LAB 08 – Sequence Stratigraphy
Names:
&
Note: you should turn in your own sheet. Put your name first and your partner’s second.
The following is intended to provide you with some hands-on experience in generating and interpreting
depositional sequences associated with the rise and fall of sea level. We will be using Fuzzim, the same
program that we played with in class last week. Each simulation follows the development of a delta
system across a nearshore/offshore profile. We will be examining different kinds of profiles, as well as
variations in sea level signatures and sedimentation rate. We will start simple and work toward more
complicated scenarios. Give me complete answers that make all the logic connections.
Hint: After you have maximized the 2-D window, you can make a “screen shot” of the image by:
 Simultaneously holding down the “Shift - 4” keys.
 Hold-clicking from the upper left corner to the lower right corner of the 2-D window.
 Double click on the Picture file you created on the desktop.
Hint: Always look over the questions before starting a simulation. This way, you will have to rerun it fewer times.
Hint: You can rerun the simulation by selecting Reset, then Start in the Simulation window.
SIMULATION ONE:

From the FILE Menu, OPEN PROJ_B&Cstartup

Maximize the 2-D window; minimize the 3-D window
The horizontal distance in the 2-D profile is 80 km; each tick mark is 4000 m. The Y-axis is water depth,
so elevation above average sea level is a minus number, and depths below are positive. The program
generally starts sea level half way up the rise (this is set at 0), so that the highstand is at –50m and the
lowstand is at +50m. I have set the time lines at each 25,000 years so they can be used to track where
you are in the simulation.
1. In the Simulation window, click Start. Watch the sea-level line (blue) and the time counter (top
right). On the graph provided below, sketch the sea-level curve, indicating the time of start and finish,
as well the timing and elevation of the highstands and lowstands. (5 pt)
2. The diagram above is taken directly from the screen at the end of the simulation (refer to it for
details). On the diagram above, highlight the time lines for segments when sea level has dropped in
red (these are called “offlaps”); highlight time lines associated with rising sea level in blue (these are
called “onlaps”). (5 pts)
3. On the above diagram, I have highlighted some other important features. Line X traces one of the
dashed lines on the model output. What do these dashed lines represent? Be as complete in your
explanation as possible. The dashed lines represent the sediment surface every 25,000 years (time
lines – 5 pt).
4. What specifically does the dashed line that is highlighted by the bold black line (X) represent? This is
the highstand surface as the first sea-level cycle reaches –50m. (note: the next two time lines
represent falling sea level) (5 pt)
5. Remember that the model plots sediment types within specific cells, each representing 4 km of
distance. As a result, the boundaries are a bit jagged, so you have to draw smoothed lines to better
approximate what sedimentary boundaries look like. In this model, what do the red and yellow areas
represent (package A - consider sediment type, facies, location, etc.)? These are sandy sediment (2
pt) associated with the prograding delta facies (2 pt) close to shore (1 pt extra)
6. How about the various greens (package B)? These are finer sands (2 pt) in front of the delta (the
nearshore zone – 2 pt).
7. And, the blues (package C)? Muds (2 pt) in the deeper offshore (2 pt)
In the Parameters window, go to Set Model Parameters and change the run TIME to 128,000 years.
In the Simulation window, Reset the simulation. Start the simulation and let it run. It will stop just
after the second highstand and will plot a time line for 125,000 years.
8. Is the time line the same thing as a facies boundary? NO (2 pt)
9. Why are they not coincidental? Because a time line is the sediment surface at one point in time. It,
therefore, crosses environmental boundaries (and, therefore, facies – 5 pt)
In the Parameters window, go to Set Model Parameters and change the run TIME back to 225,000
