Geological Survey of Finland - Report of Investigation

7/23/2019 Geological Survey of Finland - Report of Investigation

1/394

Quantitative assessment of undiscovered resourcesin volcanogenic massive sulphide deposits, porphyry copper

deposits and Outokumpu-type deposits in Finland

Rasilainen, K., Eilu, P., Halkoaho, T., Karvinen, A., Kontinen, A., Kousa, J., Lauri, L., Luukas, J.,Niiranen, T., Nikander, J., Sipil, P., Sorjonen-Ward, P., Tiainen, M., Trmnen, T. and Vsti, K.

GEOLOGICAL SURVEY OF FINLAND

Report of Investigation 2082014


2/394

GEOLOGIAN UKIMUSKESKUS GEOLOGICAL SURVEY OF FINLAND

utkimusraportti 208 Report o Investigation 208

Rasilainen, K., Eilu, P., Halkoaho, ., Karvinen, A., Kontinen, A., Kousa, J., Lauri, L., Luukas, J.,Niiranen, ., Nikander, J., Sipil, P., Sorjonen-Ward, P., iainen, M.,

rmnen, . and Vsti, K.

QUANIAIVE ASSESSMEN OF UNDISCOVERED RESOURCES INVOLCANOGENIC MASSIVE SULPHIDE DEPOSIS, PORPHYRY COPPER DEPOSIS ANDOUOKUMPUYPE DEPOSIS IN FINLAND

Front cover: Te Pyhsalmi mine in 2007. Te Pyhsalmi deposit is one o the most important

copper-zinc deposits o all time in Finland.Photo: Pyhsalmi Mine Oy.

Unless otherwise indicated, the figures have been prepared by the authors o the publication.

ISBN 978-952-217-303-4 (pd)

ISSN 0781-4240

Layout: Elvi urtiainen Oy

Espoo 2014


3/394

Rasilainen, K., Eilu, P., Halkoaho, ., Karvinen, A., Kontinen, A., Kousa, J.,Lauri, L., Luukas, J., Niiranen, ., Nikander, J., Sipil, P., Sorjonen-Ward,P., iainen, M., rmnen, . & Vsti, K. 2014. Quantitative assessment oundiscovered resources in volcanogenic massive sulphide deposits, porphyrycopper deposits and Outokumpu-type deposits in Finland. Geological Survey ofFinland, Report of Investigation208,60pages, 19 figures, 9 tables, 7 appendices.

Undiscovered resources o copper, zinc, lead, gold and silver in volcanogenic

massive sulphide (VMS) deposits, undiscovered resources o copper, molybde-num, gold and silver in porphyry copper deposits, and undiscovered resourceso copper, zinc, nickel and cobalt in Outokumpu-type deposits were estimateddown to the depth o one kilometre in the bedrock o Finland using the three-part quantitative assessment method. Grade-tonnage models were constructedor elsic, bimodal-mafic and mafic VMS deposits using data rom known Fen-noscandian deposits. A grade-tonnage model or porphyry copper deposits wasconstructed using global data rom Precambrian deposits. For the Outokum-pu-type deposits, a grade-tonnage model was developed using data rom well-known deposits within the Outokumpu area. Tirty-one permissive tracts weredelineated or VMS deposits, 10 or porphyry copper deposits, and one or Outo-kumpu-type deposits. Te VMS tracts cover an area o 41,600 km2, the por-phyry copper tracts cover 38,400 km2, and the Outokumpu tract covers 9800km2. Te mean estimates o the numbers o undiscovered VMS, porphyry cop-

per and Outokumpu-type deposits within the permissive tracts are 45, 11 and 6,respectively. At 50 % probability, the undiscovered VMS deposits are estimatedto contain at least 730,000 t Cu, 1.6 Mt Zn, 150,000 t Pb, 1100 t Ag and 16 tAu, and the undiscovered porphyry copper deposits are estimated to contain atleast 2.4 Mt Cu, 100,000 t Mo, 1000 t Ag and 170 t Au. Te estimated medianundiscovered resources in Outokumpu-type deposits are at least 580,000 t Cu,220,000 t Zn, 53,000 t Co and 41,000 t Ni. About 71 % o the copper and 68 % othe zinc endowment in VMS and Outokumpu-type deposits, and at least 98 %o the copper endowment in porphyry copper deposits in Finland occurs inpoorly explored and undiscovered deposits. Te undiscovered VMS resourcesare estimated to be distributed between several permissive tracts, with the Vi-hanti and Pyhsalmi tracts having the largest undiscovered resources. Felsic de-posits are estimated to contain 53 % o the undiscovered VMS-type copper-zincresources and 95 % o the undiscovered VMS-type lead resources in Finland.Te undiscovered porphyry copper resources are estimated to be concentratedin the Central Ostrobothnia, ampere, Hme and Haaparanta tracts, with 86 %o the resources in central and southern Finland. At the 50 % level o prob-ability, the undiscovered copper-zinc resources in VMS, porphyry copper andOutokumpu-type deposits in Finland are at least 3.7 Mt o copper and 1.8 Mto zinc. Tis is 38 % o the total estimated undiscovered copper resources and100 % o the total estimated undiscovered zinc resources in Finland.

Keywords (GeoRe Tesaurus, AGI): copper, zinc, massive sulfide deposits,porphyry copper, undiscovered resources, evaluation, ore grade, tonnage,quantitative analysis, intrusions, Proterozoic, Archean, Finland

Kalevi RasilainenGeological Survey of FinlandPO Box 96FIN-02151 ESPOOFINLAND

E-mail: [email protected]


4/394

Rasilainen, K., Eilu, P., Halkoaho, ., Karvinen, A., Kontinen, A., Kousa, J.,Lauri, L., Luukas, J., Niiranen, ., Nikander, J., Sipil, P., Sorjonen-Ward, P.,iainen, M., rmnen, . & Vsti, K. 2014.Quantitative assessment o undis-covered resources in volcanogenic massive sulphide deposits, porphyry copperdeposits and Outokumpu-type deposits in Finland. Geologian tutkimuskeskus,Tutkimusraportti 208. 60sivua, 19 kuvaa, 9 taulukkoa, 7 liitett.

Vulkanogeenisiin massiivisiin sulfidimalmeihin (VMS) liittyvt lytmttmt

kupari-, sinkki-, lyijy-, kulta- ja hopeavarannot, poryyrikupariesiintymiin liit-tyvt lytmttmt kupari-, molybdeeni-, kulta- ja hopeavarannot sek Outo-kumpu-tyyppisiin esiintymiin liittyvt lytmttmt kupari-, sinkki-, nikkeli-

ja kobolttivarannot Suomen kallioperss arvioitiin yhden kilometrin syvyyteenasti kytten kolmivaiheista kvantitatiivista menetelm. Felsisille, bimodaalis-mafisille ja mafisille VMS-esiintymille rakennettiin tonnimr-pitoisuusmallittunnettujen Fennoskandian kilvell sijaitsevien esiintymien perusteella. Por-yyrikupariesiintymille tehtiin tonnimr-pitoisuusmalli kytten maailman-laajuista aineistoa prekambrisista esiintymist. Outokumpu-tyypin esiintymi-en tonnimr-pitoisuusmalli koottiin kytten hyvin tunnettuja esiintymiOutokumpu-alueelta. VMS-esiintymille mritettiin 31 sallittua esiintymis-aluetta, poryyrikupariesiintymille kymmenen ja Outokumpu-tyypin esiinty-mille yksi. VMS-tyypin alueet kattavat 41 600 km2, poryyrikuparityypin 38 400km2 ja Outokumpu-tyypin 9 800 km2. Sallituilla esiintymisalueilla sijaitsevien

lytmttmien VMS-esiintymien, poryyrikupariesiintymien ja Outokumpu-tyypin esiintymien arvioitujen lukumrien keskiarvot ovat 45, 11 ja 6. Lyt-mttmien VMS-esiintymien arvioidaan sisltvn 50 %:n todennkisyydellainakin 730 000 t Cu, 1,6 Mt Zn, 150 000 t Pb, 1 100 t Ag ja 16 t Au. Lytmtt-mien poryyrikupariesiintymien arvioidaan sisltvn 50 %:n todennkisyy-dell ainakin 2,4 Mt Cu, 100 000 t Mo, 1 000 t Ag ja 170 t Au. Mediaaniarvionmukaan lytmttmien Outokumpu-tyypin esiintymien mineraalivarannotovat vhintn 580 000 t Cu, 220 000 t Zn, 53 000 t Co ja 41 000 t Ni. Aina-kin 71 % Suomen VMS- ja Outokumpu-tyypin esiintymien kuparisisllst ja68 % niiden sinkkisisllst sek ainakin 98 % Suomen poryyrikuparityypinesiintymien kuparisisllst on heikosti tutkituissa ja lytmttmiss esiinty-miss. Lytmttmien VMS-tyypin mineraalivarantojen arvioidaan jakautu-

van monelle sallitulle alueelle, ja Vihanti- ja Pyhsalmi-alueilla ovat suurimmatlytmttmt varannot. Felsiset esiintymt sisltvt arviolta 53 % Suomenlytmttmist VMS-tyyppisist kupari-sinkkivarannoista ja 95 % lytmt-tmist lyijyvarannoista. Lytmttmien poryyrikuparivarantojen arvioi-daan keskittyneen Keski-Pohjanmaan, ampereen, Hmeen ja Haaparannansallituille alueille, ja 86 % varannoista sijaitsee Keski- ja Etel-Suomessa. Ly-tmttmt kupari-sinkkivarannot Suomen VMS-, poryyrikupari- ja Outo-kumpu-tyypin esiintymiss ovat 50 %:n todennkisyydell ainakin 3,7 Mt ku-paria ja 1,8 Mt sinkki. m on 38 % kaikista arvioiduista lytmttmistkuparivarannoista ja 100 % kaikista arvioiduista lytmttmist sinkkivaran-noista Suomessa.

