Kansas Geological Survey, Computer Contributions 9, originally published in 1967
1Stanford University and 2University of Kansas
Originally published in 1967 as Kansas Geological Survey Computer Contributions 9.
Utilizing an IBM 7040 or 7094 computer, a mathematical model of marine sedimentation imitates the behavior of sediments as they are transported and deposited within a marine sedimentary basin. By mathematical means, in symbolic three-dimensional space, the model imitates the processes of tectonic warping, winnowing of sediments along beaches, formation of deltas, and growth and interaction of organism communities, including algal banks and coral reefs that populate the sea floor. The model is operated by assuming a set of external controlling conditions and feeding these into the computer as numerical data. The model is then run forward, by increments, through geologic time. Several million years of geologic history can be recreated in an hour or less of IBM 7040 computer time.
Output from the program representing the model is in the form of lithofacies maps, structure maps, biofacies maps, water depth maps, and up to six geologic cross sections that show both structure and facies relationships. An additional feature provides the output of mirror images of the cross sections if construction of a three-dimensional display is desired. A series of maps arid cross sections can be printed for each increment of geologic time, making it possible to observe progressive geologic changes as they occur.
The model is used as an experimental tool for observing the response to a set of assumptions. When a change in the data used to control the program is made, the model responds dynamically within a few seconds of computer time. Deltaic deposits, ancient beaches, algal reefs, and other sedimentary features develop progressively and undergo structural deformation with startling realism.
The principal objective in geological mathematical modeling is to produce symbolic geologic products (such as sedimentary strata) by imitating the principal geologic processes that produce the products. There is, however, uncertainty as to the mode of operation and relative importance of many processes. Consequently, assumptions may be made and tested on a trial and error basis. If the results of a computer run with the model do not agree well with reality (i.e. the symbolic deposits do not accord well with real sedimentary deposits that are being imitated), the assumptions can be progressively changed, and new runs made until the model begins to perform realistically.
The mathematical model is embodied in a FORTRAN IV computer program which has been successfully run on an IBM 7040 and IBM 7094 with satisfactory results. With minor modifications, the program can probably be used with computers of other manufacturers, and with IBM System 360 computers.
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Kansas Geological Survey
Placed on web Aug. 27, 2019; originally published 1967.
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