intrusive igneous rocks form when magma cools within existing rocks in earth’s crust. extrusive...
TRANSCRIPT
![Page 1: Intrusive igneous rocks form when magma cools within existing rocks in Earth’s crust. Extrusive igneous rocks form when magma cools on Earth’s surface,](https://reader036.vdocuments.site/reader036/viewer/2022081506/56649d145503460f949e8798/html5/thumbnails/1.jpg)
![Page 2: Intrusive igneous rocks form when magma cools within existing rocks in Earth’s crust. Extrusive igneous rocks form when magma cools on Earth’s surface,](https://reader036.vdocuments.site/reader036/viewer/2022081506/56649d145503460f949e8798/html5/thumbnails/2.jpg)
![Page 3: Intrusive igneous rocks form when magma cools within existing rocks in Earth’s crust. Extrusive igneous rocks form when magma cools on Earth’s surface,](https://reader036.vdocuments.site/reader036/viewer/2022081506/56649d145503460f949e8798/html5/thumbnails/3.jpg)
Intrusive igneous rocks form when magma cools within existing rocks in Earth’s crust.
Extrusive igneous rocks form when magma cools on Earth’s surface, where they have been “extruded.”
![Page 4: Intrusive igneous rocks form when magma cools within existing rocks in Earth’s crust. Extrusive igneous rocks form when magma cools on Earth’s surface,](https://reader036.vdocuments.site/reader036/viewer/2022081506/56649d145503460f949e8798/html5/thumbnails/4.jpg)
The two most obvious textural features of an igneous rock are the size of its mineral grains and how the mineral grains are packed together.
![Page 5: Intrusive igneous rocks form when magma cools within existing rocks in Earth’s crust. Extrusive igneous rocks form when magma cools on Earth’s surface,](https://reader036.vdocuments.site/reader036/viewer/2022081506/56649d145503460f949e8798/html5/thumbnails/5.jpg)
• Intrusive rocks are coarse-grained. Magma that solidifies in the crust cools slowly and has sufficient time to
form large mineral grains.
Extrusive rocks are fine-grained. Magma that solidifies on the surface usually cools rapidly, allowing
insufficient time for large crystals to grow.Coarse-grained igneous rock is called a phanerite (from the Greek word meaning visible).Igneous rock that contains unusually large mineral grains (2cm or larger) is called a pegmatite.Fine-grained igneous rock is called an aphanite (from the Greek word meaning invisible).
- Factors: cooling rate and viscosity
![Page 6: Intrusive igneous rocks form when magma cools within existing rocks in Earth’s crust. Extrusive igneous rocks form when magma cools on Earth’s surface,](https://reader036.vdocuments.site/reader036/viewer/2022081506/56649d145503460f949e8798/html5/thumbnails/6.jpg)
Granite RhyoliteFigure 4.7 A
![Page 7: Intrusive igneous rocks form when magma cools within existing rocks in Earth’s crust. Extrusive igneous rocks form when magma cools on Earth’s surface,](https://reader036.vdocuments.site/reader036/viewer/2022081506/56649d145503460f949e8798/html5/thumbnails/7.jpg)
DioriteAndesite
Figure 4.7 B
![Page 8: Intrusive igneous rocks form when magma cools within existing rocks in Earth’s crust. Extrusive igneous rocks form when magma cools on Earth’s surface,](https://reader036.vdocuments.site/reader036/viewer/2022081506/56649d145503460f949e8798/html5/thumbnails/8.jpg)
Gabbro Basalt
Figure 4.7 C
![Page 9: Intrusive igneous rocks form when magma cools within existing rocks in Earth’s crust. Extrusive igneous rocks form when magma cools on Earth’s surface,](https://reader036.vdocuments.site/reader036/viewer/2022081506/56649d145503460f949e8798/html5/thumbnails/9.jpg)
• The isolated large grains are phenocrysts.
![Page 10: Intrusive igneous rocks form when magma cools within existing rocks in Earth’s crust. Extrusive igneous rocks form when magma cools on Earth’s surface,](https://reader036.vdocuments.site/reader036/viewer/2022081506/56649d145503460f949e8798/html5/thumbnails/10.jpg)
Glassy rocks.Extrusive igneous rocks that are largely or whollyglassy are called obsidian.They display a distinctiveconchoidal fracture (smooth, curved surface).
![Page 11: Intrusive igneous rocks form when magma cools within existing rocks in Earth’s crust. Extrusive igneous rocks form when magma cools on Earth’s surface,](https://reader036.vdocuments.site/reader036/viewer/2022081506/56649d145503460f949e8798/html5/thumbnails/11.jpg)
Once the texture of an igneous rock is determined, its name will depend on its mineral assemblage. All common igneous rocks consist largely of:Quartz. FeldsparMicaAmphibole.Pyroxene.Olivine.
