Geologic Materials Flashcards
What are the 3 principle types of material that make up the Earth’s crust?
- Rock
- Sediment
- Magma
Rock
Consolidated mixture of minerals
Sediment
Mixtures of rock, mineral, or organic fragments
Magma
Molten rock
What are the 3 principle types of magmas?
- Mafic
- Intermediate
- Felsic
Mafic Magma
Contains less than 53% silica by weight. Tends to be rich in iron and magnesium oxides, while having little sodium or potassium oxide.
Intermediate/Andesitic Magma
Contains between 54-64% silica by weight.
Felsic/Rhyolitic Magma
Contains more than 65% silica by weight. Tends to have very little iron or magnesium oxide, while having higher amounts of sodium and potassium oxide.
How are magma types divided?
On the basis of composition.
Partial Melting
The creation of magma by melting rock. Rock is not fully melted because it is a consolidated collection of minerals with different melting temperatures.
What determines the melting of rock?
Because of changes in composition, temperature, and/or surrounding pressure.
What determines the kind of magma produced by melting rock?
- The type of rock being melted
2. What happens to the magma and solid residue as melting takes place
Igneous Rock
Formed by the cooling and crystallization of a magma, or the accumulation and consolidation of volcanic ash or other pyroclastic material on or below the Earth’s surface.
What is igneous rock composed of?
Largely silicon/oxygen-rich crystals, glass, or consolidated glass fragments.
How is igneous rock grouped?
By texture and mineral composition.
Extrusive Igneous Rock
Has aphanitic, porphyritic, glassy, pyroclastic, or vesticular textures, and are formed when magma cools or solidifies very quickly on or near the Earth’s surface. They form on or in volcanoes and some shallow underground conduits leading to them.
Examples of Extrusive Igneous Rock
Rhyolite, Andesite, and Basalt
Intrusive Igneous Rock
Have either phareritic or a porphyritic crystalline textures and are formed when magma cools very slowly deep within the Earth’s crust. They form within the crust at depths greater than 4 km.
Examples of Intrusive Igneous Rock
Granite, Diorite, Gabbro, and Peridotite
Felsic Igneous Rock
Rich in felsic materials (potassium, feldspar, sodium rich plagioclase, quartz, and plagioclase), and poor in magnesium silicates (boitite and hornblende).
What color is felsic igneous rock?
Light gray or pinkish
Examples of Felsic Igneous Rock
Rhyolite and Granite
Intermediate Igneous Rock
Have mineral compositions that have nearly equal amounts of felsic minerals (potassium feldspar, quartz, and plagioclase), and magnesium silicates (amphibole, biotite, and pyroxene).
Examples of Intermediate Igneous Rock
Andesite and Diorite
What color is intermediate igneous rock?
Medium gray
Mafic Igneous Rock
Composed largely of iron-magnesium silicates (olivine, pyroxene, and amphibole) and calcium-rich plagioclase.
What color is mafic igneous rock?
Darker shades of gray and black
Examples of Mafic Igneous Rock
Basalt and Gabbro
Ultramafic Igneous Rock
Composed largely of iron-magnesium silicates (olivine, pyroxene, and amphibole), with soe types containing calcium-rich plagioclase.
What color is ultramafic igneous rock?
Black or dark green.
Examples of Ultramafic Igneous Rock
Peridotite
Magmatic Cooling
The cooling and solidification of magma to form igneous rock.
What determines the kind of igneous rock produced by magmatic cooling?
The composition of the magma and how it cools.
