Rock in the Earth's mantle melts as it upwells toward the surface, as can be seen beneath mid-ocean ridge spreading centers. This buoyant melt rises through the mantle to the surface, where it solidifies and becomes part of the Earth's crust. However, the pathways through which mantle melt migrates have not been well understood. It had been suggested that channels through highly porous dunite rock provided pathways for mantle melt, but the depth and other features of these channels have not been known.
To investigate how dunite channels would form and how melt would flow through them in an upwelling mantle, Liang et al. conduct numerical simulations. They find that interconnected dunite channels form the shallow part of the porous channels through which melt passes. However, deeper in the mantle, melt travels through channels composed of the rocks harzburgite and lherzolite.
In addition, the simulation shows that primary channels deeper in the mantle can lead to the formation of shallower secondary channels created by reactions between melt and rock during melt migration. These results could help geologists interpret field measurements and improve models for mantle melt migration, shedding light on mantle dynamics and crust formation.
Authors of the study include: Yan Liang, E. Marc Parmentier: Department of Geological Sciences, Brown University, Providence, Rhode Island, USA; Alan Schiemenz: Department of Geological Sciences, Brown University, Providence, Rhode Island, USA and Division of Applied Mathematics, Brown University, Providence, Rhode Island, USA; Marc A. Hesse: Department of Geological Sciences, Brown University, Providence, Rhode Island, USA, now at Department of Geological Sciences, University of Texas at Austin, Austin, Texas, USA; Jan S. Hesthaven: Division of Applied Mathematics, Brown University, Providence, Rhode Island, USA.
- Yan Liang, Alan Schiemenz, Marc A. Hesse, E. Marc Parmentier, Jan S. Hesthaven. High-porosity channels for melt migration in the mantle: Top is the dunite and bottom is the harzburgite and lherzolite. Geophysical Research Letters, 2010; 37 (15): L15306 DOI: 10.1029/2010GL044162
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