Lecture 5- Marine Geology 2

Question 1

Pangaea

Answer 1

the supercontinent that split apart to form the present-day configuration

Question 2

Wilson Rock Cycle

Answer 2

• process in which continents have repeatedly collided and broken apart
• happened even before Pangaea

Question 3

divergent boundaries occur between

Answer 3

• ocean and ocean

- continent and continent

Question 4

convergent boundaries occur between

Answer 4

• ocean and ocean
• ocean and continent
• continent and continent

Question 5

3 plate boundaries

Answer 5

• transform
• divergent
• convergent

Question 6

earth’s 2 types of crust

Answer 6

• oceanic

- continental

Question 7

oceanic crust

Answer 7

• thin (5 km)
• more density so floats deeper in the mantle
• consists mostly of basalt

Question 8

continental crust

Answer 8

• thick (70 km)
• less dense so they float higher in the mantle
• consists mostly of granite

Question 9

divergent boundaries

Answer 9

• occur where plates are moving apart

- most of these boundaries are mid-ocean ridges and less commonly, continental rifts

Question 10

examples of new divergent boundary

Answer 10

East Africa rift zone

Question 11

example of mature divergent boundary

Answer 11

mid-ocean ridges

Question 12

hydrothermal vent systems

Answer 12

found at mid-ocean ridge spreading centers

Question 13

continental boundary: ocean and continental

Answer 13

• ocean is more dense so it subducts and is pushed back down into the mantle
• generates deep ocean trenches and explosive volcanoes

Question 14

examples of ocean crust colliding with continents

Answer 14

• North Cascade Mountains
• Andes Mountains
• Mt. Saint Helens (volcano)

Question 15

continental boundary: oceanic and oceanic

Answer 15

• the plate that gets subducted is the one furthest from its spreading center
• deep oceanic trench (sometimes filled with sediment)
• older, colder, and more dense subducts

Question 16

Island Arc

Answer 16

• chain of volcanoes

- ex. Aleutian Islands

Question 17

continental boundary: continent and continent

Answer 17

• neither wants to subduct

- results in mountains (ex. Mt. Everest)

Question 18

transform plate boundary

Answer 18

• plates slide laterally relative to one another

- example: San Andreas Fault

Question 19

type of marine sediment

Answer 19

• terrigenous
• red clay
• calcareous ooze
• siliceous ooze

Question 20

sediment rate of red clay

Answer 20

less than or equal to 1 cm per 1000 year

Question 21

sediment rate of ooze

Answer 21

1-5 cm per 1000 year

Question 22

terrigenous sediment

Answer 22

causes sediment thickness to be high near coast

Question 23

red clay

Answer 23

• found in open ocean

- created by slow rain of continental dust and very low biological addition

Question 24

calcareous/ siliceous ooze

Answer 24

• found in high biological productivity

- absence of terrigenous sediment and dilute red clay

Question 25

accumulation of sediment

Answer 25

• very slow

- a 10 m sediment core can represent a record of a million years of earth history

Question 26

proxy measurement of past ocean conditions

Answer 26

remains of planktonic organisms contained within the sediment cores reveal information about growth conditions of the ocean

Question 27

calcite in shells

Answer 27

calcite in shells grown in colder temperatures have more 18O than calcite grown in warmer temperatures

Question 28

6th mass extinction

Answer 28

caused by humans