REMINDER - CCSFkwiese/content/Classes/IgneousRocksPPT.pdfBrainstorm all igneous rock textures,...

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REMINDER

2 chapters covered next weekSedimentary Rocks

Soils and Weathering (first half)Learn vocabulary for both!

Turn to Neighbor:

Without using your book or notes, try to remember which silicate mineral is made of :

Independent tetrahedra?Single-chains?

Double-chains?Sheets?

3-D Framework?

Which of the above has the most Silica? Least?

What are these large minerals from the Museum of Natural History, NY? (About 4 feet tall!)

MOVIE: Rocks that Originate

Underground5:41 to 12:40

Igneous Rocks are classified by …………..

Porphyritictexture is a subcategory of Aphanitic

Pegmatitictexture is a subcategory

of Phaneritic

Volcanic TuffPumiceObsidianRhyoliteGraniteFelsic

Volcanic TuffPumiceAndesiteDioriteInter-mediate

Volcanic TuffScoriaBasaltGabbroMafic

PeridotiteUltramafic

Pyroclastic or fragmental

Frothy (glassy & vesicular)

GlassyAphaniticPhaneriticComposi-tion

Texture

2

> 65% silica

55 – 65% silica

45 – 55% silica

< 45% silica

Extrusive rock names

Intrusive rock names

Mineral composition

NameCompo-sition

Felsic> 65% silica

Interme-diate

55 – 65% silica

Mafic45 – 55% silica

Ultramafic< 45% silica



Mineral composition

NameCompo-sition

Felsic> 65% silica

Interme-diate

55 – 65% silica


Mostly OlivineMinor PyroxeneMinor Plagioclase




Mineral composition

NameCompo-sition

Felsic> 65% silica

Interme-diate

55 – 65% silica

PyroxeneCa-rich PlagioclaseMinor OlivineMinor Hornblende






Mineral composition

NameCompo-sition

Felsic> 65% silica

HornblendeBiotiteNa-rich PlagioclaseMinor Pyroxene

Interme-diate

55 – 65% silica







Mineral composition

NameCompo-sition

QuartzK-FeldsparMuscoviteMinor BiotiteMinor HornblendeMinor Na-rich Plagiocl.

Felsic> 65% silica

HornblendeBiotiteNa-rich PlagioclaseMinor Pyroxene

Interme-diate

55 – 65% silica







Mineral composition

NameCompo-sition

Rhyolite, Pumice, Tuff, Obsidian

GraniteQuartzK-FeldsparMuscoviteMinor BiotiteMinor HornblendeMinor Na-rich Plagiocl.

Felsic> 65% silica

Andesite, Pumice, Tuff

DioriteHornblendeBiotiteNa-rich PlagioclaseMinor Pyroxene

Interme-diate

55 – 65% silica

Basalt, ScoriaGabbroPyroxeneCa-rich PlagioclaseMinor OlivineMinor Hornblende


NONE EXIST ON PLANET EARTH

PeridotiteMostly OlivineMinor PyroxeneMinor Plagioclase




Mineral composition

NameCompo-sition



of Phaneritic








Texture

Phaneritic Phaneritic

3

Aphanitic

Pyroclastic Pyroclastic

4

Frothy Frothy

Tongariro National Park – Mt. Ngauruhoe

PUMICE FLOATING MOVIE

Glassy

Glassy



of Phaneritic








Texture

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Turn to Neighbor:

Come up with a good definition (no books or notebooks) of VISCOSITY.

Which is more viscous:

Water or Honey?Hot syrup or cold syrup?

DEMO: Oil Viscosity

Highly Viscous Felsic Lava

Low-Viscosity Mafic Lava

Mineral GrowthANIMATION

Phaneritic

Museum of Natural History, NY. – Rare minerals from PegmatitesAs molten granite crystallizes, the melt that remains becoems enriched in water and rare elements such as B, Ta, and Nb. These elements concentrate in the melt because they are not taken up by the minerals crystallizing from it. Eventually, enough water builds up that steam forms. Gem and ore minerals containing rare elements form in

the pockets of steam-and water-rich melt. In the presence of water, minerals can grow to enormous sizes.

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Pegmatite Vein – Filled In – Sierra Nevada Mountains Grand Canyon Pegmatite

(at the bottom!)

Tourmaline Mine Pegmatite San Diego

Glassy Glassy

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of Phaneritic








Texture

Assimilation – Sierra Nevada Mountains – Desolation Wilderness

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1:2QuartzNoneThree dimensional framework of Si-O tetrahedrons with no ionic bonds.

