Arizona Geological Survey
The study area is situated along the southern edge of the Superstition Mountains approximately 40 miles east of the greater Phoenix metropolitan area (Figure 1). Geology is dominated by mid-Tertiary volcanic rocks of the Superior volcanic field (Ransome, 1903), and these rocks depostionally overlie a crystalline basement of early Proterozoic Pinal Schist intruded by middle Proterozoic granitoids. In some areas a relatively thin sequence of the Middle Proterozoic Apache Group occurs along the contact between these two rock types.
The Picketpost Mountain and Iron Mountain 7.5' quadrangles are located east of the Phoenix metropolitan area and are within the Basin and Range physiographic and tectonic province of southwestern North America.
This report presents an assessment of the seismic hazard associated with the Sugarloaf fault, which crosses State Route (SR) 87 near Mesquite Wash in central Arizona. The Sugarloaf fault is a 20 km (12 mile) long, northwest- to north-trending normal fault with displacement down to the east. We conducted a multi-faceted investigation in order to evaluate the late Quaternary behavior of the Sugarloaf fault and assess the seismic hazard associated with it.
One of the fastest growing areas of Arizona is the eastern part of the Phoenix Basin near the communities of Chandler, Gilbert, Mesa, and Apache Junction. Much of this development has occurred on the piedmont near the base of the mountains where little of the surficial geology has ever been mapped. Because this area of the Phoenix Basin will continue to grow in the future, there is a need to understand the nature and distribution of surficial deposits.
Have earthquakes strong enough to rupture the ground surface occurred on faults in central Arizona during the recent geologic past? Could such earthquakes happen in the future? If so, where are they most likely to occur? The Seismotectonics and Geophysics Section of the U.S. Bureau of Reclamation has, during the last 6 years, been working on answering these questions
Horseshoe and Bartlett Dams are located In the Transition Zone of central Arizona. Within this province, faults with evidence of Quaternary activity are widely scattered, and selsmiclty Is low In comparison to other parts of the western United States.
The Tucson 1 ° X 2.0 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.
This report presents the results of a reconnaissance analysis of Quaternary faulting in central Arizona, conducted for the U.S. Bureau of Reclamation. The goal of this study has been to thoroughly delineate locations of possible Quaternary faulting in the area surrounding existing and potential dam sites in central Arizona.
The Mogollon (muh-ge-own) Escarpment of central Arizona is one of the State's spectacular natural attractions, especially when viewed from the rim of its precipitate cliffs.
Probable quaternary faults in Arizona have been mapped by systematic interpretation of aerial photographs, extensive geomorphic field studies, and compilation of previous work. Greatest concentrations of late Quaternary normal faults are found near the Colorado Plateau margin in northwestern and north-central Arizona, with lesser concentrations in central and southeastern Arizona and the Lake Mead area. Late Quaternary faults are rare in southwestern Arizona and none have been recognized in the interior of the Colorado Plateau province in northeastern Arizona.
