southern canadian cordillera · 2007-12-04 · 65º 60º rubyruby 160º 160º 155º 155º 150º...

65º

60º

RubyRuby

160º

160º

155º

155º 150º 145º

Yukon-TananaYukon-Tanana

BrooksBrooks

W

PrinceWilliamPrinceWilliam

Kaltag Fault

TintinaFaultTintinaFault

Denali Fault

Con

tact

F

Bord

er R

ange

s FAle

utia

n Tre

nch

TransitionFault

PACIFICPLATE

YakutatYakutat

KoyukukKoyukukRubyRuby

TT

T

T

SMSM

A

ChugachChugach

70º

AnchorageAnchorage

FairbanksFairbanks

WrangelliaWrangellia

Peni

nsul

ar

Peni

nsul

ar

NFNF

DL/NFDL/NF

Kobu -k SouthForkFaultKobuk- SouthForkFault

AP-W-McAP-W-Mc

ALAL

A Terrane maps

TintinaFault

Fra

ser

Fau

ltF

rase

rF

ault

Rocky

Rocky

TrenchTrench

Mountain

Mountain

Queen

Charlotte

Fairw

eatherF

ault

Transition

Fault Co

astS

hear

Zo

ne

Co

astS

hear

Zo

ne

Fold&

Thrust Belt

Denali Fault

Denali Fault

Stikinia

Nah

anni

Fort

Sim

pson

Hot

tah

QN

QN

KO

MOMO

QN

CA

CA

CC

CC

WR

WR

AX

AX

YCHCH

SMSM

SMSMKOKO

NSNS

KOKO

OL CRCR PR

SC-FF

MT

CD

HA

BRBR

PACIFICPLATE

JUANDE FUCA

PLATE

Outer TerranesChugach

Crescent

Olympic

Pacific Rim

Prince William

Yakutat

Insular TerranesAlexander

Peninsular

Wrangellia

AX

WR

Y

CHCROLPR

Intermontane TerranesCache CreekQuesnelliaStikiniaWindy-Maclaren-

Bridge RiverCadwallader-MethowEaston & MelangeHarrison-Nooksack

Aurora Peak

CCQN

W

HA

BR

Alaskan TerranesAngayucham

KootenayYukon-Tanana

Koyukuk

Monashee

North Fork

Ruby

Slide Mountain

Tozitna

A

KO-YT

CA-MT NFNFR

SMT

Omineca & CentralAlaskan Terranes

Plutonics & UndividedMetamorphics

Seismic ProfilesReflection (used)

Reflection (not used)

R/WAR (used)

R/WAR (not used)

FaultsStrike-slip

Subduction

Thrust front?

NS

ContinentalNorth Slope (Foreland)

Brooks Range

Cassiar

Foreland Fold & Thrust Belt

Nisling

DisplacedContinental Margin

ContinentalProterozoic

Archean

North AmericanAncestral Basement

MO

WhitehorseWhitehorse

PrinceRupertPrinceRupert

CalgaryCalgary

EdmontonEdmonton

SeattleSeattle

0 500Distance (km)

RangeRange

North SlopeNorth Slope

Copper River Basin

FairbanksSE-NW SE-NW SE-NWS-N

B Alaskan Cordillera

7.87.55

7.88.28.2

6.7 6.67.1

6.7

4.05.04.0

6.4 6.26.2 5.86.2 5.2

6.56.55 6.56.5

6.06.0

TACTMid[Beaudoin et al., 1994]

TACTS[Fuis and Plafker, 1991; Fisher et al., 1989]

TACTOffshore[Brocher et al., 1994]

Peninsular Wrangellia Yukon-TananaChugach

OUTER TERRANES FORELANDINSULAR

Prince William

AleutianTrench

ContactFault

Border RangesFault System

West ForkFault System

DenaliFault

Beaver CreekFault

Victoria CreekFault

WickershamWhite Mtns

LM Tozitna

Schwatka

Ruby

Prospect Ck

T

Koyukuk

Brooks Range North Slope

Angayucham

Slate CreekTintina Fault Zone?

TozitnaFault

Kobuk-S.ForkFault

WisemanFault

ToyukFault

AtigunFault

Refraction velocityRefraction velocity

CENTRAL

FairbanksSE-NW SE-NW SE-NWS-N

AleutianTrench

ContactFault

Border RangesFault System

West ForkFault System

DenaliFault

Beaver CreekFault

Victoria CreekFault

TozitnaFault

Kobuk-S.ForkFault

WisemanFault

ToyukFault

AtigunFault

6.8

6.4

6.5 6.2 6.26.4

6.1

6.85

6.46.1

7.06.7 6.35

7.4

5.9 4.0 5.0 5.5

8.3 8.2

8.28.2 7.97.0

7.27.8

TACTN[Fuis et al., 1997; Wissinger et al., 1997]

1300 1400

Aleutian MegathrustInterface

W-E Offset300 km

?

