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Abstract Understanding the temporal variability of plate tectonics is key to unraveling how mantle convection transports heat, and one critical factor for the formation and evolution of plate boundaries is rheological “memory,” that is, the persistence of weak zones. Here, we analyze the impact of such damage memory in global, oceanic‐lithosphere‐only models of visco‐plastic mantle convection. Self‐consistently‐formed weak zones are found to be reactivated in distinct ways, and convection preferentially selects such damaged zones for new plate boundaries. Reactivation of damage zones increases the frequency of plate reorganizations, and hence reduces the dominant periods of surface heat loss. The inheritance of distributed lithospheric damage thus dominates global surface dynamics over any local boundary stabilizing effects of weakening. In nature, progressive generation of weak zones may thus counteract and perhaps overcome any effects of reduced convective vigor throughout planetary cooling, with implications for the frequency of orogeny and convective transport throughout Wilson cycles.
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Generation of Evolving Plate Boundaries and Toroidal Flow From Visco‐Plastic Damage‐Rheology Mantle Convection and Continents
Earth's style of planetary heat transport is characterized by plate tectonics which requires rock strength to be reduced plastically in order to break an otherwise stagnant lithospheric lid, and for rocks to have a memory of past deformation to account for strain localization and the hysteresis implied by geological sutures. Here, we explore ∼107Rayleigh number, visco‐plastic, 3‐D global mantle convection with damage. We show that oceanic lithosphere‐only models generate strong toroidal‐poloidal power ratios and features such as a mix of long‐wavelength tectonic motions and smaller‐scale, back‐arc tectonics driven by downwellings. Undulating divergent plate boundaries can evolve to form overlapping spreading centers and microplates, promoted and perhaps stabilized by the effects of damage with long memory. The inclusion of continental rafts enhances heat flux variability and toroidal flow, including net rotation of the lithosphere, to a level seen in plate reconstructions for the Cenozoic. Both the super‐continental cycle and local rheological descriptions affect heat transport and tectonic deformation across a range of scales, and we showcase both general tectonic dynamics and regionally applied continental breakup scenarios. Our work points toward avenues for renewed analysis of the typical, mean behavior as well as the evolution of fluctuations in geological and model plate boundary evolution scenarios.
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- PAR ID:
- 10495085
- Publisher / Repository:
- Wiley
- Date Published:
- Journal Name:
- Geochemistry, Geophysics, Geosystems
- Volume:
- 24
- Issue:
- 12
- ISSN:
- 1525-2027
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1029/2023GC011179