Julkaisu on englanninkielinen.

Asiasanat (Geosanasto, GK): kupari, sinkki, massiiviset sulfidiesiintymt, por-

yyrikupari, lytmttmt varannot, arviointi, malmipitoisuus, tonnimr,kvantitatiivinen analyysi, intruusiot, proterotsooinen, arkeeinen, Suomi

Kalevi RasilainenGeologian tutkimuskeskusPL 9602151 ESPOO

S-posti: [email protected]


5/394

4

Geologian tutkimuskeskus, Tutkimusraportti 208 Geological Survey of Finland, Report of Investigation 208, 2014Rasilainen, K., Eilu, P., Halkoaho, T., Karvinen, A., Kontinen, A., Kousa, J., Lauri, L., Luukas, J., Niiranen, T., Nikander, J., Sipil, P.,Sorjonen-Ward, P., Tiainen, M., Trmnen, T. and Vsti K.

4

CONENS

1 INRODUCION ........................................................................................................................................... 7 1.1 Te Geological Survey o Finland assessment project .........................................................................7 1.2 erminology ..............................................................................................................................................9

2 Cu-Zn DEPOSI YPES IN FINLAND .......................................................................................................9 2.1 Volcanogenic massive sulphide deposits ............................................................................................11 2.1.1 Felsic type: Te Pyhsalmi deposit ............................................................................................. 12 2.1.2 Bimodal-mafic type: Te Rauhala deposit ................................................................................. 15 2.1.3 Mafic type: Te Hllinmki deposit ........................................................................................... 17

2.2 Porphyry copper deposits ......................................................................................................................21 2.2.1 Te Kopsa deposit ......................................................................................................................... 21 2.3 Outokumpu-type Cu-Zn-Co deposits .................................................................................................23 2.3.1 Te Kylylahti deposit .................................................................................................................... 23

3 HE HREE-PAR QUANIAIVE RESOURCE ASSESSMEN MEHOD ................................ 27 3.1 Deposit models .......................................................................................................................................27 3.1.1 Descriptive models ....................................................................................................................... 27 3.1.2 Grade-tonnage models ................................................................................................................. 27 3.2 Permissive tracts .....................................................................................................................................28 3.3 Estimation o the number o undiscovered deposits .........................................................................28 3.4 Statistical evaluation ...............................................................................................................................29

4 ASSESSMEN OF Cu-Zn RESOURCES IN FINLAND ...........................................................................29 4.1 Resources covered by the assessment ...................................................................................................29 4.2 GK assessment process ........................................................................................................................29 4.3 Data used .................................................................................................................................................30 4.3.1 Geology .......................................................................................................................................... 30 4.3.2 Known mineral deposits and occurrences ................................................................................ 30 4.3.3 Geophysical and geochemical data ............................................................................................. 30 4.3.4 Exploration history ....................................................................................................................... 30

4.4 Deposit models .......................................................................................................................................30 4.4.1 Volcanogenic massive sulphide (VMS) deposits ...................................................................... 30 4.4.2 Porphyry copper deposits ............................................................................................................ 34 4.4.3 Outokumpu-type Cu-Zn-Co deposits ....................................................................................... 35 4.5 ract delineation .....................................................................................................................................36 4.6 Estimation o the number o undiscovered deposits .........................................................................36 4.7 Assessment o metal tonnages ...............................................................................................................39

5 RESULS AND DISCUSSION .................................................................................................................... 39 5.1 Permissive tracts delineated ..................................................................................................................41 5.2 Undiscovered resources in VMS deposits, Outokumpu-type deposits and

porphyry copper deposits ......................................................................................................................41 5.3 Finnish Cu-Zn endowment in the global context ..............................................................................50


6/394

5

Geologian tutkimuskeskus, Tutkimusraportti 208 Geological Survey of Finland, Report of Investigation 208, 2014Quantitative assessment of undiscovered resources in volcanogenic massive sulphide deposits, porphyry copper deposits and

Outokumpu-type deposits in Finland

5.4 Reliability and usability o the estimates ..............................................................................................51

6 SUMMARY ......................................................................................................................................................52ACKNOWLEDGMENS ..................................................................................................................................54

REFERENCES ......................................................................................................................................................54

APPENDICES ......................................................................................................................................................61

Appendix 1 ...........................................................................................................................................................61 Descriptive model o volcanogenic massive sulphide (VMS)

Appendix 2 ...........................................................................................................................................................65 Grade-tonnage model o Fennoscandian volcanogenic massive sulphide (VMS)

Appendix 3 ...........................................................................................................................................................76

Descriptive model o porphyry copper (gold, molybdenum)

Appendix 4 ...........................................................................................................................................................79 Grade-tonnage model o Precambrian porphyry copper

Appendix 5 ...........................................................................................................................................................83Descriptive model o Outokumpu-type Cu-Zn-Co

Appendix 6 ...........................................................................................................................................................88Grade-tonnage model o Outokumpu-type Cu-Zn-Co

Appendix 7 ...........................................................................................................................................................91Assessment results or VMS, porphyry copper and Outokumpu-type Cu-Zn-Copermissive tracts in Finland


7/394

6



8/394

7



7

1 INRODUCION

Troughout the history o humankind, the de-mand or mineral resources has increased with thecontinuing growth o the world population andthe rise in the average material standard o living.In tandem with this trend, exploration or and thedevelopment o new mineral resources all overthe world have aced increasing competition romother land uses (e.g., Briskey et al. 2007, Cunning-ham et al. 2007, Hitzman 2007, Idman et al. 2007).

Concerns about the environmental effects o min-ing are also having a growing influence on the costand pace o development o new natural resources.In the modern world, Finland can no longer relyon the ready availability o imported raw materialsor manuacturing and other industries. Tis ap-plies to the entire European Union, which is glob-ally a major net importer o nearly all metallic oresand concentrates (Kauppa- ja teollisuusministeri2006, Commission o the European Communities2008, European Commission 2011). We need toknow our mineral resources and how they mightbe expanded. Essential inormation includes thelocation o known resources, the location andamount o the possibly existing, yet undiscoveredresources, and the uncertainty related to their ex-istence. Furthermore, it is important to know howthe development o mineral deposits will affect

other surrounding resources, such as biologicaldiversity, arable land, air and water.

Tis report aims to answer the questions whereand how much we could still expect to find, givenall that we have already discovered and used. Wedescribe the process and results o a quantitativeassessment o copper (Cu), zinc (Zn), lead (Pb),silver (Ag), and gold (Au) resources in undiscov-ered volcanogenic sulphide (VMS), Outokumpu-

type polymetallic and porphyry copper depositsin Finland. Te report comprises two parts. Tefirst part reviews the types o VMS, Outokumpuand porphyry copper deposits in Finland and theirgeological environments, the assessment method,the data used, and the assessment process itsel. Asummary o the assessment results is given and theresults are discussed. Te second part comprisesthe Appendices, which include the deposit modelsemployed and detailed inormation on each per-missive tract delineated.

Te inormation provided here on the locationand amount o undiscovered mineral resources isexpected to be valuable or effective land use plan-ning and the sustainable development o mineralresources, and also in evaluating the long-termproductivity o investments in exploration and re-lated research and education.

1.1 Te Geological Survey o Finland assessment project

Te demands defined above, and requests o vari-ous stake holders (including the National AuditOffice o Finland) to produce exact inormation onpotential resources, resulted in the initiation o theproject National resources o useul minerals atthe Geological Survey o Finland (GK) in 2008.Te project was established to produce unbiasedinormation on undiscovered mineral resourcesor national and regional planning o land use,natural resources management and environmen-tal actions, as well as to develop assessment tools

and enhance their proper application in the con-ditions o Finnish bedrock. Te work done and

results produced will enable accounting o metal-lic natural resources according to the principleso sustainable development. Te project providesnew inormation or metallogenic and lithologicalresearch and or national-level planning o min-eral exploration.

Te project started in 2008 with the selectiono the working methods. Te assessment o plat-inum-group element (PGE) resources was com-pleted and published in 2010 (Rasilainen et al.2010a, b), and the results or nickel (Ni) resources

were published in 2012 (Rasilainen et al. 2012). Atthe beginning o 2011, the name o the project was


9/394

8


changed to Mineral raw materials in Finland andFennoscandia. Te results o the assessment o Cu,Zn, Pb, Ag and Au resources in VMS, Outokum-pu-type and porphyry deposits are presented inthis report, and the Au resources in orogenic golddeposits will be assessed in a report later in 2014.

Te outputs o the project include national and ar-eal mineral resource estimates, and a final reportcontaining a summary o the results or all metalsassessed, a description o the methods and inter-national reerence materials used, and an evalua-tion o the quality o the results.

