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1

A REVIEW OF THE VERTEBRATE FAUNA OF THE LOWER JURASSIC NAVAJO SANDSTONE IN ARIZONA  

Microsoft Academic Search

The Lower Jurassic Navajo Sandstone of northern Arizona and southern Utah has yielded a diverse assemblage of late Early Jurassic terrestrial tetrapods from eolian and associated paleoenvironments. Although rare, vertebrate body fossils are represented by specimens of tritylodonts, crocodylomorphs, sauropodomorphs, and basal theropods (including Segisaurus halli). The vertebrate ichnofossil record is diverse and includes synapsids (Brasilichnium), crocodylomorphs (cf. Batrachopus), ornithischians

RANDALL B. IRMIS

2005-01-01

2

Bleaching of Jurassic Navajo Sandstone on Colorado Plateau Laramide highs: Evidence of exhumed hydrocarbon supergiants?  

NASA Astrophysics Data System (ADS)

Spectacular color variations in the Lower Jurassic Navajo Sandstone reflect stratigraphic and structural control on the spatial distribution of fluid-driven alteration. Field observations and supervised classification of Landsat 7 Enhanced Thematic Mapper (ETM+) satellite imagery show that the most extensive regional bleaching of the Navajo Sandstone occurs on eroded crests of Laramide uplifts on the Colorado Plateau in southern Utah. Alteration patterns suggest that the blind reverse faults that core the eastern monoclines associated with these uplifts were carriers for hydrocarbons and brought the buoyant fluids to the crests of monoclines and anticlines, where they bleached the sandstone in both structural and stratigraphic traps. The extent of bleaching indicates that the Navajo Sandstone (Navajo Sandstone, Aztec Sandstone, and Nugget Sandstone) may have been one of the largest hydrocarbon reservoirs known. Rapid incision and breaching of this reservoir during Tertiary uplift and erosion of the Colorado Plateau could have released enough carbon into the atmosphere to significantly contribute to global carbon fluxes and possibly influence climate.

Beitler, Brenda; Chan, Marjorie A.; Parry, William T.

2003-12-01

3

An example of liquefaction-induced interdune sedimentation from the early Jurassic Navajo Sandstone, USA  

NASA Astrophysics Data System (ADS)

Extensive outcrops of Navajo Sandstone in the southwestern United States expose eolian dune deposits that are subdivided in a complex array of foresets and bounding surfaces. In the Glen Canyon region, and other places, this architecture is frequently disrupted by large-scale, soft-sediment deformation features. These features have been attributed to episodic liquefaction events that affected saturated sand below the level of the interdune surface. Though erosional truncation of deformation features indicates that liquefaction often occurred in the uppermost levels of Navajo dune deposits, very few paleotopographic disruptions due to subsurface deformation have been documented. Navajo Sandstone outcrops in West Canyon, Utah, provide unusually comprehensive exposure of architectural details linking large-scale deformation features and associated interdune deposits, enabling a well constrained appraisal of their genesis. At this location, a 23 m succession of sandstone, mudstone, carbonate, and chert deposits overlies a zone of deformation that extends, laterally, for hundreds of meters. This horizontally stratified lens occupies an abrupt synform along a bounding surface between successive crossbeds that otherwise appears as a featureless, sub-horizontal plane. Large-scale foresets below this bounding surface oversteepen at the margins of the synform and grade downdip into contorted stratification and structureless expanses. The authors propose that liquefaction in the Jurassic erg caused localized subsidence of a minor portion of a dry interdune surface to a position several meters below the contemporary water table. A succession of hyperpycnal sand flows, lacustrine evaporites, and eolian sheet and dune deposits filled this depression prior to the advance of large dunes across the site. The process/response dynamics evident in this outcrop suggest that deformation may have exercised significant, non-systematic control over depositional architectures in areas of the erg prone to liquefaction. Similar dynamics are unknown from modern desert environments and their intrinsic scale defies laboratory simulation; therefore, close investigation of these ancient features is essential for exploring the full range of depositional controls that may be encountered in other ancient eolianites on Earth and in eolian accumulations on other planets.

Bryant, Gerald; Monegato, Giovanni; Miall, Andrew

2013-11-01

4

Porosity and grain size controls on compaction band formation in Jurassic Navajo Sandstone  

USGS Publications Warehouse

Determining the rock properties that permit or impede the growth of compaction bands in sedimentary sequences is a critical problem of importance to studies of strain localization and characterization of subsurface geologic reservoirs. We determine the porosity and average grain size of a sequence of stratigraphic layers of Navajo Sandstone that are then used in a critical state model to infer plastic yield envelopes for the layers. Pure compaction bands are formed in layers having the largest average grain sizes (0.42–0.45 mm) and porosities (28%), and correspondingly the smallest values of critical pressure (-22 MPa) in the sequence. The results suggest that compaction bands formed in these layers after burial to -1.5 km depth in association with thrust faulting beneath the nearby East Kaibab monocline, and that hardening of the yield caps accompanied compactional deformation of the layers.

Schultz, Richard A.; Okubo, Chris H.; Fossen, Haakon

2010-01-01

5

Sandstone Formation on the Navajo Loop Trail  

USGS Multimedia Gallery

Views along the Navajo Loop Trail in Bryce Canyon National Park. Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolomite that caps them and the sandston...

6

Downslope coarsening in aeolian grainflows of the Navajo Sandstone  

NASA Astrophysics Data System (ADS)

Downslope coarsening in grainflows has been observed on present-day dunes and generated in labs, but few previous studies have examined vertical sorting in ancient aeolian grainflows. We studied the grainflow strata of the Jurassic Navajo Sandstone in the southern Utah portion of its outcrop belt from Zion National Park (west) to Coyote Buttes and The Dive (east). At each study site, thick sets of grainflow-dominated cross-strata that were deposited by large transverse dunes comprise the bulk of the Navajo Sandstone. We studied three stratigraphic columns, one per site, composed almost exclusively of aeolian cross-strata. For each column, samples were obtained from one grainflow stratum in each consecutive set of the column, for a total of 139 samples from thirty-two sets of cross-strata. To investigate grading perpendicular to bedding within individual grainflows, we collected fourteen samples from four superimposed grainflow strata at The Dive. Samples were analyzed with a Malvern Mastersizer 2000 laser diffraction particle analyser. The median grain size of grainflow samples ranges from fine sand (164 ?m) to coarse sand (617 ?m). Using Folk and Ward criteria, samples are well-sorted to moderately-well-sorted. All but one of the twenty-eight sets showed at least slight downslope coarsening, but in general, downslope coarsening was not as well-developed or as consistent as that reported in laboratory subaqueous grainflows. Because coarse sand should be quickly sequestered within preserved cross-strata when bedforms climb, grain-size studies may help to test hypotheses for the stacking of sets of cross-strata.

