geology of vancouver island

8/12/2019 Geology of Vancouver Island

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GEOLOGICAL ASSOCIATION OF CANADA

MINERALOGICAL ASSOCIATION OF CANADA

JOINT ANNUAL MEETING 1977

VANCOUVER B.C.

FIELD TRIP 7: GUIDEBOOK

GEOLOGY OF VANCOUVER ISLAND

APRIL 21 - 24

1 1LEADERS: J.E. MULLER C.J. YORATH

GUIDEBOOK BY J.E. MULLER

1 Geological Survey of Canada100 West Pender Stree t Vancouver B.C.


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PREF CE

This guide book has been prepared for the geological f ield

t r ip on Vancouver Island, preceding the Annual Meeting, Vancouver1977 of the Geological Association of Canada. t consists of two

parts.

The f i r s t par t , a f t e r a br ie f his tor ica l in t roduct ion,

summarizes what is known about Vancouver Is land geology. t is

essent ia l ly the same as marginal notes for a 1:250,000 geological

uncoloured) map that is in preparation and hopefully will be

available for distr ibution with the guide book.

The second part is a road log for four days of geological

sightseeing by motorcoach. The route follows paved highways and

there are a few snort walks. The overview of Vancouver Is land

geology is therefore s l igh t ly unbalanced. The important Bonanza

Group is , except for some outcrops of Bonanza-like l i thology of

dubious age, not exposed on any accessible road in the south half

of the island. Upper Jurassic and Lower Cretaceous shelf sediments

are l ikewise exposed only on northern Vancouver Island. The routes.

afford a variety of the is land 1 s landscapes, even though the

beautiful f iords of the west coast are not included.


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Part I

General Geology of Vancouver Island

INTRODUCTION

Vancouver Island, the la rges t is land in the eastern Pacific

Ocean, is 45 km 280 miles) long, a maximum of 26 km 78 miles)

wide, and occupies an area of 32,137 km 12,408 square miles) . Most

of i t s area is occupied by the Island Mountains with peaks of 1,000

to 2,000 m 3,000 to 6,000 foot) e leva t ion . Many central valleys

are occupied by f inger lakes and the west coast is incised bynumerous fiords. The middle par t of the eas t coast , facing St ra i t

of Georgia, is occupied by the Nanaimo Lowlands.

The original inhabi tants of the is land were Indians of

the Wakashan language group who, today, are represented by the Nootka

and Salishan t r ibes , numbering about 7,000 in a to ta l population of

430,000.

The Spanish explorer Perez Hernandez was the i r s t white

man on record to v i s i t Nootka Sound on the west coast in 1774. James

Cook followed in 1778 during his th i rd Paci f ic voyage. Following

reports of Cook s exploration Bri t i sh t raders began to use the

harbour of Nootka Friendly Cove) as a base for a promising trade

with China in sea-ot ter pel ts but became embroiled with the Spanish

who claimed sovereignty over the Pacific Ocean. The ensuing Nootka

Incident 1790) nearly led to war between Britain and Spain but the

dispute was se t t led diplomatically. George Vancouver on his subsequent

exploration in 1792 circumnavigated the i s land and charted much of the

coast l ine . His meeting with the Spanish captain Bodega Quadra at

Nootka was friendly but did not accomplish the expected formal ceding


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of land by the Spanish to t ~ a r i t t sh . t resul ted however in his

naming the is land Vancouver and Quadra The Spanish capta in s

name was l a t e r dropped and given to the is land on the eas t side of

Discovery St ra i t .

Early sett lement of the is land was carr ied out mainly under

sponsorship of the Hudson's Bay Company whose lease from the Crown

amounted to 7 sh i l l ings per year. Victoria was founded as Fort

Victor ia by tha t company's chief factor James Douglas in 1843. The

existence of th is sett lement on the south t ip of the is land and south

of the 49th para l le l aided Bri t ish negotiators to re ta in al l of the

island when that l ine was made the northern boundary of the UnitedStates by the Oregon Boundary Treaty of 1846. The is land became a

separate Bri t i sh colony in 1858. Bri t i sh Columbia, exclusive of the

is land, was made a colony in 1858 and in 1866 the two colonies were

joined into one, to become a province of Canada in 1871 with Victoria

as capita l .

Mining of coal and l a t e r of gold, iron and copper ore have

been important indust r ies of the i s land, but in the twentieth century

industries associated with logging have become dominant. In addition

tourism, f ishing and farming are important contributors to the economy.

REGIONAL GEOLOGY

Introduction. The geology of Vancouver Is land has been explored

mainly by government geologists . Important contribut ions were made

by the following (years of fieldwork in brackets): J . Richardson

(1872-1876), G M Dawson (1887), C.H. Clapp (1909-1913), H.C. Gunning

(1929-1932), A.F. Buckham (1939-1948), J .L. Usher (1945-1948). J.W.

Hoadley (1947-1950) and J.A. Jeletzky (1949-1953) of the Geological

Survey of Canada and H S arg en t (1939-1940), J.S. Stevenson (1941-


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I N O E X O F G E O L O G I C L M P P I N G

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DD=IVVVV j

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V N C O U V E R I S L N O

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TERTIARY SEDIMENTS

TERTIARY INTRUSIONS

TERTIARY VOLCANICS

LATE MESOZOICSEDIMENTS

MIDDLE TERTIARY

EARLY TO MIDDLETERTIARY

EARLY TERTIARY

LATE JURASSIC TOCRETACEOUS

LEECH RIVER F OR M AT I ON JUR A- CRETACEOUS?

ISLAND INTRUSIONS

SO NAN ZA GROUP

QUAT SINO, PARSON SAYFORMATIONS

KARMUTSENFORMATION

SICKER GROUP

METAMORPHICCOMPLEXES

JURASSIC

EARLY JURASSIC

.LATE TRIASSIC

TRIASSIC

LATE PALEOZOIC

JURASSIC OR OLDER

DALERT BAY-CAPE SCOTT,92 L -1021

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(G. S.C. PAPER 7 8

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FIGURE 1


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1950), J.T. Fyles 1948-1951), G.E.P. Eastwood 1961-1962), W.J.

