![Geological Survey of Canada Geological Survey of Canada](/web/20061103045023im_/http://www.gsc.nrcan.gc.ca/esst_images/gsc_e.jpeg) Natural Resources Canada > Earth Sciences Sector > Geological Survey of Canada > Past lives: Chronicles of Canadian Paleontology
Past lives: Chronicles of Canadian Paleontology Redwater and Ed Klovan
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
![Section of core from the Upper Devonian Redwater Reef. University of Alberta Collections. (Photo by BDEC (c).) Section of core from the Upper Devonian Redwater Reef. University of Alberta Collections. (Photo by BDEC (c).)](/web/20061103045023im_/http://www.gsc.nrcan.gc.ca/paleochron/images/core2_1.jpg) Section of core from the Upper Devonian Redwater Reef. University of Alberta Collections.
(Photo by BDEC (c).) |
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. |
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