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On the role of rheological memory for convection driven plate-reorganizations
  • Lukas Fuchs,
  • Thorsten Wolfgang Becker
Lukas Fuchs
Goethe University Frankfurt, Goethe University Frankfurt, Goethe University Frankfurt, Goethe University Frankfurt

Corresponding Author:lukas.fuchs84@gmail.com

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Thorsten Wolfgang Becker
University of Texas at Austin, University of Texas at Austin, University of Texas at Austin, University of Texas at Austin
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Abstract

Understanding the temporal variability of Earth’s tectonics is key to unraveling how mantle convection transports heat. The stability of plate motions depends on rheological “memory”, i.e., the persistence of weak zones. Here, we analyze the impact of such memory in global, oceanic-lithosphere only models of visco-plastic mantle convection. Self-consistently formed weak zones are reactivated in distinct modes, and convection selects pre-damaged zones preferentially for new plate boundaries. Any local stabilizing effects of weakening are overwhelmed statistically by the accumulation of rheological heterogeneity. Reactivation of damage zones increases the frequency of plate reorganizations and thus reduces the dominant period of heat loss fluctuations. In nature, the generation of sutures may thus counteract and possibly overcome the effects of reduced convective vigor throughout planetary cooling, with implications for the frequency of orogeny and convective transport throughout Wilson cycles.