GEOSCIENCE MAP 2011-4 Geology, Geochronology,...

Page 1

5570000N5590000N

624000E 640000E

640000E610000E 624000E

610000E55

7000

0N55

9000

0N

92

84

82

80

86

88

34 36 3828 32

76

78

94

74

64

66

68

72

3026

343026 28 32 36 381808 12 14 16 20 22

20 2216 1808 12 14

64

66

68

72

84

86

88

76

74

78

80

82

92

94

Tlakwa

Creek

Welch

Lakes

Tahsish

River

Lake

Tahsish

Creek

Kilpala

River

Karmutsen

Cross

Lake

Kwais

Creek

Rive

r

KeoghLake

River

Raging

Clux

ewe

Lakes

IsleLake

Iron

Lake

LacTruite

RIVER

BENSO

NThree

Creek

AnglerLake

Three

LakeMaynard

Lake

Cree

k

Benson

Newt

Lake

MerryWidow Creek

Creek

Rainier

Kauwinch

River

KathleenLake

Wad

yC

reek

Malook

Croft

Creek

Teihsum

River

Creek

Creek

Pinch

B e n s o n

Creek

R i v e r

Yootook

R i v e r

K a s h u t l

R i v e r

M a r b l e

MarbleRive

r

Sorenson

Creek

JeuneCreek

Creek

Cayus

e

How

lal

Utlu

h

Cree

k

CreekColonial

Creek Cayeghie

NequilipaalisCreek

Lipp

y

Creek

Point

Ketchen

Island

Frigon

Islets

Ker

60

7075

22

44

50

70

78

22

18

27

25

30

30

27

22

20

32

20

10

5517

29

25

16

7

15

26

32

30

32

24

45

30

27

25

35

44 30

28

64

36

34

28

33

2735

26

32

66

40

39

33

30

28

3652

45

32

42

37

23

38

37

30

3035

80

33

25

75

25

20

85

32

29

65

40

38

35

70

50

30

45

66

24

21 43

35

37

82

37

33

19

9

31

11

42

60

33

44

47

35

47

28

55

75

51

15

36

35

40

34

55

47

52

21

85

73

28

18

42

21

45

402725

15

10

31

25

36

65

18

64

10

20

28

25

30

20

30

80

19

42

3045

15

26

22

75

80

35

36

38

30

74

35

50

8530

42

43

32

48

58

30

46

52

37

21

60

35

40

67

35

40

57

68

2635

35 15

45

30

24

57

47

15

30

76

60

42

40

18

30

12

78

55

85

35

18 30

32

40

42

36

20

25

45

24

25

34

75

52

50

4220

19

38

23

23

60

6

80

13

3050

24

17

48

34

43

26

82

22

25

26

38

21

32

8 36

30

38

23

30

18

30

20

78

2210

15

40

32

30

32

20

30

54

68

24

20

28

40

20

35

21

33

35

19

50

35

20

40

40

26

32

70

28

40

11

37 40

20

16

35

18

16

35

26

80

20

65

10

25

60

60

35

65

21

80

55

80

14

75

30

1012

2435

38

5018

35

70

43

80

27

20

68

18

3337

4634

5046

39

40

80

5243

32

42

40

39

38

35

18

36

36

26

44

18

41

50

27

14

26

80

34

52

40

45

19

35

33

44

21

2465

28

50

47

40

58

48

20

7363

78

59

82

62

65

6080

64

50

42

40

60

60

3535

13

60

72

11

90

52

28

1725

50

38

26

21

3860

10

33

55

40

32

48

46

25

65

30

35

75

24

40

25

27

32

80

30

66

27

37

37

Inset Map

G. T. Nixon, K. A. Johnston,M. C. Kelman and R. D. M. Rayner

Data Compilation

MagneticDeclination

MagneticNorth

Grid

Nor

th1º 21'

Approximate mean magneticdeclination February 2011 for

centre of map area: 18 degrees22 minutes east, decreasing

annually 12.3 minutes per year

Base Map Information

Base map produced from digital TRIM (TerrainResource Inventory Management) 1:20 000-scaletopographic database, British Columbia Ministry ofNatural Resource Operations.

