Wouter Bleeker, Richard Ernst & Ken Buchan Geological Survey of Canada, Ottawa

Penrose, June 2006 1

Did Plate Tectonics begin in Paleoproterozoic Did Plate Tectonics begin in Paleoproterozoic

time?time?

…well before, but scale & style become more …well before, but scale & style become more

modernmodern

during the Paleoproterozoicduring the Paleoproterozoic

Wouter Bleeker, Richard Ernst & Ken Wouter Bleeker, Richard Ernst & Ken BuchanBuchan

Geological Survey of Canada, OttawaGeological Survey of Canada, Ottawa

GE

OLOGICAL

SU

RVEY C O M MIS

SION

GÉOLOGIQ

UE

Evidence for plate behaviour at 2.1-Evidence for plate behaviour at 2.1-1.8 Ga:1.8 Ga:

break-up, dispersal & suturingbreak-up, dispersal & suturingof Archean cratonsof Archean cratons

Evidence for plate behaviour at 2.1-Evidence for plate behaviour at 2.1-1.8 Ga:1.8 Ga:

break-up, dispersal & suturingbreak-up, dispersal & suturingof Archean cratonsof Archean cratons


0

100

200

300

400

500

600

700

800

050010001500200025003000350040004500

Age (Ma)

Constant event count model

Actual event count per 100 Ma

No data

Bleeker & Enst, in prep.

Significant secular change?...Yes, Significant secular change?...Yes, of course!of course!Significant secular change?...Yes, Significant secular change?...Yes, of course!of course!•Higher heat productionHigher heat production•Weaker lower crustWeaker lower crust•Always more basalt in the system …more significant Always more basalt in the system …more significant

density inversionsdensity inversions•Smaller plate scalesSmaller plate scales•Faster recyclingFaster recycling

“The 2.7 Event”


Precambrian geology of North AmericaPrecambrian geology of North AmericaPrecambrian geology of North AmericaPrecambrian geology of North America

Modified after Hoffman, 1989 ; based on a century of geological research

A A

Paleoproterzoic Paleoproterzoic

collage of collage of

micro-plates and micro-plates and

inter-vening inter-vening

arcs terranesarcs terranes



Great Slave Lake Shear Zone

7. Large strike-slip faults?7. Large strike-slip faults? …Yes.…Yes.7. Large strike-slip faults?7. Large strike-slip faults? …Yes.…Yes.

The ~1.8 Ga collage: plate The ~1.8 Ga collage: plate tectonics?tectonics?

The ~1.8 Ga collage: plate The ~1.8 Ga collage: plate tectonics?tectonics?

LITHOPROBE’SSNORCLE Transect

Relevant questions:Relevant questions:1.1. Was there significant lateral movement? Was there significant lateral movement? ...Yes....Yes.

2.2. Are now adjacent blocks unrelated (exotic)?Are now adjacent blocks unrelated (exotic)? ...Yes, ...Yes, commonly.commonly.

3.3. Plate behaviour: rifting, break-up, convergence?Plate behaviour: rifting, break-up, convergence?...Yes....Yes.

4.4. Did blocks behave (quasi) rigid?Did blocks behave (quasi) rigid? ...Yes, some....Yes, some.

5.5. Strong asymmetry across suturing orogens?Strong asymmetry across suturing orogens? ...Yes....Yes.

6.6. Are time spans and rates similar?Are time spans and rates similar? …Yes, …Yes, comparable.comparable.

Relevant questions:Relevant questions:1.1. Was there significant lateral movement? Was there significant lateral movement? ...Yes....Yes.

2.2. Are now adjacent blocks unrelated (exotic)?Are now adjacent blocks unrelated (exotic)? ...Yes, ...Yes, commonly.commonly.

