G131 HOME
INFORMATION
SCHEDULE
RESOURCES
EXERCISES
NOTES
Links to summaries of key issues for each topic
PREAMBLE
Introduction
PART I
Ocean World
Plate Tectonics
Margins/Basins
Review 1
Sediments
Chemistry
PART II
Atmosphere
Ocean Circuln.
Waves
Tides
PART III
Coasts
Ocean Life
Primary Prodn.
Mar. Animals
Communities
Mar. Resources
Env. Concerns
VISUALS
Links to images employed in lectures
TEXT
Link to chapter outlines at online learning center
NOTES
Links to summaries of key issues for each topic
 
Plate Tectonics (contd.)   

Notes on Topic:

  • The notes identify the learning objectives within dominant themes
  • They present summaries of key issues for each topic
  • They emphasize the terminology used to describe the various phenomena.
3. Types of Plate Boundaries:
Learning Objectives:
  • Processes occurring at plate boundaries: rifting, subduction, collision.
  • Characteristics of different settings
Rifting:
  • Rifts in spreading zones at ocean/ocean divergence 
    • lithosphere is thin 
  • Stages of rift development: 
    • block faulting creates grabens (E. Africa), 
    • widens, and deepens, then lava eruptions - pillow basalts
    • seawater may enter (Red Sea), new ocean crust formed
  • Ridge structure: 
    • layered system of oceanic lithosphere 
    • sequence from surface to depth:
      • sediments, glassy lava and basalt dikes, gabbro, peridotite.
Subduction:
  • Plate collisions:
    • descending plate is that with density closest to asthenosphere
    • creates trench and volcanic activity 
    • forms steep sided, cone-shaped stratovolcanoes
    • ocean/continent: explosive andesite volcanoes on continents 
      • Andes, Cascades, volcanic arcs
    • ocean/ocean islands arcs with explosive ash volcanism 
      • Aleutians, Japan, Philippine 
    • continental collisions create mountains by folding, thrusting and thickening crust 
      • Himalayas, Alps
Volcanic Actvity :
  • 3 types of Volcanism
  • Divergent boundaries: 
    • pillow lavas within rift of spreading ridge (e.g. Juan de Fuca)
  • Convergent boundaries: 
    • arc volcanoes (stratovolcanoes) associated with subduction
    • produce ash, gases, often explosive eruptions  
  • Hot Spots: 
    • build shield volcanoes (e.g. Hawai'i)

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