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Sea Floor Spreading Theory

Initial Publication Date: December 21, 2006

Back Ground and Theory for Sea Floor Spreading

Cooling of the Oceanic Lithosphere and Ocean Floor Topography

full on-line paper by David Sandwell ( This site may be offline. )

This lecture is the development of the lithospheric cooling problem......

Sandwell outlines the derivation of calculating the ocean floor depth below the ridge using thermodynamics and structural arguments. We provide a very brief outline here and present the relevant equations in the form used by us for our Excel Sea Floor Spreading Activities (Activity I & Activity II).

sea Floor model eqn from Sandwell
Equation 37. from Sandwell except that we use distance over speed (x/u) in place of t.

Sketch of ocean lithosphere and mantle for sea floor spreading model

Sketch of Model.

Model parameters

parameters for Sea Floor Spreading Model
Sea Floor Spreading Eqn. for C

Using these constants we express the depth of the ocean floor below the oceans surface as

d=-do-.11*sqrt(10 x/u)

where K = 1x10-6m2/s = 31.5 km2/Myr , p = 3.14, X is the horizontal distance from the ridge measured in km and u is the sea floor spreading rate in km/Myr. Where we have assumed that the ridge is a depth, do, below the oceans surface. This gives use three adjustable parameters to use for our Excel assignments in Activity I & Activity II.


Reference

A complete derivation of equation 37 is also contained in:

Geodynamics Second Eddition by Donald Turcotte and Gerlad Schubert, Cambridge University Press, 2002.