Lecture 3: Plate Tectonics

Question 1

1858: Snider – existence of a great region of *
1890: Edward Suess – *
1915: Alfred Wegener – * {Challenge: not able to provide the mechanism on how continents drifted apart}

Answer 1

dry land before the Great Flood
breakup of supercontinent; Gondwanaland
Continental drift

Question 2

• – existence of a great region of dry land before the Great Flood
• – breakup of supercontinent; Gondwanaland
• – Continental drift

Answer 2

1858: Snider
1890: Edward Suess
1915: Alfred Wegener

Question 3

Challenge for continental drift

Answer 3

{Challenge: not able to provide the mechanism on how continents drifted apart}

Question 4

All lands

Answer 4

Pangaea

Question 5

All water

Answer 5

Panthalassa

Question 6

Pangaea Breakup:
Laurasia {}
Gondwanaland {}

Answer 6

(North America, Europe, Asia)

South America, Africa, India, Australia, Antarctica

Question 7

Evidence for Continental drift

Answer 7

1. Global geography
2. Rock sequences
3. Fossil
4. Paleoclimate

Question 8

Clue from global geography

Answer 8

Continental fit

Coastlines of Africa + South America

Question 9

{Challenge: coastlines are constantly modified by erosion and deposition}
What did Edward Buller use?

Answer 9

– used continental shelf

Question 10

Clues from Rock Sequences

Answer 10

Mountain Ranges
Appalachian Mountains (N America), 
British Isles, Caledonian Mountains (Scandinavia)

Question 11

remains, trace, imprints of organisms that have been preserved in the Earth’s crust for 10,000 years +

Answer 11

Fossils

Question 12

Fossil Distribution

Answer 12

1. Mesosaurus – aquatic reptile; eastern South America and South Western Africa
2. Lystrosaurus – strictly land-dwelling reptile; (Africa, Antarctica, Inda)
3. Glossopteris “fossil seed fern” – too large to be carried by wind (Africa, Australia, India, South America)

Question 13

aquatic reptile; eastern South America and South Western Africa

Answer 13

Mesosaurus

Question 14

strictly land-dwelling reptile; (Africa, Antarctica, Inda)

Answer 14

Lystrosaurus

Question 15

too large to be carried by wind (Africa, Australia, India, South America)

Answer 15

Glossopteris “fossil seed fern”

Question 16

Glacial deposits – SA. Africa, India, Australia {tropical countries = rocks related to glaciers}; Coal fields in the northern hemisphere
Southern continents are joined together and located near the South Pole (Antarctica, Arctic}

Answer 16

Paleoclimate

Question 17

Glacial deposits in

Answer 17

SA. Africa, India, Australia

Question 18

Proponent of seafloor spreading

Answer 18

Harry Hess

Question 19

Place of continuous generation of oceanic crust;

Answer 19

Mid-oceanic ridge:

ridge crest

Question 20

7 major plates

Answer 20

African Plate
Indo-Australian Plate
Antarctic Plate
Eurasian Plate
North American Plate
Pacific Plate
South American Plate

Question 21

MINOR PLATES

Answer 21

Somali Plate · Nazca Plate
Philippine Sea Plate · Arabian Plate
Caribbean Plate
· Cocos Plate
Caroline Plate · Scotia Plate
Burma Plate · New Hebrides Plate

Question 22

Elaborate Plate Tectonics:

Answer 22

Continental drift + seafloor spreading

*Earth is composed of lithospheric plates

Question 23

Further Evidence of Plate Tectonics

Answer 23

1. Hotspots
2. Paleomagnetism
3. Seismic Activity

Question 24

area of high temperature

*Examples: Hawaii, Emperor Seamount chain

Answer 24

Hot spots

Question 25

Hawaii, Emperor Seamount chain | * interacts with *

Answer 25

*Pacific Plate interacts with Eurasia

Question 26

form magnetic stripes depending on Earth’s polarity. Record magnetic mineral; generate oceanic lithosphere.

