geology of ontario - brock university · pdf filegeology of ontario 8/5/2005 1 the geology of...

Geology of Ontario 8/5/2005

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The Geology of Ontario

Gregory C. FinnDepartment of Earth Sciences

Brock University

Outline• Discuss the geologic make-up of Ontario• Examine four geologically significant

features in Ontario– The Sudbury Structure– The Thousand Islands– Niagara Falls– Oakridges Moraine


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Ontario’s Geologic Legacy• Geologic history dates back to 3.25 billion

years• Rocks present represent

• ocean floor• deep crustal sections• remnants of ancient mountain chains• deep sea sediments• ancient and modern glacial deposits

• Rocks divided into 4 geologic provinces

Geologic Time ScaleEon Era

Phane

rozoic Mesozoic

Cenozoic

Paleozoic

Late

Middle

Early

Prot

eroz

oic

Late

Middle

Early

Arch

ean

Had

ean

Prec

ambr

ian

570

1,000

1,750

2,510

3,000

3,400

4,000

4,650

Age Era PeriodQuaternary

Tertiary

Ceno

zoic

Meso

zoic

Cretaceous

Jurassic

Triassic

Permian

Pennsylvanian

Mississippian

Devonian

Silurian

Cambrian

Paleo

zoic

Ordovician

Precambrian

Ca

rbo

nife

rou

s

570

505

438

408

360

320

286

245

208

144

65

Age Era Period Epoch

Holocene

Pleistocene

Pliocene

Miocene

Oligocene

Eocene

Paleocene

Qua

tern

ary

Te

rtia

ry

Ce

no

zo

ic

Cretaceous

66.4

57.8

36.6

23.7

5.3

1.6

0.01

Age

Ages in Millionsof Years3.25 billion years Oldest rock in Ontario

Geologic Provinces• Formed at different times - three (Superior,

Southern and Grenville) collectively form Ontario’s portion of the Canadian Shield, and form the bedrock in northern and central Ontario

• The fourth, consists of Paleozoic, Mesozoic and Cenozoic rocks, and occur as sediments which covers the ‘bedrock” in eastern, southwestern and extreme north of Ontario


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Geologic Provinces of

Ontario

(From ROCK ONtario1994)

Geologic Provinces (continued)

• Lithologies (rock types) present• e.g. volcanic

» basalt vs. andesite vs. rhyolite

• Age• based of geochronologic studies to determine the ages of the

lithologies present

• Structure and Metamorphism• intensity of deformation and degree of metamorphism

preserved/recorded

• Metallogeny• Types of mineral deposits present

Criteria for defining Geologic Provinces


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Superior Province• Oldest part and covers most of Northern Ontario• Can be further subdivided, based on rock type into

12 smaller subprovinces:• Granite-Greenstone - plutonic and volcanic

» Uchi, Wawa, Abitibi

• Sedimentary - range of sedimentary rock types» English River, Quetico

• Plutonic - mainly granite» Winnipeg River

• High Grade - deep crustal slice of a greenstone» Kapuskasing Zone

Superior ProvinceSubprovince Types

Bird River

MinnesotaRiver Valley

Winisk

Thompson Belt

N

0 250 Km

Hudson Bay

James Bay

Manito

baOntar

io

CanadaU.S.A.

Southern Province

GrenvilleProvince

Ontario

Quebec

Labrador Trough

Sugluk

CapeSmithBelt

Trans - Hudson Orogen

St. Catharines

Pikwitonei

Sachigo

Berens River

UchiEnglish River

Winnipeg RiverWabigoon

Wawa

Wawa

Quetico

Quetico

Kapu

skas

ing

Pontiac

AbitibiOpatica

Nemiscau R.

AshuanipiBienville

La Grande R.

Opinica R.

Minto

High Grade

Plutonic

Volcanic

Metasedimentary

Modified from Percival 1989


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Superior Province Highlights• Subprovinces separated from each other by

faults• Granite-Greenstone

• long narrow belts of volcanic rocks which were once island arcs - much like modern day Japan

• rocks formed on ancient sea floors, in ancient volcanoes

• host to world famous mines – e.g.

» gold at Hemlo,» copper, zinc, and silver at Kidd Creek

A portion of the Superior Province in NW Ontario. Greenstone belts (in green) are remnants of ancient volcanic rocks.

0 5 km

RichardsonArm

Rapson

StullRapson

Bay

StullLake


Sample Test Questions1. List three minerals that you would expect to find in each of the following rocks:

– Diorite Syenite Phyllite Marble

2. Define each of the following terms:– metamorphic rock texture euhedral Porphyroblast

3. Minerals are classified as belonging to either the silicate or non-silicate groups or classes. Provide the characteristics that define two non-silicate classes of minerals and give examples for each class:

– a) b)

4. Describe the three types of material produced as a result of volcanic eruptions:– a) b) c)

5. One identifiable group of metamorphic rocks are the foliated. What 2 processes result in the development of the foliation?