3.3. Plate behaviour: rifting, break-up, convergence?Plate behaviour: rifting, break-up, convergence?...Yes....Yes.

4.4. Did blocks behave (quasi) rigid?Did blocks behave (quasi) rigid? ...Yes, some....Yes, some.

5.5. Strong asymmetry across suturing orogens?Strong asymmetry across suturing orogens? ...Yes....Yes.

6.6. Are time spans and rates similar?Are time spans and rates similar? …Yes, …Yes, comparable.comparable.


WB '99

100 km

0

20

20

40

40

100

Wopm ayFault

Yellowknife RiverFault Zone

CameronRiver Belt

BurwashFormation

Yellowknife BeltRussel LakeBelt

BeaulieuRiver Belt

Loop LakeBelt

CourageousLake Belt Lac de Gras

kimberlites

GeorgeLake

>3.0 Ga lower

crustal xenoliths

Back RiverVolcanic Com plex

Beaulieu RiverFault Zone

BathurstFault System

AntonComplex

CoronationSupergroup

Sleepy DragonComplex

Jolly LakeComplex

2.69 Ga suture orattenuated margin?

Lac de GrasStructural Basin

YellowknifeStructural Basin

Back RiverCulmination

Malley RapidsAnticlinorium

Hackett RiverGneiss Dome

GoulburnSupergroup

ENEENEWSW

Hackett RiverSyncline

Great BearMagmatic Zone

WopmayFront

Kilihigok BasinBear Province (Wopmay Orogen) Slave Province

Thelon Front

Churchill ProvincePalaeoproterozoic (2.0-1.8 Ga)Palaeoproterozoic (2.0-1.8 Ga) Hadean to Archaean (4.05-2.58 Ga)

Realm of the Central Slave Basement Complex: central and western parts of craton Eastern Slave Domain::Palaeoproterozoic with reworked Archaean

Archaean to Palaeoproterozoic

Central Slave Basement Complex

Ultra-depleted harzburgite

Eastern Slave Domain

Indin Lake-

West BayFault System

Poorly known basem ent of H ottah Terrane

Central Slave Basem ent Com plex (4.05-2.82 G a)Poorly defined basem ent of the eastern Slave craton,

isotopically 2.85 Ga£Poorly defined basement ofthe w esternmost Slave craton

Proterozoic, brittle strike-slip fault system,

sinistral, overprinting western margin of the

craton (Indin-West Bay Fault System)

Proterozoic frontal

thrusts

Proterozoic gabbrosills, causing bright

reflections (Y1) east

of Yellowknife

Form surface traces

outlining fold structures

Form surface traces

outlining fold structuresVertical strike-slip faults

Bear Creek G roup Churchill Province (Rae craton)

basement, reworkedG reat Bear Magmatic Zone plutonic rocks (1.86-1.84 G a)

Central Slave C over G roup: conglomerate, quartzite, banded iron formation

O verall younging direction of cover sequence

Peacock Hills and

Kuuvik FormationsHigh-grade cover rocksG reat Bear Magmatic Zone volcanic rocks (1.86-1.84 G a)

Kam G roup and correlatives: mafic volcanic rocks, minor rhyolites (2.73-2.70 G a) Mafic to intermediate volcanic rocks (ca. 2.71-2.70 G a)

Ellice Formation

Reworked Slave Province metavolcanic rocks

and metagreywackes, kyanite bearing close to front

Churchill Province granitoids

Churchill Province granitoids

Coronation Supergroup (2.0-1.86 G a):

Snare and Epworth groups

Banting G roup and correlatives (2.69-2.66 Ga)

Syn-Banting Group subvolcanic plutons (2.69-2.66 G a)

Syn-Kam G roup subvolcanic plutons (2.73-2.70 Ga)

Hidden and Duckfish lake plutons, Yellowknife area (ca. 2.61 Ga)

Defeat Suite plutons: diorite, tonalite, granodiorite (ca. 2.63-2.62 Ma, post-date D1)

Burw ash Formation and correlatives:

turbiditic greyw ackes (2.68-2.64 Ga)

Late-tectonic conglomerates in asymmetric, fault-bounded panels (2.60-2.58 G a),

e.g. along Yellowknife River Fault Zone and Beaulieu R iver Fault Zone

Crustally derived, anatectic granitoid sheets and batholiths, andpresumed source regions (2.60-2.58 G a, syn-kinematic with D 2 and D3)

??

