RocksRocks

Ch 5 CP/GHP BookCh 5 CP/GHP Book

Extrusive igneous rocks form on or near the surface.

Intrusive igneous rocks form below the surface.

What are Igneous Rocks?

What are Igneous Rocks?

• Form from crystallized magma (lava = magma that flowed out onto Earth’s surface)

• Ignis is Latin for “fire”• Extrusive (fine-grained, cool quickly)• Intrusive (course-grained, cool slowly)

• Form from crystallized magma (lava = magma that flowed out onto Earth’s surface)

• Ignis is Latin for “fire”• Extrusive (fine-grained, cool quickly)• Intrusive (course-grained, cool slowly)

Magma CompositionMagma Composition

• O, Si, Al, Fe, Mg, Ca, K and Na

• 96% of Earth’s crust is silica (SiO2)

• Types of magmaRhyolitic 70%SiO2

Andesitic 60%SiO2

Basaltic 50%SiO2

• O, Si, Al, Fe, Mg, Ca, K and Na

• 96% of Earth’s crust is silica (SiO2)

• Types of magmaRhyolitic 70%SiO2

Andesitic 60%SiO2

Basaltic 50%SiO2

Magma OriginMagma Origin

• Melting temperatures: 800°C-1200°C• Temperature, pressure, chemical

composition and water content all affect magma

• Types of Magma

• Melting temperatures: 800°C-1200°C• Temperature, pressure, chemical

composition and water content all affect magma

• Types of MagmaQuickTime™ and a

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Magma OriginMagma Origin

• Geothermal gradient (page 101)

• Geothermal gradient (page 101)

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Magma OriginMagma Origin

• Melting curve (page 102)

• Melting curve (page 102)

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Pause for lab or demoPause for lab or demo

• Bowen’s reaction seriesmelting point of various itemscrystallization point of the same items

• Materials:Red, orange and yellow crayonsChocolate chipsLots of gummy bearsCandlesIceHot plate

• Bowen’s reaction seriesmelting point of various itemscrystallization point of the same items

• Materials:Red, orange and yellow crayonsChocolate chipsLots of gummy bearsCandlesIceHot plate

Results from the lab/demo

Results from the lab/demo

• Ice begins to melt at 32˚F

• Chocolate 70-97˚F

• M&M candy shell 98.6˚F

• Gummy bears 115˚F

• Candles 130˚F

• Crayons 145-160˚F

• Ice begins to melt at 32˚F

• Chocolate 70-97˚F

• M&M candy shell 98.6˚F

• Gummy bears 115˚F

• Candles 130˚F

• Crayons 145-160˚F

How rocks meltHow rocks melt

• Partial Melting – process when some minerals melt while others remain solid

• Fractional Crystallization – cooling in the reverse order of melting

• Partial Melting – process when some minerals melt while others remain solid

• Fractional Crystallization – cooling in the reverse order of melting

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Bowen’s Reaction Series

Bowen’s Reaction Series

• Geologist Neil L. Bowenminerals form in predictable patterns

• Geologist Neil L. Bowenminerals form in predictable patterns

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Bowen’s Reaction Series

Bowen’s Reaction Series

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Classifying Igneous Rocks Ch 5.2

Classifying Igneous Rocks Ch 5.2

• Mineral CompositionFelsic - light colored rocks such as graniteIntermediate - medium colored, andesiteMafic – dark colored rocks such as basaltUltramafic – very high levels of iron, low silica

• Mineral CompositionFelsic - light colored rocks such as graniteIntermediate - medium colored, andesiteMafic – dark colored rocks such as basaltUltramafic – very high levels of iron, low silica

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Classifying Igneous Rocks

Classifying Igneous Rocks

• Grain Size• Grain Size

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Classifying Igneous Rocks

Classifying Igneous Rocks

• Texture Phaneritic (A)- same size crystals throughoutPorphyritic (B)- large crystals surrounded by finer-grained crystals

• Texture Phaneritic (A)- same size crystals throughoutPorphyritic (B)- large crystals surrounded by finer-grained crystals

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Igneous rocks as resourcesIgneous rocks as resources

• Ore Deposits• Veins and Pegmatites

• Ore Deposits• Veins and Pegmatites QuickTime™ and a

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Igneous rocks as resourcesIgneous rocks as resources

• Kimberlites - ultramafic rocks of peridotite that can contain diamonds

• Kimberlites - ultramafic rocks of peridotite that can contain diamonds

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