CONVERGENT BOUNDARIES And Mountains Building Orogenesis the processes

CONVERGENT BOUNDARIES And Mountains Building Orogenesis: the processes that produce a mountain belt. It includes: 1. Folding 2. Thrust faulting 3. Metamorphism 4. Igneous activity (Plutons (batholith) and Volcanism)

Appalachian Mountains

Ural Mountains

Several hypotheses have been proposed for the formations of Earth’s mountain belts:

1. at convergent plates 2. at Continental Plates Collisions 3. due to Continental accretion 4. Fault-block mountains

Convergent boundary of two oceanic plates. island arc and a _____. trench Example: _____ Japan Creates an ____

Convergent Plate Boundaries • Older portions of oceanic plates are returned to the mantle in these destructive plate margins • Surface expression of the descending plate is an deep ocean trench • Also called subduction zones • Average angle of subduction = 45 • 1000’s km long, 8 -12 km deep, 50100 km wide.

Earthquake depth indicates subduction zones

Subduction of oceanic lithosphere at an ocean trench

Convergent boundary of an oceanic plate and a continental plate. Forms a _______ volcanic mountain range trench Examples: Cascades Andes Mts and a _______ or ______

A forearc = forarc =arc-trench gap: a depression in the sea floor located between a subduction zone and an associated volcanic arc. It is typically filled with sediments from the adjacent landmass and the island arc in addition to trapped oceanic crustal material.

Continental-Continental Convergence

Convergent boundary of two continental plates. Forms Himalayas a ______ folded mountain range. Examples: ______, Appalachians Alps, _______