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New digital magnetic anomaly database for North America

U.S. Geological Survey, Denver, Colorado, U.S.

Mark Pilkington

Geological Survey of Canada, Ottawa, Canada

Alejandro Cuevas and Israel Hernández

Consejo de Recursos Minerales, Hidalgo, Mexico

Jaime Urrutia

Universidad Nacional Autónoma de México, Mexico DF, Mexico

Corresponding author: cfinn@musette.cr.usgs.gov

The first 20% of the full text of this article appears below.

The Geological Survey of Canada (GSC), U.S. Geological Survey (USGS), and Consejo de Recursos Minerales of Mexico (CRM) are compiling an upgraded digital magnetic anomaly database and map for North America. This trinational project, expected to be completed by late 2002, will replace the Magnetic Anomaly Map of North America constructed as part of the Geological Society of America's Decade of North American Geology (DNAG) program. The U.S. component of the DNAG map consists of a digitized version of the first analog magnetic map for the U.S. produced by Zietz (1982). The Canadian part is based on a 2-km grid that covers 70% of the country's landmass. Unfortunately, no Mexican data were included in the DNAG map.

Although this first continentwide map was a significant achievement, it is generally unsuitable for addressing geologic problems that require digital data processing. Indeed, for the U.S. portion, the analog techniques used to assemble the disparate data sets do not adequately reconcile the wide range of individual survey specifications. This resulted in substantial inconsistencies that became more obvious after the data had been digitized. As a result of these past compilation problems in the United States and recent major improvements in data coverage, primarily in Canada and Mexico, compilation of a new digital database covering North America is clearly warranted.

	Data sources

 
Canada has conducted systematic aeromagnetic mapping since 1947, with centralized quality control at GSC. Constant survey specifications have been maintained for 70% of land coverage; data were collected with a line spacing of 0.8 km at a height of 0.3 km. Higher-resolution surveys with line spacing as close as 0.2 km and regional surveys over sedimentary basins with spacing as large as 3 km have also been flown (Figure 1). Approx-imately 20% of the data was digitally acquired; the rest was digitized . . . [Full Text of this Article]