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Geologic interpretation of an aeromagnetic map of the west-central Columbia Plateau, Washington and Oregon

Open-File Report 76-51
By: , , and 
https://doi.org/10.3133/ofr7651

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Abstract

A low altitude, total intensity aeromagnetic map of the ?west-central Columbia Plateau, underlain principally by the Yakima Basalt,. shows Positive and negative anomalies that stand out from a moderate intensity .background reflecting .interbedded flows of normal and reversed magnetic polarity. One set of anomalies is related to anticlinal ridges, nother follows the traces of known or inferred faults, and a third set coincides with a swarm of feeder dikes for the Ice Harbor flows of Swanson and others (1975b), the youngest unit of basalt in the area. A fourth set of narrow, sinuous anomalies is related to flows that filled ancient valleys during the late stage of Yakima volcanism. The magnetic map suggests that the Ice Harbor dike swarm is offset by left-lateral strike-slip displacement along the Rattlesnake-Wallula fault, a segment of the Olympic-Wallowa lineament. The aeromagnetic map is of great help in delineating the extent of the dike swarm, mapping the ancient drainage system, and understanding the structural history of this part of the Columbia Plateau.

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Publication type Report
Publication Subtype USGS Numbered Series
Title Geologic interpretation of an aeromagnetic map of the west-central Columbia Plateau, Washington and Oregon
Series title Open-File Report
Series number 76-51
DOI 10.3133/ofr7651
Year Published 1976
Language English
Publisher U.S. Geological Survey
Contributing office(s) Volcano Science Center
Description Report: i, 32 p.; 1 Plate: 30.03 × 32.17 inches
Country United States
State Oregon, Washington
Other Geospatial west-central Columbia Plateau
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