igneous rocks chap. 5 what are igneous rocks? identifying igneous rocks
TRANSCRIPT
Igneous RocksIgneous RocksChap. 5Chap. 5Chap. 5Chap. 5
• What are igneous rocks?• Identifying igneous rocks
What are igneous rocks? – 5.1
ObjectivesObjectives
• compare and contrast intrusive and extrusive rocks• describe the composition of magma• discuss the factors that affect how rocks melt and crystallize
Rhyolite breccia
I.I. DefinitionDefinition
Igneous Rocks Igneous Rocks
Rocks formed when magma crystallizes.Rocks formed when magma crystallizes.
‘‘Ignis’ = fireIgnis’ = fire
II.II.Types of Igneous rocksTypes of Igneous rocks
A.A. Extrusive – fine grained rocks that Extrusive – fine grained rocks that cool quickly, on Earth’s surfacecool quickly, on Earth’s surface
II.II.Types of Igneous rocksTypes of Igneous rocks
Basalt
B.B. Intrusive – Intrusive – -grained rocks -grained rocks that cool that cool , , the Earth the Earth
II.II.Types of Igneous rocksTypes of Igneous rocks
B.B. Intrusive – Intrusive – coarsecoarse-grained rocks -grained rocks that cool that cool slowlyslowly, , underunder the Earth the Earth
II.II.Types of Igneous rocksTypes of Igneous rocks
Granite
III.III. Magma compositionMagma composition
A.A. Molten rockMolten rock
III.III. Magma compositionMagma composition
A.A. Molten rockMolten rock
B.B. GasesGases
III.III. Magma compositionMagma composition
A.A. Molten rockMolten rock
B.B. GasesGases
C.C. Mineral crystalsMineral crystals
III.III. Magma compositionMagma composition
A.A. Molten rockMolten rock
B.B. GasesGases
C.C. Mineral crystalsMineral crystals
D.D. Magma ClassificationsMagma Classifications
III.III. Magma compositionMagma composition
A.A. Molten rockMolten rock
B.B. GasesGases
C.C. Mineral crystalsMineral crystals
D.D. Magma ClassificationsMagma Classifications
III.III. Magma compositionMagma composition
1.1. Basaltic – 50% SiOBasaltic – 50% SiO22
A.A. Molten rockMolten rock
B.B. GasesGases
C.C. Mineral crystalsMineral crystals
D.D. Magma ClassificationsMagma Classifications
III.III. Magma compositionMagma composition
1.1. Basaltic – 50% SiOBasaltic – 50% SiO22
2.2. Andesitic – 60% SiOAndesitic – 60% SiO22
A.A. Molten rockMolten rock
B.B. GasesGases
C.C. Mineral crystalsMineral crystals
D.D. Magma ClassificationsMagma Classifications
III.III. Magma compositionMagma composition
1.1. Basaltic – 50% SiOBasaltic – 50% SiO22
2.2. Andesitic – 60% SiOAndesitic – 60% SiO22
3.3. Rhyolitic – 70% SiORhyolitic – 70% SiO22
IV.IV. Magma Formation is Magma Formation is Influenced byInfluenced by
A.A. Temperature Temperature (increases with (increases with depth)depth)
IV.IV. Magma Formation is Magma Formation is Influenced byInfluenced by
A.A. Temperature (increases with depth)Temperature (increases with depth)
B.B. Pressure (as pressure Pressure (as pressure ↑, melting pt. ↑, melting pt. ↑)↑)
IV.IV. Magma Formation is Magma Formation is Influenced byInfluenced by
A.A. Temperature (increases with depth)Temperature (increases with depth)
B.B. Pressure (as pressure Pressure (as pressure ↑, melting pt. ↑, melting pt. ↑)↑)
C.C. HH22O content (more HO content (more H22O, melting pt. O, melting pt. ↓)↓)
IV.IV. Magma Formation is Magma Formation is Influenced byInfluenced by
A.A. Temperature (increases with depth)Temperature (increases with depth)
B.B. Pressure (as pressure Pressure (as pressure ↑, melting pt. ↑, melting pt. ↑)↑)
C.C. HH22O content (more HO content (more H22O, melting pt. O, melting pt. ↓)↓)
D.D. Mineral contentMineral content
IV.IV. Magma Formation is Magma Formation is Influenced byInfluenced by
Granite has higher water content Granite has higher water content so it melts at a so it melts at a temperature temperature
A.A. Temperature (increases with depth)Temperature (increases with depth)
B.B. Pressure (as pressure Pressure (as pressure ↑, melting pt. ↑, melting pt. ↑)↑)
C.C. HH22O content (more HO content (more H22O, melting pt. O, melting pt. ↓)↓)
D.D. Mineral contentMineral content
IV.IV. Magma Formation is Magma Formation is Influenced byInfluenced by
Granite has higher water content Granite has higher water content so it melts at a so it melts at a lowerlower temperature temperature
V.V. Melting RocksMelting Rocks
A.A. Partial meltingPartial melting
V.V. Melting RocksMelting Rocks
Some minerals melt while others remain solidSome minerals melt while others remain solid
A.A. Partial meltingPartial melting
V.V. Melting RocksMelting Rocks
Some minerals melt while others remain solidSome minerals melt while others remain solid
HEAT
A.A. Partial meltingPartial melting
B.B. Fractional crystallizationFractional crystallization
