1992 Fiscal Year Final Research Report Summary
Comparative study on structural geology of tectonic melange,olistostrome and mud volcano.
| Project/Area Number |
03804064
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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 | KYUSHU UNIVERSITY |
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Principal Investigator |
SAKAI Harutaka Kyushu University,College of General Education Earth Science Associate Professor, 教養部, 助教授 (90183045)
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| Project Period (FY) |
1991 – 1992
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| Keywords | Melange / Olistostrome / Submarine Slide / Subaqueous Pyroclastic Flow / Mud Volcano / Lesser Himalayas / Nappe / Augen Gneiss |
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| Research Abstract |
As a result of present study,I obtained the following new knowledge and idea about olistostrome and melange. 1.Olistostrome(huge submarine slide) A huge submarine slide intercalated in the Taishu Group in Tsushima has a characteristic change of geologic structures from the base to the top.(1)injection of sand dyke and sheet below the base,(2)low-angle normal faults above the base,(3)gentle and closed folds,(4)recumbent folds and low-angle thrusts, (5)box-shaped and rootless folds,(6)chaotic slump-ball zone. This change of structures can be a criteria to distinguish olistostrome from tectonic melange. 2. Tectonic Melange Augen gneiss exposed along the Main Central Thrust(MCT) zone in the Himalayas is a kind of tectonic melange which has under-gone deformation along plate boundary in the middle to deep part of crust. It cane be originated by slow cooling and shearing of inner part of sheet-formed leucogranite.
Tectonic melange on the sole of para-autochthonous klippe and nappe in the Lesser Himalayas has a characteristic rotation texture of cataclastic grains. Garnets in the gneiss along the MCT have also rotation texture,so called snow-ball texture. It is highly possible that rotation texture is a characteristic feature in the shear zone along low-angle thrust and become a criteria to distinguih tectonic melange from olistostrome.
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