Author Details

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.

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