Jeffery 1960-1964} and K.E. Northcote 1968-1973) of the British

Columbia Department of Mines and Petroleum Resources. In addit ion

the work of D Carl is le , D.J.T. Carson, R Surdam and R W Yale in

the period 1960 to 1970 deserves special mention. The work of all

these geologis ts and that of the author since 1963 has been compiled

into a 1:250,000 map see also Figure 1 ) . The compiler especia l ly

acknowledges the inval iable col laborat ion in f i e ld and off ice of the

following colleages: B.E.B. Cameron, D Car l i s le , D.J.T. Carson,

W G Jeffery, J.A. Jeletzky, and K.E. Northcote. Fundamental to

the work was also isotopic dating by R.K. Wanless and paleontological

dating by B.E.B. Cameron, C.A. Ross, H Frebold, J.A. Jeletzky and

E.T. Tozer.The is land is the main component of the Insular Bel t , the

westernmost major tectonic subdivision of the Canadian Cordi l lera .

Narrow s t r ips of land on the west and south coast are newly discovered

fragments of the Pacific Belt that is well developed in the western

United States and Alaska Figures 2, 3}. The Insular Belt Island

Mountains) contains middle Paleozoic and Jurassic volcanic-plutonic

complexes, both apparently underlain by gneiss-migmatite terranes

and overlain respect ively by Permo-Pennsylvanian and Cretaceous

clast ic sediments. A thick shie ld of Upper Triassic basa l t , overlain

by carbonate-clast ic sediments, separates these two complexes in

space and time. Post orogenic Ter t iary c las t ic sediments f r inge

the west coast.

The Pacific Belt on the western and southern rim of the

island contains in t s inner eastern) par t an assemblage of Late

Jurassic to Cretaceous slope and trench deposi ts , deformed to melange

and sch is t , and an outer part of Eocene oceanic basal t and subjacent


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wfiGURE 3 TECTONIC BELTS OF CANADIAN CORDILLERA

Belts I 3 4 from Monger, Souther. Gabrielse 1972

INSULAR

rect

Clastic Sediment. .

ovement.

OMINECACRYST BELT

E

ROCKY MTNS.BELT

~ : C : ; ; ; - 1 : : 7 c ; 7 : J - - - - -

FORE DEEP


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basic crys ta l l ine rocks.

The following sections brief ly descr ibe the l i thology,

origin and s t ruc tura l re la t ions of the formations of Vancouver Island

see also Figures 4 5).

Wark and Colguitz Gneiss. The names Wark and Colquitz were applied

by Clapp 1913) to the mafic and s i l i c parts of the gneiss complex

exposed in and near the ci ty o1 Victoria . The Wark Gneiss consists

of fine to medium crys ta l l ine , massive to gneissic biotite-hornblende

dior i te and quartz diori te . Colquitz Gneiss is l igh te r coloured,

commonly well fo l ia ted biot i te-hornblende quartz diori te to grano

dior i te gneiss . Wark and Colquitz gneisses are in places int imately

i n t e r l a y ~ r e dbut i t is possible to map d is t inc t bel ts where one or

the other predominates. The l igh t coloured gneisses are believed

to have been derived from c las t i c sediments, whereas the d i o r i t i c

rocks are recrys ta l l ized basa l t ic s i l l s or flows. One zircon age

determination from Colquitz Gneiss has yielded discordant ages between

295 and 384 Ma possibly suggesting ear ly Paleozoic source rocks. K-

Argon ages on metamorphic hornblende from Wark dior i te are 163 and

82 Ma indicat ing early Jurassic metamorphism of the Paleozoic

parent rock tha t was perhaps part of the Sicker Group. o stra t igraphic

contacts with other formations have been found, but volcanic rocks,

ten ta t ive ly correlated with Jurassic Bonanza volcanics may overl ie

them unconformably.

Sicker Group. The Sicker Group comprises al l known Paleozoic rocks

of Vancouver Is land and is subdivided into a lower volcanic formation,

a middle greywacke-argill i te formation, and an upper limestone

formation. The group is exposed in narrow, fault-bounded upl i f t s .

The l a rges t . Horne Lake-Cowichan Lake upl i f t , is the southernmost,


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FIGURE4 T BLE OF FORM TIONS OF V NCOUVER ISL NDSEQUENTI L LAYERED ROCKS CRYSTALLINEROCKS COMPLEXESOFPOORLYDEFINEDAGE

.. ~ S Y M ' - I A V ~ - - SYM- i i i n r N > I i - - A i ' ~PER'-"' STAGE GROUP FORMATION DOL 1 \ \ t Q < ~ LITHOLOGY NAME DOL b u K/Ar liTHOLOGY

U late TertvolcsofPortMcNeill Tvs. . ~ ~ ~ 10 SOOKE BAY jnl>Tsa conglomerate, sandstone, shale~ WCENE to CARMANAH eoTc l :wo sandstone, silt. one, coglomerate . 1 d' .1 1 dh' .1Z ~ - s i l i c i c ~ 32-59 : N a7M g t ; ' p o r { . C ~ r yJemt e,

OLIGOCENE ESCALANTE eT E 300 conglomerate, sandstone SOOKE INTRUSIONSb . Tgb 31 49 bb th 1 1 1w b- - - - - .. - a S K : ~ . : : : . . - go ro.anor ost e,agma 1 eU earlyEOCENE MfTCHOSIN elM 3,000 basaltic lava,pillow lava.breccia, tuff M E T C H O S I N S O i i S T . G N E l ~_ ~ 47 hloril e schist.Qneiuic amphibolite

GABRIOLA K 350 nd I 1 LEECH RIVER FM. '\. , JKt JD-41 J?hy.l\ite,mjca schist.greywacke.l STRK:Hl'IA ' u GA sa stone, cong omera e 1 argtl 1te,chertVVU" J I

SPRAY uKs 200 shale, siltstone 1GEOFFREY uKG 150 conglomerate, sandstone 1

NORTHUMBERLAND uKN 250 siltstone,shale, sandstone 1I

~ ~ A M P A N I A NNANAIMO DECOURCY uKoc 350 conglomerate, sandstone 1

-< CEDAR DISTRICT uKco 300 shole.siltslone,sandstone 1~ I

EXTENSION.. PROTECTION uKEP 300 conglomerate,sandslone,shale, coal 1 1

U HASLAM uKH 200 shale,siltslone,sandstone 1- ~ N T O N I A N . . 1O COMOX uKc 350 sandstone,conglomerale,shale,coal 1

~ . IIN ALBIAN QUEEN Conglomerate Unit IKQc 900 conglomerate, greywacke 1

0 ~ APTIAN? CHARLOTTE Siltstone Shale Unit IKQp 50 silts tone, shJ90 l l / 3 . ~ 8 q ' J > c f i \ ' f ~ 8 ~ ~ C f ~ u a390 ~ u a r t z f e l d s p a rlilneissA ~ ; 3 WARK DIORITE G N ~ I ~ ~_ ' _ ~ . > __ > ~ ~~ - 1 8 2 t ~ 3 [ , ? r z 1 f f . c f i f j f . ~ ~ i i


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the Suttle Lake uplif t l ies in the centre and some smaller outcrop

areas occur to the northwest in the Nimpkish region.

