Rhyolite Geochemical Signatures and Association with ...€¦ · rhyolite suites and volcanogenic massive sulfide (VMS) de-posits was promoted as an effective tool for exploration

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IntroductionFOR MORE than 25 years, the association between specificrhyolite suites and volcanogenic massive sulfide (VMS) de-posits was promoted as an effective tool for exploration.Thurston (1981) and Campbell et al. (1982) first identifiedthis relationship using Archean VMS deposits in the CanadianShield. Lesher et al. (1986) and Barrie et al. (1993) subse-quently developed formal classifications for felsic volcanicrocks based on trace element concentrations and suggestedthat certain types of rhyolites were more prospective for VMSdeposits than others. Recently, Hart et al. (2004) revitalizedthe concept by proposing a conceptual petrogenetic model to

account for the association of specific rhyolite geochemicalsignatures with VMS deposits. The classification geochemi-cally discriminates rhyolites as FI, FII, FIIIa, or FIIIb types.The general conclusions drawn from Lesher et al. (1986),Lentz (1998), and Hart et al. (2004) are that Archean VMSdeposits are hosted mainly by FIII rhyolites, whereas mostpost-Archean VMS deposits are hosted predominantly by FIIrhyolites, and FI rhyolites are unfavorable for VMS mineral-ization. The link between VMS formation (hydrothermal ac-tivity) and rhyolite petrogenesis invokes a particular geody-namic setting and, more specifically, the depth of rhyolitegeneration (Lentz 1998; Hart et al., 2004).

Although exceptions and limitations were recognized, theconcept was rapidly adopted by exploration companies, andrhyolites with the most potential were commonly selectedwithout any consideration for the mineral potential of other

Rhyolite Geochemical Signatures and Association with Volcanogenic Massive SulfideDeposits: Examples from the Abitibi Belt, Canada

DAMIEN GABOURY†

Université du Québec à Chicoutimi, Centre d’études sur les ressources minérales (CERM) and Consortium de recherche en exploration minérale (CONSOREM), 555 boul. de l’Université, Chicoutimi, Québec, Canada G7H 2B1

AND VITAL PEARSON*Consortium de recherche en exploration minérale (CONSOREM), 555 boul. de l’Université, Chicoutimi, Québec, Canada G7H 2B1

AbstractThe relationship between rhyolite geochemistry and volcanogenic massive sulfide (VMS) mineralization has

been proposed as an exploration tool to discriminate prospective felsic volcanic centers. The most widely usedclassification discriminates between four types of rhyolite: FI, FII, FIIIa, and FIIIb. The FI rhyolites are calc-alkaline, with strongly fractionated REE patterns and strongly negative Ta and Nb anomalies. They are usuallyconsidered barren, unless associated with FII or FIII felsic volcanic rocks. The FII rhyolites are calc-alkalineto transitional with moderately fractionated REE patterns and moderate Ta and Nb anomalies. They rangefrom barren to having a high potential to host VMS mineralization. The FIIIa and FIIIb rhyolites are tholei-itic and show weakly fractionated REE patterns and weak to absent Nb and Ta anomalies. They have the high-est potential to host VMS mineralization. The FIIIb rhyolites are high-temperature rhyolites with flat REE pat-terns and no Ta or Nb anomalies.

The Abitibi greenstone belt, especially in Quebec, is well known for its abundant and diverse VMS deposits.Representative samples of VMS-associated rhyolites within and outside of mining districts, including the clas-sic Noranda VMS district, were analyzed for major and trace elements to validate their proposed favorabilityfor hosting VMS deposits. Results indicate that all of the rhyolite types are prospective, but mineralizationmay differ from the classic Noranda-type VMS deposit. The FI-type rhyolites appear to be particularly asso-ciated with gold-rich VMS deposits, such as the world-class Laronde deposit, and are more prospective forCu-Au replacement and vein-type deposits. The FII-type rhyolites account for about 70 percent of rhyolitesin the Abitibi belt. Although considered less prospective, some districts dominated by FII rhyolites, such asVal-d’Or and Selbaie, have collectively produced in excess of 100 million metric tons (Mt) of ore. Deposits inthese districts mainly consist of sulfide veins and disseminated ore with low Cu and Zn grades and are asso-ciated with abundant and highly vesicular volcaniclastic rocks that display a compositional continuum fromandesite to rhyolite. Other weakly mineralized FII districts (e.g., Hunter mine, Gemini-Turgeon) are charac-terized instead by bimodal flow-dome sequences. The FIIIa-type rhyolites occur mainly in the Noranda dis-trict and form flow-dome complexes in bimodal sequences with associated Noranda-type VMS mineralization.In small felsic centers (Joutel, Normétal, Chibougamau, Quévillon) that show a volcanic evolution from FIIIato FII to FI affinities, VMS deposits are directly associated with FIIIa rhyolites, thus demonstrating the use-fulness of rhyolite geochemistry for exploration in these areas. The FIIIb rhyolites are rare in the Abitibi belt,with most occurring in the Matagami district where they are associated with Zn-Cu VMS deposits. Based onthis analysis, we suggest that a combination of rhyolite geochemistry, volcanic facies, and style of the miner-alization may be more meaningfully applied in exploration than rhyolite type alone, particularly in the case ofFI and FII rhyolites.

† Corresponding author: e-mail, [email protected]*Present address: Mines Virginia Inc., 116 St-Pierre, Suite 200, Québec,

Québec, Canada G1K 4A7.

©2008 Society of Economic Geologists, Inc.Economic Geology, v. 103, pp. 1531–1562

rhyolites in the vicinity. Recently, the discovery of the world-class, gold-rich VMS Laronde deposit in FI and FII rhyolites(Mercier-Langevin et al., 2007a, b) raised some doubt aboutthe application of rhyolite classification in VMS exploration.

The Archean Abitibi belt is one of the most prolific VMSbelts in the world (Rodney et al., 2002), hosting various typesof VMS and volcanogenic gold deposits. Consequently, thisbelt constitutes an ideal laboratory for testing the validity ofrhyolite classification as a means for finding ore deposits. Inthis paper, we reassess the use of rhyolite classification as anexploration tool in the Abitibi greenstone belt and present acompilation of the characteristics of ore-hosting rocks, alter-ation types, and volcanic facies. Felsic volcanic rocks in andaround VMS districts in the Abitibi belt of Quebec were sam-pled and analyzed for major and trace elements. Rhyoliteswere classified using the parameters of Hart et al. (2004) andcompared with VMS tonnages, mineralization type, and vol-canic rock characteristics. This approach permits a semiquan-titative comparison of the favorability of various rhyolite types.

Geology of the Abitibi BeltThe Abitibi greenstone belt in Canada (Fig. 1) is the largest

and best preserved Archean belt (Card, 1990) and also one ofthe richest VMS-bearing belts in the world (Rodney et al.,2002). These include syngenetic VMS and gold-rich VMS de-posits, as well as sulfide-rich, gold-bearing quartz veins andCu-Au–bearing sulfide veins. All are genetically associatedwith felsic volcanic complexes (e.g., Chartrand and Cattalani,1990). The Abitibi belt includes three of the world’s largestand richest VMS deposits (>50 Mt of ore)—Kidd Creek,Horne, and Laronde—of which the last two are gold rich.Eight other large deposits (>15 Mt) also have been mined:Selbaie, Mattagami Lake, Bouchard-Hébert, Louvicourt,East Sullivan, Bousquet-1, Dumagami-Bousquet-2, and Qué-mont. Overall, more than 80 deposits are known, totalingmore than 675 Mt of metallurgically high-quality Cu ± Zn ±Ag ± Au ore (Hannington et al., 1999a; Rodney et al., 2002).

The Abitibi greenstone belt is a linear east-trending vol-cano-sedimentary sequence intruded by plutonic suites (Fig.1). It is thought to have developed through arc formation, arcevolution, arc-arc collision, and arc fragmentation datingfrom 2735 to 2670 Ma (Mueller et al., 1996; Daigneault et al.,2004). Wyman et al. (2002) proposed that the Abitibi-Wawagreenstone belt is the product of subduction tectonics, en-hanced and modified by mantle plume interaction. The beltis broadly divided into the 2735 to 2705 Ma North Volcaniczone and the 2715 to 2697 Ma Southern Volcanic zone(Chown et al. 1992), although more recent compilations pre-sent a more complex evolution (e.g., Ayer et al., 2003, 2005;Goutier and Melancon, 2007). The east-trending Porcupine-Destor-Manneville fault separates the Northern and South-ern Volcanic zones, and the Cadillac-Larder Lake fault de-fines the southern boundary of the Southern Volcanic zone(Fig. 1). In addition, the North Volcanic zone is also dividedinto external (NVZ-ext) and internal (NVZ-int) segments(Fig. 1) separated by the linear, east-trending Chicobi sedi-mentary sequence (Daigneault et al., 2004).

Three main volcanic cycles are recognized in the Quebecsegment (Daigneault et al., 2004). Cycle 1, from 2735 to 2720Ma, corresponds to a subaqueous basaltic plain punctuated

by several isolated felsic centers, such as Joutel, Normétal,Matagami, Gemini, Selbaie, Hunter, and Chibougamau(Lemoine). All these felsic centers have well-documentedsynvolcanic intrusions (Gaboury, 2006), felsic domes andlavas, and associated VMS mineralization. Cycle 2, from 2720to 2705 Ma, is interpreted as an emerging and evolving arc, towhich some synvolcanic plutons have been linked (Chown etal., 1992), such as the Chibougamau pluton with its Cu-Auvein-type deposits, the Kamiskotia pluton (Barrie and Davis,1990) with VMS deposits in associated felsic lavas, and theMountain pluton, which has been indirectly dated at 2718 Mabased on the age of cogenetic felsic lavas at the Langlois VMSmine (Davis et al., 2005). The 2717 to 2711 Ma rhyolites atKidd Creek (Bleeker et al., 1999) are compositionally distinctfrom these other cycle 2 felsic rocks due to their high silicacontents and their REE-HFSE patterns comparable to rhyo-lites from the Iceland rift zone (Prior et al., 1999). The KiddCreek VMS deposit is also exceptional due to its size andmetal content (Hannington et al., 1999a), as well as the ap-parent lack of an association with a synvolcanic intrusion(Barrie et al., 1999). Cycle 3 is restricted to the Southern Vol-canic zone and is interpreted as arc volcanism (e.g.,Daigneault et al., 2004). The Southern Volcanic zone includesthe Blake River Group (2703–2698 Ma) and the Malartic seg-ment (2714–2701 Ma). The Blake River is thought to repre-sent the development of a multiphase megacaldera, recentlyproposed by Pearson and Daigneault (2009), which hostsmajor VMS deposits associated with three main synvolcanicintrusions, the Flavrian-Powell, Cléricy, and Mooshla intru-sions and associated felsic rocks. The Malartic segment hasrecorded a complex evolution (Scott et al., 2002) involving ko-matiitic rifting at the base (2714 Ma) followed by arc evolu-tion and later arc rifting (2705–2701). The VMS deposits ofthe Val-d’Or mining district occur specifically in the arc-re-lated volcanic sequence (Scott et al., 2002) associated withthe synvolcanic Bourlamaque pluton (Fig. 1).

Daigneault et al. (2004) determined that the deformationhistory is diachronous: 2710 to 2690 Ma in the North Volcaniczone and 2698 to 2640 Ma in the Southern Volcanic zone butfollowing the same pattern for both. In each case, the firstphase consisted of north-south deformation dominated byshortening that induced thrusting along major east-trendingboundary faults (the Porcupine-Destor-Manneville andCadillac-Larder Lake faults), folding, and the development ofa regional east-trending schistosity. The second phase was adextral, transpressional late-stage increment responsible fordextral movement along major east-trending faults (theDestor-Manneville and Cadillac-Larder Lake faults) and thedevelopment of a southeast-trending fault system. Syntec-tonic intrusions were emplaced locally during all stages of thedeformation history. As a consequence of this structural evo-lution, VMS-hosting sequences or districts occur as (1) mon-oclinal laterally extensive and tilted sequences located strati-graphically above their synvolcanic pluton, as exemplified bythe Normétal, Val-d’Or, Bousquet, Selbaie, Chibougamau(Lemoine), Langlois, and Gemini mining districts; (2) as se-quences occurring on both flanks of an anticline centered ona synvolcanic intrusion, such as those found in the Noranda,Matagami, and Hunter districts; or (3) as a complexly foldedsequence, such as the Joutel district.

1532 GABOURY AND PEARSON

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RHYOLITE GEOCHEMICAL SIGNATURES AND ASSOCIATION WITH VMS, ABITIBI BELT, CANADA 1533

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Methodology

Sampling

During the summer of 2003, more than 120 felsic rocks(mainly rhyolite with minor quantities of dacite) were sam-pled from outcrop, with another four taken from drill cores(App. 1; Figs. 1–5). Four samples also were collected during

earlier visits to mines with deposits of interest. The aim wasto obtain a uniform sample dataset analyzed as one batchusing the best analytical procedures, thus avoiding compar-isons between different data sources representing a variety ofanalytical techniques, variable detection limits, and incom-plete analyses. The volcanic facies was taken into considera-tion when selecting samples. For example, in lobed felsic vol-canic domes and flows, only the lobe center or the massivefacies was sampled to reduce the possible influence of hy-drothermal alteration. The goal of the sampling strategy wasto compare (1) VMS-hosting rhyolites to surrounding rhyo-lites, (2) rhyolites from different mining districts, and (3) rhy-olites from areas considered relatively nonprospective forVMS deposits to rhyolites from known VMS districts. Aspecial emphasis was given to rhyolites associated with docu-mented atypical (vein and disseminated) gold-rich vol-canogenic deposits (e.g., Géant Dormant, Comtois, Agnico-Telbel, Duvan). Furthermore, dated rhyolites and felsic tuffswere also sampled to provide a temporal framework for theevolution of the felsic volcanism.

Geochemical analysis

All samples were processed at the Université du Québec àChicoutimi where they were cleaned to remove surfaceweathering, crushed, and then pulverized using an aluminashatter box. The shatter box was cleaned with quartz betweeneach sample and precontaminated with each new sample tominimize sample-to-sample contamination. The powderedsamples were shipped to the Geo Labs facility in Sudbury asone batch. The major elements were analyzed using wave-length-dispersive X-Ray florescence (WXRF) on fused pellets.


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R-54

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5 km

R-52

R-51

R-53Persévérence

Matagami

Bell River

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Mafic volcanic rocks

Intrusive rocks

VMS deposit

Mine (active or closed)

Road

Town

Sample: FIIIb

Lac Mattagami

N

Bracemac

McLeod

FIG. 2. Simplified geologic map of the Matagami district, showing sampleand VMS deposit locations. Map modified from Piché et al. (1993).

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VMS deposit


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FIG. 3. Simplified geologic map of the Noranda district, showing sample and VMS deposit locations. BRG = Blake RiverGroup. Map modified from Pearson and Daigneault (2009).

Trace elements were determined by ICP-MS following aclosed-beaker digestion method involving four acids over twoweeks to ensure total digestion of all minerals. Three repli-cates and one reference sample were included in the batch.The precision and accuracy of the analytical values were ex-cellent, including the results for potentially problematic Zr(standard deviation of <0.05% for trace elements). The ana-lytical results used in this study are provided in Appendix 1.

Petrographic studyThin sections were made from all samples except for those

from drill core and samples of insufficient size (App. 2). Thegoal of the petrographic study was to establish, (1) the per-centage and size of phenocrysts, (2) the nature of any offeldspar phenocryst alteration, and (3) the mineral assem-blage, overall composition, and intensity of the quartz-feldspar matrix alteration.


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Agnico-Telbec

Poirier

Joutel Copper

R-46

R-48

R-47

R-45R-44

Joutel

Explo Zinc

Valrenne

5 km

La Sarre

Lyndhurst

Normétal

Duvan

Hunter

R-38

R-41

R-40

R-39

R-66 R-65

R-64

R-63R-62

R-57R-58

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R-61R-60

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R-36R-35

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R-56R-55

Poularies

10 km

Quévillon

Comtois

R-8

R-3

R-2

R-1R-9

R-6

Langlois

R-4R-5

Mountain

5 km



VMS deposit

Mine (active or closed) Road Town

sample: FI

Intrusive rocks

Sedimentary rocks

Major fault

A Chibougamau

Lemoine

R-108

R-109

R-113R-111

R-112

R-110

Chibougamau

Lac Doré

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WF

WFWF

5 km

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C DNVC

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sample: FII

sample: FIIIa

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FIG. 4. Simplified geologic map, showing sample and VMS deposit locations. A. Joutel (modified from Legault et al.,2002). JVC = Joutel Volcanic Complex. B. Chibougamau (modified from Daigneault and Allard, 1990). WF = Waconichi For-mation. C. Normétal (upper part: modified from Lafrance et al., 2000) and Hunter (lower part: modified from Mueller andDonaldson (1992). HMG = Hunter Mine Group, NVC = Normétal Volcanic Complex. D. Quévillon area (modified fromLacroix et al., 1993).

Assessment of Rhyolite Type Versus VMS PotentialAssessing exploration vectors and prospectiveness indicators

based on the presence of mineralization, number of deposits,and total ore tonnage is limited by the current state of knowl-edge and assumes that discovered orebodies represent high po-tential, and undiscovered mineralization represents low poten-tial. Sampling bias is another limiting constraint because it is

difficult to obtain a uniform sampling pattern. The VMS dis-tricts, particularly the best studied ones, are invariably oversam-pled, whereas smaller or remote districts are commonly under-represented, as are other areas considered to have low potential.Although it is impossible to overcome all these limitations, thisstudy has the advantage of including a wide range of felsic vol-canic rocks, whether associated with VMS mineralization or not.


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R-13

Val d'Or

Louvicourt

Akasaba

Dunraine

ManitouBarvu

East SullivanR-15

R-14

R-10R-12

R-11

R-116

R-18

R-19

R-17

R-20R-16

Abcourt

Lamorandière

Jay Copper

Vendome

Lyndhurst

Amos

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R-40 R-43

R-32

R-31

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R-65R-66

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R-23

VDF

HF

Bourlamaque

CLLF

PDMF

Kinojevisformation

Chicobi

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5 km


Mafic volcanic rocks VMS deposit


Road

Town

Sample: FI

Intrusive rocks

Sedimentary rocks Major fault

B

A

R-25

Sample: FII

Sample: FIIIa

10 km

N

N

R-28

FIG. 5. A. Simplified geologic map, showing sample and VMS deposit locations. B. Val-d’Or district (modified from Scottet al., 2002). CLLF = Cadillac-Larder Lake fault, HF = Heva Formation, VDF = Val-d’Or Formation. B. External NorthVolcanic zone (NVZ) area (modified from Chown et al., 1992). PDMF = Porcupine-Destor-Manneville fault.

