Unless you’re a keen follower of the latest petroleum news, you probably missed an interesting story published late last year. An oil find in the Flemish Pass region of offshore Newfoundland had, it was claimed, led various companies to start searching the Atlantic coast of Morocco.
This might sound pretty odd. How could a discovery beneath the seafloor of Atlantic Canada enable prospectors to locate oil in North Africa?
As regular readers of this column might suspect, the answer is tectonic. Newfoundland and Morocco might be a long way apart today, but for a significant chunk of the last half-billion years, they were near-neighbours. In the hunt for black gold we just have to do a bit of transatlantic time travel.
An Atlas of Avalon
To undertake this voyage, we must cross the ocean of Atlas. Sail more than 2,500 miles, land on the Moroccan coast, start walking east and you’ll soon be in the foothills of his mountains, the mythical end of the world. Before you hit the peaks, though, you’ll find yourself traversing a slice of terrain that – though generally hot and dry rather than foggy and drizzly – is actually of homely origins.
In the early 1980s, geological research showed that the Moroccan Meseta, the flat, high plains between the Atlantic coast and the Atlas Mountains, was formed of rocks of the same age and geological structure as much of eastern North America.
Crucially, the Moroccan strata also yielded the same fossils. In particular, they contained the large, distinctive trilobite Paradoxides. So named because the scientists who first found it thought it a ‘paradoxical stone insect’, this ancient arthropod crawled the seabeds in the middle of the Cambrian period, around 510 million years ago.
Found famously in Wales and then Newfoundland, Paradoxides has an odd but telling distribution. (It has even proven the inspiration for a book by award-winning, St John’s-based poet Don McKay.) It also occurs in New Brunswick and Nova Scotia, Maine and Massachusetts, Scandinavia, Spain and Morocco. When combined with other fossils, the co-occurring rock types, and the pattern of faults and fractures, its presence shows that these disparate locations were once united.
As a consequence, an ancient chunk of the Earth’s crust could be reconstructed. In recognition of the diagnostic fossils and geology of eastern Newfoundland, this long-lost micro-continent was dubbed Avalonia.
That Old Lost Sea again
As I’ve mentioned before, in a tale of Gros Morne’s geology, the Atlantic Ocean had a precursor. Named in honour of Atlas’ father, this sea was the Iapetus, and it existed between about 600 and 400 million years ago.
At the opening of Iapetus, Avalonia was located on the eastern side of the ocean, on the edge of the European-African landmass, Gondwana. However, after a hundred million years or so, it broke free from its moorings like a poorly captained cruise ship, and began drifting towards proto-North America, properly known as Laurentia.
As Avalonia advanced westward to dock with this brave new world, another body of water opened up behind it. The Rheic Ocean honours Iapetus’ sister, Rhea. As her brother’s sea began to close, so Rhea’s expanded, but by the time Avalonia collided with Laurentia even the Rheic days were numbered. The Earth’s continents were heading for collision course, and in the late part of the Palaeozoic era, they began smashing together.
Rise and Fall of a Supercontinent
By about 300 million years ago, they had fused into the supercontinent Pangaea. Yet that tiny fragment – Avalonia – was still there at the heart of it, hugging the giants together; Newfoundland and Nova Scotia embracing North Africa.
So it remained for another 100 million years, but all good unions eventually come to an end. In the first period of the Mesozoic era, the Triassic, Pangaea became unstable and began to start rifting apart. Enormous volcanoes set up camp, literally, forming the Central Atlantic Magmatic Province between Nova Scotia and North Africa.
The vast plateaux of basalt that welled up were geologically short-lived, with four pulses spread out over half-a-million years or so, but they represented the birth of the Atlantic. Once the Earth’s crust had begun to pull apart sufficiently, the fissures became basins, and water started accumulating within them. From tiny lakes do giant oceans grow.
The oily ocean
After all that scene-setting, you’re probably still wondering what this has to do with prospecting for oil. Well, as the Atlantic continued opening in the Jurassic, so the rift basins got bigger, the sea-levels got higher, and the ingredients for a petroleum system – organic-rich muds as a source of oil, permeable sands as a reservoir – were produced.
An understanding of this geology has arisen from the drilling that has taken place over the last 20 years, in regions such as the Grand Banks, NL, and Sable Island, NS. Much is still unknown, but companies have realized that its Jurassic proximity to North America could mean that North Africa has similar prospectivity. Offshore Morocco has undergone very little exploration, but that might change.
It may prove after all that Newfoundland is not the key region. Petroleum geologists think that the Scotian Basin is more directly relevant to an understanding of the North African Atlantic.
Whatever transpires, for an exotic holiday there are few cities more beguiling than Marrakech, the old capital of Morocco. In the souks of its medina, a UNESCO World Heritage site, you’ll find a multitude of stalls, many of which sell fossils. Keep an eye out for the beautiful local specimens of Paradoxides. You might just be able to bring a transatlantic time-traveller home with you.