• a) b)

Ten questions, equal value, 60 minutes


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RECAP• Finished off Metamorphic rocks

– Index minerals, isograds– Prograde vs retrograde

• Metamorphic Environments– Thermal or contact– Dynamic– Dynamothermal

• Geology of Ontario– Geologic provinces

• Lithology, age, structure/metamorphism, metallogeny– Superior Province

The Southern Province


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North Channel

Cobalt Embayment

Sault Ste. Marie -Elliot Lake Area

Sudbury -Espanola Area

SUPERIOR PROVINCE

GRENVILLEPROVINCE

SudburyStructure

Southern Province• Rocks present range in age from 2.49 to 2.21 billion years • Consists mainly of sediments (3,000 to 15,000 m thick)

• conglomerate, sandstone, siltstone, mudstone

• Deposited by rivers, wind, glaciers etc. in an ancient ocean• comparable to the modern Atlantic Coast of North America

• Following deposition a period of mountain building occurred when Ontario collided with another continent

• preserved along the north shore of Lake Huron

• 1.11 billion years ago the the Earth’s crust of the Southern Province cracked forming a rift valley along which igneous rocks were formed

• volcanic rocks around Lake Superior• plutonic rocks around Lake Nipigon


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9


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1.85 Billion Years Ago in the Southern Province

• Sudbury Event

Geologic Cross Section - Sudbury Area ~ 1.85 GaImpactor/Bolide~10 km diameter~ 25 km/sec

HuronianSedimentaryRocksN S

230 km

70 km

Mantle

Lower Crust

Archean Basement Rocks

Nipissing Magma Chamber

NipissingDiabase

CreightonGranite

Melt + Vapour

70 km

Archean

Huronian

Lower Crust

EjectaCurtain

Cratering FlowField

Time ~ 5 seconds


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70 km

Melt + Vapour

Archean

Huronian

Lower Crust Transient Cavity atMaximum Depth

Time: ~1 minute

Formation of Proto-Footwall Breccia and Sublayer,

Ejecta

70 km

Time: ~2 minutes

Transient Cavity at maximum diameterUplift of cavity floor and beginning of rim collapse

70 km

Time: minutes

Near completion of upliftand rim collapse

Formation of additional Sudbury Breccia, Footwall Breccia and Sublayer


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70 km

Time: minutes

Final Form Formation of SIC, BasalOnaping and Gray Member

Fall-back, CoolingLocal Readjustments

Formation of Black Onaping,Cooling and differentiation of SICIntrusion of Offset Dikes, Ores

SIC

70 km

Time: ~ Hours to 105 a

70 km

Time: 1.85 GaPresent Day

Penokean and Grenvillian


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The Sudbury Structure• The preserved remnant of this meteorite impact is

termed the Sudbury Structure composed of:• the Sudbury Basin• the Sudbury Igneous Complex

– World famous for:• its origin by

meteorite impact• Nickel deposits


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Subdury Mining History• Sudbury copper-nickel ores have been mined since 1883

• Early smelting took place out in the open - Copper Cliff

• Until WWII only copper was produced

• During WWII it was discovered that the addition of nickel served to strengthen steel - “armour plate”

• Ontario produces 2/3 of Canada’s nickel (2nd to Russia in terms of worldwide production)

• In 1993 17 operating mines produced 124 million kilograms of nickel worth of $835 million

• A total of 45 ore minerals are present at Sudbury, yielding in addition to Ni and Cu, Au, Ag, Co, Pt, Pd, Se

The Grenville Province


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LakeHuron

GeorgianBay

Sudbury

Pembroke

Kingston

Quebec

100 km

Central Metasedimentary Belt

Central Gneiss Belt

Tomiko

Algonquin

Nipissing

ParrySound

Boundary Zone

Frontenac

Shar

bot L

ake

Maz

imaw

Elzevir

BancroftBoundary Zone


Bancroft

The Grenville Province

Grenville Province• Consists of a patchwork of many different pieces of crust

or terranes, which collided to form a major mountain range.

• Rocks present range in age from 1.76 to 1.00 billion years • Rocks have been baked, squeezed, stretched and twisted

into metamorphic rocks by a series of mountain building events 1.18 to 1.00 billion years ago.

• Consists of two major belts:• Central Gneiss Belt• Central Metasedimentary Belt

• Complex history still being unraveled by geologists

Central Gneiss Belt• Oldest part of Grenville Province• Nipissing Terrane oldest

• metamorphosed sedimentary and igneous rocks

• Parry Sound Domain Youngest• volcanic island arc, formed at some locality far removed from Ontario

(Suspect Terrane)

• Consists of metamorphic rocks that have been subjected to intense heat (~800°C) and pressure (up to 10 kbars) due to burial during mountain building activity

• Central Gneiss Belt exposes deep sections of Earth’s crust the was buried to depths of 20 to 30 km

• Responsible for scenery in Algonquin Park


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Central Metasedimentary Belt• Largest section of Grenville Province• Consists of two sections

• A ‘Superterrane’ (Bancroft, Elzevir, Mazinaw, Sharbot Lake terranes)

