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Structural Relations Determined from Interpretation of Geophysical Surveys: Woody Mountain Well Field, Coconino County, Arizona

From the Proceedings of the 1974 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 19-20, 1974, Flagstaff, Arizona / The Coconino Sandstone of Permian age is the principal aquifer for the Woody Mountain well field, a source of municipal water for the City of Flagstaff. Wells of highest yield are located where the frequency of occurrence of faults is greatest and where the principal aquifer is down-faulted. The locations and displacements of all but the most prominent faults cannot be determined using conventional geologic mapping techniques because relatively undeformed Late Cenozoic basaltic lavas cover the faulted Paleozoic rock terrain. Approximately 3,500 feet of Paleozoic sedimentary rocks, which have little magnetic effect and which have a density of approximately 2.4, comprise most of the stratigraphic section in the well field. The basalt cover is strongly reversely magnetized and has a density of approximately 2.7. Changes in thickness of the basalt cover cause changes in the geomagnetic and gravitational field strength. Analysis of data from geomagnetic and gravity surveys was used to delineate boundaries and thicknesses of blocks of basalt which fill down -faulted areas. The correlation coefficient (r² = 0.96) for plots of known thicknesses of basalt versus complete Bouguer anomaly supports use of gravity data to estimate displacement of down -faulted blocks.

Identiferoai:union.ndltd.org:arizona.edu/oai:arizona.openrepository.com:10150/300420
Date20 April 1974
CreatorsScott, Phyllis K., Montgomery, E. L.
ContributorsNorthern Arizona University
PublisherArizona-Nevada Academy of Science
Source SetsUniversity of Arizona
Languageen_US
Detected LanguageEnglish
Typetext, Proceedings
RightsCopyright ©, where appropriate, is held by the author.

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