Geomatics Approach - Structural Mapping and Automated Lineament Extraction in Parts of Central Tamil Nadu

The area of this study is one of the important places in central part of Tamil Nadu, which contains many ore deposits, plantation fields, and villages. Because of this, study of geological structures (lineaments) is one of the most important factors, which gives indications about the locations of ore deposits, and groundwater movements. Shaded relief images and Landsat 8 are helpful in identifying lineaments in different distinct relief and topography. The method can enhance lineaments at different orientations by simulating topographic illumination under varied light directions. Combining four shaded relief images into a final image leads to enhancing lineaments within the four sun azimuth directions. Two shaded relief images with multi-directional light were created, the first image with the four azimuth angles of the light sources that are 0°, 45°, 90° and 135°, and the second image with the four azimuth angles of the light sources that are 180°, 225°, 270°, and 315°. Both images have been used for automatic lineament extraction using PCI Geomatica software. The extracted lineaments of the first image show that the most automatic lineaments represent positive lineaments; and the automatic lineaments of second image represent negative lineaments of the study area. The directional analysis of the automatically extracted lineament maps have been done with the reference of the fault map of the area. The results verify the similarity in the directional behaviour of the lineaments, the fault lines and the structures measured in the field. The main trends of the extracted lineaments ofboth images are NW-SE, N-S, E-W and NE-SW.