338000 339000 340000 341000 342000 343000 344000 345000 346000 347000 348000 349000 350000 112°45'0"W 112°42'30"W 112°40'0"W 112°37'30"W Geologic map of the Wickenburg N N " " 0 ' 0 ' 0 0 ° ° Younger alluvial deposits have little to no soil development, retain the original grey or brown color of the alluvial sediment, Tf Xg Kgd 4 4 Qy2 Tf Qi Qi Qy2 3 3 A' Qi3r Xsg 30 65 7 ½' Quadrangle, and no carbonate accumulation. Clasts in these deposits have no weathering rinds or surface patinas and thus appear Tbu 35 Qy3 Qi Xsg Xg Kd Kgd brighter and fresher than older clasts. Young alluvial surfaces often retain original depositional characteristics such as bar Tbu 0 80 Qy2 Kd Tbu 86 Tf 0 and swale. Conversely, older alluvial deposits have better-developed soils that appear orange to red in color, with soil Trs 60 0 Qi Qi 80 3 6 Maricopa and Yavapai County, Tcs Kgd 85 horizons reflecting clay and carbonate accumulation. Clasts on older alluvial deposits often exhibit darkened weathering 7 3 0 65 Tf Tf rinds or rock varnish, and thus appear darker on the ground and in aerial photographs. Preserved alluvial surfaces may be 0 Tf Xg Trs 0 Qy3 Qy1 3 Kd 9 Qi smooth and flat (Qi3), becoming more rounded and coarser with age (Qi2). The oldest alluvial surfaces (Qi1 and Qi2) are 6 Trs Xg Arizona 7 Qi3r 25 3 Qi2 Qy1 70 often eroded, well-rounded ridges with degraded soil preservation and carbonate horizon exposed and eroded into Qy3 Qy2r Trs 65 Tbl 55 Tf Tf 65 colluvial slopes. These surfaces appear white on aerial photos due to widespread exposure of the carbonate horizon, 28 Ts Qy3 although underlying material remains unconsolidated and relatively non-cemented. Alluvial deposits sourced from granitic Qy2r 35 80 75 Tcs 60 Kgd Trs Xg Tbu Tf Xg Xg parent material exhibit very red, clay-rich surfaces with mature B horizons and clay-coated clasts. Exposures of well- Trs Kgd Tbl 55 Sheet 1 of 2 cemented older alluvium are present along active channels and within younger, unconsolidated alluvium in the middle and 70 65 Tbl 15 80 Xg Tf Kgd Tf distal piedmont. Qy3 Tdf Qi2 Tf Qi Tbu Xg Kd Trs Kgd Tts 0 Hassayampa River deposits are confined to relatively narrow reaches of bedrock and basin-fill units across the Qy2 12 Kgd 0 55 Qi 0 Kd Kgd 60 75 2 Wickenburg quadrangle. River deposits consist of channel, flanking terraces, and well-vegetated terraces within a few 11 Qy3 6 55 Tf 7 3 meters above the floodplain. The modern floodplain is incised into early Holocene and Pleistocene river terrace straths 0 Brian F. Gootee, Joseph P. Cook, 0 Tf 0 80 atop bedrock. Active alluvial fan and sheetflow deposits from tributaries along the Hassayampa River are commonly 2 Kgd Tf Qi 6 Qi2 55 Qi eroded away by the more active river. Older intermediate-age Pleistocene river deposits are relatively thin and strathed on 7 Kgd Kgd 3 Stephen J. Reynolds, Michael J. Grubensky, Qi2 Tf bedrock and basin-fill several 10’s of meters above the modern river, and near the river corridor are commonly intermixed Qi2r Qi3r Kgd and subsequently overlain by intermediate-age tributary deposits. East of the modern river, the oldest Hassayampa River Qy1 5 deposits in the quadrangle (Qi1r) are capped by intermediate-age tributary deposits (units Qi2 and Qi3). Qi1r deposits Tbu and James A. Stimac Qy3 Kgd Tf Tlb Tc appear to have been constrained by bedrock paleotopography and alluvial fans near their axis of deposition near the Qi Kgd Trs modern river corridor, and in several places east of the river (see cross-sections CC’ and DD’). These deposits are Qy2r Xg Arizona Geological Survey spectacularly exposed in a roadcut along Highway 60 between San Domingo and Ox washes. Ancestral river deposits Qi2r 5 Tif Kgd Tif Xg aggraded several 10’s of meters across the mapping area and subsequently shifted west to its modern position before Tia Qy 0 Tf 55 0 Qy2 Tf 0 downcutting. Tributaries from the Wickenburg Mountains followed the river prior to downcutting and subsequently became Kgd 1 Tlb Tc 6 Digital Geologic Map 131 (DGM-131) 5 Tst 7 superimposed across underlying bedrock units, forming numerous slot canyons cut into bedrock and alluvial deposits 3 0 Qy1r Qi2 Trs Kgd 0 65 35 further up the piedmont. 