Geologic Map of Quaternary and Upper Tertiary Deposits, Tucson 1o x 2o Quadrangle, Arizona
KeywordsArizona Geological Survey Open File Reports
Basin and Range
Little Dragoon Mountains
Coronado National Forest
Santa Cruz River
San Pedro River
Santa Catalina Mountains
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CitationPearthree, P.A., McKittrick, M.A., Jackson, G.W. and Demsey, K.A., 1988, Geologic Map of Quaternary and Upper Tertiary Deposits, Tucson 1o x 2o Quadrangle, Arizona. Arizona Geological Survey Open File Report, OFR-88-21, 1 map sheet, map scale 1:250,000.
DescriptionThe Tucson 1o x 2o quadrangle exhibits a wide variety of basin landforms and late Cenozoic surficial geologic deposits. Several factors contribute to this diversity. The Tucson quadrangle spans the transition between the relatively low ranges and typically undissected basins of south-central Arizona and the higher ranges and typically dissected basins of southeastern Arizona. Dissected basins have been dominated by base-level lowering of axial streams and their tributaries, while undissected basins have had relatively stable base-levels. The higher ranges of the eastern half of the quadrangle receive more precipitation due to orographic lifting of moist air. This Is superimposed on a distinct regional climatic gradient, with increasing annual precipitation and cooler annual temperatures from west to cast across the quadrangle. Lithologies vary dramatically both within mountain ranges and between ranges; in some cases, rock type appears to profoundly affect piedmont evolution. Scale 1:250,000
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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.