ABSTRACT: Intraplate Stresses and Continental Margin Stratigraphy: New Constraints on the Relative Contributions of Tectonics and Eustasy to the Record of Sea Level Changes

Siergh Cloetingh, Henk Kool

Recent advances in modeling the tectonics of intraplate regions have established a causal relation between changes in plate-tectonic regimes and short-term changes in the orientation and magnitude of stress fields in the lithosphere. These temporal changes in stress produce vertical motions of the crust with a rate and magnitude consistent with magnitudes inferred from records of (apparent) sea level changes. Stress-induced vertical motions of the lithosphere could provide a tectonic explanation of short-term changes in sea level, such as the second-order and third-order Exxon cycles.

The sea level record can be used as an independent source of information for the analysis of paleostress fields in the plates. Geodynamic modeling studies were conducted, therefore, to discriminate the relative contributions of tectonics and glacio-eustasy to the apparent sea level record and to discriminate global vs. regional tectonic components in the sea level record. Modeling strongly suggests that even in a passive margin tectonic setting, the effects of tectonics generally overwhelm eustatic contributions to the sea level record. The studies also show a close correlation between changes in intraplate-tectonic regimes in the North Atlantic caused in plate kinematics and plate interactions and the timing of changes in sea level shown in "global" Exxon charts. These results sugges that the charts, which are based primarily on data from the northern/central Atlantic and the North Sea, reflect to a large extent the plate-tectonic evolution of this area. Apart from emphasizing the need to develop further rigorous stratigraphic criteria to separate of tectonics and eustasy on an intrabasinal scale, the studies emphasize the need to test the Vail concept in areas outside the North Atlantic. For this purpose, stratigraphic modeling for continental margins of other ocean basins based on recent ODP (Ocean Drilling Program) data, e.g., from the Indian Ocean, are presented.

AAPG Search and Discovery Article #91003©1990 AAPG Annual Convention, San Francisco, California, June 3-6, 1990