Fundamental Concepts of Sequence Stratigraphy
The objective of this chapter is to introduce the fundamental concepts of sequence stratigraphy. These fundamental concepts comprise the basic factors and processes that control basin-fill patterns. We will define depositional sequences, discuss how they form, and in the process review a number of variations and problems that have been the subject of recent debate. It is essential to understand these factors and processes as well as the implications of the debates concerning various definitions in order to 1) effectively apply these concepts to specific geologic settings, and 2) to gain a deeper appreciation of the significance of the key contentious issues in this discipline. We propose a number of modifications to the sequence stratigraphic concepts. These include 1) elimination of type 1, type 2 sequence nomenclature, replacing it with a single sequence boundary type, 2) identification of shelf ridges as a potentially significant component of transgressive systems tracts, and 3) recognition that incised valleys in some instances can be restricted to outer-shelf and inner-shelf coastal-prism settings, with the unincised lowstand feeder systems referred to as lowstand bypass channel systems. These and other modifications are refinements of the sequence stratigraphic approach that have come to light as a result of extensive application of these concepts. emphasis placed on unraveling the cause-and-effect relationships between these factors and resultant stratigraphy. In addition, sequence stratigraphy has sought to better understand the linkage between coeval sedimentary systems in different depositional settings. Consequently, the effect of such factors as changes of sea level and sediment
Figures & Tables
Siliciclastic Sequence Stratigraphy-Concepts and Applications - Sequence stratigraphy has experienced a virtual explosion of applications in recent years. During that time, the concepts upon which sequence stratigraphy is based have been evolving to conform to new observations as well as new types of data. This volume summarizes the current status of this discipline as it applies to siliciclastic deposits. The emphasis in this volume is on sequence stratigraphy as an ?approach? to geological analysis, rather than as a model to which all data sets must conform. The expression of sequence architecture and the nature of bounding surfaces is illustrated through examples and applications drawn from a range of data types, including outcrop, core, wireline log, and 3-D seismic data. In addition, sequence expression also is illustrated using examples of modern landforms.