topic 4 plate tectonics

Question 1

Landforms are the result of what major groups of processes?

Answer 1

Land building: volcanic and tectonic forces (initial landforms ‘primary’) and Land denudation: weathering and erosion (sequential landforms ‘secondary’)

Landforms reflect a balance between internal earth forces and bring fresh rock to the surface and denudation processes that remove and transport mineral matter

Question 2

what transports the most rock and soil annually?

Answer 2

1. rivers 53 billion tons 2. humans 45 billion tons 3. oceanic volcanoes 30 billion tons 4. mountain building 14 billion tons 5. glaciers 4.3 (10) billion tons

Question 3

earth structure

Answer 3

Core, mantle, and crust/lithoshere

increasing temperature and density of material with depth

Question 4

Continental drift

Answer 4

the idea that all landmasses were once all one large continent, pangea, surrounded by a single ocean.

Pangea broke apart over hundreds of millions of years ago because of development of rift zones within continents

continents spread apart and ocean basins developed by process of sea-floor spreading

Question 5

plate tectonics

Answer 5

The theory describing the origin, movement, and recycling of lithosheric plates and the resulting landforms

origin was the theory of seafloor spreading; new lithosphere forms at mid-ocean ridges, and old lithosphere is recycled deep into the mantle through subduction

Question 6

what is subduction?

Answer 6

the process in which oceanic lithosphere from one plate bends and dives into the mantle beneath another plate

subduction only occurs where Oceanic lithosphere subducts beneath continental lithosphere/oceanic lithosphere

Question 7

concept of a lithospheric ‘plate’

Answer 7

Rigid lithospheric rocks are “floating” on the denser, plastic asthenosphere

The lithosphere is broken into large plates (AKA ‘tectonic’ plates)

plates are flexible yet brittle (fractures are known as “faults”)

Question 8

Two types of plates

Answer 8

14 total plates (7 primary plates, 7 secondary plates)

Primary plates: the African plate, Antarctic plate, Eurasian plate, Indo-Australian plate, North American plate, Pacific plate, and the South American plate

secondary plates: the other 7

Question 9

How to find plate boudaries?

Answer 9

Earthquake activity reveals plate boundary locations
Earthquakes occur in geographic patterns that delineates the outlines of lithospheric plates

Question 10

How do plates move?

Answer 10

Ridge push: rising magma along a mid-ocean ridge lifts oceanic lithosphere and forms slopes

mantle drag: movement of plates caused by friction between moving asthenosphere and the lithosphere

Slab pull: the weight of the subducting portion of a plate accelerates plate movement by pulling the plate deeper into the mantle

Question 11

absolute velocity

Answer 11

how fast the plate is moves in relation to a fixed point

Question 12

Relative velocity

Answer 12

How fast a plate moves in relation to the speed of an adjacent moving plate

Question 13

What is uplift?

Answer 13

change in land/rock surface vertical position relative to a fixed datum (e.g. sea level)

Question 14

Total uplift

Answer 14

the sum of Tectonic uplift (due to collisions and tectonic movements) and isostatic uplift (due to the difference in density between mantle and the crust)

when erosion occurs, there is an isostatic adjustment (due to the difference in density between crust and mantle). for each meter of erosion, isostatic response lifts the underlying rock up by ~82cm

Question 15

Plate boundaries

Answer 15

Divergent: where two plates move apart
Convergent: where two plates move towards each other
transform: where one plate slips laterally past another

Question 16

Divergent boundary Landforms

Answer 16

mid-ocean ridges (~underwater mountains): rising magma pushes up, which pushes the slab outward

Rifting: region where continental crust is stretching and splitting.

Rift valley is a long valley with volcanoes formed by rifting of continental crust. may flood with seawater, creating an inland sea and, with more time, a new ocean basin

Question 17

types of convergent plate boundaries

Answer 17

Continental-Continental; Oceanic-Oceanic; and Oceanic-Continental

Question 18

What forms along convergent plate boundaries where subduction occurs?

Answer 18

Explosive Volcanoes form along convergent plate boundaries

Question 19

Can continental lithosphere subduct?

Answer 19

Continental lithosphere cannot subduct because it is less dense than oceanic lithosphere

Question 20

How is oceanic crust recycled?

Answer 20

as the oceanic lithosphere is subducted, it is consumed and recycled as mantle convection occurs, the rich minerals of the mantle surfaces as crust-making lava at mid-ocean ridges and volcanoes

Question 21

Flux melting

Answer 21

the process in which the mantle mixes with seawater and melts into magma (occurs only in subduction zones)

Question 22

Volcanic arc

Answer 22

a long chain of volcanoes on the margin of a continent where subduction is occurring

magma rises up, melting its way through margin of continental crust, producing a volcanic arc

Question 23

Where does continental arcs form?

Answer 23

Continental arcs are a long chain of volcanoes that form only on the margins of a continent where an oceanic plate subducts beneath continental plate

Question 24

How do island arcs form?

Answer 24

Island arcs are a chain of volcanic islands formed when oceanic lithosphere subducts beneath oceanic lithosphere of another plate

Question 25

Collision

Answer 25

the process in which continental crust of two plates converges

Results in formation of a mountain belt as crust is heaved upwards

non-volcanic mountains form where the crust is thickened and buckled by collision

Question 26

explain continental-continental convergent plate boundary (with ocean basin)

Answer 26

two plates are converging, the oceanic lithosphere subducts beneath the continental lithosphere, a volcanic continental arc is formed as magma rises up near the site of subduction. once the ocean lithosphere is fully subducted, the continental crust is pushed and fuses together into a single new plate. the oceanic lithosphere detaches and sinks deep into the mantle

Question 27

accreted terrane

Answer 27

a mass of crust that is transported by plate movement and fused onto the margin of a continent

Question 28

What happens at Transform plate Boundaries

Answer 28

At transform plate boundaries, crust is being sheared and torn, but no new crust is formed, and no old crust is recycled into the mantle

Question 29

Tectonic landforms

Answer 29

compression results in folding and faulting
Extension results in thinning and faulting
Shear results in bending and faulting

Question 30

Hot spot

Answer 30

a volcanically active region that is caused by a mantle plume

Question 31

Mantle Plume

Answer 31

A vertical column of hot rock that extends down as far as Earth’s outer core (e.g. Yellowstone)

Question 32

Fold

Answer 32

A wrinkle in the crust that results from deformation caused by geologic stress

Question 33

Two major types of folds

Answer 33

anticlines: fold in the crust with an archlike ridge

Synclines: fold in the crust with a U-shape dip

Question 34

Fault

Answer 34

A fracture or a break in the crsut where movement and earthquakes occur

Normal fault (tension)
Reverse fault (compression)
Strike-slip fault (shear)