1991 Fiscal Year Final Research Report Summary
Geological and isotopical studies on the Precambrian basement of the Baltic Shield.
| Project/Area Number |
02041036
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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 | Field Research |
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| Research Institution | Shinshu University, Department of Geology. |
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Principal Investigator |
KURODA Yoshimasu Professor of the Department of Geology, Shinshu University, 理学部, 教授 (20015530)
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| Co-Investigator(Kenkyū-buntansha) |
OHTA Yoshihide Chief Geologist of the Polarinstitute of Norway., 主任研究官
MATSUO Sadao Professor of the Department of Chemistry, University of Electro-Communication., 教授 (30015490)
MARUYAMA Takahiko Professor of the Department of Mining Geology, Akita University., 鉱山学部, 教授 (60006682)
ISHIKAWA Kenichi Assistant of the Department of Geology, Tohoku University., 教養部, 助手 (20158744)
KANISAWA Satoshi Professor of the Department of Geology, Tohoku University., 教養部, 教授 (70005784)
YAMAGUCHI Yoshiaki Associate Professor of the Department of Geology, Shinshu University., 理学部, 助教授 (50144689)
YAMADA Tetsuo Professor of the Department of Geology, Shinshu University., 理学部, 教授 (30020647)
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| Project Period (FY) |
1990 – 1991
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| Keywords | Granite / Baltic Shield / Hydrogen isotope / Hornblende / Biotite / Mobil belt / Fe / Fe+Mg / Water content |
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| Research Abstract |
We have determined the deltaD-X_<Fe> relationship of coexisting hornblende and biotite from the various rapakivi granites in the Baltic shield. The age of the rapakivi granite is in the range of 1.70-1.55Ga. The deltaD-X_<Fe> pattern of the rapakivi is quite different from those of the Japanese granitic rocks. Namely the deltaD value of hornblende is very low (--120%_0) and that of biotite is rather high (--80%_0), though the X_<Fe> value of both minerals is nearly equal with a high value (O. 8-0.9). The water (OH) content of hydrous minerals, especial amphiboles, from rapakivi granites is significantly low compared with those of the Japanese granitic rocks. The deltaD-X_<Fe> relationship of the most Japanese Cretaceous granites is completely concordant with that based on the experimental investigation by Suzuoki and Epstein.
The anorogenic rapakivi granites intruded into the cratonic crust, and the original magma would have been generated in the upper mantle or the lowest crust, where the molecular water content must have been quite low.
The Sveconorwegian granites, younger than rapakivi (l. 0-0.8Ga), intruded into probably cratonic condition as rapapkivi, but the deltaD-X_<Fe> diagram is different from that of rapakivi and also from Japanese granitic rocks. X_<Fe> value of hornblende and biotite is almost the same. withi-low. (0.4-0.6) value, deltaD value of hornblende and biotite is opposite compared with that of rapakivi, OH contente of both minerals are very low (lower than that of rapakivi), and F content is very high especially in biotite. In the Caledonian belt of NW Norway, the Paleozoic granites appeared and their deltaD-X_<Fe> relatioship is quite similar to that of the Japanese granitic rocks (mobil belt-island arc).
The geochemical characteristics of granitic rocks in the Baltic shield are clarified.
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[Publications] Kuroda,Y.,Yamada,T.,Yoshinari,A.and Matsuo,S.: "Origin of fumarolic and magmatic water in an acid volcano, Yakedake,central Japan." Marumo,F.ed.,Dynamic Processes of Material Transport and Transformation in the Earth's Interior.409-419 (1990)
Description
「研究成果報告書概要(和文)」より
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[Publications] Kanisawa, S., Yoshida, T., Ishikawa, K., Kuroda, Y., Yamada, T., Morikiyo, T. Maruyama, T. and Aoki, K.: "Preliminary study of the trace elements geochemistry of some Proterozoic granites, Sweden." Res. Report of Lab. Nuclear Sci., Tohoku Univ.24. 312-329 (1991)
Description
「研究成果報告書概要(欧文)」より
