Chapter 3 - Controls on sequence development

Abstract

The stratigraphic record is shaped by the interplay of multiple allogenic and autogenic processes; the former operate across all stratigraphic scales, whereas the latter are typically restricted to the scales of high-resolution sequence stratigraphy. Nevertheless, the formation of any sequence stratigraphic surface whose timing is controlled at least in part by sediment supply can be affected by autogenic processes, which therefore remain important at all hierarchical levels. The rates, the periodicity, and the relative importance of allogenic and autogenic controls may vary with stratigraphic age and geological setting, making it difficult to generalize or quantify their relative contributions to the development of sequences. However, the interplay of all controls on the stratigraphic architecture boils down to accommodation and sedimentation, which explain the formation of stratal stacking patterns irrespective of the dominant controls at syn-depositional time. This keeps the methodology objective and focused on observational criteria, in a manner that is independent of the interpretation of the underlying controls on sequence development. Following the data-driven construction of 3D stratigraphic frameworks, sequence stratigraphy provides a benchmark for testing the extent of global vs. local controls on sedimentation and stratigraphic cyclicity. This chapter presents the allogenic and autogenic processes that contribute to the sequence stratigraphic framework, and introduces the key concepts that explain the formation of stratal stacking patterns: relative sea-level changes (proxy for accommodation) and base-level changes (proxy for sedimentation).