Magma Composition
What is dissolved in magma?
Gas - H2O, CO2, NO2, SO2
How many magma types have been taught
3 types - Basaltic, Andesitic, Rhyolitic
What volcano is the most common on Earth
Composite/Stratovolcano
Which lava is created on the ocean floor when magma rises in spreading zones?
Pillow
What is the most abundant gas in volcanic eruptions/magma?
Water Vapor
What is SiO2?
Silica - silicon and oxygen - two most abundant elements in the earth's crust.
Which type is the most viscous and holds the most gas - the most violent
Rhyolitic
The Pacific Ring of Fire is made up of mostly this type of volcano?
Composite/Strato
Which lava is common in Hawaii and is fast moving, low viscosity and low in silica and trapped gases
Pahoehoe
What is molten rock (liquid rock) made of?
Melting minerals and elements
What effect does silica have on magma characteristics?
Controls the viscosity of the magma - amount of flow
Basaltic magma is common where?
shield volcanoes, ocean floor spreading zones and divergence.
What type of volcano is the big island of Hawaii?
Shield - intra-plate volcanism - hotspot
Which lava cools to form large cubic shaped - due to the high viscosity and silica content
Block
What does magma crystallize and consolidate to become?
Intrusive igneous rock
What characteristic will control the amount of dissolved gases are trapped in the magma?
Viscosity which is controlled by the amount of silica 45%-80%
Is Andesitic magma slow moving, medium speed or fast moving?
Medium
Andesitic and Rhyolitic magma creates what kind of volcanoes?
Composite/strato
Which Hawaiian named lava hardens to create jagged and sharp surface
A'a
Change in pressure, decompression melting, mixing.
Explain the relationship between silica, temperature, viscosity and dissolved gases in magma
More silica = lower temp = higher viscosity = more dissolved gas is trapped
What percent of silica does Rhyolitic magma have?
65-78% (high) = viscous
Which volcano is steep sided, in groups and is small?
Cinder or Scoria (made from ash)
What compound can create a slower moving lava?
SiO2 - silica (viscosity)