Winter 2001

Problem Set #1

Due Wednesday, January 17, 2001

- As a simple model for isostatic equilibrium of the earth, with compensation
within the mantle, consider a
continental block of thickness T in relationship to an ocean of depth 4
km and an oceanic crust 6 km thick.
Derive an expression for the elevation of the continent above sea level
as a function of T. For densities assume continent 2700 kg
m
^{-3}, ocean 1000 kg m^{-3}, oceanic crust 3000 kg m^{-3}, and mantle 3300 kg m^{-3}. What is the minimum thicness of the continental block for it to stand above sea level? - If the average spreading rate of the mid-ocean ridge system were to increase by 50%, estimate the size of the change in sea level that would result. Assume a symmetric ocean basin (ridge in center, subduction at both sides) of width 12000 km. Comment on any other assumptions that you make and assess their validity.
- Suppose that at the end of the last glacial period, the temperature
of the deep northern Atlantic Ocean abruptly increased 1°C. introducing a
thermal perturbation in the underlying sediments. How much
time would need to pass before a reliable conductive heat flow
measurement could again be made? What criteria have you adopted for the
term
*reliable*? (Hint: It is useful to work at the limit of no pre-existing heat flow.) - Consider the binary system Di-An. Draw plots of the relationships of
the composition of the liquid, the composition of the residual solid and
the temperature as a function of the fraction of liquid for a closed,
equilibrium system of bulk composition An
_{25}. Phase Diagram for System Di-An.

Oceanography 540 Pages Pages Maintained by Russ McDuff (mcduff@ocean.washington.edu) Copyright (©) 1994-2001 Russell E. McDuff and G. Ross Heath; Copyright Notice Content Last Modified 1/5/2001 | Page Last Built 1/5/2001 |