In the following sections, mining districts and areas of in-terest are described and classified in terms of predominantrhyolite-VMS associations, with rhyolite types determined ac-cording to parameters of Hart et al. (2004). Although our ap-proach uses informal subdivisions of mining districts, effusivecenters, and geographic sectors that may have multiple felsichorizons, and in some cases, various rhyolite types, it has nu-merous advantages described above.

The geochemical signatures of rhyolites directly associatedwith VMS and VMS-related mineralization are compared toother rhyolites from the same district, referred to here as“background rhyolites,” in an attempt to uncover any geo-chemical trends within districts. Tonnage values for the vari-ous districts were compiled using data from Chartrand andCattalani (1990), Lacroix (1998), and Hannington et al.(1999a), in addition to data from companies where necessary.Ore, alteration, and volcanic host-rock characteristics werealso compared (Tables 1, 2).

To overcome the effect of hydrothermal alteration in classi-fying the rhyolite samples, only HFSE and REE were used.Some altered rhyolite (or dacite) samples in the footwall andlateral to VMS deposits have major element concentrationsranging from apparent andesite (<63%) to high-silica rhyolite(>80% SiO2). Even trace elements (LREE) reputed to be im-mobile show some variations in strongly altered footwall rocksand these particular samples are identified in the text. Itshould be noted, however, that with the exception of theseanomalous altered rhyolites, most samples display no differ-ences in REE and HFSE concentrations compared to thebackground rhyolites and are thus considered suitable for thepurpose of this study.

Rhyolite Classification and PetrogenesisFour types of rhyolite are identified by Lesher et al. (1986):

FI, FII, FIIIa, and FIIIb. The FIV-type rhyolites (Hart et al.,2004) are virtually absent from Archean suites and are notdiscussed. The FI rhyolites are alkaline to calc-alkaline, withstrongly fractionated REE patterns and strongly negative Taand Nb anomalies. They are considered barren to rarely fa-vorable for hosting VMS deposits. The FII rhyolites are calc-alkaline to transitional (following the nomenclature of Barrettand MacLean, 1994), with moderately fractionated REE pat-terns and moderate Ta and Nb anomalies. They are consid-ered moderately favorable for hosting VMS deposits. TheFIIIa and FIIIb rhyolites are tholeiitic and considered tohave the greatest potential for hosting VMS deposits. TheFIIIa rhyolites show weakly fractionated REE patterns andweak to nonexistent Nb and Ta anomalies. The FIIIb rhyo-lites are high-temperature rhyolites with flat REE patternsthat lack Ta and Nb anomalies.

Recently, Hart et al. (2004) linked the geochemical signa-tures of various rhyolite types to partial melting depths withina rift environment. The FI, FII, and FIII magmas are inter-preted as having equilibrated with garnet-bearing residua at adepth of >30 km, with amphibole-plagioclase residua at 30 to10 km, and with plagioclase-dominant, garnet-amphibole–free residua at <15-km depth, respectively.

Hart et al. (2004) provided a list of compositional ranges todiscriminate between the four rhyolite types. Four of themost useful elements are Zr, Y, La, and Yb because they are

generally immobile during hydrothermal alteration and arerepresentative of petrogenetic processes. These elementswere used to create Zr/Y versus Y and [La/Yb]CN versus YbCN

(chondrite-normalized: Nakamura, 1974) binary classificationdiagrams (Lesher et al., 1986; Barrie et al., 1993; Lentz,1998). A drawback of these classification parameters is theoverlap of some discriminating compositional ranges for thevarious rhyolite types. When plotted on the binary diagrams(Fig. 6), only 61 percent of the samples fall into the same clas-sification field on both plots. To overcome this discrepancy,primitive mantle-normalized multielement plots were used inthis study. These plots allow for better discrimination be-tween rhyolite signatures, and distinguishing features, such asnegative Nb and Ta anomalies associated with subductionprocesses, Eu anomalies, and degree of REE fractionation,can be better visualized (e.g., Sun and McDonough, 1989;Kerrich and Wyman, 1997).

FIIIb RhyolitesThe FIIIb rhyolites are defined as tholeiitic high-silica,

high-temperature rhyolites with flat rare earth element(REE) patterns expressed by [La/Yb]CN chondrite-normal-ized values of 1.1 to 4.9, high concentrations of high fieldstrength elements (Y, Zr, Hf, and HREE), low Zr/Y ratios,pronounced negative Eu anomalies, and a lack of subduction-related anomalies such as Nb and Ta (Hart et al., 2004). Thistype of rhyolite was initially identified at Kidd Creek,Kamiskotia, and in the Matagami district (Lesher et al., 1986).

Matagami mining district

The Matagami area (Fig. 2) is an important VMS districtwith total past production and current reserves of more than 50Mt of ore from 12 deposits, including the 5-Mt Zn-Cu Perse-verance deposit presently under development (Xstrata Zinc).The volcanic succession is folded along the open northwest-plunging Galinée anticline (Sharpe, 1968), which is centeredon the synvolcanic Bell River intrusion. The south flank is alow-strain domain with the volcanic sequence facing and dip-ping 45º south, whereas the north flank is a highly strained,steeply dipping domain (Piché et al., 1993). The stratigraphicsuccession comprises the 2721 Ma (Mortensen et al., 1993)rhyolitic Watson Lake Group at the base overlain by thebasaltic Wabasse Group (Beaudry and Gaucher, 1986). TheWatson Group consists of a 1,000-m-thick sequence of felsiclava flows representing the footwall of VMS deposits in the re-gion, with the exception of the newly discovered Bracemac andMcLeod deposits. All the deposits, except Bracemac andMcLeod, lie along a cherty and sulfide-enriched unit called theKey tuffite at the interface of both groups (Piché et al., 1993).

The south and north flanks of the Watson Group were sam-pled from: (1) the underground footwall at the Bell-Allardmine, (2) a surface stripping of the rhyolite hosting the Per-severance deposit, (3) the location of the rhyolite for whichMortensen et al. (1993) determined a geochron U-Pb age of2721 Ma (sample R-53 in this study), and (4) rhyolites northof the town (Fig. 2). All four samples have flat HFSE-REEpatterns as previously documented by Lesher et al. (1986)and Barrie et al. (1993), and the pattern for the Bell-Allardfootwall rhyolite sample is the same as the pattern for theother three (Fig. 7).


0361-0128/98/000/000-00 $6.00 1537


0361-0128/98/000/000-00 $6.00 1538

TAB

LE

1. C

hara

cter

istic

s of

Hos

t Vol

cani

c Se

quen

ces

in S

elec

ted

VM

S D

istr

icts

Are

aG

roup

Volc

anic

sty

leVe

sicu

lari

tyVo

lcan

ic h

iatu

sF

elsi

c co

mpo

sitio

n ev

olut

ion

Intr

usio

nR

efer

ence

Mat

agam

iF

IIIb

Bim

odal

maf

ic-f

elsi

c, lo

bate

fels

ic la

va

Low

-med

ium

Key

tuff

ite: m

ain

Hom

ogen

eous

at t

he

Bel

l Riv

erPi

ché

et a

l. (

1993

)flo

ws

with

mul

ticen

tere

d co

ales

cent

ho

rizo

n ho

stin

g di

stri

ct s

cale

volc

anis

m fo

rmin

g a

unit

of r

egio

nal

all d

epos

itsex

tent

, wel

l-doc

umen

ted

synv

olca

nic

faul

ts

Nor

anda

FII

IaB

imod

al m

afic

-fel

sic

volc

anis

m w

ith

Low

Mul

tiple

che

rt

Hom

ogen

ous

at th

e C

leri

cyK

err

and

mul

tiple

isol

ated

to lo

cally

coa

lesc

ent

hori

zons

def

inin

g di

stri

ct s

cale

Fla

vria

nG

ibso

n (1

993)

fels

ic c

ente

rs, d

omin

ated

by

loba

te fe

lsic

m

ultip

le v

olca

nic

Pow

ell

lava

flow

s; w

ell-d

ocum

ente

d sy

nvol

cani

c cy

cles

faul

ts, s

ome

of r

egio

nal e

xten

t

Jout

elF

IIIa

Bim

odal

vol

cani

sm d

omin

ated

by

loba

te

Low

Che

rty

hori

zons

E

volu

tion

from

thol

eiiti

c Va

lren

neL

egau

lt et

al.

(200

2)fe

lsic

lava

s w

ith le

sser

tuff

aceo

us r

ocks

(not

wel

l-del

inea

ted

to tr

ansi

tiona

l to

calc

-alk

alin

ere

gion

ally

)

Nor

mét

alF

IIIa

Rift

-rel

ated

bim

odal

vol

cani

sm d

omin

ated

L

owB

ande

d ir

on

Evo

lutio

n fr

om tr

ansi

tiona

l U

nkno

wn

Laf

ranc

e et

al.

(200

0)by

flow

s an

d le

sser

cla

stic

faci

es; i

sola

ted

form

atio

n at

the

top

to th

olei

itic

fels

ic c

ente

rs a

long

syn

volc

anic

faul

ts

of th

e ho

st u

nit

bord

erin

g ri

ft m

argi

ns

Qué

villo

nF

IIIa

Stro

ngly

def

orm

ed b

imod

al s

eque

nces

L

ow to

non

eN

ot d

ocum

ente

dVa

riab

le a

t the

dis

tric

t sca

le,

Mou

ntai

nL

acro

ix e

t al.

(199

3)w

ith p

oorl

y pr

eser

ved

volc

anic

faci

es

num

erou

s fe

lsic

hor

izon

san

d ar

chite

ctur

e

Val-d

’Or

FII

And

esite

to r

hyol

ite, v

olca

nicl

astic

-H

igh

Loc

al fi

ne-g

rain

ed

Sim

ilar

at th

e di

stri

ct s

cale

B

ourl

amaq

ueSc

ott e

t al.

(200

2)do

min

ated

vol

cani

sm w

ith lo

cal d

omes

se

dim

ents

and

lava

flow

s pr

oxim

al to

eff

usiv

e ce

nter

; mul

ticen

tere

d co

ales

cent

vo

lcan

ism

Selb

aie

FII

And

esite

to r

hyol

ite, v

olca

nicl

astic

-H

igh

Loc

al p

yrite

-ric

h Si

mila

r at

the

dist

rict

sca

le

Bro

uilla

nL

arse

n an

d do

min

ated

vol

cani

sm w

ith lo

cal d

ome

sedi

men

tsH

utch

inso

n (1

993)

and

lava

flow

s pr

oxim

al to

eff

usiv

e ce

nter

; mul

ticen

tere

d co

ales

cent

vo

lcan

ism

Hun

ter

FII

Cal

dera

-rel

ated

bim

odal

seq

uenc

e,

Low

to n

one

Ban

ded

iron

Si

mila

r at

the

dist

rict

sca

le

Poul

arie

sM

uelle

r an

d ab

unda

nt fe

lsic

flow

s, la

rge

disc

orda

nt

form

atio

n at

the

top

Mor

tens

en (

2002

)fe

lsic

dik

e sw

arm

of th

e ho

st u

nits

Bou

sque

tF

I an

d F

IIA

ndes

ite to

rhy

odac

ite, v

olca

nicl

astic

-H

igh

Non

eSi

mila

r at

the

dist

rict

sca

le

Moo

shla

Laf

ranc

e et

al.

(200

3)do

min

ated

vol

cani

sm w

ith lo

cal d

ome

and

lava

flow

s pr

oxim

al to

eff

usiv

e ce

nter

s; m

ultic

ente

red

coal

esce

nt

volc

anis

m


0361-0128/98/000/000-00 $6.00 1539

TAB

LE

2. C

hara

cter

istic

s of

VM

S D

epos

its in

Sel

ecte

d D

istr

icts

Are

asG

roup

Mai

n de

posi

tsM

etal

sM

iner

aliz

atio

n st

yle

Alte

ratio

nR

efer

ence

Mat

agam

iF

IIIb

Mat

taga

mi L

ake

Zn-C

u-A

gM

assi

ve s

trat

iform

exh

alat

ive

sulfi

de le

nses

abo

ve a

C

hlor

iteL

aval

lière

(19

95)

Bel

l-Alla

rdre

gion

al c

hert

y ho

rizo

n w

ith w

ell-d

efin

ed u

nder

lyin

g Ta

lcPe

rsev

eran

cedi

scor

dant

str

inge

r zo

nes

Seri

cite

Nor

anda

FII

IaQ

uém

ont

Cu-

Zn-A

u-A

gM

assi

ve s

trat

iform

exh

alat

ive

sulfi

de le

nses

abo

ve

Chl

orite

Ker

r an

d A

nsil

regi

onal

che

rty

hori

zons

with

wel

l-def

ined

und

erly

ing

Seri

cite

Gib

son

(199

3)C

orbe

tdi

scor

dant

str

inge

r an

d al

tera

tion

zone

s

Nor

anda

FII

Ia

Hor

neC

u-A

uC

igar

-sha

ped

mas

sive

sul

fide

lens

es r

epla

cing

fels

ic

Seri

cite

Mac

Lea

n an

d F

IIvo

lcan

icla

stic

roc

ks w

ith a

ssoc

iate

d su

lfide

str

inge

r zo

nes

Silic

ifica

tion

Hoy

(19

91)

(H z

ones

); su

lfide

dis

sem

inat

ion

and

repl

acem

ent o

f ±

Chl

orite

fels

ic v

olca

nicl

astic

roc

ks (

Zn-r

ich

zone

5)

Jout

elF

IIIa

Poir

ier

Zn-

Cu-

Ag

Fol

ded

mas

sive

sul

fide

lens

es w

ith b

edde

d py

rite

hos

ted

Chl

orite

Leg

ault

et a

l. (2

002)

Jout

el C

oppe

rin

mas

sive

to b

recc

iate

d an

d ch

erty

rhy

olite

with

ass

ocia

ted

Seri

cite

disc

orda

nt C

u-ri

ch s

trin

ger

zone

s in

chl

oriti

c al

tera

tion

Silic

ifica

tion

Nor

mét

alF

IIIa

Nor

mét

alZn

-Cu-

Au-

Ag

Stro

ngly

def

orm

ed, v

ertic

ally

plu

ngin

g, c

igar

-sha

ped

Chl

orite

Laf

ranc

e (2

003)

Nor

met

mar

sulfi

de le

nses

Seri

cite

Fe-

carb

onat

e

Qué

villo

nF

IIIa

Lan

gloi

sZn

-Cu-

Au-

Ag

Stro

ngly

def

orm

ed a

nd tr

ansp

osed

as

vert

ical

tabu

lar

sulfi

de le

nses

; C

hlor

iteL

acro

ix e

t al.

(199

3)

Zone

97

very

wea

k pr

eser

vatio

n of

ori

gina

l vol

cani

c ch

arac

teri

stic

sSe

rici

te

Val-d

’Or

FII

Lou

vico

urt

Cu-

Zn, A

u-A

gM

ostly

dis

sem

inat

ed s

ulfid

es a

nd a

ssoc

iate

d m

assi

ve r

epla

cem

ent-

Chl

orite

Jenk

ins

and

Eas

t Sul

livan

type

pod

s an

d le

nses

; no

reco

gniz

ed w

ell-d

efin

ed d

isco

rdan

t Se

rici

teB

row

n (1

999)

Man

itou-

Bar

vue

stri

nger

zon

e or

che

rt; m

iner

aliz

atio

n oc

curs

at v

ario

us s

trat

igra

phic

F

e-ca

rbon

ate

leve

ls a

t the

dis

tric

t sca

le

Selb

aie

FII

Zone

A1,

A2,

BC

u-Zn

-Au-

Ag

Mas

sive

sul

fide

Cu-

and

Au-

rich

dis

cord

ant l

ense

s (A

2 an

d B

), C

hlor

iteL

arse

n an

d di

ssem

inat

ed a

nd s

trin

ger

Zn-r

ich

sulfi

de m

iner

aliz

atio

n in

fels

ic

Seri

cite

Hut

chin

son

(199

3)vo

lcan

icla

stic

roc

ks, m

assi

ve c

onco

rdan

t pyr

itic

lens

es o

f low

Si

licifi

catio

ngr

ade

(A1)

Hun

ter

FII

Hun

ter

Cu-

Zn-A

u-A

gC

onco

rdan

t, ex

hala

tive

mas

sive

sul

fide

lens

es w

ith u

nder

lyin

g C

hlor

iteB

onne

au (

1992

)L

yndh

urst

disc

orda

nt s

trin

ger

zone

s; d

epos

its a

re a

t the

top

of th

e vo

lcan

ic

Seri

cite

pile

nea

r ir

on fo

rmat

ions

and

sed

imen

ts

Bou

sque

tF

I an

d F

IIL

aron

deA

u-C

u-Zn

-Ag

Rep

lace

men

t-ty

pe g

old-

rich

sul

fide

lens

es in

vol

cani

clas

tic h

oriz

ons,

A

lum

inou

sM

erci

er-

Bou

sque

t 1 a

nd 2

Au-

Cu

no a

ssoc

iate

d ch

ert,

no d

isco

rdan

t str

inge

r zo

ne; m

iner

aliz

atio

n C

hlor

iteL

ange

vin

(200

5)D

umag

ami

occu

rs a

t var

ious

str

atig

raph

ic le

vels

at t

he d

istr

ict s

cale

Seri

cite

Jout

elF

IA

gnic

o-Te

lbel

Au-

Ag

Dis

sem

inat

ed to

mas

sive

ban

ds o

f gol

d-be

arin

g py

rite

Fe-

carb

onat

eG

auth

ier

et a

l. (2

003)

Chl

orite

Seri

cite

Qué

villo

nF

IC

omto

isA

u-A

gD

isse

min

ated

to s

trin

ger-

styl

e go

ld-b

eari

ng p

yriti

c m

iner

aliz

atio

nA

lum

inou

sD

upré

et a

l. (2

002)

NV

Z-in

t1F

IG

éant

Dor

man

tA

u-A

g (C

u, Z

n)Va

riab

ly o

rien

ted

sulfi

de-r

ich

quar

tz v

eins

Chl

orite

Gab

oury

and

Se

rici

teD

aign

eaul

t (19

99)

NV

Z-ex

t1F

ID

uvan

Cu-

Ag

Dis

sem

inat

ed to

mas

sive

ban

ds o

f pyr

ite w

ith a

bund

ant m

agne

tite

Chl

orite

Trem

blay

et a

l. (1

996)

host

ed in

tuff

aceo

us v

olca

nicl

astic

roc

ks

Seri

cite

1 A

bbre

viat

ions

: NV

Z-ex

t = e

xter

nal N

orth

Vol

cani

c zo

ne, N

VZ-

int =

inte

rnal

Nor

th V

olca

nic

zone


0361-0128/98/000/000-00 $6.00 1540

0

5

10

15

20

25Joutel

0

5

10

15

20

25Matagami

0

5

10

15

20

25Quévillon

0

5

10

15

20

25

30Val-d'Or

0

5

10

15

20

25External North Volcanic Zone

5

10

15

20

25Hunter

0

5

10

15

20

25

0 25 50 75 100 125 150

Legend

FI

FII FIIIaFIIIb

Y

Zr/

YDunraine

Manitou-Barvue

Louvicourt

East-Sullivan

spherulitic rhyolite

Duvan

Lamorandière

Vendome

Abcourt

Hunter

LyndHurst

Langlois

Comtois

Eagle-Telbel

Poirier

Bell-AllardPerseverance

1

10

100Quévillon

1

10

100Val-d'Or

1

10

100

0 25 50 75 100 125 150

1

10

100Hunter

1

10

100Joutel

1

10

100Matagami

100

1

10

LegendFI

FII

FIIIa FIIIb

Langlois

Comtois

Eagle-Telbel

Poirier

Bell-Allard

Perseverance

Dunraine

Manitou-Barvue

Louvicourt

East-Sullivan

spherulitic rhyolite

Hunter

Lyndhurst

Duvan

Lamorandière

Vendome

Abcourt

[La/

Yb]

CN

YbCN

External North Volcanic Zone

FIG. 6. Binary classification diagrams of Zr/Y vs. Y (Lesher et al., 1986) and [La/Yb]CN vs. YbCN (Barrie et al., 1993), show-ing some overlapping of discrimination fields leading to uncertainty in rhyolite classification. Classification fields are fromLentz (1998) and chondrite-normalizing values (CN) from Nakamura (1974).


