Skip to main content

Advertisement

Paleomagnetism of Pliocene to Pleistocene lava flows in the northern part of Hyogo prefecture, Southwest Japan and Brunhes Chron paleosecular variation in Japan

Article metrics

  • 241 Accesses

  • 5 Citations

Abstract

Paleomagnetic investigation was performed on 26 Potassium-Argon dated Pliocene to Pleistocene lava flows, collected at 34 sites from northern Hyogo, Southwest Japan. Most magnetic polarities were found to be coincident with the geomagnetic polarity timescale (GPTS), although two lava flows do not agree with the timescale. One of 2 lava flows incompatible with the GPTS, the Oliveine Andesite lava flow from the Oginosen volcano group dated at 0.92 + / − 0.05Ma, shows normal polarity. This finding is a possible evidence confirming the existence of the Santa Rosa Event proposed recently. Twenty-two paleomagnetic data sets were used to investigate paleosecular variation (PSV) having passed the following criteria: 1) characteristic components are obtained from four specimens or more for a lava flow, 2) ケ95 of the lava flow mean direction is < 10° and 3) the virtual geomagnetic pole (VGP) latitude calculated is > 50° or < −50°. The mean VGP was calculated to be latitude = 85.5°N and longitude = 285.3°E (k = 34.8 and ケ95 = 5.3°). The resultant angular standard deviation (ASD) with respect to the geographic pole was calculated to be 14.5° with the upper limit = 18.3° and the lower limit = 12.1°. The ASD value is almost equal to most existing results from the Japan Islands. Brunhes Chron PSV in Japan was estimated using the identical criteria for selection; 66 of 87 available data sets passed. The mean VGP was calculated to be latitude = 89.3°N and longitude = 14.4°E (k = 33.1 and ケ95 = 3.1°). The resultant ASD with respect to the geographic pole was calculated to be 14.2° with the upper limit = 16.1° and the lower limit = 12.7°. The ASD values for the past 3 million years in northern Hyogo and for the Brunhes Chron in Japan are compatible with the global trend for the past 5 million years fitted by physical PSV Model F and phenomenological PSV Model G. This suggests that the PSV in Japan is not low compared with anomalously low PSV area in the Pacific Region.

References

  1. Cande, S. C. and D. V. Kent, Revised calibration of the geomagnetic polarity timescale for the Late Cretaceous and Cenozoic, J. Geophys. Res., 100, 6093–6095, 1995.

  2. Cox, A., Analysis of present geomagnetic field for comparison with paleomagnetic results, J. Geomag. Geoelectr., 8, 101–112, 1962.

  3. Cox, A., Confidence limits for the precision parameter κ, Geophys. J. R. astr. Soc., 18, 545–549, 1969.

  4. Cox, A., Latitude dependence of the angular dispersion of the geomagnetic field, Geophys. J. R. astr. Soc., 20, 253–269, 1970.

  5. Doell, R. R. and A. Cox, The pacific geomagnetic secular variation anomaly and the question of lateral uniformity in the lower mantle, The Nature of the Solid Earth, pp. 245–285, McGraw-Hill, New York, 1972.

  6. Furuyama, K., Geology of the Teragi Group, Southwest Japan—with special reference to the Terada Volcanics—, J. Geosci. Osaka City Univ., 32, 123–173, 1989.

  7. Furuyama, K., K. Nagao, K. Kasatani, and S. Mitsui, K-Ar ages of the Kannabe Volcano Group and the adjacent basaltic monogenetic volcanoes, east San-in district, Earth Science (Chikyuu Kagaku), 47, 377–390, 1993a (in Japanese with English abstract).

  8. Furuyama, K., K. Nagao, S. Mitsui, and K. Kasatani, K-Ar ages of Late Neogene monogenetic volcanoes in the east San-in district, Southwest Japan, Earth Science (Chikyuu Kagaku), 47, 519–532, 1993b.

  9. Genbudo Research Group, High-P and low-Si and -K Quaternary lava from Genbudo, northern Kinki district, Japan, Earth Science (Chikyuu Kagaku), 43, 231–236, 1989.

