Analysis of a north-south magnetic profile over the Central Indian Ocean

摘要

Marine magnetic anomalies provide valuable information on the nature and evolution of the oceanic crust, Magnetic profiles aligned along the direction of spreading enable us to calculate the spreading rates of oceanic crusts on which they pass. This can he done with computed profiles assuming the model and magnetic reversal time scale of the earth. In the present study the north-south magnetic profile of 1280 nautical miles extending from 15 degrees 30'S, 77 degrees E to 6 degrees N, 79 degrees E in the Central Indian Ocean is analysed. The profile runs between the 76 degrees 30'E and 79 degrees E Fracture Zones passing over part of the Australian plate, the Central Indian Ocean deformation zone and part of the Indian plate along the Comorin Ridge. The analysis shows that the profile has a continuous sequence of prominent age anomalies from 22 to 34 N. Australian plate and deformation zone segments have well preserved continuous age anomalies from 22 to 33 and thus their spreading rates are calculated. The results show that the profile is characterized by sets of anomalies with varied spreading rates, anomalies 23-30 having higher values compared to the rest. The spreading rate of anomalies 22-27 is 7.8 cm/yr whereas for anomalies 27-30 it is 10.3 cm/yr. Anomalies 30-33 have a moderate spreading rate of 4.6 cm/yr. Another interesting feature is that the profile has the characteristic edge-effect anomaly on the segment over the Indian plate indicating the oceanic-continental crust boundary. [References: 31]