Tectonics & folds

Question 1

lithospheric plates move horizontally over the hotter, semi-plastic ___________ in response to gravity and friction

Answer 1

asthenosphere

Question 2

3 types of plate boundary

Answer 2

1. divergent boundary
2. transform boundary
3. convergent boundary

Question 3

divergent boundaries

Answer 3

• plates move away from each other
• constructive boundaries
• mid-ocean ridges

Question 4

stages of development of divergent boundaries

Answer 4

1. rising magma warps and stretches and thins the crust. Basaltic magma erupts at the surface and an incipient rift forms
2. rift develops and the continental crust broken as the lava begins to fill the rift
3. a narrow sea then develops and a new mid-ocean ridge forms. oceanic crust more developed and the continents will be relatively close (e.g. red sea)
4. ocean basin formed. continent now widely separated (e.g. pacific ocean)

Question 5

drivers of divergent boundary formation

Answer 5

ridge push at elevated ridge, slab pull at trench from old cold and dense lithosphere. CONVECTION

Question 6

Transform boundaries (aka conservative boundaries)

Answer 6

plates move past each other, as the crust is neither created nor destroyed.
Large faults.
link boundaries to other types of plate motion.
Areas of intense seismic activity!

Question 7

lithosphere balanced by destruction at what plate boundary?

Answer 7

convergent

Question 8

convergent plate boundary (aka destructive)

Answer 8

SUBDUCTION occurs.

oceanic trenches, volcanism, metamorphism, earthquakes.

Question 9

oceanic - oceanic convergent boundary

Answer 9

subduction zone where two plates of oceanic lithosphere converge. The older, denser plate dives into the mantle. e.g. volcanic islands, oceanic trenches.

Question 10

what is produced at oceanic - oceanic boundary?

Answer 10

basalt and andesite (mafic)

Question 11

oceanic - continental boundary

Answer 11

subduction zone where one plate of oceanic lithosphere dives under one plate of continental lithosphere. e.g. oceanic trenches, mountain range

Question 12

what is produced at oceanic - continental boundary?

Answer 12

andesite (intermediate)

Question 13

continental - continental boundary

Answer 13

subduction zone where two plates of continental lithosphere converge. Neither sinks because they are too thick and low density. Intense deformation and formation of mountains, plateaus, intrusions…

Question 14

how does deformation at plate boundaries manifest in rocks?

Answer 14

folds, joints, faults

Question 15

_____ is the force applied and causes ______. There are 3 types ___,____,____

Answer 15

stress is the force applied and causes strain. There are 3 types compression,tension,shear

Question 16

folds

Answer 16

rock layers that have been bent or crumpled plastically at high temp and pressure. can be mountain sized or mm. response to compression.

Question 17

Anticline vs. Syncline

Answer 17

• In an anticline the strata are folded upwards to form an arch-shape, with the oldest strata at core.
• Syncline have strata folded down to form trough-shape. Youngest strata at core