Predictable Variations in the Marine Stratigraphic Record of the Northern and Southern Hemispheres, and Reservoir Potential

Martin A. Perlmutter: Texaco Inc., Houston, TX; and Roy E. Plotnick: University of Illinois, Chicago, IL

Abstract

Variation in the phase relationships of precession-scale sediment yield cycles and glacioeustatic cycles may cause systematic differences in the marine stratigraphy of the Northern and Southern Hemispheres. These differences should be evident in lithology bed thickness and distribution.

At precession-scale (~20 kyr), Northern and Southern Hemisphere insolation cycles are 180 degrees out of phase. Consequently, similar climatic successions in opposite hemisphere, and associated sediment yield cycles can be 180 degrees out of phase, as well. Prior to the Plio-Pleistocene, the common glacial condition has been a unipolar icecap. Under this condition, precession-scale eustasy will tend to track the insolation cycle of the glaciated hemisphere. Consequently, similar climatic successions in opposite hemispheres can generate yield cycles having distinctly different phase relationships to glacioeustasy. Such differences should not exist in an ice-free world.

If correct, this hypothesis will significantly improve stratigraphic interpretations leading to more accurate exploration analyses by being able to high grade which regions are most prone to sand-rich submarine fans. In addition, it will lead to a more complete understanding of the paleoclimate record by being able to determine whether a particular interpreted sea level shift occurred as a result of glaciation, or a more local forcing agent.