A reduced-gravity ocean model is used to determine the pattern of upwelling in the Cenomanian Atlantic. The deposition of organic-rich sediments on the margins of the equatorial region is found to be consistent with the patterns of upwelling in simulations which incorporate only a shallow (≤300m) equatorial connection between the North and South Atlantic. Fracture zone ridges were probably responsible for the effective shallowness of the gateway. If a deep equatorial channel is assumed the modeling results are consistent only with the more recent, Turonian, sedimentary record. We suggest, therefore, that reduced-gravity models provide a mean of predicting areas of the continental margins which may be underlain by hydrocarbon-rich sedimentary rocks. ¿ 1999 American Geophysical Union