Plate tectonics: controls on physiography of the sea floor.

Readings in the text, Sverdrup, Duxbury and Duxbury, 2004

pp. 52-95 (plate tectonics), 96-110 (bathymetry).

Physiography of the sea floor

I. Seafloor Morphology

A. The lay of the land

1) Crustal types:

Continental

Oceanic

2) Coastline not related to crust type- shelf break

B. Principle topographic features

1) Continental slope, shelf, break, rise

2) General basin profile

3) General Basin features: fracture zone, mountains, rifts

Plate tectonics.

I. What is Plate Tectonics?

Evolved from the idea of continental drift

Took modern methods and geophysical evidence to put it together.

The evidence: bathymetry, magnetics and earthquakes

II. Major features of the seafloor are all tectonic

A. Mid Ocean Ridges

ridges vs. rises

B. Fracture zones

C. Trenches and island (volcanic) arcs

D. Seamount and island chains

III. Continental Margins are tectonically controlled (and they are different from plate margins!!!)

A. Passive margins: low, flat, with lots of sediments

Active margins: short, steep, with coastal mountains

Summary and concepts to know

Plate tectonics: What is it and the mechanics of how it works.

Understand plate margins and their mechanics.

The features of plate tectonics in the ocean Ð how it controls seafloor features and continental margin types.