Characteristics of VRM in oceanic basalts

Main Article Content

W. Lowrie
D.V. Kent


Laboratory experiments, each lasting several weeks, have been conducted to establish the characteristics of viscous remanent magnetization (VRM) in oceanic basalts from many sites of the Deep Sea Drilling Program (DSDP). VRM is most pronounced in low-coercivity basalts whose natural remanences (NRM) have low median destructive fields, less than 100 Oe. A simple logarithmic acquisition law is rarely obeyed, but two or three distinct stages are instead observed, in each of which a logarithmic dependence of VRM intensity on acquisition time may be assumed. This observation leads to a simple interpretational model for the nature of VRM in DSDP basalts, but also implies that extrapolation of laboratory observations to geological times is not meaningful. Instead, the ratio of laboratory VRM (acquired in a 1 Oe field during 1000 h) to NRM is used as a minimum indicator of the potential seriousness of VRM. Experiments show that VRM acquired in the presence of NRM is more serious than VRM acquired in alternating field (AF) demagnetized samples. As most published VRM data in DSDP basalts were obtained after AF demagnetization, these are regarded also as minimum estimates of the significance of VRM acquired by oceanic basalts in situ. The consequences of the common occurrence of such an unstable component of magnetization in the oceanic basalt layer are considered in relation to the nature and distribution of oceanic magnetic quiet zones. The Cretaceous, and possibly the Jurassic, magnetic quiet zones are considered adequately explained by constant paleomagnetic field polarity. However, if VRM is a substantial and widespread magnetization component in the oceanic crust, it may not always be appropriate to interpret oceanic magnetic anomalies (or their absence) as an exact record of paleomagnetic field behavior. Remagnetization of the oceanic crust by VRM acquisition may be a viable alternative explanation of the origin of the marginal magnetic quiet zones.

Google Scholar           ARK:



Article Details

How to Cite
Lowrie, W., and D.V. Kent. 1977. “Characteristics of VRM in Oceanic Basalts”. Journal of Geophysics 44 (1), 297-315.
Bookmark and Share


Ade-Hall, J.M., Johnson, H.P. (1976) Review of magnetic properties of basalts and sediments, Leg 34. In: Yeats, R.S., Hart, S.R. (Eds.) Initial Reports of the Deep Sea Drilling Project, Volume XXXIV, pp. 769-778. Washington: U.S. Government Printing Office

Ade-Hall, J.M., Fink, I.C., Johnson, H.P. (1976) Petrography of opaque minerals, Leg34. In: Yeats, R.S., Hart, S.R. (Eds.) Initial Reports of the Deep Sea Drilling Project, Volume XXXIV, pp. 349-362. Washington: U.S. Government Printing Office

Atwater, T., Mudie, J.D. (1973) Detailed near-bottom study of the Gorda Rise. J. Geophys. Res. 78:8665-8689

Barrett, D.L., Keen, C.E. (1976) Mesozoic magnetic lineations, the magnetic quiet zone, and sea-floor spreading in the northwest Atlantic. J. Geophys. Res. 81:4875-4884

Cande, S.C., Kent, D.V. (1976) Constraints imposed by the shape of marine magnetic anomalies on the magnetic source. J. Geophys. Res. 81:4157-4162

Cande, S.C., LaBrecque, J.L., Larson, R.L. (1977) Marine magnetic anomaly data from the Jurassic and Cretaceous quiet zones: Implications for long period intensity variations of the paleomagnetic
field (abs.). EOS 58:740

Creer, K.M., Petersen, N., Petherbridge, J. (1970) Partial self-reversal of remanent magnetization and anisotropy of viscous magnetization in basalts. Geophys. J. Roy. Astron. Soc. 21:471-483

Dunlop, D.J. (1973) Theory of the magnetic viscosity of lunar and terrestrial rocks. Rev. Geophys. Space Phys. 11:855-901

Dunlop, D.J., Hale, C.J. (1977) Simulation of long-term changes in the magnetic signal of the oceanic crust. Can. J. Earth Sci. 14:716-744

Evans, M.E., Wayman, M.L. (1972) The mid-Atlantic Ridge near 45° N: XIX. An electron microscope investigation of the magnetic minerals in basalt samples. Can. J. Earth Sci. 9:671-678

Girdler, R.W. (1969) The Red Sea - a geophysical background. In: Degen, E.T., Ross, D.A. (Eds.) Hot brines and recent heavy metal deposits in the Red Sea, pp. 38-58. Springer, New York

Harrison, C.G.A. (1976) Magnetization of the oceanic crust. Geophys. J. Roy. Astron. Soc. 47:257-283

Hayes, D.E., Rabinowitz, P.D. (1975) Mesozoic magnetic lineations and the magnetic quiet zone off northwest Africa. Earth Planet. Sci. Lett. 28:105-115

Helsley, C.E., Steiner, M.C. (1968) Evidence for long intervals of normal polarity during the Cretaceous period. Earth Planet. Sci. Lett. 5:325-332

Irving, E. (1970) The mid-Atlantic ridge at 45° N: XIV. Oxidation and magnetic properties of basalt; review and discussion. Can. J. Earth. Sci. 7:1528-1538

Irving, E., Pullaiah, G. (1976) Reversals of the geomagnetic field, magnetostratigraphy, and relative magnitude of paleosecular variation in the Phanerozoic. Earth-Sci. Rev. 12:35-64

