Hotspots and mantle plumes: Some Phenomenology

Journal Article · Thu May 10 04:00:00 EDT 1990 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/JB095iB05p06715· OSTI ID:5009832

Sleep, N H ^[1]

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1. Stanford Univ., CA (United States)

The available data, mainly topography, geoid, and heat flow, describing hotspots worldwide are examined to constrain the mechanisms for swell uplift and to obtain fluxes and excess temperatures of mantle plumes. Swell uplift is caused mainly by excess temperatures that move with the lithosphere plate and to a lesser extent hot asthenosphere near the hotspot. The volume, heat, and buoyancy fluxes of hotspots are computed from the cross-sectional areas of swells, the shapes of noses of swells, and, for on ridge hotspots, the amount of ascending material needed to supply the length of ridge axis which has abnormally high elevation and thick crust. The buoyancy fluxes range over a factor of 20 with Hawaii, 8.7 Mg/s, the largest. The buoyancy flux for Iceland is 1.4 Mg/s which is similar to the flux of Cape Verde. The excess temperature of both on-ridge and off-ridge hotspots is around the 200 C value inferred from petrology but is not tightly constrained by geophysical considerations. This observation, the similarity of the fluxes of on-ridge and off-ridge plumes, and the tendency for hotspots to cross the ridge indicate that similar plumes are likely to cause both types of hotspots. The buoyancy fluxes of 37 hotspots are estimated; the global buoyancy flux is 50 Mg/s, which is equivalent to a globally averaged surface heat flow of 4 mW/m{sup 2} from core sources and would cool the core at a rate of 50 C/b.y.. Based on a thermal model and the assumption that the likelihood of subduction is independent of age, most of the heat from hotspots is implaced in the lower lithosphere and later subducted.

• OSTI ID: 5009832
• Journal Information: Journal of Geophysical Research; (United States), Journal Name: Journal of Geophysical Research; (United States) Vol. 95:B5; ISSN 0148-0227; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
AGE ESTIMATION
CAPE VERDE ISLANDS
DEVELOPED COUNTRIES
DEVELOPING COUNTRIES
EARTH CORE
EARTH MANTLE
EUROPE
FEDERAL REGION IX
FLUID MECHANICS
GEOLOGY
HAWAII
HEAT FLOW
HOT SPOTS
ICELAND
ISLANDS
MECHANICS
NORTH AMERICA
PETROLOGY
PLATE TECTONICS
RESERVOIR TEMPERATURE
ROCK MECHANICS
SUBDUCTION ZONES
TECTONICS
THERMODYNAMICS
TOPOGRAPHY
USA