The Impact of High-Frequency Climate Cycles on Exploration Strategy

Martin Perlmutter¹, Roy Plotnick², and Thomas Moore^3
1 ChevronTexaco, Bellaire, TX
² University of Illinois in Chicago, Chicago, IL
³ Argonne National Laboratory, Argonne, IL

The phase relationships of precession-scale sediment yield cycles and glacioeustatic cycles can cause systematic differences in the marine stratigraphy of the northern and southern hemispheres. These differences are evident in the variations in lithology, bed thickness and distribution and can impact the interpretation of reservoir potential.

Modeling and analysis indicate that the largest changes in insolation occur relatively rapidly, during periods of high eccentricity at the scale of precession. At precession-scale (~20 kyr), northern and southern hemisphere insolation cycles are 10 kyrs out of phase. The climate of one hemisphere is at a maximum while the other is at a minimum. Consequently, similar climatic successions in opposite hemispheres and associated sediment yield cycles will be 10 kyrs out of phase, as well. Prior to the Plio-Pleistocene, glacioeustatic cycles were controlled by the southern pole because the northern pole could not maintain a significant continental icecap. The result is that similar climatic successions in the northern hemisphere will have yield cycles with distinctly different phase relationships to glacioeustasy than the southern hemisphere. Such differences will not exist in an ice-free world.

Evaluating sediment delivery systems and sea level in context with climate change, permits forecasting and high grading of regions prone to maximum coarse yield in and around lowstands; conditions prone to the development of sand rich submarine fans. Where and when fan deposition had the highest probability of occurrence is a function of the existence of an icecap, the hemisphere and the regional climatic succession.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005