HR: 0800h
AN: GP31A-01    [Abstracts]
TI: Improving the Magnetic Anomaly Map of the United States
AU: * McIndoo, M
EM: mmcindoo@siu.edu
AF: Southern Illinois University Carbondale, Dept. of Geology, Carbondale, IL 62901-4324, United States
AU: Shaw, A
EM: adam1385@siu.edu
AF: Southern Illinois University Carbondale, Dept. of Geology, Carbondale, IL 62901-4324, United States
AU: Batir, J
EM: jbatir33@siu.edu
AF: Southern Illinois University Carbondale, Dept. of Geology, Carbondale, IL 62901-4324, United States
AU: Ravat, D
EM: ravat@geo.siu.edu
AF: Southern Illinois University Carbondale, Dept. of Geology, Carbondale, IL 62901-4324, United States
AU: Milligan, P
EM: Peter.Milligan@ga.gov.au
AF: Geoscience Australia, GPO Box 378, Canberra, Australia
AU: Kucks, R P
EM: rkucks@usgs.gov
AF: U. S. Geological Survey, Box 25046, Denver, CO 80225-0046, United States
AU: Hill, P
EM: pathill@usgs.gov
AF: U. S. Geological Survey, Box 25046, Denver, CO 80225-0046, United States
AU: Hildenbrand, T G
EM: tom@usgs.gov
AF: U. S. Geological Survey, 345 Middlefield Road, Menlo Park, CA 94025, United States
AB: We have improved magnetic anomaly map of the United States using National Uranium Reconnaissance & Evaluations (NURE) aeromagnetic surveys collected during the 1970s. Previous versions of these data processed using IGRF/DGRF do not mesh well at the survey boundaries because of leveling artifacts. Similarly, the U.S. component of the North American magnetic anomaly map has long wavelength errors caused by warping of hundreds of state and local aeromagnetic surveys during the merging process. The main difference in our processing that has allowed us to retain proper base levels is the use of the temporally continuous main field Comprehensive Model (CM4) by Sabaka et al. (2004, GJI, 159, 521-547). The advantage of using the NURE surveys is that most of these surveys have time information and diurnal variation observed with basestation magnetometers is removed from them. Furthermore, we have cleaned the NURE data by removing many spurious values through visual inspection. Some NURE surveys did not have total field values or time information. For these surveys, we reintroduced the IGRF for their approximate date and removed the core field determined by CM4. We compare the results of our processing and improvements with the U.S. aeromagnetic anomaly data prepared by different merging techniques. The improved map is more suitable for regional geologic and geodynamic interpretations.
DE: 1517 Magnetic anomalies: modeling and interpretation
DE: 1545 Spatial variations: all harmonics and anomalies
DE: 9350 North America
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2007 Joint Assembly