Effects of Hydrothermal Cooling and Magma Injection on Mid‐Ocean Ridge Temperature Structure, Deformation, and Axial Morphology

摘要: Fault development at mid-ocean ridge spreading centers is strongly dependent on the thermal state of axial lithosphere. Thermal conditions a axis are combined function rate, mantle temperature, magma injection, and hydrothermal circulation. In this study, we test sensitivity fault in slow-spreading environments to efficiency cooling depth extent injection near axis. A 3-D finite difference scheme first used calculate temperature structure, deformation then modeled 2-D vertical sections lithosphere using visco-plastic element model. Strain-rate softening brittle regime simulate rate-dependence frictional strength observed laboratory studies. This formulation results formation localized zones high strain rate (analogous faults) that develop response rheology boundary not imposed priori. Comparing our numerical experiments with faulting center ends several segments along Mid-Atlantic Ridge, find temperatures segment end must be warmer than predicted by previous models. These can explained either inefficient shallow crust or heating upper through magmatic accretion below Moho. Because geophysical geochemical evidence support efficient young oceanic lithosphere, favor model which heat supplied beneath crystallization rising asthenospheric melts episodic lateral dike propagation from center.