years, Reset and Start the simulation. Watch the surface along the time line as sea level falls and comes
back up. You ran recreate this by rerunning the simulation and stopping it manually (click on the screen)
just after the second sea-level maximum. In this case, however, you will probably get a stick diagram
showing only the time lines until you start the last part of the simulation. If you are having difficulty
seeing things, then go back and change the TIME to 128,000, rerun, set to 225,000 and finish.
10. What happens to the time line as the shelf is exposed? The time line gets eroded (2 pt)
11. Why is this not uniform along the exposed surface? Because the “shallower end” of the shelf
surface is exposed first as sea level drops and flooded last as it rises. As a result, erosion has
more time to work at the shallower end.... and erosion is greater. In essence, erosion is a “pie
slice” with the point at the lowest extreme of the sea-level drop (i.e., almost no exposure time
and, therefore, little to no erosion. (5 pt)
12. The surface that you are left with at the lowstand is the flooding surface. How does it relate to the
time lines and facies boundaries? It doesn’t relate to either. It is the resulting surface after all
that erosion. Again, because the upper reaches of the surface are flooded later, it will be more
eroded before it is covered by sea water and deposition cranks up again. (5 pt)
13. So, how do you find the flooding surface in the simulation? It is the surface across which the
sequence deepens upward. (Note that this is easiest to find where we have deeper offshore muds
laid down after rapid transgression sitting directly on top of delta deposits near the lower end of
the sequence. It is harder to find near the highstands and lowstands as you end up with sand on
sand.) (5 pt)
14. How about in the field? Same thing. Look for deep offshore muds sitting on top of sands. (2 pt)
15. Are the parasequences in this simulation a) prograding, b) aggrading or c) retrogradational? Explain
why. Prograding (2 pt) Because sea level returns to the same elevation and there is some of the
last parasequence left, the new highstand shoreline is seaward of it’s last position. Also, the
next downlap sits on (and in front of) the previous one (5 pt).
SIMULATION TWO:
 In the File menu,
PROJ_B&C SlopeA
OPEN
project
 Reset and Start the simulation
In this simulation, we have increased the
scale of the offshore slope to 240 km. We
again have a gradual and gentle slope, but
the sea level history is more complex. A
series of nine 100,000-yuear first-order
cycles (i.e., Melankovich cycles) are
superimposed on a longer (ca 900,000
years), second-order seal-level cycle. The
model has run for the same 225,000 years as
in the last case.
You should notice that each parasequence has two packages of coarse sediment, one near the
highstand and the other near the lowstand. Each is associated with outbuilding as the rate of sealevel change slows.
1. What differences do you see in the overall slopes of the highstand vs lowstand packages?
What is responsible for the difference? The lowstand packages have higher slopes than the
highstand ones (2 pt) because they are moving down over the edge of the previous
shelf.(2 pt)
2. How has the spatial relationship between the first three coarse depositional packages in this
scenario changed relative to the last simulation? What is responsible for these differences?
They are still prograding, but they are also getting higher (3 pt) Maximum sea level is
higher for each succeeding first-order cycle (5 pt).
3. Compare the three prograding parasequences in the model to the ones in Figure 2. What is
different between the two (hint: look at the landward and seaward ends of the packages).
What is responsible for the two differences. Remember: The LSST tract ends when the
parasequences are no longer progradational. The seaward ends are pretty similar, but the
landward end in this simulation are moving upslope instead of out (Note: this is an
artifact caused by the model not allowing sedimentation above sea level; we’ve done this to
make things a little simpler for you. In real life, we’d probably see something that looks
more like Figure 2) – 2 pt

Go into Set Model Parameters in the Parameters menu. Change Simulation Time to
900,000 years.

