Abstract
We outline a linearized rotational stability theory for predicting the time dependence of true polar wander (TPW) on a Maxwell viscoelastic body in response to mantle convective loading. The new theory is based on recent advances in ice age rotation theory. A comparison between predictions based on the new theory and analytic expressions for equilibrium (infinite-time) TPW on planetary models with elastic lithospheres demonstrates that the linearized theory can, in the case of loading at mid-latitudes, predict TPW of over 20° to better than 5 per cent accuracy. We present predictions of TPW for loading with periodic and net ramp-up time histories. Moreover, we compare the time dependence of TPW under assumptions consistent with the canonical equilibrium stability theory adopted in most previous analyses of convection-induced TPW, and a stability theory that includes two effects that have not been considered in previous geophysical analyses: (1) the so-called 'remnant rotational bulge' associated with the imperfect reorientation of the rotational bulge due to the presence of an elastic lithosphere; and (2) a stable (over the timescale of the forcing) excess ellipticity. As a first application of the new theory, we consider recent inferences of rapid (order 1 Myr) TPW motion of amplitude 10°-20° during the Late Cretaceous. We conclude that excursions of this amplitude and timescale are physically implausible.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 1319-1333 |
| Number of pages | 15 |
| Journal | Geophysical Journal International |
| Volume | 187 |
| Issue number | 3 |
| DOIs | |
| State | Published - Dec 2011 |
| Externally published | Yes |
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Keywords
- Earth rotation variations
- Palaeomagnetic secular variation
- Rheology: crust and lithosphere
ASJC Scopus subject areas
- Geochemistry and Petrology
- Geophysics
Cite this
The rotational stability of a convecting earth : Assessing inferences of rapid TPW in the late cretaceous. / Chan, N. H.; Mitrovica, J. X.; Matsuyama, Isamu M; Creveling, J. R.; Stanley, S.
In: Geophysical Journal International, Vol. 187, No. 3, 12.2011, p. 1319-1333.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - The rotational stability of a convecting earth
T2 - Assessing inferences of rapid TPW in the late cretaceous
AU - Chan, N. H.
AU - Mitrovica, J. X.
AU - Matsuyama, Isamu M
AU - Creveling, J. R.
AU - Stanley, S.
PY - 2011/12
Y1 - 2011/12
N2 - We outline a linearized rotational stability theory for predicting the time dependence of true polar wander (TPW) on a Maxwell viscoelastic body in response to mantle convective loading. The new theory is based on recent advances in ice age rotation theory. A comparison between predictions based on the new theory and analytic expressions for equilibrium (infinite-time) TPW on planetary models with elastic lithospheres demonstrates that the linearized theory can, in the case of loading at mid-latitudes, predict TPW of over 20° to better than 5 per cent accuracy. We present predictions of TPW for loading with periodic and net ramp-up time histories. Moreover, we compare the time dependence of TPW under assumptions consistent with the canonical equilibrium stability theory adopted in most previous analyses of convection-induced TPW, and a stability theory that includes two effects that have not been considered in previous geophysical analyses: (1) the so-called 'remnant rotational bulge' associated with the imperfect reorientation of the rotational bulge due to the presence of an elastic lithosphere; and (2) a stable (over the timescale of the forcing) excess ellipticity. As a first application of the new theory, we consider recent inferences of rapid (order 1 Myr) TPW motion of amplitude 10°-20° during the Late Cretaceous. We conclude that excursions of this amplitude and timescale are physically implausible.
AB - We outline a linearized rotational stability theory for predicting the time dependence of true polar wander (TPW) on a Maxwell viscoelastic body in response to mantle convective loading. The new theory is based on recent advances in ice age rotation theory. A comparison between predictions based on the new theory and analytic expressions for equilibrium (infinite-time) TPW on planetary models with elastic lithospheres demonstrates that the linearized theory can, in the case of loading at mid-latitudes, predict TPW of over 20° to better than 5 per cent accuracy. We present predictions of TPW for loading with periodic and net ramp-up time histories. Moreover, we compare the time dependence of TPW under assumptions consistent with the canonical equilibrium stability theory adopted in most previous analyses of convection-induced TPW, and a stability theory that includes two effects that have not been considered in previous geophysical analyses: (1) the so-called 'remnant rotational bulge' associated with the imperfect reorientation of the rotational bulge due to the presence of an elastic lithosphere; and (2) a stable (over the timescale of the forcing) excess ellipticity. As a first application of the new theory, we consider recent inferences of rapid (order 1 Myr) TPW motion of amplitude 10°-20° during the Late Cretaceous. We conclude that excursions of this amplitude and timescale are physically implausible.
KW - Earth rotation variations
KW - Palaeomagnetic secular variation
KW - Rheology: crust and lithosphere
UR - http://www.scopus.com/inward/record.url?scp=81555213487&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=81555213487&partnerID=8YFLogxK
U2 - 10.1111/j.1365-246X.2011.05245.x
DO - 10.1111/j.1365-246X.2011.05245.x
M3 - Article
VL - 187
SP - 1319
EP - 1333
JO - Geophysical Journal International
JF - Geophysical Journal International
SN - 0956-540X
IS - 3
ER -