?

?

?

?Pacific PlateLithospheric Mantle

Yakutat

Underthrust/Accreted?

North American (Alaskan) Lithospheric Mantle

Asthenosphere

epolShtroNIndentor

?120120

Interpretation1300 1400

1964 Mw9.2

[Brocher et al., 2004; Fisher et al., 2005]

C Northern Canadian Cordillera

SW-NE NW-SESW-NE W-E

Reflection fabricReflection fabric

0

8

16

24

32

Tim

e(s

)

[Cook et al., 1999][Cook et al., 2004; Evenchick et al., 2005][Cook et al., 2004; Evenchick et al., 2005][Morozov et al., 1998]

0

8

16

24

32

Tim

e(s)SNORCLE Line 1SNORCLE Line 2BSNORCLE Line 2AACCRETE

Refraction velocityRefraction velocity

[Spence and Asudeh, 1993; Dehler and Clowes, 1988]

[Morozov et al., 1998, 2001]

[Hammer et al., 2000]

[Hammer and Clowes, 2004] [Welford et al., 2001] [Fernandez-Viejo et al., 2003]

Tintina FaultKechika Fault Muskwa Anticlinorium W. Canada Sed. BasinStikine ArchBowser BasinCoast Shear ZoneQueen Charlotte Fault

Pacific OceanQ.C.

Islands Dease LakeWatson

LakeFort

NelsonNahanni

ButteHecate Strait Prince Rupert

Stewart

Queen CharlotteTraverse

ACCRETE

ACCRETE

SNORE Line 22 SNORE Line 21 SNORE Line 11

SW-NE SSW-NNE NW-SE W-E

S-N Offset(200 km)

PACIFIC INSULAR COAST BELT INTERMONTANE OMINECA FORELAND WOPMAY

Stikinia CCAX Coast Plutonic ComplexWrangelliaPacific Plate CA SM Cassiar KO-YT Nahanni Fort SimpsonFold and Thrust Belt

Asthenosphere

North AmericanAncestral Basement

Folded and imbricated crust includingNorth American ancestral basement

North American Lithospheric MantleNorth American Lithospheric Mantle

North American Lithospheric MantleNorth American Lithospheric Mantle

Pacific PlateLithospheric Mantle

Pacific PlateLithospheric Mantle

??

??

InterpretationInterpretation

Northern Cordillera Volcanic ProvinceHottah

D Southern Canadian Cordillera

N-SEN-WS E-WE-WE-WE-WSW-NE0

8

16

24

Tim

e(s

)

Reflection fabricReflection fabric

0

8

16

Tim

e(s)

85-3 85-9

51611-48 14 13 12 11 10 4 3 2 19 8 7

QN

Asthenosphere

Asthenosphere

North American Lithospheric Mantle

North American Lithospheric Mantle

Juan de Fuca

eltnaMcirehpsohtiL

WrangelliaJuan de Fuca Plate Plutonic Complex CD SBHAHA BR Quesnellia Kootenay Fold and Thrust BeltINSULAR COAST BELT INTERMONTANE OMINECA FORELAND CRATONPACIFIC

Rocky Mtn Trench Thrust & FoldBelt

Western CanadaSedimentary Basin

SLFVernonAntiform

Nicola HorstGaribaldi Volcanic Belt Fraser Fault

WCFMonashees Purcells RockiesOkanagan L.

120Interpretation

VancouverVancouver IslandSeamountRidge

Rocky Mtn Trench Thrust & FoldBelt

Western CanadaSedimentary Basin

SLFVernonAntiform

Nicola HorstFraser Fault

Monashees Purcells Rockies

AW

Wrangellia

E

C

C

North American Ancestral Basement

[Burianyk and Kanasewich, 1995][McLean and Spence, 1994][Zelt et al., 1993] [Zelt and White, 1995] [Chandra and Cumming, 1972][Drew and Clowes, 1990][Cudrak and Clowes, 1993]

