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...]

[Turtle]

Originally Posted by kingwinner

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...]

___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.

[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

[kingwinner]

Originally Posted by 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

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...

"The following processes can FORM( ) new plate boundaries:
a. continental rifting
b. continental collisions"

[Turtle]

Originally Posted by kingwinner

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...

___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.

[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"? 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?)