Chapter 13: Divergent boundaries, origin
and evolution of the ocean floor
- Use of sonar and other remote sensing messages to map the
topography of the ocean floor
- ocean floors
- passive continental margins: continental shelf, slope, and
rise; ancient normal faults beneath sediment cover at passive margins
- trenches and subduction zones, volcanic island arcs, and
tectonically
active continental margins with accretionary wedges
- submarine canyons
- abyssal plains
- mid-ocean ridges and transform fault/fracture zones; note
symmetrical
pattern of topography on opposite sides of ridges
- spreading rates
- seamounts and guyots, coral reefs and atolls (not discussed in
class)
- structure of oceanic crust (see p.397); ophiolites and their
significance
- differences in elevation and slope of the mid-ocean ridge based
on temperature, speed of sea-floor spreading and rate of cooling and
sinking of oceanic crust as it spreads away from the ridge
- hydrothermal vents and their significance
- continental rifting and formation of new ocean basins: the
example of east Africa, Arabia and the Red Sea
- the supercontinent cycle (sometimes called the Wilson cycle):
before and after Pangaea; and the possible role of mantle plumes or hot
spots in continental rifting
- destruction of oceanic lithosphere at subduction zones
- how and why subduction occurs
- what happens when a mid-ocean ridge goes down a trench? The
example of the Farallon plate, the North American plate, and the
evolution of the west coast of the U.S.