Chapter 10: History of Continents

Question 1

How old are the following:
Oceanic crust
Continents

Answer 1

Oceanic crust: <200 Mya
Continents: up to 4 Gya

Question 2

Define shield and platform.

Answer 2

Sheld: exposed crystalline proterozoic basement.

Platform: proterozoic basement covered by < few km flat sediment.

Called shield because it looks like battle shield was stuck into ground.

Question 3

What do basins and domes each do?

Answer 3

Basins: form reservoirs.

Domes: trap oil and gas

Question 4

What geological features are in the North American cordillera?

Answer 4

Uplift and orogeny

Regujenation

Crustal Stretching

Question 5

Orogeny

Answer 5

The process of mountain building

Question 6

Farallon Plate

Question 7

Age categories of tectonic provinces

Answer 7

Hadean (fiery)

Archeon (ancient)

Proerozoic (before/early life)

Phanerozoic (with life)

• Paleo (old) era
• Meso (middle) era
• Ceno-zoic (modern) era

Question 8

Cratonic Keels

Answer 8

The strong, cool payer of lithospheric mantle material beneath a continental craton extends to a depth of more than 200 km. They are buyant.

S-wave velocity structure

100-175 km depth

Question 9

Kimberlite Mines

Answer 9

Where diamonds form at very high pressure (>150 km depth)

Must rise quickly or will convert to graphite

Question 10

Accreted Terrains

Answer 10

Addition to the edges of cratons through tectonics

Question 11

Continental crust formation

Answer 11

Collision of volcanic arcs and oceanic plateau to form larger crustal fragment

Question 12

Accretion and types

Answer 12

A process by which material is added to a tectonic plate or a landmass. This material may be sediment, volcanic arcs, seamounts or other igneous features.

Types:

• accretion of a buoyant fragment to a continent
• accretion of an island arc to a continent
• accretion along a transform fault
• accretion by continental collision and rifting

Question 13

Wrangellia

Answer 13

A land mass transported to the NW coast of North America from 5000 km away. Much of western North America is made up of exotic terrains accreted over the past 200 million years.

Question 14

The WIlson Cycle

Answer 14

The tectonic processes that continue to break apart and rebuild continents through opening and closing of dynamic seas.

Question 15

Epeirogeny

Answer 15

Non-tectonic vertical deformation of continents

Cooling and heating of lithosphere

Weight of accumulating sediments or glacial ice

Question 16

Glacial rebound

Answer 16

The weight of a continental glacier downwarps the continental lithosphere, which rebounds once the ice is removed.

Question 17

Heating of lithosphere

Answer 17

Upwelling of mantle material causes uplift and thinning of the continental lithosphere.