North American Datum 1983 (NAD83). UniversalTransverse Mercator Projection (Zone 9). Elevation inmetres above mean sea level. Contour interval 100m.

G. T. Nixon

Digital Cartography

Major Intrusions

_ _Plutonic Rocks

BasalticAndesite Andesite

Dacite-Rhyolite

>53 < 57 >57 < 63 > 63

WHOLE-ROCK GEOCHEMISTRY LEGEND

* High proportions of veinlets and/or amygdule fillings, or pervasive fine-grained alteration, commonly involving chlorite, epidote,albite, calcite, quartz, sericite, prehnite, zeolites and clay minerals, and less commonly actinolite, potassium feldspar and pumpellyite.

Severely altered *

Volcanic Rocks

ClassificationSiO wt %2

(MgO>12 wt %)Basalt

_< 53Picrite

< 53

Least altered

Alkali metasomatized

Greene, A. R., Scoates, J. S., Weis, D., Nixon, G. T. and Kieffer, B. (2009): Melting history and magmaticevolution of basalts and picrites from the accreted Wrangellia oceanic plateau, Vancouver Island,Canada; Journal of Petrology, Volume 50, pages 467-505.

Senowbari-Daryan, B. and Stanley, G. D., Jr. (2009): Taxonomic affinities and paleogeography of StromatomorphaCalifornica Smith, a distinctive Upper Triassic reef-adapted demosponge; Journal of Paleontology, Volume 83,pages 783-793.

Carruthers, A. H. and Stanley, G. D., Jr. (2008): Late Triassic silicified shallow-water corals and other marinefossils from Wrangellia and the Alexander terrane, Alaska and Vancouver Island, British Columbia; inBlodgett, R. B. and Stanley, G. D., Jr., editors, The Terrane Puzzle: New Perspectives on Paleontology andStratigraphy from the North America Cordillera; Geological Society of America Special Paper 442, pages 151-179.

Steiger, R. H. and Jäger, E. (1977): Subcommission on geochronology: convention on the use of decay constantsin geo- and cosmochronology; Earth and Planetary Science Letters, Volume 6, pages 359-362.

Muller, J. E., Northcote, K. E. and Carlisle, D. (1974): Geology and mineral deposits of Alert Bay - Cape Scottmap area, Vancouver Island, British Columbia; Geological Survey of Canada, Paper 74-8, 77 pages.

Streckeisen, A. and LeMaitre, R. W. (1979): A chemical approximation to the modal QAPF classification of theigneous rocks; Neues Jahrbuch für Mineralogie Abhandlungen, Volume 136, pages 169-206.

Ray, G. E. and Webster, I. C. L. (1991): Geology and mineral occurrences of the Merry Widow property,Vancouver Island, British Columbia; BC Ministry of Energy, Mines and Petroleum Resources, Open File1991-8, scale 1:50 000.

Muller, J. E. and Roddick, J. A. (1983): Geology, Alert Bay - Cape Scott, British Columbia; Geological Surveyof Canada, Map 1552A, scale 1:250 000.

Stanley, G. D., Jr. (1989): An Upper Triassic reefal limestone, southern Vancouver Island, British Columbia;Canadian Society of Petroleum Geologists, Memoir 13, pages 766-755.

Jeletzky, J. A. (1976): Mesozoic and ?Tertiary Rocks of Quatsino Sound, Vancouver Island, British Columbia;Geological Survey of Canada, Bulletin 242, 243 pages.

Greene, A. R., Scoates, J. S., Weis, D., Katvala, E. C., Israel, S. and Nixon, G. T. (2010): The architecture ofoceanic plateaus revealed by the volcanic stratigraphy of the accreted Wrangellia oceanic plateau; Geosphere,Volume 6, pages 47-73.

Janousek, V., Farrow, C. M. and Erban, V. (2006): Interpretation of whole-rock geochemical data in igneouspetrology: introducing Geochemical Data Toolkit (GCDkit); Journal of Petrology, Volume 47, pages 1255-1259.

Selected References

Breitsprecher, K. and Mortensen, J. K. (2004): BCAge 2004A-1: a database of isotopic age determinations forrock units from British Columbia; BC Ministry of Energy and Mines, Open File 2004-3 (Release 3.0).

