We discussed the square root of age dependence of oceanic lithospheric thickness, and how this controls the bathymetric profile across an ocean basin. As we have seen, this collapses to a simple equation for ocean depth:

where D is the ocean depth in m, D_o the depth at the spreading ridge in m, t is the age of the lithosphere in years, and k is the thermal diffusivity of the lithosphere. 

• Given this equation, and the plot of ocean depth vs. age for the first 80Ma for the North Pacific from Sclater’s work (Figure 3.2), calculate a value for the dimensionless constant, A. Assume a reasonable thermal diffusivity of 1mm²/s.

Figure 3.2

Transcribed Image Text:

D = Do +AV kt