Hi RAZD,
Since you were nice enough to actually read and think about my post to you last January on Gilbert Deltas. I thought I’d pass the following information along to you.
I’m hoping you take the time to look at it and think about it and expand your understanding of geology, something a lot of people on this site could use.
The Gilbert Delta is fairly simple, and I saw that you did understand what I told you about it.
Now I want to explore Sequence Stratigraphy. I want to look at depositional environments as they progress through time and how deposition and formations actually occur in the real world.
Let’s look at the Book Cliffs just north of Grand Junction Colorado and extending west into Utah.
This is a movie of the deposition, and I want you to look at it, and then go through it step by step, you can do that with the arrow on the right tool bar.
Think about the formations (a mapable unit), how they are formed, and how you see them today.
The movies here are easy to understand, at least for me, I’ve been making movies in my mind like this for 35 years. Taking the actual vertical information from well logs, drill cuttings, cores or seismic data is another ,perhaps, somewhat more difficult way to make this movie. It is how I make my living and find unknown and undiscovered oil and gas deposits.
Here is movie 1 of the Book Cliffs, watch it a few times and then go through it step by step and pay attention to what sea level is doing at any given time and the resulting deposition OR erosion.
Note that each step shows you a time line, and that formations are being deposited at the same time, not like the layer cake geology of 200 years ago.
http://sepmstrata.org/movies/CLASTICSYSTEMTRACTS.MOV
So you do see how formations are NOT deposited first one and then another, but are interrelated. As you go through step by step think of the different ecosystems, and that that is where you will find various fossils. You won’t find land dinosaurs in deep water deposits or marine fossils in land/fluvial deposits.
Fossils change from the Cambrian to the present but they also change laterally and occur in their appropriate depositional environment.
Note that what you see in the rocks vertically occurred horizontally at the same time.
There are also changes in the mineralogy and organic material as you move from the eroding mountains toward the seashore.
Here is movie 2, note the uplift, mountain building that occurs later in the video. The mountains are not shown off to the right but you can see their influence on the deposition and the resulting structure.
http://sepmstrata.org/movies/TwoSidedGif2.mov
Movie 3 shows how you use well log data to create a Stratigraphic Sequence and movie 4 uses seismic data to show the same.
http://sepmstrata.org/movies/INCISED-VALLEY.MOV
http://sepmstrata.org/movies/ChronoMovie.mov
There is a lot of information in these movies, if you or anyone else has a question, please feel free to ask.
More information can be found here:
The modules below are tied to lectures, movies and exercises that can be accessed from this web site and used for academic and educational purposes. They have been organized so the user can start with little understanding of sequence stratigraphy but through systematically following the modules in order can improve vocabulary, understanding and experience. Initial materials and exercises are introductory in character but as one moves through the modules, their materials become more sophisticated and challenging. Once the modules have been completed you should have a good understanding of sequence stratigraphy and should be able to use well, seismic and outcrop data to make mature interpretations of the sedimentary sections you might study. An additional intent of the web site is that it becomes a ready reference to the complex world of sequence stratigraphy!!
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