Te procedure selected or the GK assessmentsis based on the three-part quantitative assessmentmethod developed by the U.S. Geological Survey(USGS) starting rom the mid-1970s (Singer 1993,Singer and Menzie 2010). It must be emphasized

that the method does not provide mineral resourceor reserve estimates concordant with the presentindustrial standards such as the JORC, CRIRSCO,NI 43-101, PERC and UNFC codes (United Na-tions Economic Commission or Europe 2009, Na-tional Instrument 43-101 2011, Joint Ore Reserves

Committee o the Australasian Institute o Miningand Metallurgy, Australian Institute o Geoscienc-es and Mineral Council o Australia 2012, Com-mittee or Mineral Reserves International Report-ing Standards 2013, PanEuropean Reserves andResources Reporting Committee 2013). Te re-

sults o undiscovered resource assessments shouldnever be conused with proper reserve or resourceestimates based on international standards. Rath-er, the assessment process produces probabilisticestimates o the total amount o metals in situ inundiscovered deposits down to the depth o onekilometre. Te modification o the process used inGK assessments does not take into account theeconomic, technical, social or environmental ac-tors that might in the uture affect the potential oreconomic utilisation o a resource. Hence, part o

the estimated undiscovered resources may be lo-cated in subeconomic occurrences (Fig. 1), and itmight be more appropriate to use the term metalendowment, which is not directly dependent oneconomic or technological actors (Harris 1984).

IDENTIFIED RESOURCES UNDISCOVERED RESOURCES

Demonstrated Probability range

Measured Indicated Inferred Hypothetical Speculative

Economic

Marginallyeconomic

Subeconomic

Three-partassessment

CRIRSCO, JORC, NI 43-101,

PERC, UNFC

E

conomicfeasibility

Geologic certainty

Fig. 1. Classification o mineral resources used in GK assessments (modified rom U.S. Geological Survey National MineralResource Assessment eam 2000). Economic easibility increases upwards and geological uncertainty increases to the right.


10/394

9



1.2 erminology

Some terms essential to the proper understand-ing o this report are briefly described below. Tedefinitions ollow the usage by the minerals indus-try and the resource assessment community (U.S.Bureau o Mines and U.S. Geological Survey 1980,U.S. Geological Survey National Mineral ResourceAssessment eam 2000, Committee or MineralReserves International Reporting Standards 2013).

Mineral depositA mineral occurrence o sufficient size and gradethat it might, under the most avourable circum-stances, be considered to have economic potential.

Well-known mineral deposit

A completely delineated mineral deposit, orwhich the identified resources and past produc-tion ore known.

Undiscovered mineral depositA mineral deposit believed to exist less than 1 kmbelow the surace o the ground, or an incomplete-ly explored mineral occurrence within that depthrange that could have sufficient size and grade tobe classified as a deposit.

Mineral occurrenceA concentration o any useul mineral ound inbedrock in sufficient quantity to suggest urtherexploration.

Mineral resourceA concentration or occurrence o material o eco-nomic interest in or on the Earths crust in such aorm, quality and quantity that there are reason-able prospects or eventual economic extraction.

Te location, quantity, grade, continuity and othergeological characteristics o a mineral resource areknown, estimated or interpreted rom specific ge-ological evidence, sampling and knowledge.

Identified resourcesResources whose location, grade, quality andquantity are known or can be estimated rom spe-cific geological evidence.

Well-known resourcesIdentified resources that occur in completelydelineated deposits included in grade-tonnagemodels.

Discovered resourcesTe total amount o identified resources and cu-mulative past production.Undiscovered resourcesResources in undiscovered mineral deposits whoseexistence is postulated based on indirect geologi-cal evidence.

Hypothetical resourcesUndiscovered resources in known types o mineral

deposits postulated to exist in avourable geologi-cal settings where other well-explored deposits othe same types are known.

Speculative resourcesUndiscovered resources that may occur either inknown types o deposits in avourable geologicalsettings where mineral discoveries have not beenmade, or in types o deposits as yet unrecognizedor their economic potential.

2 Cu-Zn DEPOSI YPES IN FINLAND

Copper and zinc are the main or minor commodi-ties in several types o ore deposits in Finland. Tisreport covers three important deposit types wherecopper, zinc or both occur as main commodities:

volcanogenic massive sulphide (VMS) deposits,porphyry copper deposits and Outokumpu-typeCu-Zn-Co deposits. VMS and Outokumpu-type

deposits have produced 1.8 Mt copper and 3.2 Mtzinc, which is over 90 % the total cumulative pro-

duction o these metals in Finland. Tese two de-posit types are estimated to contain about 538,000t o copper and 859,000 t o zinc in well-knownresources, which is respectively 11 % and 8 % oall the well-known copper and zinc resources inFinland (able 1). Porphyry copper deposits areincluded in this assessment due to recent discov-

eries indicating the potential or this deposit typein Finland. Te VMS, porphyry copper and Outo-


11/394

10


kumpu-type deposits are described in more detailin the ollowing subsections.

Te single most important resource o copperand zinc in Finland is the giant alvivaara dissemi-nated to semi-massive strata-bound Ni-Zn-Cu-Codeposit in Palaeoproterozoic (2.11.90 Ga) car-bonaceous metasedimentary rocks o the Kainuuschist belt in eastern Finland (Loukola-Ruskeenie-mi & Heino 1996, Loukola-Ruskeeniemi 1999).alvivaara contains an identified resource o 2.7Mt o copper and 10 Mt o zinc. Another majorsource o copper is the Kevitsa Ni-Cu-PGE deposithosted by a Palaeoproterozoic (~2.05 Ga) layered

intrusion in northern Finland (Mutanen 1997,Gregory et al. 2011). Kevitsa contains an identifiedresource o 1.1 Mt o copper. Tese two depositsare unique in style; no other deposits o either typeare known. Hence, it was not possible to constructgrade-tonnage models or alvivaara- or Kevitsa-type deposits, which in turn made it impossibleto quantitatively assess the possible undiscoveredresources o these two deposit types.

Copper also occurs in Ni-Cu deposits associ-ated with Svecoennian (~1.891.87 Ga) mafic-

ultramafic intrusions in central and southern Fin-land, in Ni-Cu deposits associated with Archaean(~2.8 Ga) komatiitic rocks in eastern and northernFinland and Palaeoproterozoic (~2.05 Ga) komati-itic rocks in northern Finland, and in Ni-Cu-PGEdeposits associated with Palaeoproterozoic (~2.45Ga) mafic-ultramafic layered intrusions in north-ern Finland. Te copper resources in these deposit

types have previously been assessed (Rasilainen etal. 2010a,b, 2012).

Several other deposit types having copper as amajor or minor commodity were excluded romthe assessment or a variety o reasons. A num-ber o small Ni-Cu deposits associated with Jatu-lian-age diabase dykes are known in SW Finland(Puustinen et al. 1995). Since these deposits aresmall and ew in number, their importance orthe total copper endowment in Finland is negli-gible and they were not included in this assess-ment. Tere are some indirect indications orsediment-hosted stratiorm copper as well as

subaerial volcanic-hosted (red bed type?) cop-per in the Perpohja schist belt, in Kuusamo andin other Karelian schists, especially in northernFinland (Kylkoski 2007, 2009, Kylkoski & Eilu2012). However, no obvious examples o these de-posit types are known in Finland and they wereexcluded rom the assessment. Te possible ironoxide-copper-gold (IOCG) deposits in northernFinland (Eilu & Pankka 2009) are mostly iron de-posits where copper and gold orm less than 10 %o the in situ value o a deposit. Hence, undiscov-

ered IOCG deposits were not assessed. Te Kuusa-mo-type Au-CoCu deposits in the Kuusamo areaand the Au-Cu occurrences in the Perpohja schistbelt in northern Finland contain copper only as aminor commodity and were not considered im-portant or the copper assessment. Tese two min-eralisation styles were included in the assessmento gold deposits in Finland (Eilu et al. 2014).

able 1. Well-known resources and cumulative production o copper and zinc or VMS, Outokumpu and porphyry Cudeposits in Finland.

Well-known resources Cumulative production

Deposit type Cu (t) Zn (t) Cu (t) Zn (t)

VMS 341,000 745,000 637,000 2,830,000

Outokumpu 197,000 114,000 1,161,000 334,000

Porphyry Cu 45,000 - - -Total 583,000 859,000 1,798,000 3,164,000

- : Not present in significant amounts.Resources and production as of the end of 2012.The resource and production figures are rounded to full thousands.Data sources: Puustinen (2003) and those listed in Appendices 2, 4 and 6. For mines op-erated after 2001, company reports and news releases were used.


12/394

11



2.1 Volcanogenic massive sulphide deposits

VMS deposits have historically been the most im-portant source or zinc in Finland and the secondmost important source or copper afer the Outo-kumpu-type deposits. By the end o 2012, VMSdeposits had produced about 0.64 Mt Cu and 2.8Mt Zn in Finland (able 1). However, the well-known VMS resources were only 0.34 Mt Cu and0.75 Mt Zn, which are small compared to the totalwell-known resources o 4.9 Mt o Cu and 11 Mt oZn in Finland.

