Name : KANEOKA,  Ichiro
            Position : Professor
            Division/Center : Division of Geodynamics
            Research Area : Isotope Earth and Planetary Sciences, Geochronology
 
 
 

RESEARCH

In our group, we have been studying the fundamental processes related to the volcanism(especially global ones such as hotspot and
       ridge volcanisms) and the evolution of the Earth based on radiometric dating methods(K-Ar and Ar-Ar), isotope studies (e.g.,noble
       gas isotopes and10Be), chemical and mineralogical compositions of rocks and related minerals. To clarify the evolution of the Earth,
       we have also investigated extraterrestrial materials such as meteorites. In these several years, we have focussed our attention on
       samples from Pacific and Indian Ocean areas as the case for global volcanisms and also apply the noble gas isotopes to reveal the
       effect of underground water to magma systematics and to identify the occurrence of recycled materials on global scale in the Earth's
       deep interior. Through such studies, we have obtained the following results.
       (1) We have revealed the evidence for the contribution of recycled materials to HIMU and EM type magmas for OIB(oceanic island
       basalts). Two types of xenolithic rocks have been identified in OIB, one of which was affected by recycled materials and the other not
       affected.
       (2) We have proposed a model on the chemical structure of the Earth which is compatible with the information described in (1)
       together with other information on isotopic constraints and observations by seismic tomography.
       (3) It has been suggested the existence of thermal water circulation with a relatively large extent underneath the ridge and its effect
       on the magma based on noble gas signatures.
       (4) We have found an old activity of the Deccan volcanism exceeding 70Ma in the limited area as the Mandla Trap located at the
       northeastern part of the Deccan Traps.
       (5) We have pointed out the possible incorporation of the underground water into the magma at the Unzen Volcano eruption based on
       the 40Ar/36Ar.
       (6) Based on 10Be/9Be in volcanic rocks, we have verified the incorporation of sediments into the arc magma under the Japanese
       Islands. We further investigate the relationships between the primordial and the recycled components of volatile elements in the
       Earth's deep interior and its significance to the evolution of the Earth.
 

RESEARCH

Hanyu, T., I. Kaneoka and K. Nagao, Noble gas study of HIMU and EM ocean island basalts in the Polynesian region, Geochim. Cosmochim. Acta, 63, 7/8, 1181--1201, 1999.

Iwata, N. and I. Kaneoka, On the relationships between the 40Ar-39Ar dating results and the conditions of basaltic samples, Geochem. J., 34, 4, 271--281, 2000.

Naka, J., E. Takahashi, D. Claue, M. Garcia, T. Hanyu, E. Herrero-Bervera, J. Ishibashi, O. Ishizuka, K. Johnson, T. Kanamatsu, I. Kaneoka, P. Lipman, A Malahoff, G. McMurtry, B. Midson, J. Moore, J. Morgan, T. Naganuma, K. Nakajima, T. Oomori, et al, Tectono-magmatic processes investigated at deep-water flanks of Hawaiian volcanoes, EOS (Trans. Am. Geophys. Union), 81, 20, 221--227, 2000.

Kaneoka, I., Earth's history trapped in the mantle, Science, 288, 5468, 988--989, 2000.

Kaneoka, I., Recent activities of geochronological studies in Japan(1996-1997), Phanerozoic Time Scale, Bull. Liais. Inform. IUGS Subcom. Geochronol., 15, 42--48, 1999.