Lecture 6 - Flow Of The Continents

Question 0

Harold William Welllan (1909-1999) as a young geologist what did he search New Zealand for?

Answer 0

Natural resources like Muscovite Mica

Also found in paints, plastics, electronics and cosmetics

Question 1

When will the next Pangea occur?

Answer 1

+250Ma

Question 2

What did Wellman do when he travelled NZ?

Answer 2

Mapped major geological structures

Question 3

Wellman produced a detailed map showing what?

Answer 3

The relationships between faults and earthquakes in the region of New Zealand

Question 4

What did Wellman think of the topography of Milford Sound, in fiord land of the South Island?

Answer 4

It was the result if major uplift linked to tectonic activity

Question 5

The marine terraces on the Wairarapa coast, North Island, New Zealand, show what?

Answer 5

The uplift that takes place in response to multiple earthquake cycles

Each raised platform records a large earthquake

Question 6

Why is there so much seismic activity and uplift across a 250km wide zone in NZ?

Answer 6

NZ lies on the boundary of two tectonic plates, the Australian and Pacific

Question 7

The USA built listening stations to do what?

Answer 7

Detect nuclear explosions

Question 8

What is the Comprehensive Nuclear Test Ban Treaty Organisation?

Answer 8

Shows location of nuclear explosions over a timeline

Question 9

The WSSN (Worldwide Standardised Seismic Network) was able to detect what?

Answer 9

Earthquakes associated with fault movements

Question 10

Narrow linear fault zones suggest what?

Answer 10

Spreading ridges

Question 11

Where do more profuse earthquake zones occur?

Answer 11

Around mountain areas

Question 12

What did Dan Mckenzie and Phillip England ask?

Answer 12

How do continents behave when they collide? And do mountains like the Himalayas behave like fluids or rigid plates?

Question 13

As you travel north what happens to the topography and geology?

Answer 13

It changes

Question 14

What is the Tibetan Plateau?

Answer 14

A flat area nearly 2000km wide, average elevation 5km

Question 15

How did Phillip England attempt to model the Tibetan Plateau?

Answer 15

Using Newtons laws of motion, concepts of fluid behaviour and plate tectonic theory

Question 16

What had a 6000km journey before it collided with Asia 40-20million years ago?

Answer 16

The India continent

Question 17

What is the sacred amount Kaliash, 6638m high built from?

Answer 17

Ancient marine sediments once deposited at the bottom of Tethys Ocean which separated India and Asia

Question 18

What resources can be found where India and Asia collided?

Answer 18

Petroleum

Mineral and metal

Question 19

Subduction of Tethys ocean allowed what?

Answer 19

The Indian continent to move northwards at 5cm yr and push into Eurasia

Question 20

How thick was the lithosphere and Indian plate, also continental crust?

Answer 20

100km

Question 21

How thick was the Eurasain plate?

Answer 21

35km

Question 22

When mountains flow up what type of root is formed?

Answer 22

And iceberg like roof

Question 23

Explain 2 things which causes the Tibetan Plateau?

Answer 23

1. Material flows upwards then reaches a max height

2. Rather than going higher, Himalayas becomes wider, forming Tibetan Plateau

Question 24

Fluid mechanics explain a lot about Tibet, but what does it not explain?

Answer 24

Why it is so high

Question 25

When continents collide and one ate is pushed below, what happens to this plate over time?

Answer 25

More of the lower plate is pushed into the mantle. It is cold and dense. The asthenosphere is hot, less dense and rises so the plate detaches the cold lithosphere.

Question 26

Detachment of the lithosphere can cause volcanic activity why?

Answer 26

A great weight is lost, so it causes a sudden uplift and fracturing of Tibet, allowing magma to rise and escape.

But as it’s raised to high without support, the mountains collapse and flow away

Question 27

What happened on October 8 2005?

Answer 27

7.6M Kashmir Earthquake

Question 28

How many were killed, injured and homeless from the October 8 Kashmir Earthquake?

Answer 28

• 86k dead
• 69k injured
• 4milli homeless

Question 29

Conclusion: when continents collide they do not subduct but…?

Answer 29

Push to form oreogenic belts or mountains

Question 30

Conclusion: collision of continents thickens the continental crust, how?

Answer 30

It pushes up as well as down into the athenosphere

Question 31

Conclusion: as rock is squeezed it will undergo solid state flow, what can this cause?

Answer 31

Part of the lithosphere to detach

Question 32

Conclusion: what is the result from continents colliding in the Himalayas?

Answer 32

Rapid uplift and formation of the Tibetan Plateau