Pb Nd

??

Pb Nd

??

Pb Nd

??

Pb Nd

??

Pb Nd

??

Pb Nd

??

Pb Nd

??

Pb Nd

??

Pb Nd

??

Pb Nd

??

Pb Nd

??

Pb Nd

Bleeker, 2002

Cook et al., 1999


Accretionary structure along westernAccretionary structure along westernmargin of Slave craton, 1.9-1.7 Ga:margin of Slave craton, 1.9-1.7 Ga:Accretionary structure along westernAccretionary structure along westernmargin of Slave craton, 1.9-1.7 Ga:margin of Slave craton, 1.9-1.7 Ga:

Cook et al., 1999


SuccessiSuccessivevesutures:sutures:

SuccessiSuccessivevesutures:sutures:


Suture Suture geometries:geometries:Suture Suture geometries:geometries:

e.g., White et al., 2002


A

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ppalac

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Yavap

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Mazatza

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C etn ra l Pla ins

O rog en

Sr-is

otope lin

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ledides

In n ui tian

Pen

okean

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?

??

?

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??

?

? ?

Htotah

Nuna Sv

n

eco

fe

nian

K

n

etilidi

a

Yavapai

Baltica

Siberia?

Australia-Antarctica?

???

???

???

Laurentia withinLaurentia within~1.8 Ga “Nuna”:~1.8 Ga “Nuna”:Laurentia withinLaurentia within~1.8 Ga “Nuna”:~1.8 Ga “Nuna”:

e.g., Buchan et al., 2000

Long-livedactive margin


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In n ui tian

Pen

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Htotah

Nuna Sv

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eco

fe

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K

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Yavapai

Nuna to Rodinia:Nuna to Rodinia:Nuna to Rodinia:Nuna to Rodinia:


A

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ppalacians

Yavapai

Mazatz

a l

C e tn ra l Pla ins

Orog en

Sr-iso

tope line

C

n

ao

ledides

In n ui tian

Peno

kean

?

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??

?

?

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??

?

? ?

Htotah

RodiniaSv

n

eco

fe

nian

K

n

etilid

ia

Yavapai

Grenville

~1 Ga Rodinia (conceptual only):~1 Ga Rodinia (conceptual only):~1 Ga Rodinia (conceptual only):~1 Ga Rodinia (conceptual only):

Rifted Nunafragments

Intact core of~1.8 Ga Nuna

Stray fragments


Acasta

Isua

1000 km

(approx. scale)

rifted margin

rifted margin rif

ted margin

Laurentia“North American craton”

Bleeker, 2005

Further back in time: before NunaFurther back in time: before NunaFurther back in time: before NunaFurther back in time: before Nuna


Ancestral landmass“Superia”

““Break-out” of the Superior craton,Break-out” of the Superior craton,out of ancestral landmass Superia:out of ancestral landmass Superia:““Break-out” of the Superior craton,Break-out” of the Superior craton,out of ancestral landmass Superia:out of ancestral landmass Superia:

Superior craton

2505 Ma(Mistassini)

2450 Ma(Matachewan)

2210-2220 Ma(Ungava)

(Biscotasing)2170 Ma

(Marathon)2110 Ma(Fort Francis)

2080 Ma

(Minto)2000 Ma

(Molson)1883 Ma

KareliaHearne

Wyoming

Kola

Others

Others

Others


Superior

HearneHearne

KareliaKarelia3.5 Ga crust in Hearneand Karelia cratons

2505 Ma(Mistassini)

Superior

2450 Ma

Nipissing sills (N) in Superiorand Karjalitic sills (K) in Karelia,ca. 2220-2200 Ma

Koli sill


(Marathon)2110 Ma

Hurwitz Gabbrosills (H), 2110 Ma

Layeredintrusions:2.50 Ga

2.45-2.48 Ga

Kola

Burakovsky(2449±2 Ma)

??

??

??

“greater Karelia”craton inlcudingKola Peninsula?

