HR: 14:40h
AN: GP23A-05    [Abstracts]
TI: Magnetic Field Studies of the Indian Sub-Continent.
AU: * Rajaram, M
EM: mita@iigs.iigm.res.in
AF: Mita Rajaram, Indian Institute of Geomagnetism, New Panvel,, Navi Mumbai, 410218 India
AU: Anand, S P
EM: anand@iigs.iigm.res.in
AF: Mita Rajaram, Indian Institute of Geomagnetism, New Panvel,, Navi Mumbai, 410218 India
AB: Available aeromagnetic data over India upto 25 degrees north latitude are utilized to derive the magnetic anomalies. Several data gaps are filled using available / published ground and marine magnetic data. All available data are reduced to a common altitude to prepare a composite magnetic anomaly map of the region. The tectonic blocks, the lithological contacts and structures below thick sedimentary cover, suture zones and depth to the bottom of the magnetic crust, which essentially coincides with the Curie isotherm depth, are derived from this map. The magnetic anomalies in the North Eastern region of India forms a very critical part of the data set for understanding the complexities of the tectonics of the Indian sub-continent. However large data gaps in the Bengal basin, ocean region and other regions where magnetic data is not available severely constrict the interpretation. Under these circumstances the high-resolution satellite geopotential data with its global coverage gives an insight into the long wavelength structure. The oceanic lithosphere surrounding India is constantly under stress due to the spreading activity resulting in intense deformation in the region. The thick sediment deposits in the Bay of Bengal mask the underlying crust and pose severe restrictions in constructing the geodynamical history of the region. The high-resolution satellite geopotential data with its global coverage offer the unique opportunity of addressing some of these issues. The oblique subduction of the Indian Ocean lithosphere at the Andaman island arc trench system deserves special attention. The lithospheric model MF3 derived from the CHAMP data reveal interesting features in and around the Andaman region. Using the CHAMP satellite magnetic anomaly map and the satellite derived magnetization map as base, the tectonic structure in the Bay of Bengal and in particular the subduction at the Andaman island arc become evident. The SEMM map compares fairly well with the isopach map of the region. Further the available gravity and topography maps of the region help constrain the interpretation. Results of such an analysis will be presented.
DE: 0903 Computational methods, potential fields
DE: 1219 Local gravity anomalies and crustal structure
DE: 1545 Spatial variations (all harmonics and anomalies)
DE: 7218 Lithosphere and upper mantle
DE: 8149 Planetary tectonics (5475)
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2005 Joint Assembly