– mixture of sedimentary and volcanic rocks formed ~1.30 billion years ago

– metamoprhosed 1.25 billion years ago when the four terranescollided and at the same time intrusions of granite ‘stitched’ together the terranes

• The Frontenac Terrane– lots of marble, quartzite and gneiss, but no volcanic rocks,

formed 1.28 billion years ago

• Story of erupting volcanoes, island arcs, erosion of sediments and mountain building ( = Himalayas)

• Volcanoes formed in a tropical environment, comparable to present-day Indonesia‘


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The Thousand Islands


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Kingston

Gananoque

Westport

Athens


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Phanerozoic Lithologies

Paleozoic (early life) and Mesozoic (middle life) Eras

Paleozoic Lithologies

• Occur in Southeastern Ontario, Southwestern Ontario and the Hudsons Bay and James Bay Lowlands

• Essentially flat lying sedimentary rocks• In general they get younger as you move

from east to west in Southern Ontario


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The Niagara Escarpment

• Is NOT a fault scarp• It is an erosional

feature• Extends from:

• up state New York through Ontario, along the Bruce Peninsula, into Michigan

• Represents a series of sediments deposited in an inland sea


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Niagara Falls

0 1 2 km

N

Niagara Falls(Ontario)

Niagara Falls(New York)

St. Davids Buried Gorge

Niagara Escarpment

Whirlpool State Park

WhirlpoolRapidsGorge

Whirlpool

Eddy Basin

Lyell/JohnsonRidge

NiagaraGlen

Queenston

Lewiston

PowerStations

PowerStations

AmericanFalls

Canadian orHoreshoe Falls

Niagar

a G

reat

Gor

ge

Niagara River


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From Tinkler 1993

0 1 2 km

N


Niagara River

?

?

?

12500 BP

Lake Iroquois 0 1 2 km

N

Niagara RiverSt. Davids Buried Gorge

11500 BP

Recently Emerged

Now Dry

Submerged

Dry LandNewly Excavated Gorge

Exhumed Buried Gorge

Stages in the Recession of Niagara Falls

From Tinkler 1993

0 1 2 km

N

Niagara River


NiagaraGlen

10500 BP

0 1 2 km

N

Niagara River


NiagaraGlen

5500 BP

Recently Emerged

Now Dry

Submerged




From Tinkler 1993


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0 1 2 km

N


Sediment

Niagara River

Buried GorgeExhumed

4500+/-150 BP

LakeTonawanda

high

0 1 2 km

N

Niagara River


Lyell-Johnson Ridge

4000-3500 BP

Recently Emerged

Now Dry

Submerged




From Tinkler 1993

0 1 2 km

N

Niagara River


LakeTonawanda

drained

Now

Recently Emerged

Now Dry

Submerged




From Tinkler 1993

Distance Up River From Lewiston In Kilometres

14C

Age

for L

ocal

ities

2000

4000

6000

8000

10000

12000

1400016000

00 1 2 3 4 5 6 7 8 9 10 11 12

NiagaraGlen

Lewiston

PresetFalls

ExhumedGorge

Sediment slug to Lake Ontario

Whirlpool State parkAbove Gorge Walls

Recession Rate of Niagara Falls

From Tinkler 1993


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Historic Crest Position

Niagara Falls • Mean flow is ~ 5,760 m3s-1

• Since 1953 half of this is extracted for power generation

• At night in the summer and throughout the winter 3/4 of this is extracted from the river

• Effect is that the recession rate of 5 ft yr-1 from 19th Century is greatly reduced

The Oak Ridges Morraine


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Geomorphology of Toronto Region

From: Toronto Rocks, 1998

Digital Elevation Model wof Oak Ridges Moraine. Of particular note in this scene is the extremely linear character of the Oak Ridges Moraine across the

centre of the image. Major difference in terrain features north and south of the moraine can be recognized. North of the moraine the terrain is dissected by large valleys and has extensive drumlin uplands. South of the moraine the

elevation is lower, the topography smoother and there are fewer valleys and drumlins.

http://sts.gsc.nrcan.gc.ca/orm/landscapes.asp

Final Stages of Last Ice Age:Formation of Oak Ridges Moraine



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Well stratified matrix-supported gravels (1) have been eroded and the resulting channel filled with a massive sand-silt diamicton (2). These deposits are part of the Paris Moraine, a thick accumulation of glacial fluvial deposits and illustrate the high energy associated with ice-front sedimentation.

http://sts.gsc.nrcan.gc.ca/orm/sediments.asp

These medium sands have well-developed planar laminations (1) resulting from deposition under high velocity flows commonly associated with glacial fluvial conditions. These planar laminated sands have been truncated by an erosional surface (2) which is overlain by a second phase of deposition (3). These types of deposits are common within the Oak Ridges Moraine, a regional glaciofluvial - glaciolacustrine complex http://sts.gsc.nrcan.gc.ca/orm/sediments.asp

Cross Section Oak Ridges Moraine:13,000 years ago



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Geologic Cross Section:Oak Ridges Moraine to Lake Ontario


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