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Ridge spreading, subduction, and sea level fluctuations.
Science (New York, N.Y.)
|November 16, 1990
Summary
Sea level changes are complex, not just tied to ocean plate spreading. A numerical model reveals dynamic sea level shifts due to thermal structure changes, questioning past interpretations.
Area of Science:
- Geophysics
- Earth Science
- Oceanography
Background:
- Sea level fluctuations are traditionally linked to changes in oceanic plate spreading rates.
- Understanding the relationship between mantle dynamics and sea level is crucial for geological interpretations.
Purpose of the Study:
- To investigate the complex relationship between mantle convection, oceanic plate spreading, and sea level fluctuations using a numerical model.
- To challenge the simplistic view of sea level changes solely based on past oceanic spreading rates.
Main Methods:
- Development and application of a dynamic numerical model simulating mantle convection.
- Analysis of sea level responses to altered ridge spreading within the model.
- Examination of changes in the deep thermal structure of oceanic and continental lithosphere.
Main Results:
- Sea level exhibits a rapid rise followed by a gradual fall after increased ridge spreading, indicating a time-dependent response.
- These sea level dynamics are driven by significant alterations in the deep thermal structure beneath oceans and continents.
- The model suggests that inferring past sea level fluctuations solely from oceanic spreading rates may be unreliable.
Conclusions:
- Sea level fluctuations are not a simple function of oceanic plate spreading rates.
- Mantle convection and associated thermal structure changes play a critical role in driving dynamic sea level variations.
- More sophisticated models and improved stratigraphic data are needed to constrain mantle viscosity structure.
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