Greene, A. R., Scoates, J. S., Nixon, G. T. and Weis, D. (2006): Picritic lavas and basal sills in the Karmutsenflood basalt province, northern Vancouver Island, British Columbia; in Geological Fieldwork 2005, BC Ministryof Energy, Mines and Petroleum Resources, Paper 2006-1, pages 39-51.

Scale 1:50 000

2 4

kilometres

0

Undifferentiated basaltic to rhyolitic flows and pyroclastic rocks (mainly subaerial);includes ash-flow and rare airfall tuff and reworked equivalents, minor pillow lava, pillowbreccia, hyaloclastite and rare pyroclastic surge deposits, locally intercalated with marineto non-marine volcanic conglomerate, sandstone, siltstone, mudstone, impure limestoneand debris-flow deposits

Dark grey-green, basaltic to andesitic flows with minor intercalated volcaniclastic andsedimentary lithotypes similar to unit TrJBvs; locally includes minor pillow lava/breccia;may include minor rhyolitic flows and pyroclastic rocks

Greenish to brownish grey, thinly bedded to massive sandstone, siltstone, mudstone,pebble conglomerate and minor coal; locally fossiliferous

Undifferentiated strata of the Parson Bay Formation (uTrP) and overlying volcaniclastic-sedimentary unit (TrJBvs) in the lower part of the Bonanza Group (outside the map area)

Dark to pale grey, basalt to rhyolite flows, flow domes and volcanic breccia; aphaniticto porphyritic; minor interbedded sedimentary rocks include volcanic conglomerate,sandstone, siltstone, and debris-flow deposits

Upper Valanginian to Barremian

Grey to greenish grey and brown, medium to coarse-grained arkosic to lithic wacke,pebble to cobble conglomerate, siltstone and minor coal; locally fossiliferous

Lower Jurassic (Hettangian to Upper Sinemurian)

Undifferentiated volcanic and sedimentary rocks of the Bonanza Group(outside the map area)

LE MARE LAKE VOLCANIC UNIT

UPPER TRIASSIC TO LOWER JURASSIC

LAYERED ROCKS

NANAIMO GROUP EQUIVALENTS (IN PART)

LONGARM FORMATION EQUIVALENTS

BONANZA GROUP

Campanian to ?Maastrichtian

LOWER CRETACEOUS

TERTIARYNeogeneALERT BAY VOLCANIC UNIT

UPPER CRETACEOUS

Yreka shale-limestone unit: black carbonaceous or graphitic shale passing upwardinto black to medium grey, thin to medium-bedded, variably carbonaceous, siltylimestone with shale partings, concretionary limestone, mudstone and siltstone;locally fossiliferous; may be included in unit TrJBvs where not mapped separately(or pass laterally into coarser-grained clastic deposits)

Dark grey-green basaltic flows and minor volcaniclastic breccia and lapilli tuff;aphanitic to coarsely clinopyroxene-plagioclase±olivine-phyric

Dark grey-green, basaltic volcaniclastic breccia and lapilli tuff; aphanitic tosparsely plagioclase±clinopyroxene-phyric

Pale pinkish grey, reworked, crystal-vitric rhyolitic tuff; weak internal laminations

Sutton limestone equivalent: thin (<10m) unit of pale to medium grey, massivereefoid limestone near the top of the Parson Bay Formation; contains silicifiedcorals and other fossils; likely equivalent in part to the Sutton limestone in theCowichan Lake area, southern Vancouver Island

volcaniclastic breccia and debris-flow deposits, and rare vitric tuff, pebbly sandstone andconglomerate; shale locally yields abundant thin-shelled bivalves (Halobia sp., Monotis sp.);limestone locally contains rare algal structures; may include coralline limestone (Suttonlimestone equivalent in part; see below) near the top of the succession

Medium grey to black, thinly laminated to medium bedded, impure limestone, calcareous tonon-calcareous mudstone, siltstone and shale intercalated with variable proportions of grey-green lithic feldspathic/tuffaceous wacke, minor crystal-lithic tuff and reworked equivalents,

Dark grey-green, andesitic volcaniclastic breccia and/or crystal-lithic lapilli tuff;plagioclase-rich; locally includes interbeds of dark grey, impure limestone

