0 Ma) stage of metallogenic-tectonic model for the Russian Far East, Alaska, and the Canadian Cordillera and adjacent offshore areas. Refer to text for explanation of metallogenic-tectonic events, to tables 3 and 4 for descriptions metallogenic belts and significant deposits, and to figure 18 for explanation of abbreviations, symbols, and patterns. Adapted from Nokleberg and others (1997b, 1998, 2000).
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USGS Prepared in collaboration with
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U.S. Department of the Interior Gal
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iv Hart River SEDEX Zn-Cu-Ag Deposi
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vi Specific Events for Middle Throu
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viii Metallogenic Belts Formed Duri
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x Origin of and Tectonic Controls f
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xii Toodoggone Metallogenic Belt of
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xiv Slate Creek Serpentinite-Hosted
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xvi Left Omolon Belt of Porphyry Mo
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xviii Origin of and Tectonic Contro
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xx Chukotka Metallogenic Belt of Au
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xxii Plutonic Rocks Hosting East-Ce
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xxiv Skeena Metallogenic Belt of Po
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xxvi Bee Creek Porphyry Cu Deposit
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xxviii 36. Wellgreen gabbroic Ni-Cu
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xxx 87. Partizanskoe Pb-Zn skarn de
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Metallogenesis and Tectonics of the
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format (Nokleberg and others, 1996)
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logenesis of the region (1) subduct
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Subterrane—A fault-bounded unit w
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dilemma consists of two conflicting
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2 to 20 m thick. A related dolomite
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Lantarsky-Dzhugdzhur Metallogenic B
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Origin of and Tectonic Controls for
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Metallogenic Belts Formed During Pr
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as at Oz, Monster, and Tart, may al
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Monashee Metallogenic Belt of Sedim
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Clark Range Metallogenic Belt of Se
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in addition to the Fe deposits. Min
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study) consists of lenses, from 100
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Omulev Austrian Alps W Deposit The
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ock, including coarse clastic rock,
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lative metalliferous brines in a re
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Prince of Wales Island Metallogenic
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suite of deposits and host rocks ar
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margin of the North American Craton
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newly created terranes migrated int
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(Ryazantzeva and Shurko, 1992). The
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tonnes Au and an average grade of a
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mafic and felsic metavolcanic rocks
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intrusion from about 402 to 366 Ma
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mentary rocks of the Cambrian to De
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(Preto and Schiarizza, 1985; Schiar
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ate and clastic rocks and volcanicl
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(Nokleberg and others, 1994c, 1997c
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Berezovka River Metallogenic Belt o
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Finlayson Lake Metallogenic Belt of
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and barite in siliceous black turbi
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Windermere Creek (Western Gypsum) C
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(NX, DL, MY), Viliga (VL), and Zolo
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South of the main east-west-trendin
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ated subduction zone in the Wrangel
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icite-biotite-quartz bodies in frac
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Canada Cordillera. The granitoid ro
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Viliga (VL) passive continental-mar
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32; tables 3, 4) occurs along the n
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superterrane, consists mainly of ma
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ers, 1994c, 1997c). In southern Bri
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mental volcanic rocks of intermedia
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a resource of 34.3 million tonnes o
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potassic zone. Combined estimated p
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and quartz monzodiorite stock and s
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and Omolon (OM) cratonal terranes,
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in volcanic and volcaniclastic rock
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minor calcite, and sporadic pyrite
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supergene blanket are interpreted a
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deposits and occurrences consist of
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onto the Omulevka terrane to form t
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superterrane. This belt is interpre
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to form along the leading edge of t
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quartz, and is virtually not associ
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deposits are at Terrassnoe and Kuna
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Peschanka Porphyry Cu-Mo Deposit Th
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The belt is hosted in the Late Jura
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in a island arc that was tectonical
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and Early Cretaceous Koyukuk island
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The deposit consists of disseminate
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The Orange Hill deposit contains an
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49; tables 3, 4) (Foley and others,
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locally Late Triassic marine volcan
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gold in a gangue of quartz, calcite
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Verkhoyansk granite belt, which int
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metallogenic belts are interpreted
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assemblages, which may have been mo
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during hypogene and supergene alter
