Structural and Sedimentary Field Studies in Angul District, Odisha, India

The Angul District of Odisha exposes excellent and accessible outcrops of Archean-Proterozoic metamorphics and migmatites, near-horizontal Gondwana Supergroup of sedimentary succession and the overlying Quaternary deposits with an unconformable relationship between the Archean-Proterozoic and the Gondwanas, but that is not exposed. The Archean-Proterozoic rocks are the oldest and form the basement in the region. Stomatic structures formed by alternating quartzo-feldspathic leucosome bands and the dark mafic melanosome layers are conspicuous. The granularity is high with garnets reaching nearly 1.2 cm diameter. Folding, fracturing, faulting and mafic intrusives are also observed at many places. The country rock in most part is Khondalite associated with charnockites and migmatites. Superposed folds indicate several generations of folding. The khaki shales and greyish white sandstones of Talchir Formation and the greyish sandstones of Barakar Formation constitute most of the sedimentary exposures of the Gondwana along with exposures coal seams and carbonaceous shales. Various sedimentary structures are observed in the Barakar sandstones and lithological analysis indicates their fluviatile origin with varied energy fluctuations. The Quaternary deposits are fluviatile in origin and contain boulder beds and sand-mud lithology. Paleocurrent analysis from the boulders and cross stratifications indicates flow direction sub-parallel to the present day channel.