Page 129 - Fundamentals of Geomorphology

112 STRUCTURE

b
a
() Continental collision ( ) Island arc–continent collision
Passive Continental-
continental margin margin orogen
Ocean

i. Precondition i. Precondition
Intercontinental- Modified continental-
collision orogen margin orogen

ii. Collision ii. Collision
Subduction halted
(island arc subduction?)

d
c
() Continent–island arc collision ( ) Island arc collision

i. Precondition i. Precondition
Modified passive Compound intra-
continental margin oceanic island arc

ii. Collision ii. Collision
Subduction halted
Oceanic Continental Volcanic (island arc subduction?)
crust crust rocks

Figure 4.11 Four kinds of collisional margins. (a) Intercontinental collision orogen formed where two continental plates
collide. An example is the Himalaya. (b) Modified continental-margin orogen formed where an intra-oceanic island arc
moves into a subduction zone bounded by continental crust. (c) Modified passive continental margin formed where a
continent moves towards a subduction zone associated with an intra-oceanic island arc. (d) Compound intra-oceanic
island arc formed by the collision of two intra-oceanic island arcs.
Source: Adapted from Summerfield (1991, 59–60)