Answer 26

Paleomagnetism

Question 27

– temperature at which a mineral’s magnetism is lost

Answer 27

Curie point

Question 28

Curie point of Magnetite

Answer 28

585 C

Question 29

* deep earthquakes --> trenches | * shallow earthquakes --> boundaries of plate

Answer 29

Seismic Activity

Question 30

Divergent plate boundary | centers, margin, where?

Answer 30

{Spreading centers} *Constructive margin Mid-oceanic ridge

Question 31

Process involving divergent plate boundary

Answer 31

*Magma upwelling --> Rifting Event --> produce body of water

Question 32

Convergent plate boundary | margin, where?

Answer 32

Destructive margin * subduction zones – trenches * orogenic belts – mountain

Question 33

O-C Convergence Float: Sink: Product:

Answer 33

Float: C Sink: O Product: Continental volcanic arc, trench

Question 34

O-O Convergence Sink: Product:

Answer 34

Sink: Denser, older, faster Product: Island Arcs

Question 35

C-C Convergence | Product:

Answer 35

Product: Mountains

Question 36

Collision of * to * forming the Himalayas | What type of convergent boundary?

Answer 36

India, Eurasia | C-C

Question 37

Transform | Define, Margin, Example

Answer 37

Two plates slide past each other Conservative margin San Andreas Fault; East Pacific Rise

Question 38

Driving mechanism of Plate Tectonics

Answer 38

Plate-Mantle Convection, | Slab pull and ridge push

Question 39

* is the underlying driving force for plate movement | * models

Answer 39

Convective flow (Plate-Mantle Convection) TWO LAYER MANTLE CONVECTION MODEL WHOLE MANTLE CONVECTION MODEL

Question 40

Results from the sinking of a cold, dense slab of lithosphere

Answer 40

Slab pull

Question 41

Gravity driven force that results from the elevated position of the ridge where

Answer 41

Ridge push | oceanic ridge

Question 42

Philippine Tectonics | seismically active island arc origin

Answer 42

1. Philippine Mobile Belt

Question 43

aseismic continental origin

Answer 43

2. Palawan Microcontinental Block

Question 44

Oceanic-Oceanic Convergence | West and East

Answer 44

``` {West} 1. Manila Trench 2. Negros Trench 3. Sulu Trench 4. Cotobato Trench {East} 1. East Luzon Trough 2. Philippine Trench ```

Question 45

Marginal Basins

Answer 45

1. West Philippine Sea 2. Sulu Sea 3. Celebes Sea 4. Philippine Sea

Question 46

Oceanic Bathymetric Highs (emerged, elevated sea floor)

Answer 46

1. Scarborough Seamounts | 2. Philippine Rise

Question 47

Another distinct feature of Philippine Tectonics

Answer 47

Philippine Fault Zone

Question 48

The concept of a floating lithosphere in gravitational equilibrium with the Earth’s asthenosphere such that the tectonic plates "float" at an elevation which depends on their thickness and density.

Answer 48

Isostasy

Question 49

Isostasy is the concept of a * in gravitational * with the Earth’s * such that the tectonic plates "*" at an elevation which depends on their thickness and density.

Answer 49

floating lithosphere, equilibrium, asthenosphere | float

Question 50

Isostasy is the concept of a floating lithosphere in gravitational equilibrium with the Earth’s asthenosphere such that the tectonic plates "float" at an elevation which depends on their *

Answer 50

thickness and density.

Question 51

Mountains have “roots” which extend down into the mantle. Thus, elevation is proportional to the depth of the underlying “root”.

Answer 51

Airy-Heiskanen Model

Question 52

Elevation is inversely proportional to density. Thus, the higher the mountain, the lower is its density; that is, light rocks “float” higher.

Answer 52

Pratt-Hayford Model

Question 53

the lithosphere acts as an elastic plate and its inherent rigidity distributes local topographic loads over a broad region by bending.

Answer 53

Vening Meinesz/Flexural Model

Question 54

Height is proportional to depth

Answer 54

Airy-Heiskanen

Question 55

Elevation is inversely proportional to density

Answer 55

Pratt-Hayford

Question 56

Weight of the load bends or flexes the lithosphere/asthenosphere

Answer 56

Vening Meinesz/Felxural Model

Question 57

concept that explains a floating crust in a gravitational balance

Answer 57

Isostasy