Application of Seismic Reflection Configuration to Stratigraphic Interpretation
Seismic stratigraphy is basically a geologic approach to the Stratigraphic interpretation of seismic data. The unique properties of seismic reflections allow the direct application of geologic concepts based on physical stratigraphy. Primary seismic reflections are generated by physical surfaces in the rocks, consisting mainly of stratal (bedding) surfaces and unconformities with velocity- density contrasts. Therefore, primary seismic reflections parallel stratal surfaces and unconformities. Whereas all the rocks above a stratal or uniformity surface are younger than those below it, the resulting seismic section is a record of the chronostratigraphic (time-stratigraphic) depositional and structural patterns and not a record of the time-transgressive lithostratigraphy (rock-stratigraphy).
Because seismic reflections follow chronostratigraphic correlations, it is not only possible to interpret postdepositional structural deformation, but also it is possible to make the following types of Stratigraphic interpretations from the geometry of seismic reflection correlation patterns: (1) geologic time correlations, (2) definition of genetic depositional units, (3) thickness and depositional environment of genetic units, (4) paleobathymetry, (5) burial history, (6) relief and topography on unconformities, and (7) paleogeography and geologic history when combined with geologic data. However, one limiting factor is that lithofacies and rock type can not be determined directly from the geometry of reflection correlation patterns.
To accomplish the geologic objectives just listed, we recommend the following three-step interpretational procedure: (1) seismic sequence analysis; (2) seismic facies analysis; and (3) analysis of relative changes of sea level.
Seismic sequence analysis is based on the identification of stratigraphic units composed of a relatively conformable succession