Magnetic effects associated with chemical changes in igneous rocks |
| |
| Authors: | Ronald T Merrill |
| |
| Institution: | 1. Geophysics Program and Department of Oceanography, University of Washington, 98195, Seattle, Wash., USA
|
| |
| Abstract: | Experimental evidence and theory indicate that chemical changes occur in many igneous rocks at sufficiently low temperatures to significantly affect the remanent magnetization. Some chemical changes lead to self-reversals of magnetization that are not reproducible in laboratory experiments. Such self-reversals appear to be very rare in subaerially-erupted basalts, but they probably are much more common in some other rock types, such as granites and diorites. The stability of the natural remanent magnetization in igneous rocks can be decreased, left unaltered, or increased by chemical changes. In addition, chemical changes will usually affect the intensity of magnetization in a rock; the intensity can increase, decrease, or (rarely) be left unaltered by a chemical change. Such changes are important to consider in the development of improved techniques for obtaining reliable estimates of the intensity of the Earth's magnetic field in the past and in correctly interpreting marine magnetic anomalies. Finally, experiments and theory are presented which suggest that many of the chemical changes in igneous rocks will only occasionally produce significant changes in the direction of the magnetization. |
| |
| Keywords: | |
| 本文献已被 SpringerLink 等数据库收录！ |
|
