Penecontemporaneous Deformational Structures in the Glauconitic Sandstone, Semri Group (Vindhyan Supergroup), Sonbhadra District, Uttar Pradesh, India and their Structural Analysis

Abstract

The Glauconitic sandstone is well exposed in the Newari area of Sonbhadra district of Uttar Pradesh, India. Conjugate pairs of kink bands are confined within the laminated sandstone and are present half km west of Newari near the confluence of a tributary with the Son river. The conjugate kink bands are plunging at 130 and 360 in SE (S580E) and NE (N560E). This shows that ephemeral compressional stress regime was responsible for the development of conjugate set of kink bands. The stress axis would have been oriented from NE-SW direction. A major fault F1 passes through the glauconitic sandstone in the west of the Newari village. This fault is a reverse fault and strikes at N25ºW - S25ºE. Another fault F2 oblique to F1 passes in the direction N70ºE-S70ºW. In view of the fact that the kink bands are confined within the laminated sandstone, it is inferred that they have been formed as a result of penecontemporaneous deformation and suggest seismic activities that might have occurred around 1080±40 Ma ago as a result of activation of the faults present in the Newari area of the Sonbhadra district, Uttar Pradesh, India those may be companion faults of the Son-Narmada Fault system.