Loope, David B.; Elder, James F.; Sweeney, Mark R.

2012-07-01

7

Biosignatures in Spheroidal Iron Oxide-Rich Concretions from the Navajo Sandstone  

NASA Astrophysics Data System (ADS)

Spheroidal concretions composed of an iron oxide-rich cemented outer rind and a weakly-cemented core of bleached (iron depleted) sandstone are abundant in the Jurassic Navajo Sandstone of the Colorado Plateau. The formation of the spheroidal concretions has been previously described as a result of advective mixing between Fe(II)-rich reducing fluids with oxidizing fluids resulting in the subsequent abiotic precipitation of Fe(III) oxides forming the spheroidal concretions. The role of microbial biomineralization has been suggested as a potential mechanism of various other iron oxide formations, such as banded iron formations and iron-manganese nodules. Here we describe a series of qualitative and quantitative observations within the spheroidal concretions from the Jurassic Navajo Sandstone consistent with prior microbial activity. Spheroidal concretions were collected from Spencer Flat, east of Escalante, in south-central Utah, sectioned, and treated with dilute hydrochloric acid and acetone to remove traces of inorganic and organic carbon (C) from the surface of the samples. Elemental analysis of the treated specimens revealed elevated C as well as nitrogen (N) content with respect to the interior of the concretion (Rind, C, 0.06%, N, 0.006%; Interior, C, 0.009%, N, 0.003%). Elevated C and N values in the rind suggest carbon-nitrogen rich compounds consistent with biomolecules. Field Emission Scanning Electron Microscopy (FE-SEM) confirmed the presence of C as well as N and S via electron backscattering analysis. Additionally, structures morphologically consistent with bacterial cells have been observed via FE-SEM in association with a matrix that coated sand grains within the iron oxide-rich rind. Together these data suggest that microorganisms were associated with the iron oxide-rich spheroidal concretions. Microbial iron oxidation has been demonstrated to be ubiquitous microbial metabolism and is facilitated by a diversity of microorganisms in terrestrial surface and subsurface environments. Thus, Fe(II) and oxidizing fluids could have supported an iron oxidizing microbial community. Microbial catalysis and iron biomineralization may thus offer an alternative hypothesis regarding the formation and geochemical characteristics of the spheroidal iron oxide-rich concretions in the Jurassic Navajo Sandstone of the Colorado Plateau.

Spanbauer, T. L.; Kettler, R. M.; Loope, D. B.; Weber, K. A.

2009-12-01

8

Blueberries on Earth and Mars: Correlations Between Concretions in Navajo Sandstone and Terra Meridiani on Mars.  

NASA Astrophysics Data System (ADS)

Concretionary Fe-Mn-rich nodular authigenic constituents of Jurassic Navajo sandstone (moki marbles) bear a certain relationship to similar concretionary forms ('blueberries') observed on Mars. Their origin on Earth is considered to invoke variable redox conditions with underground fluids penetrating porous quartz-rich sandstone leading to precipitation of hematite and goethite-rich material from solution, generally forming around a central nucleus of fine particles of quartz and orthoclase, recently verified by XRD and SEM-EDS analyses. At the outer rim/inner nucleus boundary, bulbous lobes of fine-grained quartz often invade and fracture the outer rim armored matrix. The bulbous forms are interpreted to result from fluid explusion from the inner concretionary mass, a response to pressure changes accompanying overburden loading. Moki marbles, harder than enclosing rock, often weather out of in situ sandstone outcrops that form a surface lag deposit of varnished marbles that locally resemble desert pavement. The marbles appear morphologically similar to 'blueberries' identified on the martian surface in Terra Meridiani through the MER-1 Opportunity rover. On Earth, redox fluids responsible for the genesis of marbles may have emanated from deep in the crust (often influenced by magmatic processes). These fluids, cooling to ambient temperatures, may have played a role in the genesis of the cemented outer rim of the concretions. The low frequency of fungi filaments in the marbles, contrasts with a high occurrence in Fe-encrusted sands of the Navajo formation [1], indicating that microbial content is of secondary importance in marble genesis relative to the fluctuating influx of ambient groundwater. Nevertheless, the presence of filaments in terrestrial concretions hints at the possibility of discovering fossil/extant life on Mars, and thus should be considered as prime targets for future reconnaissance missions to Mars. 1] Mahaney, W.C., et al. (2004), Icarus, 171, 39-53.

Mahaney, W. C.; Milner, M. W.; Netoff, D.; Dohm, J.; Kalm, V.; Krinsley, D.; Sodhi, R. N.; Anderson, R. C.; Boccia, S.; Malloch, D.; Kapran, B.; Havics, A.

2008-12-01

9

CO2-Driven Convection Produced the Vertical Distribution of Sandstone Colors and Iron Concretions in Navajo Sandstone at Zion National Park, Utah (USA)  

NASA Astrophysics Data System (ADS)

Along cliff faces exposed in Zion National Park (SW Utah), the porous and permeable Navajo Sandstone (Jurassic) is 700 m thick, and is capped by impermeable mudrocks and evaporites of the Carmel Formation. Previous workers have documented an areally extensive color pattern that is easily visible across much of southwestern and south-central Utah: the uppermost Navajo Sandstone is nearly white, the middle third of the formation is pink, and the lowermost fraction is reddish brown. To the northwest of the park, however, the formation is uniformly red (likely its primary color; G.B. Nielsen et al., 2009). Spheroidal concretions with dense, iron-oxide-cemented rinds and iron-poor cores are abundant in the pink and brown sandstones. Rhomb-shaped clots of iron oxide cement that are pseudomorphous after siderite are present in the cores of the largest concretions. The color variations are evidence that iron was transported from the upper portion of the Navajo SS to the lower portion. The pseudomorphs are evidence that the concretions are the oxidized remains of siderite-cemented precursors. The vertical iron transport and the precipitation of siderite require similar vertical transport of reducing, CO2-rich formation waters through the Navajo Sandstone. We argue that this circulation was driven in part by groundwater convection beneath a CO2 accumulation that was trapped below the Navajo-Carmel contact. This circulation caused aqueous iron and aqueous carbonate to be displaced downward and to accumulate (in the form of siderite) in the lower Navajo Sandstone. There are numerous CO2 reservoirs in the Colorado Plateau region; the gas was derived mainly from mantle sources. We hypothesize that, in the late Tertiary, the Carmel Formation capped a broad, structurally high accumulation of CO2 and CH4 in the Navajo Sandstone. The CH4 bleached the upper portion of the sandstone, releasing Fe2+ into the formation water. CO2 dissolved in the water, thereby increasing its density, and causing it to sink. The alkalinity of this down-welling water gradually increased as aqueous CO2 was either consumed via alteration of detrital feldspar grains or lost via degassing. Siderite then started to precipitate, and continued to precipitate as long as a source of iron was present in the down-welling water. Finally, the siderite was oxidized when uplift of the Colorado Plateau led to loss of the gas cap and ingress of oxidizing groundwater. Increased interest in the fate of CO2 injected into porous rocks has prompted detailed modeling of the convective overturn of the formation waters that underlie CO2 accumulations. The distribution and paragenesis of iron oxides in the Navajo Sandstone of southwestern Utah provide a well-exposed end product of this important geologic process.