The volcanic rocks range from f ine grained banded tuffs

to breccias with clasts 10 em or more in size and agglomeratic lava

flows. Flows, tuffs and related dykes commonly contain phenocrysts

of ura l i t ized pyroxene and a lb i t i zed plagioclase. A few chemical

analyses indicate chemical compositions ranging from basalt to

rhyolite. Although internal structure is generally well preserved

the rocks are mostly of low greenschist chlor i te-act inol i te metamorphic

rank. Locally they are shear-folded and converted to well fol ia ted

ch lo r i t e -ac t ino l i t e schis t . The thickness i s estimated to be between

1,000 and 3,000 metres. Only one K Ar age determination on act inol i te

in ura l i te porphyry from Saltspring Island yielded an age of 308 14

a L.R. Armstrong, pers. comm. 1975}. The apparent age of metamorphism

is thus Pennsylvanian and the primary age must be ea r l i e r Pennsylvanian

or older.

The greywacke-argillite sequence occurs in graded beds afew millimetres to several centimetres thick of a rg i l l i t e and s t -

stone or in beds up to several decimetres thick of greywacke sandstone.

The greywacke locally contains lenses of det r i ta l limestone. The

formation is commonly s i l i c i f i ed and, l ike the volcanic rocks i t s

structure varies from almost f l a t lying to i soc l ina l ly folded. Total

thickness is estimated to be about 600 metres. Fusulinids and other

foraminifera obtained from the l imestones indicate a Middle

Pennsylvanian Desmoinesian) age.

The Suttle Lake Formation, youngest part of the Sicker

Group, is exposed in many places along the margins of the uplif ts

where Paleozoic rocks are overlain by the Karmutsen Formation. Vole

1969) measured a type section in the mountains west of Suttle Lake


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Fig 5 RELATIONSHIPS OF FORM TIONS O V NCOUVER ISL ND

D

(27)EOC OliG O RMANAH W

SANDSTONE.GREYWACKE

SHALE. SILTSTONE

CONGLOMERATE

+ ..

~ l i M S T O N

M I N L YINTERMEDIATETO SILICIC TUFF ANDVOLCANIC BRECCIA

[8] INTERMEDIATE TO SILICICPYROCLASTICS ANDGREENSTONE

[ l AlCAREOUS SANDSTONE. ~ { MAINlY BASALTIC fl WSSilTSTONE

+ 4 + ?

PILLOW- BRECCIA

PillOW-LAVA

SHEARFOLDED GREYWACKE.ARGILLITE. PHYLLITE

GNEISS. SCHIST

MAINlY QUARTZ r==lMONZONITE.GRANODORITE c:::J ARGILLITE. DIABASE

MAINL I QUARTZ DIORITE.GABBRO B ANGULAR UNCONFORMITY


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of 320 m 1050 feet) of interbedded crinoidal limestone and cher t .

n the basis of brachiopods and a single fusu l in id he dated the rocks

as Early Permian Wolfcamp to Leonard) but Sada and Danner 1974)

determined a Middle Pennsylvanian age on the basis of fusul inids forthe limestone at Horne Lake.

The Sicker Group formations may be a continuous succession,

but the possibi l i ty of an unconformity between the broadly folded

Butt le Lake limestone and the commonly t igh t ly folded greywacke

a r g i l l i t e sequence cannot yet be excluded. Furthermore, as parts

of i t are invaded by Devonian or older Tyee In t rusions, the group

may represent several tectonic units of which the oldest would appear

to be pre Devonian. That question remains to be solved by fur ther

s t ruc tura l and isotopic i nves t iga t ion .

Sicker Group rocks are the apparent remnant of a mid

Paleozoic volcanic arc , bui l t on oceanic crus t or perhaps on the

continental edge. After volcanism ceased the volcanic rocks were

covered by c las t i c and carbonate sediments.

Tyee Intrusions. Tyee Intrusions were or ig ina l ly mapped by Clapp

and Cooke 1917) on Saltspring Is land and northwestward to Maple Bay

on Vancouver Is land. Only recent ly a pre-Jurassic age was suspected

in view of highly al tered and par t ly schistose l i thology, en t i re ly

dis t inc t from that of Is land Intrusions. This has been confirmed by

zircon dating, which suggests a minimum age of 360 Ma They are in

par t a l tered grani toid rocks composed mainly of quartz , s e r i c i t i c

alb i te and microcl ine-per th i te , with minor epidote and chlor i te .

Commonly the texture is ca tac las t ic . rn par t they are se r ic i t e

sch i s t with elongated quartz eyes up to 1 em long, occurring as

s i l l s The schis tos i ty is para l le l to that of the intruded meta=


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volcanics and metagreywacke of the Sicker Group however the intrusive

contacts are discordant with the metamorphic grain. The apparent Early

or pre-Devonian age, i f confirmed, would indicate that part of the

Sicker Group is pre-Devonian.

Vancouver Group. The Vancouver Group is composed of an unnamed basal

unit and the Karmutsen, Quatsino and Parson Bay Formations. The

basalt unit is in par t thin-bedded black a r g i l l i t e containing Middle

Triassic Ladinian) Daonella. The beds, only known from the northeast

flank of Mt Schoen, are about 200 m thick, out are intruded by a

greater thickness of diabase s i l l s bringing to ta l thickness of

sediments and s i l l s to about 750 m

Karmutsen Formation. The Karmutsen Formation, named by Gunning

1932) is composed of tho le i i t ic volcanic rocks, up to 6,000 m thick

and underlying a large part of the island Figure 6 ). In Carlisles

1974) standard section the formation is composed of a lower member,

about 2,600 m thick, of pillow lava; a middle member, about 800 mthick, of pillow breccia and aquagene tu ff ; and an upper member,

about 2,900 m thick, of massive flows with minor interbedded pillow

lava, breccia and sedimentary layers. Except in contact zones with

granitic intrusions the volcanics exhibit low-grade metamorphism up

to prehnite-pumpellyite grade. Their age is determined by that of

the underlying Ladinian unit and by Upper Triassic , Karnian fossi ls

in sediments in the upper member. The basal t ic eruptions apparently

started with pillow lavas in a deep marine r i f t basin, continued

with aquagene tu ff and breccia as the basin became shallower, and

terminated with extrusion of subareal basal t flows. Because the

volcanics were formed on a r i f t ing oceanic crust they are probably

only in some areas underlain by Sicker Group rocks, whereas elsewhere


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COAST INTRUSIVE ROCKS

BONANZA HYPABYSSAL. ROCKS

Waterlain tuff-breccia and volcanic conglomerate,includes Harbledown clasts near base.

