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Mineral resources of the Swansea Wilderness Study Area, La Paz and Mohave counties, Arizona
| Content Provider | Semantic Scholar |
|---|---|
| Author | Tosdal, Richard M. Eppinger, Robert G. Blank, Horace Richard Knepper, Daniel H. Gallagher, Austin J. Pitkin, James A. Jones, Stephanie L. Ryan, George S. |
| Copyright Year | 1990 |
| Abstract | The Swansea Wilderness Study area (AZ-05~01 SA) lies in the Rawhide and Buckskin Mountains, west-central Arizona, about 20 mi east of Parker, Ariz. At the request of the U.S. Bureau of land Management, mineral surveys of approximately 15,755 acres were done by the U.S. Geological Survey and U.S. Bureau of Mines to assess its mineral resources (known) and mineral resource potential (undiscovered). In this report, the study area refers to only that part of the wilderness study area for which a mineral survey was requested by the U.S. Bureau of land Management. Mining and prospecting activity has o·ccurred in or adjacent to the Swansea Wilderness Study Area in the Swansea, Mesa, and Owens mineral districts. Copper, silver, and lesser quantities of gold, lead, zinc, and manganese have been produced from mines in these districts. Metals have been recovered from deposits along the Buckskin-Rawhide detachment fault and subsidiary highand low-angle normal faults (Swansea and Mesa mineral districts) and along northwest-striking highangle faults that cut mylonitic gneiss and schist (Owens mineral district). There are no identified resources in the study area. Moderate and high potential for base and precious metals (copper, lead, zinc, gold, silver) in the study area exists in areas along northwest-striking high-angle faults in the northern part of the study area, along highand low-angle faults in the lower-plate terrane south of the Bill Williams River, and along the Buckskin-Rawhide detachment fault and its upperplate faults on the south, northeast, and northwest margins of the area; low potential exists in the south-central area. Part of Black Mesa in the northern part of the study area has high potential for manganese, whereas an area in the southeast Manuscript approved for publication, August 20, 1990. corner of the study area has low potential for manganese. Areas of low potential for uranium and vanadium are found in the Tertiary sedimentary and volcanic rocks in the northern and southeastern parts of the study area. The entire Swansea Wilderness Study Area has no resource potentia I for oil and gas and sand and gravel. Character and Setting The Swansea Wilderness Study area (AZ--Q50--015A) covers approximately 15,755 acres in La Paz and Mohave Counties, west-central Arizona~ about 20 mi east of Parker, Ariz. (fig. 1). The study area straddles the Bill Williams River, which divides the Rawhide Mountains on the north from the Buckskin Mountains on the south. Elevations in the study area range from about 600ft along the Bill Williams River to 1,600 to 1,700 ft at the highest point on Black Mesa, north of the river, and at the crest of the Buckskin Mountains south of the river. The study area lies in the northwest-trending belt of metamorphic core complexes in west-central Arizona (Rehrig and Reynolds, 1980). In these complexes, mid-crustal and deeper rocks were tectonically transported to the surface along shallow-dipping nonnal faults or detachment faults during a period of extensional tectonism in the late Oligocene and Miocene (Davis and others, 1980; Spencer and Reynolds, 1986; Davis, 1988) (see appendixes for geologic time chart). The detachment fault in the study area is the Buckskin-Rawhide detachment of Spencer and Reynolds (1986, 1989), which crosses the northern part of the study area and crops out discontinuously along the south border of the study area (fig. 2). The detachment fault divides the 1 La Paz County was created by the Arizona Legislature effective January 1, 1983, from what was the northern half of Yuma County. Mineral Resources of the Swansea Wilderness Study Area, La Paz and Mohave Counties, Arizona C1 bedrock geology of the area into two parts, an extended and highly faulted upper plate of Proterozoic, Paleozoic, Mesozoic, and Tertiary metamorphic, igneous, and sedimentary rocks, and a lower plate of Tertiary mylonite and mylonitic gneiss that was derived from Proterozoic, Paleozoic, Mesozoic, and Tertiary metamorphic, igneous, and sedimentary protoliths. Mylonitic deformation in the lower plate is considered to be a deeper level expression of, and slightly older than, brittle extensional faulting along the detachment fault and its upper plate (Davis, 1983; Spencer and Reynolds, 1986; Howard and John, 1987; Davis and Lister, 1988). Sedimentary and volcanic rock deposition accompanied extension, and these rocks now crop out in the highly faulted upper plate terrane (Davis and others, 1980; Spencer and Reynolds, 1989). During the last stages of, or after the end of, the extensional deformation, high-angle faults cut the detachment terrane. Extensional deformation was followed by basaltic and locally silicic volcanism in the middle and late Miocene (Suneson and Lucchitta, 1983). These volcanic rocks are interbedded with locally derived sedimentary rocks that filled depressions within the extended terrane. The extensional fault system, associated syntectonic |
| File Format | PDF HTM / HTML |
| DOI | 10.3133/ofr90521 |
| Alternate Webpage(s) | https://pubs.usgs.gov/bul/1704c/report.pdf |
| Alternate Webpage(s) | https://doi.org/10.3133/ofr90521 |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
