RE:It a pump and dump ! Oil is created from kerogen. Kerogen is created from organic matter. It doesn't care if that is single cell life, aquatic life, mammal, vertebrate.... anything. But it take a lot of organic mater to create an substantial amount of kerogen.... like 90 tons of organic matter for a gallon of "oil". The reason you see most petroleum systems after the Cambrian time is because that is when life evolved from single cell life. It wasn't until the Silurian era that land life started. Hence a more abundance of organic matter! Anything after the Silurian era has good potential for a petroleum system. The zones that have target with source rocks are in the Mississippian, penslvsnian, and Permian time zones. They will drill beyond that down to pre Cambrian for getting the lithographic mapping completed.