The PML Group

2 Evaluation of Research Activities at ISEI

{E. Nakamura, A. Makishima, T. Moriguti}

During the last five years the most impressive new development at ISEI was the establishment of a very extensive solid-state geochemistry lab by E. Nakamura (the PML: Pheasant Memorial Laboratory). A great amount of resources have been concentrated to establish the PML. The PML now can analyze about half of the elements in the periodic table by ICPMS or TIMS up to the highest precision and to the lowest detection limit. Multi-isotope analysis can be also done by array of TIMS using as much as seven isotope systems. It has two most modern SIMS and they are also linked on line with image analysis by a SEM and major element analysis with EPMA. All this is very exceptional, even for the best equipped laboratories in the world.
Besides its brand new equipment, the strength of the PML is the strong leadership of E. Nakamura and tight collaboration with research staffs Makishima and Moriguti. The PML also has relatively large number of post-docs and graduate students who are also very well trained. In the last five years, E. Nakamura produced six PhDs from his group. In Europe and United States, the array of modern equipment in the PML would require large number of technicians and supporting staffs. Here the scientists and their graduate students are taking the role. Nevertheless, the instruments at PML are operated in the best conditions and many new techniques in chemistry and mass spectrometry are being investigated.
PML clearly now is one of the most well equipped and technically advanced solid-state geochemistry labs in the world. Impressive also is the very rational way by which the whole system (clean rooms, mass-spectrometry rooms, ionic probe apparatus etc.), has been assembled together. This has been possible by avoiding the rush in piling up equipment over one another. There has also been a lot of reflection in elaborating original analytical procedures adapted to the new array of machines. This presently results in a rather high proportion of analytical papers (in good journals though) versus fundamental geochemistry ones. That proportion should normally be reversed in the near future and establish world reputation in isotope geochemistry.

2.2 The High-Pressure Group

{E. Ito, T. Katsura,A. Yoneda, M. Walter, M. Kanzaki}

Historically, ISEI has been strong and internationally well-recognized for its very high-pressure experiments on phase relations in mantle rocks and related materials. Phase diagrams created by E. Ito served as benchmarks in many fields of earth science. The Misasa style multi-anvil press has been exported to several overseas institutes and has now become standard equipment in high-pressure earth sciences around the world. The tradition is still very strong and active.
In addition to the phase relation studies, the high-pressure group in ISEI has broken new ground in the precise measurement of the physical properties of minerals. Thermal conductivity and electrical conductivity measurements of deep mantle minerals by T. Katsura are excellent examples of this new world-leading effort. A. Yoneda is building an ultrasonic laboratory in which elastic and anelastic properties of mineral specimens will be measured using state-of-the-art resonance techniques.
The present frontier of the pressure generation with multi-anvil devices is being explored by E. Ito using sintered diamond anvils. The highest pressure (recorded by the equation of state of Au and MgO using the SPring-8 synchrotron facility) is 40 GPa. In order to make these sintered diamond anvil experiments truly successful, however, adequate investment may be necessary (e.g.; fabrication equipment for the sintered diamond cubes and an annual supply of suitable raw materials).
A state-of-the-art diamond-anvil cell (DAC) laboratory is being set up by Walter. The DAC is a welcome, complementary technique to the historically strong large volume multi-anvil program and should be strongly supported. The NMR facility recently installed by Kanzaki is an important addition to the high-pressure experiment group (though both Walter and Kanzaki are formally in the Basic Volcanology group). It is noteworthy that these major facilities were acquired not under the Institution's budget but by competitive research grants.
Considering coverage of the ISEI scientists, one obvious missing component would be a mineralogist and crystallographer for structural characterization using X-ray diffraction and analytical TEM (transmission electron microscope). It is critically important for the very-high pressure group (both the large volume and the DAC apparatus) in its study of new phases and materials. In DAC experiments, analytical TEM is an ideal way to obtain chemical and crystallographic information.
The third generation synchrotron SPring-8 was established in 1997 in Nishiharima. The high pressure group at ISEI was expected to play a leading role at the SPring-8 facility because of its high technical level and the number of staffs. Several important researches were being done by the high-pressure group of ISEI at SPring-8 (e.g., the stability field of MgSiO₃ perovskite, viscosity of silicate melt). Its real power may be revealed if adequate number of graduate students are involved in these experiments.

