- So here are the main types of source rocks and their typicaldepositional environments. This is just a cross-cut across continents going to oceans and thenup onto another side. So you can pretend this would be Brazil and then this would be off theSahara on the African side. There are different types of source rock. Here we have settings A,which has high wax, oil prone. This is an interiorbasin, lacustrine system, or it could be an inland sea environment. Usually lacustrine, highwax, oil prone material. These can desiccate like theDead Sea or the Salton Sea. And the bacteria and algae build up wax layers to preserve themselves when the sea bed goes dry. On the land, you don'tget good source rock, non-source rock. Offshore, in the Delta system, you may get a type 3 material, which tends to be the leafymaterial, woody materials, not the dense swamps thatyou get for coal deposits, but deposition of leafymaterial, woody material that's more gas prone. And then offshore, you have biologicalphytoplanktonic blooms. Those will sink to the bottom. If you can develop an anoxic layer, due to minimized ocean circulation, then you will preservethat organic matter, and you can get source rocks with total organic carboncontents greater than 3%. And these types of source rocks in the oil geochemistry world are called Type 1 for the lacustrine, type 2 for the main oceanographicocean phytoplankton, and Type 3 is swampmaterial that's made it out into the marine environment. So, an example of a present day situation, where you're devlopinga huge source rock area that would be good for your great-great-great-great-greatgrandchildren several millions of years from now, is in the Black Sea. As you can tell, asyou know, it's isolated from the main thermohalineocean circulation. It's a semi-enclosed basin with a very shallow outflow sail, less than 200 meters deep, and high biological productivity. And about 200 meters downfrom the surface waters, the waters are anoxic, full of sulfides, and the bottom sediments are black sludge, very rich in organic matter. So that's an example ofa modern day accumulation that will be a great source rock area for future generations. So let's look at the past. And here's an example of the split of the Atlantic Ocean, as we go from the Albian through to the Campanian Maastrichtian. And remember, as we talked about, you need connection withthe Antarctic system, or the deep ocean poles. The Arctic Ocean does not develop that deep system, the Antarctic does. And so, on the early splittingphase of the Atlantic, you did not have bottom water circulation. So you would tend todevelop minimal circulation, close circulation that could have rich source rocks forming. And in addition, in anothertalk, you'd also learn about the sediment, the reservoir material sediments that are coming inin this type of situation. So as the rifting continues,you start opening up this seaway to the northwhere there's not a lot of bottom water circulation coming in. And in the central part, you still have fairly closed basin and some anoxia. Once you start breaking through, separating far enough, you can start developing circulationall the way through. And by the Campanian Maastrichtian time, you have connected the Atlantic system with the Antarcticoxygen bottom water pump. So then you will be stopping the preservation and creation of anoxia in the bottom waters. So if you're lookingin an expiration sense, if you're looking for areas where there'd be source rock, the Albian could haveexcellent source rocks, the internal basin, lucustrine systems. You could still have very good marine systems, still have anoxia. It starts to dwindle,and by the time you reach Campanian Maastrichtian, you may not have any good source rocks devleoping. So in your depositional modeling system for your exploration, you'd be looking for source rocks in these earlier times.