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Authors
Affiliations
1 Indian Institute of Technology, Dept. of Earth Sciences, Powai, Mumbai-400 076, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 51, No 2 (1998), Pagination: 219-225
Abstract
The calc-gneiss and garnet-sillimanite-gneiss of Eastern Ghat Mobile Belt around Lathore bear the imprint of multiple phases of deformtion. The folds of the first generation, F1, are isoclinal, intrafolial and vary in style from reclined to upright. This has developed a pervasive axial planar gneissosity. The second generation folds, F2 , which are coaxial with the F1 are open to tight with a planar axial surface dipping moderately to SE and varied plunging axis. At places mesoscopic plane non-cylindrical F2 sheath folds are noticed. Gentle upright folds, F3 , with NW-SE striking axial plane represent structure of third generation. Superimposition of F2 on F1 has resulted in Type 3 interference pattern and dome and basin structures are due to the interference of F2 and F3 folds. F1 and F2 folds are attributed to WNW-ESE buckling and F3 is reported to be due to shortening across it. The 'sheath folds' are due to heterogeneous simple shear aiong the axial plane of the F2 fold. The map shows a large scale southwesterly plunging overturned F2 fold. Post-exhumation deformation has resulted in brittle shearing parallel to the axial plane of F2 fold. The structure of the area points to a collisional tectonic setting like other granulite belts of Gondwanaland.
Keywords
Structural Geology, Eastern Ghat Mobile Belt, Orissa.