Magma Flashcards
Decompression melt
Decrease pressure
Hot rock rise toward surface
Temp constant; pressure decrease
Divergent and hot spots
Volatiles
H20, CO2
Addition of volatiles
Are heated and released into rock,
addition of water lower melting temp of rock by breaking chemical bonds
Temp and pressure are constant
Subduction zones
Addition of heat
Pressure constant; temp increase
Melting of lithosphere as magma rises through surface
Changes composition of magma
What differs volcanos
Magma chemistry
Temp of magma
Volition content
Size of length of eruption
Viscosity
How magma flows; resistances to fluid
High viscosility=thick like peanut butter
Increases with decreasing temp (maple syrup)
Increases with Silica content (add more flour-thicker)
Increase with increase crystal content
Volatile (gas) content
Amount determines explosity of volcano
Gas rich=explosive
Gas poor=effusive
Fragmentation- quickly when pressure decreases rapidly
Magma properties (classification)
Silica content Magma temp Magma viscosity Volatile content Explosity
Type of magma
Magic
Intermediate
Felsic
Mafic
Silica-50 Temp-1200 C Viscosity-low Volatile-low Explosity-low Less silica content, highest temp, lowest in everything else
Intermediate
Silica-60 Temp-1830 F Viscosity- medium Volatile- medium Explosity-medium Medium in everything
Felsic
Silica-70 Temp-800 C Viscosity-high Volatile-high Explosity-high Lowest temperature but highest in everything else Light color to its rocks