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AAPG Annual Convention and Exhibition

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A Simplified Guide For Sequence Stratigraphy: Nomenclature, Definitions and Method


Sequence Stratigraphy is not part of any stratigraphic code in the world. Reasons for not including Sequence Stratigraphy in the stratigraphic code vary. Complaints include: cumbersome nomenclature; conflicting or obscure causing mechanisms; disagreement on basic definitions, primarily in the basic approach to define surfaces and systems tracts; or simply that Sequence Stratigraphy is a “young” science that might need more time to mature. It is interesting to note that Biostratigraphy— just as old as Sequence Stratigraphy— has a very clear set of rules and terminology, or “code,” followed by all biostratigraphers. In fact, Biostratigraphy has the same set of challenges as Sequence Stratigraphy: it has a very cumbersome nomenclature classification of fossils; driving mechanisms for rate of evolution of different taxa is subject of debate; there is strong disagreement as how to classify different species and genera; and it is a relatively young science. Perhaps success in the paleontological community is linked to their approach for defining a code. Biostratigraphy is codified as a method, not a science, based on simple criteria that can be directly observed from available data. Implications for interpretation, in terms of causal mechanisms, follow after initial interpretation, and are not part of the code. This talk emphasizes the original intent of Sequence Stratigraphy: a method to interpret geologic data. As such, a Sequence Stratigraphic code should be based on criteria directly observable from outcrop, core, well-log, and seismic data— independent of causal mechanisms, duration, or magnitude of events. Similar to the biostratigraphers' code, this proposed approach leaves the interpretation of causal mechanisms as a step after the definition of surfaces and systems tracts. In this presentation, rather than proposing a code per se, we offer guidelines for interpretation and updated definitions of classical terms, which are slightly modified from the original definitions. Our modifications are intended to emphasize observational criteria, as well as clarify communication of terminology through the use of a set of translation terms taken from literature. We will also present the application of our proposed method to different data sets in order to show the step by step practical application of this method.