Modeling Geologic History with Balanced Paleogeographic Maps

Christopher A. Shaw, William W. Hay

Using the principles of uniformitarianism, mass balance, and sedimentary cycling, an erosion-sedimentation-tectonic model has been developed to produce paleogeographic maps to describe the geologic history of the northwest Gulf of Mexico and the Western Interior source areas. The initial inputs are (1) boundaries of the sedimentary system (source and sink); (2) present-day average elevation of 1° squares within the boundaries; and (3) a stratigraphic column for each 1° square. Paleotopography is calculated by an iterative process involving replacement of sediment to the source area and calculation of erosion and uplift rates. The maps are considered properly balanced when erosion of the predicted paleotopography over a given time interval yields the correct sedi ent volumes in the right places. As far back as the latest Cretaceous, the paleogeography predicted by the model is remarkably close to that suggested by other studies even though no external information on tectonics is supplied. For paleogeographies older than Campanian, input on tectonics outside the boundaries is required to generate realistic maps. The balanced paleogeographic maps are a new tool useful for exploring many aspects of basin development, including thermal history.

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