0361-0128/98/000/000-00 $6.00 1541

0

5

10

15

20

25Bousquet

0

5

10

15

20

25Gemini-Turgeon

5

10

15

20

25Selbaie

0

5

10

15

20

25Normétal

0

5

10

15

20

25

30Noranda

0

5

10

15

20

25

0 25 50 75 100 125 150

Other

0

5

10

15

20

25Chibougamau

Y

Zr/

Y

Géant Dormant

Coniagas

Lemoine

Normétal footwall

Superhyolite (silification)

Selbaie, zone A1

Laronde zone 20 footwall

Bouchard-Hébert (1100)Horne

Delbridge

Inmont

1

10

0 25 50 75 100 125 150

Other

1

10

100Noranda

1

10

100Bousquet

1

10

100Gemini-Turgeon

1

10

100Chibougamau

1

10

100Normétal

1

10

100Selbaie

100

Laronde zone 20 footwall

Selbaie, zone A1

Normétal footwall

Superhyolite (silification)

Lemoine

Géant Dormant

Coniagas

Bouchard-Hébert (1100)

Horne

Delbridge

Inmont

[La/

Yb]

CN

YbCN

FIG. 6. (Cont.)

FIIIa RhyolitesThe FIIIa rhyolites are also considered to be tholeiitic,

high-silica, high-temperature rhyolites, but they have slightlyfractionated REE patterns with [La/Yb]CN chondrite-normal-ized values ranging from 1.5 to 3.5, low Zr/Y ratios, moderateHFSE contents relative to the primitive mantle, variable neg-ative Eu anomalies, and weak, subduction-related negativeNb and Ta anomalies. This type of rhyolite was first describedin the Noranda mining district (Lesler et al. 1986). Similarrhyolites have been identified in association with VMS de-posits in the Joutel, Chibougamau, Normétal, and Quévillonmining districts.

Noranda

The Noranda mining district, located in the Blake RiverGroup of the Southern Volcanic zone, is well known for itsVMS deposits. More than 33 deposits totaling 135 Mt havebeen mined, including the world-class, gold-rich Horne mine(54 Mt). The 2706 to 2696 Ma (Pearson and Daigneault,2009) Blake River Group comprises almost half of the South-ern Volcanic zone, where it is considered to form a thick (upto 10–15 km) and laterally extensive stratovolcano covering anarea of about 3,000 km2 (e.g., Pearson and Daigneault, 2009).The volcanic stratigraphy consists of a bimodal sequence ofrhyolite and andesite flows (Dimroth et al., 1982). Five vol-canic cycles were defined near the synvolcanic Flavrian plu-ton (Gibson, 1990). Cycle 3 hosts a number of felsic units,some of which are separated by chert horizons that constitutethe locus for VMS deposits (Gibson and Watkinson, 1990).The Blake River Group differs from most other parts of theAbitibi belt by its exceptional state of preservation, with onlyweak deformation and subgreenschist facies metamorphism,and it has been the focus of numerous geochemical studies(e.g., Gélinas et al., 1984; Peloquin et al., 1996).

Twenty-two samples were collected across the Blake RiverGroup (Fig. 3). The strategy was to collect samples withinand around the footwall of VMS deposits and away fromknown VMS deposits, and to cover most accessible and ex-posed rhyolite horizons. Samples from the Bouchard-Hébertand Inmont mines are from the immediate footwall. Samples

from the Horne and Delbridge mines are from lateral exten-sions of the host rhyolite. Figure 8A shows that 20 of thesamples have the characteristics of FIIIa rhyolites. SampleR-92 has lower mantle-normalized element abundances buta similar HFSE-REE pattern (except for Ti), whereas REEfractionation is more pronounced in sample R-90. Samplesfrom the VMS deposits plot within the range of backgroundrhyolite compositions (shaded area in Fig. 8B), except sam-ples R-74 and R-82. Sample R-74 from the Horne mineshows weak to intermediate REE depletion. Intense hy-drothermal alteration, as indicated by strong sericitization inthin section (App. 2), likely explains the depletion of REE.MacLean and Hoy (1991) documented similar LREE mobil-ity caused by intense hydrothermal alteration of rhyolite atthe Horne mine. However, the lower abundances of themore immobile elements, such as Y and Yb, suggest an un-derlying more fractionated initial REE signature, a featurealso documented by MacLean and Hoy (1991) at the Hornemine. These findings are consistent with those of Peloquin etal. (1996).

Joutel

The Joutel volcanic complex is 5 to 7 km thick and consistsof bimodal basalt-rhyolite successions that formed during fiveepisodes of volcanism, which evolved from tholeiitic to tran-sitional to calc-alkaline (Legault et al., 2002). Phase 2 (2728 ±2 Ma: Mortensen et al., 1993) is a 2- to 3-km-thick sequencecomposed mostly of dacite and rhyolite flows hosting threeZn-Cu-Ag VMS deposits, the Poirier (7 Mt), Joutel Copper(1.7 Mt), and Explo-Zinc (1 Mt) deposits (Fig. 4A). A limitednumber of geochemical analyses were performed on rocksfrom the major VMS-hosting unit. Phase 5 is represented bya 100- to 300-m-thick and laterally extensive (20 km) tuffa-ceous felsic calc-alkaline unit that hosts the volcanogenicEagle-Telbel Au-Ag massive to semimassive sulfide deposit(Gauthier et al., 2003). These rocks are interpreted to be FItype (see below).

We collected samples from a rhyolite unit with U-Pb zirconages of 2728 Ma (Mortensen et al., 1993: sample R-47), nearknown VMS deposits, and at locations some distance from theVMS deposits (Fig. 4A). The felsic tuff hosting the Eagle-Tel-bel Au-Ag deposit was also sampled. Two types of rhyolites,FII and FIIIa, were found (Fig. 8C). The FIIIa rhyolites arespatially associated with the Poirier and Joutel VMS deposits,whereas FII rhyolites are located at the top (eastern part) ofthe Joutel volcanic complex.

Chibougamau (Lemoine)

The Chibougamau area is known for its epigenetic Cu-Ausulfide veins (Pilote et al., 1998), rather than VMS-type de-posits. One exception is the small (0.75 Mt) but very high-grade and gold-rich Cu-Zn-Au-Ag Lemoine deposit hosted bythe felsic Waconichi Formation (Guha et al., 1988). This 2730Ma (Mortensen et al., 1993) formation forms a thin, domi-nantly calc-alkaline belt that can be traced throughout theChibougamau area (Fig. 4B). It is mainly tuffaceous in na-ture, with lesser porphyritic intrusions (Daigneault and Al-lard, 1990). Near the now-closed Lemoine mine, the felsicrocks are tholeiitic (Gobeil, 1980) and have well-defined,lobed lava flow facies indicating a proximal effusive center.


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Three samples were collected around the Lemoine depositand three others from the Waconichi Formation away fromthe deposit (Fig. 4B). Samples from Lemoine have HFSE-REE patterns typical of FIIIa rhyolites (Fig. 8D). Onestrongly chloritized, silicified, and sericitized sample (R-113;App. 2) has lower LREE (La, Ce, Nd) contents presumablycaused by intense hydrothermal alteration (Campbell et al.,

1984; MacLean, 1988). Sample R-110 to the north has an FIIsignature, and samples R-109 and R-108, as previouslynoted, are FI tuffs (see sections on FI and FII rhyolitesbelow). The various signatures from the extensive WaconichiFormation suggest a volcanic evolution or an unrecognizedcomplexity including various volcanic vents of specific geo-chemical compositions.


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FIG. 8. Multielement plots normalized to primitive mantle (Sun and McDonough, 1989) for FIIIa felsic volcanic samplesfrom various districts. A. Noranda district: gray envelope includes samples R-67 to -71, R-73, R-75 to -81, R-83, R-84, R-88,R-89, R-93, R-95 to -97, and R-99 away from VMS. B. Noranda district: plots of rhyolite samples directly associated withVMS deposits. C. Joutel district: dashed-line samples are FII rhyolites. D. Chibougamau area: gray envelope includes sam-ples R-111 and R-112. E. Normétal district: dashed-line samples are FII rhyolites. F. Quévillon area: gray envelope includessamples R-4, R-8, and R-9.

Normétal

The 4-km-thick Normétal volcanic complex forms a south-east- to east-trending, steeply dipping, monoclinal volcanicsuccession that can be traced along strike for 35 km (Fig. 4C).It consists of basaltic andesite, dacite, and rhyolite eruptedduring five distinct volcanic phases with an intervening sedi-mentary phase (Lafrance et al., 2000; Mueller et al., 2008).Two VMS deposits were mined: the 11-Mt Cu-Zn-Au-AgNormétal deposit and the smaller (0.2-Mt) Zn-rich Normet-mar deposit. The associated volcanic center consists of amafic-dominated shield volcano of transitional affinity whichevolved to a felsic-dominated composite volcano with threeprincipal vent sites of tholeiitic affinity dated at 2728 Ma(Mortensen et al., 1993). The VMS deposits are associatedwith the last stage of tholeiitic felsic volcanism.

Samples were collected along the felsic horizon, 2.5 kmwest (sample R-36) and 14 km east (sample R-38) of the Nor-métal deposit, and from its immediate vicinity (samples R-35,R-36: Fig. 4C). Rhyolites spatially associated with VMS min-eralization are typically FIIIa (Fig. 8E), whereas samplesaway from the deposit have fractionated HFSE-REE patternswith characteristics comparable to FII-type rhyolites (see FIIsection).

Quévillon

The Quévillon area hosts the Zn-Cu-Ag Langlois mine(previously known as the Grevet mine) as well as other de-posits that are currently being explored (e.g., the Orpheezone) or developed (e.g., the 97 zone of Breakwater Re-sources Ltd). This area has past production and reserves to-taling more than 20 Mt of ore (Lacroix et al., 1993). TheGrevet-Mountain volcanic complex, dated at 2718 Ma (Daviset al., 2005), is bound to the north by a tonalitic intrusion andto the south by the synvolcanic Mountain pluton (Fig. 4D).The volcanic setting of the deposits is poorly understood be-cause the volcanic strata lie along a major southeast-trendingregional discontinuity known as the Cameron fault (Lacroix etal., 1993). The favorable, steeply dipping, 2-km-thick volcanicsequence has been traced along strike for more than 20 km(Fig. 4D). Around the Langlois mine, felsic rocks alternatewith mafic bands and are transposed by penetrative schistos-ity (Lacroix et al., 1993). Regionally, the Quévillon area con-sists of numerous southeast- to east-trending rhyolitic bands,some of which consist of lava flows and domes, and others oftuffaceous rocks (Fig. 4D). In addition to VMS mineraliza-tion, the Quévillon area hosts the Comtois gold deposit—anatypical, volcanogenic disseminated sulfide deposit (Dupré etal., 2002) associated with FI rhyolite (see below).

A rhyolite sample taken near the Langlois mine (Fig. 4D)has an FIIIa signature (sample R-4), and other FIIIa rhyoliteswere also found in the Quévillon area (samples R-8, R-9: Fig.8F). Sample R-6, collected near the mine, has a more frac-tionated REE pattern and lower amounts of mantle-normal-ized values (Fig. 8F). This sample may represent an in-terbedded tuffaceous horizon within the FIIIa host sequenceof the Langlois mine. The sample from the footwall of theLanglois mine (R-5) has lower mantle-normalized REEabundances relative to Ta, Zr, Hf, and Y. The high concen-tration of SiO2 (86 wt %) indicates strong silicification, which

is supported by the petrographic data (App. 2), and this likelyaccounts for the variability in REE concentrations. Othersamples (R-1, R-2, and R-3) represent FI rhyolites and arediscussed below.

FII RhyolitesThe FII rhyolites have calc-alkaline to transitional affini-

ties, gently sloping REE patterns indicated by [La/Yb]CN

chondrite-normalized values of 1.7 to 8.8, moderate Zr/Y ra-tios, intermediate HFSE concentrations, variable Eu anom-alies, and moderately negative Ta and Nb anomalies. They areinterpreted as arc-related rhyolites (Barrie et al., 1993; Hartet al., 2004). Rhyolites of the FII category host VMS depositsin the Val-d’Or and Selbaie mining districts, and make up theHunter volcanic complex and the largest portions of the ex-ternal North volcanic zone and Gemini-Turgeon areas.

Val-d’Or

The Val-d’Or mining district (Fig. 5A) may be best knownfor its gold deposits, but it is also a major VMS district withore production and reserves in excess of 60 Mt from six Cu-Zn-Ag-Au deposits (Jenkins and Brown, 1999). The VMS de-posits are hosted within the south-facing, steeply dipping, andlaterally extensive (40 km long) Val-d’Or Formation, measur-ing 3 to 5 km thick (Pilote et al., 1999; Scott et al., 2002). This2704 Ma formation comprises a complex subaqueous vol-cano-sedimentary sequence dominated by volcaniclastic de-posits ranging from andesitic to felsic compositions, overlyingthe synvolcanic granodioritic Bourlamaque pluton (Scott etal., 2002). The VMS deposits are spatially associated with nu-merous, small, felsic-dominated volcanic centers of limitedextent (Pilote et al., 1999). The volcanic rocks are mainly oftransitional affinity and are interpreted as the products of arcvolcanism (Scott et al., 2002). The 2701 Ma Heva Formationis 2 to 3 km thick, overlies the Val-d’Or Formation, and in-cludes a laterally extensive, spherulitic dacitic unit that hasbeen traced for 40 km along the base of the Heva Formation(Scott et al., 2002). The Heva Formation consists mainly oftholeiitic mafic rocks and is interpreted as a product of fis-sure-type volcanism (Scott et al., 2002). VMS deposits are notknown in the Heva Formation, with the possible exception ofthe Akasaba Au-Ag deposit (Chartrand, 1989; Vovobiev, 2000).

The lithogeochemistry of felsic volcanic rocks from the Val-d’Or Formation was studied in detail by Pilote et al. (1999)and Scott et al. (2002). They concluded, using mainly Zr/Y ra-tios, that felsic volcanism evolved from tholeiitic to calc-alka-line near the top of the Val-d’Or Formation, although mostunits are of transitional affinity.

We collected samples underground from the footwall at theLouvicourt mine and at surface along the host rhyolite hori-zons at the former East Sullivan, Manitou-Barvue, and Dun-raine mines (Fig. 5A). Samples were collected along a north-south transect within the Val-d’Or and Heva Formations andincluded the spherulitic dacitic unit and the eastern portionof the Sleepy volcanic center (Fig. 5A).

Multielement diagrams reveal that most rhyolite samplesform a coherent group with typical FII characteristics (Fig.9A). The spherulitic dacite sample (R-13) has an HFSE-REEpattern typical of FIIIa rhyolites (Fig. 9A). The low SiO2 con-tent (59.03%) suggests a more andesitic composition, but the


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FIG. 9. Multielement plot normalized to primitive mantle (Sun and McDonough, 1989) for FII felsic volcanic samplesfrom various districts. A. Val-d’Or district: gray envelope includes samples R-10 to R-12, R-15 to -18, R-20, and R-116 awayfrom VMS. B. Val-d’Or district: plots of rhyolite samples directly associated with VMS deposits. C. External North Volcaniczone area: gray envelope includes samples R-23, R-25, R-26, R-28 to -31, R-42, and R-43. D. Selbaie district. E. Hunter dis-trict: gray envelope includes samples R-55 to -66, excluding R-61 away from VMS. F. Hunter district: plots of rhyolite sam-ples directly associated with VMS deposits. G. Gemini-Turgeon area: gray envelope includes samples R-121 to -123. H.Other rhyolite samples with FII signatures.

unusual magnetite alteration observed in this sample (and inthe unit generally) may account for the higher Fe2O3 andlower SiO2 content of this dacitic rock (App. 1). The Sleepysample (R-19) is characterized by an unusual signature, withLa and Ce depletion relative to Zr and Hf, and lower HREE(Gd, Yb) and Y abundances compared to other samples. Thissignature may reflect hydrothermal alteration (La, Ce mobil-ity) of a more fractionated rhyolite (lower HREE and Y). Thepresence of biotite (App. 2) suggests a higher metamorphicgrade related to the proximity of the Grenville Province (Fig.1) and also may account for the anomalous signature.

The tuff sample from the Heva Formation (R-14), dated at2702 Ma (Pilote et al., 1999), has a HFSE-REE pattern sim-ilar to that of the rhyolite group, but with lower overall man-tle-normalized values (Fig. 9A). The low Al2O3 content andLOI (App. 1) suggest that the sample is silicified, whichwould explain the lower HFSE-REE abundances. Samplestaken near VMS deposits plot within the range of backgroundrhyolites (shaded field, Fig. 9B), except for the Louvicourtfootwall sample, which has the same REE-HFSE pattern buthigher mantle-normalized element abundances.

