Sequence stratigraphy

Article By:

Miall, Andrew D. Department of Geology, University of Toronto, Ontario, Canada.

Last reviewed:January 2020

DOI:https://doi.org/10.1036/1097-8542.757371

The study of stratigraphic sequences, defined as stratigraphic units bounded by unconformities. L. L. Sloss was the first to formally establish, in 1963, that Phanerozoic cratonic successions in North America could be subdivided into six broad sequences that spanned the entire interior of the continent. However, his work was based on widespread knowledge among North American petroleum geologists, going back to E. Blackwelder in 1909, that the stratigraphy of the continent could be subdivided into a limited number of unconformity-bounded sequences. In later work, Sloss and others demonstrated that these sequences could be correlated partially or entirely with similar successions within other continental interiors, in Russia and South America. With improvements in the acquisition and processing of reflection-seismic data by petroleum exploration companies, in the 1970s came the recognition that unconformity-bounded sequences could be recognized in most sedimentary basins. This was the beginning of an important development, seismic stratigraphy, which also included the use of seismic reflection character to make interpretations about large-scale depositional facies and architecture (Fig. 1). These breakthroughs were accompanied by the proposal by Peter Vail that the bounding unconformities are generated by erosion resulting from eustatic (worldwide) changes in sea level and they are therefore correlatable worldwide. These developments were rapidly accepted within the petroleum industry and brought about a revolution in stratigraphy that is still under way. See also: Seismic stratigraphy; Unconformity

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