Kettler, R. M.; Loope, D. B.

2011-12-01

10

Synapsid Burrows in the Lower Jurassic Navajo Sandstone, Utah  

E-print Network

and Bolles, 1975), lungfish (Romer and Olson, 1954; Carlson, 1968; Olson and Bolles, 1975; Dalquest and Carpenter, 1977; Hasiotis et al., 1993), therapsids (Smith, 1987; Groenewald et al., 2001; Damiani et al., 2003), bear dogs (Hunt et al., 1983), beavers... and Kraus, 1983; Gobetz, 2006; Gobetz and Martin, 2006), beavers (Barbour 1892, 1897), enigmatic mammals (Hasiotis, 2002; Hasiotis et al., 2004; Hembree and Hasiotis, 2008), and an enigmatic excavator (Loope, 2006a). Identification of the excavator...

Riese, David

2011-05-03

11

Eolian sabkha sandstones in the Nugget Sandstone (Jurassic), Vernal area, Utah  

SciTech Connect

The Jurassic Nugget Sandstone in the Vernal, Utah, area is characterized by thick (up to 25 m) sets of cross-stratified eolian dune sandstone separated by either erosional planar bounding surfaces or thin (mostly < 3 m) sandstones interpreted as sabkha sandstones. Structures in Nugget sabkha sandstones are predominantly wavy or irregular bedding and thin, remnant sets of dune cross-strata consisting of eolian ripple and avalanche strata. The types of sedimentary structures and erosional features in Nugget sabkha sandstones indicate a close relationship between sand deposition and erosion and fluctuations in the local water table. Thin, remnant eolian dune sets are common in Nugget sabkha sandstones. The remnant sets form when dunes migrating across a sabkha are partially wetted as the water table rises slightly (on a scale of tens of centimeters); the lower part of the dune with wetted sand remains on the sabkha as the rest of the dune continues to migrate. Typically, ripple strata of the dune apron and the toes of avalanche strata are preserved in dune remnants. The avalanche strata, being slightly coarser grained, are preferentially deflated, leaving microtopography. This topography is commonly filled in with ripple strata that form as dry sand again blows across the sabkha. Stacked sets of remnant dunes separated by erosional surfaces illustrate the control of sand deposition on eolian sabkhas by the local water table.

Schenk, C.J.; Peterson, F. (Geological Survey, Denver, CO (United States))

1991-06-01

12

Properties of Cotton Valley sandstone reservoirs (Upper Jurassic), Terryville Field, Lincoln Parish, Louisiana  

E-print Network

PROPERTIES OF COTTON VALLEY SANDSTONE RESERVOIRS (UPPER JURASSIC), TERRYVILLE FIELD, LINCOLN PARISH, LOUISIANA A Thesis by KAREN 'CELE MCBRIDE Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirement... for the degree of MASTER OF SCIENCE August 1982 Major Subject: Geology PROPERTIES OF COTTON VALLEY SANDSTONE RESERVOIRS (UPPER JURASSIC), TERRYVILLE FIELD, LINCOLN PARISH, LOUISIANA A Thesis by KAREN 'CELE MCBRIDE Approved as to style and content by...

McBride, Karen 'Cele

1982-01-01

13

Diagenesis of Cotton Valley sandstone (Upper Jurassic), East Texas: Implications for tight gas formation pay recognition  

Microsoft Academic Search

The Upper Jurassic Cotton Valley sandstone comprises a thick siliciclastic sequence in the East Texas basin. These sediments were deposited in a dominantly progradational sequence of shallow marine and fluvial-deltaic environments. Along the eastern flank of the basin, natural gas is produced from low porosity and low-permeability reservoirs which have been stimulated by massive hydraulic fracturing. Cotton Valley sandstones generally

Wescott

1983-01-01

14

Diagenesis of a tight gas formation: Jurassic Cotton Valley Sandstone, East Texas basin  

Microsoft Academic Search

The Upper Jurassic Cotton Valley Sandstone is a thick siliciclastic unit in the East Texas basin. Along the eastern flank of the basin, natural gas is produced from Cotton Valley reservoirs characterized by low porosity and permeability, which have been stimulated by massive hydraulic fracturing. Cotton Valley sandstones are generally very fine-grained, well-sorted quartz arenites and subarkoses. Principal framework constituents

William A. Wescott

1984-01-01

15

Net-Infiltration Map of the Navajo Sandstone Outcrop Area in Western Washington County, Utah  

USGS Publications Warehouse

As populations grow in the arid southwestern United States and desert bedrock aquifers are increasingly targeted for future development, understanding and quantifying the spatial variability of net infiltration and recharge becomes critically important for inventorying ground-water resources and mapping contamination vulnerability. A Geographic Information System (GIS)-based model utilizing readily available soils, topographic, precipitation, and outcrop data has been developed for predicting net infiltration to exposed and soil-covered areas of the Navajo Sandstone outcrop of southwestern Utah. The Navajo Sandstone is an important regional bedrock aquifer. The GIS model determines the net-infiltration percentage of precipitation by using an empirical equation. This relation is derived from least squares linear regression between three surficial parameters (soil coarseness, topographic slope, and downgradient distance from outcrop) and the percentage of estimated net infiltration based on environmental tracer data from excavations and boreholes at Sand Hollow Reservoir in the southeastern part of the study area. Processed GIS raster layers are applied as parameters in the empirical equation for determining net infiltration for soil-covered areas as a percentage of precipitation. This net-infiltration percentage is multiplied by average annual Parameter-elevation Regressions on Independent Slopes Model (PRISM) precipitation data to obtain an infiltration rate for each model cell. Additionally, net infiltration on exposed outcrop areas is set to 10 percent of precipitation on the basis of borehole net-infiltration estimates. Soils and outcrop net-infiltration rates are merged to form a final map. Areas of low, medium, and high potential for ground-water recharge have been identified, and estimates of net infiltration range from 0.1 to 66 millimeters per year (mm/yr). Estimated net-infiltration rates of less than 10 mm/yr are considered low, rates of 10 to 50 mm/yr are considered medium, and rates of more than 50 mm/yr are considered high. A comparison of estimated net-infiltration rates (determined from tritium data) to predicted rates (determined from GIS methods) at 12 sites in Sand Hollow and at Anderson Junction indicates an average difference of about 50 percent. Two of the predicted values were lower, five were higher, and five were within the estimated range. While such uncertainty is relatively small compared with the three order-of-magnitude range in predicted net-infiltration rates, the net-infiltration map is best suited for evaluating relative spatial distribution rather than for precise quantification of recharge to the Navajo aquifer at specific locations. An important potential use for this map is land-use zoning for protecting high net-infiltration parts of the aquifer from potential surface contamination.