2.3 Basic Volcanology

{K. Ozawa, M. Kusakabe, S. Yamashita,M. Kanzaki, M. Walter}

A new research branch (Basic Volcanology) was established at the time of reorganization in 1995. This branch was aimed to link the two strong branches in ISEI (very high-pressure experiments and the PML) by introducing insights of magmatology (volcanology, igneous petrology, and silicate melt science). After retirement of Kushiro, the former director, who represented the character of this branch, and the recent move of Ozawa to Tokyo (in April 2000), this branch clearly needs personnel who can play key roles to interact between the two strong groups.
M. Kusakabe (stable isotope geochemist) and S. Yamashita (experimental petrologist) are in the Basic Volcanology branch. Kusakabe has extensively studied the instability of volcanic crater lakes after the accident in the lake Nyos in Cameroon. Yamashita studies water solubility in silicate melts to discuss dynamics of volcanic eruptions. The stable isotope equipment is apparently in good condition and works satisfactorily. However, except for the PRISM, the more recent but also apparently the most troublesome, the other mass spectrometers all belong to the same technical period of stable isotope geochemistry, that is about ten to fifteen years ago. There is a plan to introduce the more sensitive and more discriminating equipment such as continuous flow, CPG-IRMS coupling and static machines, which could extend the capabilities of the whole institute, in particular for the isotope analysis of the tiny products of high-pressure experiments.
M. Walter is currently in the Basic Volcanology group. This is reasonable in that his research targets (e.g., origin of Archean komatiite magmas, crystallization in the Hadean magma ocean) are magma-related problems. He may be grouped as a member in the high-pressure group because he has interest and experienced with multi-anvils as well as running the new DAC lab. Although other scientists in the high-pressure group are oriented to mineral-physics M. Walter's interests are extended towards geochemistry. In this regard, his role as a key person to bridge the solid-state mass spectrometry group and the high-pressure group is a great asset to ISEI as well as his role to link ISEI with international earth science communities. Likewise, M. Kanzaki is currently in the Basic Volcanology group. However, with his strong background and expertise in high-pressure experiments and crystal chemistry, Kanzaki's role as a mineralogist in the high-pressure group is likewise an important link.
Of course a much simpler organization could prevail to reflect the various skills and interests in the staff, that is geochemistry (including petrology and stable and radiogenic isotopes) and high pressure mineral physics, corresponding also to the equipment, and more similar to the organization of comparable institutes in the world.

2.4 Others

{M. Kono, H. Chiba, N. Kishima}

Another stable isotope geochemist (H. Chiba) and a geochemist on hydrothermal fluids (N. Kishima) are in the Planetary Material Science division as well as PML. Very little interaction was seen between PML and these two. Since these geochemists originated and inherited H. Sakai's (moved to Tokyo University in 1984 and retired) stable isotope lab and the rock-water interaction lab, respectively, and their works are all related to magmatic hydrothermal process as well as Kusakabe and Yamashita, we wondered why Chiba and Kishima is not in the Basic Volcanology branch but in the Planetary Material Science branch. Because Chiba came back to ISEI from Kyushu University only short while ago, his work on hydrothermal environment at oceanic ridges was not yet fully advanced in Misasa. We expect further developments of his work in a near future.
Kono moved from Geophysics and Planetary-Physics department, University of Tokyo in March of 1999. The Committee member finally visited his office to listen his most recent achievement in self-consistent earth-dynamo theory. With a student who followed after him from Tokyo, Kono is working on paleomagnetism of some volcanic rocks in the world (e.g., Iceland). We are very impressed that he is still very active as a scientist as well as an administrator.

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