1:2Feldspars2 planes at 90° (square tablets)

Three dimensional framework of Si-O tetrahedrons with ionic bonds filling holes within.

1:2.5Micas1 plane Sheets connected to other sheets by ionic bonds.

1:2.75Hornblende2 planes at 60 and 120° (sheared columns) or hairs/fibers

Double chains connected to other chains by ionic bonds.

1:3Pyroxene2 planes at 90° (square columns) or hairs/fibers

Single chains connected to other chains by ionic bonds.

1:4OlivineNoneSingle Si-O tetrahedron connected to other tetrahedron by ionic bonds.

Si:O ratioExamplesCleavage typeSilicate structure

Plagioclase content

Olivine content

Quartz content

Water content

ViscosityFe, Mg, Ca content

Si, K, Na content

Temper-ature

Moves from Ca-rich to Na-rich

Plagioclase content↓Olivine

content↑Quartz content↑Water

content

↑Viscosity↓Fe, Mg, Ca content ↑Si, K, Na

content↓Temper-ature

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1:2QuartzNoneThree dimensional framework of Si-O tetrahedrons with no ionic bonds.

1:2Feldspars2 planes at 90° (square tablets)

Three dimensional framework of Si-O tetrahedrons with ionic bonds filling holes within.

1:2.5Micas1 plane Sheets connected to other sheets by ionic bonds.

1:2.75Hornblende2 planes at 60 and 120° (sheared columns) or hairs/fibers

Double chains connected to other chains by ionic bonds.

1:3Pyroxene2 planes at 90° (square columns) or hairs/fibers

Single chains connected to other chains by ionic bonds.

1:4OlivineNoneSingle Si-O tetrahedron connected to other tetrahedron by ionic bonds.

Si:O ratioExamplesCleavage typeSilicate structure



of Phaneritic








Texture

Turn to Neighbor:

Brainstorm all igneous rock textures, names, characteristics, etc. that are associated with

Extrusive rocks onlyIntrusive rocks only

(Make two columns on paper and decide where to place each thing so far discussed or read)

Rock names

Textures and features

DefinitionIntrusive or plutonicExtrusive or volcanic

Rock names


Magma that remains underground where it cools

Lava erupted and cooled at surface


Rock names

VesiclesAphaniticPorphyriticGlassyFrothyPyroclastic





ScoriaPumiceBasaltAndesiteRhyoliteVolcanic TuffObsidian

Rock names







Rock names

PhaneriticPegmatitic






PeridotiteGabbroDioriteGranite


Rock names

PhaneriticPegmatitic






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PlutonFormation

ANIMATION

Size

Shape: tabular or massive

Parallel to surrounding bedding (concordant) or cross-cutting (discordant)

BatholithDikeSill

5-30 m thickSize

TabularShape: tabular or massive

ParallelParallel to surrounding bedding (concordant) or cross-cutting (discordant)

BatholithDikeSill

0.5-30 m thick5-30 m thickSize

TabularTabularShape: tabular or massive

Cross-cuttingParallelParallel to surrounding bedding (concordant) or cross-cutting (discordant)

BatholithDikeSill

100s of km wide0.5-30 m thick5-30 m thickSize

MassiveTabularTabularShape: tabular or massive

Cross-cuttingCross-cuttingParallelParallel to surrounding bedding (concordant) or cross-cutting (discordant)

BatholithDikeSill

Basalt Sills – Glacier National Park

Basalt Dike – Mt. Moran – Grand Tetons

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Shiprock Peak in New Mexico Shiprock Peak in New Mexico

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Magma Mixing – Granite and Diorite

Cabo San Lucas, Mexico

We have now completed this week’s question sheet.

On your own, review each question again. I recommend that you write out your answers

(synthesize your thoughts and notes and put the answers into your own words).

If something doesn’t make sense or to just get some feedback, come see the tutors or me during my office

hours.

Remember: half of next week’s quiz will contain any question from the question sheet.

Rock ID Activity

Recommend setting samples up into 5 texture columns and 4 compositional rows, just like on naming table. ALSO – set up the Bowens Reaction Series minerals alongside the rocks, so you can see how they match.

There are some duplicate names in the boxes.

REMINDER - CCSFkwiese/content/Classes/IgneousRocksPPT.pdfBrainstorm all igneous rock textures,...

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