Breaking Earth's shell into a global plate network.

Area of Science:

• Solid Earth geophysics
• Planetary science
• Geodynamics

Background:

• The initiation of Earth's plate tectonics is poorly understood.
• Previous models suggest a single-plate stage preceded multi-plate tectonics.
• Existing models often use continuum mechanics approximations.

Purpose of the Study:

• To investigate the self-organized fracture mechanism for early lithospheric breakup.
• To determine the factors controlling early plate scale and fracture spacing.
• To propose a viable mechanism for the onset of plate tectonics.

Main Methods:

• Utilized 3D spherical shell models to simulate lithospheric behavior.
• Employed a fracture mechanics approach, distinct from continuum approximations.
• Analyzed the role of horizontal extension and thermal expansion.

Main Results:

• Demonstrated globe-spanning rifting via a self-organized fracture mechanism.
• Identified lithospheric thickness and rheology as key controls on fracture spacing.
• Showed that geometrically regular, polygonal tessellations minimize total crack length.

Conclusions:

• Early lithospheric warming can drive failure and fracture propagation.
• This mechanism provides conditions necessary for the onset of multi-plate tectonics.
• The findings offer a new perspective on early Earth geodynamics.