Small-Scale Structures in Tuffs Associated with Iron-Ore Volcanics of Barsua Valley, Sundargarh District, Orissa, India

The paper records small-scale primary and secondary structures in different tuffaceous rocks of Barsua Valley, Sundargarh district, Orissa, India. The tuffs of acid, basic and intermediate composition are structurally both isotropic and anisotropic and form a part of the sheet-like tuff-tufflava-lava sequence of the Precambrian Iron-Ore Volcanics.

The primary bedding structures like tuff layers and laminations. cross-lamination and graded-bedding; secondary (deformational) structures like small-scale polyphase folds, their interference structures and associated boudins; distinctive structures, viz., small-scale faults etc. are described. Pre-tectonic soft sediment deformational structures are obscured by the imprint of tectonic structures.