Mantle flow, melting, and dehydration of the Iceland mantle plume
Document Type
Article
Date of Original Version
1-15-1999
Abstract
Recent studies have shown that the extraction of water from the mantle due to partial melting beneath mid-ocean ridges may increase the viscosity of the residuum by 2-3 orders of magnitude. We examine this rheological effect on mantle flow and melting of a ridge-centered mantle plume using three-dimensional numerical models. Results indicate that the viscosity increase associated with dehydration prevents buoyancy forces from contributing significantly to plume upwelling above the dry solidus. Consequently, upwelling in the primary melting zone is driven passively by plate spreading and melt production rates are substantially lower than predicted by models that do not include the rheological effect of dehydration. Predictions of along-axis crustal thickness, bathymetric, and gravity variations are shown to be consistent with observations at Iceland and along the Mid-Atlantic Ridge. Furthermore, these predictions result from a model of a plume with relatively high excess temperature (180°C) and narrow radius (100 km) - properties that are consistent with estimates previously inferred from geochemical and seismological observations. Calculations of incompatible trace-element concentrations suggest that observed along-axis geochemical anomalies primarily reflect incompatible element heterogeneity of the plume source.
Publication Title, e.g., Journal
Earth and Planetary Science Letters
Volume
165
Issue
1
Citation/Publisher Attribution
Ito, Garrett, Yang Shen, Greg Hirth, and Cecily J. Wolfe. "Mantle flow, melting, and dehydration of the Iceland mantle plume." Earth and Planetary Science Letters 165, 1 (1999). doi: 10.1016/S0012-821X(98)00216-7.