External North Volcanic zone

The external North Volcanic zone covers a large area ofabout 6,000 km2, spanning the towns of Lasarre, Amos, andSenneterre from east to west. It is bound by the linearChicobi sedimentary unit to the north and by the Porcupine-Destor-Manneville fault to the south (Fig. 5B). This largearea is dominated by mafic lavas with lesser bands of felsicvolcanic rocks and local synvolcanic plutons (Gaboury, 2006).Ages range from 2727 to 2714 Ma (Labbé, 1999), indicatingprolonged or multiphase volcanism. The large area is reputedto be a weakly favorable area for hosting VMS deposits. Ex-cept for the Abcourt deposit, only small VMS deposits havebeen discovered, including Jay Copper, Monpras, Trinity,Vendome 1 and 2, and Duvan (Fig. 5B). Although some de-posits were explored underground (Amos, Duvan, Vendome),only the Abcourt deposit has been mined, producing about 6Mt of ore grading 3 percent Zn and 40 g/t Ag (Labbé andCouture, 1999).

Fourteen samples of rhyolite were collected, four near theAbcourt, Duvan Vendome, and Lamorandière VMS deposits(Fig. 5B). Although the sampled area is large and containsrocks of various ages, the rhyolites define a coherent group ofFII type in Figure 9C. Two represent FI-type rhyolites (R-37at Duvan and R-32) and are discussed in the FI section below.

Selbaie mining district

The 2725 to 2730 Ma Brouillan Volcanic Complex (Barrieand Krogh, 1996) is mainly composed of felsic to intermedi-ate calc-alkaline pyroclastic rocks forming an intracaldera se-quence more than 1,200 m thick (Larsen and Hutchinson,1993). The caldera sequence, which developed above the syn-volcanic Brouillan tonalitic batholith, records an evolutionfrom subaqueous to subaerial deposition. The south-facingvolcanic sequence is tilted and may be traced laterally 12 kmwestward (Taner, 2000), but no significant deposit occursaway from the Selbaie mines. Selbaie is an atypical large-ton-nage, low-grade volcanogenic Cu-Zn-Ag-Au deposit withboth stratiform and epithermal characteristics that has

yielded more than 50 Mt of ore (Larsen and Hutchinson,1993). Mineralization occurs as veins and veinlets that cut thelocal stratigraphy at a high angle and as stratiform, massive todisseminated pyrite lenses of low metal content.

Barrie et al. (1993) concluded that rhyolitic rocks at Selbaiewere of Group III in their classification system, which isequivalent to FII. For this study, two samples were collectedfrom the open pit of the A1 mineralized zone and anotherfrom rhyolite 5 km west of the mine (Fig. 1). The multiele-ment diagram indicates that these are of FII type with mod-erately fractionated REE and well-defined Ta-Nb anomaliestypical of calc-alkaline rocks (Fig. 9D).

Hunter mine area

The 2728 to 2724 Ma Hunter mine group is a 6- to 7-km-thick volcanic sequence composed mainly of felsic lava flowsand domes with lesser volcaniclastic felsic rocks, iron forma-tions, and mafic pillowed and brecciated flows (Mueller andMortensen, 2002). This group forms a 210-km2 area of tilted,south-facing volcanic rocks overlying the synvolcanic, gran-odioritic Poularies intrusion (Fig. 4C). The main feature is aprominent north-trending felsic dike swarm, 5 to 7 km wide,interpreted as a caldera structure (Mueller and Donaldson,1992; Mueller et al., 2008). To date, only two small Cu-Zn-Ag-Au VMS deposits have been discovered, Hunter and Lyn-dhurst, totaling less than 2 Mt of ore (Fig. 4C).

We collected 12 samples east and west of the Poularies in-trusion (Fig. 4C). Included in this group are samples from theHunter (R-55) and Lyndhurst mines (R-62, R-63), both pastproducers. Another sample, R-57, is from the north-trendingfelsic dike swarm. With the exception of R-61, which has lowermantle-normalized element abundances (Fig. 9E), the sam-ples, including those from VMS deposits (Fig. 9F), define acoherent compositional group with a very restricted range ofREE-HFSE mantle-normalized abundances typical of FIIrhyolites. These results are consistent with those of Dostal andMueller (1996) and demonstrate the very restricted chemicalevolution of rhyolitic volcanism at the scale of the complex.

Gemini-Turgeon area

A felsic horizon with a thickness of about 2 km has beentraced for more than 15 km in a north-south direction to thewest of the synvolcanic Mistaouac pluton (Fig. 1). Rhyolitesin this area are unexposed and all known geology has been de-duced from drill core. The following description is from un-published data of the IAMGOLD and Cancor mining com-panies and from Gobeil (2006). The volcanic units consist ofa bimodal assemblage of porphyritic lava flows with few vesi-cles at the base, succeeded upward by predominantly felsicvolcaniclastic rocks and a sedimentary sequence comprised ofgraywacke, siltstone, mudstone, and iron formations. U-Pbdating of zircons from the top of the volcanic pile yielded anage of 2735 Ma (Davis et al., 2005). Numerous small, massive,and disseminated volcanogenic sulfide lenses, with low Cu,Zn, Au, and Ag grades, occur mainly along the top of the vol-canic sequence.

Four representative samples were provided by Cambior Inc.(now IAMGOLD) for this study. All samples are of FII-typerhyolite (Fig. 9G), although the [La/Yb]MN mantle-normal-ized values are among the highest of the FII-type rhyolites.


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One sample (R-120), however, has lower REE-HFSE man-tle-normalized abundances, probably caused by silicification(84.15 wt % SiO2).

Other FII occurrences

Figure 9H shows a multielement diagram for other felsicrocks with FII signatures. Sample R-106 is from the mined-out 0.7-Mt Coniagas Zn-Pb-Ag VMS deposit (Fig. 1). SampleR-119 is a felsic tuff dated at 2718 Ma (Pilote et al., 1999),collected near the Marbridge Ni-Cu komatiite-hosted deposit(Fig. 1). Sample R-85 is from the 2718 Ma (Zhang et al.,1993) Kinojevis Formation (Fig. 5).

FI RhyolitesThe FI rhyolites are calc-alkaline, with strongly fraction-

ated REE patterns, [La/Yb]CN chondrite-normalized valuesranging from 5.8 to 34, low HFSE abundances, strong nega-tive Ta and Nb anomalies, and variable Eu anomalies. Theyare interpreted as arc-related magmatic products (Barrie etal., 1993). These rhyolites occur in the Bousquet mining dis-trict and are spatially associated with other gold-rich vol-canogenic deposits, namely the Géant Dormant (SleepingGiant), Eagle-Telbel, and Comtois deposits, and the atypicalDuvan Cu-Ag deposit.

Bousquet mining district

The Bousquet mining district is a world-class gold producerthat includes Laronde—the world’s largest polymetallic gold-rich VMS deposit (Mercier-Langevin et al., 2007a)—andpyritic gold-bearing replacement-type deposits such as Bous-quet 1 and Dumagami-Bousquet 2 (Fig. 1). Total productionand reserves amount to more than 100 Mt of ore. Recent re-gional studies have traced the 1.5- to 3-km-thick, south-fac-ing, vertically tilted, strongly foliated, and east-trending vol-canic Bousquet Formation for more than 20 km along strike(Lafrance et al., 2003). This 2696 to 2698 Ma Formation,which is part of the Blake River Group, consists of volumi-nous dacitic to rhyolitic vesicular volcaniclastic rocks withlocal felsic effusive lava flows and domes to which the VMSdeposits are spatially associated (Lafrance et al., 2003). Thissequence overlies the Mooshla synvolcanic tonalite-granodi-orite pluton that hosts two synvolcanic, sulfide-rich vein-typegold deposits, Doyon and Mouska, both active producers.The Bousquet Formation is divided into lower and upper vol-canic members. The lower member includes tholeiitic totransitional, mafic to felsic volcanic rocks, whereas the uppermember is dominated by transitional to calc-alkaline, inter-mediate to felsic rocks (Lafrance et al., 2003; Mercier-Langevin et al., 2007a).

Sampling of the upper member was performed along anorth-south section along Preissac Road, using the unitnomenclature of Lafrance et al. (2003). One sample (R-105)from the underground Laronde mine rhyolite (unit 5.3, whichhosts the 20-N zone) was kindly provided by P. Mercier-Langevin (then of Agnico-Eagle) for this study. Overall, thesamples display strong REE fractionation, the Laronde foot-wall sample having the strongest, and very pronounced nega-tive Ta and Nb anomalies typical of FI rhyolites (Fig. 10A).

An exhaustive lithogeochemical study on the Laronde minewas recently conducted by Mercier-Langevin et al. (2007b).

These authors interpreted some of the dacites and rhyolites ofthe upper member as belonging to the FI category, althoughthey are dominated by FII-type rhyolites.

Other mineralized systems associated with FI rhyolites

Figure 10B shows a plot of mineralized felsic rocks with FIsignatures from other locations, such as the Géant Dormantmine in the internal North Volcanic zone (Fig. 1), the Agnico-Telbel mine in the Joutel district (Fig. 4A), and the ComtoisAu deposit in the Quévillon area (Fig. 4D). Mineralizationstyles range from sulfide-rich quartz veins (Géant Dormant:Gaboury and Daigneault, 1999) to sulfide disseminations inzones of highly altered rocks (Agnico-Telbel: Gauthier et al.,2003; Comtois: Dupré et al., 2002). All these deposits arehosted, at least in part, by felsic dikes and rhyolitic lavas of FIaffinity (Géant Dormant, Comtois) or within FI-type felsictuffs (Agnico-Telbel). The Cu-Ag Duvan mine is another ex-ample of atypical volcanogenic-related mineralization withinFI felsic tuff. Mineralization occurs as concordant massive todisseminated pyrite and chalcopyrite associated with abun-dant magnetite (Tremblay et al., 1996).

Other FI occurrences

Numerous occurrences of tuffaceous rhyolite scatteredacross the Abitibi belt have FI signatures (Fig. 10C). Theycommonly occur as extensive regional units. Samples R-108and R-109 are from the 2730 Ma (Mortensen et al., 1993)Waconichi Formation in the Chibougamau area (Fig. 4B),sample R-30 is from the Quévillon area (Fig. 4D), and twoother samples (R-32, R-41) are from the North Volcanic zone(Fig. 5B). These units may be products of explosive eruptionof felsic calc-alkaline magma with a high volatile content (e.g.,Gibson et al., 1999). Other rhyolites from the Comtois (R-1)and Géant Dormant (R-115) deposits and the rhyolite (R-107) dated at 2791 Ma (Bandayera et al., 2004) are plotted inFigure 10D. The 2791 Ma rhyolite is unusually old relative tothe 2735 to 2700 Ma ages for felsic volcanism in the Abitibibelt.

DiscussionThe results of this study reveal that in small volcanic cen-

ters composed of various rhyolite types, such as Joutel, Chi-bougamau (Lemoine), Normétal, and Quévillon (Fig. 8),VMS deposits are specifically associated with FIIIa rhyolites.This demonstrates the usefulness of the approach for dis-criminating the most favorable sectors or horizons withinsmall felsic volcanic centers. The much larger Noranda dis-trict is also characterized by rhyolites with FIIIa signatures,but the application of rhyolite chemistry in the exploration ofthis camp is less useful because FIIIa rhyolites are distributedover such a vast area (more than 3,000 km2).

Regardless of rhyolite classification, there does not appearto be any link between ore tonnage and REE fractionation.VMS deposits are hosted by rhyolites with REE patternsranging from low [La/Yb]MN mantle-normalized ratios or flatpatterns (Matagami) to elevated [La/Yb]MN ratios or fraction-ated patterns (Bousquet-Laronde; Fig. 11). Furthermore,moderately fractionated FII rhyolites (Selbaie, Hunter, Val-d’Or, and External North Volcanic zone) are variably mineral-ized, as was previously recognized by Lesher et al. (1986).


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0.1

1

10

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Roc

k /

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itive

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tle

FI-mineralizedR-105 Laronde

R-46Agnico-Telbel

R-2 Comtois

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R-37 Duvan

B

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FIG. 10. Multielement plots normalized to primitive mantle (Sun and McDonough, 1989) for FI felsic volcanic samples.A. Samples from the Bousquet district. Gray envelope includes samples R-100 to -104. B. Mineralized samples from variouslocations. C. Samples from tuffaceous rhyolite at various locations. D. Other rhyolite samples with FI signatures.

Bousquet: > 100 Mt

n=7

Val-d'Or: 60 Mt

n=13

Hunter: 2 Mt

n=14

Noranda: 132 Mt

n=24

External North Volcanic Zone : 10 Mt

n=15

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1000Matagami: 50 Mt

n=4

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ThTaU

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n=3

Quévillon: 20 Mt

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ThTaU

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Zr TiSmEu YbGd

Y ThTaU

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FIG. 11. Summary multielement plots normalized to primitive mantle (Sun and McDonough, 1989) for felsic volcanicrocks from mining districts, showing ore tonnages (production and reserve) in millions of metric tons (Mt).

Based on our dataset, it is not possible to attribute a greaterVMS potential to specific rhyolite types based only on geo-chemical signatures.

Rhyolite petrogenesis and hydrothermal activity

The formation of VMS deposits is the product of convectivehydrothermal activity induced by heat flux from an underly-ing magma chamber (Franklin et al., 1981, 2005). Funda-mental factors that enable hydrothermal convection to occurinclude the structural permeability of the upper portion ofthe crust and the porosity of the volcanic pile (e.g., Mortonand Franklin, 1987; Barrie and Hannington, 1999; Gibson etal., 1999; Davidson et al., 2004). Time is another key factorthat is fundamental in maintaining the stability of the convec-tive system and in accumulating sulfides on or near the seafloor (e.g., Barrie and Hannington, 1999; Franklin et al.,2005, and references therein).

Rhyolites are the result of petrogenetic processes involvingpartial melting, crystallization, fractionation, and assimilation(e.g., Hart et al., 2004). The depths at which these processesoccur, the magma ascent rates, and the residence times in thecrust also influence rhyolite chemistry. The same factors in-fluence hydrothermal convection and VMS formation (e.g., interms of thermal requirements). However, this study illus-trates that different types of rhyolites are not necessarily morefavorable than others to host VMS deposits. This may be be-cause VMS formation is mainly related to processes thatoccur at shallow levels in the crust (<5 km: see Franklin et al.,2005) rather than at great depth (<30 km: see Hart et al.,2004) where the rhyolite magma is generated.

High-temperature FIII-type rhyolites (e.g., Noranda andKidd Creek) have low amounts of phenocrysts and microphe-nocrysts (Hart et al., 2004). This generally aphyric texture isthought to reflect a rift setting where magma is rapidly trans-ferred from the melt zone to the surface (Lentz, 1998; Hartet al., 2004) and quartz and feldspar do not accumulate insubvolcanic magma chambers. However, our data suggestthat most VMS districts in this study, except Normétal andVal-d’Or, are dominated by quartz- and/or feldspar-phyric fel-sic lava flows or volcaniclastic rocks. The apparent inconsis-tency between phenocryst content, rhyolite type, and VMSfavorability is difficult to explain with a model that involves agenetic link between deep petrogenetic processes for rhyolitegeneration and VMS formation. The most likely explanationis the presence of subvolcanic magma chambers above zonesof magma generation, which would account for phenocrystformation. Such subvolcanic intrusions are well documentedfor most VMS districts in the Abitibi belt (Galley, 2003;Gaboury, 2006).

Fractionation pattern and style of volcanism

The FIII rhyolites are well known as volatile-poor rocks oc-curring in bimodal, basalt-rhyolite sequences (Lentz, 1998).These sequences, as exemplified by the Noranda andMatagami districts, are dominated by isolated to coalescentvolcanic centers forming domes (e.g., cycle 3 of Noranda) andextensive flows (e.g., Watson Group of Matagami) with rarevolcaniclastic horizons mainly of epiclastic origin (Table 1).Extensive cherty horizons or silicified tuffs indicating periodsof volcanic quiescence are also typical of these sequences.

The FI rhyolites, which are at the other end of the frac-tionation spectrum, are poorly represented in the Abitibi belt.Volcanic rocks in the Bousquet district form a continuouscompositional range from andesite to rhyodacite in volcani-clastic-dominated sequences (Table 1). Vesicularity is intenseand quiescent periods (cherty horizons) have not yet beenidentified (Lafrance et al., 2003; Mercier-Langevin et al.,2007a). Other known FI rhyolites in the Superior province,such as at Obonga Lake (Tomlinson et al., 2002), in theMichipicoten belt (Sage et al., 1996), Meen-Dempster(Hollings et al., 2000), and in the North Caribou terrane(Hollings and Kerrich, 1999), are also dominantly tuffaceousbut are not mineralized.

The FII rhyolites, characterized by a moderate fractiona-tion pattern, are variably dominated by either volcaniclastic orcoherent flow facies. The Val-d’Or and Selbaie districts arecharacterized by a continuous volcanic compositional rangefrom andesite to rhyolite with large volumes of highly vesicu-lar volcaniclastic rocks (Table 1). On the other hand, theHunter district and the volcanic centers of the External NorthVolcanic zone are dominated by flow and lava domes of lowvesicularity and bimodal composition (Table 1).

Fractionation pattern and style of mineralization

The VMS deposits associated with FIII rhyolites are typical“Noranda-type” deposits forming high-grade but relativelylow-tonnage deposits (1–4 Mt), with the largest examplesbeing Mattagami Lake (25.6 Mt) and Quémont (13.8 Mt). Amajor exception to this trend is the giant 240-Mt Kidd CreekVMS deposit in Ontario, which is also genetically related toFIIIb rhyolites (Lesher et al., 1986).

The gold-rich Horne deposit, the largest VMS in the No-randa district, features replacement-style mineralization instrongly sericitized felsic volcaniclastic rocks (Table 2). Someof the host rhyolites are FII type with calc-alkaline affinity, aspreviously documented by MacLean and Hoy (1991). Thepresence of more than one rhyolite type may be explained bythe fact that the Horne mine is part of a different block thanthe felsic rocks of the central Noranda district (Kerr and Gib-son, 1993). The Horne block is interpreted as a parallel riftenvironment to the central cauldron (Kerr and Gibson, 1993)or the top of the proposed New Senator caldera (Pearson andDaigneault, 2009).

Deposits associated with FI rhyolites are commonly atypi-cal Cu-Au–rich deposits, ranging in style from sulfide-richquartz veins to disseminations to sulfide replacements of per-meable rocks (Table 2). Striking examples are the VMS de-posits in the Bousquet area. Mineralization occurs mainly asmassive sulfide replacements within highly permeable andhighly vesicular volcaniclastic rocks. Well-defined Cu-richstringer zones in the chlorite-altered feeder pipes of strati-form lenses are absent in many cases (Table 2). Aluminous al-teration in the Cu-Au deposits at Dumagami, Bousquet 1 and2, and Laronde (zone 20) has been compared to high-sulfida-tion alteration in epithermal Cu-Au deposits (Sillitoe et al.,1996; Hannington et al., 1999b; Dubé et al., 2007).

