ANALYSIS OF AEROMAGNETIC ANOMALIES OVER THE CENTRAL PART OF THE NARMADA-SON LINEAMENT

The Narmada-Son lineament (NSL) forms a major tectonic feature on the Indian subcontinent. The importance of this lineament lies in its evol ution as well as its tectonic history. The lineament seems to have bee n active since Precambrian times. In order to understand the history o f its evolution, it is necessary to know what igneous activity has bee n taking place along this lineament, and how the Deccan trap volcanics , which cover large areas along this lineament, have erupted. For the study of this problem an analysis of the aeromagnetic anomaly map lyin g between 76-degrees 15' to 77-degrees 30'E and 21-degrees 45' to 22-d egrees 50'N has been carried out. Four different profiles (B1'B1, B2'B 2, B3'B3, and B4'B4) have been drawn in N-S direction over this area a nd interpreted in terms of the intrusive bodies present within or belo w the surface of Deccan trap exposures. Inversion and forward modellin g techniques have been adopted for interpretation purposes. An analysi s of frequency spectra along the profiles has also been carried out to estimate the average depth of the different magnetic bodies. These re sults have been correlated with the available geological information. It has been found that most of the small wavelength anomalies are caus ed by dyke-like bodies within or below the Deccan trap at a depth of l ess than 0.5 km.