 |
 |
Not as large but beautifully exposed in 3D in a succession of deep glaciated canyons is the Lamoille Canyon nappe in the Ruby Mountains, Nevada. The nappe has a maximum overturned limb width 9 km perpendicular to strike (length >22 km). Structurally above it (with opposite vergence) is an example of a small nappe derived by rotation of an initially upright fold: the Soldier Creek nappe, the upright root of which is sheared out upward into the sheath-shaped nappe where caught up in extensional shear zone (overturned limb 4 km wide perpendicular to transport). The inverted limb of the basement-cored, thrust-floored Scanlon nappe in the Mojave Desert of California tracks >45 km along strike. Keith Howard, K.A., 1980, Metamorphic infrastructure in the northern Ruby Mountains, Nevada, in Crittenden, M.D., Jr., Coney, P.J., and Davis, G.H. eds., Cordilleran metamorphic core complexes: Geological Society of America Memoir 153, p. 335-347. Howard, K.A., 1987, Lamoille Canyon nappe in the Ruby Mountains metamorphic core complex, Nevada, in Hill, M.L., ed., Cordilleran section of the Geological Society of America: Geological Society of America Centennial Field Guide v. 1, p. 95-100. MacCready, Tyler, Snoke, A.W., Wright, J.E., and Howard, K.A., 1997, Mid-crustal flow during Tertiary extension in the Ruby Mountains core complex, Nevada: Geological Society of America Bulletin, v. 109, p. 1576-1594. Howard K.A., John, B.E., and Miller, C.F., 1987, Metamorphic core complexes, Mesozoic ductile thrusts, and Cenozoic detachments: Old Woman Mountains - Chemehuevi Mountains transect, California and Arizona, in Davis, G.H. and Vandendolder, E.M., eds., Geologic diversity of Arizona and its margins: Excursions to choice areas: Arizona Bureau of Geology and Mineral Technology Special paper 5, p. 365-382. Howard, K.A., 2002, Geologic map of the Sheep Hole Mountains 30' x 60' quadrangle, San Bernardino and Riverside Counties, California: U.S. Geological Survey map MF-2344, 2 sheets, http://pubs.usgs.gov/mf/2002/2344/, (1:100,000). -- Keith A. Howard Scientist Emeritus U.S. Geological Survey, MS 973 Menlo Park, CA 94025 U.S.A. phone 1-650-329-4943 fax 1-650-329-5133