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Magnetic structure of the southern Boso Peninsula, Honshu, Japan, and its implications for the formation of the Mineoka Ophiolite Belt


We conducted onshore and offshore magnetic surveys on and around the southern Boso Peninsula, Honshu, Japan, and observed prominent large amplitude anomalies along the Mineoka Ophiolite Belt, and long wavelength low anomalies to the south of the belt containing short wavelength isolated anomalies. The magnetic structure was modeled by using three-dimensional magnetic prisms and basement with about 1 A/m of magnetization. At the Mineoka Belt, the top of the magnetic prisms is located at the ground surface, and these bodies are elongate in the vertical direction, with high angle magnetic inclinations. Magnetic basement exists at shallow depth beneath the belt. The magnetic basement traces the bottom surfaces of the magnetic prisms and forms a graben structure. In the south of the Mineoka Belt, thin sheet-like magnetic prisms with low magnetic inclinations are assumed at 1–3 km depth. The magnetic structure implies the tectonic process of the formation of the Mineoka Ophiolite Belt. The belt could be fragmented pieces of an oceanic plate emplaced at a paleo-plate boundary, which originated in low latitude and was transported by obduction to the present place via northward drift.


  1. Arai, S., M. Ito, N. Nakayama, and F. Masuda, A suspect serpentine mass in the Tokyo Bay area: petrology and provenance of serpentinite pebbles in the upper Cenozoic system in the Boso Peninsula, central Japan, J. Geol. Soc. Japan, 96, 171–179, 1990 (in Japanese with English abstract).

  2. Arai, S., The Circum-Izu Massif Peridotite, Central Japan, as Back-Arc Mantle Fragments of the Izu-Bonin Arc System, Ophiolite Genesis and Evolution of the Oceanic Lithosphere, Proceedings of the Ophiolite Conference, Held in Muscat, Oman, 7–18January 1990, pp. 801–816, Kluwer Academic Publishers, Dordrecht, the Netherlands, 1991.

  3. Arai, S. and H. Okada, Petrology of serpentine sandstone as a key to tectonic development of serpentine belts, Tectonophys., 195, 65–81, 1991.

  4. Asano, S., Y. Ichinose, I. Hasegawa, S. Iizuka, and H. Suzuki, Crustal structure in the southern Kanto district derived from explosion seismic data, J. Seismol. Soc. Japan, 2, 32, 41–55, 1979 (in Japanese with English abstract).

  5. Bhattacharyya, B. K., Magnetic anomalies due to prism-shaped bodies with arbitrary polarization, Geophys., 29, 517–531, 1964.

  6. Chenot, D. and N. Debeglia, Gravity and magnetic 3-D interactive inversion with constraints, 56th Ann. Internat. SEG Mtg., Expanded abstracts with Biographics, 219–221, 1986.

  7. Fujiwara, T., Study of crustal structure in the southern part of Boso Peninsula inferred from magnetic anomalies and its tectonic implications, M.S. Thesis, Chiba Univ., 1990.

  8. Fujiwara, T, S. Ogura, R. Morijiri, and H. Kinoshita, The crustal structure of the southern part of Boso Peninsula based on magnetic anomaly study, Rock Mag. Paleogeophys., 17, 100–105, 1990.

  9. Fujiwara, T, N. Seama, M. Yamamoto, N. Isezaki, and H. Kinoshita, Geomagnetic survey of the off-Kamogawa, Boso Peninsula, Japan, JAMSTEC J. Deep Sea Res., 14, 467–476, 1998 (in Japanese with English abstract).

  10. Geological Survey of Japan (GSJ), Off the Coast of Boso-Izu-Sagami Nada Area, Total Intensity Aeromagnetic Maps 1:200,000 Series No. 27, 1980.

  11. Geological Survey of Japan (GSJ), Geological Atlas of Japan, 119 pp., 1982.

  12. Geological Survey of Japan (GSJ) and Coordinating Committee for Coastal and Offshore Geoscience Programs in East and Southeast Asia (CCOP), Magnetic Anomaly Map of East Asia 1:4,000,000 CD-ROM Version, 1996.

