Chapter 5 Igneous Rocks Flashcards
(26 cards)
andesitic magma
Type of magma with a medium amount of silica content.
basaltic composition
a compositional group of igneous rocks indication that the rock contains substantial pyroxene and calcium rich plagioclase feldspar
basaltic magma
magma that has low viscosity and low silica and gas content; eruption is non-explosive
Bowen’s Reaction Series
sequential, predictable, dual-branched pattern in which minerals crystallize from cooling magma
continuous series
The branch of Bowen’s Reaction Series that comprise the plagioclase group of minerals in which reaction of early formed crystals with later liquids takes place without abrupt phase changes . (right side)
discontinuous series
olivine, pyroxene, amphibole, biotite (left side)
extrusive igneous rock
rock that forms from the cooling and solidification of lava at Earth’s surface
Felsic
Describes magma or igneous rock that is rich in feldspars and silica and that is generally light in color.
fractional crystallization
process in which different minerals crystallize from magma at different temperatures, removing elements from magma
granitic composition
igneous rocks composed of light colored silicates, also known as felsic
intermediate composition
a composistional group of igneous rocks that is between granitic and basaltic
intermediate magma
Rock with a chemical content between felsic and mafic compositions.
intrusive igneous rock
rock formed from the cooling and solidification of magma beneath Earth’s surface
Kimberlite
rare, ultramafic rock that can contain diamonds and other minerals formed only under very high pressures.
Mafic
describes magma or igneous rock that is rich in magnesium and iron and that is generally dark in color
partial melting
The process by which most igneous rocks melt. Since individual minerals have different melting points, most igneous rocks melt over a temperature range of a few hundred degrees. If the liquid is squeezed out after some melting has occurred, a melt with a higher silica content results.
pegmatite
vein deposits of extremely large-grained minerals that can contain rare ores such as lithium and beryllium
Porphyry
large and small crystals due to a change in the cooling rate of the rock
quartz
mineral that crystallizes last in Bowen’s reaction series. Will usually form in veins due to being “squeezed” between crystals
Rhyolitic Magma
High silica, lots of gas, high viscosity, very explosive.
silica
a material found in magma that is formed from the elements oxygen and silicon
temperature, pressure, water content, mineral content
four factors that affect the formation of magma
Ultramafic
Igneous rocks with low silica content and very high levels of magnesium and iron. Periodite, dunites, and doirite are examples.
Vesicular igneous rocks
Rocks that cool very quickly and gas bubbles are trapped
Has a spongy, porous texture
