Deformation and Tectonic History of Punagarh Basin in the Trans-Aravalli Terrane of North-Western India

Abstract

Trans-Aravalli terrane in the NW India is represented by Neoproterozoic volcano-sedimentary succession of Punagarh Basin that unconformably overlies deformed and metamorphosed basement rocks of Sojat Formation. The basement rocks were deformed into upright inclined folds with parallel to chevron geometry. The axial plane cleavages were developed showing variation in trend from NE-SW to ENE-WSW and this variation was due to late generation open folds. The folded rocks were superimposed by normal as well as strike faults which vary from planar to listric geometry. Due to block rotation roll over antiforms with complimentary synforms were developed. Erinpura granites and Malani Igneous Suite intruded Sojat Formation. Punagrh Group is subdivided into three Formations namely Bambholai Formation, Khamal Formation and Sowaniya Formation represented by quartzite, shale and bimodal volcanics. The lithological sequence suggests a deposition in a continental rift environment where volcanics were associated with shelf water facies. Normal as well as strike slip faults were developed in the sediments and are syn-kinematic to deposition. While the normal faults strike NE-SW direction the strike slip faults are in WNW-ESE direction. Small scale roll overs, drag folds and flanking structures are associated with normal faults while en-echelon arrays of quartz veins are associated with the strike slip faults. The paleostress tensor analysis of small scale faults suggests a NW-SE extension created normal faults while the strike slip faults were produced from a NNW-SSE compression.