Research Article| February 01, 1984 Role of tectonic denudation in warping and uplift low-angle normal faults Jon E. Spencer 1Arizona Bureau Geology Mineral Technology, 845 N. Park Avenue, Tucson, Arizona 85719 Search for other works by this author on: GSW Google Scholar Author Article Information Publisher: Geological Society America First Online: 01 Jun 2017 Online ISSN: 1943-2682 Print 0091-7613 (1984) 12 (2): 95–98. https://doi.org/10.1130/0091-7613(1984)12<95:ROTDIW>2.0.CO;2 history...

The Colorado Plateau is blanketed by Phanerozoic marine and nonmarine strata as young Cretaceous that are now exposed at elevations of about 2 km. Crustal thickening due to magmatism horizontal crustal shortening was far less than necessary cause this uplift, which commonly attributed the consequences mantle lithosphere thinning heating. midcontinent region around Iowa consist Precambrian bedrock overlain a similar amount Paleozoic platformal strata, thus both regions once had lithospheric...

Research Article| November 01, 1979 Tosco-Abreojos fault zone: A Neogene transform plate boundary within the Pacific margin of southern Baja California, Mexico Jon E. Spencer; Spencer 1U.S. Geological Survey, 345 Middlefield Road, Menlo Park, California 94025 Search for other works by this author on: GSW Google Scholar William R. Normark Author and Article Information Publisher: Society America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print 0091-7613 Geology (1979) 7 (11): 554–557....

Large‐magnitude Miocene extension in west central Arizona occurred primarily along three imbricate, northeast dipping normal faults. The structurally highest of these faults, the gently Buckskin‐Rawhide detachment fault, accommodated approximately 66 km crustal extension, whereas two lower faults a total about 20 extension. Due to this large‐magnitude an area at Earth's surface that was 10 wide is now over 100 wide, and crystalline rocks with mid‐Tertiary mylonitic fabrics, uncovered by...

Research Article| June 01, 1997 Sr isotope evidence for a lacustrine origin the upper Miocene to Pliocene Bouse Formation, lower Colorado River trough, and implications timing of Plateau uplift Jon E. Spencer; Spencer 1Arizona Geological Survey, 416 West Congress Street, Suite 100, Tucson, Arizona 85701 Search other works by this author on: GSW Google Scholar P. Jonathan Patchett 2Department Geosciences, University Arizona, 85721 Author Article Information Publisher: Society America First...

Research Article| October 01, 1982 Magnitude of crustal extension in the southern Great Basin Brian Wernicke; Wernicke 1Department Earth and Planetary Sciences, Massachusetts Institute Technology, Cambridge, 02139 Search for other works by this author on: GSW Google Scholar Jon E. Spencer; Spencer B. Clark Burchfiel; Burchfiel Peter L. Guth Author Article Information Publisher: Geological Society America First Online: 01 Jun 2017 Online ISSN: 1943-2682 Print 0091-7613 Geology (1982) 10 (10):...

Research Article| May 01, 1985 Evidence for large-scale transport on the Bullard detachment fault, west-central Arizona Stephen J. Reynolds; Reynolds 1Arizona Bureau of Geology and Mineral Technology, 845 North Park Avenue, Tucson, 85719 Search other works by this author on: GSW Google Scholar Jon E. Spencer (1985) 13 (5): 353–356. https://doi.org/10.1130/0091-7613(1985)13<353:EFLTOT>2.0.CO;2 Article history first online: 01 Jun 2017 Cite View This Citation Add to Manager Share Icon Facebook...

The lower Pliocene Bouse Formation in the Colorado River Valley (southwestern USA) consists of basal marl and dense tufa overlain by siltstone fine sandstone. It is locally interbedded with sands derived from River. We briefly review 87Sr/86Sr analyses carbonates shells carbonate gypsum similar age east Las Vegas that indicate all these strata are isotopically to modern water. also add new data consistent a step maximum elevations 330 m south Topock Gorge 555 north. New geochemical glass...

HE institution known as the hill station or summer resort is a phenomenon connected with residence of Occidental in Orient.' Going to hills regular part annual calendar nearly all Occidentals whose economic status and employment affiliations will permit somewhat extended vacation at resort. The not native but one developed during nineteenth century by British Dutch colonial masters order make sojourns foreign land less uncomfortable. In past hill-station custom has spread throughout Orient,...

