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Computer-Generated Late Cretaceous Oceanic Circulation Model

Memorie K. Yasuda, Eric J. Barron, Robert G. Douglas

Simulations of Campanian and present-day ocean circulation were generated using an adapted version of the numerical ocean model created by Semtner. Model input for the Campanian simulation includes paleogeography provided by Barron et al; paleodepths based on the Sclater-Francheteau age-depth relationship; and atmospheric parameters (sea-surface temperature, meridianal and latitudinal wind stress, precipitation, and evaporation) which are derived from a mean annual version of the National Center for Atmospheric Research spectral general circulation model.

The model has a horizontal resolution of 5° latitude by 5° longitude and recognizes the presence of up to four vertical ocean grid boxes with thicknesses of 50, 450, 1,500, and 2,000 m. The model is driven by atmospheric forcing and uses the numerical scheme of Bryan based on primitive equations for a hydrostatic Boussinesq ocean with a rigid lid.

The model produces global plots at each vertical ocean level for temperature, salinity, u-velocity, v-velocity, current vector, and stream function. Plots are also produced for heat flux, ice thickness, and vertical velocity. With this output, we focus on the problems of locating bottom-water sources and areas of high surface water productivity. The Campanian was selected since the different distribution of continents and oceans resulted in a period of relatively warm global temperatures with the existence of marginal seas in evaporative zones providing the best case for the possibility of high-salinity, low-latitude bottom water. In addition, we address the practical problem of locating potential upwelling areas since the close link to high surface water productivity is a major contr buting factor to the deposition of organic-rich sediments.

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