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The AAPG/Datapages Combined Publications Database

AAPG Bulletin


Volume: 67 (1983)

Issue: 3. (March)

First Page: 451

Last Page: 452

Title: Experimental Low-Altitude Aeromagnetic Reconnaissance for Petroleum in Arctic National Wildlife Refuge, Alaska, Using Horizontal Gradients--A Progress Report: ABSTRACT

Author(s): Terrence J. Donovan, John D. Hendricks, Alan A. Roberts, Patricia T. Eliason

Article Type: Meeting abstract


Variations in the earth's Previous HitmagneticNext Hit field arising from areally restricted increased amounts of shallow-buried magnetite over hydrocarbon deposits have been mapped in the Arctic National Wildlife Refuge and elsewhere is northern Alaska. The anomalies have been delineated with a low-flying (90 m; 295 ft) Previous HitmagneticNext Hit horizontal gradiometer mounted on a fixed-wing airplane. Limited data from stable carbon isotope and remanent magnetism measurements of rock cores form the Cape Simpson region strongly suggest that the Previous HitmagneticNext Hit anomalies result from the chemical reduction of iron oxides in the presence of seeping hydrocarbons. Relatively large Previous HitmagneticNext Hit contrast between typical sedimentary rocks and those locally enriched with this epigenetic magnetite results in distinctive high wav -number and low-amplitude total field anomalies. Magnetometers extended from each wingtip and in a tail stinger permit calculation of the resultant horizontal gradient vector relative to the flight path. This calculation provides data for the unmeasured area between adjacent flight lines spaced at 1.5 km (.9 mi), thereby allowing

End_Page 451------------------------------

generation of accurate computer-enhanced images or maps. Problems related to diurnal variations and solar storms at high Previous HitmagneticNext Hit latitude are largely overcome because changes in the total Previous HitmagneticNext Hit field do not significantly affect the Previous HitmagneticNext Hit gradient. Analysis of an experimental survey, covering 4,418 line km (2,745 line mi), suggests that the Marsh Creek anticline in the Arctic National Wildlife Refuge is prospective for oil and/or gas. Additional Previous HitmagneticTop anomalies were also identified. Although the effect of permafrost on epigenetic processes has not been investigated, the data suggest that special purpose aeromagnetic surveying may be a useful and relatively inexpensive way to explore for oil and gas in this hostile environment.

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