Partial Report for Independence Valley fault zone, northern section (Class A) No. 1582a
citation for this record: Sawyer, T.L., Oswald, J.A., Rowley, P.C., and Anderson, R.Ernest, compilers, 1998, Fault number 1582a, Independence Valley fault zone, northern section, in Quaternary fault and fold database of the United States: U.S. Geological Survey website, http://earthquakes.usgs.gov/hazards/qfaults, accessed 05/23/2013 11:34 PM.
|Synopsis||General: This zone of subparallel normal faults includes intermontane bedrock faults within the northern Pequop Mountains and range bounding faults separating the west flank of the range from the basin beneath Independence Valley. The fault extends from east of Holborn south, across Interstate 80, south to Brush Creek. Reconnaissance photogeologic mapping of fault related features and compilation geologic mapping are the sources of data. Trench investigations have not been conducted, but scarp profiles adequate for regression of scarp height against maximum scarp slope angle are reported for the southern section of the fault.|
Sections: This fault has 2 sections. The general movement history and geometry of the fault zone suggest two possible sections. The northern section extends from the north end of the Pequop Mountains southward as range-front, intermontane, and short piedmont faults to about 13 km south of Interstate 80. The southern section extends from near 41? N latitude south to Brush Creek and is expressed almost entirely by west facing scarps on surficial deposits or erosion surfaces along the west base of the range.
|County(s) and State(s)||ELKO COUNTY, NEVADA |
|Physiographic province(s)||BASIN AND RANGE |
|Reliability of location||Good|
Compiled at 1:100,000 scale.
|Geologic setting||This zone of subparallel normal faults includes intermontane faults within the northern Pequop Mountains, relatively continuous range-front faults along west front of the range from east of Holborn south to Brush Creek, and piedmont faults in eastern Independence Valley. Where it is located at the base of the range, it is apparently a major range-front fault separating the Pequops from the basin beneath Independence Valley. Geology of part of the Pequop Mountains of the southern section mapped at 1:24,000 scale by Fraser and others (1983 #4323), but they showed only two faults cutting Quaternary sediments. Most of the Pequop Range consists of Paleozoic sedimentary rocks, but the north part has Tertiary rocks down faulted to the west along the west base of the range.|
|Length (km)||This section is 26 km of a total fault length of 61 km.|
|Average strike||N9°W (for section) versus N5°W (for whole fault)|
|Sense of movement||Normal|
|Dip Direction||W; E|
|Geomorphic expression||The section is expressed by intermontane faults within the northern Pequop Mountains that are associated with low topographic escarpments. Discontinuous faults along the west front of the range juxtapose Quaternary alluvium against bedrock and piedmont faults are marked by short west-facing scarps in eastern Independence Valley (Coats, 1987 #2861; Dohrenwend and others, 1991 #290). dePolo (1998 #2845) reports a maximum preferred basal fault facet height of 146 m (122-171 m).|
|Age of faulted surficial deposits||Early to middle Pleistocene, Quaternary. The range-front faults displace undifferentiated Quaternary alluvium and the piedmont faults displace early to middle Pleistocene alluvium; age interpretations based on photogeologic analysis (Dohrenwend, 1991 #290).|
|Most recent prehistoric deformation||Quaternary (<1.6 Ma)|
|Slip-rate category||Less than 0.2 mm/yr|
|Date and Compiler(s)||1998|
Thomas L. Sawyer, Piedmont Geosciences, Inc.
John A. Oswald, Piedmont Geosciences, Inc.
Peter C. Rowley, U.S. Geological Survey
R. Ernest Anderson, U.S. Geological Survey
|References||#428 Barnhard, T.P., 1985, Map of fault scarps formed in unconsolidated sediments, Elko 1° x 2° quadrangle, Nevada and Utah: U.S. Geological Survey Miscellaneous Field Studies Map MF-1791, 1 sheet, scale 1:250,000.|
#2861 Coats, R.R., 1987, Geology of Elko County, Nevada: Nevada Bureau of Mines and Geology Bulletin 101, 112 p., scale 1:250,000.
#2845 dePolo, C.M., 1998, A reconnaissance technique for estimating the slip rate of normal-slip faults in the Great Basin, and application to faults in Nevada, U.S.A.: Reno, University of Nevada, unpublished Ph.D. dissertation, 199 p.
#290 Dohrenwend, J.C., McKittrick, M.A., and Moring, B.C., 1991, Reconnaissance photogeologic map of young faults in the Wells 1° by 2° quadrangle, Nevada, Utah, and Idaho: U.S. Geological Survey Miscellaneous Field Studies Map MF-2184, 1 sheet, scale 1:250,000.
#286 Dohrenwend, J.C., Schell, B.A., and Moring, B.C., 1991, Reconnaissance photogeologic map of young faults in the Elko 1° by 2° quadrangle, Nevada and Utah: U.S. Geological Survey Miscellaneous Field Studies Map MF-2179, 1 sheet, scale 1:250,000.
#4323 Fraser, G.D., Ketner, K.B., and Smith, M.C., 1983, Preliminary geologic map of the Spruce Mountain 4 quadrangle, Elko County, Nevada: U.S. Geological Survey Open-File Report 83-301, scale 1:24,000.