Intermediate and felsic si lls locally abundant.

Basalt flows, 2 to 100 feetthick. Several

discontinuous layers of pillow lava and/or pill owbreccia underlain sporadically by thin "i nterlavo"sedimentary layers occur in the upper third ofthis unit, less commonly near base.

12

1000

0Scale: feet

Predominantly r o k e n ~ p i l l o wbreccia with somewhole pillows. Lower por t well-bedded aquogenetuff and breccia.

Pill ow lavo,ordi nary close-packed bas a Itpillows.

STRATIGRAPHIC COLUMN

NORTHEASTERN

VANCOUVER ISLAND

Donald Carlisle

Block laminated siliceous and calcareousshales, pyritic siliceous meta-sedimentsbetween superabundant basaltic sills.

Predominantly coarse bioclastic limestone,partly siliceous and pyritic, with lessersiltstone. Few sills.


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they const i tu te new oceanic floor.

Quatsino and Parson Bay Formations. Upper Triassic sediments overl ie

the Karmutsen in the northern and western par t of the is land but in

the east they were mostly eroded before deposition of Upper Cretaceoussediments. The Quatsino Formation consists of limestone, mainly

massive to thick-bedded c a l c i l u t i t e varying from 25 m to 500 m in

thickness and containing ammonites and other foss i ls of Late Karnian

to Early Norian age. The succeeding Parson Bay Formation is in

diachronous contact with the Quatsino and in places l ies di rec t ly

on Karmutsen volcanics. I t is composed of interbedded calcareous

black a r g i l l i t e calcareous greywacke and sandy to shaly limestone

with the proportion and grain size of c las t i c material generally

increasing upward. The thickness is between 300m and 600 m Fossils

are the pelagic pelecypods Halobia in the Lower Karnian par t and

Monotis in the Upper Norian par t , together with many ammonite genera.

The sediments were formed in near- and off -shore basins in the quiescent

Karmutsen r i f t archipelago.

Bonanza Group. The Bonanza Group was orig ina l ly named by Gunning

1932) and at that time included Upper Triassic sediments now known

to belong to the Parson Bay Formation of the Vancouver Group.

Nomenclatural as well as geological arguments indicate that the group

should not be included in the Vancouver Group, as was done by Hoadley

1953) and previous reports by the wri ter and others 1969, 1974).

The group is mainly represented in the northwest and the southwest

of the is land and is composed of lava, tu ff and breccia, of basa l t ic

rhyo l i t i c and subordinate andesi t ic and dac i t i c composition. I t

contains i n t e rca la t ed beds and sequences of marine a r g i l l i t e and

greywacke. In the northeast par t of the i s land where only the


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sedimentary part of the group is present the rocks are referred to

the Harbledown Formation. The Bonanza represents parts of several

eruptive centres of a volcanic arc and consequently i t s stratigraphy

varies considerably. A section 2,568 m thick, measured in the

northwest at Cape Parkins, contains two sedimentary intercalat ions

225 and 75 m thick in the lower and upper part of the section. Fossils

from Bonanza and Harbledown sediments indicate mainly Early Jurassic

Sinemurian age for the northwest and northeast and Pliensbachian age

for the southwest.

Island Intrusions and Westcoast Complex. The Island Intrusions are

batholiths and stocks of granitoid rocks ranging from quartz dior i te

(potash feldspar 10 of to ta l feldspari quartz 5-20 ) to granite

(potash feldspar > 1/3 of to ta l feldspar; quartz > 20 ). They underlie

about one quarter of the i s land s surface and intrude Sicker, Vancouver

and Bonanza Group rocks. Within the Bonanza Group they form high-level

stocks and dykes of hornblende-quartz-feldspar porphyry and there is

an apparent comagmatic relationship between intrusions and volcanics.

About 40 K-Argon determinations have yielded dates of 141 to 181 a

for the intrusions and a few determinations on the volcanics are in

the same age range. Preliminary results of Sb/Sr dating of Island

Intrusions and also Bonanza volcanics have yielded a 180 a isochron

age (R.L. Armstrong, pers. comm).

The Westcoast Complex also is genetically related to theIsland Intrusions. t is a heterogeneous assemblage of hornblende

plagioclase gneiss, amphibolite, agmatite and quartz dior i te or

tonal i te , exposed in western coastal areas from Barkley Sound to

Brooks Peninsula. One age determination on zircon from the complex

has yielded near-concordant U/Pb dates of 264 a and two K-Argon

dates on hornblende from Westcoast rocks are 192 and 163 Ma. The


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18

non-marine or near-shore del ta tc ortg tn , succeeded ~ marine sandstone,

shale and thin-bedded, graded sha le - s i l t s tone sequences. Five major

cycles are distinguished of which the i r s t four have been divided

into two formations each, a lower f luvia l to del ta ic and an upper

marine formation. Coal seams in the lowest cycle of the Comox basin

and in the second cycle of the Nanaimo Basin were mined from 1850 to

about 1950. Macrofossils and microfossi ls indicate a Late Cretaceous

Santonian to Maastrichtian age. The Nanaimo Group was deposited

in a fore-arc basin between the Coast Plutonic Belt then an active

volcanic arc) and the Insular Bel t .

Carmanah and Escalante Formations. Tert ia ry c l a s t i c sediments overl ie

bevelled Island Mountain rocks in a narrow s t r i p of land along the

west coast and also are exposed on most of the continental shelf

west of the i s land. The Escalante Formation is a basal conglomerate

of Eocene age about 300m th ick , and is overlain by the Carmanah

Formation of mainly s i l t s tone and sandstone, about 1,200 m thick.

The contained microfauna of the Carmanah is mainly corre la t ive to theRefugian stage of the western United States la te Eocene to early

Oligocene) but younger beds are of Zemorrian middle to l a t e Oligocene)

age B.E.B. Cameron and W W Rau, personal communications, 1973). The

beds overl ie Insular Belt rocks as well as the Leech River Formation

of the Pacif ic Belt with clear angular unconformity. They were

deposited on the upper part of a coastal shel f area, but many beds

are sedimentary melanges that were redeposited by massive slumping.

The formations may have extended much far ther eastward but were

removed from the land-area by Late Tert ia ry and Pleistocene erosion.

