SATELLITE GRAVITY AND THE GEOSPHERE: Contributions to the Study of the Solid Earth and Its Fluid Envelope by Committee on Earth Gravity from Space

Author:Committee on Earth Gravity from Space
Language: eng
Format: epub
Tags: Earth Sciences
Publisher: NATIONAL ACADEMY PRESS
Published: 1997-09-02T00:00:00+00:00

Other key questions in mantle dynamics concern the nature of mantle plumes, which are a major source of intraplate volcanism and enhanced heat flow. Gravity changes within plates that could be associated with mantle plumes can be as large as 10 mGal, but resolutions of approximately 1 mGal at the shorter wavelength limit down to ~10−2 mGal at the longer wavelength limit need to be obtained to characterize smaller, though important, variations in thermal structure and to distinguish between various models of mantle structure. For a mission flown at 400 km, the ~10−2 mGal accuracy level is met by SGG and SST for resolutions of 400 km and larger, and by SSI for resolutions of 300 km and larger. Separation of the longer-wavelength mantle structure effects from those caused by other phenomena will clearly be a challenge with current technology. However, the situation is more favorable for questions that require shorter wavelength measurements, such as the depths of origin of mantle plumes. To constrain plume depths it will be necessary to isolate the effects of dynamic upwelling from signals associated with lithospheric processes, which will require gravity resolution of approximately 1 mGal over length scales of order 100 km. As shown in Figure 2.13, three of the generic missions (SGG, SST, and SSI) at 400 km would provide 1-mGal-level measurements down to the necessary resolution levels of 100-200 km.

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