Dark grey-green, basaltic volcaniclastic breccia and lapilli tuff; aphanitic tocoarsely clinopyroxene-plagioclase±olivine-phyric

Dark grey-green, basaltic volcaniclastic breccia, lapilli tuff and lesser pillowedflows; aphanitic to clinopyroxene-plagioclase±olivine-phyric

Dark grey-green, andesitic volcaniclastic breccia and lapilli tuff;hornblende-clinopyroxene-plagioclase-phyric

Dark grey-green, basaltic volcaniclastic breccia, lapilli tuff and minor flows;aphanitic to coarsely clinopyroxene-plagioclase±olivine-phyric; may includeminor interbedded wacke, siltstone, mudstone and shale (locally fossiliferous)

PARSON BAY FORMATIONUpper Triassic (Carnian to Rhaetian)

Dark grey-green, basaltic to andesitic volcanic breccia of epiclastic and pyroclasticorigin, and variably reworked lithic-crystal tuff; locally includes fine-grainedsedimentary interbeds

Medium grey, rhyolitic to dacitic flows, flow domes and/or pyroclastic rocks, includingflow and pyroclastic breccias, welded to non-welded crystal-lithic lapilli tuff and rareairfall tuff; aphanitic to feldspar-phyric; may include thin interbedded sedimentarydeposits and minor basaltic to andesitic flows

Dark grey-green, plagioclase-megacrystic (0.8-2cm), variably amygdaloidal basalticto andesitic flows; locally intercalated with aphanitic and plagioclase-phyric flows;texturally similar to plagioclase-megacrystic Karmutsen basalt in unit uTruKf

Small outcrop of plagioclase-megacrystic basaltic to andesitic flows of unit lJLx;texturally similar to plagioclase-megacrystic Karmutsen basalt in unit uTruKf

Medium grey to reddish grey, rhyolite flows and minor flow and/or volcaniclasticbreccia; aphanitic and flow-laminated

Upper Triassic (Rhaetian) to possibly Lower Jurassic (Hettangian)

Interbedded volcaniclastic and sedimentary strata (predominantly submarine):buff to grey-green, thin to very thickly bedded, calcareous to non-calcareous, volcanicbreccia, lithic and feldspathic wacke, siltstone and limestone, locally coralline; lithic-crystal tuff, lapilli tuff and reworked equivalents; and minor vitric tuff, pebbly sandstone,siltstone, and volcaniclastic debris-flow deposits; may include black carbonaceousshale, mudstone, siltstone and limestone (locally coralline) equivalent to unit TrJY

VOLCANICLASTIC-SEDIMENTARY UNIT

uTrPvpmc

uTrPvmc

uTrPvfmc

lJLv

lJLm

TrJBft

uTrPvm

uTrPvia

lJLf

lJLx

TrJBf

TrJY

TrJBfmc

uTrP

uTrPvix

lJL

TrJB

TrJlB

TrJBvs

uKN

lKL

TAv

2011-3 2011-5

2011-1 2011-2

Alice Lake Area(92L/06 & part of 92L/03)

2011-4

200100

kilometres

0

USA

Vancouver

Columbia

Canada

Peninsula

British

Olympic

Victoria

Nanaimo

VancouverIsland

Campbell River

Port Alberni

Port McNeillPort Hardy

Port Alice

GEOCHRONOLOGYby

R.M. FRIEDMAN (The University of British Columbia)D.A. ARCHIBALD (Queen's University)

Geology, Geochronology, Lithogeochemistry and Metamorphismof the Alice Lake Area, Northern Vancouver Island

G.T. Nixon, L.D. Snyder, G.J. Payie, S. Long, A. Finnie, A.J. Orr, R.M. Friedman,D.A. Archibald, M.J. Orchard, E.T. Tozer, T.P. Poulton and J.W. Haggart

BC Geological Survey

GEOSCIENCE MAP 2011-4

NTS 092L/06 and part of 092L/03

GEOLOGYby

G.T. NIXON, L.D. SNYDER, G.J. PAYIE,S. LONG, A. FINNIE and A.J. ORR

(BC Geological Survey)