Mineralization associated with FII rhyolites is quite vari-able (Table 2). In the Selbaie area, mineralization occurs ascopper-rich stringers and zinc-rich disseminations with poorlydeveloped stratiform mineralization (Table 2). In the Val-d’Or


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district, VMS deposits form large accumulations of dissemi-nated sulfides with low Cu and Zn grades replacing perme-able volcaniclastic horizons (except for the Louvicourt de-posit) and lack well-defined underlying chloritic and Cu-richzones (Table 2). In the Hunter district, mineralization hostedby FII rhyolite is more similar to that associated with FIIIrhyolite, in that small massive sulfide lenses of exhalative ori-gin accumulated at the top of the volcanic sequence alongwith banded iron formations during the waning stage of sub-marine volcanic activity (Table 2). Well-developed discordantsulfide stringers and chlorite alteration zones are also associ-ated with these deposits (Table 2).

Summary and ConclusionsRhyolites cover a complete spectrum of geochemical frac-

tionation patterns that can be conveniently subdivided intoinformal FI-FII-FIII types. Furthermore, there is a completespectrum of VMS deposits in terms of volcanic facies associa-tions, base metal and gold contents, and alteration character-istics (Table 3). It emerges that there are no objectively bar-ren rhyolite types, and that beyond any petrogeneticconsiderations involving the depth of felsic magma genera-tion, other factors must be taken into account to explain thefull spectrum of variations between geochemical signaturesand volcanogenic hydrothermal activity.

Possible factors are temperature, viscosity, and volatile con-tent, all of which have a profound influence on the volcanicproducts and consequently on the volcanic architecture(Touret, 1999). Submarine volcanic architecture in turn re-flects the growth history, topography, effusive rate, bathyme-try, and possible eruptive interference from other proximalvolcanic centers (Cas, 1992; Gibson et al., 1999).

The favorability of FIII rhyolites is commonly explained bythe rapid transfer of low-volatile magma to the surface, thusinducing high heat flow (cf. Lentz, 1998). The extensional set-ting, manifested by well-defined calderas, rifts, or grabens fa-vors magma ascent and provides enhanced structural perme-ability for the convective hydrothermal system (e.g., Hart etal., 2004). The bimodal sequences, with multicycle volcanismand hiatuses in volcanic activity, provide enough time to ac-cumulate significant quantities of sulfides on the sea floor,mainly by exhalative processes, with VMS deposits formingnear-volcanic rhyolite lava flow centers and domes (Gibson etal., 1999).

The VMS deposits associated with FI rhyolites are com-monly replacements of highly permeable volcaniclastic rocks.These rocks are the main products of explosive eruption ofcalc-alkaline magma with a high volatile content. In suchcases of replacement-style mineralization, a hiatus in volcanicactivity is not necessary to form a VMS deposit by sea-floorexhalation, and these sequences commonly lack evidence oflong pauses in volcanic activity. In addition to forming abun-dant volcaniclastic rocks, the explosive volcanism may pro-mote enhanced structural permeability and contribute tolarge variations in bathymetry and confining pressure. De-posits typically occur close to isolated volcanic vents, as ex-emplified by the Bousquet district (Lafrance et al, 2003) andthe Géant Dormant gold deposit (Gaboury and Daigneault,1999). The high gold content of many of these deposits hasbeen interpreted as a consequence of a magmatic gold con-tribution (Hannington et al., 1999b, 2005; Gaboury et al.,2000; Mercier-Langevin et al., 2007b). It is well known thatmagmas similar in composition to FI-type rhyolites emplacedin a subaerial setting are favorable hosts for Cu-Au porphyrydeposits (Reich et al., 2003; Mungall, 2004).

It is noteworthy that FII sequences represent about 70 per-cent of rhyolites by surface area in the Abitibi (Pearson,2005). For these moderately fractionated rhyolites, the traceelement approach has some limitations when assessing rela-tive prospectivity. Mineralized FII rhyolites, such as those ofVal-d’Or, Selbaie, and Bousquet, have volcanic facies andmineralizing characteristics that are more similar to FI se-quences, whereas those of the Hunter, Gemini-Turgeon, andExternal North Volcanic zone districts share characteristicswith the FIIIa sequences, such as those of Noranda (Tables 3,4). The FII sequences appear to be the most favorable hostsfor VMS deposits when the volcanic style is dominated byhighly vesicular volcaniclastic rocks derived by continuousfractionation from andesite to rhyolite. Conversely, thosesharing characteristics of the FIII rhyolites—such as lowvesicularity and bimodal dome- and lava flow-dominated se-quences in the Hunter, External North Volcanic zone andGemini-Turgeon districts—host “Noranda-type” deposits butappear less prospective.

The FI rhyolites appear highly favorable for VMS depositsbut host styles of mineralization that differ from the classicstrata-bound VMS lenses, including gold-bearing, sulfide-richquartz veins, disseminations, and replacement-type sulfidelenses. A similar conclusion was reached by Mercier-Langevin et al. (2007b) based on their study of felsic rocks atthe Laronde mine. Some FII rhyolites have a high potentialto host VMS, such as Val-d’Or and Selbaie, whereas others,


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TABLE 3. Style of Volcanism and Mineralization Associated with Different Rhyolite Types

Group Volcanism style Mineralization style

FIII Bimodal Exhalative stratiform lensesLow volatile content High grade, low tonnageDomes and flows Cu-Zn ± Ag ± AuLow vesicularity index Discrete alteration pipe and Few volcaniclastic rocks Cu-rich stringer zoneExhalite-chert: common Examples: Quémont

Mattagami LakeAnsil

FII Similar to FIII-type Similar to “FIII-type”Examples: Lyndhurst

Hunter mineGemini

Similar to FI-type Similar to “FI-type”Examples: Selbaie

Manitou-Barvue

FI Continuum andesite to rhyolite Atypical Cu-AuAbundance of volcaniclastic veins, disseminations and

rocks replacement of permeable High vesicularity volcaniclastic rocksExhalite-chert: absent Diffuse alteration

Examples: Laronde Bousquet 1 and 2Comtois

such as in the Hunter, External North Volcanic zone, andGemini-Turgeon districts, appear only weakly mineralized.The FII sequences host either Noranda-type VMS associatedwith flow-dome complexes or disseminated sulfide replace-ments and veins in dominantly volcaniclastic rocks. Volcani-clastic rocks appear to be the most favorable host for large-tonnage deposits and provide an important guide forexploration. The dominance of highly prospective FIII rhyo-lites in very large felsic centers, such as Noranda andMatagami, is a less useful exploration guide at the target scale.However, in small felsic centers that show an evolution fromFIIIa to FII to FI, deposits are directly associated with FIIIarhyolites, and their presence is thus a much more useful toolfor targeting horizons with the greatest potential.

AcknowledgmentsG. Bouchard of Xstrata Zinc (previously Noranda-Falcon-

bridge) was instrumental to this study by suggesting it andproviding technical support. P-L. Lajoie of the Universitédu Québec à Chicoutimi (UQAC) provided dedicated fieldassistance during the 2003 sampling program and samplepreparations. J. Lavoie (UQAC) performed the petrographicstudy. This project benefited from numerous comments byrepresentatives on the CONSOREM Research Committee.We also acknowledge CONSOREM for permission to pub-lish this work. T. Gomwe of UQAC and V. Bodycomb of VeeGeoservices edited the English, and R. Daigneault ofUQAC informally reviewed a preliminary version of themanuscript. The paper was substantially improved followingreviews by T. Hart and P. Hollings. We are also grateful toM. Hannington for his constructive comments and efficienteditorial work.

November 14, 2006; September 2, 2008

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8939

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3778

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9630

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342

5327

748

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932

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946

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960

Ta

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0.66

0.84

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232

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166

1.53

91.

212

0.16

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801

2.01

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620.

81.

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2.64

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503

0.72

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844.

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543.

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945

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836

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571

1.74

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276

0.30

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572

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693

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244

0.80

80.

513

0.90

10.

870.

416

0.41

60.

707

0.50

70.

951.

323

Y 7.

898.

265.

0159

.18

51.9

45.

2410

9.31

54.7

419

.87

25.5

535

.610

1.48

17.4

919

.89

26.1

131

.31

33.1

4Yb

0.

930.

920.

496.

116.

180.

5312

.06

6.15

2.56

3.04

3.77

11.6

1.83

2.04

3.01

3.63

3.49

Zr

154.

314

377

.130

1.3

308.

598

.147

5.1

402.

112

6.5

262.

230

2.4

318

130.

723

2.2

188

290.

523

0.2

Be

0.

70.

560.

60.

741.

290.

921.

820.

880.

330.

920.

830.

550.

251.

130.

390.

921.

2C

o 2.

072.

635.

940.

431.

612.

265.

310.

164.

581.

25.

1510

.34

9.06

14.9

18.

345.

422.

13C

u

47.3

26.

9623

.56

6.64

27.8

23

9.11

23.0

768

.87

6.1

103.

519

.52

13.6

63.

4273

.02

3.59

23.9

3L

i 53

2614

13

213

44

37

252

4318

88

Ni

10.3

74.

7615

.58

6.02

7.6

9.17

5.34

2.9

4.19

4.71

7.46

13.4

545

.59

41.3

38.

398.

872.

41Sc

2.

81.

95.

42.

11.

12.

76.

72.

97.

18.

512

.118

.214

.59.

612

.513

.222

.2V

9.

065.

2458

.94

1.95

2.14

25.9

420

.92.

051.

435

.44

133.

761

.08

118.

9388

.77

56.6

849

.44

113.

41Zn

43

.77

10.0

551

.12

83.7

713

610

.34

72.5

439

.11

62.7

68.

5441

.36

58.4

846

.45

192

69.8

11.9

916

.91

Ba

36

8.24

698.

2329

7.04

115.

1640

2.28

425.

8430

9.43

312.

3134

6.45

227.

231

8.3

145.

93.

6832

813

6.1

145.

4837

3.75

Cd

0.

054

0.05

20.

035

0.10

80.

113

0.03

10.

122

0.09

90.

046

0.12

40.

072

0.09

50.

046

0.08

0.05

80.

054

0.05

3C

r

4637

.41

62.4

734

.97

30.4

627

.22

13.7

211

.94

12.6

411

.92

24.3

660

.248

.28

86.9

522

.51

22.0

59.

78G

a 18

.64

16.3

917

.79.

8515

.82

19.4

927

.03

19.4

710

.91

24.1

17.0

420

.61

10.2

617

.78

14.0

114

.58

15.1

8M

o

55

3.14

3.17

3.16

1.79

1.39

0.85

3.08

0.74

1.06

0.5

1.95

0.22

0.35

0.88

1.09

Pb

3.8

2.5

3.8

6.1

11.7

2.6

2.3

2.4

22.5

27.9

3.6

1.8

1.4

6.5

1.8

1.4

5.8

Sn

0.9

11.

122.

514.

061.

065.

445.

343.

312.

542.

42.

160.

871.

981.

811.

692.

02T

l 0.

210.

220.

170.

081.

920.

280.

090.

070.

630.

030.

150.

010.

10.

050.

030.

27W

0.

730.

480.

180.

210.

421.

80.

80.

860.

540.

50.

790.

480.

720.

690.

560.

181.

07


0361-0128/98/000/000-00 $6.00 1555

Num

ber

R-1

9R

-20

R-2

1R

-22

R-2

3R

-25

R-2

6R

-27

R-2

8R

-29

R-3

0R

-31

R-3

2R

-34

R-3

5R

-36

R-3

7

Zone

1818

1818

1717

1718

1717

1717

1717

1717

17U

TM

E32

3164

3116

0130

3148

3024

8071

8033

7164

1571

6415

2960

2771

1276

7013

5970

0608

6844

2268

1858

6194

0161

8604

6172

3761

5340

UT

MN

5326

912

5330

063

5367

105

5377

870

5381

228

5387

455

5387

447

5399

513

5388

917

5393

938

5388

487

5389

578

5394

610

5429

078

5429

499

5430

259

5416

389

SiO

2(w

t %)

75.4

169

.33

81.7

669

.52

55.1

377

.61

70.6

574

.72

54.5

965

.860

.24

62.1

162

.88

83.6

488

.82

75.3

964

.65

Al 2O

312

.21

14.2

46.

8712

.33

16.3

612

.44

13.5

512

.56

16.1

915

.57

15.6

413

.98

17.1

610

.99

9.74

13.5

617

.5Ti

O2

0.66

0.6

0.11

0.37

0.7

0.2

0.32

0.17

0.86

0.79

0.54

0.76

0.25

0.16

0.05

0.56

0.35

Fe 2

O3

5.96

4.56

5.56

3.49

8.31

0.23

4.38

2.8

9.15

2.84

7.14

5.59

1.85

0.97

0.02

2.96

3.96

MgO

1.

874.

150.

220.

895.

620.

680.

714.

930.

953.

943.

10.

980.

541.

322.

24M

nO

0.12

0.03

0.11

0.13

0.03

0.05

0.15

0.08

0.11

0.07

0.02

0.01

0.06

0.09

K2O

1.

392.

942.

22.

171.

611.

952.

361.

220.

722.

651.

321.

754.

142.

180.

533.

011.

82C

aO

0.15

0.44

0.02

3.62

5.79

1.23

2.41

0.7

8.71

5.6

7.56

4.54

3.77

0.03

0.03

0.18

2.68

Na 2

O

0.43

0.1

1.14

2.72

4.05

2.05

5.41

1.86

4.58

2.27

2.43

4.25

0.77

0.05

0.24

4.87

P 2O

50.

120.

30.

010.

120.

140.

030.

070.

030.

140.

180.

110.

140.

080.

020.

020.

110.

12L

OI

2.

393.

383.

726.

142.

91.

723.

541.

083.

390.

632.

095.

984.

481.

660.

422.

221.

98To

tal

100.

1910

0.4

100.

5899

.91

99.4

99.4

510

0.04

99.4

510

0.7

99.6

510

0.96

100.

4599

.86

100.

9899

.65

99.6

210

0.26

Ce

(pp

m)

7.23

29.7

422

.36

54.4

233

.959

.44

73.9

111

6.95

27.2

853

.228

.61

34.5

17.9

419

.88

18.1

932

.51

35.9

8C

s

0.92

10.

918

0.51

31.

533

1.64

50.

952

2.53

0.93

60.

905

0.13

40.

645

1.29

22.

364

1.71

0.08

61.

036

3.11

5D

y

1.08

2.50

24.

629

6.04

83.

773

6.34

97.

867

13.7

883.

625.

977

2.99

43.

584

0.73

74.

668.

796

6.93

0.92

1E

r

0.83

11.

671

3.91

53.

963

2.24

33.

436

4.93

28.

121

2.22

83.

642

1.8

2.19

60.

334

3.03

76.

193

4.30

20.

408

Eu

0.

228

0.80

70.

666

1.75

71.

071.

073

1.37

71.

428

1.12

61.

527

0.76

10.

975

0.49

60.

452

0.27

30.

481

0.73

7G

d

1.22

63.

668

3.75

96.

535

3.93

36.

867

7.79

614

.022

3.72

55.

863

3.06

33.

798

1.23

93.

583

6.34

15.

589

1.70

2H

f 3.

35.

46.

66.

64.

16.

17.

18.

33.

36.

63.

44.

92.

34.

84

7.3

2.7

Ho

0.

249

0.51

21.

123

1.28

40.

772

1.22

21.

633

2.76

50.

756

1.24

10.

609

0.74

80.

127

0.99

91.

979

1.44

70.

156

La

2.

6610

.76

9.63

22.8

214

.64

27.8

534

.05

53.0

911

.95

24.9

212

.97

15.4

58.

447.

316.

7813

.13

16.7

4L

u

0.17

40.

352

0.78

70.

650.

335

0.49

50.

766

1.25

0.32

40.

543

0.26

60.

316

0.04

20.

487

0.96

60.

618

0.05

2N

b

48.

312

.911

.27.

210

.913

.623

.96

10.7

5.9

8.1

2.2

1015

.312

.12.

6N

d

5.63

17.7

12.9

631

.42

17.3

228

.834

.35

58.7

114

.72

25.4

613

.83

178.

788.

412

.37

15.9

716

.92

Pr

1.12

73.

881

2.96

17.

289

4.29

67.

175

8.75

914

.652

3.51

36.

369

3.43

94.

195

2.21

52.

117

2.64

84.

114.

467

Rb

23.1

658

.06

39.0

248

.21

58.7

641

.33

45.8

641

.41

19.1

548

.539

.28

48.3

475

.57

68.9

46.

9741

.84

47.8

8Sm

1.

414.

223.

237.

253.

826.

77.

6813

.47

3.35

5.58

2.98

3.71

1.7

2.34

4.46

4.46

2.71

Sr

242.

249

.815

.122

625

5.6

70.6

78.9

5420

8.1

133.

115

9.5

115.

321

3.5

42.9

137

.141

7.4

Ta

0.33

0.55

0.96

0.81

0.6

1.14

1.33

1.99

0.48

0.91

0.53

0.66

0.22

0.86

1.43

0.9

0.22

Tb

0.

177

0.47

0.66

10.

974

0.62

31.

087

1.27

72.

279

0.60

20.

974

0.50

30.

603

0.15

50.

709

1.28

31.

091

0.19

9T

h 1.

031.

521.

353.

21.

485.

997.

828.

671.

313.

831.

812.

371.

392.

915.

632.

862.

7T

m

0.13

80.

270.

664

0.61

30.

336

0.50

20.

749

1.22

30.

321

0.54

0.26

20.

319

0.04

60.

465

0.96

30.

631

0.05

5U

0.

380.

666

0.65

40.

932

0.50

81.

170.

739

2.13

60.

341.

046

0.47

60.

750.

491

0.98

20.

504

0.89

20.

898

Y 6.

6913

.73

31.7

735

.06

21.3

829

.61

45.8

372

.29

20.6

234

.39

17.0

420

.46

3.47

28.5

56.4

38.9

24.

24Yb

1.

022.

034.

844.

232.

223.

315.

018.

342.

113.

541.

732.

060.

33.

136.

374.

10.

36Zr

12

1.5

204.

721

5.4

251.

916

4.5

205.

724

0.6

247.

313

2.5

257.

513

8.6

199

87.9

159

79.4

294.

310

3.8

Be

0.

471.

30.

20.

810.

630.

940.

791.

140.

490.

610.

540.

711.

050.

960.

11

0.94

Co

9.46

4.6

5.13

2.75

35.9

41.

12.

821.

7331

.06

6.81

29.5

120

.88

5.86

0.9

21.

1610

.41

Cu

26

048.

249.

4114

.87

51.4

32.

2712

.48

20.4

641

.56

40.7

358

.69

41.4

83.

845.

071.

182.

744

.71

Li

1424

88

221

5215

192

1024

1115

211

48N

i 14

.09

3.57

7.55

4.91

183.

