Seismic Sequence Analysis
Exercise Two

This is the second of a series of exercises in seismic sequence analysis provided by the USC sequence stratigraphy web site. The seismic line used in this exercise is a copy of Figure 39 from page 49 of the AAPG Atlas of the "Sequence Stratigraphy in Offshore South African Divergent Basins". This figure was chosen because it contains clear and easy to interpret examples of onlapping and downlapping sequence geometries and a relatively uncomplicated structural fabric.

The Atlas that the figure comes from has many other similar examples and was initially interpreted by Soekor (Pty) Ltd during their exploration for Cretaceous lowstand traps in the offshore of South Africa.

To gain access to the graphics image with the un-interpreted seismic section exercise, click on left image to download it (click here for a smaller version of same section). Print the file of the seismic and follow the procedures outlined in the introduction to interpret this. First identify the termination of seismic reflectors at discontinuity surfaces; then establish which of these surfaces form the sequence boundaries. Follow this by demarking the geometries of the sequences and the system tracts they include.

Working with a print of the downloaded seismic line:
1) From the base up identify and number the sequence boundaries. Also indicate the major faults.
2) Now indicate the positions of the system tracts including "Lowstand System Tracts", "Transgressive Systems Tracts" and "Highstand Systems Tracts".
3) Finally construct a chronostratigraphic chart for this seismic section using the methodology described in the section on Chronostratigraphy.

Click on left image to view a the solution and match it with your interpretation(click here for a smaller version of same section).