PALEONTOLOGYby

M.J. ORCHARD, E.T. TOZER, T.P. POULTON andJ.W. HAGGART (Geological Survey of Canada)

(K) Kerri; (M) Magnus;

(Cb) Columbianus; (C) Cordilleranus;

C Carnian; N Norian; R Rhaetian

GSC Macrofossil locality (fossil age code below)

Conodont locality (fossil age code below; identification by M. J. Orchard)

Fossil age designationT Late Triassic; J Jurassic; K Cretaceous

Macrofossil locality (fossil age code below; identification by E. T. Tozer,T. P. Poulton and J. W. Haggart)

GSC Conodont locality (fossil age code below; identification byM. J. Orchard)

S Sinemurian; P Pliensbachian;

T Toarcian

Jurassic:Late Triassic:

e early; m middle; l late

l lower(no label indicates age indeterminate;combined codes indicates age/zone range)

(S) Suessi

Ammonite Zone:

TlC(W)

TIN

TeN

TC

Lineation, inclined, horizontal (slickenfibres on steeply dipping fault)

Axial plane of minor fold, inclined

Tertiary dike, inclined, vertical

Dike, inclined, vertical

Volcanic flow lamination, inclined

Fossils

Eutaxitic foliation/welding, inclined

Outcrop too small to show at map scale

Structure

Bedding, inclined

Columnar cooling-joint orientation in sill50

Outcrop examined

30

17

14

30

70

64

17

Hornblende hornfels facies: hornblende+plagioclase±epidote±quartz

Upper greenschist facies: actinolite+chlorite+albite±epidote±quartz±calcite

Prehnite-pumpellyite facies mainly: pumpellyite±prehnite+chlorite+albite±epidote±quartz±calcite

MINFILE locality (092L 056)

Topography

Flooded land (swamp)

Stream or river

Contour (100m)

Mineralization

Road (paved)

Spot height (m)

Road (gravel)

56

Lake

Ar/ Ar date (Ma, 2 sigma error); Bi, biotite; Hb, hornblende;Ph, phlogopite (determined by D. A. Archibald)

K/Ar date (Ma, 2 sigma error); WR, Whole-rock (Breitsprecherand Mortensen, 2004)

U-Pb zircon date (Ma, 2 sigma error); Zrd, detrital zircon(determined by R. M. Friedman)

Geochronology40 39

Metamorphism

197.1 (±0.3) Zr

3.0 (±1.0) WR

172 (±0.6) Bi

Steeply dipping fault, approximate

Unconformity, approximate

Unconformity, inferred

Steeply dipping fault, defined

Geological contact, defined

Geological contact, approximate

Geological contact, inferred

MAP SYMBOLS

Steeply dipping fault, inferred

Limit of mapping

Line of vertical cross-sectionA B

Dark grey-green, closely packed, pillowed basalt flows and localized, massiveinflated flow lobes; typically aphanitic and non-amygdaloidal; may include inter-pillow or rare thin lenses of well-bedded hyaloclastite

Dark grey-green, thinly bedded to laminated hyaloclastite sandstone

Small lens of dark grey, thinly bedded to laminated hyaloclastite sandstone

Dark grey-green, massive to medium bedded, basaltic hyaloclastite breccia, includingpillow-fragment breccia, and medium bedded to laminated hyaloclastite sandstone;may locally pass laterally into pillowed basalt flows

Small outcrop of dark grey-green, plagioclase-megacrystic (1-2cm) basaltflow; commonly amygdaloidal and locally exhibiting trachytoid textures;intercalated with aphanitic or plagioclase-phyric basalt near the top ofthe succession

Medium to pale grey, thinly bedded to massive micritic limestone and locallybioclastic limestone; minor silica replacement and chert nodules; rare laminatedinterbeds, oolitic layers and algal structures; locally fossiliferous

Thin (0.5-5m) beds of pale to medium grey, micritic to rarely bioclasticlimestone intercalated with basalt flows near the top of the succession

Dark grey-green, aphanitic to plagioclase-phyric and minor plagioclase-megacrysticbasalt flows, commonly amygdaloidal and locally exhibiting laminar flow features(vesicle trains) and pipe vesicles; may include minor pillow lava and hyaloclastite

