RUSSIAN JOURNAL OF EARTH SCIENCES VOL. 7, ES3003, doi:10.2205/2005ES000175, 2005
[26] It is possible that a change in the magnitude of the regular variations of the field direction is a seeming effect. The angular elements of the geomagnetic field vector, Dec. and Inc., are calculated using their X, Y, and Z components. It is obvious that under the conditions of the low medium field intensity, the same increments of these components lead to a greater change in the angular elements compared to the case of high field intensity.
[27] According to the modern views, the main variation spectrum is a principally important characteristics of a dynamo mechanism. The periods of the variations included into the main spectrum (archaeomagnetic data) correspond to the periods of MAC waves in terms of their theoretical estimates [Braginskii, 1974]. MAC waves are an integral part of the generation mechanism being the manifestation of its principal instability. It is a change in the MAC wave spectrum, that is, in the periods of secular variations, that record variations in the dynamo process.
[28] The identification of the main-spectrum variations with the MAC waves is based not only on the proximity of their theoretical and experimental periods, but also on some specific variations of the basic spectrum variations stemming from the results of arhaeomagnetic investigations. First, the main-spectrum variations have a running and a standing component, both being pertinent to MAC waves. Secondly, some variations, like, for example, the well-known variation with a period of 1200 years, show distinct global features [Burlatskaya, 1999].
[29] The secular variations recorded during polarity reversals were studied using the Gauss-Matuyama, Matuyama-Jaramillo and Matuyama-Brunhes reversals [Petrova et al., 1980, 1992]. These authors came to the conclusion that the secular variation spectrum had not varied throughout the inversion process. Moreover, the comparison of their results with the data reported by Gurarii et al. [1994] suggested the conclusion that the basic spectrum of the geomagnetic field variation had not changed during the last 5.5 million years, that is, the dynamo mechanism operated continuously.
![]() |
Figure 4 |
[31] These results do not contradict the view proposed by Braginskii [1974], yet, can be treated as another indication of the permanent instability of the generation mechanism, the extreme manifestation of which is the geomagnetic field reversal.
[32] Therefore, the sole, most substantiated, conclusion that can be offered at the present time is that the study of this problem need be continued.
Citation: 2005), Geomagnetic field reversals: Main results and basic problems, Russ. J. Earth Sci., 7, ES3003, doi:10.2205/2005ES000175.
Copyright 2005 by the Russian Journal of Earth Sciences (Powered by TeXWeb (Win32, v.2.0).