Tectonic framework of southern Bastar Craton, Central India: a study based on different spatial information data sets


T. Yellappa, National Geophysical Research Institute (Council of Scientific and Industrial Research), Uppal Road, Hyderabad, 500007, India. E-mail: yellappa_thoti@yahoo.co.uk


We present here a regional tectonic fabric analysis of the southern margin of the Bastar Craton, Central India, obtained from different spatial data sets that include Shuttle Radar Topographic Mission (SRTM), Landsat ETM+ (Enhanced Thematic Mapper) and IRS (Indian Remote sensing Satellite) P6-LISS3, integrated with available geological information, as well as field and microscopic observations. The southern margin of the Bastar Craton exhibits large-scale structures, such as regional-scale folds, major shear zones and associated tectonic fabric affected by strong brittle–ductile deformation. The deformational features are related to large-scale thrusting, regional compression, and episodic igneous activity during the Precambrian, and display a major tectonic control on magmatism and the evolution of a shear zone system. The NW–SE to E–W and NE–SW trending brittle to ductile shear zones traversing the craton display both dextral as well as sinistral displacements. Well-developed kinematic indicators include, sheared quartz veins, tension gashes, rotated porphyroblasts, S–C fabrics, pinch-and-swell structures, sigmoidal foliations and riedel fractures that are well preserved in the basement Sukma–Bengpal supracrustals, as well as in the younger granitoids of the Dongargarh Supergroup. Large-scale well-developed NW–SE trending isoclinal folding in the basement gneisses and major folding in mafic intrusions in the south-western margin and tight, upright doubly-plunging large-scale folds in the eastern margins of the craton represent two major tectonic events. These events can be correlated to large-scale thrusts and suggest an initial N–S compression of the craton followed by E–W thrusting at different intervals during the tectonic evolution of the craton. The occurrence of several NW–SE trending mafic dykes parallel to the shear zones indicate that regional-scale tensile stresses were operating during the Proterozoic, associated with a possible continental rift environment in the centre of the craton. The structural pattern obtained, together with the structures mapped with the coherence of remote sensing images, give significant information and an opportunity to reconstruct the timing, style of deformation and its kinematics in the southern part of the Bastar Craton and provide important constraints on the kinematics of the shear zone system and evolution of the craton. Copyright © 2011 John Wiley & Sons, Ltd.