Undifferentiated, dark grey-green basalt flow/hyaloclastite/pillow lava(outside the map area)

Dark grey-green, closely packed, pillowed basalt flows; aphanitic toplagioclase-phyric and rarely plagioclase megacrystic; may includeinter-pillow or thin beds of hyaloclastite

Dark grey-green, closely packed, pillowed basalt flows; aphanitic andvariably amygdaloidal

LAYERED ROCKS (cont'd)

Upper Triassic (Carnian to Lower Norian)

Upper Triassic (Carnian; possibly Middle Triassic (Ladinian) at the base)

Middle Karmutsen Formation: Hyaloclastite Member

Lower Karmutsen Formation: Pillow Member

Upper Karmutsen Formation: Flow Member

KARMUTSEN FORMATION

VANCOUVER GROUP

QUATSINO FORMATION

UPPER TRIASSIC

uTruKp

uTrmKp

uTrmKh

uTrlKp

uTrlKh

uTrQ

uTrK

uTruKf

Nixon, G. T., Snyder, L. D., Payie, G. J., Long, S., Finnie, A., Orr, A. J., Friedman, R. M.,Archibald, D. A., Orchard, M. J., Tozer, E. T., Poulton, T. P. and Haggart, J. W. (2011):Geology, geochronology, lithogeochemistry and metamorphism of the Alice Lakearea, northern Vancouver Island; BC Ministry of Energy and Mines, GeoscienceMap 2011-4, 1:50 000 scale.

Recommended Citation

Small intrusion of dark grey-green, olivine-clinopyroxene-plagioclaseporphyry, locally clinopyroxene-megacrystic: coeval with mineralogicallysimilar lavas in the lower part of the Bonanza Group (units TrJBfmc/uTrPvmc/uTrPvfmc/uTrPvpmc)

Dark grey-green, clinopyroxene-plagioclase±olivine±hornblende porphyry;coeval with mineralogically similar lavas in the lower part of the BonanzaGroup (units TrJBfmc/uTrPvmc/uTrPvfmc/uTrPvpmc/uTrPvia)

Medium-grained, equigranular, hornblende±biotite quartzdiorite/monzodiorite to granodiorite (qdi-gd) phase of theMerry Widow Pluton

Dark grey-green to pale pinkish grey, medium to coarse-grained,equigranular granitoid rocks and porphyry; includes gabbro (gb),hornblende±biotite-bearing diorite (di), quartz diorite (qdi),granodiorite (gd) and hornblende-plagioclase±biotite porphyry (po);combined codes indicate a range of common rock types (gb-qdi,gabbro - quartz diorite)

Medium-grained, equigranular, hornblende quartz monzodiorite(qmd) and plagioclase±hornblende porphyry phase of VictoriaLake Pluton

ISLAND PLUTONIC SUITEEARLY TO MIDDLE JURASSIC (ca. 200.6 to 174.3 Ma)

Dark grey-green, basalt-andesite intrusion or diabase;coeval with Bonanza Group volcanism

Dark grey-green, plagioclase-megacrystic basalt-basaltic andesiteintrusion or diabase; coeval with similar lavas of the Early JurassicLe Mare Lake volcanic unit (lJLx)

Thin dike/sill of plagioclase-megacrystic basalt-basaltic andesiteor diabase; coeval with similar lavas of the Early JurassicLe Mare Lake volcanic unit (lJLx)

INTRUSIVE ROCKS

Medium to pale greenish grey, medium-grained, equigranular,hornblende±biotite granodiorite (gd) and plagioclase±hornblendeporphyry (po)

TERTIARY

Dark grey, sparsely plagioclase-phyric dacite dike

KLASKISH PLUTONIC SUITETERTIARY (EARLY PLIOCENE; ca. 5.15 to 4.6 Ma)

LATE TRIASSIC TO EARLY JURASSIC

Minor Intrusions

JIqdi-gd

MPKgd-po

MPKqmd-po

TrJBim

TrJBipoc

Tif

lJLix

JI

Benson Lake

LakeNewt

35

21

37

24

82

37

9

45

42

33

19

73

31

60

28

25

31

11

42

21

42

36

22

85

30

19

2

MERRY WIDOW Cu-Fe-Au SKARN CAMP

1

kilometres

0

40 39

Notes

All isotopic dates are calculated using the decay constantsrecommended by Steiger and Jäger (1977); recent estimatesof K decay constants would increase the Ar/ Ar age byca. 1%.

