The presence of tropical reefs a mile beneath the frigid plains of central Alberta was an intriguing and lucrative novelty for petroleum geologists, but it was almost too preposterous for the general public to accept

Alberta became a "have" province at precisely 4:00 in the afternoon on February 13, 1947. That was when Imperial Leduc No. 1, spudded 25 km southwest of Edmonton, drilled into a Devonian oil-bearing carbonate mound at a depth of 1544 m. By the end of the year, with 30 wells producing 3,500 barrels of oil a day from similar mounds in central Alberta, the province had become one of the major oil producing regions in North America. These carbonate mounds, which were relatively straightforward to find with seismic techniques, originally consisted of limestone (calcium carbonate) which later had been altered to dolostone (calcium magnesium carbonate). The resulting recrystallization and volume decrease effectively obliterated the original texture of the limestone and any associated fossils. The nature of these mounds could not be determined, but Imperial Oil geologists suspected that they were tropical reefs of Late Devonian age (380 Ma).

In 1948 a large oil-bearing reef was discovered under the town of Redwater, but this reef consisted of original limestone, not dolostone. Drill cores of this reef might disclose evidence of its ancient ecology, but paleoecology was yet an unformed discipline and such work had to await another decade when an Albertan went to graduate school in New York City.

Ed Klovan grew up at Lake Wabamun outside Edmonton. After an undergraduate degree in geology from the University of Alberta, he began graduate work at New York's Columbia University in 1957. Columbia then was home to two of the brightest researchers in the fledgling field of paleoecology -- Norman Newell and John Imbrie, both of whom had a deep interest in modern reef ecology. Imbrie suggested to Klovan that he prepare a class seminar on the paleoecology of the Devonian reefs of central Alberta. By then hundreds of wells had been drilled into Leduc reefs, but Klovan's library research was stymied because virtually nothing had been published on their nature and paleoecology. In failing to find a seminar topic, he had identified a thesis topic.

Klovan decided to concentrate on the single, largest, well-drilled limestone reef -- Redwater -- and began to map the distribution of carbonate rock types and fossils in the 8 cm diameter core from 37 wells. Conspicuous fossils include massive, tabular and stick-like stromatoporoids, tabulate and rugose corals and algae, along with brachiopods, gastropods, bivalves. The enigmatic stromatoporoids of layered calcareous material were particularly important. They consist of labyrinthine intertwinings of platforms and pillars that has been described as "tabular corals with cancer". Klovan demonstrated that Redwater, like all modern hexacoral/algal reefs, is zoned in response to water depth and turbulence into an organic reef, fore reef and back reef.

Klovan successfully defended his thesis in the fall of 1963 and published it the following year. Perhaps the most important contribution of this paper was not the documentation of the distribution of the facies and fossils in this large Devonian reef, but rather the demonstration that it was possible to analyze the paleoecology of reefs in the subsurface by studying cores. The Redwater study was quickly followed by comparable studies of most of the Devonian limestone reefs in western Canada, surface as well as subsurface.

Further reading:

Klovan, J.E.
1964:  Facies analysis of the Redwater Reef Complex, Alberta. Bulletin of Canadian Petroleum Geology, vol. 12, p. 1-100.