GLY 150: Earthquakes and VolcanoesSpring 2005: 040605

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GLY 150 Earthquakes and VolcanoesSpring 2005
04/06/05
Lecture 21
Black Smoker
Ancient Bacteria
All from http//www.pbs.org/saf/1207/features/113.
htm
Tube Worms
Life at mid-ocean ridges
Shrimp
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AnnouncementsGLY 150 Earthquakes and Volcanoes

• The next journal assignment is due this Thurs.
  If you still have questions regarding the grading
  the grading criteria please see me or the T.A.
  (recent small magnitude earthquake in NMSZ)
• Instructor office hours are Mon. 200-300 and
  Wed. 200-300
  
• Remember, use your texts to supplement the
  lecture notes, especially as we start case
  studies next week. It will be impossible to
  cover all the material in the text but it will
  appear on exams and its actually interesting.

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Extra Credit OpportunityGLY 150 Earthquakes and
Volcanoes

• I have a list of events we have not studied in
  class. See Rachel or myself to find out the
  topics you will write about.
  
• For each talk, write a four page (single space,
  12 inch font, 1 inch margins) summary of the
  event, tectonic setting, its implications,
  reasons for damage and fatalities, related
  archeological evidence, etc. etc. and and receive
  4 bonus points added to your total exam score for
  the semester.
• Follow the directions closely or no credit will
  be given
  
• If you write two reports you will receive 8 bonus
  points
  
• For those of you who have written reports on one
  or both of the lectures, you may only accumulate
  8 bonus points total for the semester so if you
  have already accumulated your bonus points dont
  do this too. If you get less than 4 points on
  any of the assignments you can complete this
  project so as to account for points missed.
• The due date will very. You can choose to
  complete this assignment at any time for the
  remainder of the class. The assignment will be
  due 1 week after you are given a topic.

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Events this QuarterSpring 2005
Note Some of the eruptions may be ongoing so be
sure to check their current status
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The Mid-Ocean Ridge SystemTypes of Eruptions
http//www.gly.uga.edu/railsback/GeologicalDiagram
s1.html

• Magma rises from magma chambers to shallow depth
• Rising magma temporarily fills in cracks between
  spreading plates (a.k.a. sheeted dikes)
  
• Dike emplacement does not produce eruptions on
  the ocean floor
  
• Additional lava erupts onto ocean floor to form
  pillow basalts

Pillow Basalts
Sheeted Dikes
http//volcano.und.nodak.edu/vwdocs/Submarine/plat
es/diverg/fast.html
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Mid-Ocean Ridge VolcanismHydrothermal
Circulation of Ocean Water

• Seawater drawn into oceanic crust along the sides
  of rift
  
• As water approaches underlying magma chamber, it
  is heated
  
• Heated water dissolves various metals and other
  elements
  
• Heated water raises to surface (buoyancy)
  Ejected at submarine hot springs
  
• As water cooled by surrounding ocean,
• metals, etc. came out of
• solution and are
• precipitated
• Form black
• smokers
• Coat
• surrounding
• structures

http//oceanexplorer.noaa.gov/explorations/02fire/
background/vent_chem/media/chemistry.html
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Mid-Ocean Ridge VolcanismUnique Ecosystems
Tube Worms

• Heated water ejected at submarine hot springs
• Dissolved metals (especially sulfides) come out
  of solution making waters look black
  
• Bacteria derive energy of life from
  chemosynthesis (energy derived from chemical
  reactions) as opposed photosynthesis
  
• Supports incredible diverse ecosystem with
  well-developed food chain with animals large and
  small on otherwise barren ocean floor
  
• This may be how early life survived on Earth
  life survives on other planets

Black Smoker
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Quiz
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Quiz 9 Mid-Ocean Volcanism

• (1 point) The energy of life at black smokers is
  derived from
  
• sunlight
• chemosynthesis
• photosynthesis
• hydrogen
• food drifting down from the the surface
• (1 point) Volcanic activity at mid-ocean ridges
• is explosive
• induces very little hydrothermal circulation
• erupts magma initially stored in magma chambers
  at the core-mantle boundary
  
• never erupts lava onto the seafloor
• produces pillow basalts and sheeted dikes
• (2 points) Write 2-3 complete sentences discuss
  the relationships between biology and geology
  that have been discussed over the last few weeks
  (black smokers, atolls, kipukas, Galapagos
  Islands, etc.) Other comments are welcome but
  not required.

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FilmNOVA Volcanoes of the Deep1999