Based on the associated lithology, VMS depositscan be classified into mafic-ultramafic, siliciclas-tic-mafic, bimodal-mafic, bimodal-elsic and si-liciclastic elsic types (Franklin et al. 2005, Galley

et al. 2007, Shanks & Turston 2012). In this as-sessment, we ollow the simplified threeold clas-sification o VMS deposits (Mosier et al. 2009) intomafic, bimodal-mafic and elsic types. Tis clas-sification is based on the observed differences inore tonnage and metal grades between the mafic,bimodal-mafic and elsic types. Finnish exampleso the three types o VMS deposits are briefly de-scribed in the ollowing sections (Figs 212). Adescriptive model or VMS deposits is presentedin Appendix 1 and grade-tonnage models orFennoscandian VMS deposit types are given inAppendix 2.

0 50 100 km

Rapakivi granitesSedimentary rocks

Intrusive rocks

Supracrustal rocks

Intrusive rocks and gneisses

Supracrustal rocks

Palaeo-Mesoproterozoic

Palaeoproterozoic

Archaean

Joensuu

Kuopio

Jyvskyl

Kokkola

Pyhsalmi - Fig. 3

Rauhala - Fig. 5

Kopsa - Fig. 9

Kylylahti - Fig. 11

Hllinmki - Fig. 7

Mikkeli

Iisalmi

Fig. 2. Index map showing the locations o the Pyhsalmi, Rauhala, Hllinmki, Kopsa and Kylylahti deposits and the areascovered by Figs. 3, 5, 7, 9 and 11.


13/394

12


2.1.1 Felsic type: Te Pyhsalmi deposit

Te Pyhsalmi deposit is an example o the bimod-al-elsic type, which alls into the elsic category inthe simplified threeold classification used in thisassessment. Sixteen o the 20 well-known VMS de-

posits in Finland belong to the elsic type, whichmakes it by ar the most common and importantcategory o VMS deposits in the country.

Te Pyhsalmi deposit is located in the villageo Ruotanen in Pyhjrvi municipality, 120 kmnorthwest o the city o Kuopio (Fig. 2), and it wasdiscovered in 1958 on the basis o a layman sample.Te mine started as an open pit operation in 1962,and rom 1976 onwards, all production has beenrom underground. A deep continuation o theorebody was discovered in 1996, which extended

the mine lie by approximately 20 years. Cumula-tive production at the end o 2012 was 51 Mt oore containing 0.45 Mt Cu and 1.2 Mt Zn, whereasthe known remaining resources were 17 Mt con-taining 0.14 Mt Cu and 0.20 Mt Zn (Puustinen2003, Inmet Mining Corporation 2013, . Mki2010 pers. comm.). Te estimated remaining minelie in 2014 was five years (. Mki pers. comm.2014). Te Pyhsalmi deposit and its surround-ings are described in Helovuori (1979), Huhtala(1979), Mki (1986), Ekdahl (1993), Lahtinen

(1994), Kousa et al. (1994, 1997), Balint & Boaro2002, Mki & Puustjrvi (2003) and Rasilainen etal. (2003).

Te Svecoennian bedrock in the Pyhsalmiarea belongs to the Savo belt, which trends north-west between an Archaean basement in the eastand rocks o the Central Finland granitoid com-plex in the southwest (Khknen 2005). Te areais characterised by crustal-scale tectonic blocks odiffering lithological and metamorphic eatures,produced by the overlapping o the northwest-trending Raahe-Ladoga zone and the southwest-trending Oulujrvi shear zone. Te Savo beltmainly consists o moderately to highly metamor-phosed and migmatised turbiditic mica gneisseswith intercalations o volcanic rocks, graphite-bearing schists and minor carbonate rock, skarnand uranium-bearing phosphate beds (Huhtala1979, iks 1989, Ekdahl 1993). Te compositiono intrusive rocks mainly varies rom quartz dior-ite to granite; mafic and ultramafic intrusions are

subordinate.Volcanic rocks in the northwestern part o theSavo belt are divided into two major units based

on age and compositional differences (Kousa et al.1994). Te younger unit, to the west and northwesto the Pyhsalmi area, contains the 1.851.89 GaYlivieska group calc-alkaline basalts to potassiumrhyolites with island arc affinity and well-preservedprimary structures indicating a subaerial or shal-

low-water depositional environment (Kousa et al.1994, Mki & Puustjrvi 2003). Te older unit,which contains all the known VMS deposits in thearea, mostly consists o a 1.921.93 Ga bimodal as-sociation o low-K basalts, basaltic andesites andrhyolites with arc affinity (Kousa et al. 1994), inter-preted to have ormed on an island arc crust thathad been attached to the Keitele microcontinentprior to 1.92 Ga (Lahtinen et al. 2005).

Te 1.921.93 arc assemblage consists o the Py-hsalmi group volcanic rocks and the stratigraphi-

cally overlying Vihanti group volcanic rocks (Fig.3). Te Pyhsalmi deposit is hosted by altered el-sic volcanic rocks o the Pyhsalmi group, whereasthe Mullikkorme deposit seven kilometres to thenortheast occurs within the Vihanti group rocks.Te lowest part o the volcanic sequence in thePyhsalmi area consists o elsic mass flows andtuffaceous and pyroclastic rocks with minor maficintercalations. Mafic massive lavas, pillow lavas,pillow breccias and pyroclastic rocks become moreabundant towards the stratigraphic top. Te rocks

were metamorphosed in upper amphibolite aciesconditions, but retrograde metamorphic mineralassemblages are seen in D

4 shear zones (Mki &

Puustjrvi 2003). Much o the original volcanictextures has been destroyed by hydrothermal al-teration and later tectonic events, but locally themetavolcanic rocks are well preserved.

Most o the elsic volcanic rocks o the Py-hsalmi group are low- to medium-K rhyolites,transitional between tholeiitic and calc-alkalineaffinity (Rasilainen et al. 2003). Te mafic meta-

volcanic rocks are sub-alkaline low- to medium-Ktholeiitic basalts and basaltic andesites. race ele-ment chemistry o the Mukurinper member ba-saltic rocks in the upper part o the stratigraphicsequence and overlying the Pyhsalmi deposit in-dicates a mature island arc setting (Rasilainen etal. 2003), although elsic volcanic and subvolcanicrocks at a stratigraphically lower position belowthe Pyhsalmi deposit have a juvenile Nd isotopesignature (Lahtinen 1994).

Although most o the Pyhsalmi orebody hasnow been excavated, we describe it here using thepresent tense. Te orebody orms a roughly north-


14/394

13



Vihanti group

Intermediate volcanic rock

Granodiorite

Granite, feldspar porphyry,pegmatite

Quartz diorite

Intrusive rocks

Diorite

Diabase

Pyhsalmi group

Felsic volcanic rock

Mafic volcanic rock

Altered felsic volcanic rock

Altered mafic volcanic rock

Sulphide ore


0 0.5 1 km

Mafic volcanic rock

Calc-silicate rock

Fig. 3. Simplified geology around the Pyhsalmi deposit. Map based on Geological Survey o Finland (2010a).


15/394

14


east-trending, S-shaped, 650-m-long and up to75-m-wide intersection with the surace (Fig. 3).Te orebody shortens as it continues almost verti-cally down to the depth o 1416 m, where it endsin a tight old (Fig. 4). Te deep orebody occursbelow the depth o 1050 m rom the surace, and it

contains approximately 35 Mt o sulphides (Mki& Puustjrvi 2003). Te deep orebody is zonedand consists o a core o massive pyrite with lowcopper and zinc grades, a surrounding zone omassive chalcopyrite-pyrite ore and an outer rimo massive to semimassive sphalerite-pyrite ore. Adiscontinuous area o galena-chalcopyrite miner-alisation containing relatively high gold and silvergrades occurs outside o the massive sulphides(Balint & Boaro 2002).

Te coarse-grained Pyhsalmi massive sulphide

ore contains 75 % sulphides with pyrite, chalcopy-rite, sphalerite and pyrrhotite as the main miner-als. Accessory minerals include galena, magnet-ite, arsenopyrite and various sulphosalts (Mki& Puustjrvi 2003). Barite, carbonate, mica andquarts occur as the main gangue minerals. Hostrock inclusions in the sulphide ore are commonand consist mainly o calcareous rocks as well aselsic and mafic volcanic rocks. Te average chem-ical composition o the total deposit is 0.90 % Cu,2.18 % Zn, 0.4 g/t Au and 14 g/t Ag (Appendix 2,

able 1).Several types o sulphide ore can be recognized,

including massive pyrite, massive chalcopyrite-pyrite, massive chalcopyrite-sphalerite-pyrite,massive banded sphalerite-pyrite, semi-massivebreccia sphalerite-barite-carbonate-pyrite, brecciachalcopyrite in host rock inclusions, and pyrrho-tite-bearing varieties (Balint & Boaro 2002). Teorebody can be roughly classified in two types, cop-per-pyrite ore and zinc ore. Te copper-rich partsmostly consist o massive pyrite-chalcopyrite. Noclear eeder zones have been discovered, but hostrock inclusions occasionally contain breccia-typemineralisation with high copper contents. Tezinc-rich pyrite-sphalerite ore is either massive orsemi-massive with high barite and carbonate con-tents (Mki & Puustjrvi 2003). Te distribution ocopper- and zinc-rich ore types is variable in theupper parts o the deposit, but a clearer zoning ispresent in the deep orebody.

