Geologic Map of the Twin Buttes 7.5' Quadrangle, Pima County, Arizona, v. 2.0
Open-Source version of gisdata
KeywordsArizona Geological Survey Digital Geologic Maps
Twin Buttes mine
digital geologic map
Basin and Range Province
Upper Bolsa Formation
hydrothermally altered rock
Mission Mine Complex
MetadataShow full item record
CitationRichard, S.M., Spencer, J.E., Youberg, A., and Johnson, B.J., 2019, Geologic Map of the Twin Buttes 7.5' Quadrangle, Pima County, Arizona: Arizona Geological Survey Digital Geologic Map DGM-31, version 1.1, map scale 1:24,000.
PublisherArizona Geological Survey (Tucson, AZ)
DescriptionThis geologic map of the Twin Buttes 7.5' quadrangle, located south of Tucson in southern Arizona, includes both bedrock and surficial mapping. The map shows the 2120 level in the Twin Buttes mine, along with geology mapped by Anaconda geologists that are now buried beneath rock heaps around the mine. Access to the now inactive Twin Buttes mine was not obtained during the current mapping effort. The most prominent feature of Paleozoic and Mesozoic units in the Twin Buttes area is the northwest-trending alignment of lithologic contacts. In outcrops on Twin Buttes and hills to the west, layering in marbles and rare relict bedding in clastic units are sub parallel to this trend except for local irregularities. A northwest-trending fault, parallel to the trend of lithologic units, is intruded by Ruby Star Granodiorite east of Twin Buttes (UTM 494300N, 3531000E). In the Twin Buttes level 2120 map, a short segment of a northwest-trending fault separates Horquilla Limestone from Proterozoic granite. A third significant, northwest-trending fault is inferred within the porphyry intrusion in the Twin Buttes mine, south of the Twin Buttes fault. The stratigraphically highest unit intruded by the porphyry southwest of the fault is the Concha Limestone, but on the northeast side of the intrusion, Earp and possible Horquilla formation are intruded. These relations require that the intrusion is inserted along a fault. In all three cases, the northwest-trending faults have younger rocks to the southwest and older rocks to the northeast. One 1:24,000 scale map sheet with cross-section.
RightsArizona Geological Survey. All rights reserved.
Collection InformationDocuments in the AZGS Document 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 email@example.com.
North Bounding Coordinate32
South Bounding Coordinate31.875
West Bounding Coordinate-111.125
East Bounding Coordinate-111
Showing items related by title, author, creator and subject.
Geologic Map of the Mount Fagan 7.5' Quadrangle, Eastern Pima County, Arizona, v. 2.0Ferguson, C.A.; Youberg, A.; Gilbert, W.G.; Orr, T.R.; Richard, S.M.; Spencer, J.E. (Arizona Geological Survey (Tucson, AZ), 2019)
Geologic Map of the Southern Part of the Vail 7.5' Quadrangle, Eastern Pima County, Arizona, v. 2Richard, S.M.; Spencer, J.E.; Ferguson, C.A.; Youberg, A. (Arizona Geological Survey (Tucson, AZ), 2020)
Stratigraphy and Sedimentology of the Bisbee Group in the Whetstone Mountains, Pima and Cochise Counties, Southeastern ArizonaDickinson, W. R.; Archibald, Lawrence Eben; Schreiber, Joseph F., Jr.; Flessa, Karl; Archibald, Lawrence Eben (The University of Arizona., 1982)The Aptian-Santonian(?) Bisbee Group in the Whetstone Mountains comprises 2375 m of clastic sedimentary rocks and limestones. The basal Glance Conglomerate unconformably overlies the Pennsylvanian-Permian Naco Group. It consists of limestone conglomerates which were deposited in proximal alluvial fan environments. The superadjacent Willow Canyon Formation contains finer grained rocks which were deposited in the distal portions of alluvial fans. The lacustrine limestones in the Apache Canyon Formation interfinger with and overlie these alluvial fan facies. The overlying Shellenberger Canyon Formation is composed mostly of terrigenous rocks derived from westerly terranes. This formation contains thick sequences of fluvio-deltaic facies as well as a thin interval of estuarine deposits which mark a northwestern extension of the marine transgression in the Bisbee -Chihuahua Embayment. The youngest formation (Upper Cretaceous?) in the Bisbee Group, the Turney Ranch Formation, consists of interbedded sandstones and marls which were deposited by fluvial and marine(?) processes.