geol101 2009lect05 volcanos - west virginia...
Post on 17-Mar-2018
213 Views
Preview:
TRANSCRIPT
GEOL 101 Lecture 5Dr. J. Steven Kite
West Virginia University
Volcanoes
““VolcanoVolcano””
19791979 Songs You Know by HeartSongs You Know by Heart
Jimmy Jimmy
BuffettBuffett
Spring Study Abroad Fair
Office of International Programs invites students to
WVU’s 2009 Spring Study Abroad Fair10 a.m.-4 p.m. Jan. 28
Mountainlair ballrooms.The fair will feature study abroad programs,
and faculty leaders and OIP staff will be on hand to answer questions. There will be door prizes
Start Working on Test Questions are available on my web
sitehttp://www.geo.wvu.edu/~kite/teaching.htm
Bring “Magma Chamber”(Lava Lamp)
Volcanoes:• Composition of Magma:
Important To Nature of Volcanic Eruptions and Resulting Landforms.
3 Eruption Types:
• Gaseous: Few Landforms• Explosive: Viscous Magma -• Effusive: Fluid Magma -Basaltic - Lava
3 Eruption Types:
• Gaseous: Few Landforms
Explosive Eruption:
Pyroclastics
Pinatubo, Philippines
1991
Fluid BasalticLava FlowMauna Loa, March 1983
Magma Viscosity Analog
2 Types of Eruption Apertures:
•Fissures•Vents
Basaltic Fissure Eruption, Hawaii 1983
Popocatepetl, Mexico: 1994
Fissure Eruptions• Basaltic: Fluid Lava
– Flood Basalts With Many Feeder Dikes; Basalt Plateaus
Columnar Jointing
Columnar Jointing, Yellowstone NP Lava Flow• J.S. Kite Photo, 2008
Dry Falls, Washington
Vent Eruptions = True Volcanoes
Basaltic Eruptions: Fluid Lava
• Shield Volcano (Hawaiian) -Flank Eruptions
• Hawaii 33,000 ft Relief; Olympus Mons = 80,000 ft
• Late Eruptions from MaficMagma Chamber may be Viscous
Basaltic Shield VolcanoMauna Kea, Hawaii
Shield Volcano
Basaltic Lava Flow
Shield Volcano: Mauna Loa, Hawaii
Mauna Loa Central Vent, Mauna Kea in Distance
Kupaianaha Shield, 1986
Pu’u O’o Lava Tube, 1992
Lava Tube, Hawaiian Volcanoes
National Park
Pu’u O’o - Royal Gardens Aa Flow 1983
Kilauea Eruptions 1983-Date
181 Houses Destroyed13 km of Road Buried
Pu’u O’o - Royal Gardens Aa Flow 1983
Kupaianaha Flow Meets Pacific, 1988
Rhyolitic Eruptions:Viscous Magma &
Pyroclastics
• Cinder Cones• Lava Domes• Minor Lava Flows
Tavurvur Volcano, New Guinea: Cinder Cone, Pyroclastics
Ashfall, Papua New Guinea, 1994
Cinder Cone: Mt. Etna, Italy
Viscous (Rhyolitic) Magma
Post-1980 Lava Dome
Mt. St. Helens
May Occur in Late Eruption Phases of Intermediate Magma Chamber
Intermediate (Andesitic) Magma:
Composition Varies -Viscous to Fluid• Small Cinder Cones & Flows
Grow into....• Composite Cones
(=Stratovolcanos) –Composite of Flows & Pyroclastics
Soufriere Hills
VolcanoMontserrat
Plymouth, Montserrat, July 1997
Bethel, Montserrat, July 1997
Mt. St. Helens, Spirit Lake
America’s Most Perfect Volcano
Mt. St. Helens, April 1980 Bulge
Mt. St. Helens Pyroclastics
1980
New Spirit Lake
Blast Zone of Mt. St. Helens
Eruption Casualty
Mt. Rainier & Tacoma, WA
Popocatepetl, Mexico: 1994
Popocatepetl, Mexico: Dec 2000
Caldera:Collapse of Magma Chamber
Positive Feed Back System:Lower Pressure = Eruption;Eruption = Lower Pressure
• Krakatoa 1883 • Mt. Mazama - Crater Lake
Crater Lake: Caldera of Mt Mazama
Caldera Eruptions• Welded Sheet of Tephra Includes
Ash, Bombs etc.
Mt. MazamaTephra orPyroclastics
Aniakchak Caldera, Alaska
Erosion -• Volcanic Neck Usually More
Resistant To Erosion • Erosion often Simultaneous
with Eruption -–Complex Forms
Shiprock, New Mexico
http://www.lavaworld.com/cfm/catalog/productlist.cfm©2000 Haggerty Enterprises, Inc., Chicago, Illinois
Magma Chamber Model
Pluton
• Igneous Intrusion–May Not Connect to Volcanos
• Large Pluton Cool Very Slow -Coarse-Grained Rx
• Small Plutons Cool Rapidly -Fine Grained Rx
Igneous Plutons
Plutons• Batholith - Huge• Stock - Big• Dike - Across Country Rock Layering• Sill - Parallel Country Rock Layering• Laccolith - Igneous “Blister”• Pipe or Neck- Feeder Tube
Igneous Plutons
Igneous Dikes
Finger Mountain Sill Jurassic “Basalt”
Upper Taylor Glacier, Antarctica ~ 200 m thick
intruded into Sandstone
Photo: Bernard M.Gunn, 1959www.geokem.com/images/pix/G-FDOL.jpg
See Web for Copyrighted Image
Devils Tower, Wyoming: Eroded Laccolith, J.S. Kite Photo, 2006
Long Valley Batholith & Dikes
top related