Te Pyhsalmi orebody is surrounded by a de-

ormed north-trending alteration zone, whichis our kilometres long and up to one kilome-tre wide at the surace. Te length and width o

600 m

1400 m

1000 m

500 m

N

Deep

oreb

ody

Openpit

Mainshaft

Timoshaft

Ventilationshaft

Fig. 4. Vertical 3D sketch o the Pyhsalmi orebody showingshafs and declines. Modified rom a picture received rom

. Mki (pers. comm. 2014).


16/394

15



the alteration zone decrease with depth, until thewhole zone gradually disappears below the deptho 1150 m. At deeper levels, altered rocks occuronly as inclusions within the orebody. Altered el-sic volcanic rocks contain sericite- and cordierite-bearing mineral assemblages, whereas cordierite,

anthophyllite and garnet characterise altered maficvolcanic rocks.Te contact between the ore and wall rocks is

sharp and sheared, and in places pegmatite dykeshave intruded the contact zone, indicating that D

4

deormation had a strong influence on the finalemplacement o the massive sulphides (Mki &Puustjrvi 2003). Te overall orm and contacts othe orebody indicate a ductile deormation history(Balint & Boaro 2002).

2.1.2 Bimodal-mafic type: Te Rauhala deposit

Rauhala is the only well-known bimodal-maficVMS deposit in Finland. Te deposit is locatedin western Finland, approximately 90 km east-northeast o the town o Kokkola (Fig. 2). It wasdiscovered in 1985 afer a three-year period oexploration initiated by an anomalously high zincconcentration in a regional geochemical sample(Iisalo 1989). Te Rauhala mining concession ispresently held by Pyhsalmi Mine Oy, but the de-

posit has not been mined. Te known resources othe deposit are 1.7 Mt o ore containing 0.023 Mt ocopper and 0.081 Mt o zinc (Vsti 1989). Te Rau-hala deposit and its surroundings are describedin Kojonen et al. (1987, 1989), Puustjrvi (1988),Vsti (1988, 1989, 1993), Iisalo (1989), Jokinenet al. (1989), Rasilainen & Vsti (1989), Vaasjoki(1989), Korkalo (1991), Poutiainen (1992) andKousa et al. (1997).

Te Svecoennian supracrustal rocks in theRauhala area belong to the 1.871.90 Ga Ylivieskagroup within the Pohjanmaa belt (Khknen 2005,Geological Survey o Finland 2010a). Te volcanicrocks range rom basalts to K-rhyolites and have acalc-alkaline, mature island-arc affinity (Khknen2005). Well-preserved primary structures indicat-ing a subaerial or shallow-water depositional envi-ronment are common (Kousa & Lundqvist 2000).Te sedimentary rocks are characterized by sand-stones, conglomerates and silty mudrocks with

volcanic provenance. Te composition o intrusive

rocks mainly varies rom quartz diorite to granite,but gabbroic intrusions and intermediate to mafichypabyssal rocks also occur in the area. Regional

metamorphism in the area culminated in amphi-bolite acies conditions, and later retrograde meta-morphism caused the alteration o andalusite intosericite and quartz (Vsti 1989).

Te stratiorm Rauhala massive sulphide depositis hosted by a metasedimentary sequence consist-

ing o metaturbidites and mica schists with blackschist, quartz-eldspar schist, cordierite gneissand tuffitic hornblende schist interlayers (Figs 5and 6). Locally well-preserved graded beddingstructures indicate that the metasediments areacing upwards. Te metasediments are intrudedby a subvolcanic quartz diorite and thin conorm-able tholeiitic uralite porphyrite dykes, which areyounger than the ore deposit (Vsti 1989). Tedeposit occurs as a thin concordant sheet in themetasedimentary host rocks. Te olded outcrop

can be traced at the surace or about 650 m. Teorebody consists o two parts (Fig. 6). Te westernmain orebody, which contains most o the massivesulphides, is gently olded with a old axis dippingat 25 to the northeast. Te small eastern orebodyis only intersected by one drill hole. Te depositcontinues down to the depth o 190 m, where itis only a ew tens o centimetres thick. Te maxi-mum dimensions o the main orebody are 590 mrom east to west and 350 m rom north to south.Te thickness o the orebody varies rom 0.2 m to

5.9 m, with an average o 2.1 m (Vsti 1989). Tedeposit consists o massive and disseminated ores.Te massive ore orms a 0.203.75-m-thick con-tinuous sheet having an average thickness o 1.35m. Te disseminated ore has an average thicknesso 0.75 m, and it mostly occurs in sericite schist be-low the massive orebody. A narrow zone o net- orbreccia-textured sulphides occasionally occurs inthe lower part o the massive orebody.

Te main ore minerals are pyrrhotite, sphaler-ite, chalcopyrite, galena and pyrite. Accessory oreminerals include arsenopyrite, marcasite, tetrahe-drite, boulangerite, stannite, kesterite, electrum,Au-Ag amalgam, native bismuth, cassiterite andrutile (Kojonen et al. 1989). Pyrrhotite is the pre-dominant iron sulphide mineral in the orebody,but pyrite and marcasite prevail along the westernand southern margins o the orebody. Hematiteand ilmenite occasionally occur in the dissemi-nated ore, and bornite, chalcocite, covelline andnative copper occur together with marcasite and

goethite in the weathered margin o the orebody.Quartz, muscovite, iron-bearing serpentine andchlorite occur as gangue minerals in the massive


17/394

16


ore area (Kojonen et al. 1989). Te average chemi-cal composition o the Rauhala deposit is 1.33 %Cu, 4.79 % Zn, 0.96 % Pb, 0.4 g/t Au and 53 g/t Ag(Appendix 2, able 1).

Although the contents o all the ore metals arehighest in the massive orebody, average relative

concentrations reveal a vertical zonation, in whichcopper and arsenic are concentrated in the oot-wall mineralised rocks, zinc in the massive ore,and lead in the hanging-wall mineralised rocks(Rasilainen & Vsti 1989). Te massive orebodyalso shows semiconcentric lateral zonation, (arse-nic, gold) - copper - zinc - (lead, silver, antimony),

Mafic volcanic rock

Quartz-feldspar schist

Metaturbidite, mica schist

Intermediate hypabyssal rock

Uralite porphyrite

Plagioclase porphyrite

Gabbro

Granite

Granodiorite

Quartz diorite

0 1 2 km

N

rom the southwestern part towards the northeast.Hydrothermal alteration o the mica schists,

presumably related to mineralisation, is maniest-ed by sericitisation and silicification o the ootwallrocks o the massive sulphide orebody at a distanceo 0.58 m. Much weaker alteration o the hang-

ing-wall rocks is seen as localized sericitisation.Te characteristics o the sulphide orebody, thealteration eatures and the geochemical zonationo the ore metals are considered to be consistentwith the interpretation that the Rauhala deposit isa massive sulphide deposit occurring in its prima-ry location and position (Rasilainen & Vsti 1989).

Fig. 5. Simplified geology around the Rauhala deposit. Te rectangle indicates the area o Fig. 6. Map based on GeologicalSurvey o Finland (2010a).


18/394

17



W E

0 100 200 m

NA

0 25 50 m

B

W E

Massive ore Mica schist

Andalusite

Quartz dioriteSericite schist

Black schist

Muscovite

Uralite porphyrite

Disseminated ore Metaturbidite

Subsurface extensionof massive ore

Glacial drift

2.1.3 Mafic type: Te Hllinmki deposit

Tere are three well-known mafic VMS depositsin Finland (see Appendix 2, able 1), and Hllin-mki is the only one o these to have been mined.Te deposit is located in southeastern Finland, 45km north-northeast o the city o Mikkeli (Fig. 2).

Te Hllinmki deposit was discovered in 1964afer intensive exploration prompted by severallayman samples rom the area. Open pit miningo the deposit in the Virtasalmi mine started in1966 and underground mining was carried out in19721983. Te mine was closed in 1984 due tothe exhaustion o resources. Cumulative produc-

Fig. 6. Plan (A) and vertical (B) sections o the Rauhala deposit. Modified rom Vsti (1989).


19/394

18


tion was 4.2 Mt o ore containing 32,000 t o cop-per (Puustinen 2003). Te Hllinmki deposit andits surroundings have been described by Kahma(1965), Hyvrinen (1966, 1969), Siikarla (1967),Vaajoensuu et al. (1978), Pulkkinen (1985), Lawrie(1987, 1992) and Pekkarinen (2002).

Te Virtasalmi area is located at the southernend o the Savo belt (Khknen 2005). Te area ischaracterised by mafic volcanic rocks o the Vir-tasalmi suite, mica gneisses o the Hme migma-tite suite and granodiorites, quartz diorites andgabbros o the Southern Finland plutonic suite(Geological Survey o Finland 2010a). Graphite-bearing schists, sedimentary carbonate rocks, calc-silicate rocks, cherts, iron-rich strata, uranium-phosphorus-bearing horizons and minor elsic

volcanic rocks occur within the mafic volcanic

rocks and mica gneisses (Lawrie 1992, Reinikai-nen 2001, Pekkarinen 2002). Several copper oc-currences, in addition to the Hllinmki deposit,are located in the area. Te mafic volcanic rocks aresubalkaline, mainly medium-K, tholeiitic basaltsand andesites, which probably erupted 1.921.905Ga ago in relatively shallow water, possibly in arif-related or marginal basin setting (Lawrie 1992,Korsman et al. 1997, Pekkarinen 2002, Khknen2005). Te mafic volcanic rocks in the Hllinmkideposit area are intruded by diorites and tonalities,

as well as minor leucogabbros, mafic dykes andpegmatites (Fig. 7).

