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Mountains, Continents, and SC Geology
Terms in this set (27)
Nature of Continents?
are made and deformed by plate tectonic processes
Continental rocks are generally older than?
What does lithosphere float on?
a viscous layer below the continents
Where is the asthenosphere?
within the Earth's mantle
What are components of continents?
Stable cratons: shields and platforms;
Folded mountain belts (orogens)
Formation of Cratons:
granite-greenstone terrains; high-grade metamorphic terrains
What are continental shields?
Central, oldest rocks in continents (up to 3.96 boy), low elevation and relatively flat, "crystalline basement" metamorphic and igneous rocks, once tectonically active
What are stable platforms?
shields covered with horizontal sedimentary rocks; sedimentary, limestones, and shales deposited in ancient shallow seas
(How Continents Grow) What is magmatic differentiation?
magma transferred from mantle to continents at subduction zones
What is continental accretion?
buoyant fragments of crust attached to continents as the result of plate motions; amalgamation or accretion of terranes, exotic terranes (seem out of place); the volume of the continents has increased by about 2 km3/yr for the past 4 GA
How do continents grow?
accretion of island arcs, accretion of continental fragments, accretion along transform faults, accretion by continental collision/rifting
What is orogeny?
general term for mountain-building processes; folding and thrusting of rock layers; often accompanied by magmatic activity and metamorphism
Where are mountains located?
located at hot spots and plate boundaries
Where are hot spots located?
mid plate- Hawaii
Plate boundary: Iceland
(Mountains) Divergent boundaries:
oceanic spreading centers- world's longest mountain ranges; Continental rifts: E. African Rift, Basin & Range- US
ocean- ocean boundaries: Island arcs- Japan, Philippines, Carolina slate belt;
ocean- continent boundaries: volcanic arc- Andes
Continent- Continent Collision-
Himalayan Mountains and Tibet plateau. Appalachian mountains
What happens during the Wilson Cycle?
repeated opening and closing of ocean basins
(southern appalachians and growth of continents) Continental Accretion:
arc- continent collision
failed rifts, CAMP volcanics
SC Geology: 500-350 my:
Island arcs collided with North America forming Blue Ridge and Piedmont provinces (Carolina slate belt)
Carolina gold belt mineralization within Carolina slate belt
Africa and North america collided forming Pangea and the Appalachian mountain chain. Valley and Ridge fold belt.
What mountain chain runs along the eastern margin of North America?
The Carolina Piedmont is made of?
Island arc rocks accreted to North America
The dip of a layer in a geologic formation can vary between ___________?
Continents are made up of?
Ancient granitic cratons, island arcs accreted to the edges of the cratons, exotic terranes (microplates)