Pacific Rim Complex and Leech River Formation. The Pacific Rim

Complex is exposed mainly in the western coastal area between Ucluelet


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and Tofino in Pacif ic Rim National Park. t is composed mainly of

greywacke and a r g i l l i t e with minor rib5on cher t , 5asic volcanic

rocks, limestone and conglomerate. The rocks are generally highly

faulted and sheared and in many places are tec tonic melanges. Locally

the cherts contain radiolar ians indicat ing Tithonian age A.E.

Pessagno, ~ M u l l e r1976} and the greywacke has yielded Buchias

of Valanginian age J.A. Jele tzky, pers . comm., 1972). The rocks

are therefore in par t coeval to Upper Jurassic sediments and the

Longarm Formation. Granitoid clas ts in the conglomerate indicate

probable correlat ion with the Aptian conglomerate of the Queen

Charlotte Group.

The Leech River Formation is exposed in a be l t , 2 to 12

m wide, between San Juan and Leech River Faults on southern Vancouver

Island. Like the Pacific Rim Complex the rocks are greywacke,

a rg i l l i t e and minor chert and volcanic rocks but they are largely

metamorphosed to schis t . Metamorphic grades increase from phyl l i te

inthe north to garnet-b io t i te sch is t with andalusi te porphyroblasts

near Leech River Fault in the south. There muscovite gneiss and

pegmatite with large muscovite and tourmaline crysta ls also are

present. The age of metamorphism according to severa1 K-Argon

determinations is 40 Ma

The Pacific Rim Complex and Leech River Formation are

interpreted as a tectonized assemblage of slope and trench sediments

and the i r metamorphic equivalents, formed in a Late Jurassic to

Cretaceous trench off the continental margin. They are equivalent

in age and facies to the Franciscan Terrane of California although

the metamorphic facies is apparently di ffe ren t . t is postulated

that the volcanic arc , paired to th is t rench, is the Coast Plutonic

complex and that Upper Jurassic and Cretaceous c las t i c sediments of


21/53

2

the Insular Belt were deposited in the arc-trench gap.

Metchosin Volcanics and Sooke Intrusions. Metchosin Volcanics underlie

most of the south t ip of Vancouver Island south of Leech River Fault .

They are pillow lavas aquagene tu ff and breccia and amygdaloidalflows of tho le i i t ic composition very similar to Karmutsen volcanics

in lithology and sequence but of lesser thickness estimated a t

about 4 000 m. Dyke complexes of basalt and diabase intrude and

underlie the volcanics. n the basis of Turr i t e l l a within intercalated

volcanic sandstone a t Albert Head in the middle part of the sequence

the volcanics are apparently of early Eocene age.

Chlorite schis t and hornblende-plagioclase gneiss exposed

mainly in the area west of Jordan River are interpreted as highly

deformed and metamorphosed equivalents of Metchosin Volcanics.

Hornblende from hornblende-plagioclase gneiss yielded a K Argon

date of 47 Ma.

The Sooke Intrusions are in part gabbro commonly coarse

grained and with minor anorthosite apparently underlying the Eocene

volcanics. Also present are gneissic amphibolite hornblende gabbro

angular agmatite and small stocks of tona l i te presumably formed by

migmatization mobilization and intrusion into the volcanic sequence.

Metchosin Volcanics and Sooke Intrusions could be interpreted as the

upper and lower parts of new oceanic crust formed in Early Tertiary

time.Small plutons a few km in diameter intrude various pre

Tertiary rocks of the Insular Belt in many places. They also form

s l l s in f la t lying Upper Cretaceous sediments the thickest one

a t Constitution Hil l is about 300m thick. They also intrude the

Pacific Rim Complex near Tofino. Tbey are composed of quartz diori te

and quartz diori te porphyry with hornblende and plagioclase phenocrysts


22/53

- 21 -

and of breccia t ha t may have formed in a diatreme. K-Argon determinations

have yielded dates oetween 32 and 59 Ma The in t rus ions may be sub

volcanic eruption centres, aligned on three subcrustal f racture zones,

radiat ing from the Tofino area respect ively towards Zeba11os, Mt

Washington and the upper Nanaimo River. However, no fractures or

faul ts clearly re la ted to the intrusions have been iden t i f i ed Carson,

1973).

Sooke Bay Formation. The Sooke Bay Formation modified from Sooke

Formation to allow dist inct ion from Sooke Intrusions ) occurs in

depressions on the erosion surface of Metchosin Volcanics and SookeIntrusions. t is probably less than 200 m thick and does not extend

north of Leech River Fault. t contains local ly coquinas of shallow

water pelecypods indicat ing Miocene age, but the microflora may

indicate early Pliocene age as well Shouldice, 1971). The formation

is of fluvial to del ta ic or igin .

Late Tert iary volcanic rocks are exposed in small areas

south of Port McNeill. They are basa l t , almost unconsolidated tu ff

and breccia, volcanic boulder conglomerate and l igh t coloured dacite

tuff . Whole-rock K-Argon determinations yielded dates of 7.6 and

7.9 Ma

Structure. The st ructure of the is land is almost en t i re ly dominated

y steep fau l ts . Only the f lysch-type Pennsylvanian and Jura

Cretaceous sediments and associated thin-bedded tu ffs show i socl inal

shear-folding. Faulting and r i f t i n g probably occurred during the

outflow of Karmutsen lavas in Late Triassic time, establ ishing the

northerly and westerly directed fau l t systems affect ing Sicker and

Vancouver Group rocks. Faulting in a northwest di rec t ion , accompanied

y southwestward t i l t i n g in the west, and l a t e r by northeastward


23/53

- 22 -

t i l t i n g in the east ( the l t t e r affect ing Upper Cretaceous sediments)

occurred in la te Mesozoic to Early Ter t iary time. Faulting in a

nor theaster ly direct ion affected younger Mesozoic and early Tert iary

rocks. The important San Juan and Leech River Faults were act ive

respect ively in la te Mesozoic and Early Ter t iary time and may be

st ructures associated with subduction zones.

Mineral Deposits. Much of the coal in the Nanaimo Group, worked

since 1850, has been depleted, especia l ly in the Nanaimo Basin. In

the Comox Basin there are s t i l l some doubtfully economic reserves

of high vola t i le bituminous coal . The most important metall ic ore

deposi ts are: (1} massive sulphides of Zn, Cu Pb, Au Ag in Sicker

volcanics Western Mines}; (2 ) skarn deposits of Cu and Fe in Quatsino

1 imestone (Argonaut, Texada, Coast Copper, etc . ;} (3) porphyry copper

deposi ts surrounding and within high level Is land Intrusions (Island

Copper) or in the Sooke Intrusions Mt. a s h i n g t o n ~Catface); 4 ) Cu

in shearzones in amphibolized Sooke gabbro (Jordan River).