Heilweil, Victor M.; McKinney, Tim S.

2007-01-01

16

Groundwater-silicates Reaction Kinetics in the Navajo Sandstone Aquifer, Black Mesa, Arizona (Invited)  

NASA Astrophysics Data System (ADS)

Despite numerous studies of soil profiles and watersheds for critical zone processes, the studies of reaction kinetics in groundwater systems are relatively a few. Yet, aquifers are major sites for water-rock interaction, and a significant segment of the hydrological cycle and global elemental cycling. In this presentation, I will show a multi-discipline study of the Navajo sandstone aquifer at Black Mesa, Arizona. The aeolian sandstone represents some simplest lithology, and the study area has unusually abundant hydrologic, geochemical, isotopic, and paleoclimate data. Solute fluxes along flow paths are supplemented by travel time bounded by 14C and excess 4-He data, from which orders of magnitude estimates of the in situ silicate dissolution rates were calculated. These rates show two to five orders of magnitude slower than those from laboratory experiments at comparable temperature and pH and at far from equilibrium conditions, and are much slower than those derived from studies of soils and watersheds. Data from some new analytical and microscopic methods show that the reaction kinetics are complex. Stable Si isotopes of dissolved Si in groundwater along a 100 km flow path show 2 per mil variation and as low as -1.42‰, representing the most negative dissolved Si isotope composition so far found for natural waters. Near atomic scale transmission electron microscopy show a thin (~ 10 nm) amorphous layer is present on naturally weathered K-feldspars in the aquifer, which requires re-consideration of the details of surface reaction controlled mechanism. However, the new hypothesis of strongly coupled dissolution and precipitation reactions that we have been advancing in recent years appear to be able to explain part of the well-known apparent field-lab discrepancy. The slow precipitation of secondary minerals raised the groundwater saturation state with respect to feldspars to close to equilibrium, and thus retard the feldspar dissolution rates. Our recent laboratory experiments that complement the field study supports the hypothesis. Zhu, C. (2005) In situ feldspar dissolution rates in an aquifer. Geochimica et Cosmochimica Acta v. 69, no.6, 1435-1453, 2005. Zhu, C. Veblen, D.R., Blum, A.E, Chipera, S. (2006) Naturally weathered feldspar surfaces in the Navajo Sandstone aquifer, Black Mesa, Arizona: Electron microscopic characterization. Geochimica et Cosmochimica Acta v. 70, no.18, 4600-4616, 2006 doi:10.1016/j.gca.2006.07.013. Georg, R. B., Zhu, C. Reynolds, R.C., and Halliday, A.N. (2009) Stable silicon isotopes of groundwater, feldspars, and clay coatings in the Navajo Sandstone aquifer, Black Mesa, Arizona, USA. Geochimica et Cosmochimica Acta, v.73, 229-2241. Fu, Q., P ‡Lu, H. ‡Konishi, R. Dilmore, H. Xu, W. E. Seyfried, Jr., and C. Zhu (2009) Coupled alkali-feldspar Dissolution and Secondary Mineral Precipitation in Batch Systems: 1. New Experimental Data at 200°C and 300 bars. Chemical Geology, 91(3), 955-964. Zhu, C., and ‡Lu, P. (2009) Alkali Feldspar Dissolution and Secondary Mineral Precipitation in Batch Systems: 3. Saturation States of Product Minerals and Reaction Paths. Geochimica et Cosmochimica Acta. v.73, p.3171-3120. doi: 10.1016/j.gca.2009.03.015.

Zhu, C.

2009-12-01

17

Damage zone and slip-surface evolution over ?m to km scales in high-porosity Navajo sandstone, Utah  

Microsoft Academic Search

Detailed mapping of throw variations and deformation along twokm-scale normal faults in the high-porosity Navajo sandstone, Utah, has been used to investigate fault growth in this lithology. The faults consist of one or more through-going, striated, slip-surfaces, accommodating the greater part of the offset surrounded by a damage zone consisting of deformation band clusters and short, unconnected slip-surfaces. In contrast

Z. K. Shipton; P. A. Cowie

2001-01-01

18

Investigation of exfoliation joints in Navajo sandstone at the Zion National Park and in granite at the Yosemite National Park by tectonofractographic techniques  

Microsoft Academic Search

Tectonofractographic techniques have been applied to the study of joint exfoliation in the Navajo sandstone at Zion National Park and in the granite at Yosemite National Park. New types of fracture surface morphologies have been observed which enabled the discerning of incipient joints and consequent fracture growth in these rocks. Incipient jointing in the sandstone is mostly manifested by elliptical

D. Bahat; K. Grossenbacher; K. Karasaki

1995-01-01

19

Acoustic Emission and Ultrasonic Characterization of Jurassic Navajo Formation Deformation During Axisymmetric Compression Testing  

NASA Astrophysics Data System (ADS)

