PLATE TECTONICS AND CLIMATE

Objectives

1.     Define plate tectonics and describe the mechanics which drive it, including the dynamics of plate margins

2.         Understand the features of oceanic plate tectonics, and how they control seafloor features and continental margin types

3.         Understand how continents control climate through their effects on ocean currents and heat transport on Earth

Physiography of the sea floor

I. Sea floor morphology

A.    The lay of the land

1)    Crustal types:

       Continental

       Oceanic

2)    Coastline not related to crust type- shelf break.

B.    Principal 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?

     A. Evolved from the idea of continental drift

     B. 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.   Sea mount 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

B.    Active margins: short, steep, with coastal mountains

IV.  Tectonic control on climate

A.    Plate locations control currents

B.    Continental location shifts currents from a circum-equatorial to a circum-polar current

C.    Over ~65 million years the earth shifts from a greenhouse climate to an icehouse climate

D.   Gateways are important