Convergent Mountains Flashcards
What are the main mountain types formed at convergent boundaries?
Volcanic, fold, fault-block, and broadly upwarped mountains.
What is orogenesis?
The process of mountain building through folding, thrust faulting, metamorphism, and igneous activity at convergent plate boundaries.
How do passive margins contribute to fold mountain formation?
Thick sedimentary sequences on passive margins are compressed during convergence, forming fold mountains.
What is a suture zone?
: A boundary where colliding continental plates meet and merge, marking intense deformation and terrane accretion.
How do subduction zones produce volcanic arcs?
The subducting slab melts the overlying mantle wedge, generating magma that forms island or continental volcanic arcs.
What are accretionary wedges?
Accumulations of deformed sediments and fragments scraped from the subducting plate that contribute to mountain belts.
What role do batholiths play in mountain building?
They are large, underground plutonic bodies formed from magma that crystallizes as it rises, later exposed by uplift and erosion (e.g., the Sierra Nevada).
How do fault-block mountains form?
Through crustal extension and tilting along high-angle normal faults, as seen in the Basin and Range province.
What does isostasy mean in mountain building?
The equilibrium where dense mountain roots balance the overlying topography, allowing mountains to “float” on the mantle.
What are terranes?
Small crustal fragments with distinct histories that accrete onto continents during convergence, contributing to continental growth.
How does Andean-type mountain building differ from continental collision?
Andean-type involves subduction of oceanic lithosphere beneath a continent, leading to prolonged magmatism; continental collision involves two continental plates colliding (e.g., Himalayas).
What characterizes folded mountains?
They show long, narrow belts with paired sediment layers (coarse landward, fine seaward) formed from the compression of passive margin sediments.
How do vertical movements affect mountain building?
Uplift and subsidence from isostatic adjustment and mantle convection control mountain elevation and erosion.
How is the evolution of continental crust linked to mountain building?
Accretion, collision, and magmatic differentiation during orogenesis add and recycle crustal material, increasing continental volume over time.
What potential future changes might affect mountain building on Earth?
: If continental crust dominates, reduced subduction could alter plate tectonics, possibly leading to a state with fewer convergent margins—similar to Mars.
