An Anomaly in Geomagnetic Variations at Mould Bay in the Arctic Archipelago of Canada
Standard-run magnetograms obtained from Mould Bay, Prince Patrick Island, demonstrate a striking absence of vertical magnetic field variations corresponding to an anomalous steepening of the vertical field power spectrum. Assuming the presence of a sheet conductor at depth, it is estimated from the...
| Published in: | Geophysical Journal International |
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| Main Author: | |
| Format: | Text |
| Language: | English |
| Published: |
Oxford University Press
1963
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| Subjects: | |
| Online Access: | http://gji.oxfordjournals.org/cgi/content/short/8/1/26 https://doi.org/10.1111/j.1365-246X.1963.tb02897.x |
| Summary: | Standard-run magnetograms obtained from Mould Bay, Prince Patrick Island, demonstrate a striking absence of vertical magnetic field variations corresponding to an anomalous steepening of the vertical field power spectrum. Assuming the presence of a sheet conductor at depth, it is estimated from the frequency dependence of the spectrum that a 20 km thick layer with a conductivity about 10−11 e.m.u. is required near the bottom of the crust. There appears to be no evidence for such a highly conducting crust. Anomalous temperatures difficult to reconcile with a stable region are required to explain the anomaly by semiconduction processes. The extent of the Mould Bay anomaly is as yet unexplored. Russian results (Zhigalov 1960), and a search of Arctic magnetograms available here, show that severe attenuation of the vertical field fluctuations occurs over the deep ocean basins. It is concluded that the magnitude of the attenuation found on drifting stations can be explained by the presence of the conducting ocean, with reasonable estimates of the wavelength of the inducing field. However, it appears unlikely that the Mould Bay results can be so explained. |
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