The birth and death of plate boundaries

[kingwinner]

"The Birth and Death of Plate Boundaries:

The following processes can form new plate boundaries:

a. continental rifting

b. continental collisions "

(quoting from notes)

 

I truly understand how "continental rifting" can form new plate boundaries, but how can "continental collisions" form new plate boundaries?

 

Furthermore, the above only explains the "birth" part........how can continental rifting and continetal collisions give "death" to plate boundaries?

 

Awaiting for your favorable reply! ;)

[nkt]

A collision can cause the plates to shatter or splinter, and so create a large number of smaller plates around existing faults.

 

Death would presumably occur when a plate was totally subsumed.

 

I'm not an expert on plate tectonics, though.

[kingwinner]

deleted due to overlapping

[kingwinner]

But why the continental collision, like between India and Asia, did not create any new plate boundaries?

 

How can "death" of a plate boundary occur with continental rifting and continental collisions? They won't subduct or be subducted and so the continental plates won't be consumed...

 

Continental Rifting give birth to (form) new plate boundaries-I understand this! Continental rifting will spilt a plate into two, creating a new plate boundary

Continental Collision give birth to (form) new plate boundaries-I don't get how this can happen

Continental Rifting give death to (destroy?) plate boundaries-I don't get how this can happen

Continental Collision give death to (destroy?) plate boundaries-I don't get how this can happen

 

[The bad thing is that when I seearch the web for "the birth and death of plate boundareis", there is nothing good that matches...] :rolleyes:

[Turtle]

Continental Collision give birth to (form) new plate boundaries-I don't get how this can happen

Continental Rifting give death to (destroy?) plate boundaries-I don't get how this can happen

Continental Collision give death to (destroy?) plate boundaries-I don't get how this can happen

 

[The bad thing is that when I seearch the web for "the birth and death of plate boundareis", there is nothing good that matches...] :hihi:

 

___Frankly Kingwinner, I don't understand what they refer to here either :) ; I suggest asking the instructor for specific examples on Earth of these described situations. :rolleyes:

[kingwinner]

"The BIRTH and DEATH of Plate Boundaries:

The following processes can form new plate boundaries:

a. continental rifting

b. continental collisions

 

Continental Rifting

Divergent boundaries are formed when a continent splits into two in a process known as continental rifting.

-lithosphere stretches until the fomration of a lower area

-the asthenosphere rises because of less compression, causing partial melting and fomration of volcanoes

-if continent splits completely, a mid-oceanic ridge will form and seafloor spreading occurs

-e.g. East African Rift

 

Collision

-subduction of oceanic plates between two continents, e.g. between India and Asia

-formation of the Himalayan mountains, crust also becomes thincker"

 

============================================

 

This is the whole note! If nobody understands (neither do I), I would have to ask the instructor next Monday (hopefully not too late...a test is coming up)

[Turtle]

___Ok, here is what I get from this. In the lower diagram see that the Ancient Oceanic Crust is now no longer in contact with the Indian Plate, therefore the implication that no "boundary" between the 2 exists? There is still a plate boundary there, but now it is a boundary between the Indian Plate & the Eurasian Plate. In their terms, the plate boundary between the Ancient Oceanic Crust & the Indian Plate has died.

 

Grindingly Yours,

Turtle :rolleyes:

[kingwinner]

___Ok, here is what I get from this. In the lower diagram see that the Ancient Oceanic Crust is now no longer in contact with the Indian Plate, therefore the implication that no "boundary" between the 2 exists? There is still a plate boundary there, but now it is a boundary between the Indian Plate & the Eurasian Plate. In their terms, the plate boundary between the Ancient Oceanic Crust & the Indian Plate has died.

 

Grindingly Yours,

Turtle :)

Oh, I see! So 2 plate boundaries become 1 single plate boundary at that place...

 

But at the top it says continental collisions form new plate boundaries...really weird... :rolleyes:

 

"The following processes can FORM( :hihi: ) new plate boundaries:

a. continental rifting

b. continental collisions"

[Turtle]

Oh, I see! So 2 plate boundaries become 1 single plate boundary at that place...

 

But at the top it says continental collisions form new plate boundaries...really weird... :rolleyes:

___The boundary between colliding Ancient Oceanic Crust & India Plate died resulting in the birth of the new plate boundary between Eurasian Plate & the Indian Plate. :hihi:

[kingwinner]

In the notes, it says,

"Collision

-subduction of oceanic plates between two continents, e.g. between India and Asia..."

 

It says "continental collision" on the top and now it says "subduction of oceanic plates"? :rolleyes: weird...

But, what does it mean by subduction of oceanic plates between two continents? (Is this referring to ancient times where the plate boundary between Indian plate and Eurasian plate is in the middle of the ocean?)

 

If so, I have another question, for example, plate A and plate B is a oceanic-oceanic convergence:

-at first, A subducts under B

-ocean crust of A is completely subducted and continental crust in A meets oceanic crust of B

-after this, what could happen to make continetal crust of A to meet continental crust of B? (B subducting under A, instead?)

[Turtle]

In the notes, it says,

"Collision

-subduction of oceanic plates between two continents, e.g. between India and Asia..."

 

It says "continental collision" on the top and now it says "subduction of oceanic plates"? :rolleyes: weird...

But, what does it mean by subduction of oceanic plates between two continents? (Is this referring to ancient times where the plate boundary between Indian plate and Eurasian plate is in the middle of the ocean?)

____The between here does not refer to a physical position, but rather an association, e.g. "...tonights game between the Mariners & Red Sox." :hihi:

[kingwinner]

"-subduction of oceanic plates between two continents, e.g. between India and Asia"

 

then how come there are oceanic plates there? The colliding edges of the Indian plate and Eurasian Plate are both continental, ie there is no ocean between them...

[Turtle]

"-subduction of oceanic plates between two continents, e.g. between India and Asia"

 

then how come there are oceanic plates there? The colliding edges of the Indian plate and Eurasian Plate are both continental, ie there is no ocean between them...

 

___There is no longer an ocean between them, but there once was; the India plate closed the gap & crashed into the Asian plate. :)

[kingwinner]

"Collision

-subduction of oceanic plates between two continents, e.g. between India and Asia

-formation of the Himalayan mountains, crust also becomes thincker"

 

Furthermore, it is the collision between the 2 continental plates of India and Eurasia which uplifted the plates at the covergence boundary, forming the Himalaya mountains, instead of the collision of 2 oceanic plates...this note is really confusing...

[Turtle]

"Collision

-subduction of oceanic plates between two continents, e.g. between India and Asia

-formation of the Himalayan mountains, crust also becomes thincker"

 

Furthermore, it is the collision between the 2 continental plates of India and Eurasia which uplifted the plates at the covergence boundary, forming the Himalaya mountains, instead of the collision of 2 oceanic plates...this note is really confusing...

___I agree it is confusing; do they also give an example of oceanic plates colliding? My understanding was that the India Plate/Asia Plate boundary constituted a "locked" or "butted" interface. Ah well...science is always amendable. If your instructor is open to students dropping into the office for counsel, perhaps you can find clarification there?

____Geology is such a broad subject with so many new discoveries everyday that it is no surprise to find inconsistencies in sources; it is to your credit that you have sought enough sources to bring the inconsistencies to light. If you find clarification, please post it up. :)