Lateral Variation in Upper Mantle Viscosity: Role of Water
mantle, viscosity, Western United States, water
Digital Object Identifier (DOI)
Differences in the viscosity of the earth's upper mantle beneath the western US (∼1018–1019 Pa s) and global average values based on glacial isostatic adjustment and other data (∼1020–1021 Pa s) are generally ascribed to differences in temperature. We compile geochemical data on the water contents of western US lavas and mantle xenoliths, compare these data to water solubility in olivine, and calculate the corresponding effective viscosity of olivine, the major constituent of the upper mantle, using a power law creep rheological model. These data and calculations suggest that the low viscosities of the western US upper mantle reflect the combined effect of high water concentration and elevated temperature. The high water content of the western US upper mantle may reflect the long history of Farallon plate subduction, including flat slab subduction, which effectively advected water as far inland as the Colorado Plateau, hydrating and weakening the upper mantle.
Was this content written or created while at USF?
Citation / Publisher Attribution
Earth and Planetary Science Letters, v. 222, issue 2, p. 451-467
Scholar Commons Citation
Dixon, Jacqueline E.; Dixon, Timothy H.; Bell, D. R.; and Malservisi, R., "Lateral Variation in Upper Mantle Viscosity: Role of Water" (2004). School of Geosciences Faculty and Staff Publications. 460.