HR: 16:30h
AN: G44A-03 INVITED     [Abstracts]
TI: Constructing Full Spectrum Potential-field Anomalies for Enhanced Geodynamical Analysis Through Integration of Surveys From Different Platforms
AU: * Ravat, D
EM: ravat@geo.siu.edu
AF: SIUC, Dept. of Geology, Carbondale, IL 62901-4324 United States
AB: To complement multi-disciplinary regional geophysical projects such as EarthScope (USA), a significant opportunity exists in potential-fields for improving the characterization of density and magnetic variations inside the Earth and constraining geodynamical parameters such as variation of temperature and strength of the lithosphere. However, these contributions require complete and accurate anomaly spectrum (a few km to the longest possible anomaly wavelength). Recent and continuing upgrade of North American gravity and magnetic anomaly maps, Australian magnetic map, and on-going compilation of the world digital magnetic anomaly map reflect the recognition of defects in present databases and importance of the full spectrum anomaly field in the interpretation of regional geology. In magnetics, problems in adequately collected data stem from variety of sources ranging from defects in secular variation of IGRF models and the consequent need to warp local magnetic surveys to accomplish continental compilations to lack of accurate methods to compare and integrate data sets from disparate platforms (ground, marine, aeroplane, balloon, satellite). Methods have been developed in the last decade (Sabaka et al., 2002, Geophys.J.Int., 151, 32-68; Ravat et al., 2002, Geophysics, 67, 546-554; Ravat et al., 2003, The Leading Edge, 22, 784-785) for processing, comparing, and integrating these disparate data that show that when properly reduced data sets are combined with appropriate methods, it is possible to create full spectrum anomaly fields in many situations. Yet, challenges remain in the intermediate wavelength (150-500 km) magnetic anomaly band over most of the world, especially where original observation parameters are not available. There are similar challenges in the integration of the gravity field. Long wavelengths of the potential-fields are critical for interpreting deep crustal magnetization and even deeper density variations, constraining the temperature field and strength variations of the lithosphere, correctly isolating regional geologic variations from the regional effects such as continent-ocean contrasts, and also isolating core field from lithospheric magnetic fields.
DE: 8130 Heat generation and transport
DE: 1234 Regional and global gravity anomalies and Earth structure
DE: 1236 Rheology of the lithosphere and mantle (8160)
DE: 1532 Reference fields (regional, global)
DE: 1545 Spatial variations (all harmonics and anomalies)
SC: Geodesy [G]
MN: 2004 AGU Fall Meeting