Re-entrant fromwhich Wyomingcraton originated

Superia

Wyoming

Superia:Superia:Superia:Superia:

Bleeker & Ernst, 2006


Superior

HearneHearne

KareliaKarelia

2505 Ma(Mistassini)

Superior

2450 Ma

Koli sill


(Marathon)2110 Ma

Hurwitz Gabbrosills (H), 2110 Ma

Correlating multiple events:Correlating multiple events:Correlating multiple events:Correlating multiple events:

Bleeker & Ernst, 2006


A

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Yavap

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Mazatza

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C etn ra l Pla ins

O rog en

Sr-is

otope lin

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C

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ledides

In n ui tian

Pen

okean

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??

?

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??

?

? ?

Htotah

Nuna Sv

n

eco

fe

nian

K

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etilidi

a

Yavapai

From late Archean supercratons to From late Archean supercratons to Nuna:Nuna:break-up & independent drift ofbreak-up & independent drift ofcratonic fragmentscratonic fragments

From late Archean supercratons to From late Archean supercratons to Nuna:Nuna:break-up & independent drift ofbreak-up & independent drift ofcratonic fragmentscratonic fragments

Not to scale!


30 0

30 0

60 0

90 0

90 0

60 0

EQ

2.22.12.01.91.7 1.8 2.5 2.62.42.3

2.45 Ga

2.00 Ga

1.88 Ga

1.74 Ga2.12 Ga

2.17 Ga

2.08 Ga

2.19 Ga

2.22 Ga

alternatepolarity

supercraton break-up

supercratonformation

alternatepolarity

HudsonianOrogeny

Time (Ga)

Did things Did things move?move?

Did things Did things move?move?

Eq

60

30

Minto1998 +/-2

Nipissing N12217 +/-4

Senneterre2216 +8/-4

Matachewan E

Matachewan W2473-2446

Biscotasing E 2167 +/-2

Cleaver1740 +5/-4

Biscotasing W ca. 2170

Lac Esprit2069 +/-1

Ft. Frances 2076+5/-4

Cauchon Lake 2091+/-2

Maguire~2230

Molson~1880

Ptarmigan? 2505 +/-2

Mistassini? 2510-2500

Marathon R2101+/-2

Marathon N ca. 2121

eastern SuperiorProvince paleopole

western SuperiorProvince paleopole

Laurentia paleopole

PALEOPOLES

~5 cm/yr


Ophiolites? Sparse but Ophiolites? Sparse but present!!present!!

Ophiolites? Sparse but Ophiolites? Sparse but present!!present!!

Kontinen,Peltonen et al.


Diagnostic rock associations:Diagnostic rock associations:Diagnostic rock associations:Diagnostic rock associations:

-Plume-assisted extension & break-up?-Plume-assisted extension & break-up? …Yes, …Yes, definitely.definitely.

-Rift & passive margin sequences?-Rift & passive margin sequences? …Yes.…Yes.



Slave basement

Passive margin sequence

Rift sequence

Foredeep sequenceArc


Diagnostic rock associations:Diagnostic rock associations:Diagnostic rock associations:Diagnostic rock associations:



-Arcs? Arc batholiths (at plate scale)?-Arcs? Arc batholiths (at plate scale)? …Yes.…Yes.

-Ophiolites?-Ophiolites? …Yes.…Yes.

-Elevated P/T metamorphic facies series?-Elevated P/T metamorphic facies series? …Yes,…Yes,…but UHP??…but UHP??

-Blueschists-Blueschists …No…or?…No…or?



-Arcs? Arc batholiths (at plate scale)?-Arcs? Arc batholiths (at plate scale)? …Yes.…Yes.

-Ophiolites?-Ophiolites? …Yes.…Yes.

-Elevated P/T metamorphic facies series?-Elevated P/T metamorphic facies series? …Yes,…Yes,…but UHP??…but UHP??

-Blueschists-Blueschists …No…or?…No…or?


