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Geodynamic evidence for a chemically depleted continental tectosphere.
1Department of Earth Sciences, University of Western Ontario, London, Ontario N6A 5B7, Canada. aforte@uwo.ca
Science (New York, N.Y.)
|January 11, 2000
Summary
The Earth's tectosphere, a layer beneath continents, is chemically depleted and cold, explaining continental stability. This distinct thermochemical structure differs from the oceanic mantle.
Area of Science:
- Geophysics
- Geodynamics
- Solid Earth Science
Background:
- The tectosphere, mantle beneath cratons, exhibits unique thermochemical properties.
- It's theorized to be depleted in basaltic components, possessing buoyancy.
- This buoyancy counteracts its colder temperature compared to the suboceanic mantle.
Purpose of the Study:
- To investigate the thermochemical structure of the Earth's tectosphere.
- To understand the factors contributing to cratonic stability.
Main Methods:
- Utilized inversions of geodynamic data.
- Employed tomography-based mantle flow models.
Main Results:
- Confirmed the tectosphere is chemically depleted.
- Determined the tectosphere is cold to a depth of 250 km.
- Identified an equilibrium between thermal and chemical buoyancy.
Conclusions:
- The tectosphere's distinct structure supports cratonic stability.
- Chemical depletion and thermal buoyancy are key to this stability.