Moab fault and deformation zones (Class B) No. 2476
Last Review Date: 2004-05-01
Compiled in cooperation with the Utah Geological Survey
citation for this record: Black, B.D., Hylland, M.D., and Hecker, S., compilers, 2004, Fault number 2476, Moab fault and deformation zones, in Quaternary fault and fold database of the United States: U.S. Geological Survey website, https://earthquakes.usgs.gov/hazards/qfaults, accessed 12/06/2023 04:52 PM.
Poorly understood late Quaternary deformation related to collapse of the Spanish Valley anticline. As with many other faults in the region, the Moab fault and Spanish Valley faults are probably related to salt dissolution, but may have a tectonic component, thus we classify them as a Class B feature.
Fault ID: Refers to fault number 18-2 of Hecker (1993 #642).
|County(s) and State(s)||
SAN JUAN COUNTY, UTAH
GRAND COUNTY, UTAH
|Reliability of location||
Compiled at 1:250,000 scale.
Comments: Mapped or discussed by McKnight (1940 #6767), Shoemaker and others (1958 #5009), Jones (1959 #4993), Williams (1964 #2789), Woodward-Clyde Consultants (1982, #5025; 1986 #6768), Harden and others (1985 #4988), and Oviatt (1988 #5006), Woodward-Clyde Federal Services (1996 #5027), Doelling and others (2002 #6764), and Hylland and Mulvey (2003 #6766). Mapping from Williams (1964 #2789) and Doelling and others (2002 #6764).
Northwest-trending zone of faulting and warping from collapse of the Spanish Valley anticline from salt dissolution. The Moab fault bounds the western side of the valley and may have a tectonic component. Shoemaker and others (1958 #5009) and Jones (1959 #4993) indicated that the fault may extend below the salt, offsetting pre-Paradox Formation strata.
|Length (km)||68 km.|
|Sense of movement||Normal|
Comments: Bedrock fault exposure with slickenlines that rake 60? east, located <250 m west of Arches National Park visitors center (Doelling and others, 2002 #6764).
The Moab fault is subdivided into northern, central, and southern parts based on fault geometry, varying amounts of displacement along strike, geomorphic trends (including reversed scarp topography along the northern part), and concealment of the fault beneath Quaternary basin fill along the southern part (Olig and others, 1996 #1371). Valley-margin deformation collocated with the southern part of the fault includes complex, anastomosing faults, fractures, and folds, indicating salt dissolution-related subsidence (Doelling and others, 2002 #6764). The non-tectonic deformation is likely an ongoing process (Doelling and others, 2002 #6764; Hylland and Mulvey, 2003 #6766), evidenced by marsh development at the northwestern end of Moab-Spanish Valley, basin-ward convergence of Bull Lake-aged (~130-200 ka) alluvial terraces near the middle of the valley, and the entrenchment of older alluvial-fan surfaces and successively younger basin-ward directed fan deposition. However, hydrologic controls on deposition could also explain these observed relations. Salt dissolution-related deformation may include unusual Bull Lake terrace geometries, several small (10-cm) displacements in the middle to late Pleistocene deposits, and the beheading of Little Canyon, formed during late Tertiary to early Quaternary time (Oviatt, 1988 #5006).
|Age of faulted surficial deposits||Cretaceous.|
|Most recent prehistoric deformation||
undifferentiated Quaternary (<1.6 Ma)
Comments: Several lines of evidence indicate that the Moab fault has not been active during the Quaternary, although the age constraints are not conclusive. Olig and others (1996 #1371) infer pre-Quaternary displacement on the fault that is spatially similar but kinematically unrelated to Quaternary collapse of the Moab-Spanish Valley salt-cored anticline. Their inference is based on: cross-cutting relationships indicating salt dissolution more recent than fault movement (Doelling, 1988 #6762; Doelling and others, 2002 #6764), fault deformation structures (e.g., cemented vein arrays and cataclastic shear zones), multiple episodes of salt diapirism; however, no differential offset of Permian to Lower Jurassic geologic units, a lack of correlation between the locations of maximum fault displacement and maximum salt thickness, and an estimate of 1.2-7.5 Ma required to erode the bedrock fault escarpment back to its present condition, based on bedrock scarp-retreat rates (0.2-0.5 m/k.y., Olig and others, 1996 #1371).
Displacement on the Moab fault may have occurred between the Upper Cretaceous (Campanian to Turonian) and Quaternary (Foxford and others, 1996 #6765; Olig and others, 1996 #1371; Woodward-Clyde Federal Services, 1996 #5027); however, the oldest deposits not cut by the Moab fault are middle to late Pleistocene in age. Conversely, movement along deformation bands related to collapse of the Moab-Spanish Valley salt-cored anticline postdates early and middle Pleistocene alluvium (Harden and others, 1985 #4988).