Geology in remote areas and outside the limit of mapping wascompiled from BC Assessment Reports and Muller and Roddick(1983).

CIPW (wt %) normative compositions projected in QAP: Q (qz), A (Or) and P (Ab+An) taking Fe2O3 as 0.15FeOt (total Fe as FeO). Nomenclature of plutonicrocks on the map is based on the IUGS modal QAP mineralogical classification. Any discrepancy between modal and CIPW rock nomenclature is due inpart to the projection scheme. The CIPW projection of least altered plutonic rocks (n=107; grey/black dots) yields an overabundance of Or in the norm dueto the presence of K-bearing mafic hydrous minerals (biotite, hornblende) relative to the mesonorm (red crosses); the latter produces a bias towards tonalitein the granitoid rocks (not a common rock type) whereas the CIPW projection shows bias towards quartz monzodiorite (much less common than quartz diorite).

Acknowledgments

We sincerely appreciate the warm hospitality shown to us bythe residents of northern Vancouver Island. We thank MargaretHanuse and Dave Ross for accommodations in Port McNeilland Holberg, respectively. John Fleming, BHP-Utah Mines Ltd.,kindly granted access to maps, drill logs and core from the IslandCopper Mine and other properties. Western Forest Products Inc.provided maps and digital files of logging roads in the area.Critical reviews by L. J. Diakow, N. W. D. Massey, J. L. Nelsonand P. Schiarizza greatly improved the final cartographic product.Sadly, one of our co-authors, Dr. E. T. Tozer of the GeologicalSurvey of Canada, passed away recently; his contributions toinvertebrate palaeontology will be sorely missed.

NeroutsosInlet Pluton

A

Merry WidowMountain Pluton

KilpalaRiver Pluton

P

Q

A

gd

di/gb

qdi/qgb

md/mg

tn

qmd/qmg

ag, alkali-feldspar granite; g, granite; gd, granodiorite; tn, tonalite; aqs,alkali-feldspar qz syenite; qs, qz syenite; qm, qz monzonite; qmd/qmg,qz monzodiorite/qz monzo-gabbro; qdi/qgb, qz diorite/qz gabbro; as,alkali-feldspar syenite; sy, syenite; mz, monzonite; md/mg, monzodiorite/monzogabbro; di/gb, diorite/gabbro

IUGSClassification

60

mz

qm

ag

qsaqs

20

g

syas

5P

Mesonormvs CIPW

P

Mesonormvs CIPW

VictoriaLake Pluton

A

Early PlioceneEarly Jurassic

B

-1000

0

500

A

1500metres

-500

1000

uTruKf

uTrP

uTrPvpmc

uTruKf

uTrQ

(no vertical exaggeration)

uTrQ

lKL

TAvuKN

D

0

500

1500metres

C

-500

1000

-1000

NeroutsosInlet Fault ALICE LAKE TAv

uTrlKp uTrlKpuTrlKp

TAv

uTrmKhuTruKf

JIdi

uTruKfuTrQuTrQ

uTruKfuTruKf

MPKgd-po

TAv

uTrPuTrQ

uTrP?

uTrP?

(no vertical exaggeration)

uTrPvfmc

F

500

Emetres

0

-500

1000

1500

-1000

Three LakesCreek FaultKATHLEEN LAKE

uTrlKp

uTrmKp

uTrmKhuTrmKh

uTruKfuTruKf

uTrmKh?

uTrlKp

uTrmKh? uTrlKp?

uTruKf

lJLm

uTrQ

(no vertical exaggeration)

TrJBvs

uTrP

lJLm

-1000

HGmetres

500

0

-500

1000

1500Kwais Creek

Fault

uTruKfuTruKf

uTrQ

uTrQ

uTrPvmc

uTrPlJLx

lJLm

(no vertical exaggeration)

lJLm

TrJBvsuTrP

TrJBvs