Glaciation. The ent i re is land was glacia ted during the Pleistocene.

During an older glac ia t ion , perhaps ear ly Wisconsin, the ent i re is land

was covered by an ice-sheet , continuous across the Georgia Depression

and generally flowing southwestward Peaks with ice margins at

present 1,000 to 1,500 m levels formed monadnocks and are readi ly

recognized in the landscape. In one or more l a t e r glacia l events

ice probably accumulated in a northern, a middle and a southern centre,

formed piedmont glaciers in Nimpkish, Alberni and Cowichan Valleys

and flowed out from these with ice tongues into many valleys now

occupied by finger lakes. The S t ra i t of Georgia was also occupied

y ice that flowed south across the Gulf Islands and the Victoria

Sooke region. Marine transgression during deglaciation at ta ined


24/53

23

elevations of 150 m along t ~ eas t coast and 5 m along the west

coast The complex history of glacia t ion of the i s land is s t l l

awaiting detai led analysis


25/53

FIGUR

0

MILES

20 40

v v v vv v v ..;vi

EiJ

TI l

.:

: + _ I

: \ ~ \ \ l' 0 , " { ~ J

V N C O U V E R I S I . A N O

Not revised since 1972

l E G E N D

TERTIARY SEDiMENTS

TERTIARY INTRUSIONS

TeRTIARY VOLCANICS

LATE MESOZOICSEDIMENTS

MIDDLE TERTJARY

E RLY TO MIDDLETERTIARY

EARLY TeRTIARY

LATE JURASSIC TOCRETACEOUS

LEECH RIVER FORM TION JURA- CRETACEOUS?

ISLAND INTRUSIONS JURASSIC

BONANZA GROUP EARLY JURASSIC

QUATSINO. PARSON BAYLATE TRIASSIC

FORMATIONS

KARMUTSENTRIASSIC

FORMATION

SICKER GROUP LATE PALEOZOIC

METAMORPHICJURASSIC OR OLDER

COMPLEXES

24


26/53

5

Part I I

Roadlog for 4-day Geological excursion in south and central

Vancouver Island

The four days of th is f ie ld t r i p deal each with dis t inc t

parts of the geological column of the i s land.

ay 1 is spent in the Sooke-Metchosin area examing rocks

in the Metchosin Block south of Leech River Fault . They are the

pillowed and the layered lava flows aquagene tuffs and breccias of

the Eocene t h o l e i i t i c Metchosin Volcanics. The underlying rocks

comprise a dyke complex and gabbro and derivat ive quartz d i o r i t i cto t rondhjemit ic intrusive rocks.

ay 2 begins in the ci ty of Victoria from where the tour

proceeds along the Island Highway and some detours via uncan and

Nanaimo to Parksvi l le . Par t ic ipants will see the Colquitz and Wark

Gneiss basement complex, the Jura-Cretaceous Leech River Formation

and tha Paleozoic Sicker Group and Tyee In t rusions.

ay 3 is spent mainly alongside Sut t le Lake, following a

drive from Parksvil le via Courtenay and Campbell River. Rocks to be

seen include addit ional volcanics and the Butt le Lake limestone of

the Sicker Group, the pillowed c las t ic and layered members of the

Upper Triass ic Karmutsen Formation overlying Upper Triassic sediments

intruded by subvolcanic Jurass ic rocks and gran i to id Is land Intrusions.

ay 4 is spent driving across the is land via Beaufort Range,

Alberni Valley Sproat Lake and Kennedy River across the Island

Mountains to Pacific Rim Park on the Pacific Ocean. Additional

outcrops of the Karmutsen and Island Intrusions plus some of the

Triassic Quatsino limestone and Jurassic Bonanza volcanics are seen

but the main objective is the sediments and volcanics of the Jura-


27/53

6

Cretaceous Pacif ic Rim o m p l e ~with t charac ter is t ic melanges. The

return t r ip leads via Alberni Parksville to Nanafmo and from there

y B.C. Ferries to Vancouver.


28/53

CONTACT . . . . . . . . . .CROSS-FAULT . . . . . . . . . .REVERSE FAULT

(teeth on upthrown s idel uuoo __ _

SYNCLINE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . - * -M I l S

5 0KM

5 1

7

FIGURE

VICTORIA MAP-AREA(92 B

SOOKE GABBRO [ 9JMETCHOSIN VOLe'S [ i l lLEECH RIVER

SEDIMENTS

ISlAND INTR STYEE INTR S

COLQUITZ GNEISSW RK DIORITE

N S ~V ~

K V ~

s s ~s v ~

Stuart

~ ~ N S~ ~ Ia

~ f .

QUATERNARY

SOOKE SED S : C E N O Z O I C

NANAIMO 1 LATERSEDIMENTS I MESOZOIC

BONANZA VOLC S I EARLIERKARMUTSEN VOLC SI MESOZOIC

SICKER SED SSICKER VOLC S

l PALEOZOIC


29/53

8

D Y 1

METCHOSIN VOLCANICS ND SOOKE INTRUSIONS EARLY TERTIARY)

From Victoria via Langford to Happy Valley Road

Mileage

11.9 STOP 1-1. Amygdaloidal basal t flows of Metchosin Volcanics

a t Englewood Road. Like many outcrops in the region the

bluff is well glaciated. The subaereal basal t flows are

almost horizontal and 2 to 4 m thick. They contain amygdu)es

f i l l ed with quartz and local ly chlori te and tops and bottoms

are dist inct in a few places. The rock is composed of a

very fine ~ .05 mm} holocrystalline assemblage of plagioclase

an< 50), colorless pyroxene and ol iv ine , altered to reddish

brown iddingsite and magnetite. Metchosin Volcanics are

mainly of tho le i i t ic composition: Si0 2 = 46.5 - 50.4 ;K2o = 0.06 - 0.49 ; Na 2o = 1.9 - 4.2 . (8 analyses ofrandom s a m p l e s ) ~On an FM diagram they plot in the

tho le i i t ic f i led and on the Alkali-Si0 2 diagram they are

subalkaline. The flows are the apparent subaereal part

of a sequence that begins with submarine pillow lavas.

Continue for 1.6 mile on Happy Valley Road.

13.5 STOP 1-2. Pillow lavas of Metchosin Volcanics. The outcrop

shows pillow lavas of the lower submarine part of the formation.

The pillows are up to about 30 em high and more than 1 m wide;

there also are some lava tongues. Amygdules appear to be

concentrated in the top parts of the pillows.

Continue on Happy Valley Road, turn l e f t towards Colwood

and r ight on Duke Road.