6.0

7.9

5.0

8.38.0

8.28.0

5.85.86.1

6.46.5

6.26.2 6.26.66.6 6.5 6.3

8.06.66.6

7.2

Refraction velocityRefraction velocityN-S Offset

70 kmN-S Offset

60 kmS-N Offset

100 km

SW-NEVancouverVancouver Island

E-WEN-WS SW-NE W-E

SCoRE 7VISP Line PJSEISRIDG-85

[Cook et al., 1992]SC 1-12

[Varsek et al., 1993; Bustin et al., 2007, personal commun.]SC 13-16

120

7.8 8.0

85-1

SCoRE 3[Ramachandran et al., 2006]

SHIPS

[Hyndman et al., 1990]

[Clowes et al.,1987b]

[Clowes et al.,1987a]

[Rohr et al.,1988]

[Hasselgren & Clowes, 1995]

SCoRE 2 SCoRE 9

30 31

6.66.2

7.06.6

7.06.66.66.8

6.87.0 6.8

6.6

8.0

6.25.8

7.87.67.6 7.85

Teleseismic interpretations:continental Mohooceanic crustoceanic crust

[Nicholson et al., 2005][Nicholson et al., 2005][Bostock and Vandecar, 1995]

Active source interpretation:duplexed crust [Calvert et al., 2006]

Cascadia MegathrustInterface

?

?

?

W. Canada

7.8

dezinitnepreSMantle

dezinitnepreSMantle

E

[Lemieux et al., 2000]Alberta Basement

Geological Society of America Special Paper 433Whence the Mountains? Inquiries into the Evolution of Orogenic Systems: A Volume in Honor of Raymond A. PriceEdited by James W. Sears, Tekla A. Harms, and Carol A. Evenchick

From Chapter 5, “Lithospheric-scale structures across the Alaskan and Canadian Cordillera: Comparisons and tectonic implications,” by P.T.C. Hammer and R.M. Clowes

© 2007 The Geological Society of AmericaPrinted in the USA

Figure 2. Comparison of merged interpretations, seismic-refl ection profi les, and seismic velocity structure models for the southern Canadian Cordillera, northern Canadian Cordillera (Slave-Northern Cordillera Lithospheric Evolution [SNORCLE], ACCRETE, Queen Charlotte transects), and Alaskan Cordillera (Trans-Alaska Crustal Transect [TACT]) corridors, doi: 10.1130/2007.2433(05).F2. (A) Tectonic domain maps for the Alaskan and Canadian Cordillera with the location of the seismic-refl ection (red lines) and refraction (thick black lines) profi les used in the interpretations. Refl ection and refraction lines not incorporated in these composite profi les are shown by narrow gray and thick light-gray lines. Faults are indicated by solid and dashed thin black lines. (B–D) Composite interpretations and seismic models constructed for the three corridors. The primary tectonic domains crossed by the transect are indicated by the bar strip above each interpretation. Stippling above the crustal décollements indicates the complexity and uncertainty associated with the upthrust crust. In all of the panels, vertical exaggeration is 1:1. Direction headings note changes in the general orientation of the profi le. In the interpretation panels, solid navy lines indicate the interpreted location of wide-angle refl ectors. In the refl ection panels, thin red lines represent interpreted major refl ections, fabrics, and faults. The composite P-wave velocity model panels are presented using a common color scale. Velocities are also shown using numbers (km/s) and thin, dashed contour lines. The black lines represent interpreted wide-angle refl ector locations. The primary sources for the individual components of the compilation are noted below each panel. The red dashed line locates the modeled megathrust earthquake interface that represents the current plate boundary. For the southern Canadian Cordillera corridor (D), the blue dashed lines indicate boundaries determined by coincident teleseismic studies. Terrane abbreviations: A—Angayucham; AX—Alexander; BR—Bridge River; CA—Cassiar; CD-MT—Cadwallader-Methow; CC—Cache Creek; CF—Coldfoot; CH—Chugach; CR—Crescent; HA—Harrison; KO-YT—Kootenay-Yukon-Tanana; M—Manley; L—Livengood; MO—Monashee; NF—North Fork; NS—Nisling; OL—Olympic; PR—Pacifi c Rim; QN—Quesnellia; R—Ruby; SB—Spences Bridge; SM—Slide Mountain; T—Tozitna; W—Windy–Maclaren–Aurora Peak; WR—Wrangellia; Y—Yakutat. Other abbreviations: AW—accretionary wedge; C and E—refl ective bands; QCT—Queen Charlotte terrace; R/WAR—refraction/wide-angle refl ection; SC—Southern Cordillera; SCoRE—Southern Cordillera Refraction Experiment; SHIPS—Seismic Hazards in Puget Sound; SLF—Slocan Lake fault; SNORE—SNORCLE Refraction Experiment; VISP—Vancouver Island Seismic Profi le; WCF—West Coast fault.