  13. Hasegawa, I., Structure of the pre-Tertiary basement beneath the Kanto Plain revealed by geophysical data, Mem. Geol. Soc. Japan, 31, 41–56, 1988 (in Japanese with English abstract).

  14. IAGA Division IWG 1, International Geomagnetic Reference Field revision 1985, J. Geomag. Geoelectr, 37, 1157–1163, 1985.

  15. IAGA Division V WG 8, International Geomagnetic Reference Field, 1995 revision, J. Geomag. Geoelectr, 47, 1257–1261, 1995.

  16. Isezaki, N., A new shipboard three component magnetometer, Geophys., 51, 1992–1998, 1986.

  17. Isezaki, N., H. Inokuchi, H. Ishikawa, H. Ichikawa, K. Takahashi, Y Inoue, and K. Sugimoto, Report on DELP 1987 cruises in the Ogasawara area Part V. Measurement of three components and total intensity of the geomagnetic field in the Ogasawara trough, Bull. Earthq. Res. Inst., Univ. Tokyo, 64, 179–222, 1989.

  18. Japan International Cooperation Agency (JICA), 1:200,000 Total Intensity Aeromagnetic Map over the Uraga Strait, 1983.

  19. Kanehira, K., Mode of occurrence of serpentinite and basalt in the Mineoka district, southern Boso Peninsula, Mem. Geol. Soc. Japan, 13, 43–50, 1976 (in Japanese with English abstract).

  20. Kanehira, K., Y. Oki, S. Sanada, M. Yabe, and F. Ishikawa, Tectonic blocks of metamorphic rocks at Kamogawa, southern Boso Peninsula, J. Geol. Soc. Japan, 74, 529–534, 1968.

  21. Kaneoka, I., Y. Takigami, S. Tonouchi, T. Furuta, Y. Nakamura, and M. Hirano, Pre-Neogene volcanism in the central Japan based on K-Ar and Ar-Ar analyses, in Abstracts 1981 IAVCEI Symposium-Arc Volcanism, Tokyo and Hakone, Volcanol. Soc. Japan, 166, 1981.

  22. Kato, M., Theory of Two-dimensional Filter and Analysis of Gravity and Magnetics, Lattice, 262 pp., Lattice, Tokyo, 1987 (in Japanese).

  23. Kinoshita, H., Y. Nakasa, R. Morijiri, and T. Fujiwara, Formation of backarc basin and genesis of ophiolite, J. Geography, 104, 392–407, 1995.

  24. Komazawa, M. and K. Kishimoto, Bathymetric data around Japan (1 km mesh), News Lett. Seis. Soc. Japan, 7, 4, 3–4, 1995 (in Japanese).

  25. Kono, Y. and N. Furuse, 1:1 Million Scale Gravity Anomaly Map in and around the Japanese Islands, Univ. Tokyo Press, Tokyo, 1989.

  26. Mizoue, M., I. Nakamura, H. Chiba, M. Yoshida, H. Hagiwara, and T. Yokota, Thestructureofthe upper part of the crustinthe regionsofSagami Bay, the Izu Peninsula and Suruga Bay as found by the observation of the earthquake swarm east off the Izu Peninsula in 1980, Bull. Earthq. Res. Inst., 56, 139–160, 1981 (in Japanese with English abstract).

  27. Morijiri, R., Geomagnetic total force anomaly and crustal structure of the Mineoka Belt in the southern part of Boso Peninsula, M.S. Thesis, Chiba Univ., 1988 (in Japanese).

  28. Morijiri, R., T. Fujiwara, S. Ogura, H. Kinoshita, and T. Nagao, Crustal structure and magnetic anomaly in southern part of Boso Peninsula, Chiba, Japan (abstract), EOS Trans. AGU, 71, 942, 1990.

  29. Nakai, J., M. Komazawa, and Y. Okubo, Distribution of gravity anomalies and aeromagnetic anomalies in the Kanto District, J. Geography, 96, 185–200, 1987 (in Japanese with English abstract).

  30. New Energy and Industrial Technology Development Organization (NEDO), Report of geothermal energy research, curie point depth survey of Japan (Kanto and Tokai district), 1983.

