Evolution of mid-plate hotspot swells, mantle plumes, and Hawaiian basalts

Thesis/Dissertation · Sun Jan 01 04:00:00 EST 1989

OSTI ID:6403659

Liu, Mian

Studies of the evolution of hotspot swells, mantle plumes, and Hawaiian basalts are presented in three parts in this dissertation. In part 1, the evolution of mid-plate hotspot swells are simulated numerically as an oceanic plate rides over a hot, upwelling mantle plume. The transient heat transfer equations, with time- and space-dependent boundary conditions, are solved in cylindrical coordinates. Geophysical data are used to constrain the models. Formation of the Hawaiian swell requires a mechanism of convective thinning of the lithosphere. The models constrain the Hawaiian heat source to have a maximum anomalous temperature of 250-300{degree}C, and a perturbing heat flux 5-6 times the background value. On the other hand, the Bermuda swell is likely produced by heat conduction due to weakness of the heat source. In part 2, an analytic model of axisymmetric mantle plumes is presented. Plume parameters beneath the lithosphere, which are constrained from the swell models, are used to infer the plume source regions. The Hawaiian plume likely originates near the core-mantle boundary, but other hotspots may have shallower sources. Chemical plumes are much narrower than thermal plumes because of low chemical diffusivity in the mantle. For mantle plumes driven by combined thermal-chemical diffusion, the chemical signature of the source regions may only be observed near plume centers. Finally, melt generation and extraction along the Hawaiian volcanic chain are discussed in part 3. As a part of the plate moves over the heat source, melting largely takes place in the region where the lithospheric material is engulfed and swept away by the flow of the heat source. At least three mantle components must be involved in the melt generation: the plume material, the asthenosphere, and the engulfed lithospheric material.

• Research Organization: Arizona Univ., Tucson, AZ (USA)
• OSTI ID: 6403659
• Country of Publication: United States
• Language: English

Related Subjects

15 GEOTHERMAL ENERGY
150100 -- Geothermal Energy-- Resources & Availability
150200* -- Geology & Hydrology of Geothermal Systems
ENERGY
ENERGY SOURCES
EVALUATION
GEOCHEMICAL SURVEYS
GEOTHERMAL ENERGY
HEAT FLOW
MATHEMATICAL MODELS
RENEWABLE ENERGY SOURCES
SURVEYS
VOLCANISM