? Flashcards
What does mafic stand for
Ma (magnesium) + fe (iron)
What does felsic stand for
Fe (iron)+ si (silica)
What is the temperature for mafic rocks
> 1000 C
What is the temperature for felsic rocks
<800 C
What viscosity do mafic rocks have
Low viscosity
What viscosity do felsic rocks have
High viscosity
What are mafic minerals rich in
Fe & Mg
What are felsic minerals rich in
Na, K & Al
What are mafic minerals poor in
Na, K & Al
What are felsic minerals poor in
Fe & Mg
Mafic minerals are what in silica
low, <50%
Felsic minerals are what in silica
High >65%
What is decompression melting
When stuff melts because of less pressure
What is flex melting
When adding water lowers the melting point of the mantle rock
What is heat transfer
Adding heat until the melting point is reached
What is partial melting
The transformation of a solid into a liquid via melting process
What is fractional crystallization
Some of the magma freezes, eliminating some minerals and leaving others
What is assimilation
When magma melts surrounding rocks which contaminates the magma with new minerals
How are igneous rocks classified
According to mineral composition and grain size
How are igneous rocks classified
According to mineral composition and grain size
What does phaneritic mean
Grains are visible
What is aphanitic
The grains aren’t visible
What is porphyritic
A mix of visible and microscopic
What is groundmass
Crystals too small to see
What is phenocryst
Isolated large crystals
What do granite and rhyolite have
A relatively high ratio of potassium feldspar to plagioclase feldspar; the most felsic type of igneourock
What do grandiorite and dacite have
Still felsic, but has more plagioclase compared to potassium feldspar
What do diorite and andesite have
Intermediate composition; Quartz but no potassium feldspar
What do gabbro and basalt have
Mafic composition; No quartz, contains pyroxene; Plagioclase feldspar is darker, calcium-rich variety
What does peridotite
Ultramafic; Mostly pyroxene and olivine, very little plagioclase feldspar
What comes from the melting of mantle with some fractional crystallization (OCEAN-OCEAN SUBDUCTION ZONES)
Gabbro/basalt and minor diorite/andesite
What comes from direct melting and eruption from the mantle (RIFTS AND PLUMES/HOT SPOTS)
Gabbro/basalt
What comes from the melting of the mantle with extensive crustal assimilation and fractional crystallization (OCEAN-CONTINENT)
Diorite/andesite and granodiorite/dacite
What comes from the direct melting of mantle with crustal assimilation (CONTINENTAL RIFTS AND HOT SPOTS)
Gabbro/basalt and granite/rhyolite (no intermediates)
What is pyroclastic
Mostly groundmass with large clasts (fragments) of minerals and rocks-formed from explosive volcanic eruptions
How does glassy form
When magma cools too quickly
What is from the melting of mantle with some fractional crystallization
Ocean-Ocean
What comes from direct melting and eruption from the mantle
Rifts and Plumes/Hot spot
What comes from the melting of the mantle with extensive crustal assimilation and fractional crystallization
Ocean-Continent
What comes from the direct melting of mantle with crustal assimilation
Continental Rifts and hot spots
