tp 11 ciclo wilson 2013 4

8/12/2019 Tp 11 Ciclo Wilson 2013 4

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8/12/2019 Tp 11 Ciclo Wilson 2013 4


Etapa A - Cratón Estable.

-Continente erosionado al nivel del mar, equilibrio

CICLO DE WILSON

.

- No hay terremotos o actividad volcánica, por

decenas a cientos de millones de años.

Etapa B - Hot Spot / rifting.

-Inicio punto caliente con pluma de magma

primitivo en la base del continente,- ,

un gran domo seguido por fallamiento normal y

rifting.

Etapa C - Margen divergente temprana, Creación

de Nueva Corteza Oceánica Corteza

- Una serie de puntos calientes pueden unirse y

.

- Rifting forma una nueva cuenca oceánica: con

producción de volcanismo,

- Rocas ígneas máficas primitivos (basalto ygabro)

Etapa D - Margen divergente completo.

-

Central, dorsales oceánicas, margen continental

pasivo.

Etapa E - Creación de un límite convergente: arco de islas volcánicas

- Inicia Ciclo de Wilson Convergencia, creación de un nuevo límite de placas, subducción,

cierre de cuenca oceánica, corteza oceánica se rompe en algún sitio y comienza a descender

hacia el manto por diferencia de densidad con la corteza continental

Etapa F - colisión continente / Isla Arco

-Colisión continente/arco islas, sutura, cierra zona

, .

Etapa G – Orógeno subduccion Cort Oc/Contin

- , , ,

esquistos azules, frente volcánico, antearco,

retroarco, desarrollo de grandes fallas inversas

(FPC) hasta formar altas montañas.

- Desarrollo de Arco Volcánico, reciclado de

magmas, engrosamiento corteza, cristalización,contaminación de magmas de andesitas dacitas y

, .

- Desarrollo de backarc-basin y complejos de

subducción, .

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Etapa H - Orógeno Continente / Continente

-Cierre océano remanente, colisión continente / continente.

- .

- Sedimentos se depositan en una cuenca antepaís.

Etapa I – Craton estable Continental

-Montañas erosionadas sierras ba as.

- Desarrollo de penillanura .

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Interpretacion Tectonica:

1. Cuántas asociaciones petrotectónicas se pueden identificar?

2. Qué indica la asociación de metabasitas y esquistos glaucofánicos ?

3. Que indican la variación del grado metamórfico de los complejos precámbricos?

4. Existen evidencias de algún terreno alóctono?; de ser así, indicar:

a. cuales son esas evidencias,

b. cual sería el terreno aloctono.

5. Qué inferiría de las secuencias plegadas y corridas de edad silúrico-devónicas?

6. Que relación existe entre la anomalía de Bouguer observada (AB) y los sismos?

7. Qué causas pueden tener los sismos del sector oriental, y que indican?

8. Existen evidencias de regímenes de subducción?; de ser así, indicar:

a. Cuántos regimenes reconoce,

b. ue características resentan.

9. Existen ciclos orogénicos, de ser así, indicar:

a. cuántos ciclos reconoce,

b. ue características son las ue los identifican?.

10. Sobre la base de perfiles y/o cortes esquemáticos, reconstruya la evolución geológica de

la región en estudio.

A Simple Wilson CycleThe Opening and Closing of An Ocean Basin

A more complete version of the Wilson cycle is available at:

http://geollab.jmu.edu/Fichter/Wilson/Wilson.html

• The WilsonWilson cyclecycle begins in StageStage AA with a stable

continental craton. A hot spot (not present in the

drawings) rises up under the craton, heating it, causing it

, , ,

finally split into two pieces. This process not only splitsa continent in two it also creates a new divergent plate

boundary.

• -

two continents, east and west, and a new ocean basin

(the ophiolite suite) is generated between them. The

ocean basin in this stage is comparable to the Red Sea

toda As the ocean basin widens the stretched and .

thinned edges where the two continents used to be

joined cool, become denser, and sink below sea level.

Wedges of divergent continental margins sediments

.

