1998 Fiscal Year Final Research Report Summary
THE STRUCTURES AND PHYSICAL PROPERTIES OF MAGMAS
| Project/Area Number |
09044069
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| Research Category |
Grant-in-Aid for international Scientific Research
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| Allocation Type | Single-year Grants |
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| Section | Joint Research |
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| Research Field |
Petrology/Mineralogy/Science of ore deposit
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| Research Institution | KANAZAWA UNIVERSITY |
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Principal Investigator |
OKUNO Masayuki Kanazawa Unversity, Faculty of Science, Associate professor, 理学部, 助教授 (40183032)
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| Co-Investigator(Kenkyū-buntansha) |
WILLAIME Christian Unversite de Rennes I,Institut de Geologie, Professor, Institut de Geol, 教授
REYNARD Bruno Ecole Normale Superiure Lyon, Laboratoire Science de la Terre, CNRS 1st class Re, Laboratoir, CNRS一級研究員
KIHARA Kuniaki Kanazawa Unversity, Faculty of Science, Professor, 理学部, 教授 (70019503)
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| Project Period (FY) |
1997 – 1998
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| Keywords | magma / glass / structure analysis / X-ray diffraction method / Raman spectroscopy / volcanic glass / plagioclase |
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| Research Abstract |
Principle results on the structures of feldspar and volcanic glasses for analyzing structures and physical properties of magmas under high temperature and pressure conditions were followed.
a) The shock-wave densification of SiO2 glass was analyzed by X-ray diffraction and Raman spectroscopy. SiO2 glass was densified up to 25GPa and the density decreased upper pressure by high residual temperature.
b) Feldspar (NaAlSi_3O_8 CaAl_2Si_2O8) glasses were compressed under 500^OC/4GPa and 7.7GPa by cubic press apparatus. The structures of these glasses were analyzed by Raman spectroscopy. From these observations, it was evident that the structure of plagioclase glass has smaller ring structure of TO_4 tetrahedra and the coordination numbers of Al atoms change from 4 to 6 under high temperature and high pressure conditions. Shock experiment for CaAl_2Si_2O_8 glass was also performed to reveal the density increase was smaller than that of SiO2 glass and this density increase was based on the increase of three membered rings of TO_4 tetrahedra. The annealing process of shock-wave denshified CaAl_2Si_2O_8 glass was also investigated by in-situ Raman spectroscopy. These results are very important to understand Al bearing magma.
c) The structures of densified volcanic glasses obtained by shock and static compressions were investigated by Xray diffraction and Raman spectroscopy techniques. The densification of volcanic glass (about 9%) by 500^OC/7.7GPa static compression may be due to change from 6 and 5 membered ring of TO_4 tetrahedra dominant structure to 4 and 3 meinbered ring dominant structure. On the other hand, crystallites in the obsidian vitrified by shock-wave compression and the density did not increase but decrease at higher shock pressure(25 and 35GPa).
d) These results were discussed in Japan and France by all project members and we prepared some scientific papers.
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