Geochemistry of the Laramide igneous suite of the Santa Rita and Empire Mountains, southeastern Arizona
AuthorTrapp, Richard A.
KeywordsGeochemistry -- Santa Rita Mountains (Ariz.)
Geochemistry -- Arizona -- Empire Mountains.
Igneous rocks -- Santa Rita Mountains (Ariz.)
Igneous rocks -- Arizona -- Empire Mountains.
MetadataShow full item record
PublisherThe University of Arizona.
RightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Degree GrantorUniversity of Arizona
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Mountain-front recharge to the Tucson basin from the Santa Catalina Mountains, ArizonaMohrbacher, Carl Joseph. (The University of Arizona., 1984)Ground-water flow from the northern margin of the Tucson basin to the regional aquifer in the center of the basin was studied. The area studied was the eastern half of the Santa Catalina Mountains and adjacent foothills in Pima County, Arizona. Low-permeability sediments of Pliocene age separate the gneissic mountain block from the regional aquifer. A flow-net analysis and ion-balance calculations indicated that recharge from the lowpermeability sediments to the aquifer was approximately 50 ac-ft/hr/mile of mountain front. This is about 1/20 of the recharge from local streams. Analyses of oxygen-18, deuterium, and major ions in the ground water revealed that the fracture-flow system in the gneiss is recharged at both high and low elevations and is not well mixed. Ground-water chemistry also suggested that in some areas, water is flowing up from the gneiss along faults.
Mountain-front recharge from the Santa Rita Mountains to the Tucson BasinMerz, August. (The University of Arizona., 1985)This study analyzes mountain-front recharge from the Santa Rita mountains. Trilinear diagrams, finger-print diagrams, and scattergrams suggest that two types of water recharge the regional aquifer by effluent seepage as Madera Canyon Stream flows onto Madera Canyon fan. One type of water is dominated by calcium and bicarbonate ions, and the other type is dominated by calcium and sulfate ions. Deuterium and oxygen-18 data support these interpretations and indicate that recharge occurs over a broad range of elevations. Furthermore, the isotopic data indicate that the deuterium and oxygen-18 gradients are -3.5 0/00 and -0.4 0/00, respectively, per 1000 foot increase. Evidence is lacking for the presence of deeply circulating waters. Calculations based on a flow-net analysis and a water balance approximate annual mountain-front recharge to be between 200 and 400 ac-ft/yr/mi of mountain-front recharge. Recharge studies from the nearby Santa Catalina mountains estimate recharge to be between 25 and 50 ac-ft/yr/mi of mountain front and present evidence for minor amounts of deep circulation through the mountain block into the basin. The Santa Rita Mountains, significantly, have a more permeable alluvial fan which favors recharge.