Magnetic Anomaly and Model of the Lonar Meteorite Impact Crater in Maharashtra, India

摘要

The ground magnetic field of the Lonar impact crater (Maharashtra State, India) and its surrounding area was measured and studied utilizing 2.5-dimensional potential field modelling. Field data showed the crater depression is associated with a strong circular negative anomaly with an amplitude of more than 1000 nT. The negative anomaly, however, decreases smoothly while moving from south to north. Most of the crater rim exhibits anomalous positive values. Negative anomalies at the rim are seen in the south–southwestern sections and coinciding in the northeastern section with the Dhar valley. Our study shows that most of the anomaly is caused by the topographic effect and a strong SE directed natural remanent magnetization of Deccan Trap basalts, which are the target of the Lonar-creating projectile. The magnetic anomaly of the relatively weakly magnetized impact-produced allochthonous breccia and post-impact sediments is small, being less than 150 nT.