Accession Number : ADA325948

Title :   Mantle Plume-Midocean Ridge Interaction: Geophysical Observations and Mantle Dynamics.

Descriptive Note : Doctoral thesis,

Corporate Author : MASSACHUSETTS INST OF TECH CAMBRIDGE

Personal Author(s) : Ito, Garrett T.

PDF Url : ADA325948

Report Date : SEP 1996

Pagination or Media Count : 162

Abstract : We investigate the igneous and mantle dynamic processes of mantle plume midocean ridge interaction with geophysical observational and numerical modeling studies. Bathymetric and gravity anomalies along seafloor isochrons are examined at the Galapagos, Iceland, Azores, Tristan, and Easter plume ridge systems. Anomaly amplitudes decrease with increasing plume ridge distance whereas along-isochron widths decrease with increasing spreading rate. Three dimensional numerical models predict that along-axis plume width increases with plume volume flux but decreases with increasing spreading rate and plume ridge distance. Ridge migration is predicted to inhibit plume ridge interaction when ridges migrate toward plumes and enhance interaction when ridges migrate away from the plumes. The effects of decompression melting on plume density and viscosity do not appreciably affect the broad scale flow of the plume, but they do contribute significantly to predicted geophysical anomalies. Numerical models predict successfully the geophysical observations at the Iceland-Mid-Atlantic Ridge and Galapagos plume ridge systems. Predictions of geochemistry suggest that mixing between the plumes and ambient mantle most likely occurs below the asthenosphere. Models of the Iceland plume require substantial along-axis melt migration in order to explain a variety of geophysical and geochemical observations.

Descriptors :   *HOT SPOTS, *GEOPHYSICS, *GEOCHEMISTRY, *OCEAN RIDGES, *VOLCANISM, MATHEMATICAL MODELS, INTERACTIONS, FLUX(RATE), THESES, THREE DIMENSIONAL, BATHYMETRY, MIGRATION, FLOW, PLUMES, VISCOSITY, AZORES, EARTH MANTLE, GRAVITY ANOMALIES, ICELAND, IGNEOUS ROCK.

Subject Categories : Physical and Dynamic Oceanography
      Geology, Geochemistry and Mineralogy

Distribution Statement : APPROVED FOR PUBLIC RELEASE