A Skeptic’s Conclusion:
The Model-based Clastic Sequence Stratigraphic Paradigm Was and Is Fatally Flawed.*
William E. Galloway1
Search and Discovery Article #70020 (2006)
Posted August 4, 2006
*Oral presentation at AAPG-SEPM Annual Convention, Houston, Texas, April 9-12, 2006. SEPM Forum: High-Resolution sequence stratigraphy: Is the Model Breaking Apart
1University of Texas, Austin, Texas ([email protected])
A “sequence boundary” is a conceptual surface that is a composite of multiple physical stratigraphic surfaces.
The composite fluvial incision surface is demonstrably not a single, regionally isochronous boundary.
Basin paleogeography is a 3D mosaic of sediment dispersal systems that cannot be captured by 2D models.
Corollary: Clastic sediment supply rate and texture are not uniquely predictable by base level change history.
The sequence model and terminology inadequately reflects the diversity of slope and basin facies.
Fluvial entrenchment surface
Regressive ravinement surface
Transgressive ravinement surface
Shelf/slope starvation surface
Shelf erosion (“deflation”) surface
Slope entrenchment surface
(see Figure 1)
Maximum flooding surface
Mississippi/Red River System
Features Associated with Deepwater Megaslide
Otvos, E.G., 2005, Chronology of Gulf coastal plain and valley terrace aggradation during Pleistocene lowstands. Limitations of base level control: Quaternary International, v. 135, p. 91-113.
Note: concerning SEPM Forum: SEPM Forum: High-Resolution sequence stratigraphy: Is the Model Breaking Apart?
The objective of this forum was to have an open debate about the controversies associated with sequence stratigraphic interpretation in high resolution data sets. Several researchers are puzzled with questions arising from interpretation in high resolution surveys. What is the relationship between sea level and systems tracts during the last glacial cycle? Are the sequence stratigraphic surfaces in fact time transgressive? What surfaces are more likely to be synchronous? What are the implications for reservoir correlation and mapping? This research forum addresses these and other questions. Vitor Abreu (SEPM Research Councilor) moderated this forum, and seven invited guests from industry and academia led the discussion with different approaches and points of view. This allowed for different opinions to be expressed and defended on a scientific basis, and we hope shed a light on this controversial subject.