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dc.contributor.authorPearthree, Philip
dc.date.accessioned2019-10-29T16:58:02Z
dc.date.available2019-10-29T16:58:02Z
dc.date.issued2019-09-01
dc.identifier.citationPearthree, Philip A., Cook, Joseph P., House, Kyle P., 2019, Geologic Map of Clarkdale 7.5' Quadrangle, Yavapai County, Arizona. Arizona Geological Survey Digital Geologic Maps, DGM-138, 1 map sheet, map scale 1:24,000.
dc.identifier.urihttp://hdl.handle.net/10150/634885
dc.descriptionThis map depicts the geology of the Clarkdale 7 ½‘ quadrangle in northwestern Verde Valley. The bedrock geology depicted on the map is slightly modified from DeWitt et al. (2008), and surficial and basin deposit mapping is modified from House and Pearthree (1993). Detailed mapping of deposits associated with the Verde River by Cook et al. (2010) is included in the map as well. This new Arizona Geological Survey Digital Geologic Map (DGM) product integrates all of these data sets and makes them available in a variety of digital formats. The map consists of bedrock geology, a moderately detailed depiction of basin deposits (Verde Formation) and the distribution of piedmont alluvial deposits of different ages and their associated geomorphic surfaces, and a strip of Verde River deposits of various ages. Rough age estimates are assigned to each alluvial unit based primarily on relative topographic position and surface and soil characteristics, with limited numerical age constraints that are discussed below. Geologic structures in the bedrock units other than the principal traces of the Verde Fault are not included in these maps. The following is a summary of the geology of the Clarkdale quadrangle, including the Plio-Quaternary evolution of northern Verde Valley derived in part from mapping in adjacent quadrangles. Bedrock units predominate in the western and northernmost parts of the quadrangle. These rocks consist primarily of Mississippian Redwall Limestone, Pennsylvanian Supai Formation, and Pennsylvanian-Permian Hermit Shale, with smaller outcrops of Devonian Martin Formation, Cambrian Tapeats Sandstone, and Proterozoic metasedimentary and metavolcanics basement. Bedrock is overlain, and locally in fault contact with, Miocene volcanic rocks and associated sediments (probably part of the Hickey Formation), and Verde Formation deposits. Exposures of limestone and fine- to coarse-grained siliciclastic deposits of the Verde Formation are widespread in the quadrangle. The Verde Formation was deposited as normal faulting along the base of the Black Hills dropped the valley down. Some of the highest preserved remnants of Verde Formation deposits are found in the Clarkdale quadrangle, up to ~1380 m above sea level on the south flank of Black Mountain near the north edge of the quadrangle. The age of maximum filling of Verde Valley was ~2.5 Ma based on paleomagnetic stratigraphy (Bressler and Butler, 1978); eroded ridges in the Jerome area are capped with thin remnant alluvial fan deposits that are poorly-preserved vestiges of this period. Subsequent river downcutting apparently has been episodic, with river terraces and piedmont alluvial surfaces graded to them representing intervals of stability or minor aggradation. Multiple early to middle Pleistocene river terraces exist in the valley axis (e.g., Qo1r, Qi1r); we map 3 early Pleistocene river terraces and 3 middle to late Pleistocene terraces; the highest terraces are 90-100 m above the modern river channel, and thus are inset far below the maximum level of Verde Formation deposition. Thus roughly 70% of Verde River downcutting had occurred prior to Qo deposition. The extent of Holocene deposits is quite limited except in the Verde River floodplain and low terraces, and tributary alluvial fans graded to the Holocene river. Splays of the Verde fault zone, which separates the bedrock of the Black Hills from the basin deposits of Verde Valley, In some areas there are clearly multiple fault strands, and there are almost certainly more fault strands that are not exposed. There is, however, no clear evidence of displacement of Quaternary surficial deposits along this part of the Verde fault zone. Flood hazards?
dc.language.isoenen_US
dc.publisherArizona Geological Survey (Tucson, AZ)en_US
dc.relation.ispartofseriesDigital Geologic Mapsen_US
dc.rightsArizona Geological Survey. All rights reserved.en_US
dc.titleGeologic Map of Clarkdale 7.5' Quadrangle, Yavapai County, Arizonaen_US
dc.contributor.departmentArizona Geological Surveyen_US
csdgm.bounding.west-112.125
csdgm.bounding.east112.001
csdgm.bounding.north34.875
csdgm.bounding.south34.75
dc.description.collectioninformationDocuments in the AZGS Documents Repository collection are made available by the Arizona Geological Survey (AZGS) and the University Libraries at the University of Arizona. For more information about items in this collection, please contact azgs-info@email.arizona.edu.en_US
refterms.dateFOA2019-10-29T00:00:00Z


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