Start the simulation. Because all you have done is to increase the total run time of the
simulation, it will continue from where it left off (unless you have already reset it). The end
result should look like the figure on the top of the next page. Remember that this cross
section is vertically exaggerated over 5,000 times. In actuality, it looks more like the second
cross section beneath it, which is exaggerated only 10 times.
1. Outline and number each parasequence on the upper diagram above, using the numbers on the
SL curve the provided on the previous page. Please a color (other than red) that stands out.
Make sure you have it right before you start marking. Remember, each parasequence is
bounded by two flooding surfaces. (5 pt)
2. Using a red pencil, trace the Maximum Flooding Surface. It’s the one separating the TST
and the HSST. (5 pt)
3. Using other colors, outline the LSST, TST and HSST. Review your answer to Q2 on p.9
before deciding where the LSST ends. 5 pt each
4. Describe or mark where the best oil reservoirs would occur in this scenario. Explain why. The
best reservoirs will be in the progradational packages that are covered by muds (traps).
(3 pt)
5. During the generation of the last few parasequences, sandy (red) layers start forming near the
base on the seaward slope (starting around 690,000 years). What is going on? You may have
to rerun the simulation to watch for this. The slope is failing and forming turbidites (3 pt)
6. How might this relate to the evolution of passive margins like Atlantic North America? Over
time, intense sedimentation forms a shelf-like profile. (3 pt)
SIMULATION THREE:
Let’s try a last model that uses an Atlantic type passive margin similar to the one we were left
with at the completion of the last simulation.

In the File menu, Load PROJ_B&C Atlantic

Run the simulation
After the model runs for its complete 300,000 years, the output should look something like this
once you maximize the 2-D window. As before, it starts with three progradational parasequences
and then starts to “walk up” the slope as the rate of second-order sea-level rise quickens. The
TSST starts after the second parasequence is completed. Did you get this right in Q3 on page 10?
I did – wow!!

Reset the Simulation; In the Parameters menu, open the Set Model Parameters window.

Double the sedimentation rate by changing the Terr. Input (av. m/yr) (right half) from
0.001000 to 0.002000.

Start the model; it will run for 300,000 years again
What changes do you notice on the final output compared to the profile above? What is
responsible? Be a complete in your answer as possible. The sediment packages are thicker (2
pt) and prograde further seaward (2 pt). More (2 pt) and coarser (2 pt) sediment is making
it into the basin, The higher sedimentation is filling up the accommodation space faster (2
pt) and starting seaward progradation faster (2 pt) max or 8 points.
Now:
 Reset the simulation
 Go into Set Model Parameters in the Parameters menu.
 Return the Terr. Input (av. m/yr) to 0.001000
 Change Simulation Time to 900,000 years.
 Start the simulation again; as it runs, watch for the Maximum Flooding Surface.
 When it is complete, do not reset the simulation unless you want to see it again to answer a
question. You will be extending its duration.
The completed simulation should look like the above cross section.
1. Using a red pencil, highlight the Maximum Flooding Surface. 5 pt
2. What happens to basin sedimentation after the third parasequence is deposited? Why? It gets
finer (2 pt) and slows way down (2 pt) because coarser seds are being trapped back on
the shelf (2 pt)
3. What happens between the 5th and 6th sequence? We start to drop sea level (second order)
and we dump all the seds into the basin. (3 pt)
4. When does rapid sedimentation return to the basin? As soon as the deltas can prograde to a
point near the shelf break (3 pt)
5. How is it different from the first episode of basin sedimentation during the initial 300,000
years? Coarser and faster/thicker (3 pt) Why? Because the delta had prograded much
closer to the shelf edge and more coarse sediment is dumped directly into the basin (3 pt)
6. How would this pattern change if this were the Pacific margin of the US? We would
probably see constant shallow sedimentation in the basin. (3 pt)
Go into the Model Control Panel and change the simulation duration to 1,600,000 years. Start
the simulation after looking at the following questions. BY not resetting the simulation, you can
restart it at 900,000 years. If you have any doubt about the folloiwing questions, reset the
simulation and start it at T=0. The simulation will slow down toward the end, but watch it
carefully, keeping the following in mind.
1. What is happening on top of the shelf throughout the last half of the first second-order cycle
and much of the second? It is eroding away (4 pt)
2. What is the relationship between the 5th parasequence and the 6th. How has the answer to this
question changed from that of question 3 on the previous page? What is going on? The fifth
cycle is part of the first 900,000-year cycle of sea-level rise, whereas the sixth is
associated with the second cycle (there is a MAJOR unconformity between them) 10 pt.
Before you hand this in, discuss it with your classmates and think about how this would
relate to the rocks if you were looking for these sequences in the field.