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Science Frontiers ONLINE No. 69: May-Jun 1990 |
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Deep-sixing another hypothesis?
T. Gold once said, "In choosing a hypothesis, there isn't any virtue in being timid." Neither have the Swedes been timid in following Gold's lead by drilling for natural gas in the granite of central Sweden. All the experts pre-dicted this quest would come to naught, because there are no source rocks in the area containing biological materials from which the gas could have been generated. But Gold does not believe that the methane in natural gas comes from buried organic debris. Rather, most methane is primordial and abiogenic, a legacy left deep in the earth's crust when our planet was formed.
The 72-kilometer-diameter Siljan Ring in central Sweden is generally believed to be of meteoric origin. The granite here has been shattered, perhaps to a depth of 40 kilometers. If Gold's hypo-thesis about the origin of methane is correct, methane might well be found seeping up through this wound in the earth's outer skin. Further, the shattered granite might prove to be a gigantic reservoir of valuable methane. The Swedes decided to drill.
After three years and the expendi-ture of $40 million, drilling at the Siljan Ring has been terminated. The drill penetrated to 6.8 kilometers before it got stuck. No significant methane had been found. The experts snickered!
But the story is not finished, at least as far as Gold is concerned. He maintains that the drilling stopped just short of an apparent reservoir at 7.2 kilometers (probably located by seismic methods). Another, deeper hole will vindicate him, he believes. After all, there are tantalizing hints:
- The drillers did find an assortment of hydrocarbons that could have been deposited by upward-seeping
methane. Skeptics say they are derived from the drilling fluids.
- Tons of micrometer-sized grains of magnetite were taken out of the hole. Gold opines that these grains were synthesized by bacteria subsisting upon seeping methane at a depth of 6 kilometers.
- Russian drillers on the Kola Peninsula report the existence of intriguing circulating fluids as far down as 12 kilometers.
Despite the problems and disappointments at the first hole, some Swedish investors seem ready to finance a second hole at the Siljan Ring.
(Kerr, Richard A.; "When a Radical Experiment Goes Bust," Science, 247:1177, 1990.)
Reference. To read more on primordial methane and the Siljan Ring, refer to ESC16 in our catalog: Anomalies in Geo logy. Ordering information here.