STRUCTURAL DELINEATION WITH GEOPHYSICAL APPROACH IN PARTS OF EASTERN DARWAR CRATON

The aim of a magnetic survey is to investigate subsurface geology on the basis of the anomalies in the earth's magnetic field resulting from the magnetic properties of the underlying rocks. Common causes of magnetic anomalies include dykes, faults and lava flows. The magnetic method involves the measurement of the earth's magnetic field intensity. Typically the total magnetic field is measured. Measurements of the horizontal or vertical component or horizontal gradient of the magnetic field may also be made. Regional total magnetic observations were made over an area of approximately 6744 Sq Km with geologically and tectonically interesting in the eastern part of the Dharwar craton. Usually magnetic field data was displayed in the form of a contour map, but interpretation is often made on profiles. A modern technique is to plot the magnetic data as a colour image (red=high, blue=low and all the shades in between representing the values in between). From qualitative analysis various geological boundaries and tectonic features such as faults and shear zones were identified. Trend characteristics of magnetic lineaments were brought through the magnetic intensity, low pass filter map and tilt derivatives. Quantitative analysis of an area's total spectrum of magnetic responses can produce depth information.