Hotspot swells revisited

• Published in: Physics of the Earth and Planetary Interiors
• Main Authors: King, Scott D., Adam, Claudia
• Other Authors: Geosciences
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier 2014
• Subjects: Physical Sciences; Geochemistry & Geophysics; Hotspot swells; Depth anomalies; Buoyancy flux; Heat flow; SOUTH-PACIFIC SUPERSWELL; MANTLE PLUMES; TRANSITION ZONE; HEAT-FLOW; OCEANIC LITHOSPHERE; STRUCTURE BENEATH; PLATE VELOCITIES; ORIGIN; MODELS; SUBSIDENCE; 0201 Astronomical and Space Sciences; 0402 Geochemistry; 0404 Geophysics; Antarctic; Pacific; Antarc*
• Online Access: http://hdl.handle.net/10919/103026; https://doi.org/10.1016/j.pepi.2014.07.006

The first attempts to quantify the width and height of hotspot swells were made more than 30. years ago. Since that time, topography, ocean-floor age, and sediment thickness datasets have improved considerably. Swell heights and widths have been used to estimate the heat flow from the core-mantle boundary, constrain numerical models of plumes, and as an indicator of the origin of hotspots. In this paper, we repeat the analysis of swell geometry and buoyancy flux for 54. hotspots, including the 37 considered by Sleep (1990) and the 49 considered by Courtillot et al. (2003), using the latest and most accurate data. We are able to calculate swell geometry for a number of hotspots that Sleep was only able to estimate by comparison with other swells. We find that in spite of the increased resolution in global bathymetry models there is significant uncertainty in our calculation of buoyancy fluxes due to differences in our measurement of the swells' width and height, the integration method (volume integration or cross-sectional area), and the variations of the plate velocities between HS2-Nuvel1a (Gripp and Gordon, 1990) and HS3-Nuvel1a (Gripp and Gordon, 2002). We also note that the buoyancy flux for Pacific hotspots is in general larger than for Eurasian, North American, African and Antarctic hotspots. Considering that buoyancy flux is linearly related to plate velocity, we speculate that either the calculation of buoyancy flux using plate velocity over-estimates the actual vertical flow of material from the deep mantle or that convection in the Pacific hemisphere is more vigorous than the Atlantic hemisphere. 2014 Elsevier B.V. Published (Publication status)