Depth and geoid anomalies over oceanic hotspot swells: A global survey

Journal Article · Mon Sep 10 04:00:00 EDT 1990 · Journal of Geophysical Research; (USA)

DOI:https://doi.org/10.1029/JB095iB10p15429· OSTI ID:6099916

Monnereau, M; Cazenave, A ^[1]

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1. Centre National d'Etudes Spatiales, Toulouse (France)

The broad depth and geoid anomalies associated with 23 hotspot swells in oceanic areas have been analyzed. Maximum height and geographical extent of the topographic swell, and of the geoid anomaly as well, have been measured for each hotspot. The results indicate a clear increase of the topographic swell height with age of the underlying lithosphere, from values in the range 300-500 m at young ages to values in the range 1,500-2,000 m at ages larger than 100 Ma. The geoid anomaly amplitude also increases with plate age from nearly zero close to mid-ocean ridges, to 6-8 m over old plates. On the other hand, the geographical extent of the swell does not show any clear relationship with plate age. The mean lateral extent of swells range from 1,000 to 1,500 km. Swells located close to spreading ridges show a significant non zero depth anomaly but are associated with negligible geoid signal. These results complete those of a previous study where the apparent compensation depth of oceanic hotspot swells was showed to increase linearly with the square root of plate age and coincide roughly with the base of the thermal lithosphere. This trend may either be interpreted in terms of lithospheric thinning or dynamical support. Besides both seem necessary to explain the observed bathymetry, in proportion evolving with aging of the lithosphere.

• OSTI ID: 6099916
• Journal Information: Journal of Geophysical Research; (USA), Journal Name: Journal of Geophysical Research; (USA) Vol. 95:B10; ISSN 0148-0227; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
AGE DEPENDENCE
BATHYMETRY
DEPTH
DIMENSIONS
EARTH CRUST
GEOGRAPHY
GEOLOGY
GEOMORPHOLOGY
GLOBAL ASPECTS
HEIGHT
OCEANIC CRUST
PLATE TECTONICS
SEA-FLOOR SPREADING
SWELLING
TECTONICS
TOPOGRAPHY
VOLCANISM