An Integrated Stratigraphic Framework Builder and Automated Mapping System

Jeffrey G. Pittman, David E. Hamilton

Computer mapping of geologic surfaces involves an often complicated decision-making process requiring knowledge of the appropriate sequence of operations needed to produce either a satisfactory cross section, isochore map, structure map, or volumetrics report. Mapping surfaces within stratigraphic sequences involving truncation and/or baselapping relationships between surfaces is time consuming for the experienced user and intimidating for the novice. This program saves the experienced user time and frustration and provides the less-experienced user insulation from the decision-making process. With continued use, this computer program is also an effective learning tool.

Logic in the program was developed through referral to other workers and through experimentation. The user first identifies each surface in the framework as an unconformity or depositional surface and then identifies the relationship of unconformities to adjacent sequences (i.e., discordant or concordant). The method used to construct surfaces in a sequence involves adding and/or subtracting thickness from the surface in the sequence that will make the best map (control surface). The user must identify the control surface in each sequence. Grids (computer representations of surfaces) for cross sections, isochore maps, structure maps, and volumes are constructed using information from the stratigraphic framework. For example, grids for a structural surface are blank in areas where eros on has removed that surface (truncation) and in areas beyond where the surface baselaps onto a lower unconformity. Truncation and baselap lines are also produced. Grid construction steps are automatically set up and submitted for execution. After these grids are built, the user may interactively create cross sections, maps, and volumetric reports.

AAPG Search and Discovery Article #91022©1989 AAPG Annual Convention, April 23-26, 1989, San Antonio, Texas.