[Originally published in 1989 as Kansas Geological Survey Subsurface Geology Series 12. This is, in general, the original text as published. The information has not been updated.]
The complete volume is available as an Acrobat PDF file (5.6 MB).
This volume contains a collection of summary papers from presentations made at the conference on "Sedimentary Modeling: Computer Simulation of Depositional Sequences" held at the Kansas Geological Survey in Lawrence, Kansas, on October 13, 1989. The idea to hold a conference was initiated in recognition of 100 years of continuous service by the Survey and of the recent advances in sedimentology that incorporate sequence-stratigraphic concepts, computer modeling, and related methods that help refine our interpretations of the stratigraphic record. We are at the threshold of a new era in geology where various field, laboratory, and conceptual relationships can be interpreted through computer simulations. Although the scales of space and time dealt with in modeling are immense and the parameters are complex, systematic collection of data followed by simulation modeling may reap significant rewards for geologic predictions. It was our goal to incorporate into one meeting a group of sedimentologists, paleontologists, and modelers to address the following themes: 1) current computer models of sedimentary rocks, 2) applicability of models to the rock record, 3) limitations and assumptions of models, and 4) where the future leads for modeling. The objectives of the meeting are not to reach a consensus, but to present and discuss current ideas and approaches, facilitate further communication, and heighten awareness on subjects we believe will become increasingly important in sedimentologic studies.
This conference volume contains 32 papers on a variety of subjects that are important, either directly or indirectly, in sedimentary modeling. Several papers focus on the current use of simulation models, including forward, inverse, and basin-analysis modeling. Some other papers are concerned with the controlling parameters important to modeling, such as estimating sea-level changes and subsidence patterns and their effects on sedimentation, accumulation rates, effects of global or stratigraphic forcing, periodicity in cyclic sediments, and lag time or breaks in sedimentation. Other papers illustrate the importance and usefulness of diagenesis, paleotectonic considerations, subsurface techniques (high-resolution seismic, wireline logs), and paleontology/paleoecology in sedimentary modeling. Several papers concentrate on various aspects of the midcontinent Pennsylvanian strata or "cyclothems." These midcontinent-focused papers provide a springboard in carrying the conference themes to the post-conference field trip that will examine the Pennsylvanian-age Lansing and Kansas City groups in a shelf-to-basin setting between Kansas City, Kansas, and Chanute, Kansas. The field trip will focus on the application of sequence-stratigraphic concepts to these outcropping strata and to analogous near-subsurface strata. By incorporating these concepts and other new methodologies in the study of cratonic strata, we may be able to develop, test, and refine computer-simulation models of depositional and diagenetic features that will be useful for locating natural resources in Kansas.
The Kansas Geological Survey is celebrating its centennial of continuous service to the state of Kansas in 1989 with this conference, much the same as the Survey celebrated its "other" centennial in 1964 (the KGS was initially started in 1864, but was closed from 1866 to 1889). The 1964 "Symposium on Cyclic Sedimentation" resulted in a benchmark symposium volume edited by D. F. Merriam (1964). The 1964 symposium volume included an insightful introduction by W. W. Hambleton (then Associate Director of the KGS); many of his comments are still valid for our conference, some 25 years later. The following are two excerpts from that introduction (Hambleton, 1964, p. v.):
Since the beginnings of the science of geology, geologists have generated models to explain observable phenomena. Often, the model was based upon an experience factor, and one could look for and recognize a pattern in information that could be related to previously encountered models. However, the generation of a model is not always simple because problems are rarely simple, and one may be faced with the evaluation of many interacting parameters.
Our notions about the tectonic and stratigraphic boundary conditions of sedimentary environments, for example, have long been controlled by models that may have outlived their usefulness and only by imaginative and systematic studies can we look to new models.
The fact that 25 years later the same statements are appropriate for our conference on sedimentary modeling underscores the extreme complexity of interpreting the rock record and understanding the interplay of the many variables that interact to create the sedimentary rock record. We can not yet duplicate exactly what is observed from the rock record in an experiment, in large part due to the vast mount of time required for geologic processes to occur. We can only approximate geological processes. An incomplete rock record allows only limited observable features available to describe a depositional system. The interaction of large- and small-scale events (time and space) was likely important in creating the rock record, yet the large-scale nature of the rock record limits the ability to sample, recognize, and describe small-scale features. Sedimentation rates, accumulation rates, and duration of hiatal surfaces are relatively poorly understood variables today, but with more rigorous studies they will likely form the foundation for more realistic models.
