Igneous Structures: Intrusive

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Igneous Structures Intrusive
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Viscosity

• Units pascal-seconds (kg/m-sec)
• How many pascals pressure x how many seconds to
  squash fluid flat?
• Viscous Material flows as long as pressure is
  applied, however small
• Pseudoviscous Material flows after some
  threshold stress

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Viscosity of Common Materials
Material Viscosity Pa-Sec
Hydrogen gas, 15 degrees K 0.0000006 (6 x 10-7)
Air, 0 degrees C 0.000017 (1.7 x 10-5)
Liquid Hydrogen 0.00001 (10-5)
Water 0 degrees C 0.0018 (1.8 x 10-3)
Water 100 degrees C 0.0003 (3 x 10-4)
Heavy Machine Oil 15 C 0.66
Glycerin, 20 degrees C 1.5
Honey 20 degrees C 1.6
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Geologic Viscosities
Material Viscosity Pa-Sec
Basalt Lava 1000
Rhyolite Lava 1,000,000
Rock Salt 1014 (Pseudoviscous)
Marble 1016
Granite, Quartzite 1018 - 1020
Asthenosphere 1019 - 1020
Deep Mantle 1021 - 1022
Shallow Mantle 1023 - 1024
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What Drives Magma?

• Magma is typically 10 lighter than equivalent
  solid rock
• Why pressure inhibits melting
• Buoyancy drives magma upward
• Weight of rock around volcanic conduit gt weight
  of magma
• Gas pressure powers volcanic eruptions
• Mafic (dense) rocks can sink in crust by viscous
  flow

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Plate Tectonics and Volcanoes
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Cullain Layered Complex, Scotland
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Cullain Layered Complex, Scotland
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Cullain Layered Complex, Scotland
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Cullain Layered Complex, Scotland
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Cullain Layered Complex, Scotland
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Filter Pressing, Scotland
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Filter Pressing? Scotland
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Lava Flows and Dike, Scotland
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Magma Mixing, Scotland
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Pseudotachylite, Scotland
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Sill, Scotland
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Extrusion Striae, Scotland
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Keeweenawan Sills, Ontario
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Keeweenawan Sills, Ontario
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Columnar Jointing, Ontario
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Batholith, California
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Sierra Nevada Batholith
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Roof Pendants, Sierra Nevada
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Columnar Jointing, Devils Postpile, California
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Columnar Jointing, Devils Postpile, California
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Columnar Jointing, Idaho
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Columnar Jointing, Scotland
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Devils Tower, Wyoming
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Phonolite, Devils Tower, Wyoming
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Jointing, Devils Tower, Wyoming
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Laccolith, Bear Mountain SD
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Laccolith, Wyoming
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How Laccoliths Form
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How Devils Tower Formed
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Intrusions, Mount Rushmore
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A Rarely Seen Perspective
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Granite Intrusion, Black Hills
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Dike and Shear Zone, Washington
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Dikes, Lead, South Dakota
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Dike, Redgranite, Wisconsin
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Dike, Redgranite, Wisconsin
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Dike, Black Hills, SD
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Palisades, New Jersey
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The Palisades
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Base of Palisades Sill, NJ
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Intrusion Breccia