![Page 12: Intrusive igneous rocks form when magma cools within existing rocks in Earth’s crust. Extrusive igneous rocks form when magma cools on Earth’s surface,](https://reader036.vdocuments.site/reader036/viewer/2022081506/56649d145503460f949e8798/html5/thumbnails/12.jpg)
The overall lightness or darkness of a rock is a valuable indicator of its makeup.FELSIC Light-colored rocks are:
Quartz. Feldspar. Muscovite.
MAFIC Dark-colored rocks are:Biotite. Amphibole. Pyroxene.
![Page 13: Intrusive igneous rocks form when magma cools within existing rocks in Earth’s crust. Extrusive igneous rocks form when magma cools on Earth’s surface,](https://reader036.vdocuments.site/reader036/viewer/2022081506/56649d145503460f949e8798/html5/thumbnails/13.jpg)
Felsic Intermediate Mafic
Granite Diorite Gabbro
Rhyolite Andesite Basalt
(Porphyritic)
Intr
usi
veE
xtru
sive
![Page 14: Intrusive igneous rocks form when magma cools within existing rocks in Earth’s crust. Extrusive igneous rocks form when magma cools on Earth’s surface,](https://reader036.vdocuments.site/reader036/viewer/2022081506/56649d145503460f949e8798/html5/thumbnails/14.jpg)
Figure 5.7Figure 5.7
![Page 15: Intrusive igneous rocks form when magma cools within existing rocks in Earth’s crust. Extrusive igneous rocks form when magma cools on Earth’s surface,](https://reader036.vdocuments.site/reader036/viewer/2022081506/56649d145503460f949e8798/html5/thumbnails/15.jpg)
All bodies of intrusive igneous rock, regardless of shape or size, are called plutons, after Pluto, the Greek god of the underworld.
Plutons are given special names depending on their shapes and sizes.
![Page 16: Intrusive igneous rocks form when magma cools within existing rocks in Earth’s crust. Extrusive igneous rocks form when magma cools on Earth’s surface,](https://reader036.vdocuments.site/reader036/viewer/2022081506/56649d145503460f949e8798/html5/thumbnails/16.jpg)
Figure 4.11
![Page 17: Intrusive igneous rocks form when magma cools within existing rocks in Earth’s crust. Extrusive igneous rocks form when magma cools on Earth’s surface,](https://reader036.vdocuments.site/reader036/viewer/2022081506/56649d145503460f949e8798/html5/thumbnails/17.jpg)
![Page 18: Intrusive igneous rocks form when magma cools within existing rocks in Earth’s crust. Extrusive igneous rocks form when magma cools on Earth’s surface,](https://reader036.vdocuments.site/reader036/viewer/2022081506/56649d145503460f949e8798/html5/thumbnails/18.jpg)
Tephra can be converted into pyroclastic rock in two ways:Through the addition of a cementing agent, such as
quartz or calcite, introduced by groundwater.Through the welding of hot, glassy, ash particles.
Welded tuff.
![Page 19: Intrusive igneous rocks form when magma cools within existing rocks in Earth’s crust. Extrusive igneous rocks form when magma cools on Earth’s surface,](https://reader036.vdocuments.site/reader036/viewer/2022081506/56649d145503460f949e8798/html5/thumbnails/19.jpg)
![Page 20: Intrusive igneous rocks form when magma cools within existing rocks in Earth’s crust. Extrusive igneous rocks form when magma cools on Earth’s surface,](https://reader036.vdocuments.site/reader036/viewer/2022081506/56649d145503460f949e8798/html5/thumbnails/20.jpg)
![Page 21: Intrusive igneous rocks form when magma cools within existing rocks in Earth’s crust. Extrusive igneous rocks form when magma cools on Earth’s surface,](https://reader036.vdocuments.site/reader036/viewer/2022081506/56649d145503460f949e8798/html5/thumbnails/21.jpg)
![Page 22: Intrusive igneous rocks form when magma cools within existing rocks in Earth’s crust. Extrusive igneous rocks form when magma cools on Earth’s surface,](https://reader036.vdocuments.site/reader036/viewer/2022081506/56649d145503460f949e8798/html5/thumbnails/22.jpg)
![Page 23: Intrusive igneous rocks form when magma cools within existing rocks in Earth’s crust. Extrusive igneous rocks form when magma cools on Earth’s surface,](https://reader036.vdocuments.site/reader036/viewer/2022081506/56649d145503460f949e8798/html5/thumbnails/23.jpg)
![Page 24: Intrusive igneous rocks form when magma cools within existing rocks in Earth’s crust. Extrusive igneous rocks form when magma cools on Earth’s surface,](https://reader036.vdocuments.site/reader036/viewer/2022081506/56649d145503460f949e8798/html5/thumbnails/24.jpg)
![Page 25: Intrusive igneous rocks form when magma cools within existing rocks in Earth’s crust. Extrusive igneous rocks form when magma cools on Earth’s surface,](https://reader036.vdocuments.site/reader036/viewer/2022081506/56649d145503460f949e8798/html5/thumbnails/25.jpg)
A magma of a given composition can crystallize into many different kinds of igneous rock.
