Modelling of a magnetic anomaly in east Ganga basin and its implications on the tectonics of the region

摘要

Magnetic data around Muzaffarpur in the eastern part of the Ganga basin display a conspicuous magnetic anomaly in an otherwise relatively smooth magnetic terrain. The anomaly with intense amplitude of about 1500 nT is located at the junction of the west Patna Fault and the Sitamarhi Fault. The low-high axis of this anomaly is oriented at 45E, suggesting that the source possesses remanent magnetism. Magnetic modelling reveals that the source, located at a depth of 4200 m, is polarized at an inclination of 10S and declination of 45E. This implies that the causative source is emplaced when this part of the continent is located 5 south of the equator and is tilted 50E with respect to the present position, describing a moment of the northward journey of the Indian plate after its breakup from Antarctica.