Sequence Stratigraphy: A Practitioner's Point of View

Louis M. Liro

Sequence stratigraphy has become the preeminent method for describing the cyclicity and architecture in sedimentary basins. In addition, sequence stratigraphy is now routinely used to evaluate exploration opportunities and to facilitate exploitation and development projects. The rapid development of sequence stratigraphic concepts and models, however, requires a careful consideration of the their applicability.

The greatest challenge is the need to address stratigraphy from multiple perspectives (autocyclic to basin-wide), often incorporating multiple datasets (thin section to seismic section). This challenge requires a multidisciplinary approach, tuned to the specific questions at hand.

Key to the application of sequence stratigraphy at any scale is the identification of a vertical fill profile. This is the best "value added" method in exploration, allowing the explorationist to rapidly characterize the stratal section and identify key stratigraphic elements (or their absence).

The use of scale-less, generalized models in stratigraphic evaluations should be discouraged. These models create unrealistic images of vertical fill, as well as presenting overly simplified depositional processes. It is more rational to identify the fill profile, and then draw on depositional models specific to the environment interpreted.

There has been much discussion of the relative merits of regional erosion surfaces ("sequence boundaries") and regional flooding surfaces as key correlation surfaces. In practice, the specific conditions in each study area dictate which (or both) correlation surfaces are useful.

AAPG Search and Discover Article #91019©1996 AAPG Convention and Exhibition 19-22 May 1996, San Diego, California