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collision and regional thrusting, t
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Yur Au Quartz Vein Deposit The smal
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phase has a Rb-Sr isotopic age of 1
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sian Northeast. The belt is hosted
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Host Granitoid Rocks and Associated
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that are up to 600-1,500 m long, av
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Metallogenic Belts Formed During La
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y partly coeval plutons that range
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tion is interpreted as occuring by
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the Badzhal-Ezop and Khingan parts
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and comagmatic with volcanic rocks;
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as interpreted for the Rock Creek d
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source (Yeo, 1992). The Blow River
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2000). The spatial location of the
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to the east in the central Yukon Te
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occur in a 30-km-long belt along ir
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The Emerald deposit has produced ap
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Metallogenic-Tectonic Model for Ear
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cham oceans were closed, and the Ch
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greisenized Mesozoic granite that i
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composition magmatic bodies (with a
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to Albian pelecypods (Nokleberg and
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quartz-arsenopyrite-pyrrhotite, pol
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thermally altered to siliceous and
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These ore bodies are as much as 1 m
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Eastern Asia-Arctic Metallogenic Be
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Demin, and Krasilnikov, 1974; Nekra
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10 percent Cu, as much as 0.92 perc
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pyrite, pyrite, galena, sphalerite,
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content decreases with depth, as do
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azdelnoye, (2) porphyry Sn deposits
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Karalveem Au Quartz Vein Deposit Th
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Democrat (Mitchell Lode) Granitoid-
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with high-temperature and high-pres
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chalcocite and covellite and also h
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cum-North Pacific, (2) completion o
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(6) In the Paleocene (about 56 to 6
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sists of cinnabar and metacinnabari
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Eastern Asia-Arctic Metallogenic Be
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groups of deposits are interpreted
Page 259 and 260: Indian Mountain and Purcell Mountai
Page 261 and 262: and southeastern Alaska (Moll and P
Page 263 and 264: Nokleberg and others, 1995a; Bundtz
Page 265 and 266: g/t Au or 368.2 Au gold. The deposi
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Page 269 and 270: Mount Nansen porphyry Cu-Mo deposit
Page 271 and 272: A Map 450 500 550 Cross section Dik
Page 273 and 274: Cretaceous and early Tertiary conti
Page 275 and 276: deposits, at Chichagoff and Hirst-C
Page 277 and 278: others, 1994c, 1997c). The signific
Page 279 and 280: tonnes grading 0.53 percent Ni, 0.3
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Page 283 and 284: Bulkley Metallogenic Belt of Porphy
Page 285 and 286: Red Rose W-Au-Cu-Ag Polymetallic Ve
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Page 291 and 292: stocks and dikes, is associated wit
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Page 295 and 296: Specific Events for Early to Middle
Page 297 and 298: of fractured and faulted Permian-Tr
Page 299 and 300: sists of a mineralized fracture zon
Page 301 and 302: dolomite. Wall rock alteration incl
Page 303 and 304: elt of late Tertiary plutons that a
Page 305 and 306: plates that exhibit magnetic anomal
Page 307 and 308: stages (Petrenko, 1999): (1) In the
Page 309: mon. The deposit is of medium size
Page 313 and 314: The origin of the Hg deposits of th
Page 315 and 316: margin or island-arc tectonic envir
Page 317 and 318: Columbia: Implicatons for the Middl
Page 319 and 320: Bazard, D.R., Butler, R.F., Gehrels
Page 321 and 322: Bradley, D.C., Haeussler, P.J., and
Page 323 and 324: Bundtzen, T.K., Laird, G.M., Caluti
Page 325 and 326: Cecile, M.P., 1982, The lower Paleo
Page 327 and 328: Debari, S.M., and Coleman, R.G., 19
Page 329 and 330: U.S. Bureau of Land Management Open
Page 331 and 332: Cordilleran Orogen in Canada: Geolo
Page 333 and 334: Goldfarb, R., Hart, C., Miller, M.,
Page 335 and 336: Grove, E.W., 1986, Geology and mine
Page 337 and 338: Høy, T., 1982a, Stratigraphic and
Page 339 and 340: Jones, D.L., Silberling, N.J., Cone
Page 341 and 342: Kutyev, F. Sh., Baikov, A.I., Sidor
Page 343 and 344: Shield—Ultramafic magma and its m
Page 345 and 346: Manns, F.T., 1981, Stratigraphic as
Page 347 and 348: Miller, M.L., and Bundtzen, T.K., 1
Page 349 and 350: Mortimer, N., 1987, The Nicola Grou
Page 351 and 352: Noble, S.R., Spooner, E.T.C., and H
Page 353 and 354: Canada Annual Meeting, Saskatoon, S
Page 355 and 356: Perello, J.A., Fleming, J.A., O’K
Page 357 and 358: Far East—Mineralogical criteria f
Page 359 and 360: Roeske, S.M., Mattinson, J.M., and
Page 361 and 362:
Schmidt, J.M., and Zierenberg, R.A.
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formation occurrences: Materialy po
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Struik, L.C., 1986, Imbricated terr
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Valuy, G., and Rostovsky, F., 1988,
Page 369 and 370:
Wolfe, W.J., 1995, Exploration and
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Appendix Table 1. Mineral deposit m
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Table 2 Summary of correlations and
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Table 2—Continued Unit(s) and Cor
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Table 2—Continued Unit(s) and Cor
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Table 3—Continued Metallogenic Be
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Table 4. Significant lode deposits,
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Table 4—Continued Appendix 369 De
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Table 4—Continued Tracy Metalloge
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Table 4—Continued Appendix 373 In
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Table 4—Continued Deposit Name Mi
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Table 4—Continued Mainits Metallo
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Table 4—Continued Whitehorse Meta
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Table 4—Continued Appendix 389 LA
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Table 4—Continued Surprise Lake M
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Table 4—Continued Sredinny Metall
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