Regional gravity and magnetic anomalies in the eastern Snake River Plain, Idaho

Journal of Research of the U.S. Geological Survey
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Abstract

Over the eastern Snake River Plain, the Bouguer gravity anomaly and the magnetic intensity are, in general, high. In detail, both the gravity and the magnetic anomalies are a complex of highs and lows, in contrast to the simpler anomalies over the western Snake River Plain. The broad gravity high associated with the eastern Snake River Plain cannot be produced by a dense mass at shallow depth under the plain, but must be produced either by a deep feature under the plain or by a broader, shallower feature extending well beyond the plain. The high could be produced by a thinning of the crust under the plain by 4.5 to 7 kilometers. The data suggest that the Cenozoic rocks of the plain are underlain by rocks that have density and magnetization similar to the density and magnetization of the pre-Cenozoic rocks north and south of the plain. The data do not suggest rifting of the upper crust such as is inferred for the western Snake River Plain. The plain is in approximate isostatic equilibrium with adjoining regions to the north and south and thus contrasts with the adjoining areas where the basin-and-range topography is not in isostatic equilibrium. The local gravity anomalies on the plain are probably produced by variations in the thickness of Cenozoic rocks, but the wavelength of the anomalies is about twice that of the basin-and-range structural features in areas adjoining the plain. The gravity expression of basin-and-range structural features does not extend far onto the plain. Magnetic anomalies on the plain are produced by Cenozoic volcanic rocks.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Regional gravity and magnetic anomalies in the eastern Snake River Plain, Idaho
Series title Journal of Research of the U.S. Geological Survey
Volume 6
Issue 5
Year Published 1978
Language English
Publisher U.S. Geological Survey
Publisher location Arlington, VA
Description 10 p.
First page 553
Last page 562
Country United States
State Idaho
Other Geospatial Snake River Plain
Online Only (Y/N) N
Additional Online Files (Y/N) N
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