Fluvial Deposits and Facies Models
We have so far discussed different kinds of flow and stratification, and have considered how sedimentary structures can be used to define facies and facies sequences. Our first application of these ideas will be to fluvial systems, because, of all the natural environments, rivers most closely approach the simplest flow conditions discussed in Chapter 2. It is hardly necessary to point out that rivers are very much more complex than flumes, with complicated short and long term changes in discharge and velocity and shifts in channel position and base level that affect aggradation and preservation of sedimentary structures. However, the ideas of the earlier chapters can be applied to fluvial systems in their simplest form.
Figures & Tables
Structures and Sequences in Clastic Rocks
These notes are for a course on the use of primary structures and stratification sequence as tools for interpretation of depositional environments. The emphasis is to provide a concise review of the factors that had led to the renaissance in clastic sedimentology during the decade leading up to 1975. The attempt is to provide an organized summary of both experimental studies and ideas on bed forms and primary sedimentary structures that was then relatively new and to show how this information could be applied to solving geologic problems. A second broad objective of the course is more philosophical, in that there is an attempt to outline some general approaches to interpretation and convey the goals of interpretation. The authors believe that there are a fairly small number of general depositional settings but that numerous environmental and process variables within each general setting lend considerable variation to the deposits themselves. The emphasis is at the scale of features and sequence that can commonly be observed in individual outcrops or cores. Interpretation begins with data collected at this level.