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The inability of the model to predict a correct sea floor profile, as Joe has pointed out is another example of conflicting data.
However, it closely matches the density profiles given by seismic models, and an argument in its favor is that there is presently no ocean floor on the earth that predates the deposition of the fossiliferous strata. (As in the model it would have subducted into the mantle).
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would call dropping the mantle viscosity by a billion fold more than tweaking. Using totally unrealistic parameters is not tweaking. GIGO. But don't you claim that there are no good mainstream tectonic simulators? I don't know exactly how good Baumgardner's mainstream model is compared to others but it is obviously far better than his boiling flood model.
Not quite a billion, but rather a hundred million. However, the parameters are not unrealistic-
quote:
"yields more than eight orders of magnitude reduction in effective viscosity relative to a condition of zero strain rate. Indeed maximum strain rates implied by the calculated velocities are on the order of 10-4 s-1 --precisely in the range for which laboratory measurements have been made"--Baumgardner
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"How do the parameters used in these calculations compare with those estimated for the earth? The values used for g, g, k, H, rr, cv, Tr, and a in eq. (1)-(5) are all reasonable to within +/-30% for the simplified reference state that is employed. The values used for the Clapeyron slopes for the phase transitions are two to three times too small and so the effects of the phase changes are underrepresented. The most important parameters are the reference viscosity and the threshold strain rate for power-law creep. The reference viscosity leads to velocities prior to runaway that are in accord with current observed plate velocities of a few centimeters per year. The threshold strain rates used are within the power-law creep region for olivine as given by Kirby (Fig. 1). A large uncertainty is the extrapolation of the creep behavior of olivine to the minerals of the lower mantle for which there is essentially no experimental data. The issue is not whether power-law creep occurs in these minerals but what the stress range is in which it occurs. It is likely the threshold strain rate is not many orders of magnitude different from olivine. These calculations therefore seem relevant to the earth as we observe it today."--Baumgardner
[This message has been edited by blitz77, 08-19-2002]
[This message has been edited by blitz77, 08-19-2002]
[This message has been edited by blitz77, 08-19-2002]
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