Kent, D.V., Lowrie, W. (1977) Magnetic properties of igneous rock samples from Leg 37. In: Aumento, F., Melson, W.G. (Eds.) Initial Reports of the Deep Sea Drilling Project, Vol. XXXVII (In press) Washington: U.S. Government Printing Office

Kent, D.V., Tsai, L.P. (1977) Paleomagnetism and rock magnetism of Upper Jurassic limestone and basalt from Site 367. In: Lancelot, Y., Seibold, E. (Eds.) Initial Reports of the Deep Sea Drilling Project, Vol. XXXXI (In press) Washington: U.S. Government Printing Office

Larson, R.L., Hilde, T.W.C. (1975) A revised time scale of magnetic reversals for the Early Cretaceous and Late Jurassic. J. Geophys. Res. 80:2586-2594

Larson, R.L., Pitman III, W.C. (1972) Worldwide correlation of Mesozoic magnetic anomalies, and its implications. Bull. Geol. Soc. Am. 83:3645-3662

Lowrie, W. (1973) Viscous remanent magnetization in oceanic basalts. Nature 243:27-30

Lowrie, W. (1974) Oceanic basalt magnetic properties and the Vine and Matthews hypothesis. J. Geophys. 40:513-536

Lowrie, W. (1977) Intensity and direction of magnetization in oceanic basalts. J. Geol. Soc. 133:61-82

Lowrie, W., Alvarez, W. (1977) Upper Cretaceous-Paleocene magnetic stratigraphy at Gubbio, Italy. Ill. Upper Cretaceous magnetic stratigraphy. Geol. Soc. Am. Bull. 88:374-377

Lowrie, W., Hayes, D.E. (1975) Magnetic properties of oceanic basalt samples. In: Hayes, D.E., Frakes, L.A. (Eds.) Initial Reports of the Deep Sea Drilling Project, Vol. XXVllI, pp. 869-878. Washington: U.S. Government Printing Office

Lowrie, W., Kent, D.V. (1976) Viscous remanent magnetization in basalt samples. In: Hart, S.R., Yeats, R.S. (Eds.) Initial Reports of the Deep Sea Drilling Project, Vol. XXXIV, pp. 479-484. Washington: U.S. Government Printing Office

Lowrie, W., Lovlie, R., Opdyke, N.D. (1973) Magnetic properties of Deep Sea Drilling Project basalts from the North Pacific Ocean. J. Geophys. Res. 78:7647-7660

Lowrie, W., Opdyke, N.D. (1976) Paleomagnetism of igneous and sedimentary samples. In: Edgar, N.T., Saunders, J.B. (Eds.) Initial Reports of the Deep Sea Drilling Project, Vol. XV, pp. 1017-1022. Washington: U.S. Government Printing Office

Peirce, J.W., Denham, C.R., Luyendyk, B.P. (1974) Paleomagnetic results of basalt samples from DSDP Leg 26, Southern Indian Ocean. In: Davies, T.A., Luyendyk, B.P. (Eds.) Initial Reports of the Deep Sea Drilling Project, Vol. XXVI, pp. 517-527. Washington: U.S. Government Printing Office

Petherbridge, J. (1977) A magnetic coupling occurring in partial self-reversal of magnetism and its association with increased magnetic viscosity in basalts. Geophys. J. Roy. Astron. Soc. 50:395-406

Soffel, H. (1971) The single domain-multidomain transition in natural intermediate titanomagnetites. Z. Geophysik 37:451-470

Stacey, F.D., Banerjee, S.K. (1974) The physical principles of rock magnetism, pp. 190. Elsevier

Steiner, M.B., Helsley, C.E. (1975) Magnetic field polarity during the Late Jurassic (abs.) EOS 56:354

Talwani, M., Windisch, C.C., Langseth, Jr., M.G. (1971) Rekjanes Ridge Crest: a detailed geophysical study. J. Geophys. Res. 76:473-517

Tarasiewicz, G., Tarasiewicz, E., Harrison, C.G.A. (1976) Some magnetic properties of Leg 34 rocks. In: Hart, S.R., Yeats, R.S. (Eds.) Initial Reports of the Deep Sea Drilling Project, Vol. XXXIV, pp. 473-478. Washington: U.S. Government Printing Office

Taylor, P.T., Watkins, N.D., Greenewalt, D. (1973) Magnetic property analysis of basalt beneath the quiet zone. EOS 54:1030-1032

Vine, F.J., Matthews, D.H. (1963) Magnetic anomalies over oceanic ridges. Nature 199:947-949

Vogt, P.R., Anderson, C.N., Bracey, D.R. (1971) Mesozoic magnetic anomalies, sea-floor spreading and geomagnetic reversals in the southwestern North Atlantic. J. Geophys. Res. 76:4796-4823

Weissel, J.K., Hayes, D.E. (1972) Magnetic anomalies in the Southeast Indian Ocean. In: Hayes, D.E. (Ed.) Antarctic Oceanology II: The Australian-New Zealand Sector. Series 19, 165-196. Washington: D.C., AGU Antarctic Research

Wilson, R.L., Watkins, N.D. (1967) Correlation of petrology and natural magnetic polarity in Columbia plateau basalt. Geophys. J. 12:405-424