Less than 0.2 mm/yr
Comments: Olig and others (1996 #1371) estimated the long-term geologic slip rate along the Moab fault for the period between 2 and 24 Ma as 0.008 mm/yr (0.18 km/22 m.y.) for the northern part, 0.036 mm/yr (0.79 km/22 m.y.) for the central part, and 0.014 mm/yr (0.31 km/22 m.y.) for the southern part.
|Date and Compiler(s)||
Bill D. Black, Utah Geological Survey
Michael D. Hylland, Utah Geological Survey
Suzanne Hecker, U.S. Geological Survey
#5828 Black, B.D., Hecker, S., Hylland, M.D., Christenson, G.E., and McDonald, G.N., 2003, Quaternary fault and fold database and map of Utah: Utah Geological Survey Map 193DM, CD-ROM, ISBN 1-55791-593-8, 1pl., scale 1:500,000.
#6764 Doelling, H.H., Ross, M.L., and Mulvey, W.E., 2002, Geologic map of the Moab 7.5' quadrangle, Grand County, Utah: Utah Geological Survey Map 181, 34 p. pamphlet, 2 sheets, scale 1:24,000.
#6765 Foxford, K.A., Garden, I.R., Guscott, S.C., Burley, S.D., Lewis, J.J.M., Walsh, J.J., and Watterson, J., 1996, The field geology of the Moab fault, in Huffman, A.C., Jr., Lund, W.R., and Godwin, L.H., eds., Geology and resources of the Paradox Basin: Utah Geological Association Guidebook 25, p. 265-283.
#4988 Harden, D.R., Biggar, N.E., and Gillam, M.L., 1985, Quaternary deposits and soils in and around Spanish Valley, Utah, in Weide, D.L., and Faber, M.L., eds., Soils and Quaternary geology of the southwestern United States: Geological Society of America Special Paper 203, p. 43-64.
#642 Hecker, S., 1993, Quaternary tectonics of Utah with emphasis on earthquake-hazard characterization: Utah Geological Survey Bulletin 127, 157 p., 6 pls., scale 1:500,000.
#6766 Hylland, M.D., and Mulvey, W.E., 2003, Geologic hazards of Moab-Spanish Valley, Grand County, Utah: Utah Geological Survey Special Study 107, 25 p., 4 pls. on compact disc, scale 1:24,000.
#4993 Jones, R.W., 1959, Origin of salt anticlines of Paradox Basin—Colorado, Utah: American Association of Petroleum Geologists Bulletin, v. 43, no. 8, p. 1869-1895.
#6767 McKnight, E.T., 1940, Geology of the area between Green and Colorado Rivers, Grand and San Juan Counties, Utah: U.S. Geological Survey Bulletin 908, 147 p., 1 pl., scale 1:62,500.
#1371 Olig, S.S., Fenton, C.H., McCleary, J., and Wong, I.G., 1996, The earthquake potential of the Moab fault and its relation to salt tectonics in the Paradox Basin, Utah, in Huffman, A.C., Jr., Lund, W.R., and Godwin, L.H., eds., Geology and resources of the Paradox Basin: Utah Geological Association Guidebook 25, p. 251-264.
#5006 Oviatt, C.G., 1988, Evidence for Quaternary deformation in the Salt Valley anticline, southeastern Utah, in H., D.H., Oviatt, C.G., and Huntoon, P.W., eds., Salt deformation in the Paradox region: Utah Geological and Mineral Survey Bulletin 122, p. 61-76.
#6772 Schell, B.A., 1994, Blue Cut fault, Riverside County, southern California: South Coast Geological Society, Annual field trip guidebook 22, p. 208-221.
#5009 Shoemaker, E.M., Case, J.E., and Elston, D.P., 1958, Salt anticlines of the Paradox Basin, in Sanborn, A.R., ed., Guidebook to the geology of the Paradox Basin: Intermountain Association of Petroleum Geologists, Ninth Annual Field Conference, p. 39-59.
#2789 Williams, P.L., 1964, Geology, structure, and uranium deposits of the Moab quadrangle, Colorado and Utah: U.S. Geological Survey Miscellaneous Geologic Investigations I-360.
#5025 Woodward-Clyde Consultants, 1982, Geologic characterization report for the Paradox Basin study region, Utah study areas, volume II, Gibson Dome: Technical report to Battelle Memorial Institute, Office of Nuclear Waste Isolation, under Contract ONWI-290, variously paginated, scale 1:340,000.
#5026 Woodward-Clyde Consultants, 1984, Geologic characterization report for the Paradox Basin study region, Utah study areas, volume VI, Salt Valley: Technical report to Battelle Memorial Institute, Office of Nuclear Waste Isolation, under Contract ONWI-290, 190 p.
#6768 Woodward-Clyde Consultants, 1986, Paradox Basin draft project summary report, Chapter 1—Geology: Oakland, California, consultant's report, 5 vols., variously paginated.
#5027 Woodward-Clyde Federal Services, 1996, Evaluation and potential seismic and salt dissolution hazards at the Atlas Uranium Mill tailings site, Moab, Utah: Technical report to Smith Environmental Technologies and Atlas Corporation, under Contract SK9407, variously paginated.