Sensitivity of geomagnetic reversal rate on core evolution from numerical dynamos
Abstract
The paleomagnetic record indicates the geodynamo has evolved from frequently reversing to non-reversing (superchron) magnetic states several times over the Phanerozoic. Previous theoretical studies demonstrated a positive correlation between magnetic reversal rate and core-mantle boundary heat flux. However, attempts to identify such a correlation between reversal rates and proxies for internal cooling rate, such as plume events, superchron cycles, and subduction rates, have been inconclusive. Here we revisit the magnetic reversal occurrence rate in numerical dynamos at low Ekman numbers (faster rotation) and high magnetic Prandtl numbers (ratio of viscous and magnetic diffusivities). We focus on how the correlation between reversal rate and convective power depends on the core evolution rate and on other factors, such as Ek, Pm, and thermal boundary conditions. We apply our results to the seafloor reversal record in an attempt to infer the energetic evolution of the lower mantle and core over that period.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2017
- Bibcode:
- 2017AGUFMDI33B0410D
- Keywords:
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- 1507 Core processes;
- GEOMAGNETISM AND PALEOMAGNETISM;
- 1510 Dynamo: theories and simulations;
- GEOMAGNETISM AND PALEOMAGNETISM;
- 3924 High-pressure behavior;
- MINERAL PHYSICS;
- 7207 Core;
- SEISMOLOGY