Chapter 4 wrapup

Extra Credit Option:

Attend the Public Lecture by Prof. Antonio
Lazcano on Tuesday (tomorrow) evening,
Feb 11 at 7:30 PM in Gammage Auditorium
here on campus. Write up a short summary
2-3 paragraphs for the talk, highlighting
the aspects you found most interesting.
Bring your write-up to class on Wednesday.
Be sure to write your name and ASU ID at
the top of the page.


Today’s Lecture:

 Plate margins and associated geological
pheneomena.
- Intraplate hot-spots.
- Divergent plate margins in continental settings
(origin of new ocean basins).
- Convergent margins
- Continental margin settings.
- Transform margins (ridge transforms and onland transforms.
 Brief Review
 Quiz
 Next time: Interlude A and Chapter 5!


PLATE
TECTONICS

Location of Earth’s Hot-spots


PLATE
TECTONICS

Yellowstone Hot Spot


PLATE
TECTONICS

Yellowstone Hot Spot


PLATE
TECTONICS

Types of Plate Boundaries

3 types
● divergent boundaries

● convergent boundaries

● transform fault boundaries


PLATE
TECTONICS

Continental Rifting: East Africa

Red Sea (looking southeast)


PLATE
TECTONICS

Opening of the Red Sea


PLATE
TECTONICS

Opening of the Red Sea


PLATE
TECTONICS

Formation of Triple Junctions


ocean-continent

ocean-ocean

continent-continent

3 Types of Convergent Plate Margins


Types of Continental Margins

“Active”
 Found along convergent
plate margins:
 Primarily around the
Pacific rim.
 Characterized by active
narrow continental
shelves and active
mountain building
processes (earthquakes &
volcanic activity).
 Accretionary wedges of
sediment which are
scraped off the top of a
subducting slab.


Types of Continental Margins

“Passive”
 Found within plate
interiors:
 Continental margin not
= a plate margin
Examples are

continental margins
around Atlantic.
 Broad continental
shelves consist of thick
wedges of sediment
deposited along margins
 Few earthquakes or
volcanic eruptions.


Comparison of Active and Passive
Continental Margins


PLATE
TECTONICS

Transform Plate Margins

● Transform fault boundaries
Strike-slip faults where plates slide past each other:
No production/destruction
of material
Most connect mid-ocean ridge segments
Others are “on-land”
transforms like the
San Andreas Fault.


PLATE

TECTONICS

Transform Plate Margins


On-Land Transform Faults

San Francisco Peninsula
and San Andreas Fault


In-class exercise. Name:______________________
GLG 101 Prof. Far m er ASU ID:________________
Compare the continental margin of the west coast of S. America
with the east coast of N. America.

1) South Am.
2) North Am.

Questions:
a) Active or passive continental margin?
b) Draw a cross-section (a side view)
of each area, labeling the most
important features.