Genetic stratigraphic sequences in basin analysis; II, Application to Northwest Gulf of Mexico Cenozoic basin

The northwest Gulf of Mexico Cenozoic sedimentary wedge illustrates the application of genetic stratigraphic sequence analysis and documents several general conclusions. (1) Sequences defined by regional marine flooding are the principal genetic stratigraphic units of the basin fill. Continental margins are characterized by repetitive episodes of basin-margin offlap punctuated by periods of transgression and marine flooding of the depositional platform. (2) Continental margin outbuilding is concentrated at one or more shelf-edge deltaic depocenters separated by interdeltaic bights. Depocenters remain fixed during a depositional episode but commonly relocate during transgression and flooding. (3) A distinct syndepositional structural style in prograding continental margins results in sporadic uplift of a basin-fringing peripheral bulge and accentuates preservation of shelfmargin facies along zones of extensional normal faulting and enhanced subsidence. (4) Genetic stratigraphic sequences commonly reflect an evolving interplay among two or even three variables. For example, early Cenozoic Gulf sequences are most closely related to tectonic events of the intraplate source terrane, which, in turn, affect rate and location of sediment supply and basin-margin response to loading. Late Cenozoic sequences more closely reflect proposed eustatic cycles.