The Maria fold‐and‐thrust belt (MFTB) is a narrow of Mesozoic crustal shortening that trends east‐west across west central Arizona and adjacent southeastern California. It characterized by generally south vergent folds thrusts commonly displace Proterozoic crystalline rocks over deformed metamorphosed Paleozoic strata. MFTB cut to southeast trending mid‐Tertiary extensional deformation. Extension was large displacements on low‐angle normal faults, known as detachment isostatic uplift...

The mechanics of low‐angle normal faulting has proved difficult to establish despite clear geological evidence for the existence such faults. Gently dipping shear stress trajectories are necessary nucleation and propagation faults in a structurally isotropic medium. Such not produced by simple horizontal extension, but do arise presence flexural stresses. We model conditions cross section through strong upper crust using Airy functions two‐dimensional elastic Numerical modeling indicates...

Research Article| March 01, 1986 Possible controls of base- and precious-metal mineralization associated with Tertiary detachment faults in the lower Colorado River trough, Arizona California Jon E. Spencer; Spencer 1Arizona Bureau Geology Mineral Technology, 845 North Park Avenue, Tucson, 85719 Search for other works by this author on: GSW Google Scholar John W. Welty (1986) 14 (3): 195–198. https://doi.org/10.1130/0091-7613(1986)14<195:PCOBAP>2.0.CO;2 Article history first online: 01 Jun...

Homer Mountain and surrounding regions are within, or adjacent to, the western part of a broad region low-angle normal faults exposed within lower Colorado River trough. During middle Miocene time, upper-plate rocks in Homer, Sacramento, Dead, Newberry Mountains moved eastward northeastward, relative to plate, above single multiple faults. Deposition coarse clastic sedimentary occurred during extensional faulting was accompanied by, closely followed eruption basaltic volcanics. Upper-plate...

Research Article| October 01, 2010 The Paleogene California River: Evidence of Mojave-Uinta paleodrainage from U-Pb ages detrital zircons Steven J. Davis; Davis * 1Department Global Ecology, Carnegie Institution Washington, Stanford, 94305, USA *E-mail: sjdavis@carnegie.stanford.edu. Search for other works by this author on: GSW Google Scholar William R. Dickinson; Dickinson 2Department Geosciences, University Arizona, Tucson, Arizona 85721, George E. Gehrels; Gehrels Jon Spencer; Spencer...

The Space-Shuttle Radar Topography Mission provided geologists with a detailed digital elevation model of most Earth’s land surface. This new database is used here for structural analysis grooved surfaces interpreted to be the exhumed footwalls three active or recently extensional detachment faults. Exhumed fault footwalls, each an areal extent one hundred several square kilometers, make up much Dayman dome in eastern Papua New Guinea, western Gurla Mandhata massif central Himalaya, and...

Rice is a staple part of the diet virtually every Malaysian, to extent that in each major languages used Malaysia, rice means food and rice. Drawing on wide range sources, Malaya opens with an examination often fragmentary evidence rice-growing prehistoric South-East Asia then considers great changes followed rise commercial agriculture region before during colonial times. A pioneering work when it first appeared 1977, successfully combined area-by-area approach geographer period-by-period...

In this paper, we use several analytical methods in an effort to better understand the systematics of (U-Th)/He chronometer hematite and manganese oxides. ^4^He diffusion data from a polycrystalline sample is consistent with crystals range sizes similar those directly observed material. Combined compilation He previous studies, supports interpretation that general crystal size primary control on retentivity hematite. ^4^He/^3^He single fragment larger imply presence multiple domains smaller...

Cenozoic magmatism in southwestern Arizona, which is within the Basin and Range tectonic province, occurred almost entirely between 15 25 Ma. Volcanic rocks typically consist, ascending order, of (1) a thin sequence mafic to intermediate lava flows, (2) voluminous felsic flows pyroclastic with minor moderate amounts (3) basalt andesite. rock sequences rest disconformably on pre‐Tertiary bedrock most areas but locally overlie substantial coarse clastic debris that was deposited immediately...

Research Article| September 01, 2010 A late Miocene–early Pliocene chain of lakes fed by the Colorado River: Evidence from Sr, C, and O isotopes Bouse Formation related units between Grand Canyon Gulf California Jennifer A. Roskowski; Roskowski 1Department Geosciences, University Arizona, Tucson, Arizona 85721, USA Search for other works this author on: GSW Google Scholar P. Jonathan Patchett; Patchett † †E-mail: patchett@email.arizona.edu Jon E. Spencer; Spencer 2Arizona Geological Survey,...