Chapter 7 - Sequence stratigraphic framework

Abstract

This chapter explores the roles of scale and time in sequence stratigraphy, which are among the most subtle and critical aspects of stratigraphic research. Scale has implications for practical applications and the principles that guide the classification and nomenclature of stratal units and bounding surfaces. Time-stratigraphic relationships also play a key role in testing the relative contributions of global and local controls to the 3D stratigraphic architecture. The sequence stratigraphic framework records a nested architecture of stratigraphic cycles, which can be classified starting from the first-order basin fill. At each scale of observation, stratigraphic cycles define sequences, which consist of systems tracts and depositional systems. Scale-variant systems of stratigraphic nomenclature have also been proposed, but are undermined by the lack of reproducible standards for the definition of a sequence as an anchor for classification. Despite the nested architecture of cycles, the stratigraphic framework is not truly fractal, as sequences of different scales, as well as sequences of similar scales, may differ in terms of underlying controls and internal composition of systems tracts. The timing, the scales, the origins, and the internal makeup of sequences are basin specific, reflecting the local conditions of accommodation and sedimentation. The architecture described by the local stacking patterns, at scales selected by the practitioner or imposed by the resolution of the data available, overrides any model assumptions in the process of constructing a sequence stratigraphic framework.