  10. Genbudo Research Group, Geology and petrology of Quaternary volcanic rocks from the Genbudo area, northern Hyogo Prefecture, southwest Japan—Genbudo and Akaishi lavas—, Earth Science (Chikyuu Kagaku), 45, 131–144, 1991 (in Japanese with English abstract).

  11. Heki, K., Paleomagnetic study of the Higashi-Izu monogenetic volcano group and pyroclastic flow deposits in Kagoshima Prefecture: Paleosecular variation during the last 40,000 years in Japan, J. Geomag. Geoelectr., 35, 383–390, 1983.

  12. Ishikawa, N. and T. Tagami, Paleomagnetism and fission-track geochronology on the Goto and Tsushima Islands in the Tsushima strait area: Implications for the opening mode of the Japan Sea, J. Geomag. Geoelectr., 43, 229–253, 1991.

  13. Kirschvink, J., The least-squares line and plane and the analysis of palaeomagnetic data, Geophys. J. R. astr. Soc., 62, 699–718, 1980.

  14. McElhinny, M. W. and R. T. Merrill, Geomagnetic secular variation over the past 5 my, Rev. Geophys. Space Phys., 13, 687–708, 1975.

  15. McElhinny, M. W., P. L. McFadden, and R. T. Merrill, The myth of the Pacific dipole window, Earth Planet. Sci. Lett., 143, 13–22, 1996.

  16. McFadden, P. L. and M. W. McElhinny, A physical model for palaeosecular variation, Geophys. J. R. astr. Soc., 78, 809–823, 1984.

  17. McFadden, P. L., R. T. Merrill, and M. W. McElhinny, Dipole/quadrupole family modeling of paleosecular variation, J. Geophys. Res., 93, 11,583–11,588, 1988.

  18. McFadden, P. L., R. T. Merrill, M. W. McElhinny, and S. Lee, Reversals of the Earth’s magnetic field and temporal variations of the dynamo families, J. Geophys. Res., 96, 3923–3933, 1991.

  19. Otake, H., H. Tanaka, M. Kono, and K. Saito, Paleomagnetic study of Pleistocene lavas and dikes of the Zao Volcano Group, J. Geomag. Geoelectr., 45, 595–612, 1993.

  20. Roberts, P. H. and M. Stix, a-effect dynamos by the Bullard-Gellman formalism, Astron. Astrophys., 18, 453–466, 1972.

  21. Sakiyama, T., T. Matsuda, H. Morinaga, A. Goto, and S. Kato, Pliocene to Pleistocene volcanic rocks in northern Hyogo Prefecture, Southwest Japan—K-Ar age, paleomagnetism and major elements—, Humans and Nature, 6, 149–170, 1995 (in Japanese with English abstract).

  22. Shibuya, H., J. Cassidy, I. E. M. Smith, and T. Itaya, Paleomagnetism of young New Zealand basalts and longitudinal distribution of paleosecular variation, J. Geomag. Geoelectr., 47, 1011–1022, 1995.

  23. Singer, B. S., K. A. Hoffman, A. Chauvin, R. S. Coe, and M. S. Pringle, Dating transitional magnetized lavas of the late Matuyama Chron: Toward a new 40Ar/39Ar timescale of reversals and events, J. Geophys. Res., 104, 679–693, 1999.

  24. Tsunakawa, H. and Y. Hamano, Paleomagnetic study of the Ashitaka dike swarm in Central Japan, J. Geomag. Geoelectr., 40, 221–226, 1988.

  25. Tsunakawa, H., K. Heki, and K. Amano, Paleomagnetism of the Shimokura dike swarm in Northeast Japan, J. Geomag. Geoelectr., 37, 979–985, 1985.

Download references

Author information

Correspondence to H. Morinaga.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Morinaga, H., Matsumoto, T., Okimura, Y. et al. Paleomagnetism of Pliocene to Pleistocene lava flows in the northern part of Hyogo prefecture, Southwest Japan and Brunhes Chron paleosecular variation in Japan. Earth Planet Sp 52, 437–443 (2000) doi:10.1186/BF03352255

Download citation

Keywords

  • Andesite Lava
  • Paleomagnetic Result
  • Virtual Geomagnetic Pole
  • Paleomagnetic Polarity
  • Hyogo Prefecture