30/53

- 29 -

18.3 STOP 1-3. Tuffs with foss i l bed and pillow lavas. The t idal

exposure behind the residence a t 3817 Duke Road exhib i t s well

bedded aquagene tu ff and minor basa l t . One sedimentary lens,

about l m thick, contains a great number of slender conical

gastropods, ident i f ied by W O Addicott of the U.S. Geological

Survey as Turr i t e l l a cf T. uvasana hendoni Turner, indicat ing

a probable early Eocene age. Please note: This outcrop is on

private property. The owners have over the years been very

cooperative in l e t t ing many groups of geologis ts view the

outcrop, but do not wish foss i l s to be collected A limestone

lens far ther west has yielded orbi to id foraminifera, probablyDiscocyclina according to B.E.B. Cameron. The sedimentary

layers are believed to be in the middle par t of the Metchosin

Volcanics. Pillow lavas are well exposed on the i s l e t s

far ther west.

Continue north on Duke Road turn r ight on Albert Head

Road enter gate and proceed to uracetrack oval" on south

side of Albert Head Military Reserve; turn r ight .7 mile

af te r gate.

19.8 STOP 1-4. Aquagene tu ff and breccia with s l l s and dykes.

In the cove jus t eas t of the oval , breccia with lava fragments

up to 30 m in size is interbedded with aquagene tu ff . The

breccia is not a typical pillow breccia (they also occur in

Metchosin but cannot be shown conveniently) but rather a

lahar- l ike deposit with subangular fragments of fresh, local ly

scoriaceous basal t in a mudstone matrix. The tu ffs are well

bedded and show subangular fragments tha t in thin section

appear to be mainly shards and globules of redbrown palagonite,

minor feldspar, a few minute shel l fragments, bonded by


31/53

- 30 -

secondary quartz, chlor i te and prefmfte. Farther west along

the shore the beds contain layers with shell debris. The

beds are cut by dykes and s l l s of blocky to columnar basal t .

The l a t t e r, although they resemble a flow are different in

appearance from typical ly massive, non-columnar Metchosin

flows.

Return to Happy Valley Road and turn l e f t to Metchosin

and Rocky Point.

27.1 STOP 1-5. Faultzone near crossing of abandoned C N Railway

and Rocky Point Road A wide faul t zone from Pedder Bay to

Sooke Basin separates northeast dipping Metchosin tuffs from

the basal gabbro and dyke complexes of Rocky Point and East

Sooke Peninsula. The rocks have been converted to flaky

serpentine. The general movement is di ff i cu l t to see but

could be oblique s t r ike-s l ip , dipping about 20 SE

Proceed south towards Becher Bay; outcrops where road

makes loop near coast.

31.5 STOP 1-7. Dykes and epidotized sediments. The cut shows

well layered nearly f l a t lying e.pidottzed si l ts tones.

In thin section they are a f ine-grained 0.02 mm aggregate

of quartz, minor plagioclase, epidote, and prehnite in veinlets.

They are cut by numerous dykes tha t have been recrys ta l l ized

into a plagioclase-ac t inol i te mesh with scat tered magnetite.

Plagioclase is in very thin la ths , 0.3 mm long, and

act inol i te is in bundles and in veinle ts . The dykes were

feeders for Metchosin Volcanics but were la ter thermally

me tamo rp hosed.

Proceed and turn l e f t to East Sooke Park.


32/53

- 31 -

31.5 STOP 1-7. Sooke Gabbro, East Sooke Park, Aldridge (Pet roglyph)

Point . There i s about a mile hike via a good fo o t - t r a i l to

Aldridge Point , with several markers to Petrog1yphs The

gabbro i s coarse grained and has a fa in t ver t ica l layer ing ,

s t r ik ing northeas ter ly. A th in sect ion shows an almost

unal tered equigranu lar, anhedral assemblage of variously

twinned c lear bytownite (An 8 0 ~ , colour less pyroxene with

exsolut ion lamellat ion and including some plag ioc lase and

almost unal tered ol iv ine . Dykelets of l igh te r coloured

rock are of s imi lar composition but r icher in fe ldspar and

ol iv ine and with minor i n t e r s t i t i l pyroxene. The steepfo l ia t ion or layer ing in the gabbro suggests mult iple in t rus ion

of ver t i ca l ly planar bodies . The well preserved petroglyphs

represent a sea l ion and a salmon and are examples of an

Indian a r t form t ha t is wide spread along the Pacif ic Coast.

According to the Indian legend long years ago a grea t

supernatural animal l i ke a sea- l ion ki l l ed many of the

Becher Bay Indians when canoeing. The t r ibe became nearly

ex t inc t ; the remaining members were a f ra id to go on the

water unti l one day a mythical man caught the sea- l ion and

turned him in to the stone representa t ion as seen on Aldridge

Point .

After leaving the park turn l e f t onto East Sooke Road.

38.6 STOP 1-8 . Olivine leucogabbro ( anorthosi te ) . A small

roadcut , about ~ m i l past East Sooke, shows very coarse

grained leucogabbro. Although the hand-specimen appears

to cons is t mainly of plagioclase , a modal ana lys is showed

77.6 bytownite (An 75+), 17.0 pyroxene and 5.4 ol iv ine .

The rock, with less than 90 plag ioc lase . does not qual i fy


33/53

- 34 -

d io r i t e . Th e original Paleozoic ?}_ gabbro has been

recrys ta l l ized to hornblende-plagioclase gneiss and subsequently

has suffered retrograde metamorphism to low greenschist grade.

Plagioclase is a lb i t ized and se r ic i t i zed and hornblende is

par t ly changed to epidote, zo is i te and ch lo r i t e . The gneiss

may have been oceanic crus t below the Paleozoic Sicker Group

volcanic te r rane . However superposit ion of the volcanics

on Wark Gneiss has not been establ ished anywhere.

Via Cedar Hill Crossroad, Mackenzie and Tillicum to

Trans Canada Highway; westward on highway to jus t past Shell

station a t Goldstream.

21.8 STOP 2-3. Leech River Formation. The formation consists

mainly of i soc l ina l ly folded f lysch-type sediments, converted

to phy l l i t i c sch is t s . The outcrop is about km north of the

leech River Fault, the important st ructure tha t separates the

formation from Metchosin Volcanics. The s la ty cleavage of

the schis t is parallel to the faul t at azimuth 300. The

cleavage shows kinkbands and also sl ickensides dipping 50

southeast , perhaps indicat ive of oblique movement on the

fau l t . The formation, formerly believed to be Paleozoic,

is now with some assurance corre la ted with the Upper

Jurassic to Cretaceous Pacif ic Rim Complex although no

foss i ls are known in the Leech River. Both major unitsare believed to be la te Mesozoic slope and trench deposi ts ,

formed along the edge of the continent . Several K Argon

dates on metamorphic b io t i t e from schis t and gneiss in the

formation vary from 36 to 42 Ma indicat ing la te Eocene to

ea r l i e s t Oligocene metamorphism. and probably the time of

l a t e s t deformation.


