Subduction Zones
Geosyncline
What We Actually See
What Does This Look Like?
Andes – True Scale
Continent-Continent Collision
Continent-Terrane Collision
Where Does Ocean Crust Go?
Hugo Benioff, 1954
1. How we know plate tectonics happens
Benioff’s Interpretation
1. How we know plate tectonics happens
Benioff’s Interpretation Updated
1. How we know plate tectonics happens
How Plates Move
A Subduction Zone
Subduction and Metamorphism
Why Mountains are High
Where the Plates Meet
Terrane Accretion
Terranes in
Western North
America
Subduction Zone Rocks
Steinmann Trinity (1905)
• Serpentinite
• Pillow Basalt
• Radiolarian Cherts
• Characteristic of ophiolite settings
• Other Distinctive Rocks
– Graywacke and Flysch
– Blueschist
Bedded Chert
Serpentinite
Serpentinite
Magnesite Mines in Serpentinite
Pillow Lava
Pillow Lava
Pillow Lava
Blueschist
Graywacke
Flysch
Melange
Melange
Eclogite
Molasse,
Switzerland
Molasse and the High Alps
Wisconsin 2 Billion Years Ago
1900 MY Penokean Orogeny
Before the Penokean Orogeny
First Collision
Second Phase
Marshfield Terrane Collides
Assembling
North
America
Assembling
North
America
1700 MY Granite and Rhyolite
Mazatzal
Orogeny
Cactus Rock
Baraboo Interval Quartzites
“Baraboo Interval”
Yavapai
Orogeny
Baraboo Quartzite
Mazatzal-Yavapai Events
1450 MY Wolf River Batholith
Wolf River Batholith
1100 MY Mid-Continent Rift
The
Grenville
Orogeny
Begins
The
Grenville
Orogeny
A Subduction Zone
How Arcs Grow
Exotic Terranes