True and Apparent Polar Wander From Sluggish to Active Lid Tectonics

Le résumé fourni par la source

Abstract It has been proposed that to satisfy a wide range of geological observations, early Earth mantle convection operated in “sluggish‐lid” tectonics before transitioning to modern‐day, “active‐lid” tectonics. The former is the result of a weaker asthenosphere relative to the latter and manifests itself in a partially decoupled plate‐mantle system. This transition is required to produce reasonable apparent polar wander (APW) plate velocities over Earth history. Since these tectonic regimes are dictated by the thermo‐mechanical structure of the mantle, they should also influence true polar wander (TPW). Here, we explore the relative importance of TPW within a mantle that transitions from sluggish‐to active‐lid tectonics to provide some context on how to interpret paleomagnetic observations over Earth history. We find that TPW rates are faster when Earth's mantle operates in sluggish‐lid tectonics than active‐lid, contrary to previous results that appear to only be appropriate for active‐lid TPW. We also find that if subduction initiated during sluggish‐lid tectonics, this could also lead to high, intermittent rates of TPW.

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