Kansas Geological Survey, Subsurface Geology 12, p. 21
J. F. Read, M. Elrick, D. Osleger, S. Sriram, and V. Miranda
Department of Geological Sciences, Virginia Tech
Stratigraphic modeling done by the Virginia Tech group has concentrated on understanding how 1-30-m (3-99-ft)-thick (4th and 5th order) carbonate cycles are arranged to make up Vail-sequences (3rd order) of carbonate platforms. In carbonate sequences containing large numbers of 1-10-m (3-33-ft) carbonate cycles, lack of well-defined marker beds generally prevents construction of detailed stratigraphic cross sections showing complex facies changes. Fischer plots that graph cumulative cycle thickness, corrected for linear subsidence using average cycle period, can be used to correlate sections and show relation of individual cycle-types to 3rdorder sea levels. Interaction between simple or complex sea-level curves defined by various frequencies and amplitudes, the sediment-surface, water-depth-dependent sedimentation rate, lag-time, and subsidence through time can be shown using one-dimensional models. Isostatically balanced two-dimensional models that incorporate the above variables, plus initial platform slope and antecedent topography, thermotectonic subsidence (divided into rotational and regional components), sediment- and water-loading using an elastic-beam model, and erosion, can be used to construct synthetic cyclic-facies cross sections of carbonate platforms. These can be used to define regional relations between cycles, likely vertical- and lateral-facies changes, distribution of disconformities/conformities and tidal-flat caps, and relative water depths of facies likely to be developed on the platform, as well as likely location of early diagenesis. The integration of field and modeling studies (e.g., Koerschner et al., 1989; Read et al., 1986) provides a rigorous analysis of cycle deposition that could be of great predictive value in the exploration and development of petroleum reservoirs.
Koerschner, W. F., III, and Read, J. F., 1989, Field and modeling studies of Cambrian carbonate cycles, Virginia Appalachians: Journal of Sedimentary Petrology, v. 59, no. 5, p. 654-687
Read, J. G., Grotzinger, J. P., Bova, J. A., and Koerschner, W. F., 1986, Models for generation of carbonate cycles: Geology, v. 14, p. 107-110
Kansas Geological Survey
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Web version May 7, 2010. Original publication date 1989.