Linking continuum-scale and microscale brittle damage in rock remains a challenge impacting CO2 sequestration, secondary recovery, structural monitoring, and other geotechnical engineering applications. We examine if the mode of micromechanical failure scales directly up to continuum-scale damage-induced velocity anisotropy. Axisymmetric drained lab-dry compression experiments are performed on facies of moderately cemented finely laminated quartz arenite from the Jurassic Navajo Formation, a target reservoir rock for CO2 sequestration in Utah. The tests are 1 unconfined uniaxial compression test, 1 hydrostatic compression test, and 3 triaxial compression tests. Microscale damage is monitored using acoustic emissions (AE) and continuum scale damage is monitored with ultrasonic velocity scans. During the non-hydrostatic tests, three to five unload loops are performed pre-failure, with one unload loop performed post-failure. While stresses are increasing, AEs are monitored continuously using 1.6-mm diameter, 0.5-mm thick PZT-5A pins attached circumferentially around the cylindrical sample, and with 6-mm diameter, 2-mm thick PZT-5A discs at the ends of the sample. Before and after each unload loop, the test is paused and the AE transducers sequentially emit an ultrasonic pulse to measure wave speeds. The resulting elastic wave is detected by the other AE transducers. Post-test, the changing anisotropic velocity structure of the rock during compression and failure is compared to the locations, frequency, and relative moment tensors of the AEs measured between ultrasonic scans. Pre- and post-test visual and x-ray CT scan observations of the sample are compared to the acoustic metrics. These tiered observations of rock damage will further elucidate the scaling of microscale brittle failure to the continuum-scale This work was supported as part of the Center for Frontiers of Subsurface Energy Security, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award Number DE-SC0001114. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Rinehart, A. J.; Dewers, T. A.; Holcomb, D. J.; Broome, S. T.

2011-12-01

20

Depositional environments and hydrocarbon occurrence of upper Jurassic Cotton Valley sandstones, Mississippi, Louisiana, and Texas  

Microsoft Academic Search

The sandstones of the Kimmeridgian (Jurassic) upper Cotton Valley Formation of Mississippi, northern Louisiana, and eastern Texas were deposited on a stable subsiding shelf. These sands are regressive and are part of a complex of deltaic and marine systems. They are quartz-rich and exhibit a variety of sedimentary structures. Cotton Valley fluvial-deltaic systems drained Paleozoic and younger highlands to the

Itzchak E. Kornfeld

1985-01-01

21

NEW INFORMATION ON SEGISAURUS HALLI, A SMALL THEROPOD DINOSAUR FROM THE EARLY JURASSIC OF ARIZONA  

E-print Network

NEW INFORMATION ON SEGISAURUS HALLI, A SMALL THEROPOD DINOSAUR FROM THE EARLY JURASSIC OF ARIZONA, a small Early Jurassic dinosaur and the only theropod known from the Navajo Sandstone. Our study unknown in dinosaurs), seemingly solid centra and limb bones (atypical for theropods), and accessory

Hutchinson, John

22

Lower Jurassic Navaho-Aztec-Equivalent Sandstones in southern Arizona and their paleogeographic significance  

SciTech Connect

Thick sequences of Lower Jurassic rhyolitic and andesitic volcanic rocks in several mountain ranges of southern Arizona contain interbedded quartzarenites. Locally up to 250 m thick, these sandstone lenses, composed of well-sorted and well-rounded quartz grains, commonly contain large-scale cross-stratification and are considered to be eolian sand deposits. The eolian sands were blown up against the continental side of the Early Jurassic volcanic arc that trended northwest-southeast across the southwestern margin of the North American continent and/or plate at that time. Paleocurrent data suggest southerly eolian transport of the sands from the Colorado Plateau area. Correlation of these sandstones with the Lower Jurassic Navaho and Aztec Sandstones is indicated by the paleocurrent data as well as radiometric dating of the interbedded volcanics. Eolian sand transport southward across central Arizona in the Early Jurassic indicates that the Mogollon highlands either did not then exist, or were merely low, discontinuous inselbergs on a broad back-arc ramp, more appropriately called the Mogollon slope.

Bilodeau, W.L.; Keith, S.B.

1986-06-01

23

Diagenesis of Cotton Valley sandstone (Upper Jurassic), East Texas: Implications for tight gas formation pay recognition  

SciTech Connect

The Upper Jurassic Cotton Valley sandstone comprises a thick siliciclastic sequence in the East Texas basin. These sediments were deposited in a dominantly progradational sequence of shallow marine and fluvial-deltaic environments. Along the eastern flank of the basin, natural gas is produced from low porosity and low-permeability reservoirs which have been stimulated by massive hydraulic fracturing. Cotton Valley sandstones generally are very finegrained, well-sorted quartz arenites and subarkoses. Principal framework constituents are monocrystalline quartz and feldspars. The sandstones have a complex diagenetic history and are cemented by authigenic quartz, calcite, phyllosilicates, and iron oxides. The most common paragenetic sequence of pore-fill minerals is development of clay coats on grains; formation of syntaxial overgrowths; dissolution of unstable grains followed by precipitation of phyllosilicates; precipitation of calcite in relict primary and secondary pores; and replacement of grains by calcite resulting in a poikilotopic texture. Cotton Valley sandstones are classified by R-mode factor.

Wescott, W.A.

1983-06-01

24

Frisco City sandstone: Upper Jurassic play in southern Alabama  

SciTech Connect

The Frisco City sandstone play in southern Alabama is an example of hydrocarbon entrapment on the flanks of basement erosional features, with principal reservoirs occurring in proximal alluvial-fan to marine shoreface facies. Productive fields are developed on four-way closures of complex geometry, with reservoir sandstones showing maximum thickness along the margins of basement highs that are roughly 1.3-5.18 km{sup 2} in size and have 136-151 m of relief. Detailed analysis of sandstone facies indicates a downdip progression from alluvial-fan through wadi, eolian, beach, tidal-flat, and shoreface deposits. A sequence stratigraphic model based on identification of backstepping strata representing successive transgressive events is useful in predicting maximum reservoir occurrence in the vicinity of inselbergs. Reservoir quality in productive sandstones is high, with porosities ranging from 13 to 27% and permeabilities of 50 md to 5 d. Hydrocarbon occurrence is related to the distribution of high-quality source rock in the Smackover Formation and to maturation history.

Montgomery, S.L. [Petroleum Consultant, Seattle, WA (United States); Baria, L.R. [Jura-Search, Inc., Jackson, MS (United States); Handford, C.R. [Bureau of Economic Geology, Austin, TX (United States)

1997-10-01

25

Oxfordian-Kimmeridgian (Late Jurassic) reservoir sandstones in the Witch Ground Graben, U. K. North Sea  

SciTech Connect

Oil-bearing Late Jurassic Oxfordian-Kimmeridgian sandstones of the Sgiath and Piper formations are of major economic importance in the Witch Ground Graben. They form the reservoirs in Scott, which in 1993 will be the largest producing North Sea oil field to come on stream for more than a decade. Together with Scott, the Piper, Saltire, Tartan, Highlander, Petronella, Rob Roy, and Ivanhoe fields contained almost 2 Bbbl of recoverable reserves in these formations. The Sgiath and Piper represent two phases of Late Jurassic transgression and regression, initially represented by paralic deposited sand culminating in a wave-dominated delta sequence. The history of the Sgiath and Piper formations is reviewed and lithostratigraphic and biostratigraphic correlations presented to illustrate the distribution of the reservoir sandstones.

