CARBONATE STRATIGRAPHY AND SEQUENCE STRATIGRAPHY: A 30-YEAR RETROSPECTIVE

The concepts of sequence stratigraphy set forth by Exxon nearly 30 years ago have led to one of the most significant paradigm shifts in sedimentary geology. These original tenets and their subsequent evolution into integrated methods of cycle stratigraphy have become the fundamental basis for observation, description, and interpretation of clastic and carbonate depositional sedimentary systems. Although strong opposition to these concepts was voiced after their introduction, critics have become largely silent in recent years. Instead, most stratigraphic studies now fully embrace them. I endorse this revolution in carbonate stratigraphy, but submit that there are important limitations and caveats to rock-based sequence stratigraphy that must be kept in mind.

Originally based on integrated 2-D subsurface geophysical data, true sequence stratigraphy can only be applied accurately in rock-based data sets where at least 2-D correlations can be defined along depositional dip. This is best accomplished in large-scale, continuous outcrops or in subsurface successions where core/log ties can be reliably made. In such settings, sequence stratigraphy is a powerful tool for defining temporal interrelationships among depositional surfaces, facies, and stratal bodies, and for elucidating sedimentation response to sealevel fall/rise accommodation cycles. However, in many settings e.g., conventional 1-D outcrops and poorly constrained subsurface data sets, meaningful application of sequence stratigraphic concepts is problematic at best. In these settings, the concepts of cycle stratigraphy, a much older paradigm, remain a powerful tool for interpreting carbonate successions and their temporal interrelationships.