SEPM Strata

parasequence

This relatively conformable succession of genetically related beds or bedsets (within a parasequence set) is bounded by marine flooding surfaces or their correlative surfaces (Van Wagoner, et al., 1988). This cycle of sediment is deposited penecontemporaneously, up-dip to down-dip, over a depositional surface. Parasequences are units that are commonly identified and used as major tools for core and well log correlation. Patterns of the stacking of parasequence sets are used in conjunction with boundaries and their position within a sequence to define systems tracts (Van Wagoner et al., 1988).

Thus a parasequence is commonly identified and separated from other parasequences by flooding surfaces and is often characterized by a cycle of sediment that either coarsens or fines upward. Thus the flooding surfaces are usually identified by abrupt and correlatable changes of the grain size of the sediments on either side of that flooding surface. This change in grain size is often caused by the abrupt changes in energy that are associated with the waves or currents of the sea transgressing across the sediment interface. These abrupt changes in grain size that bound a parasequence are used to identify them in well logs, outcrop and seismic and are also used to identify a parasequence cycle. Examples of these grain size changes can be seen in the parasequences of tidal flats, beaches, and deltas.

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Useful References
Catuneanu, Octavian, William E. Galloway, Christopher G. St. C. Kendall, Andrew D. Miall, Henry W. Posamentier, André Strasser, and Maurice E. Tucker, 2011,"Sequence stratigraphy: Methodology and Nomenclature", Newsletters on stratigraphy, Stuttgart, Vol. 44/3, 173–245
Helland-Hansen, W., Martinsen, O.J., 1996, Shoreline trajectories and sequences: description of variable depositional-dip scenarios. Journal of Sedimentary Research 66 (4), 670–688.
Holbrook, John M., and Janok P. Bhattacharya, 2012, Reappraisal of the sequence boundary in time and space: Case and considerations for an SU (subaerial unconformity) that is not a sediment bypass surface, a time barrier, or an unconformity, Earth-Science Reviews 113, 271–302
Hunt, D., Tucker, M.E., 1992, Stranded parasequences and the forced regressive wedge systems tract: deposition during base-level fall. Sedimentary Geology 81, 1–9.
Jervey, M.T., 1988, Quantitative geological modeling of siliciclastic rock sequences and their seismic expression, in Wilgus, C.K., Hasting, B.S., Kendall, C.G.St.C, Posamentier, HW, Ross, CA, and Van Wagoner, JC, eds., Sea-level changes: an integrated approach: Tulsa, OK, Society of Economic Paleontologists and Mineralogists, Special Publication No. 42, p. 47-69.
Miall A., 1985, architectural elements and boundaries: A new method of facies analysis applied to fluvial deposits: Earth-Science Reviews, v, 22, p. 261-308
Nummedal, D., Riley, G.W., Templet, P.L., 1993, High-resolution sequence architecture: a chronostratigraphic model based on equilibrium profile studies. In: Posamentier, H.W., Summerhayes, C.P., Haq, B.U., Allen, G.P. (Eds.), Sequence stratigraphy and Facies Associations, vol. 18. International Association of Sedimentologists Special Publication, pp. 55–68.
Pickering, K. T., D. A. V. Stow, M. P. Watson, and R.N.Hiscott, 1986, Deep-water facies, processes and models: a review and classification scheme for modern and ancient sediments: Earth Science Reviews, v. 23, p. 75–174.
Posamentier, H.W., Jervey, M.T., Vail, P.R., 1988, eustatic controls on clastic deposition. I. Conceptual framework. In: Wilgus, C.K., Hastings, B.S., Kendall, C.G.St.C., Posamentier, H.W., Ross, C.A., Van Wagoner, J.C. (Eds.), Sea Level Changes––An Integrated Approach, vol. 42. SEPM Special Publication, pp. 110– 124.
Posamentier, H.W., Allen, G.P., 1999. Siliciclastic sequence stratigraphy: concepts and applications. SEPM Concepts in Sedimentology and Paleontology no. 7, 210 p
Sprague,A. R., P. E. Patterson, R.E. Hill, C.R. Jones, K. M. Campion, J.C. Van Wagoner, M. D. Sullivan, D.K. Larue, H.R. Feldman, T.M. Demko, R.W. Wellner, J.K. Geslin, 2002, The Physical stratigraphy of Fluvial strata: A Hierarchical Approach to the Analysis of Genetically Related Stratigraphic Elements for Improved Reservoir Prediction, (Abstract) AAPG Annual Meeting

Van Wagoner, J.C., Posamentier, H.W., Mitchum, R.M., Vail, P.R., Sarg, J.F., Loutit, T.S., Hardenbol, J., 1988, An overview of sequence stratigraphy and key definitions. In: Wilgus, C.K., Hastings, B.S., Kendall, C.G.St.C., Posamentier, H.W., Ross, C.A., Van Wagoner, J.C. (Eds.), Sea Level Changes––An Integrated Approach, vol. 42. SEPM Special Publication, pp. 39–45.

Van Wagoner, J.C., Mitchum, R.M., Campion, K.M., and Rahmanian, V.D. (1990), Siliciclastic sequence stratigraphy in Well Logs, Cores, and Outcrops. American Association of Petroleum Geologists, Tulsa, 55p.