834.

234.

963.

7986

.38

7.38

77.3

794

.94

20.5

12.

091.

596.

2221

.57

Sc

11.3

101.

57.

215

3.4

7.3

418

.510

.614

.611

.63.

31.

61.

25.

25.

1V

10

2.21

11.5

94.

269.

0313

9.78

2.67

21.8

73.

9215

0.88

6692

.59

111.

4941

.27

3.32

49.1

152

.35

Zn

69.0

963

.66

1232

485

.66

8.36

76.3

777

.38

96.8

859

.373

.63

65.7

625

.16

32.6

13.

5858

.03

70.2

1B

a

299.

3613

8.4

263.

8849

2.65

259.

6233

9.31

384.

0615

7.88

278.

8963

5.19

260.

1729

3.61

549.

4126

3.98

5.46

696.

8738

9.46

Cd

0.

037

0.04

30.

049

0.3

0.08

40.

050.

050.

073

0.10

10.

125

0.06

60.

072

0.04

90.

035

0.06

10.

082

Cr

61

.19

11.7

616

.46

12.7

325

1.62

12.5

515

.02

11.9

114.

1414

.95

74.2

126.

0718

.86

9.43

9.82

11.4

830

.57

Ga

17.1

813

.14

11.0

118

.58

19.3

115

.95

19.2

118

.45

18.2

418

.66

15.2

917

.86

20.1

416

.48

15.0

923

.16

19.8

Mo

2.

680.

532.

171.

850.

840.

480.

620.

591.

151.

52.

120.

640.

40.

650.

291.

381.

42Pb

2.

93.

212

.838

.25.

22.

13.

98.

46.

314

.12.

24.

45.

26.

61.

640

7.2

Sn

1.2

1.77

3.07

2.65

8.24

3.55

3.9

9.59

1.66

3.48

2.67

1.77

2.44

3.54

5.39

100.

81T

l 0.

540.

10.

960.

140.

120.

160.

090.

090.

140.

140.

180.

430.

140.

020.

290.

23W

0.

560.

250.

660.

550.

580.

421

0.68

0.22

0.66

0.18

0.34

0.57

0.79

0.81

3.79

0.29

APP

EN

DIX

1(C

ont.)


0361-0128/98/000/000-00 $6.00 1556

Num

ber

R-3

8R

-41

R-4

2R

-43

R-4

4R

-45

R-4

6R

-47

R-4

8R

-50

R-5

1R

-52

R-5

3R

-54

R-5

5R

-56

R-5

7

Zone

1717

1717

1717

1717

1717

1818

1818

1717

17U

TM

E63

3686

6566

7567

0257

6858

2269

5000

6950

1869

1184

6928

1969

0587

6429

7830

5709

2995

1530

5403

3114

7963

7049

6342

1162

0877

UT

MN

5424

766

5419

254

5405

392

5409

034

5479

820

5479

815

5485

776

5482

091

5479

711

5520

033

5507

623

5514

904

5512

540

5516

571

5379

247

5378

698

5388

093

SiO

2(w

t %)

76.1

464

.02

61.0

682

.32

68.8

772

.39

62.6

879

.73

70.6

267

.35

73.3

978

.48

65.8

865

.19

71.1

570

.22

73.0

1A

l 2O3

13.9

718

.25

14.8

69.

8912

.32

13.4

516

.15

11.6

12.2

13.0

911

.41

9.61

10.5

912

.65

10.9

413

.43

12.7

3Ti

O2

0.36

0.32

0.81

0.12

0.45

0.53

0.52

0.09

0.41

0.49

0.3

0.26

0.64

0.89

0.31

0.6

0.28

Fe 2

O3

0.27

3.21

71.

585.

163.

176.

361.

525.

163.

765.

84.

3712

.62

10.3

36.

732.

053.

9M

gO

0.27

2.15

4.57

0.07

3.27

0.44

1.92

0.2

2.59

1.02

1.1

2.26

6.34

1.57

2.12

0.21

1M

nO

0.04

0.11

0.03

0.07

0.06

0.12

0.04

0.09

0.08

0.07

0.05

0.05

0.1

0.14

0.08

0.06

K2O

8.

321.

671.

751.

941.

551.

840.

752.

151.

964

3.48

0.75

0.05

0.55

2.43

1.21

1.61

CaO

4.

275.

180.

210.

940.

733.

250.

551.

193.

170.

870.

090.

133.

330.

082.

961.

87N

a 2O

0.

124.

54.

283.

312.

334.

225.

882.

062.

291.

362.

242.

624.

460.

175.

413.

74P 2

O5

0.03

0.09

0.17

0.02

0.08

0.11

0.1

0.02

0.07

0.15

0.05

0.03

0.12

0.2

0.07

0.15

0.06

LO

I

1.18

1.66

1.18

0.91

5.45

2.85

2.6

2.13

2.91

5.53

1.79

1.78

4.11

1.19

6.64

3.13

2.83

Tota

l 10

0.66

100.

1810

0.96

100.

4110

0.48

99.7

810

0.34

100.

1199

.599

.99

100.

5110

0.3

100.

5310

0.46

100.

7899

.46

101.

08

Ce

(pp

m)

47.5

620

.06

34.7

150

.124

.32

33.0

626

.29

61.5

947

.336

.72

91.7

389

.41

42.1

366

.84

30.1

140

.01

64.2

2C

s

1.44

62.

022

1.44

60.

484

0.98

81.

565

0.24

40.

469

0.34

31.

061.

360.

119

0.03

20.

127

0.33

60.

958

0.44

8D

y

3.54

10.

696

3.56

413

.305

2.64

33.

288

1.64

27.

256

9.09

94.

417

2020

16.5

2916

.961

1.74

12.

723

4.42

4E

r

2.04

10.

316

2.08

38.

892

1.71

31.

983

0.90

64.

851

5.99

12.

833

18.2

1313

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11.0

6711

.104

1.03

61.

567

2.68

6E

u

1.07

80.

634

1.11

11.

134

0.56

80.

798

0.76

50.

654

1.73

10.

938

3.34

43.

097

2.05

42.

625

0.35

31.

084

1.21

2G

d

4.24

71.

159

3.80

710

.257

2.56

43.

388

2.12

56.

291

8.16

84.

248

2018

.172

13.2

4315

2.10

33.

326

5.04

7H

f 7.

22.

83.

710

5.8

4.8

3.2

6.6

7.6

4.5

17.7

15.5

10.2

124.

44

6.4

Ho

0.

677

0.12

20.

719

2.94

0.56

60.

660.

323

1.57

91.

949

0.94

5.81

74.

464

3.59

63.

606

0.34

80.

535

0.89

8L

a

21.0

611

.14

15.6

821

.62

10.8

514

.98

12.6

226

.39

20.4

316

.53

35.5

434

.47

16.2

25.1

113

.85

17.7

29.4

9L

u

0.34

10.

041

0.29

51.

327

0.26

70.

305

0.13

0.72

30.

903

0.42

42.

791.

926

1.64

31.

678

0.16

10.

230.

409

Nb

11

.81.

77.

523

.18.

36.

13.

89.

110

.98.

428

.224

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.920

.35.

45.

99.

8N

d

22.8

58.

9618

.11

28.4

513

.316

.66

12.5

230

.18

28.4

118

.69

63.7

261

.97

31.5

45.8

414

.120

.329

.68

Pr

5.76

72.

396

4.41

76.

569

3.13

64.

123.

186

7.64

86.

447

4.53

913

.472

12.9

996.

399.

835

3.63

35.

057

7.70

8R

b 93

.469

.11

42.6

154

.36

25.8

740

.615

.44

40.2

334

.89

79.5

279

.04

13.2

0.72

6.41

33.6

31.7

435

.5Sm

4.

851.

583.

927.

692.

93.

542.

476.

457.

034.

117

.54

16.0

39.

3512

.56

2.58

3.95

5.94

Sr

21.3

602.

413

8.5

3249

.472

.913

829

.232

.743

.949

.124

.52.

758

.320

.493

.360

.8Ta

0.

990.

260.

621.

660.

720.

610.

430.

880.

850.

771.

821.

641.

121.

450.

590.

590.

87T

b

0.63

90.

145

0.59

51.

962

0.42

80.

536

0.29

71.

107

1.40

50.

698

3.88

63.

161

2.46

72.

633

0.29

70.

480.

759

Th

3.85

1.44

1.44

4.84

1.9

2.34

1.96

3.89

2.2

2.63

4.06

3.09

1.93

3.32

3.31

2.99

4.56

Tm

0.

317

0.04

40.

303

1.33

30.

263

0.29

80.

134

0.72

60.

894

0.42

42.

779

2.04

51.

641

1.65

10.

155

0.22

90.

406

U

0.87

30.

427

0.36

31.

290.

612

0.41

10.

463

0.97

50.

606

0.62

41.

035

0.83

70.

533

0.87

60.

902

0.62

90.

979

Y 16

.82

3.32

19.7

979

.81

14.7

617

.37

8.84

44.9

552

.92

25.9

812

011

5.18

95.3

596

.46

9.5

13.5

24.7

Yb

2.2

0.28

1.96

8.74

1.73

20.

874.

845.

912.

818

.26

13.3

110

.78

11.0

11.

061.

522.

69Zr

27

4.6

113.

715

5.4

332.

621

6.7

183.

112

720

2.6

288.

617

8.6

688.

856

5.8

375.

646

0.4

167

157.

325

7.2

Be

0.

580.

560.

460.

880.

560.

330.

430.

590.

810.

431.

781.

11.

010.

430.

310.

58C

o 0.

785.

6624

.83

0.25

9.06

4.53

16.7

60.

417.

747.

080.

910.

289.

8913

.29.

21.

623.

2C

u

2.67

4.53

40.2

318

.12

8.01

14.9

87.

1812

.35

29.1

56.

365.

8610

.06

30.1

412

.26

49.0

12.

51.

96L

i 9

2821

240

526

711

39

712

102

610

Ni

2.88

15.6

811

0.12

1.33

11.2

44.

0649

.75

1.32

8.16

2.8

2.36

1.22

1.29

2.88

4.81

1.7

2.1

Sc

3.3

3.8

15.1

2.1

2.7

6.2

10.2

3.2

7.9

7.1

2.3

0.8

12.1

12.8

3.3

6.5

5.6

V

6.79

42.2

114.

463.

4845

.27

31.6

992

.62

2.17

24.0

922

.73

5.23

1.78

3.71

40.7

17.7

430

.34

6.77

Zn

6.9

60.0

577

.24

88.7

473

.53

83.8

935

.28

72.4

611

4.99

54.0

613

6.05

217

84.0

285

.36

92.4

613

.51

55.2

7B

a

713.

9424

9.18

242.

6349

6.58

69.3

711

01.2

720

4.97

223.

0530

6.06

266.

7254

3.24

45.0

225

.85

140.

8643

3.61

273.

721

2.71

Cd

0.

050.

036

0.07

0.11

90.

066

0.05

70.

044

0.11

40.

063

0.06

20.

204

0.14

50.

075

0.09

70.

084

0.03

10.

062

Cr

10

.44

31.0

784

.66

8.71

15.5

48.

7564

.721

.33

10.1

8.12

8.45

9.08

8.18

8.26

Ga

19.3

423

.43

15.7

212

.75

17.9

416

.65

17.6

816

.09

20.7

517

.17

32.2

319

.84

28.4

623

.33

14.1

615

.72

15.0

7M

o

0.7

2.62

0.83

3.25

1.12

0.54

0.32

0.93

1.39

0.35

1.77

1.09

50.

811.

060.

370.

22Pb

2.

65

1.6

5.4

412

.11.

211

.43.

92.

24.

73.

80.

81.

38.

32

2.5

Sn

3.49

0.7

1.58

4.31

2.46

1.41

1.71

2.63

2.66

2.09

105.

683.

582.

081.

751.

312.

09T

l 0.

241.

040.

080.

080.

120.

250.

080.

130.

140.

121.

180.

160.

020.

160.

090.

12W

0.

450.

420.

180.

930.

270.

270.

320.

270.

251.

770.

720.

370.

710.

230.

680.

290.

23

APP

EN

DIX

1(C

ont.)


0361-0128/98/000/000-00 $6.00 1557

Num

ber

R-5

8R

-59

R-6

0R

-61

R-6

2R

-63

R-6

4R

-65

R-6

6R

-67

R-6

8R

-69

R-7

0R

-71

R-7

3R

-74

R-7

5

Zone

1717

1717

1717

1717

1717

1717

1717

1717

17U

TM

E61

5919

6171

4562

2270

6222

7365

0653

6504

4765

2983

6573

4365

4526

6341

7763

1020

6303

1862

7893

6260

0062

4067

6465

7364

7630

UT

MN

5387

853

5386

548

5383

127

5383

134

5382

153

5381

949

5383

580

5392

084

5391

921

5342

561

5341

497

5342

283

5342

497

5349

906

5351

508

5346

168

5347

494

SiO

2(w

t %)

75.9

72.2

866

.74

63.7

770

.29

79.6

375

.72

71.4

370

.89

67.3

570

.29

78.5

883

.18

81.8

872

.92

70.8

872

.83

Al 2O

39.

2712

.09

15.4

413

.81

7.62

10.1

312

.19

12.8

511

.13

10.2

314

.42

10.7

19.

1811

.34

12.6

13.2

611

.55

TiO

20.

250.

290.

50.

580.

130.

130.

280.

330.

220.

330.

330.

340.

20.

430.

260.

380.

26F

e 2O

36.

992.

693.

875.

4613

.49

3.84

3.62

3.14

9.76

5.91

5.22

2.17

0.96

0.51

4.88

6.2

7.12

MgO

0.

810.

341.

793.

264.

082.

641.

310.

591.

880.

750.

610.

250.

240.

450.

830.

281.

01M

nO

0.18

0.08

0.06

0.07

0.14

0.01

0.04

0.05

0.09

0.19

0.09

0.03

0.01

0.13

0.03

0.22

K2O

0.

80.

870.

661.

280.

241.

950.

840.

360.

91.

053.

10.

390.

083.

321.

223.

530.

22C

aO

1.72

2.82

1.22

4.21

0.02

0.02

0.13

20.

715.

961.

290.

910.

320.

190.

970.

071.

05N

a 2O

2.

015.

637.

824.

380.

224.

526.

652.

453.

13.

65.

615.

170.

524.

980.

624.

32P 2

O5

0.04

0.06

0.09

0.1

0.02

0.02

0.05

0.07

0.05

0.07

0.05

0.06

0.03

0.05

0.04

0.08

0.04

LO

I

2.76

2.9

1.57

2.94

5.08

2.4

1.47

2.15

2.05

5.6

1.24

0.36

0.4

1.57

1.04

4.14

1.93

Tota

l 10

0.74

100.

0699

.78

99.8

810

1.13

100.

9810

0.16

99.6

310

0.13

100.

5310

0.25

99.4

199

.76

100.

2699

.87

99.4

610

0.53

Ce

(pp

m)

47.0

962

.39

47.4

520

.81

47.6

743

.47

47.8

448

.86

33.4

933

.67

48.8

56.9

539

.26

29.9

354

.58

8.6

74.6

7C

s

0.14

50.

268

0.09

70.

424

0.06

20.

331

0.13

70.

173

0.27

90.

484

2.96

10.

134

0.09

11.

083

0.24

60.

754

0.16

4D

y

3.92

94.

744.

008

1.71

73.

785

3.88

23.

482

4.04

82.

007

5.79

38.

957

6.58

5.79

13.3

0810

.992

3.06

9.44

3E

r

2.38

2.76

72.

338

0.97

12.

171

2.39

52.

059

2.35

11.

229

3.68

46.

078

4.50

34.

061

10.0

487.

454

2.29

45.

935

Eu

1.

465

1.06

1.08

70.

618

0.46

20.

546

1.04

50.

924

0.47

91.

291.

687

1.14

50.

708

0.69

91.

550.

478

2.28

Gd

4.

025

5.08

14.

373

1.94

14.

125

3.93

3.82

93.

953

2.24

5.32

27.

875.

948

4.69

28.

822

9.26

41.

773

9.47

2H

f 4.

96

5.8

2.4

3.9

5.3

5.1

5.1

4.6

4.5

7.5

6.4

5.5

8.9

8.2

4.2

6.6

Ho

0.

806

0.95

70.

805

0.33

50.

761

0.78

90.

703

0.82

40.

411.

226

1.95

21.

437

1.28

53.

079

2.38

40.

717

1.95

6L

a

21.1

828

.81

19.8

79.

9522

.79

19.7

622

.55

22.3

414

.91

14.4

121

.22

29.6

216

.35

10.6

722

3.53

34.9

3L

u

0.35

10.

407

0.35

30.

139

0.29

40.

381

0.30

80.

351

0.20

70.

579

0.97

0.70

40.

666

1.60

11.

158

0.39

20.

951

Nb

8.

79.

78

3.6

4.5

86.

87.

26

7.9

12.6

11.1

9.8

14.9

13.5

8.8

16.8

Nd

22

.52

28.5

422

.88

9.92

22.0

220

.25

22.7

522

.34

14.6

319

.26

28.8

226

2122

.58

32.4

94.

6738

.21

Pr

5.71

17.

456

5.77

22.

526

5.59

95.

256

5.81

75.

848

3.87

64.

412

6.59

36.

642

5.14

54.

764

7.36

91.

122

9.29

7R

b 13

.23

22.5

17.

6422

.38

4.16

31.9

515

.67.

9418

.43

25.5

664

.97

8.05

1.58

56.2

825

.18

56.8

5.09

Sm

4.43

5.64

4.8

2.07

4.48

4.28

4.4

4.44

2.73

4.8

7.22

5.81

4.82

6.82

8.25

1.26

8.93

Sr

38.1

81.7

97.5

136.

84.

87.

639

.910

4.4

46.3

126.

816

9.5

79.9

57.3

18.8

82.7

13.9

31.6

Ta

0.75

0.88

0.77

0.44

0.56

0.78

0.76

0.69

0.64

0.63

0.93

0.89

0.79

1.05

0.99

0.69

1.14

Tb

0.

640.

798

0.67

40.

290.

629

0.62

60.

588

0.65

60.

338

0.90

61.

391.

030.

841

1.83

71.

638

0.39

61.

515

Th

3.22

4.4

4.02

1.42

2.95

4.12

3.16

3.47

3.26

1.71

3.21

3.43

3.2

2.11

2.75

1.9

2.78

Tm

0.

352

0.40

70.

350.

140.

312

0.36

20.

302

0.35

10.

194

0.55

40.

925

0.67

70.

636

1.59

71.

140.

372

0.89

4U

0.

781.

066

0.98

70.

357

0.75

30.

985

0.78

50.

851

0.83

90.

432

0.83

60.

