Structural pattern of Holenarsipur Supracrustal Belt, Karnataka, India as observed from digitally enhanced high-resolution multi-sensor optical remote sensing data aided by field survey

Abstract

The Holenarsipur Supracrustal Belt of Karnataka, India is known to represent one of the most structurally complex precambrian Supracrustal Belts. In this work, digital enhancement of multi-spectral satellite data, merging of multi-sensor satellite data integrating the advantages of multi-spectral Landsat TM data with higher spatial resolution IRS PAN data and fusion of satellite data with ancillary data, such as topographic relief variation, were attempted to highlight the regional structural features of the area. Regional structural features such as mesoscopic fold closures, folded layers in rocks, fractures, faults, regional foliations, foliation triple junctions and shear foliations have successfully been delineated from the enhanced and fused satellite imagery.The digital terrain model (DTM) of the area draped over by enhanced satellite imagery aided by supplementary field observations helped in visualizing 3D disposition of the Supracrustal Belt in relation to the surrounding gneissic complex and circular to elliptical granitic masses. Basement nature of the gneissic complex and intrusive nature of the granitic masses are understood from this study.Subsequently, field survey has been carried out to map the regional geological features and to understand the spatial distribution of planar and linear structural elements in the area. The observations from field survey were then compared with that obtained from the satellite imagery. In this study, it is observed that for mapping regional-scale structural features, multi-spectral TM data, higher spatial resolution PAN data and terrain topography after enhancement and fusion are comparable to field observation. In cases, they are found to provide supplementary regional-scale information to field mapping. However, they lag behind field mapping in deciphering macro-scale structural information due to their inherent limitation to spatial resolution.The regional-scale and macro-scale structural information derived from enhanced and fused satellite data products and field survey deciphers the broad structural pattern of the Supracrustal Belt. An overall structural uniformity over the Supracrustal Belt from south to north is inferred from this study. An attempt has been made to analyze the structural pattern of the belt in the light of available information.