Abstract
The relationship between the magnetization and temperature in a high constant magnetic field for a temperature range between 5 K and 1100 K was examined for Apollo 11, 12 and 14 lunar materials. The average value of Curie point temperature is (768.2 ± 3.5)°C for the lunar igneous rocks and (762.5 ± 3.4)°C for the lunar fines and breccias. A tentative conclusion about the ferromagnetic substance in the lunar materials would be that Fe is absolutely dominant with a slight association of Ni and Co, and probably Si also, in the lunar native irons.
The antiferromagnetic phase of ilmenite and the paramagnetic phase of pyroxenes are considerably abundant in all lunar materials. However, a discrepancy of observed magnetization from a simulated value based on known magnetic elements for the temperature range between 10 and 40 K suggests that pyroxene phase represented by (M x Fe1-x ) SiO3 (whereM = Ca2+, Mg2+, etc and 0 ≤x ≤1/4) also may behave antiferromagnetically.
Magnetic hysteresis curves are obtained at 5 K and 300 K, and the viscous magnetic properties also are examined for a number of lunar materials. The superparamagnetically viscous magnetization has been experimentally proven as due to fine grains of metallic iron less than 200 Å in mean diameter. The viscous magnetization is dominant in the lunar fines and breccias which is classified into Type II, while it is much smaller than the stable magnetic component in lunar igneous rocks (Type I). The superparamagnetically fine particles of metallic iron are mostly blocked at 5 K in temperature; thus coercive force (H c ) and saturation remanent magnetization (I R ) become much large at 5 K as compared with the corresponding values at 300 K.
Strongly impact-metamorphosed parts of lunar breccias have an extremely stable NRM which could be attributed to TRM. NRM of the lunar igneous rocks and majority of breccias (or clastic rocks) are intermediately stable, but their stability is considerably higher than that of IRM of the same intensity. This result may imply that some mechanism which causes an appreciable magnitude of NRM and the higher stability, such as the shock effect, may take place on the lunar surface in addition to TRM mechanism for special cases.
A particular igneous rock (Sample 14053) is found to have an unusually strong magnetism owing to a high content of metallic iron (about 1 weight percent), and its NRM amounts to 2 × 10−3 emu/g. The abundance of such highly magnetic rocks is not known as yet but it seems that the observed magnetic anomalies on the lunar surface could be related to such highly magnetized rock masses.
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References
Bozorth, R. M.: 1951,Ferromagnetism, Van Nostrand, pp. 1–968.
Doell, R. R., Grommé, C. S., Thorpe, A. N., and Senftle, F. E.: 1970,Proc. Apollo 11 Lunar Sci. Conf., Vol.3, pp. 2097–2102.
Dyal, P., Parkin, C. W., Sonett, C. P., DuBois, R. L., and Simmons, G.: 1971, Apollo 14 Prelim. Sci. Rep., NASA SP-272, pp. 227–237.
Gaunt, P.: 1960,Phil. Mag. 8, 1127–1148.
Grommé, C. S. and Doell, R. R.: 1971,Proc. Second Lunar Sci. Conf., Vol.3, pp. 2491–2499.
Hargraves, R. B. and Dorety, N.: 1971,Proc. Second Lunar Sci. Conf., Vol.3, pp. 2477–2483.
Helsley, C. E.: 1970,Proc. Apollo 11 Lunar Sci. Conf., Vol.3, pp. 2213–2220.
Ishikawa, Y. and Akimoto, S.: 1958,J. Phys. Soc. Japan 13, 1298–1310.
Larochelle, A. and Schwarz, E. J.: 1970,Proc. Apollo 11 Lunar Sci. Conf., Vol.3, pp. 2305–2308.
Levinson, A. A. and Taylor, S. R.: 1971,Moon Rocks and Minerals, Pergamon Press, New York, pp. 1–222.
Mason, B. and Melson, W. G.: 1970,The Lunar Rocks, Wiley-Interscience, New York, pp. 1–129.
Nagata, T., Ishikawa, Y., Kinoshita, H., Kono, M., Syono, Y., and Fisher, R. M.: 1970,Proc. Apollo 11 Lunar Sci. Conf. Geochim. Cosmochim. Acta Suppl. 1, Vol.3, pp. 2325–2340.
Nagata, T., Fisher, R. M., Schwerer, F. C., Fuller, M. D., and Dunn, J. R.: 1971,Proc. Second Lunar Sci. Conf., Vol.3, pp. 2461–2476.
Néel, L.: 1949,Ann. Géophys. 5, 99–136.
Runcorn, S. K., Collinson, D. W., O'Reilly, W., Battey, M. H., Stephenson, A., Jones, J. M., Mauson, A. J., and Readman, P. W.: 1971,Proc. Apollo 11 Lunar Sci. Conf., Vol.3, pp. 2364–2388.
Runcorn, S. K., Collinson, D. W., O'Reilly, W., Stephenson, A., Greenwood, N. N., and Battey, M. H.: 1971,Second Lunar Science Conference (Unpublished proceedings).
Sawaoka, A., Miyahara, S., and Akimoto, S.: 1968,J. Phys. Soc. Japan 25, 1253–1257.
Shenoy, G. K., Kalvius, G. M., and Hafner, S. S.: 1969,J. Appl. Phys. 40, 1314–1316.
Schwarz, E. J.: 1970,Proc. Apollo 11 Lunar Sci. Conf., Vol.3, pp. 2389–2398.
Strangway, D. W., Larsen, E. E., and Pearce, G. W.: 1970,Proc. Apollo 11 Lunar Sci. Conf. Vol.3, pp. 2435–2452.
Swann, G. A., Bailey, N. G., Bastan, R. M., Eggelton, R. E., Hait, M. H., Holt, H. E., Larson, K. B., McEwen, M. C., Mitchell, E. D., Schaber, G. G., Schafer, G. P., Shepard, A. B., Sutton, R. L., Trask, N. J., Ulrich, G. E., Wilshire, H. G., and Wolfe, E. W.: 1971, ‘Preliminary Geologic Investigations of the Apollo 14 Landing Site’, Apollo 14 Prelim. Sci. Rep., NASA SP-272, pp. 39–85.
Wasilewski, P. J.: 1969, ‘Correspondence Between Magnetic and Textural Changes in Titanomagnetites in Basaltic Rocks’, D.Sc. Thesis, Univ. of Tokyo, Fac. Sci.
Wohlfarth, E. P.: 1963, ‘Permanent Magnetic Materials’, inMagnetism, Vol.3 (ed. G. T. Rado and H. Suhl), Acad. Press, New York, pp. 351–393.
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Nagata, T., Fisher, R.M. & Schwerer, F.C. Lunar rock magnetism. The Moon 4, 160–186 (1972). https://doi.org/10.1007/BF00562924
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DOI: https://doi.org/10.1007/BF00562924