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In n ui tian

Pen

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Htotah

Nuna Sv

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eco

fe

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K

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Yavapai

Conclusions:Conclusions:The Paleoproterozoic preserves a The Paleoproterozoic preserves a clear record of (small) plate clear record of (small) plate tectonics, resulting in Earth’s tectonics, resulting in Earth’s first “modern” supercontinent Nunafirst “modern” supercontinent Nuna

Conclusions:Conclusions:The Paleoproterozoic preserves a The Paleoproterozoic preserves a clear record of (small) plate clear record of (small) plate tectonics, resulting in Earth’s tectonics, resulting in Earth’s first “modern” supercontinent Nunafirst “modern” supercontinent Nuna

Not to scale!



Matachewan dykesMatachewan dykes

2446 Ma (2.45-2.5 Ga)2446 Ma (2.45-2.5 Ga)

Hearne – southern Superior link: 2446 Ma Hearne – southern Superior link: 2446 Ma dykesdykesHearne – southern Superior link: 2446 Ma Hearne – southern Superior link: 2446 Ma dykesdykes

2440-2450 Ma (2.45-2.5 Ga)2440-2450 Ma (2.45-2.5 Ga)

Kaminak dykesKaminak dykes

Dates by Heaman


300

300

600S

600N

EquatorH

H

S SH

Hearne Superior Superior-Hearneca. 2446 Ma 2.45 Ga2.45 Ga

a cb

30 N0

d

Bleeker, 2002, 2004

2110 Ma

Solution allowed by current paleomagnetic Solution allowed by current paleomagnetic data:data:Solution allowed by current paleomagnetic Solution allowed by current paleomagnetic data:data:

Penrose, June 2006 26Bleeker & Ernst, 2006

BarcodesBarcodes::BarcodesBarcodes::


Kaapvaal Slave SuperiorLew.Nain

Labr. KareliaHearne

SuperiaSclavia

Vaalbara

““Fragmentation tree”Fragmentation tree”of Archean fragmentsof Archean fragments““Fragmentation tree”Fragmentation tree”of Archean fragmentsof Archean fragments

The Archean family The Archean family treetree


“Evidence for plate behaviour at 2.1-1.8 Ga: break-up, dispersal, and suturing of Archean cratons”

Wouter Bleeker & Richard Ernst

Presentation style: oral is preferred.

I will trace the origin of Archean cratons within the context of much larger supercratons in the late Archean. These may or may not have been connected in a ca. 2.6 Ga supercontinent. The mininum length scale of supercratonic landmasses was many thousands of kilometres. Whatever the details, fundamental heterogeneity of Archean cratons demands that horizontal movements and terrane juxtaposition must have played a major role in building supercratonic aggregations.

Following emplacement of numerous LIPs, and their plumbing systems, the supercratonic landmasses broke up diachronously between ca. 2.2 Ga and 1.9 Ga, spawning most of the ca. 35 known Archean cratons (s.s.). After a dispersal phase, these cratonic fragments and intervening juvenile terranes aggregated and collided between 1.9 and 1.8 Ga to form Earth’s first “modern” supercontinent Nuna (a.k.a. Columbia).

I call Nuna the fist “modern” supercontinent because its geodynamics and tectonics show mostly familiar aspects (e.g., incorporation of sediment-rich passive margins, the first bonafide ophiolites, large coherent arcs, and undisputed sutures). Also, it was large enough to start dominating, for the first time, geochemical cycles with continental signatures (e.g., the seawater Sr isotopic record). The only major “tectonic innovation” yet to come were blueschists.

From 1.8 Ga to ca. 1.0 Ga, Nuna evolved into Rodinia. Details remain murky but general systematics suggest themselves.

Going back in time, component Archean cratons within 1.8 Ga Nuna can be restored into their ancestral supercratonic aggregations. We show that there is enough information in the system to do so for many of the ca. 35 cratons. In fact, a concerted international effort could accomplish this in less than a decade. Only then will we be able to test whether late Archean supercratons were ever connected in a pre-Nuna supercontinent and make general statements about the early part of the supercontinent cycle.

Wouter Bleeker, Richard Ernst & Ken Buchan Geological Survey of Canada, Ottawa

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