  31. Ogawa, Y. and K. Fujioka, Evolution of the plate boundary in the northeastern part of the Izu-arc—From the Mineoka Belt to the Sagami Trough —, Chikyu, 7, 709–719, 1985 (in Japanese).

  32. Ogawa, Y. and H. Taniguchi, Ophiolitic melange in the forearc areas and the development of the Mineoka belt, Sci. Rep. Dept. Geol., Kyushu Univ., 15, 1–23, 1987 (in Japanese with English abstract).

  33. Ogawa, Y. and H. Taniguchi, Geology and tectonics of the MIURA-BOSO peninsulas and the adjacent area, Modern Geology, 12, 147–168, 1988.

  34. Ogura, S., Analysis of geomagnetic anomaly in the southern part of Boso Peninsula by using prism model simulation, B.S. Thesis, Chiba Univ., 1990 (in Japanese).

  35. Okuma, S., M. Makino, and T. Nakatsuka, Two-layer model inversion of magnetic anomalies using pseudogravity and reduction to the pole: An application to the analysis of aeromagnetic anomalies over Izu-Oshima, Butsuri-Tansa, 42, 82–96, 1989 (in Japanese with English abstract).

  36. Research Group for Active Faults of Japan, Active Faults in Japan: Sheet Maps and Investigations (revised edition), 1991.

  37. Saito, S., Stratigraphy of Cenozoic strata in the southern terminous area of Boso Peninsula, Central Japan, Contr. Inst. Geol. Pal, Tohoku Univ., 93, 1–37, 1992.

  38. Smith, W. H. F. and P. Wessel, Gridding with continuous curvature splines in tension, Geophys., 55, 293–305, 1990.

  39. Soh, W., K. T. Pickering, A. Taira, and H. Tokuyama, Basin evolution in the arc-arc Izu collision zone, Mio-Pliocene Miura group, central Japan, J. Geol. Soc. London, 148, 317–330, 1991.

  40. Sugimura, A. and Y. Naruse, Changes in sea level, seismic upheavals and coastal terraces in the southern Kanto region, Japan (I), Japan J. Geol. Geogr., 24, 101–113, 1954.

  41. Sugimura, A. and Y. Naruse, Changes in sea level, seismic upheavals and coastal terraces in the southern Kanto region, Japan (II), Japan J. Geol. Geogr., 26, 165–176, 1955.

  42. Taira, A., H. Tokuyama, and W. Soh, Accretion tectonics and evolution of Japan, in The Evolution of Pacific Ocean Margins, edited by Zniben-Averaham, pp. 100–123, Oxford Univ. Press, New York, Oxford, 1989.

  43. Takigami, Y, I. Kaneoka, and M. Hirano, K-Ar and Ar-Ar dating on ophiolites from Mineoka, Bull. Volcanol. Soc. Japan, 25, 308, 1980.

  44. Tonouchi, S. and K. Kobayashi, Paleomagnetic and geotectonic investigation of ophiolite suits and surrounding rocks in south central Honshu, Japan, in Accretion Tectonics in the Circum-Pacific Regions, edited by M. Hashimoto and S. Uyeda, pp. 261–288, Terra Sci. Publ. Tokyo, 1983.

  45. Uchida, T. and S. Arai, Petrology of ultramafic rocks from the Boso Peninsula and the Miura Peninsula, J. Geol. Soc. Japan, 84, 561–570, 1978.

  46. Ueda, Y, H. Nakagawa, T. Hiraiwa, T. Asao, and R. Kubota, Gravity anomalies and derived subterranean structure on/around Tokyo bay and southern Kanto district, Rep. Hydrographic Res., 22, 179–206, 1987.

  47. Wessel, P. and W. H. F. Smith, Free software helps map and display data, EOS Trans. AGU, 72, 441, 445–446, 1991.

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Correspondence to Toshiya Fujiwara.

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Fujiwara, T., Kinoshita, H. & Morijiri, R. Magnetic structure of the southern Boso Peninsula, Honshu, Japan, and its implications for the formation of the Mineoka Ophiolite Belt. Earth Planet Sp 51, 413–424 (1999).

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  • Magnetic Anomaly
  • Natural Remanent Magnetization
  • International Geomagnetic Reference Field
  • Ophiolitic Rock
  • Japan International Cooperation Agency