Seafloor spreading on Short And Long Time scales

Seafloor spreading is the process that single-handedly shapes 2/3 of our planet, modulates the dynamics of deep ocean currents, controls the composition of seawater, and supports unique ecosystems that thrive in extreme environments.

Discovered in the 1960s, it is now explained as the slow and steady divergence of 2 tectonic plates accommodated by magma emplacement and faulting at a mid-ocean ridge axis.

In the current paradigm, the texture of the seafloor is primarily determined by the magmatically-accommodated fraction (M) of plate separation at the ridge axis.

However, we do not know what sets the M fraction in the first place, and why it is subject to spatiotemporal fluctuations that can cause drastic shifts in seafloor spreading regimes.

SeaSALT tackles this issue by rethinking seafloor spreading as a succession of discrete magmatic and tectonic events which, by inhibiting or triggering one another, self-consistently distribute magmatic and tectonic strain.

To test this hypothesis, we will design brand-new simulations of seismo-volcanic cycles in which dike intrusions, earthquakes, or aseismic slip transients may occur in response to far-field extension and pressurization of a shallow magma reservoir.

Each component of the model will be constrained by groundbreaking observations of seafloor spreading events and inter-event stress build-up at 3 target sites.

This includes the most ambitious seafloor seismo-geodesy experiment to date across a ridge axis, and the development of a novel hydrothermal geodesy method that constrains sub-seafloor stress changes via the perturbations they impart on black smoker temperatures.

The success of our new framework will be indexed on its ability to spontaneously generate the types of events documented at each site, while accounting for the M fraction and its multiscale variability, as recorded in high-resolution bathymetry. It will also help forecast hazards to rift populations and key submarine infrastructure.