Harker, S.D. (Occidental Petroleum (Caledonia) Ltd., Aberdeen (United Kingdom)); Mantel, K.A. (Narwhal, London (United Kingdom)); Morton, D.J. (Deminex U.K. Oil and Gas Ltd., London (United Kingdom)); Riley, L.A. (Paleoservices, Watford (United Kingdom))

1991-03-01

26

Haynesville sandstone reservoirs in the Updip Jurassic trend of Alabama  

SciTech Connect

Subsequent to the 1986 drilling of the 1 Carolyn McCollough Unit 1-13 well, which initiated production from the Frisco City sand of the Haynesville Formation in Monroe County, Alabama, seven Haynesville fields have been established in Covington, Escambia, and Monroe counties. Initial flow rates of several hundred BOPD are typical for wells in these fields, and maximum rates exceed 2000 BOPD in North Frisco City field. As of August 1993, these fields produced more than 3,400,000 bbl of oil and 4,000,000 mcf of gas from depths of 12,000 to 13,000 ft. Haynesville sandstone reservoirs are concentrated in two distinct areas: (1) an eastern area (Hickory Branch, North Rome, and West Falco fields; API oil gravity = 40{degrees}) in the Conecuh embayment and (2) a western area (Frisco City, North Frisco City, southeast Frisco City, and Megargel fields; API oil gravity = 58-59{degrees}) on the Conecuh ridge complex. Eastern fields are productive from Haynesville sandstone, which is not continuous with the two distinct, productive sandstone bodies in western fields, the Frisco City sand and the Megargel sand. Hydrocarbon traps are structural or combination traps associated with basement paleohighs. Reservoir bodies generally consist of conglomerate (igneous clasts in western fields; limestone clasts in eastern fields), sandstone (subarkose-arkose), and shale (some of which is red) in stacked fining-upward sequences. Shale at the tops of these sequences is bioturbated. These marine strata were deposited in shoal-water braid-delta fronts. Petrophysical properties differ between the two areas. Maximum and average permeability in western fields (k{sub max} = 2000 md; k{sub ave} = 850-1800 md) is an order of magnitude higher than in eastern fields. The distribution of diagenetic components, including a variety of carbonate minerals, evaporate minerals (anhydrite and halite in western fields), and carbonate-replaced pseudomatrix, commonly is related to depositional architecture.

Kugler, R.L.; Mink, R.M. [Geological Survey of Alabama, Tuscaloosa, AL (United States)

1994-09-01

27

Post-sedimentation transformations of Lower-Middle Jurassic sandstones of Great Caucases  

NASA Astrophysics Data System (ADS)

POST-SEDIMENTATION TRANSFORMATIONS OF LOWER-MIDDLE JURASSIC SANDSTONES OF GREAT CAUCASES M.I. Tuchkova Geological Institute Russian Academy of Sciences, Moscow, Russia tuchkova@geo.tv-sign.ru/ /Fax: (095) 2310443 Generalization of author’s and literature data is based on the analysis of sandstones cement and structure, composition and politypism of clay minerals and index of mica crystallinity. Fore zones of sandstone transformations are distinguished for Lower-Middle Jurassic sedimentary complexes of Great Caucases: 1) zone of neogenic chlorite and muscovite (index of crystallinity IC=1.0-2.0 mm) with wide development of epidote; solubility, blastic and spinulose structures, 2) zone of neogenic chlorite and sericite (IC=2.0-3.0 mm); solubility and spinulose structures, 3) zone of neogenic hydromica (IC=2.5-3.5 mm), kaolinite and/or montmorillonite minerals with microstylolite, conformal and conformal-regenerational contacts between grains, 4) zone of kaolinite and/or montmorillonite, mixed-layered and chlorite minerals with carbonate cement of pores filling, ferugination and conformal and microstylolite contacts between grains. Index of crystallinity of mica mineral IC=3.5-5.5 mm. In modern geological structure the region with most intensive transformations (zone 1) is traced in sandstones of here and there preserved Sinemurian-Lower Pliensbachian and Toarcian deposits in the belt of Jurassic deposits of the southern slope of Great Caucases. The extent of rock transformation increases northward and southward from the axial zone of Great Caucases. Represented zonality doesn’t depend on deposits thickness and doesn’t coincide with stratigraphycal borders. Post-sedimentation zonality of Jurassic deposits originated as a result of stress during the period of folding at the end of Middle and the beginning of Late Jurassic following the thrusting of northern flank of Great Caucases basin onto its axial part. The rocks of lowest part of Jurassic deposits of the southern slope, observed at the base of tectonically imbricated slices, were affected maximum transformations. They weren’t including in the subduction zone, but were only near this zone, so full sequence (up to metamorphism) of their transformations is not observed. The work was funded by RFBR, grant 02-05-64477.

Tuchkova, M. I.

2003-04-01

28

Kinematic implications of joint zones and isolated joints in the Navajo Sandstone at Zion National Park, Utah: Evidence for Cordilleran relaxation  

Microsoft Academic Search

At Zion National Park (ZNP) the landscape is a consequence of differential weathering of the Navajo Sandstone where closely spaced vertical joints constitute joint zones that erode to form regularly spaced (half kilometer) slot canyons striking 351°. Between these joint zones is a set of isolated joints striking 339°. Fracture interaction and horsetail\\/wing crack development indicate that the 339° striking

Christie M. Rogers; Douglas A. Myers; Terry Engelder

2004-01-01

29

Strength and failure characteristics of Jurassic Red-Bed sandstone under cyclic wetting-drying conditions  

NASA Astrophysics Data System (ADS)

Due to cyclic fluctuations of reservoir water levels, bank slopes in drawdown areas are subjected to wetting-drying cycles. In order to reasonably evaluate the stabilities of sandstone slopes in the drawdown area of the Three Gorges Reservoir, it is a primary premise to obtain the strength and failure characteristics of the sandstones undergoing wetting-drying cycles. In this paper, the conventional triaxial compression tests, ultrasonic velocity and porosity measurements and microstructural observations were conducted on Jurassic Red-Bed sandstone (JRS) specimens undergoing wetting-drying cycles. The results from the triaxial experiments indicate that the peak strengths of the JRS are dramatically reduced after the first wetting-drying cycle, and then remain approximately constant with increasing number of wetting-drying cycles. The failure modes of the JRS samples undergoing different wetting-drying cycles are all brittle failures under low confining pressures ( ? 15 MPa). The decrease in P-wave velocity and increase in porosity with increasing number of wetting-drying cycles reveals the raise of damage level of the sandstone specimens, which is the main reason for the decline of peak strength. Detailed microstructural analysis has shown obvious argillization phenomena after undergoing wetting-drying cycles, which weakens the cements between grains in the sandstone and increases the damage of the sandstone.