877

0.83

80.

590.

744

0.57

70.

715

Y 22

.07

26.8

822

.73

9.11

20.4

21.3

818

.86

22.6

710

.933

.24

52.4

540

.13

34.5

281

.72

62.8

19.1

953

.92

Yb

2.28

2.69

2.31

0.92

2.01

2.45

2.01

2.27

1.34

3.74

6.26

4.51

4.24

10.6

67.

522.

56.

06Zr

19

7.9

230.

123

4.5

9615

2.4

200.

920

119

7.3

181.

218

0.2

283.

924

9.4

212.

930

6.8

310.

516

9.9

248.

7B

e

0.4

0.62

0.53

0.5

0.28

0.3

0.27

0.44

0.38

0.79

0.42

0.24

0.15

0.68

0.22

0.52

Co

5.21

2.45

8.15

19.1

15.3

66.

333.

073.

8210

.15

2.5

2.35

2.11

0.78

0.71

3.85

6.01

0.53

Cu

17

.81

3.39

27.3

237

.66

38.3

21.

782.

755.

2527

.09

5.02

109.

9238

.59

225

13.7

871

.83

104.

9920

.59

Li

93

712

1511

135

97

175

34

53

20N

i 0.

942.

1912

.28

57.0

13.

351.

31.

343.

195.

061.

331.

271.

430.

961.

843.

142.

151.

21Sc

5.

24.

87.

911

.13.

84.

26

52.

211

.913

.88.

44.

17.

613

.17.

410

.8V

3.

2110

.75

50.1

511

6.42

6.13

1.48

2.48

10.9

811

.39

4.16

5.13

4.41

1.6

1.81

1.5

15.4

61.

8Zn

81

.06

44.9

848

.67

64.9

126.

8125

.64

32.6

139

.04

55.0

863

.29

85.7

731

.62

28.0

618

.36

78.7

550

0022

5B

a

134.

0217

5.54

188.

6142

0.12

39.8

229

9.83

180.

7685

.86

201.

7217

9.61

872.

2416

4.31

35.9

144

1.29

482.

8934

0.36

47.8

3C

d

0.05

90.

047

0.10

60.

036

0.06

50.

041

0.04

40.

036

0.06

20.

041

0.10

70.

050.

037

0.08

40.

071

0.3

0.14

1C

r

8.64

16.1

492

.27

8.12

8.12

9.06

10.1

48.

078.

398.

9111

.34

9.08

Ga

12.0

415

.46

16.7

15.3

612

.05

14.2

914

.73

13.0

916

.07

13.8

220

.46

11.2

99.

267.

9818

.61

15.3

422

.01

Mo

2.

370.

310.

930.

642.

80.

720.

660.

31

0.87

0.37

0.36

0.71

0.94

1.69

0.98

3.38

Pb

3.3

3.3

3.3

13.1

1.3

1.4

1.9

1.5

4.9

1.3

3.5

4.5

1.3

31.

39.

43.

2Sn

1.

092.

262.

11.

340.

922.

171.

771.

321.

771.

152.

577.

91.

580.

932.

732.

563.

51T

l 0.

040.

070.

050.

140.

020.

210.

060.

040.

060.

080.

290.

050.

680.

080.

520.

04W

0.

260.

30.

250.

240.

580.

520.

220.

380.

210.

380.

420.

290.

410.

730.

30.

441.

88

APP

EN

DIX

1(C

ont.)


0361-0128/98/000/000-00 $6.00 1558

Num

ber

R-7

6R

-77

R-7

8R

-79

R-8

0R

-81

R-8

3R

-84

R-8

5R

-88

R-8

9R

-90

R-9

2R

-93

R-9

5R

-96

R-9

7

Zone

1717

1717

1717

1717

1717

1717

1717

1717

17U

TM

E64

6889

6510

0165

2251

6496

0964

5584

6480

3365

5360

6509

9165

2434

6693

1066

2609

6543

5564

2730

6412

0762

9641

6236

0762

0443

UT

MN

5347

743

5347

863

5350

159

5347

769

5350

329

5344

213

5361

370

5366

108

5371

275

5358

894

5358

869

5358

411

5351

864

5357

028

5360

526

5358

232

5365

459

SiO

2(w

t %)

72.9

574

.28

70.4

972

.79

70.9

573

.92

76.0

561

.94

73.9

664

.15

76.4

277

.455

.75

73.2

572

.65

74.8

873

.59

Al 2O

311

.33

11.5

610

.36

10.7

212

.55

9.61

10.9

217

.16

13.2

515

.06

10.1

611

.26

16.3

312

.46

12.2

611

.56

12.5

4Ti

O2

0.25

0.33

0.28

0.23

0.45

0.21

0.2

0.84

0.22

0.56

0.3

0.25

1.03

0.25

0.26

0.23

0.31

Fe 2

O3

5.43

2.08

3.99

5.23

4.71

1.69

2.18

6.23

2.92

4.71

3.21

1.49

9.03

4.35

3.95

3.5

4.4

MgO

0.

850.

572.

42.

191.

240.

10.

333.

170.

82.

791.

140.

094.

761.

180.

570.

180.

86M

nO

0.08

0.03

0.13

0.27

0.08

0.13

0.03

0.08

0.02

0.08

0.05

0.04

0.13

0.06

0.06

0.1

0.07

K2O

0.

291.

091.

22.

731.

510.

330.

631.

514.

782.

21.

533

1.13

2.1

0.61

4.07

1.36

CaO

1.

262.

673.

080.

922.

014.

621.

342.

60.

684.

252.

530.

556.

371.

61.

533.

041.

1N

a 2O

4.

984.

422.

91.

123.

975.

035.

743.

881.

273.

62.

294.

645.

093.

615.

381.

674.

56P 2

O5

0.04

0.06

0.07

0.04

0.08

0.04

0.05

0.13

0.03

0.16

0.07

0.05

0.14

0.03

0.05

0.04

0.07

LO

I

1.66

2.9

5.49

3.95

2.93

3.59

1.9

2.69

2.37

1.7

2.55

0.4

1.62

1.51

1.88

0.71

1.23

Tota

l 99

.12

100

100.

410

0.18

100.

4899

.27

99.3

810

0.23

100.

399

.27

100.

2499

.17

101.

410

0.39

99.1

999

.97

100.

09

Ce

(pp

m)

54.4

734

.09

55.4

546

.98

41.6

747

.96

56.8

732

.93

80.2

255

.88

59.2

796

.91

23.3

157

.15

40.8

655

.77

62.0

8C

s

0.12

60.

720.

652

1.40

50.

336

0.3

0.34

41.

239

2.35

11.

621.

234

0.32

20.

199

0.62

10.

163

0.33

10.

263

Dy

9.

573

5.29

77.

018

7.70

76.

233

8.24

76.

454.

561

7.76

42.

513

7.69

11.0

532.

808

10.8

438.

584

9.91

213

.25

Er

6.

328

3.51

34.

986

5.15

14.

152

4.69

44.

316

2.93

15.

052

1.32

85.

388

7.34

61.

626

7.11

25.

803

6.67

78.

979

Eu

1.

964

0.85

71.

274

1.70

71.

141

1.97

81.

241.

191.

298

1.35

21.

155

1.16

80.

953

1.89

21.

306

1.80

11.

885

Gd

8.

526

4.71

87.

315

7.19

85.

814

7.62

6.14

74.

309

7.92

63.

679

6.76

110

.046

3.01

99.

387

6.90

98.

823

11.8

46H

f 6.

55.

56.

76.

36.

94.

67.

34

9.3

3.3

6.8

8.1

2.7

8.4

6.8

7.9

7.5

Ho

2.

054

1.13

91.

504

1.68

21.

342

1.66

91.

392

0.96

51.

642

0.47

51.

684

2.36

80.

565

2.31

1.88

82.

151

2.86

8L

a

23.2

915

.94

22.5

19.8

217

.73

20.4

326

.19

14.0

835

.67

26.8

126

.89

46.2

10.1

124

.33

16.6

922

.96

25.9

4L

u

0.98

50.

551

0.91

60.

820.

693

0.58

0.72

10.

446

0.81

70.

185

0.88

61.

161

0.23

1.10

90.

885

1.07

1.42

2N

b

1510

.115

.314

.512

.210

.711

.48.

116

.54.

412

.717

.74.

814

.711

.613

.614

Nd

31

.49

17.7

32.5

27.7

523

.83

28.6

628

.25

18.4

541

.03

27.7

130

.13

46.2

512

.81

33.2

823

.95

33.1

39.6

2Pr

7.

264

4.23

7.50

46.

313

5.54

86.

481

7.02

74.

3310

.242

7.01

57.

319

11.7

132.

998

7.63

95.

483

7.55

78.

62R

b 6.

5232

.78

23.2

538

.522

.68

8.06

8.61

26.4

611

0.9

64.8

136

.49

38.1

20.2

848

.97

15.1

476

.924

.44

Sm

7.95

4.32

7.94

6.86

5.56

6.92

6.06

4.18

8.44

4.98

6.57

9.72

2.86

8.1

5.79

810

.32

Sr

68.2

46.1

58.2

24.6

55.8

36.1

53.2

149.

120

.674

1.2

38.1

24.6

185.

811

3.1

56.4

108.

576

.3Ta

1.

050.

771.

181.

020.

960.

770.

890.

641.

380.

430.

981.

290.

451.

020.

860.

981.

01T

b

1.48

10.

821

1.15

1.22

30.

978

1.30

91.

021

0.71

11.

253

0.47

21.

158

1.73

60.

471.

673

1.27

91.

522.

076

Th

2.66

3.13

3.97

2.64

3.85

1.95

3.51

2.11

6.5

3.51

5.08

5.8

1.22

3.12

2.5

2.81

3.28

Tm

0.

966

0.54

70.

799

0.79

40.

644

0.65

30.

680.

445

0.77

0.18

60.

856

1.15

10.

236

1.07

90.

879

1.03

11.

398

U

0.69

10.

875

1.00

40.

686

1.02

0.43

40.

845

0.55

41.

525

1.02

81.

213

1.28

90.

314

0.83

60.

696

0.71

70.

846

Y 55

.77

30.6

141

.39

40.6

735

.45

44.7

638

25.3

844

.09

12.9

345

.71

63.3

914

.962

.65

51.0

256

.71

74.4

6Yb

6.

423.

635.

675.

34.

364.

054.

532.

925.

151.

225.

787.

71.

527.

135.

726.

99.

28Zr

24

9.4

217.

322

3.2

232.

326

6.7

168.

230

1.6

155.

735

1.6

127.

424

7.2

272.

810

832

3.9

258

298.

724

8.6

Be

0.

410.

240.

550.

60.

470.

30.

180.

561.

220.

820.

540.

440.

390.

890.

640.

610.

66C

o 2.

162.

73.

880.

285.

060.

672.

3623

.04

2.89

20.5

93.

020.

8631

.38

1.18

1.69

0.77

2.07

Cu

24

710

.04

3.6

2.54

8.27

9.42

8.64

21.2

447

.32

44.7

23.6

521

.43

79.9

3.9

9.2

2.95

3.33

Li

179

910

113

2313

4211

25

87

26

Ni

1.28

1.98

2.35

1.22

2.28

1.4

1.95

52.2

26.

9290

.08

2.08

1.82

48.7

21.

111.

131.

541.

26Sc

10

5.9

5.3

8.1

9.9

6.6

5.9

15.5

810

.56.

85.

419

.310

.910

.610

.410

.9V

1.

7611

.16

15.7

2.94

16.1

2.73

2.97

158.

3415

.39

94.2

910

.72

9.11

224.

452.

72.

632.

674.

74Zn

58

.65

19.1

75.0

812

0.59

61.2

517

.43

303

67.4

849

.24

71.8

846

.78

27.4

312

5.33

55.6

332

.36

26.0

771

.46

Ba

73

.47

114.

8827

1.09

578.

2928

9.55

38.1

148.

4737

1.41

381.

193

6.66

315.

9750

2.76

262.

5887

298

.83

673.

1731

5.08

Cd

0.

155

0.06

60.

090.

054

0.05

30.

056

0.28

10.

040.

090.

075

0.07

40.

058

0.09

50.

074

0.04

80.

059

0.06

Cr

10

.21

8.12

60.9

412

.315

4.66

8.02

66.8

8G

a 16

.94

13.4

614

.51

18.1

15.9

8.18

9.84

19.7

520

.36

17.2

12.3

614

.16

19.1

920

.72

17.3

523

.38

19.2

3M

o

1.67

0.28

0.84

1.29

0.59

0.49

1.17

0.57

4.96

1.13

0.58

0.84

0.32

0.8

0.97

0.4

0.32

Pb

3.4

1.5

1.6

3.2

1.3

2.7

401.

72.

29.

15

2.2

9.5

2.2

0.8

3.9

2Sn

1.

21.

421.

141.

261.

41.

164.

51.

093.

281.

093.

414.

81.

61.

522.

42.

793.

52T

l 0.

030.

160.

090.

080.

040.

020.

590.

110.

470.

460.

120.

170.

140.

190.

060.

140.

09W

0.

380.

180.

220.

540.

260.

230.

270.

193.

20.

340.

180.

290.

140.

260.

690.

210.

24

APP

EN

DIX

1(C

ont.)


0361-0128/98/000/000-00 $6.00 1559

Num

ber

R-9

9R

-100

R-1

01R

-102

R-1

03R

-104

R-1

05R

-106

R-1

07R

-108

R-1

09R

-110

R-1

11R

-112

R-1

13R

-114

R-1

15

Zone

1717

1717

1717

1718

1818

1818

1818

1818

18U

TM

E64

7642

6826

9169

0128

6901

2069

0141

6901

3169

1000

4153

3648

5960

5316

8653

4514

5328

4756

5339

5653

2256

3604

2832

0228

3202

UT

MN

5358

250

5347

877

5347

240

5347

192

5347

379

5347

279

5347

500

5483

070

5431

392

5495

949

5499

618

5524

237

5513

155

5513

845

5512

701

5446

802

5446

202

SiO

2(w

t %)

80.5

270

.41

69.9

372

.06

66.4

672

.45

76.9

263

.43

76.5

962

.62

74.4

277

.15

69.3

273

.08

74.6

668

.774

.4A

l 2O3

9.15

13.1

215

.88

14.0

314

.98

11.6

512

.03

11.5

213

.29

15.7

513

.83

10.2

912

.712

.42

10.8

714

.35

10.8

2Ti

O2

0.12

0.36

0.25

0.32

0.62

0.22

0.17

0.35

0.1

0.57

0.06

0.19

0.39

0.45

0.16

0.36

0.22

Fe 2

O3

1.8

3.85

2.32

1.87

3.94

1.5

0.95

9.19

0.5

5.71

0.48

3.53

4.16

4.56

7.83

3.45

1.37

MgO

0.

540.

411.

160.

581.

710.

830.

431.

440.

013.

550.

350.

470.

230.

972.

090.

870.

42M

nO

0.04

0.09

0.06

0.06

0.11

0.07

0.03

0.37

0.09

0.02

0.05

0.09

0.05

0.03

0.07

0.03

K2O

2.

044.

024.

372.

911.

741.

453.

091.

021.

251.

443.

012.

222.

430.

721.

794.

432.

1C

aO

1.41

2.58

1.51

2.87

4.68

4.23

1.75

11.6

40.

394.

611.

321.

923.

481.

342.

353.

95N

a 2O

1.

990.

221.

812.

551.

913.

631.

981.

075.

833.

873.

941.

033.

065.

180.

240.

332.

15P 2

O5

0.03

0.05

0.04

0.08

0.15

0.06

0.04

0.08

0.06

0.12

0.03

0.03

0.06

0.09

0.02

0.1

0.08

LO

I

2.11

3.5

2.29

2.19

3.42

3.4

2.51

0.77

0.68

2.22

2.11

3.18

3.91

1.34

2.56

4.06

3.82

Tota

l 99

.76

98.6

99.6

399

.53

99.7

399

.48

99.9

100.

8898

.71

100.

5599

.56

100.

0499

.84

100.

2110

0.24

99.0

699

.36

Ce

(pp

m)

68.1

411

7.46

89.6

892

.37

81.4

349

.54

72.7

853

.77

32.6

335

.51

19.9

168

.75

93.7

313

4.56

5.38

42.0

738

.34

Cs

1.

539

0.53

66.

636

2.81

52.

713

1.61

52.

875

0.19

60.

567

0.93

70.

917

0.94

10.

218

0.12

30.

202

2.69

91.

336

Dy

10

.377

7.79

13.

228

3.66

44.

174

2.46

22.

143

5.98

91.

515

2.36

91.

177

8.92

315

.543

2020

1.46

13.

091

Er

7.

238

4.70

12.

213

2.31

2.75

31.

799

1.49

63.

987

1.03

71.

428

0.74

66.

078

10.5

2813

.548

19.7

090.

766

2.34

Eu

1.

274

1.92

30.

837

1.30

71.

472

0.48

40.

687

1.38

70.

334

0.79

90.

317

1.08

61.

912.

518

1.13

70.

604

0.96

2G

d

9.25

67.

994

3.40

74.

281

4.83

82.

482.

433

6.43

1.25

12.

715

1.25

28.

353

13.8

2920

13.6

162.

134

2.96

Hf

8.3

7.4

4.2

4.7

4.3

3.1

3.1

6.5

3.3

3.7

2.2

6.9

12.1

10.7

16.6

3.8

6.8

Ho

2.

278

1.57

70.

691

0.74

40.

882

0.54

80.

454

1.29

0.32

70.

484

0.24

51.

964

3.43

44.

555.

993

0.27

20.

706

La

28

.27

56.2

948

.08

46.8

639

.58

25.4

340

.73

23.0

410

.78

17.3

48.

4429

.24

38.4

654

.06

1.26

20.7

117

.53

Lu

1.

245

0.71

80.

447

0.41

30.

486

0.37

40.

296

0.69

50.

182

0.21

20.

128

0.96

71.

681.

953

3.01

90.

114

0.41

9N

b

18.7

15.6

14.8

14.3

8.2

11.3

11.4

11.8

7.4

7.1

1114

.726

.228

.445

.86.

46.

4N

d

38.6

752

.51

30.6

436

.98

36.5

19.2

423

.86

28.9

78.

1615

.71

7.59

36.2

454

.281

.77

9.75

16.6

517

.02

Pr

9.14

513

.921

9.31

510

.288

9.58

65.

489

7.38

6.95

42.

357

4.07

2.31

28.

826

12.5

8618

.395

1.28

14.

659

4.46

4R

b 33

.99

81.3

313

8.05

85.2

251

.63

58.5

291

.68

18.5

426

.99

39.4

863

.68

38.3

147

.14

13.0

222

.98

89.2

675

.28

Sm

8.94

9.78

4.51

5.96

6.44

3.23

3.4

6.5

1.45

2.96

1.53

8.14

12.6

519

.54

7.08

2.77

3.19

Sr

18.1

14.1

117.