Te Hllinmki deposit is enclosed in mafic vol-canic rocks (amphibolites) with a probably pyro-clastic origin (Lawrie 1987) at the contact o a dior-itic plutonic rock to the southwest. Te immediatewall rocks o the orebody are garnet (andradite)skarns and diopside-bearing mafic volcanic rocks.Te andradite skarns occur as irregular lenses orcommonly boudinaged interlayers. Te main min-erals are usually andradite and hedenbergite, butin places epidote, plagioclase, scapolite, chalcopy-

rite, cubanite, pyrrhotite and magnetite also occuras major minerals. Accessory minerals includesphene, apatite, carbonate, quartz, hornblende andpyrite. Te diopside-bearing mafic volcanic rocksare usually banded with light green bands rich indiopside and plagioclase, and dark green bands

dominated by hornblende and plagioclase. Car-bonate, epidote, biotite, scapolite, sphene, apatite,sulphides and magnetite occur as minor minerals(Lawrie 1987, Hyvrinen 1969, Pekkarinen 2002).Te host rocks and orebody have suffered poly-phase deormation and metamorphism in amphi-bolitegranulite acies conditions (Lawrie 1987,1992, Pekkarinen 2002).

Te Hllinmki deposit consists o five ore bod-ies within a westnorthwest-trending zone 500 mlong and up to 50 m wide at the surace (Fig. 8).

Te ore bodies dip almost vertically to the north-northeast and continue down to the depth o 350 m(Vaasjoensuu et al. 1978). Te Hllimki orebod-ies contain disseminated and brecciated ore types.Disseminated ore mainly occurs as evenly distrib-uted or as poorly developed layers or bands in thediopside-bearing mafic volcanic rocks. Te mainore minerals are chalcopyrite, pyrite, pyrrhotiteand magnetite. Brecciated ore occurs chiefly with-in or adjacent to the andradite skarn rocks. Tesulphides orm a coarse-grained network struc-

ture, and the breccia ore has been interpreted torepresent a stockwork zone below the Hllinmkideposit (Lawrie 1987). Te main ore minerals arechalcopyrite, cubanite and pyrrhotite, with minoramounts o pyrite and magnetite (Hyvrinen 1969,Mikkola & Rouhunkoski 1980). Gangue mineralsin the sulphide ore include diopside, hedenbergite,andradite, plagioclase, scapolite, hornblende, ac-tinolite, epidote/zoisite, quartz and sphene (Law-rie 1987, Hyvrinen 1969). Te average chemicalcomposition o the Hllinmki deposit is 0.78 %Cu and 0.1 g/t Au (Appendix 2, able 1).


20/394

19



N

Granodiorite

Diorite

Quartz diorite

Metaturbidite, mica schist


Mafic volcanic rock

Felsic tuffaceous sandstone

Gabbro

Peridotite

Hornblende gneiss

Calc-silicate rock

0 1 2 km

Karhuniemi

Lari

Sahinjoki

Hllinmki

VMS deposit/occurrence

Fig. 7. Simplified geology around the Hllinmki deposit. Te rectangle indicates the area o Fig. 8. Map based on GeologicalSurvey o Finland (2010a).


21/394

20


0 50 100 m

N

A

B

A B

0 25 50 m

Mafic volcanic rock

Diorite and tonalite

Gabbro

Pegmatite, aplite

Carbonate rock

Copper ore

Garnet skarn

Open pit outline

1

2

Fig. 8. Plan (1) and vertical (2) sections o the Hllinmki deposit. Modified rom Pekkarinen (2002) and Vaajoensuu et al.(1978).


22/394

21



No mining has taken place in porphyry copper de-posits in Finland. Known resources in the Finnishporphyry-type deposits are 45,000 t Cu, 14 t Auand 100 t Ag (Appendix 4, able 1). A descriptivemodel or porphyry copper deposits is given in

Appendix 3 and a grade-tonnage model or Pre-cambrian deposits in Appendix 4.

2.2.1 Te Kopsa deposit

Te Kopsa deposit is described here as an exam-ple o porphyry-type deposits in Finland. Actually,the deposit has variably been classified as a Prote-rozoic porphyry copper, an orogenic gold, and anintrusive-related deposit (Pym et al. 2012). Te ev-idence or a porphyry style is largely based on thepotassic alteration and the association o copperand gold. On the other hand, the evidence or anorogenic gold type is mostly based on the associa-tion o gold with quartz veins. At present, Belve-dere geologists consider Kopsa to be an intrusive-related deposit, but no conclusive classificationcan be perormed without urther studies. Severalother prospects and occurrences in Finland havebeen interpreted to belong to the porphyry class,but because Kopsa is the best known o these, it is

described here.Te Kopsa deposit is located in the Haapajrvimunicipality, central Ostrobothnia, about 110 kmeast-southeast o the city o Kokkola (Fig. 2). Tedeposit was discovered in 1939 based on laymansamples sent to the Geological Commission oFinland (Gal 1978). Te deposit has been stud-ied in several periods since 1939 by the GeologicalCommission o Finland (1939), the North FinlandResearch Foundation (19431954), OutokumpuOy (19401941, 19641966, 19711973, 1977

1978, 19811982), the Geological Survey o Fin-land (1961, 19831985), Baltic Minerals Finland(19951999) and Belvedere Resources Ltd (2002).Te deposit has never been mined, but a positive

preliminary economic assessment was publishedin 2013 (SRK Consulting Ab 2013). A recent re-source estimate gives a total tonnage o 16.3 Mt oore containing 25,800 t o copper, 13 t o gold and36 t o silver (SRK Consulting Ab 2013). However,the historic resource estimate o Gaal & Isohanni(1979) was used in this assessment. Te geology

o the Kopsa deposit and its surroundings hasbeen described by several authors, including Gal

(1978), Gal & Isohanni (1979), Isohanni (1982),Nurmi et al. (1984), Nurmi (1985), Nikander(1986), Strauss (1999), Pym et al. (2012) and SRKConsulting (2013).

Te supracrustal rocks in the area belong to the

Pohjanmaa belt (Khknen 2005) and mostly con-sist o migmatised mica gneisses and minor inter-calated quartz-eldspar gneisses, graphite schists,mica schists and volcanic amphibolites, which lo-cally contain dolomite and skarn (Pym et al. 2012).Te Kopsa gold-copper deposit is located withinthe late orogenic Kopsa tonalite, which intrudes aturbidite sequence consisting o metagraywackes,mica schists and intermediate pyroclastic volcan-ic rocks (Fig. 9). A suite o 1.881.87 Ga igneousrocks ranging rom gabbro to granodiorite intrudethe ~1.92 Ga turbidite sequence (Pym et al. 2012,SR Consulting 2013).

Te Kopsa tonalite is grey, medium-grained andmostly isotropic and non-oliated. Within most othe Kopsa outcrop, the tonalite shows a bleachedsurace due to silicification and potassium eldsparalteration (Pym et al. 2012). A ew xenoliths odark grey, fine-grained and isotropic tonalite oc-cur within the outcrop.

A plagioclase porphyry is in a ew locations in-

tersected by drill holes within the Kopsa tonalite.Te porphyry can be over 10 m thick, and it hasa dark fine-grained matrix with plagioclase crys-tals up to 8 mm in size. Te relationship betweenthe Kopsa tonalite and the plagioclase porphyry isunclear due to the lack o outcrop observations.Mineralisation has not been observed in the pla-gioclase porphyry. On the other hand, it has onlybeen intersected outside o the main mineralisedbody (Pym et al. 2012).

Te mineralised volume o rock is approximate-

ly 700 m long along strike (approximately eastwest), 200 m wide down dip towards the south(Fig. 10), and has a maximum thickness o 50 m(Pym et al. 2012, SRK Consulting 2013). Te gold-copper mineralisation is associated with quartzand arsenopyrite veining (SRK Consulting 2013).Te mineralised material consists o compact sul-phide veins, stringers and blebs in connection withquartz veining and silicification, which orm astockwork zone in the higher-grade areas. Outsidethe main veins, fine-grained sulphide dissemina-

tion occurs in the altered host rock. Te main sul-phide minerals are arsenopyrite, chalcopyrite and

2.2 Porphyry copper deposits


23/394

22


N

0 1 2 km

Quartz diorite, some diorite Quartz feldspar schist

Andesitic volcanic rock,conglomerate intercalations

Porphyritic tonalite

Granite to granodioritewith feldspar porphyroblasts

Metaturbidite

Fault Foliation inquartz diorite

S2 in veinedgneisses

A

B

0 50 100 m

Wall rock

Overburden

Cu-Au zone

Drill hole

A B

Fig. 9. Simplified geology around the Kopsa deposit. Te approximate location o the vertical section in Fig. 10 is indicated.Modified rom Strauss (1999).

Fig. 10. Vertical section o the Kopsa deposit showing the zone o combined copper and gold mineralisation. Modified romSRK consulting (2013).


24/394

23



pyrrhotite (Pym et al. 2012). Lllingite and pyriteoccasionally occur as main minerals, and minorsulphides and oxides include stannite, bornite,ilmenite, rutile, and occasionally hydrothermalgraphite. Gold occurs as ree gold (non-reractory)

with a close association with bismuth (SRK Con-sulting 2013). Te average chemical compositiono the Kopsa deposit is 0.18 % Cu, 0.57 g/t Au and4 g/t Ag (Appendix 4, able 1).

