Oil From Ancient Seas: Where Ahoy?

Oil was formed in warm, ancient seas, from microscopic organisms which thrived in a high CO2 environment. The first photosynthetic micro-organisms evolved around 3.5 billion years ago, which provides a great deal of time for hydrocarbon formation through the eons. Modern oil companies are scooping up the most recently formed crude oil, from deposits formed just a few dozens or hundreds of millions of years ago -- from the ancient sea-beds and former sea-beds which were easy to locate. But where will we find the multi-billion year ancient seabeds -- the really big oil fields? It will require a great deal of patience, detective work, and advanced technological tools -- some of which have not been invented yet.

If you want to go prospecting in history for likely locations of super-giant oil deposits, look for the ancient sea-beds. The Wikipedia reconstruction of Earth's tectonic history should give you a rough idea of where the ancient seas may have been. The YouTube video below provides another look at the dynamic ballet of continents and plates. Pay careful attention, insert a bit of creative extrapolation and interpolation, and draw your own conclusions.

If you look down below at the Wikipedia clock representation of Earth's time scale -- far back into the pink -- you will see where photosynthesis begins, around 3.5 billion years ago. Then travel clockwise all the way through the pink and yellow to get to the blue and green, where the seabed locations of modern oil formation opened up to provide ideal environments for oil formation. What happened to all of the oil from the roughly 3 billion years between the start of photosynthesis and the generation of modern oil, originating from all of those wildly reproducing photosynthetic microbes?

If you watch the undulations of the tectonic plates, and the constantly opening and closing of sea basins over the 600 million years pictured in the YouTube video, you can see that the perfect windows for oil formation were constantly opening and closing. No sooner would a perfect warm sea open up for oil production, than the tectonic plates would shift and cover it up.

All the while massive vulcanisation was taking place within and around the sedimentary basins where rich oil deposits from past ancient seas were sitting in the boiling heat deep underground. What happened to all of those billions of years of deposits?

Some must have escaped as gas or volatile hydrocarbon, migrating to upper layers of the crust, or into the atmosphere. Some of the oil would have likewise found its way to upper layers of crust, trapped by impermeable layers -- or escaping as seeps to be metabolised by oil-munching microbes.

But some of it -- perhaps a huge part of it -- is still trapped beneath volcanic rock, beneath moving tectonic plates, beneath billions of years of sediment. Waiting for clever boys and girls to track it down.

More: Recent study of a massive rotational shift of the super-continent Gondwana approx. 525 mya

Growing awareness of rich variety of life beneath the seafloor

Deep open ocean most unexplored part of planet

It should be clear that since 70% of Earth is covered by ocean, most of the planet's treasure trove of petroleum and other fossil fuels is likely to lie beneath the seas. Both polar regions are relatively unexplored in terms of mineral wealth, but the same is true for the open oceans. Although it does not take a genius to suppose that large deposits of oil may lie in the Gulf of Mexico or under the ancient Tethys Sea, it may take a great deal of clever detective work to find earlier versions of these nutrient-fed warm water shallow seas -- and where the sediments may have migrated over the past hundreds of millions of years.