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Science Frontiers ONLINE No. 48: Nov-Dec 1986 |
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Oil, oil: everywhere, every age
Geologists have discovered a major deposit of oil in Precambrian rocks in Australia's Northern Territory. Precambrian oil does exist elsewhere -- around the Great Lakes, Russia, etc. -- but the Australian deposits differ in that they are economically attractive. The oilbearing strata are dated at between 1.4 and 1.7 billion years; and the oil itself is at least this old. Significantly, the oil contains extremely small amounts of steranes, which are thought to be derived from advanced organisms, but there were plenty of chemicals typical of primitive bacteria. The mere existence of commercially exploitable deposits of Precambrian oil implies that, far from being devoid of life, the ancient earth was host to immense accumulations of bacteria and other simple organisms.
(Anonymous; "Ancient Oil in Australia: A New Bonanza?" New Scientist, p. 26, September 11, 1936.)
Comment. As discussed above this Australian oil might have been produced abiogenically.
The surface and near-surface Athabasca oil sands in western Canada constitute a well-known deposit of almost unbelievable size. Geologists have long speculated about where such an immense quantity of biological matter could have originated. (Few dare to suggest nonbiological origins!) Now, we learn that below the Cretaceous Athabasca oil sands lies a 70,000 square kilometer "carbonate triangle" estimated to contain about 2 x 1011 cubic meters (about 6 cubic kilometers) of bitumen. This bitumen is closely related chemically to the oil sands above it. A common origin seems likely.
(Hoffmann, C.F., and Strausz, O.P.; "Bitumen Accumulation in Grosmont Platform Complex, Upper Devonian, Alberta, Canada," American Association of Petroleum Geologists, Bulletin, 70:1113, 1986.)
Comment. Many geologists believe that these incredible accumulations of organic matter migrated from some distant source to their present location. But just where was this prodigious wellspring of biological activity?
Reference. Controversies regarding the origin of oil are covered in ESC13 in our catalog: Anomalies in Geology. This book is described here.