Geologic Map of the Rincon Valley Area, Pima County, Arizona, v. 2.0

The bedrock geology of the map area is dominated by several sets of rock units, as follows: (1) Variably mylonitic granitic and gneissic bedrock at the north flank of the map area forms the Rincon Mountains and the footwall of the Catalina detachment fault. The Catalina detachment fault is a Tertiary, moderately to gently southwest dipping normal fault that has tens of kilometers of top-to-the-southwest displacement (>27.5 km displacement estimated by Dickinson, 1991). (2) Complexly deformed Paleozoic carbonate and siliciclastic strata and Proterozoic granitoids and diabase are exposed at the southwestern foot of the Rincon Mountains and above the Catalina detachment fault. (3) The Oligo-Miocene Pantano Formation, which consists of variably tilted conglomerate, sandstone, mudstone, and andesitic lava flows. Farther to the southwest, the Empire Mountains consist of (4) structurally complex Proterozoic and Paleozoic rocks of diverse composition, and (5) a deformed, regionally southeast dipping sequence of siliciclastic sedimentary rocks of the lower Bisbee Group. In some extensive areas, Quaternary stream incision has uncovered unconsolidated to poorly consolidated clastic sedimentary deposits that are typically mantled by colluvium. These deposits are shown on plate 1 as Tertiary and Quaternary deposits, undivided.