217

9.1

236.

219

410

6.6

52.8

108.

622

6.3

86.5

98.5

85.7

84.8

13.4

37.8

93.4

Ta

1.38

1.04

1.27

1.09

0.62

0.98

1.05

0.9

0.88

0.7

11.

041.

631.

762.

940.

71.

02T

b

1.6

1.27

50.

531

0.62

50.

711

0.38

90.

362

0.99

60.

232

0.39

80.

196

1.39

2.40

13.

413.

291

0.27

70.

475

Th

3.73

1513

.86

11.9

79.

779.

8510

.79

3.61

7.23

3.46

1.8

4.97

5.32

5.87

6.97

2.66

4.9

Tm

1.

156

0.72

10.

365

0.36

20.

435

0.30

40.

243

0.61

80.

166

0.20

80.

120.

939

1.64

12.

009

3.05

0.11

20.

371

U

0.89

13.

891

3.33

82.

711

2.25

12.

476

2.72

40.

859

2.11

90.

992

0.72

91.

197

1.19

31.

261

1.54

50.

774

1.29

5Y

60.2

541

.49

19.9

120

.55

24.8

216

.613

.11

35.8

69.

9913

.19

7.67

53.9

190

.32

120

120

7.75

19.8

Yb

7.88

4.81

2.68

2.57

3.02

2.21

1.76

4.33

1.16

1.37

0.8

6.3

10.9

813

.06

19.9

60.

752.

6Zr

29

3.5

302.

715

4.5

197.

717

4.5

116.

711

3.9

257.

610

2.3

145.

348

.623

6.4

443.

636

747

7.6

142.

725

0.6

Be

0.

470.

851.

020.

940.

630.

60.

710.

440.

680.

510.

750.

721.

211.

260.

850.

570.

39C

o 3.

5915

.39

1.91

1.85

6.64

2.4

0.69

12.4

20.

3420

.10.

163.

232.

555.

039.

410

.86

2.18

Cu

2.

7958

.98

15.1

83.

3813

.21

25.1

5.34

10.9

21.

843

.54

1.92

9.42

1.86

3.54

2.71

187

44.7

6L

i 2

326

1616

129

24

223

126

67

26

Ni

2.46

1.51

1.5

2.19

2.43

1.98

0.97

18.2

71.

2366

.61.

182.

341.

615.

741.

797.

85.

35Sc

4.

96.

13.

44.

38.

93

2.3

7.9

0.8

11.2

14.

28

7.7

1.7

4.5

2.2

V

5.67

6.46

16.8

19.

5959

.87

12.9

69.

8422

.03

1.9

99.2

41.

753.

596.

1316

.04

1.31

45.2

10.9

3Zn

11

.84

29.3

226

.34

45.7

554

.69

29.1

17.2

914

3.67

18.5

66.5

617

.268

.17

54.7

47.5

324

27.2

723

.7B

a

200.

0383

4.09

770.

9559

6.12

695.

233

2.89

578.

880

.426

4.95

293.

3561

1.59

367.

5355

0.06

245.

2336

1.75

200.

1419

9.08

Cd

0.

069

0.09

20.

044

0.06

40.

072

0.04

80.

094

0.04

50.

064

0.10

10.

073

0.08

30.

118

0.09

6C

r

8.09

8.19

126.

939.

1514

.81

11.2

Ga

11.7

318

.04

15.9

214

.54

15.6

310

.01

10.8

215

.26

17.2

718

.05

15.2

214

.48

21.4

220

.79

25.0

716

.98

10.4

7M

o

0.22

0.32

1.26

0.24

0.59

0.64

0.33

0.47

0.45

0.51

0.14

2.83

0.46

0.28

0.22

0.98

0.53

Pb

1.6

4.4

7.9

7.6

14.5

9.3

5.1

12.8

6.3

32.

14.

12.

12.

12.

13.

32

Sn

1.49

5.87

1.12

1.46

1.58

0.99

0.79

2.59

2.61

1.8

1.34

2.48

2.88

3.34

101.

040.

72T

l 0.

080.

150.

220.

210.

450.

150.

190.

150.

120.

150.

30.

130.

130.

030.

060.

60.

61W

0.

11.

680.

581.

10.

520.

360.

330.

360.

610.

30.

180.

240.

230.

160.

990.

980.

35

APP

EN

DIX

1(C

ont.)


0361-0128/98/000/000-00 $6.00 1560

Num

ber

R-1

16R

-117

R-1

18R

-119

R-1

20R

-121

R-1

22R

-123

Zone

1817

1717

1717

1717

UT

ME

3132

8064

7800

6478

0070

7947

6300

0062

8000

6270

8062

8025

UT

MN

5330

673

5519

200

5519

500

5358

713

5468

000

5471

000

5474

000

5475

000

SiO

2(%

wt)

69.0

483

.36

79.1

384

.15

83.3

878

.24

72.6

73.3

6A

l 2O3

15.5

55.

495.

728.

594.

6510

.51

12.6

112

.92

TiO

20.

460.

110.

110.

180.

120.

130.

320.

39F

e 2O

32.

794.

935.

510.

436.

231.

983.

433.

68M

gO

1.07

0.55

5.54

0.05

2.57

1.69

4.33

1.91

MnO

0.

030.

10.

040.

020.

060.

05K

2O

1.58

1.8

0.05

4.19

0.04

3.66

2.98

3.95

CaO

0.

730.

240.

410.

010.

270.

060.

04N

a 2O

6.

310.

170.

111.

620.

020.

720.

330.

23P 2

O5

0.34

0.02

0.03

0.03

0.02

0.02

0.05

0.03

LO

I

1.31

3.35

2.9

0.41

1.79

3.27

4.07

3.72

Tota

l 99

.21

99.8

99.4

410

0.08

98.8

810

0.51

100.

8610

0.28

Ce

(pp

m)

85.1

743

.31

24.7

212

7.65

9.54

74.0

456

.53

42.5

4C

s

0.79

90.

446

0.03

40.

260.

022

1.36

90.

768

1.39

2D

y

8.77

62.

762

1.75

7.79

31.

715.

133

3.46

33.

444

Er

5.

759

1.56

31.

135.

191.

093.

471

2.17

42.

108

Eu

1.

686

1.93

80.

592.

007

0.19

0.45

70.

894

0.82

5G

d

10.3

553.

521.

955

9.36

41.

341

5.63

54.

053.

445

Hf

82.

72.

88.

82.

16.

26.

26

Ho

1.

857

0.54

80.

369

1.65

80.

363

1.08

50.

716

0.70

5L

a

33.9

221

.03

11.7

354

.34

4.24

34.4

525

.718

.85

Lu

0.

972

0.23

60.

194

0.81

60.

160.

555

0.32

70.

334

Nb

12

.45.

14.

413

.83.

112

.211

9.8

Nd

51

.67

20.1

111

.04

62.2

14.

6330

.75

24.8

619

.4Pr

11

.78

5.20

62.

859

15.7

811.

148

8.44

56.

604

5.09

4R

b 35

.733

.47

1.24

42.3

30.

9492

.22

56.6

566

.88

Sm

11.9

4.03

2.22

12.1

11.

066.

24.

73.

74Sr

11

03.

55

104.

51.

412

.314

.252

.5Ta

0.

810.

540.

471.

080.

411.

391.

020.

9T

b

1.48

20.

502

0.28

81.

326

0.25

0.86

0.59

50.

557

Th

5.01

1.97

1.93

5.11

1.38

8.54

4.07

2.92

Tm

0.

894

0.23

40.

180.

799

0.16

0.53

90.

320.

322

U

1.20

20.

612

0.46

71.

195

0.42

72.

183

1.16

31.

218

Y 51

.514

.56

10.3

442

.49

10.2

829

.58

19.7

719

.73

Yb

6.11

1.55

1.23

5.3

1.06

3.68

2.16

2.16

Zr

300.

410

1.9

111.

231

3.7

86.1

177.

623

7.3

238.

1B

e

0.93

0.38

0.24

0.38

0.87

0.6

1.19

Co

2.6

7.31

6.54

1.77

12.5

91.

763.

735.

87C

u

167

115.

6611

1.21

6.35

14.5

34.

722.

9227

.85

Li

184

165

1010

134

Ni

5.23

4.52

1.04

5.28

9.24

3.97

2.04

2.76

Sc

14.8

2.7

3.4

4.5

2.4

2.3

3.3

3.7

V

21.2

64.

572.

824.

578.

942.

0714

.64

45.4

1Zn

10

4.7

2790

1559

74.3

540

.07

31.7

936

.68

374

Ba

31

7.34

257.

569.

5217

7.33

6.66

203.

2316

1.29

245.

47C

d

0.23

10.

30.

30.

299

0.04

30.

040.

3C

r

15.2

59.

328.

09G

a 15

.79

5.59

13.7

113

.51

6.46

13.5

514

.63

19.5

8M

o

0.63

0.88

0.34

50.

470.

860.

683.

92Pb

12

.440

4022

.30.

52.

12.

45.

7Sn

2.

681.

161.

83.

421.

913.

677.

2710

Tl

0.26

20.

060.

430.

180.

210.

86W

0.

421.

170.

380.

310.

40.

441.

43.

07

Proj

ectio

n =

NA

D 8

3

APP

EN

DIX

1(C

ont.)


0361-0128/98/000/000-00 $6.00 1561

APPENDIX 2Mineralogy of Felsic Volcanic Rocks as Determined from Thin Section

Phenocrysts Alteration Pl Matrix

Sample District Group Qz Pl Tot Chl Ser Car Qz-Pl Chl Ser Car Epi Hbl Bio Zir Op

R-2003-1 Quévillon FI 10 15 25 10-100 50 6 12 6 1R-2003-2 Quévillon FI 2 2 64 0.5 18 5 0.5 10R-2003-3 Quévillon FI 15 15 15 20 15 35 15R-2003-4 Quévillon FIIIa 4 2 6 5 0.5 70 5 15 1 1 2R-2003-5 Quévillon FIIIa 83 4 10.5 0.5 2R-2003-8 Quévillon FIIIa 4 5 9 5 5 15 15 57 3 1R-2003-9 Quévillon FIIIa 1 2 3 3 3 87 7 3R-2003-10 Val-d'Or FII 80 1 15 4R-2003-11 Val-d'Or FII 60 18 20 2R-2003-12 Val-d'Or FIIR-2003-13 Val-d'Or FIIIaR-2003-14 Val-d'Or FIIR-2003-15 Val-d'Or FII 28 34 34 1 3R-2003-16 Val-d'Or FII 1 1 2 10 70 10 10 6 2R-2003-17 Val-d'Or FIIR-2003-18 Val-d'Or FII 52 28 20R-2003-19 Val-d'Or FII ? 64 8 17 10 1R-2003-20 Val-d'Or FII 69 30 1R-2003-116 Val-d'Or FII 2 2 0-10 20-70 0-7 75 5 15 1 2R-2003-21 NVZ-Ext FII 73 19 8R-2003-22 NVZ-Ext FII 34 34 31 1R-2003-23 NVZ-Ext FIIR-2003-25 NVZ-Ext FII 2 2 4 3-25 20 67 26 2 1R-2003-26 NVZ-Ext FII 10 10 20 20 10-70 42 12 20 5 1R-2003-27 NVZ-Ext FII 3 3 86 10 1R-2003-28 NVZ-Ext FIIR-2003-29 NVZ-Ext FII 5 5 10 90 75 15 2 3R-2003-30 NVZ-Ext FII 1 1 90 30 39 10 20R-2003-31 NVZ-Ext FII 1 3 4 3 20 47 13 23 10 3R-2003-32 NVZ-Ext FII 10 10 0-10 10 0-2 53 1 20 15 1R-2003-37 NVZ-Ext FII 90 5 5R-2003-42 NVZ-Ext FII 0.5 1 1.5 30 33 15 25 3 0.5 11 11R-2003-43 NVZ-Ext FII 0.5 0.5 89.5 7 3R-2003-34 Normétal FIIIa 40 59 1R-2003-35 Normétal FIIIa 81 13 6R-2003-36 Normétal FII 80 5 15R-2003-38 Normétal FIIR-2003-44 Joutel FIIR-2003-45 Joutel FII 1 3 4 6 10 70 11 12 3R-2003-46 Joutel FI 1 3 4 5-20 15 69 10 15 1 1R-2003-47 Joutel FIIIa 3 3 64 30 3R-2003-48 Joutel FIIIa 10 4 14 2 10-80 52 15 15 3 1R-2003-51 Matagami FIIIb 0.5 0.5 1 3 65 8 10 10 6R-2003-52 Matagami FIIIb 0.5 0.5 3 3 75.5 16 3 5R-2003-53 Matagami FIIIb 51 47 2R-2003-54 Matagami FIIIb 70 70 5 20 5R-2003-55 Hunter FII 6 6 100 67 15 10 2R-2003-56 Hunter FII 0.5 0.5 2 5 71 0.5 15 10 3R-2003-57 Hunter FII 2 10 12 5 10 63 5 15 3 2R-2003-58 Hunter FII 1 1 2 5 3-10 2 71 12 10 3 2R-2003-59 Hunter FII 1 6 7 5 10-70 73 5 3 9 3R-2003-60 Hunter FII 1 15 16 0-15 3 0-98 52 18 6 8R-2003-61 Hunter FII 3 17 20 0-80 0-95 13 51 6 10R-2003-62 Hunter FII 0.5 0.5 61.5 19 17 2R-2003-63 Hunter FII 1 1 82 5 10 1 1R-2003-64 Hunter FII 3 3 0-100 76 15 3 3R-2003-65 Hunter FII 5 15 20 10 5-15 55 10 5 5 5R-2003-66 Hunter FII 3 3 51 20 13 7 5 1R-2003-108 Chibougamau FI 15 15 20 60 25 18 35 7R-2003-109 Chibougamau FI 1 3 4 20 1 81.5 7 7 0.5R-2003-110 Chibougamau FII ? 52.5 5 37 0.5 5R-2003-111 Chibougamau FIIIa 2 2 4 1 3 7 20 7 60 7 2R-2003-112 Chibougamau FIIIa 4 10 14 1 10 3 61.5 10 10 1.5 3R-2003-113 Chibougamau FIIIa 4 4 65.5 20 10 0.5R-2003-50 Selbaie FII 0.5 0.5 1 25 5 20 68 5 6R-2003-117 Selbaie FII 3 3 100 65 1 30 1


0361-0128/98/000/000-00 $6.00 1562

R-2003-118 Selbaie FII 0.5 0.5 65 33 1 0.5R-2003-67 Noranda FIIIa Tr 62 15 6 12 5R-2003-68 Noranda FIIIa 0.5 3 3.5 40 3 33.5 8 47 6 2R-2003-69 Noranda FIIIa 0.5 2 2.5 3 3 81.5 3 2 7 4R-2003-70 Noranda FIIIa 1 2 3 91.5 2 1 0.5 2R-2003-71 Noranda FIIIa 67 31 2R-2003-72 Noranda FIIIa 82 10 7 1R-2003-73 Noranda FIIIa 1 1 20 15 52 26 19 2R-2003-74 Noranda FIIIa ? 0.5 0.5 54.5 2 38 5R-2003-75 Noranda FIIIa 5 1 6 10 5-65 2 70 20 3 1R-2003-76 Noranda FIIIa 6 3 9 5 15 3 75 8 3 3 2R-2003-77 Noranda FIIIa 75 6 15 2 2R-2003-78 Noranda FIIIa 1 1 5 5 90 75.5 6 10 7 0.5R-2003-79 Noranda FIIIa 7 7 60 7 15 10 1R-2003-80 Noranda FIIIa 0.5 0.5 2-10 0-10 82.5 1 7 6 3R-2003-81 Noranda FIIIa 79 2 5 12 2R-2003-82 Noranda FIIIa 1 24 25 10 90 15 15 40 5R-2003-83 Noranda FIIIa 0.5 0.5 3 0.5 84.5 4 6 5R-2003-84 Noranda FIIIa 1 1 2 65 12 13 64.5 12 3 0.5 5R-2003-88 Noranda FIIIa 9 1 10 38 2 65 8 6 7 3 1R-2003-89 Noranda FIIIa 0.5 0.5 1 1 5 40 5 50 2 2R-2003-90 Noranda FIIIa 0.5 1 1.5 3 88 5 1 2.5 2R-2003-92 Noranda FIIIa ? 33 33 5 80 5 20 15 10 15 7R-2003-93 Noranda FIIIaR-2003-95 Noranda FIIIaR-2003-96 Noranda FIIIa 7 3 10 1 1 2 60.5 25 3 1 0.5R-2003-97 Noranda FIIIa 8 15 23 3 10 3 49 12 12 2 2R-2003-98 Noranda FIIIa 3 77 80 5 5 0.5 9 3 1 7R-2003-99 Noranda FIIIa 3 0.5 3.5 5 2 71.5 2 7 15 1R-2003-100 Bousquet FI 0.5 0.5 68 0.5 25 3 3R-2003-101 Bousquet FI 5 10 15 3 20 10 50 3 24 3 5R-2003-102 Bousquet FI 50.5 3 40 1 0.5 5R-2003-103 Bousquet FIR-2003-104 Bousquet FI 4 5 9 22 1 60 5 20 5 1R-2003-105 Bousquet FI 3 10 13 5-10 6-10 71.5 1 10 3.5 0.5 0.5R-2003-41 NVZ-ext FI 15 10 25 3-60 48 10 10 7R-2003-85 Kinojevis FII 5 2 7 4 0.5 77.5 15 0.5R-2003-106 Coniagas FII 0.5 1 1.5 1 3 25 15 0.5 55.5 0.5 2R-2003-107 Lac Hébert FI 10 10 20 7 68.5 0.5 9 0.5 0.5 1R-2003-114 NVZ-int FI 3 3 51 35 5 6R-2003-115 NVZ-int FI 0.5 0.5 53 2 25 19 0.5R-2003-119 Marbridge FII 93.5 1 3 2 0.5

Notes: Phenocryst >0.5 mm; abbreviations: Bio = biotite, Car = carbonate, Chl = chlorite, Epi = epidote, Hbl = hornblende, Op = opaque, Pl = plagio-clase, Qz = quartz, Ser = sericite, Zir = zircon

APPENDIX 2 (Cont.)

Phenocrysts Alteration Pl Matrix

Sample District Group Qz Pl Tot Chl Ser Car Qz-Pl Chl Ser Car Epi Hbl Bio Zir Op

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Rhyolite Geochemical Signatures and Association with ...€¦ · rhyolite suites and volcanogenic massive sulfide (VMS) de-posits was promoted as an effective tool for exploration