Despite the seemingly overwhelming problems that face sedimentary geologists, progress has been made over the last 25 years toward quantification of process-response relationships. The approaches and concepts used in collecting and interpreting data on sedimentation and stratigraphy are becoming increasingly more accurate and precise due to advances in biostratigraphy, paleoecology, subsurface studies, and seismic- and sequence-stratigraphic concepts. Other methods and new technological advances are providing increased resolution of both small- and large-scale features of the stratigraphic record (e.g., seismic-reflection profiling, wireline logging, chemical stratigraphy). The demand for greatly improved geologic prediction (e.g., reservoir characterization to predict bypassed oil and gas in existing fields) is resulting in interdisciplinary studies that provide independent data, useful in modeling, to test and verify stratigraphic and sedimentologic interpretations. Computing facilities are becoming more available and accepted for sophisticated computing tailored to managing larger data sets in shorter time periods, solving geologic problems, and for simulation modeling of the sedimentary record.
Computer-simulation modeling, a theme of this conference, holds exciting possibilities in helping resolve long-outstanding geologic problems. For example, modeling provides the means to 1) empirically test interactions of causal mechanisms of sedimentary sequences, 2) test and improve accuracy and precision of data collection and interpretation, 3) encourage interdisciplinary study and independent verification of data, 4) identify new areas of problem-oriented research, and 5) eventually permit prediction of sedimentary sequences. Computer-simulation models in use today include forward models (process-response), inverse models (rock to process, in time), simulations of sedimentary processes, simulations of stratigraphic units, and geometric models (concerning stratal elements). However, computer models are only as useful as the parameters used to define the models. There is good reason to believe that sedimentary modeling will be greatly improved as more problem-oriented interdisciplinary studies are conducted to acquire independently verifiable parameters that are accurate and precise, thereby providing improved constraints to models.
The challenge today in sedimentary geology and modeling is to extend the lower limit of resolution through improved problem development and more systematic and sophisticated quantitative data collection and analysis. Integrated or collaborative investigations using current concepts and technologies may be the best means to address these problems. Moreover, interdisciplinary studies can provide a means to corroborate results and improve interpretations. We hope that this conference provides a means to stimulate thought on the problems and potential of quantitative sedimentary analysis and simulation.
The planning and organization of a successful conference and field trip requires the combined efforts of many individuals and institutions. We thank the Kansas Geological Survey for administrative and logistic services. Conference and field-trip expenses were offset by generous contributions from the Kansas Geological Survey, Continuing Education and Academic Affairs Divisions of the University of Kansas, the Kansas Geological Foundation, and Arco Oil and Gas Company.
We are grateful to K. Kappleman and the Division of Continuing Education for handling much of the budgeting, planning, and logistical details before and during the conference and field trip. R. Buchanan's help with initial conference planning and publication procedures is greatly appreciated. We give our sincere thanks to the reviewers for their time and expertise on early versions of the summary papers in this volume. Members of the Petroleum Research Section of the Kansas Geological Survey, in particular C. G. Maples, D. L. Baars, and K. D. Newell were helpful in numerous ways throughout the development of the conference and field trip. We wish to thank L. A. Davidson for secretarial and word-processing services, J. Charlton for processing photographs, and S. Larson for preparing rock samples and thin sections. We thank M. D. Adkins-Heljeson, J. Sims, and R. Hensiek for timely drafting, technical editing, and arrangement of the manuscripts into the final format of this volume. The willing and able help of Kansas Geological Survey and University of Kansas graduate students, S. Roth, R. Fillmore, M. Lambert, D. Lehrmann, R. Abeg, J. Johnson, and J. Youle helped make for a more smoothly run conference and field trip.
Evan K. Franseen
W. Lynn Watney
Kansas Geological Survey
Kansas Geological Survey
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Web version May 12, 2010. Original publication date 1989.