Sequence stratigraphy of clastic systems: concepts, merits, and pitfalls

Abstract

Sequence stratigraphy is widely embraced as a new method of stratigraphic analysis by both academic and industry practitioners. This new method has considerably improved our insight into how sedimentary basins accumulate and preserve sediments, and has become a highly successful exploration technique in the search for natural resources. The different sequence stratigraphic models that are currently in use, i.e. three varieties of depositional sequences, a genetic stratigraphic sequence, and a transgressive–regressive sequence, all have merits and limitations. Each model works best in particular tectonic settings, and no one model is applicable to the entire range of case studies. Flexibility is thus recommended for choosing the model that is the best match for a specific project. Having said that, the existing sequence models also have a lot in common, with the main difference being in the style of conceptual packaging of the same succession of strata (i.e., where to pick the sequence boundaries). Sequence stratigraphic models are centered around one curve of base level fluctuations that describes the changes in accommodation at the shoreline. The interplay between sedimentation and this curve of base level changes controls the transgressive and regressive shifts of the shoreline, as well as the timing of all systems tract and sequence boundaries. Surfaces that can serve, at least in part, as systems tract boundaries, are sequence stratigraphic surfaces. Systems tract boundaries have low diachroneity rates along dip, which match the rates of sediment transport. These surfaces may be much more diachronous along strike, in relation to variations in subsidence and sedimentation rates. This paper presents the fundamental concepts of sequence stratigraphy, and discusses the merits and pitfalls of its theoretical framework. The deviations in the rock record from the predicted architecture of systems tracts and stratigraphic surfaces are also discussed.