geology of vancouver island
TRANSCRIPT
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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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V N C O U V E R I S L N O
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TERTIARY SEDIMENTS
TERTIARY INTRUSIONS
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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
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DALERT BAY-CAPE SCOTT,92 L -1021
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20 40
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
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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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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
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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
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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
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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
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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
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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
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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-
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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.
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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
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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.
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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
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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.
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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
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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.
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- 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
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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.
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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
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SOUTH FIGURE 9
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r UPPER CRETACEOUS. NA NAIMOi l l GROUP Clastic sediments.
MIDDLE JURASSIC .ISLANDINTRUSIONS. Granitic rocks.
LOWER JURASSIC BONANZASUBGROUP Andesite, Rhyodacite,minor sediments.
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UPPER TRIASSIC. QUATSINO,PARSON BAY FORMATION.Carbonate ,clasti c sediments.
UPPER TRIASSIC AND OLDERKARMUTSEN FORMATION.
A) Basaltic lava.
8) Pillow basalt, breccia.
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