2.3 Outokumpu-type Cu-Zn-Co deposits

All the known Finnish Outokumpu-type depositsoccur in a rather restricted area in eastern Finland.Te deposits had produced 1.2 Mt Cu and 0.33Mt Zn by the end o 2012 (able 1). Well-knownresources in the Outokumpu-type deposits were0.20 Mt Cu and 0.11 Mt Zn.

A descriptive model or Outokumpu-type Cu-Zn-Co deposits is given in Appendix 5, and a

grade-tonnage model or this deposit type is givenin Appendix 6.

2.3.1 Te Kylylahti deposit

Although the Outokumpu area has a long his-tory o mining with three exhausted deposits(Outokumpu, Luikonlahti, Vuonos), Kylylahti ispresently the only operating mine excavating anOutokumpu-type deposit. Te Kylylahti depositis located in southeastern Finland, 35 km to the

northwest o the city o Joensuu (Fig. 2). Te firstindications o mineralised rocks at Kylylahti weregiven by reconnaissance exploration diamonddrilling in 1984, and the economically most inter-esting part o the deposit was intersected in 1985(Kontinen 2005). Te mine started productionin 2012, and by the end o the year, it had pro-cessed 0.37 Mt o ore and produced 4800 t cop-per and 0.14 t gold (Altona Mining Limited 2012,2013). Te Kylylahti deposit and its surroundingshave been described, among others, by Ahokas

(1984a,b), Hakanen et al. (1986), Koistinen (1986),Huhtelin & Sotka (1994), Pekkarinen et al. (1998),Kontinen (2005), Kontinen et al. (2006), Glackenet al. (2008) and Peltonen et al. (2008). In additionto Cu-Co sulphides, there is a considerable talcpotential at Kylylahti in soapstones, which werebriefly mined during the seventies (Kontinen et al.2006).

Te Outokumpu mining camp is located withinthe North Karelia Schist Belt in eastern Finland.Te schist belt rests on a late Archaean gneissgranitoid basement, east o the suture zone be-tween the Archaean Karelian Craton and the 1.93

1.80 Ga Palaeoproterozoic Svecoennian islandarc complex. Te dominantly metasedimentaryrocks o the North Karelia Schist Belt consist oautochthonous 2.52.0 Ga shallow-water deposits(mainly quartzitic sands) resting discordantly onthe Archaean basement, and younger,


25/394

24


Te ultramafic body at Kylylahti mostly con-sists o metaserpentinite altered by metamorphichydrothermal processes to talc-carbonate rockalong the margins (Fig. 11). Basaltic dykes andgabbro stocks intruding the serpentinite orm510 volume per cent o the whole ultramafic body.

Sodium-rich quartz-plagioclase rocks resemblingoceanic plagiogranites occur associated with met-agabbros at the western margin o the massi.

Te purest carbonate rocks are grey, massive andmediumcoarse-grained, and they have a massiveor irregularly banded (tremolite) structure. Temain minerals are calcite dolomite; tremoliteusually also occurs as a main component. remo-lite skarns, consisting o tremolite, dolomite cal-cite and quartz, are typically nematoblastic, schis-tose rocks that occur as irregular layers between

carbonate and quartz rocks or as thin layers andbands in the quartz rocks. However, a significantpart o the skarn material within the mineralisedzone at the eastern contact o the Kylylahti mas-si occurs as veins and breccia-type networks omassive carbonate-tremolite skarn. Tese cut andreplace the carbonate and quartz rocks as well asthe more normal skarn rocks, and host most othe disseminated copper-cobalt-zinc sulphides atKylylahti. Te purest quartz rocks at Kylylahti aredark to pale grey, fine-grained, schistose and al-

most monomineralic. Tey resemble quartzite ormetachert but are alteration products o ultramaficrocks. Varying amounts o tremolite carbonateare always present, and there is a gradation be-tween quartz rock and tremolite skarn.

Te mica schists at Kylylahti are mediumfine-grained biotite-quartz-plagioclase schists withlocally preserved primary sedimentary eatures.Te black schists are usually fine-grained, schis-tose rocks heavily stained by fine-grained graphitedust. Quartz, plagioclase, biotite and some mus-covite occur as the main silicate minerals. Temain sulphide mineral is pyrite, and the pyritecontent o the black schists can be very high, upto 50 volume per cent. Pyrrhotite occurs in vari-able amounts, and sphalerite and chalcopyrite areminor components. Tin (


26/394

25



0 0.5 1 km

Sulphide ore

Serpentinite

Black schist

Mica schist

Quartz rock

Carbonate-skarn rock

Talc-carbonate rock

A B

Fig. 11. Simplified geology around the Kylylahti deposit. Te location o the vertical section in Fig. 12 is indicated. Map basedon Geological Survey o Finland (2010a) and Kontinen et al. (2006).


27/394

26


Mica schist

Black schist

Calc-silicate and quartz rock

Serpentinite

Carbonate and calc-silicate rock

Talc-carbonate rock

Massivesemimassive sulphides

0 50 100 m

>1000 ppm Cu

Fault

Diamond drill hole

A B

Fig. 12. Vertical section o the Kylylahti deposit. Modified rom Kontinen et al. (2006).


28/394

27



3 HE HREEPAR QUANIAIVE RESOURCE ASSESSMEN MEHOD

Numerous methods have been developed and ap-plied to the estimation o undiscovered mineralresources during the past decades, but the task stillremains challenging and there are no universallyaccepted, definitive procedures (e.g., Lisitsin et al.2007 and reerences therein). Te procedure weselected is based on a three-part quantitative as-sessment method developed at the USGS startingrom the mid-1970s (Singer 1975, Cox & Singer1986, Root et al. 1992, Harris et al. 1993, Singer1993, Barton et al. 1995, Drew 1997, Singer & Men-zie 2010) and increasingly used by the USGS andothers since 1975 (e.g., Richter et al. 1975, Singer &Overshine 1979, Drew et al. 1984, Bliss 1989, Brewet al. 1992, Box et al. 1996, U.S. Geological Sur-

vey National Mineral Resource Assessment eam2000, Kilby 2004, Lisitsin et al. 2007, Cunninghamet al. 2008, Hammarstrom et al. 2010, Mihalaskyet al. 2011, Rasilainen et al. 2010a, 2012, Box et al.2012, Ludington et al. 2012a,b, Hammarstrom etal. 2013, Sutphin et al. 2013, Zientek et al. 2014).

Te method was considered well suited to accom-plishing the goal o the GK assessment projectto estimate the undiscovered mineral endowmentin Finland. Te assessment is based on statisticalmethods o data analysis and integration and ittreats and expresses uncertainty. Te method ena-bles the use o varying amounts o objective geo-logical data and subjective expert knowledge, andit generates reproducible assessment results.

Te three-part method consists o the ollowingcomponents: (1) evaluation and selection or con-struction o descriptive models and grade-tonnagemodels or the deposit types under consideration,(2) delineation o areas according to the types odeposits permitted by the geology (permissive

tracts), and (3) estimation o the number o undis-covered deposits o each deposit type within thepermissive tracts. Te estimated number o depos-its is combined with the grade and tonnage distri-butions rom the deposit models to assess the totalundiscovered metal endowment.

3.1 Deposit models

Deposit models designed or quantitative assess-ments are the cornerstone o the method. Tey are

used to classiy mineralised and barren environ-ments, as well as types o known deposits, and todiscriminate mineral deposits rom mineral oc-currences (Singer & Berger 2007). Deposit mod-els that can be used in the three-part assessmentmethod include descriptive models, grade-ton-nage models, deposit density models, economicmodels and quantitative descriptive models. De-scriptive models and grade-tonnage models arean essential component o the three-part methodand they are used in all GK assessments. Deposit

density models, when available, can be used in theestimation o the number o undiscovered depos-its or an area. Economic models and quantitativedescriptive models have not been used in the GKassessment project.

3.1.1 Descriptive models

A descriptive model consists o systematically ar-ranged inormation describing all o the essentialcharacteristics o a class o mineral deposits (Bar-ton 1993). A descriptive model usually consists otwo parts. Te first part describes the geological

environments in which the deposits occur. It con-tains inormation on avourable host rocks, possi-

ble source rocks, age ranges o mineralisation, thedepositional environment, tectonic setting, andassociated deposit types. Tis part o the descrip-tive model plays a crucial role in the delineationo permissive tracts, i.e., areas where the geologypermits the occurrence o deposits o the type un-der consideration.

Te second part o a descriptive model liststhe essential identiying characteristics by whicha given deposit type might be recognized. Teseinclude ore textures and structures, mineralogy,

alteration, and geochemical and geophysical sig-natures. Te second part o the model is used toclassiy known deposits and occurrences. Identiy-ing the types o known deposits is important orthe tract delineation process, and it can sometimeshelp to delineate geological environments not in-dicated on geological maps.

3.1.2 Grade-tonnage models

A grade-tonnage model consists o data on aver-age metal grades and the associated total tonnageo well-studied and completely delineated deposits


29/394

28


o a certain type (Singer 1993, Singer & Men-zie 2010). Te total tonnage combines total pastproduction and current resources (including re-serves) at the lowest possible cut-off grade. Grade-tonnage models are usually presented as requencydistributions o tonnage and average metal grades.

