Transcript 18.3 power point - Trimble County Schools

Main Idea Magma Eruption
• 1. Does all magma erupt at the surface?
Main Idea Magma Eruption
• 2. Why does it matter where magma
erupts or where it cools?
Main Idea Magma Eruption
• 3. How could you tell if there were an
active magma intrusion below the surface?
18.3 – Intrusive Activity
http://3dparks.wr.usgs.gov/2005/lakemead/images/volcanic.gif
Plutons
http://www.geo.hunter.cuny.edu/bight/images/pluton.jpg
• Intrusive igneous rock body, including
batholiths, stocks,sills & dikes
• Formed through mountain-building
processes and oceanic-oceanic collisions
• Can be exposed at Earth’s surface to uplift
and erosion
Batholiths & Stocks
• The largest plutons are called Batholiths.
• Batholiths are coarse-grained, irregularly
shaped, igneous rock mass that covers at
least 100 km2
• Stocks are irregularly shaped plutons but
smaller in size.
• Both generally form 5-30 km below Earth’s
surface and are common in the interior of
major mountain chains
Laccoliths
• Relatively small
• Mushroom-shaped pluton that forms when
magma intrudes into parallel rock layers
close to Earth’s surface
• Laccoliths have
flat bottoms and
curved tops.
http://www.indiana.edu/~geol105/images/gaia_chapter_5/dike&sill.jpg
Sills
• Pluton that forms when magma intrudes
parallel rock layers
http://www.austmus.gov.au/geoscience/images/earth_diagrams/volcano_structure.gif
Dikes
• Pluton that cuts across preexisting rocks
and often forms when magma invades
cracks in surrounding rock bodies
http://www.waipahums.k12.hi.us/eportfolio05-06/wisportfolio05-06/team8d_portfolios/y_kenneth_e_portfolio/volcano_files/image002.png
Plutons & Tectonics
• Many plutons form as the result of
mountain-building processes.
• Plutons are thought to form as a result of
continental-continental and oceaniccontinental convergence.
Reinforcement
• T/F
• Batholiths are common in the interiors of
mountain chains.
• Laccoliths have curved bottoms and flat
tops.
• Sills form when magma is forced between
rock layers.
• Most igneous activity occurs deep within
earth.