A thermomechanical numerical model for crustal accretion of medium to fast spreading mid-ocean ridges

Philippe Machetel (1) , C. J. Garrido (2)

1 Géosciences Montpellier
2 IACT - Instituto Andaluz de Ciencias de la Tierra

We propose a new thermomechanical numerical model of mid-ocean ridge accretion aimed at investigating asymmetric spreading rates, diverse configurations of lens and sill magma injections, crystallization and depth, and on- and off-axis patterns of hydrothermal cooling. The numerical algorithm iteratively resolves temperature and motion equations until it reaches a stationary solution. The motion equation was written in a vorticity-stream function formalism, with boundary and internal conditions applied to the stream function to impose the style of magma injection. Unlike in previous models, our model does not assume an a priori shape for the temperature field, which is initiated by an initial half-space cooling according to the left and right spreading rates. Complex patterns of hydrothermal cooling are simulated by enhanced thermal diffusivity. The model succeeds in describing the dynamic and thermal effects of spreading rates, the style of magma intrusion, and the hydrothermal cooling. Accurate descriptions of these are essential to study the cooling histories of crustal rocks and geophysical observables.

Mots clés: mid-oceanic ridge; numerical models; asymmetric ridge; hydrothermal cooling; magma chamber; cooling history

Domaines: Géophysique [physics.geo-ph]; Géophysique [physics.geo-ph]; Milieux et Changements globaux

Philippe Machetel, C. J. Garrido. A thermomechanical numerical model for crustal accretion of medium to fast spreading mid-ocean ridges. Geochemistry, Geophysics, Geosystems, 2009, 10, pp.Q03008. ⟨10.1029/2008GC002270⟩. ⟨hal-00413118⟩