Tese distributions are used as models or gradesand tonnages o undiscovered deposits o the sametype in geologically similar settings. Tey also helpin differentiating between a deposit and a mineraloccurrence, and in judging whether a deposit orgroup o deposits belongs to the type representedby the model.

It is very important to use the same samplingunit criteria or all deposits in the grade-tonnagemodel. Mixing old production data rom somedeposits with resource data rom other deposits isamong the most common errors in the construc-tion o grade-tonnage models and will produce

biased models (Singer & Berger 2007). Spatialaspects o the sampling unit must also be con-sidered. A spatial rule identiying the minimumdistance between two separate deposits o a giventype should be defined and deposits closer to eachother than the minimum distance should be com-bined in the grade-tonnage model.

3.2 Permissive tracts

A permissive tract is an area within which the ge-

ology permits the existence o mineral deposits othe type under consideration (Singer 1993, Singer& Menzie 2010). It is important to distinguish be-tween areas avourable or the existence o depos-its and permissive tracts: the ormer are a subset othe latter. Te existence o a permissive tract in anarea does not indicate any avourability or the oc-currence o deposits within the area; neither has itanything to do with the likelihood o discovery oexisting undiscovered deposits in the area.

In the three-part assessment method, permis-sive tracts should be based on criteria derivedrom descriptive models. ract boundaries should

be defined so that the likelihood o deposits occur-

ring outside o the tract is negligible. Te bounda-ries o the tracts are first defined based on mappedor inerred geology. racts may or may not containknown deposits. Te existence o deposits is usedto confirm and extend the tracts, but the lack oknown deposits is not a reason to exclude any parto a permissive area rom the tract. Original tractboundaries should only be reduced where it canbe firmly demonstrated that a deposit type couldnot exist. Tis evidence could be based on geol-ogy, knowledge o unsuccessul exploration, or thepresence o barren overburden exceeding the pre-determined delineation depth limit.

3.3 Estimation o the number o undiscovered deposits

Te third part o the three-part assessment meth-od is the estimation o the number o undiscov-ered deposits o the type(s) that may exist in thedelineated tracts (Singer 1993, Singer & Menzie2010). Te estimates represent the probability

that a certain fixed but unknown number o un-discovered deposits exist in the delineated tracts.Te estimates are carried out according to deposittype and they must be consistent with the grade-tonnage models. Tis means that, or example,about hal o the estimated undiscovered depositsshould be larger than the median tonnage given bythe grade-tonnage model and about 10 % o theestimated deposits should be larger than the upper10thquantile o the model. Te spatial rule used todefine a deposit in the grade-tonnage model must

be respected in the estimates. Well-explored andcompletely delineated deposits, or which pub-

lished grade and tonnage values exist, are con-sidered as discovered deposits, whereas depositswithout publicly available grade and tonnage in-ormation, partly delineated deposits, and knownoccurrences without reliable grade-tonnage esti-

mates are counted as undiscovered.Several methods can be used either directly

or as guidelines to make the estimates. Tese in-clude the requency o deposits in well-exploredgeologically analogous areas (deposit densitymodels), local deposit extrapolations, countingand assigning probabilities to geophysical and/orgeochemical anomalies, process constraints, rela-tive requencies o associated deposit types, andlimits set by the total available area or total knownmetal (Singer 2007). Some o these methods pro-

duce a single estimate o the expected number odeposits; others produce a probability distribution


30/394

29



o the expected number o deposits. In the lattercase, the spread o the estimates or the numbero deposits associated with high and low quantileso the probability distribution (or example, the 90% and 10 % quantiles) indicates the uncertainty othe estimate. Te expected number o deposits, or

the estimated number o deposits associated with agiven probability level, measures the likelihood othe existence o a deposit type.

Te estimates are typically made subjectively bya team o experts knowledgeable about the deposittype and the geology o the region. Te process ol-lows the Delphi technique (Chorlton et al. 2007),in which each expert makes an estimate indepen-dently and all the estimates are then discussed to

possibly reach a final consensus estimate.

3.4 Statistical evaluation

Te three parts o the assessment method de-scribed above produce consistent estimates o thenumber o undiscovered deposits or the deline-ated areas and o the probability distribution ogrades and tonnages o the deposit type (Singer &

Menzie 2010). As the final step o the assessment,

these estimates are combined using statisticalmethods to achieve probability distributions o thequantities o contained metals and ore tonnages inthe undiscovered deposits. Sofware using MonteCarlo simulation has been developed or this pur-

pose (Root et al. 1992, Duval 2012).

4 ASSESSMEN OF Cu-Zn RESOURCES IN FINLAND

4.1 Resources covered by the assessment

Tis report contains the results o the assessmento undiscovered resources o copper and zinc inVMS-type, Outokumpu-type and porphyry-type

deposits. Te other deposit types listed in Chap-ter 2 were not included either because they are

covered in other reports, they were consideredinsignificant or the copper-zinc endowment inFinland, or a grade-tonnage model could not be

constructed due to the lack o reliable data.

4.2 GK assessment process

Te assessment process started with the selectiono experts or the assessment team. As the workwas conducted as a GK internal project, onlypersons employed by GK were assigned. Sci-entists rom the northern, eastern and southernregional offices o GK were included in the as-

sessment team to ensure first-hand knowledge oall covered areas. Te work started with a two-dayworkshop on 23 February 2010, at which the par-ticipants were introduced to the three-part assess-ment method. Te types o known copper and zincdeposits in Finland and their characteristics werereviewed and deposit types to be included in theassessment were selected. Tree types o depositswere included in the assessment: VMS deposits,Outokumpu-type deposits and porphyry copperdeposits. Responsibilities or the delineation and

documentation o initial permissive tracts and orreviewing the existing grade-tonnage data or the

selected deposit types were assigned to the assess-ment team members.

Afer the workshop, the work continued withthe delineation o preliminary permissive tracts,the preparation o tract description documentsand the development o descriptive and grade-ton-

nage models or the deposit types. Grade-tonnagemodels were constructed or Finnish VMS depos-its, Outokumpu-type deposits and porphyry cop-per deposits. Te finalising o the permissive tractsand the estimation o the number o undiscovereddeposits was carried out in a series o workshopsin 20102013.

Afer the deposit models were finalised, MonteCarlo simulations were run to estimate the met-al abundances in undiscovered deposits or eachtract. Finally, the tract reports and other parts o

the present report were combined.


31/394

30


Te assessment team used geological maps in digi-tal and paper ormat, databases o mineral depos-its and occurrences, technical reports on depositsand occurrences, mining company websites, andpublished geological literature. Te personal ex-perience and knowledge o the assessment teammembers concerning the areas assessed was a val-uable addition to the publically available inorma-tion. All data used in the assessment work or anypermissive tract are listed in the respective tractdescription document in Appendix 7.

4.3.1 Geology

Te GK in-house GIS map database o Finnish

bedrock (Geological Survey o Finland 2010a)ormed the main source o lithological data or thiswork. Te multi-scale database covers the wholeo Finland and is regularly updated. A version othe database at the 1:200,000 scale can be viewedat http://en.gtk.fi/inormationservices/map_ser-

vices. Detailed maps produced by exploration andresearch campaigns by various parties were alsoavailable or many areas.

4.3.2 Known mineral deposits and occurrences

Te FINCOPPER database (Vsti 2009), the FIN-ZINC database (Eilu & Vsti 2009), the Fennos-candian Ore Deposit Database (FODD 2012) anda recent report on mineral deposits and metallo-genic belts in the Fennoscandian Shield (Eilu 2012)were the main sources o data or known zinc andcopper deposits and occurrences in Finland andthe Fennoscandian Shield. Where possible, thegrade and tonnage data were checked and updatedrom company reports and publications. Te GK

in-house GIS database o mineral occurrences inFinland was also used or inormation on knownoccurrences. Reports in GK report databases,published literature on known deposits, prospectsand occurrences, and mining company websites

4.3 Data used

were used as additional sources o inormation onFinnish deposits and occurrences. For global datarom outside o the Fennoscandian Shield, the re-cently published grade-tonnage data o Mosier etal. (2009) were used or VMS deposits and datapublished by Singer et al. (2005) and Sinclair (2007)were used or porphyry copper deposits.

4.3.3 Geophysical and geochemical data

Low-altitude airborne magnetic survey datao GK (Hautaniemi et al. 2005) covering thewhole o Finland were used in the delineation opermissive tracts. Gravimetric maps, based ondata provided by the Finnish Geodetic Institute

(Kriinen & Mkinen 1997) or on regional grav-ity measurements by GK where available (Elo2003), were also occasionally utilised. Te RockGeochemical Database o Finland (Rasilainen etal. 2007) was occasionally used to veriy rock typeswhen delineating permissive tracts. Te igneousrock age database o GK (Geological Survey oFinland 2009) was used to check the ages o rockunits.

4.3.4 Exploration history

Te location o effective and recently expiredclaims as well as claim reports rom GK data-bases (Geological Survey o Finland 2010b, 2011a,b) were used to estimate exploration activities orcopper and zinc in various areas in Finland. Inter-nal GK GIS maps o the coverage o geophysi-cal measurements, geochemical sampling, anddiamond drilling by GK as well as OutokumpuOy and other exploration companies, were used toestimate the inte

Geological Survey of Finland - Report of Investigation

Documents

Transcript of Geological Survey of Finland - Report of Investigation