collisional orogens

orogenic wedge

wedge shaped body of deformed rock formed by stacking of thrust sheets during collision

how does an orogenic wedge grow

through progressive stacking of thrust sheets under compression

foreland basin

basin formed by bending (flexure) of lithosphere under weight of mtn belt

why do foreland basins form

due to subsidence caused by load of growing orogen

what fills foreland basins

thick sediments eroded from adjacent mtns

ex of foreland basin

Himalayan Ganges Basin

Alpine foreland basin

Molasse basin

nappe

large sheet of rock transported long distances along low-angle thrust faults

what do nappes indicate about deformation

sig horizontal shortening & strong compressional forces

where are nappes well developed in Alps

systems such as Helvetic, Penninic & Austroalpine nappes

Iapetus ocean

ancient ocean closed in formation of the Caledonides

where are Caledonian nappes found today

N regions like Scotland & Norway

how do nappes relate to orogenic wedges

nappes are building blocks that stack to form wedge

how are foreland basins linked to orogenic wedges

growing wedge adds weight causing lithospheric bending & basin formation