0 1 Qi 35 40 Xg 6 Qy1 Qi2 Tbl Xg 7 Tia 3 Qi2 Xg Qi3 Qy1 Qy1 15 Citation for this map: Bedrock Geology Xam Qi Kgd Xg Gootee, B.F., Cook, J.P., Reynolds, S.J., Grubensky, M.J., and Stimac, J.A.,2021, Geologic map of the Wickenburg 7 ½' Bedrock within the Wickenburg quadrangle is exposed in the dissected hills and valleys in the Vulture Mountains terrain, Trs 70 Qy3 Qy 70 Quadrangle, Yavapai County, Arizona: Arizona Geological Survey Digital Geologic Map DGM-131, scale 1:24,000, 2 and in inselbergs, linear ridges, and in narrow washes that dissect the piedmont from Wickenburg Mountains. Bedrock 45 sheets. outcrops consist of Early Proterozoic metamorphic and igneous rocks, Cretaceous igneous intrusions, and extensive mid- Qy1 Trs Qi3 Trs Tf Cenozoic volcanic and hypabyssal, and associated terrestrial rocks. These bedrock units are extensively cross-cut by Qi3 Qy3 70 Qy2 Kg Qy1r Tbu Xg This geologic map was funded in part by the USGS National Cooperative Geologic Mapping Program under StateMap multiple generations of faults and hypabyssal intrusions, moderate to steeply tilted against low-angle faults and 50 Tf 0 Trs Tf Tf 0 award number G18AC00298, 2018. The views and conclusions contained in this document are those of the authors and juxtaposed with older Cretaceous and Proterozoic units. The upper part of the mid-Cenozoic volcanic sequence consists Qy2 0 Qy1 Tf Qi3 0 6 should not be interpreted as necessarily representing the official policies, either expressed or implied, of the U.S. of moderately to loosely consolidated basin-fill fanglomerate and gravels, sand and silt deposits that are progressively Qy2r Qi3 7 60 65 3 0 Qy1 Qi3 85 Xg Government. less-tilted and generally less-consolidated, up stratigraphic section (fanning-dip sequence). Bedrock and basin-fill units 0 Qi3 Tf 0 Qy1 Tbl were mapped in detail by Grubensky (1989), Grubensky and others (1987) and Stimac and others (1987). 0 Tbl Tf 60 Tf 6 d Qy1 Qy1 Qy2 75 7 Qy Introduction 3 Tbl Trs Xg Basin fill deposits are generally non-deformed and gently dipping towards the modern valley. Basin-fill units mapped in Qi3r Tbu Tf Qi3 85 Trs 75 Xam This geologic map is one of a series of four 7 ½’ quadrangle maps (AZGS DGM-131 through 134; Wickenburg, Sam this study were differentiated into mineral and textural facies where possible. Near major faults basin fill deposits have 88 Tia Tf Qi3 Qy d Trs Trs Powell Peak, Flores, and Vulture Peak) in the Wickenburg area. New surficial mapping was conducted throughout the 4- steeper depositional tilts, and in some cases are mildly faulted and rotated. Eolian deposits are found intermixed with Qy Qy Qi3r Tbl Tbl 25 Xam quadrangle mapping area and bedrock mapping was compiled from existing geologic maps. Together, these maps basin-fill deposits in close proximity to bedrock-range faults, forming small, isolated sand ramps and dunes too small to Qy2r Xg Xg 40 Qi3 75 85 include detailed surficial mapping of alluvium from the Date Creek, Weaver, Wickenburg, and Vulture Mountains as well map individually. Prior to arrival of the Hassayampa River, field relationships suggest a pre-existing closed basin was not Tcs Tcs Qi3r 15 Trs Tf Qy1r Trs Tf Xg Qi3 Trs 53 Tf as ancestral deposits of the Hassayampa River. The relationships between relict and modern alluvial fan and present, and that streams likely drained from adjacent piedmonts into a low-relief axial valley open to the east and south. Qy3 85 0 Hassayampa River deposits and their positions relative to pre-existing bedrock topography presents a glimpse into the Qi3r 12 Xg 70 0 Qy2 Tf 8 Tf 0 3 9 arrival and development of the modern Hassayampa River system. Acknowledgments 53 Qi3 5 Trs Qi3 7 Kg 70 3 0 Tf Tbl 0 41 Tcs Qy1r N The Wickenburg 7 ½' Quadrangle straddles the boundary between southern Yavapai and northern Maricopa County and Bedrock mapping and unit descriptions was derived from existing geologic maps of the Vulture and Wickenburg 0 N 53 Qi2r Qi2r " " Tcs 40 Tf 9 Qi2 0 0 60 3 5 ' 3 includes the towns of Wickenburg and Morristown, AZ. US Highway 60 passes through the quadrangle from SE to NW. Mountains (Grubensky et al., 1987, Grubensky, 1989, Reynolds et al., 1988, and Stimac et al., 1987). Georeferenced ' A 7 7 7 25 3 Qy1 5 5 ° ° Qi2 The Hassayampa River flows southeast along the highway separating the Vulture Mountains to the southwest and scans of these maps were digitized in ArcMap and adjusted based on new field mapping, observations, and interpretation Qy1 3 3 Qy2r 3 3 Qi3 d 5 5 Trs Tf Qi3 Wickenburg Mountains to the east. The Vulture Mountains are part of a rugged terrain of dissected bedrock hills and of modern aerial imagery. Careful attention to detail was used throughout the digitization process but differences in source Qy1 Trs Xg Qi2 Qy2 Trs Xg 40 Xm valleys in contrast with the extensive alluvial piedmont emanating from the Wickenburg Mountains. Tributaries from both map scale, varying line thickness and legibility of the source map, errors in the georeferenced scan, and possible errors in 26 Qi3 Qy1r areas drain into the Hassayampa River, where incision has exposed axial basin-fill deposits overlain by ancestral the original map can compound and result in errors in this map.