• StageStage CC - the ocean basin widens, sometimes to

thousands of miles; this is comparable to the Atlanticocean today. As long as the ocean basin is opening we

are still in the o enin hase of the Wilson c cle..

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• Stage DStage D - the closing phase of the Wilson Cycle begins

when a subduction zone (new convergent plate boundary)

forms. The subduction zone may form anywhere in the

, .

we take the simplest situation; a subduction zone

developing under the edge of one continent. Once the

subduction zone is active the ocean basin is doomed; it

.

remnant ocean basins.

• Stage EStage E - most of the remnant ocean basin has subducted

and the two continents are about to collide. Subduction

.

the subduction zone igneous magma is generated and rises

to the surface to form volcanoes, that build into a

cordilleran mountain range (e.g. the Cascade mountains of

, , . ,

of metamorphism occurs and folding and faulting.

• Stage FStage F - the two continents, separated in Stages A and

B now collide. The remnant ocean basin is completely

.

cycle is over. Because the subduction zone acts as a ramp

the continent with the subduction zone (a hinterland)

slides up over the edge of the continent without out it (a

.

•• Stage GStage G - once the collision has occurred the only thing left for the mountain to do is erode down to sea level - a

peneplain. The stage G drawing is a distortion, however. With the collision the continental thickness doubles, and

since continental rock is light weight, both will rise as the mountain erodes, much like a boat rises when cargo is

. , , ,

eventually get back to the earth's surface again.

• No rock is accidental. No rock is accidental. No idea in geology is more profound than

e yc ca pen ng an os ng oe yc ca pen ng an os ng o

Ocean BasinsOcean Basins

t s; t runs rom t e center to t e w o e o geo ogy an n uences

every subdiscipline of the field. Genuine understanding of the

science of geology begins with one's ability to understand and

explain why no rock is accidental.

• Tectonics is concerned with deformation in the earth and the

forces which produce deformation. Plate tectonics is the theory thatthe earth's lithosphere (outer rigid shell) is composed of several

dozen "plates", or pieces, which float on a ductile mantle, like slabs

of ice on a pond. In plate tectonic theory earth history, at its

,

new ocean basins being born, followed by motion reversal,

convergence back together, plate collision, and mountain building.

This cycle of opening and closing ocean basins is the Wilson

Cycle.

• a e ec on cs s one o e grea un y ng eor es n geo ogy.

Virtually every part of the earth's crust, and every kind of rock and

every kind of geology can be related to the plate tectonic

conditions which existed at the time they formed. Nothing in

geology makes sense except in terms of plate tectonic theory.

• One of the most important messages of modern understanding of

plate tectonics and the Wilson cycle is that beginning with a parentigneous rock of mafic/ultramafic composition all the other rocks

now on the earth can be generated. The most important message of

the late tectonic rockc cle isthateach andever rockforms onl

under a specific set of tectonic conditions.Version completa del Wilson cycleWilson cycle at:

http://csmres.jmu.edu/geollab/fichter/Wilson/Wilson.html

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• Most geologic activity occurs at the three kinds of

plate boundaries:

(1)(1) divergent boundariesdivergent boundaries where plates are moving

apart and new crust is being created,

(2)(2) convergent boundariesconvergent boundaries where plates are moving

together and crust is being destroyed, and

(3)(3) transform boundariestransform boundaries where plates slide past

one another.

Very interesting geology occurs along transformboundaries, as all the faulting along the San Andreas

fault system in California attests to, but this model

does not include transform boundaries.

• Sta e A:A Stable Continental Craton.

• Stage B: Hot Spot and Rifting

• Stage C: Creation of New Oceanic Crust: Early Divergent Margin

• Stage D: Full Divergent Margin

• Sta e E: Creatin a Conver ent Boundar : Volcanic Island Arc

Mountain Building

• Stage F: Island Arc-Continent Collision Mountain Building

• Stage G: Cordilleran Mountain Building

• Stage H: Continent-Continent Collision Mountain Building

• Stage I: Stable Continental Craton

Version completa del Wilson cycleWilson cycle at:

http://csmres.jmu.edu/geollab/fichter/Wilson/Wilson.html

tp 11 ciclo wilson 2013 4

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