Zhang, Zhenhua; Jiang, Qinghui; Zhou, Chuangbing; Liu, Xinting

2014-08-01

30

Diagenetic history of fluvial and lacustrine sandstones of the Hartford Basin (Triassic Jurassic), Newark Supergroup, USA  

NASA Astrophysics Data System (ADS)

The early introduction of clays into continental sandstones has been attributed to mechanical infiltration by percolation of clay-rich surface waters into grain framework or cutans formed from pedogenic processes. The discovery of pedogenic mud aggregates as traction-load mud in ancient fluvial deposits suggests that permeability and porosity of terrigenous sandstones can be influenced at deposition and control early diagenetic patterns. This study compares diagenesis in fluvial (subaerially exposed) sandstones with lacustrine (subaqueous) sandstones in a Triassic-Jurassic continental rift basin (Hartford Basin, Newark Supergroup). Diversity of diagenetic minerals and sequence of diagenetic alteration can be directly related to depositional environment. The fluvial sandstones in the New Haven Arkose, East Berlin Formation, and Shuttle Meadow Formation of the Hartford Basin are dominated by concretionary calcite and early calcite cement, infiltrated clays (illite-smectite), pedogenic mud aggregates (smectite and illite-smectite), grain coating clays (illite/hematite, illite-chlorite/hematite), quartz overgrowths, late stage carbonate cements (calcite, ferroan calcite), pore-filling clays (illite, kaolinite with minor amounts of smectite, smectite-chlorite, illite-smectite) and hematite. However, pedogenic processes in these fluvial sandstones retarded the development of quartz and feldspar overgrowths, and carbonate authigenesis, as well as the quality of diagenetically enhanced porosity. Dark gray-black lacustrine (subaqueous) sandstones and mudrocks in the East Berlin and Shuttle Meadow Formations are dominated by pyrite, concretionary dolomite and early dolomite cement, radial grain coating clays (smectite-chlorite, illite-smectite), late stage carbonate cements (dolomite, ferroan dolomite, ankerite), albite and pore-filling clays (smectite-chlorite, illite-smectite, illite-chlorite). Clay minerals exist as detrital, mechanically infiltrated, and neoformed clay. The fluvial sandstones in the New Haven Arkose are dominated by illite. The East Berlin and Shuttle Meadow Formations are dominated by illite in the fluvial sequences and smectite-chlorite and illite-smectite in the lacustrine sandstones. Dolomite, ferroan dolomite, and ankerite are restricted to lacustrine sandstones, whereas calcite and ferroan calcite to fluvial sandstones. Albite predominantly precipitated in lacustrine rather than fluvial environments through intergranular dissolution of plagioclase by acidic meteoric water, dissolution of unstable mafic minerals, and sodium-rich brines and evaporites developed from groundwater. Albitization and carbonate cementation are the most pronounced late stage diagenetic processes affecting both types of Hartford sandstones.

Wolela, A. M.; Gierlowski-Kordesch, E. H.

2007-04-01

31

Diagenesis of a tight gas formation: Jurassic Cotton Valley Sandstone, East Texas basin  

SciTech Connect

The Upper Jurassic Cotton Valley Sandstone is a thick siliciclastic unit in the East Texas basin. Along the eastern flank of the basin, natural gas is produced from Cotton Valley reservoirs characterized by low porosity and permeability, which have been stimulated by massive hydraulic fracturing. Cotton Valley sandstones are generally very fine-grained, well-sorted quartz arenites and subarkoses. Principal framework constituents are monocrystalline quartz and feldspars. The sandstones have had a complex diagenetic history and are cemented by authigenic quartz, calcite, phyllosilicates, and iron oxides. The most common paragenetic sequence of pore-fill minerals was (1) development of clay coats on grains, (2) formation of syntaxial overgrowths, (3) dissolution of unstable grains followed by precipitation of phyllosilicates, (4) precipitation of calcite in relict primary and secondary pores, and (5) replacement of framework grains by calcite resulting in a poikilotopic texture. Cotton Valley sandstones are classified by R-mode factor analysis into three groups that can be related to porosity characteristics. Therefore, the groups can be used to predict potential reservoir rock. Type I rocks are tightly cemented by quartz and calcite and make poor reservoirs. Type II rocks have a high phyllosilicate content and abundant microporosity, and may produce gas. Type III rocks have a high content of unstable grains and have well-developed secondary porosity, which can be of reservoir quality. Depositional facies controlled the diagenesis of the Cotton Valley Sandstone.

Wescott, W.A.

1984-09-01

32

Navajo Peak  

USGS Multimedia Gallery

A view of Navajo Peak from Rainbow Point in Bryce Canyon National Park. Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolomite that caps them and the s...

33

Navajo Dome  

USGS Multimedia Gallery

Navajo Dome, one of the more notable features within Capitol Reef National Park. Capitol Reef is primarily made up of sandstone formations within the Waterpocket Fold, monocline that extends nearly 100 miles. A monocline is a step-like fold in rock strata that can resemble an enormous wrinkle in the...

34

Major discoveries in eolian sandstone: facies distribution and stratigraphy of Jurassic Norphlet sandstone, Mobile Bay, Alabama  

Microsoft Academic Search

Recent exploratory and development drilling in Mobile Bay, southwest Alabama, has proven prolific gas production from the Norphlet sandstone at depths greater than 20,000 ft with individual well tests of 10-27 MMCFGD. Excellent reservoir qualities are a function of preserved primary porosity and permeability developed in an eolian setting. In Mobile Bay, thick eolian sediments (200-600 ft) lie directly on

Joel B. Levy

1985-01-01

35

Major discoveries in eolian sandstone: facies distribution and stratigraphy of Jurassic Norphlet sandstone, Mobile Bay, Alabama  