V.V. Melting RocksMelting Rocks
As liquid rock cools certain minerals crystallize As liquid rock cools certain minerals crystallize before othersbefore others
A.A. Partial meltingPartial melting
B.B. Fractional crystallizationFractional crystallization
V.V. Melting RocksMelting Rocks
As liquid rock cools certain minerals crystallize As liquid rock cools certain minerals crystallize before othersbefore others
COOLING
A chart that shows how minerals crystallize A chart that shows how minerals crystallize when cooledwhen cooled
VI.VI. Bowen’s SeriesBowen’s Series
A.A. Two pathsTwo paths
VI.VI. Bowen’s SeriesBowen’s Series
A.A. Two pathsTwo paths
VI.VI. Bowen’s SeriesBowen’s Series
1.1. Continuous path for feldsparsContinuous path for feldspars
A.A. Two pathsTwo paths
VI.VI. Bowen’s SeriesBowen’s Series
1.1. Continuous path for feldsparsContinuous path for feldspars
2.2. Stepwise path for Fe/Mg mineralsStepwise path for Fe/Mg minerals
A.A. Two pathsTwo paths
B.B. Both paths end with Si and O – the Both paths end with Si and O – the last minerals to crystallizelast minerals to crystallize
VI.VI. Bowen’s SeriesBowen’s Series
VI.VI. IntrusionsIntrusions
A.A. Quartz (SiOQuartz (SiO22) finds way into rock ) finds way into rock veinsveins
VI.VI. IntrusionsIntrusions
Quartz vein
A.A. Quartz (SiOQuartz (SiO22) finds way into rock ) finds way into rock veinsveins
B.B. Intruded masses of rock cool in Intruded masses of rock cool in layers, often carrying metals (gold, layers, often carrying metals (gold, silver, and platinum)silver, and platinum)
VI.VI. IntrusionsIntrusions
The End
Classifying Igneous Rocks 5.2
ObjectivesObjectives• Classify different types and textures of igneous rocks• Recognize the effects of cooling rates on the grain sizes• Describe some uses of igneous rocks
Basalt
I.I. Where rock formsWhere rock forms
I.I. Where rock formsWhere rock formsA.A. Intrusive forms Intrusive forms ..
I.I. Where rock formsWhere rock formsA.A. Intrusive forms Intrusive forms under surfaceunder surface..
B.B. Extrusive forms Extrusive forms ..
I.I. Where rock formsWhere rock formsA.A. Intrusive forms Intrusive forms under surfaceunder surface..
B.B. Extrusive forms Extrusive forms above surfaceabove surface..
II.II. Rock’s compositionRock’s composition
II.II. Rock’s compositionRock’s compositionA.A. Felsic – silicon-rich, light coloredFelsic – silicon-rich, light colored
Granite
II.II. Rock’s compositionRock’s compositionA.A. Felsic – silicon-rich, light coloredFelsic – silicon-rich, light colored
B.B. Mafic – iron & magnesium rich, Mafic – iron & magnesium rich, dark coloreddark colored
Gabbro
II.II. Rock’s compositionRock’s compositionA.A. Felsic – silicon-rich, light coloredFelsic – silicon-rich, light colored
B.B. Mafic – iron & magnesium rich, Mafic – iron & magnesium rich, dark coloreddark colored
C.C. Ultramafic – very high levels of Fe Ultramafic – very high levels of Fe & Mg& Mg
Peridotite
III.III. TextureTextureA.A. Phaneritic has coarse grainsPhaneritic has coarse grains
Granite
III.III. TextureTextureB.B. Aphanitic is fine-grainedAphanitic is fine-grained
Basalt
III.III. TextureTextureC.C. Vessicular – has tiny holesVessicular – has tiny holes
Vessicular Basalt
III.III. TextureTextureD.D. Glassy – has no visible grainsGlassy – has no visible grains
Obsidian
III.III. TextureTextureE.E. Porphyritic – has Porphyritic – has large grainslarge grains
surrounded by surrounded by smaller grainssmaller grains
Andesite
IV.IV. Igneous rocks as resourcesIgneous rocks as resources
IV.IV. Igneous rocks as resourcesIgneous rocks as resourcesA.A. They are strong and resist They are strong and resist
weatheringweathering
A.A. They are strong and resist They are strong and resist weatheringweathering
B.B. Granite is a common construction Granite is a common construction materialmaterial
IV.IV. Igneous rocks as resourcesIgneous rocks as resources
V.V. Ores Ores
Minerals that contain useful substances that Minerals that contain useful substances that are mined for profitare mined for profit
A.A. Important metallic elements often Important metallic elements often found near veinsfound near veins
V.V. Ores Ores
A.A. Important metallic elements often Important metallic elements often found near veinsfound near veins
B.B. PegmatitesPegmatites
V.V. Ores Ores
Veins of extremely large-grained mineralsVeins of extremely large-grained minerals
A.A. Important metallic elements often Important metallic elements often found near veinsfound near veins
B.B. PegmatitesPegmatites
C.C. KimberlitesKimberlites
V.V. Ores Ores
These contain diamondsThese contain diamonds
The End