Solidifying magma forms several different minerals which start to crystallize from the cooling magma at different temperatures.
![Page 26: Intrusive igneous rocks form when magma cools within existing rocks in Earth’s crust. Extrusive igneous rocks form when magma cools on Earth’s surface,](https://reader036.vdocuments.site/reader036/viewer/2022081506/56649d145503460f949e8798/html5/thumbnails/26.jpg)
Crystal-melt separation can occur in a number of ways:• Compression can squeeze melt out of a crystal-melt
mixture. • Dense, early crystallized minerals may sink to the
bottom of a magma chamber, thereby forming a solid mineral layer covered by melt.
However a separation occurs, the compositional changes it causes are called magmatic differentiation by fractional crystallization.
![Page 27: Intrusive igneous rocks form when magma cools within existing rocks in Earth’s crust. Extrusive igneous rocks form when magma cools on Earth’s surface,](https://reader036.vdocuments.site/reader036/viewer/2022081506/56649d145503460f949e8798/html5/thumbnails/27.jpg)
Canadian-born scientist N. L. Bowen (1887-1956) first recognized the importance of magmatic differentiation by fractional crystallization.
Bowen argued that a single magma could crystallize into both basalt and rhyolite because of fractional crystallization.
![Page 28: Intrusive igneous rocks form when magma cools within existing rocks in Earth’s crust. Extrusive igneous rocks form when magma cools on Earth’s surface,](https://reader036.vdocuments.site/reader036/viewer/2022081506/56649d145503460f949e8798/html5/thumbnails/28.jpg)
1200
oC
1000
o
Two series of minerals formed during crystallization of magma
Intrus. Extrus.
Gabbro Basalt
Diorite Andesite
Granite Rhyolite
Low Silica Magma
High Silica Magma
Fra
me-
D
oubl
e
S
ingl
e
Isol
ated
wor
k
S
heet
Cha
in
Cha
in
Temperature ofCrystallization
750
o
![Page 29: Intrusive igneous rocks form when magma cools within existing rocks in Earth’s crust. Extrusive igneous rocks form when magma cools on Earth’s surface,](https://reader036.vdocuments.site/reader036/viewer/2022081506/56649d145503460f949e8798/html5/thumbnails/29.jpg)
Figure 4.19 A
![Page 30: Intrusive igneous rocks form when magma cools within existing rocks in Earth’s crust. Extrusive igneous rocks form when magma cools on Earth’s surface,](https://reader036.vdocuments.site/reader036/viewer/2022081506/56649d145503460f949e8798/html5/thumbnails/30.jpg)
Figure 4.19 B
![Page 31: Intrusive igneous rocks form when magma cools within existing rocks in Earth’s crust. Extrusive igneous rocks form when magma cools on Earth’s surface,](https://reader036.vdocuments.site/reader036/viewer/2022081506/56649d145503460f949e8798/html5/thumbnails/31.jpg)
The solid olivine reacts with silica in the melt to form a more silica-rich mineral, pyroxene.
The pyroxene in turn can react to form amphibole.
Amphibole can react to form biotite. Such a series of reactions is called a
discontinuous reaction series.
![Page 32: Intrusive igneous rocks form when magma cools within existing rocks in Earth’s crust. Extrusive igneous rocks form when magma cools on Earth’s surface,](https://reader036.vdocuments.site/reader036/viewer/2022081506/56649d145503460f949e8798/html5/thumbnails/32.jpg)
Figure 4.20
![Page 33: Intrusive igneous rocks form when magma cools within existing rocks in Earth’s crust. Extrusive igneous rocks form when magma cools on Earth’s surface,](https://reader036.vdocuments.site/reader036/viewer/2022081506/56649d145503460f949e8798/html5/thumbnails/33.jpg)
Figure 4.21
![Page 34: Intrusive igneous rocks form when magma cools within existing rocks in Earth’s crust. Extrusive igneous rocks form when magma cools on Earth’s surface,](https://reader036.vdocuments.site/reader036/viewer/2022081506/56649d145503460f949e8798/html5/thumbnails/34.jpg)