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Paleoclimatic Expert System that Predicts Coastal Upwelling

Christopher R. Scotese

An expert system has been developed that models paleoclimate for any specified paleogeographic configuration. The program generates atmospheric pressure values and contours them to produce maps of atmospheric pressure for past times of known land, sea, and mountain distribution. Wind vectors are determined, based on the pressure gradient and Coriolis effect, and the direction of the winds is then compared with the azimuths of paleocoastlines to predict likely sites of coastal upwelling. Organic-rich muds form in such places today; thus upwelling predictions from paleoclimate models may provide clues about the distribution of potential petroleum source rocks. These predictions proved satisfactory for the Late Jurassic and mid-Cretaceous (Cenomanian), the two times for whic maps of organic-rich rocks were readily available.

The expert system is a formulation of published procedures to produce the paleoclimatic reconstructions. These algorithms use a parametric approach to model the major features of the earth's climatic system: differential heat capacity of land and sea, seasonality, continentality, ocean effect, and mountain effect. The main advantage of the parametric approach is that the program is easily modified and inexpensive to run. Through the paleoclimate maps derived by this approach are necessarily preliminary, they offer a reasonable best guess as to the earth's climate in the past. Eventually, more sophisticated computer modeling techniques may provide better results.

AAPG Search and Discovery Article #91038©1987 AAPG Annual Convention, Los Angeles, California, June 7-10, 1987.