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Magma production beneath mid-ocean ridges: Using numerical models to evaluate the solidus
  • Francesca Burkett,
  • James Conder
Francesca Burkett
Southern Illinois University

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James Conder
Southern Illinois University Carbondale
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Over 95% of volcanism on Earth occurs at mid-ocean ridges (MORs) where tectonic plates diverge. How melt is produced depends on the mineral composition and water content. However, it has proven challenging to understand how melting changes when one or more minerals have completely melted. This project examines differences on MOR melting that come with different assumptions in solidus changes with exhaustion of one of the component minerals, clinopyroxene (cpx). To do this, we constructed 2D numerical models of temperature, mantle flow, and melt production at MORs. We ran several models with different amounts of temperature shift in the solidus with loss of cpx. Using zero shift as a baseline, melting starts around 80km depth and peaks at 35km, exhausting cpx, lowering melt output. A second smaller melting region develops more shallowly where there is no cpx. Additional trials in changing the shift in solidus with loss of cpx were done with varying amounts of mantle hydration. For all trials, total melt decreases with larger shifts in solidus. The shallower melting disappears as greater shifts are made. Increasing hydration allows melting to start at deeper depths, but has little effect on the total amount of melt production.