Sequence Stratigraphic Setting of Deepwater Systems
Sequence stratigraphy is the study of sedimentary rocks within a temporal framework. The basic premise is that marine sedimentary rocks were deposited in a series of cycles that result from the relative fall and rise of sea level. The depositional pattern can vary widely from basin to basin, depending on variations in sediment supply and basin tectonics.
The fundamental mapping unit of sequence stratigraphy is a depositional sequence. Vail et al. (1977) defined a depositional sequence as “a stratigraphic unit composed of a relatively conformable succession of genetically related strata and bounded at its top and base by unconformities or their correlative conformities.” Depositional sequences can be mapped using seismic, wireline-log, and outcrop data.
Sequence stratigraphy is distinguished from other paradigms by its interpretation of strata within a chronostratigraphic framework. Chronostratigraphy can be determined using different types of data sets. High-resolution biostratigraphy is essential to dating sequences and determining paleoenvironments. Correlation of bedding (stratal) surfaces defines time lines on the basis of physical stratigraphy. Finally, seismic reflections are generated at stratal boundaries and tend to follow them within the limits of seismic resolution. Thus, seismic reflections, with certain exceptions, represent time lines within the limits of their resolution. This key chronostratigraphic feature makes seismic reflections ideal tools for defining the chronostratigraphy of a sedimentary basin and for correlating strata.
The most controversial aspect of sequence stratigraphy is that sequence boundaries of the same age can be found in basins worldwide; therefore, sequence boundaries are considered to be caused