The Wilson Cycle
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The Wilson Cycle Supercontinent cyclisity?. The Wilson Cycle: named after J. Tuzo Wilson, one of the founding fathers of platetectonics and discoverers of transform faults. Wilson used his old reference background, in the North Atlantic realm

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The Wilson Cycle Supercontinent cyclisity?

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The wilson cycle supercontinent cyclisity

The Wilson Cycle

Supercontinent cyclisity?

The Wilson Cycle: named after J. Tuzo Wilson, one of the

founding fathers of platetectonics and discoverers of transform faults.

Wilson used his old reference background, in the North Atlantic realm

and the Appalachian - Caledonian orogenic belts on both sides of the

Atlantic ocean to formulate a hypothesis saying that the building of

mountain belts have a close relationship to the opening and closure

of oceans with oceanic lithosphere.

Hence he introduced the term ”the Proto-Atlantic” as a name for the

postulated ocean that according to the model once opened and closed

to produce the Appalachians and the Caledonides


The wilson cycle supercontinent cyclisity

5) Remnant stage

Continental collision, suture zones, deform-

ation and metamorphism, mountain building

Extensional collapse, faulting and collapse

basins

4) Terminal stage

Near closure of ocean, mature arcs and

back-arc, accreationary wedges, HP-LT

metamorphic complexes

(Mediterranean See area)

3) Vaning stage: Intra-oceanic subduction

and island arcs transition to Andean margins.

(SE Asia and Western Passific)

2) Mature stage Passive margins with large

shelf-areas (Atlantic Ocean)

1) Embryonic to Young stage.

Rifts to small ocean basin with sea-floor

spreading. (East African rift and Red Sea)


The wilson cycle supercontinent cyclisity

Traditional Wilson cycle model:

Orthogonal opening and closure like on the previous

slide, two-dimentional models.

Modified Wilson cycle model:

Wilson-cycle type tectonics with a modern

approach;---one ocean opening--- another closing,

cf. Indian ocean opening -- eastern Tethyan closing.


The wilson cycle supercontinent cyclisity

Notice that traditional

Wilson-cycle tectonics

does not work to explain

formation of the

Caledonides


The wilson cycle supercontinent cyclisity

Supercontinent cyclisity?

From Rodinia to Pangea?? Does the earth´s continental lithospheric

plates assemble and rift apart in longer term cycles?

≈ 500 myr.

cycle?


The wilson cycle supercontinent cyclisity

  • TERRANE ANALYSES

  • Type of tectonic analyses that focusses on differences

  • rather than similarities between geological units.

  • First used in the North American Cordillereas

  • Differences in:

  • Stratigraphic record

  • Basement

  • Deformation/metamorphic histories

  • Fauna zonation and provinciality

  • Geophysical signature

  • Apparent Polar Wander Paths


The wilson cycle supercontinent cyclisity

SUSPECT TERRANES: TECTONOSTRATIGRAPHIC

TERRANES THAT HAVE UNSETTLED AFFINITY/

ORIGIN WITH RESPECT TO THE CONTINENT WHERE

IT ENDS UP AFTER AN OROGENY

EXOTIC TERRANES: TECTONOSTRATIGRAPHIC

TERRANES THAT HAVE OUTBOARD ORIGIN WITH

RESPECT TO THE CONTINENT WHERE IT ENDS UP

AFTER AN OROGENY. EXAMPLES OPHIOLITES AND ISLAND ARC

COMPLEXES, CONTINETAL FRAGMENTS WITH AN ORIGIN IN ANOTHER

CONTINENT


The wilson cycle supercontinent cyclisity

Terranes (terreng konseptet):

A terrane is defined as a regionally mapable geological unit, limited

by faults, and with a geological history/evloution/signature that

makes it distinct from surrounding units.

4 main types of terranes (NB! written terrane and not terrain):

Stratigraphic terrane: characterised by a similar stratigraphic

sequence including units of continental/oceanic crust

Fragmented/broken terranes: characterised by blocks of

variable sizes, lithologies and ages engulfed in a deformed

composite matrix (suture zones and melanges)

Composite terranes. characterised by being composed of 2 or

more terranes, which from a particular point in time share the

same geological evolution across previous terrane boundaries

Metamorphic terranes: characterised by a penetrative

metamorphic textures/structures, so that possible previous

tectonic distinctions have been destroyed


The wilson cycle supercontinent cyclisity

Composite terrane C

A

B

Linking of terranes:

Terrane linking unconformities

”Stitching” plutons, the two terranes

A and B were together at the time the

pluton C was intruded, in this case

this happened before

the unconformity

since the pluton is overlain

by the sediments

Composite terrane D

A

B

C


The wilson cycle supercontinent cyclisity

Terrane analysis,

Canadian Applachians


The wilson cycle supercontinent cyclisity

Terrane map of the

North American

Cordilleras

(After Jones et al. 1982)

Notice the wide distribution of the

terrane shown in red ”Wrangelia”

The collage of terranes reflects the

progressive accreation of suspect and

exotic elements originating further to

the south. Notice that Baia California

will be detached from the continent and

with time end up in Alaska region


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