34/53

- 35 -

Proceed on highway to knoll on r i ~ t side with hydro

towers, a t highway-crossing of power-line.

25.4 STOP 2-4. Leech River Formation, ribbon cher t . The base

of the hydro-tower is composed of east-west s t r ik ing ver t icalribbon cherts. The beds of black to greenish grey, whitish

weathering chert are 1-4 m thick and separated by films of

graphit ic matter. Dragfolds in the beds are believed to be

soft-sediment slump-folds. Thin sect ions show them to be

s i l i c i c rocks, composed of a fine dust of quartz , feldspar

and ac t ino l i t e . Sparse, poorly preserved radiolar ians have

been found. The rocks are simi lar to those of Pacif ic Rim

Complex, where in one place less recrys ta l l ized dark-red

chert has yielded a good radiolar ian fauna of Upper Jurassic

age see Stop 4-6). The chert is probably corre la t ive to

chert on San Juan Island, about 3 km west of here. The

San Juan cherts have unti l now been dated as Permian on the

basis of associated fusul inid-bearing limestone Danner,

1966), but D.L. Jones and J . Whetten pers. comm. have

found Tithonian radiolar ians in them as well . The outcrop

also contains s i l l s of fresh, ca tac la s t i c gabbro.

Proceed on highway 1.3 miles to l e f t bend.

26.7 STOP 2-5. Leech River Formation, greywacke and a r g i l l i t e

Outcrops on both sides of highway show th ick greywacke units

up to 6 em thick, in places with r ip-up shale fragments,

separated by th in a r g i l l i t e laminae, th in graded units a

few m thick, and thick a r g i l l i t e uni ts . A thin section

shows angular grains of mainly quartz and quar tz i te , less

plagioclase, and minor ch1ori t ized mafics and volcanic fragments


35/53

6

in a matrix of fine quartz, epidote, and ch lo r i t e . The cut

shows close folds in the greywacke and local ly good axial

cleavage.

Proceed on highway 1.0 mile to next curve, j u s t south

of the Dutch Latch

27.7 STOP 2-6. I f t r a f f i c permits) . Faultzone. The fau l t i s

an important northeast trending c ross - fau l t , exposed on the

eas t side of the highway. t off se t s the Leech River Fault

and the Leech River Formation that i s here in contact with

the Wark-Colquitz Gneiss to the northwest.

Proceed to second Malahat Viewpoint.

31.9 STOP 2-7. Tyee Intrusions ?. The a l t e r ed gran i t i c rock on

the detour par t ly covered by grouting} i s a grani te with

about 35 andesine an 35+}, 35 microperthi te , j u s t over

20 quartz and a few percent ch lo r i t e a f t e r b i o t i t e , and

prehnite. t i s s imi lar to some par ts of Paleozoic Tyee

Intrusions, but the age is s t i l l to be determined with

zircons. Below the viewpoint the sheared l imestone in the

Bamberton quarry, in th rus t contact with the gran i te , may

be Triass ic or Paleozoic. On a c lea r day the lookout affords

a spendid view of Saanich Peninsula, the Canadian Gulf Islands,

the American San Juan Islands and the Quaternary volcanic cone

of Mount Baker.

Proceed via highway to Duncan and turn r ight towards

aple Bay. Continue north towards Arbutus Point. On t he

way there are outcrops of Nanaimo Group s i l t s tone Haslam

Formation, Santonian) that with the basal Comox conglomerate

and sandstone unconformably overl ies Sicker Group volcanics.


36/53


37/53

112 0 0

11 7. 1

- 38 -

angular quartz , plagtoclase and b.Joti:,te. l n carlionate matrix

and must have been derived from granitoid rocks.

At Nanoose turn r ight to Dolphin Beach.

STOP 2 ~ 9 Sicker Group sediments. Seashore behind homes onBlueback Drive. The sediments exposed here are unevenly

bedded a r g i l l i t e and calc-areni te that exhibi t pronounced

slump-folding. The beds over l ie plagiophyric basal t or

andesite tha t contains patchy (high-low temperature?)

plagioclase phenocrysts an 55+) in a matrix of andesine

microl i tes , b io t i t e and magnetite. Fragments and a few

angular blocks of the volcanic rock are present within the

calcareni te beds. The clas t ic beds thus were apparently

la id down on a submarine slope of a volcanic landmass that

was bordered by carbonate reefs . Biot i te in the volcanic

rock and rec rys ta l l iza t ion of the limestone indicate thermal

metamorphism by the body of granodiori te that intrudes the

sediments less than ~ km eas t of the outcrop. n Ballenas

Islands, about 6 km north of th is point , the same a r g i l l i t e -

limestone formation has yielded brachiopods as well as

fusul in ids . The l a t t e r are according to C.A. Ross Wedekindella

sp. and Eoschubertel la sp . , indicat ing a Middle Pennsylvanian

age.

STOP 2-10. Nanaimo Group sediments, with angular unconformity

on Sicker Group. I f t ime and t i d e s p e r m i t , return from

Dolphin Beach and take road to Clayton s Marina and Cottam

Po i n t ,

The t i d a l exposure s show s h e a r f o l d e d t u r b i d i t i c

greywacke and a r g i l l i t e o f the Si c k e r Group, overlain


38/53


39/53

SOUTH FIGURE 9

~ O Y J

0~

. \c,- ~ (

q _ ~

~ 0 ~

r UPPER CRETACEOUS. NA NAIMOi l l GROUP Clastic sediments.

MIDDLE JURASSIC .ISLANDINTRUSIONS. Granitic rocks.

LOWER JURASSIC BONANZASUBGROUP Andesite, Rhyodacite,minor sediments.

q_l..t:j

~ l . .

~ 0 ~

0 >

Scole - Mile0 5

Scale- Km

UPPER TRIASSIC. QUATSINO,PARSON BAY FORMATION.Carbonate ,clasti c sediments.

UPPER TRIASSIC AND OLDERKARMUTSEN FORMATION.

A) Basaltic lava.

8) Pillow basalt, breccia.

~ I ,

.SJ \ ~$)'li

C J ~ f ~

- 0 ~ q

, , o ~

~

geology of vancouver island

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