My Notes: Volcanism, Plate Tectonics, and Igneous and Sedimentary Rocks Flashcards
Are all hotspots active right now?
no they come and go
Hawaii, Iceland, and Yellowstone are all what types of volcanoes?
Hot Spot volcanoes
What are the two types of hot spot volcanoes?
1) extra large plumes along divergent plate boundaries (Iceland)
2) Within plate volcanoes
- small plumes rise under a plate
- Intra-plate hot spots
What are intra-plate hot spots?
Occur inside individual plate (Hawaii and Yellowstone)
Do hot spots interfere with plate movement?
No, hotspots don’t interfere with individual plate movement
True or False: hot spots can occur in continental or oceanic lithosphere.
true
Are magma chambers that exists at depths relatively simple or are they complex?
complex
When do guyots form?
When volcano is at position that it is almost submerged, wave rods it and we get sea mounts called guyot.
Hawaii:
Midway volcanic rocks - ___Ma
Upwards- ___Ma
Downwards - ___Ma
- 40
- 65
- 5-0
What is magma contamination?
Rocks (all Precambrian) melt around magma and change its chemistry
What do precambrian rocks melt at?
7000 degrees C
What are the two types of volcanism that occurs in Northwestern U.S.?
- fissure eruptions (craters coming up under a continent–lava seems to be coming up and puddling at lower part of crust)
- subduction-related volcanoes
What happens when lava puddles under the crust, including melting temperatures?
When it puddles, lava is 1000-12000 degrees C. Rocks (all Precambrian) melt at 700 degrees C so they melt around magma and change its chemistry to felsic.
Aside rain___in gases.
SO2
How does volcanism cause aside rain?
As their gas particles get tied in the atmosphere.
Tsunamis: ___km near short
___km/hr
- 50-200
- 800
Where do most tsunamis occur?
in Pacific
What are the two types of intrusive rock bodies (broad)?
1) Hypabyssal
2) Plutonic
What are hypabyssal intrusive rock bodies?
- subvolcanoes (dikes, sills, laccoliths)
- small bodies
- shallow injection
- injected at depths less than 5-10 km
What are plutonic intrusive rock bodies?
- several km depth –> considerable depth
- large bodies
- many throw off dikes and may have fed volcanoes
- several km wide
What are the three types of relative orogenic age for intrusive bodies?
- Pre-orgenic rock
- syn-orogenic rock
- post-orogenic rock
What is the relative age of batholiths?
Batholiths are almost all stn-orogenic – every young and old orogenic belt has them.
What is the composition of batholiths?
Almost completely felsic
What are talus/scree?
Rock bodies that have fallen - slide from gravity, running water and rain .
What does every bed in rock strata represent?
- a geological deposition event
- if conditions remain the same, beds will mostly look the same.
- size of grains deposited change as conditions change
- events can last for seconds-centuries
What do rocks represent?
Rocks represent events
