1991 Fiscal Year Final Research Report Summary
Multiple deformations of the Sangun metamorphic rocks
| Project/Area Number |
02640599
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
地質学一般
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| Research Institution | Hiroshima University |
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Principal Investigator |
OHO Yukimasa Fac. Integrated Art. and Sci., Hiroshima Univ., Associate Prof., 総合科学部, 助教授 (80152560)
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| Project Period (FY) |
1990 – 1991
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| Keywords | Sangun metamorphic / Deformational micostructure / Geologic structure / Multiple deformations |
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| Research Abstract |
Study of microstructures, and also mapping and structural analysis of the Sangun metamorphic rocks in the OchiaiAsahi, Suma(Tokuyama city)and Kurume-Joyou areas all indicate that the Sangun metamorphic rocks have undergone four times of deformations. The first produced isoclinal flow folds(F_1)with axial plane schistosity(S_1). This was related to the Sangun metamorphism. The second deformation folded the S_1 schistosity to form crenulation cleavage folds(F_2). The F_2 folds generally have chevron or kink shapes with wavelengths from a few millimeters to several centimeters. The axial surfaces of F_2 range from WNW-ESE to ENE-WSW in strike, and from 10^0 to 90^0 in the dip angle. The second deformatiojn occurred after the deposition of Jurassic Chizu Formation. The crenulation cleavage(S_2)was folded again by the third deformation. F_3 folds were open in shape and had crenulation cleavage(S_3). Wavelengths of the F_3 folds range from 1 mm to 10 cm. The attitudes of fold axes vary with places ; the axes trend N-S or NNW-SSE in the Ochiai-Asahi area, WNW-ESE or NW-SE in the Suma and Kurume-Joyou areas. After the third deformation, the major well-known E-W trending folds(F_4)were formed during the Early Cretaceous. Wavelength of the F_4 folds is several kilometers on a mappable scale. The second, third and fourth deformations probably occurred during the uplifting of the Sangun metamorphic rocks.
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Research Products
(8 results)
