Bridging Theory and Nature: Numerical Simulations to Understand Mid-Ocean Ridge Formation, Transform Faults and Microplates
Authors: Hafermaas Daniel , Koehn Daniel 
Published: March 2024

In the quest to deepen our understanding of mid-ocean ridge dynamics, this study presents coupled numerical simulations focused on the intricate processes of ridge formation and propagation leading to micro-plate creation, their rotation and the formation of transform faults. Our numerical approach to the problem is based on a 2.5D approximation with a fracturing brittle and a ductile viscous layer coupled to a temperature field. The growth of new oceanic material is modelled by the introduction of new hot particles in opening fractures and the plates cool by temperature diffusion. Thermo-mechanical coupling is induced by a reduction of breaking strength, elastic constants and viscosity of the solid as a function of temperature leading to weakening of material whereas a healing function that is reconnecting broken bonds leads to hardening. Initially we are inserting seeds for offset ridges so that overlaps and potential transform faults are predefined, however, we also observe the first self-developing transform faults in the system. The model is not as complex as some existing full 3D models, however it offers to study the complexity of the brittle processes and the growth of ridges in detail.Central to our investigation is the comprehensive simulation of mid-ocean ridge systems under varying spreading rates and the creation of micro-plates versus stable transform faults as well as the comparison to natural settings. Fast spreading rates lead to hot ridges in nature and in the model, because hot material is added faster than the heat can diffuse, whereas slow ridges remain relatively cool. Higher temperature is thought to lead to faster healing in our model, which counteracts the weakening induced by higher temperature. We modelled the formation and evolution of microplates and transform faults, uncovering the critical role of healing and weakening rates in shaping these features. Faster healing leads to micro-plate formation whereas more weakening, especially the reduction of the breaking strength, induces stable transform faults. The interplay between ridges is very dynamic with a continuous process of microplate rotation versus micro-plate splitting, their integration in the mid-ocean ridge and their destruction when transform faults form. The important parameters in the simulations that prefer micro-plate formation are higher breaking strength, fast healing, low viscosity and larger lateral distance between opening ridges.The integrated analysis from our numerical simulation enriches the existing understanding of mid-ocean ridge dynamics. It highlights the nuanced interplay between spreading rates, lithospheric stress, and thermo-mechanical coupling in shaping the oceanic crust. The findings from our study, particularly the spinning of microplates and the formation of transform faults, provide a new dimension to our comprehension of these geological features.This research contributes significantly to marine geology, offering a framework for future explorations and a benchmark for comparison with natural ridge systems. The detailed insights gained from our simulation pave the way for more informed interpretations of mid-ocean ridge processes and underscore the potential of numerical modelling in advancing our knowledge of Earth's dynamic systems.