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

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 localmore » 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.« less

Authors:
Publication Date:
OSTI Identifier:
6379072
Resource Type:
Journal Article
Journal Name:
J. Res. U.S. Geol. Surv.; (United States)
Additional Journal Information:
Journal Volume: 6:5
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES; 15 GEOTHERMAL ENERGY; IDAHO; GRAVITY SURVEYS; MAGNETIC SURVEYS; DENSITY; GEOLOGICAL SURVEYS; RIFT ZONES; VOLCANIC ROCKS; GEOLOGIC STRUCTURES; GEOPHYSICAL SURVEYS; IGNEOUS ROCKS; NORTH AMERICA; PACIFIC NORTHWEST REGION; PHYSICAL PROPERTIES; ROCKS; USA; 580200* - Geophysics- (-1989); 150201 - Geology & Hydrology of Geothermal Systems- USA- (-1989)

Citation Formats

Mabey, D R. Regional gravity and magnetic anomalies in the eastern Snake River Plain, Idaho. United States: N. p., 1978. Web.
Mabey, D R. Regional gravity and magnetic anomalies in the eastern Snake River Plain, Idaho. United States.
Mabey, D R. 1978. "Regional gravity and magnetic anomalies in the eastern Snake River Plain, Idaho". United States.
@article{osti_6379072,
title = {Regional gravity and magnetic anomalies in the eastern Snake River Plain, Idaho},
author = {Mabey, D R},
abstractNote = {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.},
doi = {},
url = {https://www.osti.gov/biblio/6379072}, journal = {J. Res. U.S. Geol. Surv.; (United States)},
number = ,
volume = 6:5,
place = {United States},
year = {Fri Sep 01 00:00:00 EDT 1978},
month = {Fri Sep 01 00:00:00 EDT 1978}
}