SciTech Connect

Recent exploratory and development drilling in Mobile Bay, southwest Alabama, has proven prolific gas production from the Norphlet sandstone at depths greater than 20,000 ft with individual well tests of 10-27 MMCFGD. Excellent reservoir qualities are a function of preserved primary porosity and permeability developed in an eolian setting. In Mobile Bay, thick eolian sediments (200-600 ft) lie directly on Pine Hill or Louann evaporites. Three facies of the Norphlet have been recognized: (1) a thin (20-30 ft) basal wet sand flat or sabkha facies, (2) a massive dune facies, and (3) a thin (30-40 ft) upper marine reworked facies. The wet sand flat or sabkha facies is characterized by irregular to wavy horizontally bedded sandstone associated with adhesion ripples. It is probably sporadically developed in response to localized wet lows during earliest Norphlet deposition. The majority of the Norphlet section is characterized by massive wedge-planar and tabular-planar cross-stratified sandstone, interpreted to be stacked dune and dry interdune deposits. Individual dune sets range in height from a few feet to 90 ft. Cross-bed sets exhibit internal stratification patterns similar to large- and small-scale dunes described by G. Kocurek and R. Dott, Jr. The marine reworked facies is characterized by structureless to diffuse or wavy laminated sandstone that reflects a reworking of the dune deposits by the ensuing Smackover transgression. Reservoir quality is affected by textural properties determined by depositional processes associated with these various facies. Diagenetic patterns further reducing reservoir quality occur in the depositionally less-porous sediments. Dune facies sediments exhibit the best reservoir qualities. Variations of reservoir quality within the dune facies are related to dune height and dune versus interdune accumulations.

Levy, J.B.

1985-02-01

36

Petrology and diagenesis of Upper Triassic and Lower Jurassic graben-fill sandstones of Jameson land basin, central east Greenland  

SciTech Connect

Sands of the Upper Triassic-Lower Jurassic Kap Stewart and Lower Jurassic Neill Klinter Formations were deposited during the early development of a major Jurassic rift basin. Depositional environments have been interpreted as alluvial fan, fluvial, and deltaic for the Kap Stewart, and as tidal estuary for the Neill Klinter. Most of these sandstones are fine to medium-grained quartz and subarkosic wackestones. Clay matrix is abundant and comprises mostly diagenetic kaolinite, illite, and complex clay mixtures derived from the breakdown of labile framework grains, especially plagioclase and biotite. Early emplacement of carbonate cement in some sandstones prevented development of diagenetic clay matrix. The carbonate cement is poikilotopic and constitutes up to 30% of some samples. The current high level of maturity indicated by the quartz-feldspar-lithic composition for these sandstones results from selective diagenetic decomposition of labile grains. The original, more feldspathic compositions reflect less maturity and an earlier stage of basin fill than the Middle Jurassic, high-porosity arenites, which also contain abundant quartz and up to 25% feldspar. Because of Upper Triassic and Lower Jurassic sands were deposited in continental and low-energy marine environments, they likely underwent greater in-situ alteration but less winnowing of labile grains than the overlying Middle Jurassic sands deposited in higher energy marine settings.

Davee, K.W.; Mansfield, C.F.

1986-05-01

37

Diagenetic quartzarenite and destruction of secondary porosity: An example from the Middle Jurassic Brent sandstone of northwest Europe  

SciTech Connect

Significant amounts of feldspar have been dissolved from Middle Jurassic sandstone oil reservoirs in the North Sea (northwest Europe) during burial diagenesis Sandstones of the Middle Jurassic Brent Group become increasingly quartzose with increasing burial depth. At Statfjord field (2500 m depth), sandstones are arkose to subarkose; at Hutton field (3050 m depth), they are subarkose to quartzarenite, and at Lyell field (3500 m depth), sandstones are typically quartzarenite. In spite of extensive feldspar dissolution, the abundance of secondary porosity due to feldspar dissolution is similar for all fields, averaging 2.9% of the total rock volume. Thus, far more feldspar has been dissolved than is recorded as secondary porosity. The limit on preservation of secondary porosity may be largely the effect of the mechanical strength of the rock. An excessive number of large secondary pores lowers the rock strength below the point at which the rock can withstand overburden stress, thus causing collapse of some of the secondary pores.

Harris, N.B. (Conoco Inc., Ponca City, OK (USA))

1989-04-01

38

Diagenetic quartzarenite and destruction of secondary porosity: An example from the Middle Jurassic Brent sandstone of northwest Europe  

NASA Astrophysics Data System (ADS)

Significant amounts of feldspar have been dissolved from Middle Jurassic sandstone oil reservoirs in the North Sea (northwest Europe) during burial diagenesis. Sandstones of the Middle Jurassic Brent Group become increasingly quartzose with increasing burial depth. At Stafford field (2500 m depth), sandstones are arkose to subarkose; at Hutton field (3050 m depth), they are subarkose to quartzarenite; and at Lyell field (3500 m depth), sandstones are typically quartzarenite. In spite of extensive feldspar dissolution, the abundance of secondary porosity due to feldspar dissolution is similar for all fields, averaging 2.9% of the total rock volume. Thus, far more feldspar has been dissolved than is recorded as secondary porosity. The limit on preservation of secondary porosity may be largely the effect of the mechanical strength of the rock. An excessive number of large secondary pores lowers the rock strength below the point at which the rock can withstand overburden stress, thus causing collapse of some of the secondary pores.

Harris, Nicholas B.

1989-04-01

39

Crouching theropod and Navahopus sauropodomorph tracks from the Early Jurassic Navajo Sandstone of USA  

E-print Network

these wet peri- ods, animal and plant life flourished, but dune migration con- tinued at about the same rate is to describe a new theropod trackway that shows the animal to crouch down on the sand and then continue up

Loope, David B.

40

Depositional environments and hydrocarbon occurrence of upper Jurassic Cotton Valley sandstones, Mississippi, Louisiana, and Texas  

SciTech Connect

The sandstones of the Kimmeridgian (Jurassic) upper Cotton Valley Formation of Mississippi, northern Louisiana, and eastern Texas were deposited on a stable subsiding shelf. These sands are regressive and are part of a complex of deltaic and marine systems. They are quartz-rich and exhibit a variety of sedimentary structures. Cotton Valley fluvial-deltaic systems drained Paleozoic and younger highlands to the north and northwest, depositing sands on the shelf where they were subsequently reworked. Three depositional environments have been interpreted for these sands in Mississippi: (1) a constructive delta in the west-central part of the state, (2) a destructive delta in the east-central part of the state, and (3) an interdeltaic system in central Mississippi between the other systems. In northern Louisiana and northeastern Texas, the following environments have been interpreted: a proximal destructive delta system in northwest Louisiana and northeast Texas and another delta system in northeastern Louisiana with an interdeltaic system consisting of barrier beaches and barrier bars located centrally between them. Production is controlled by porosity and permeability barriers, fault traps, and salt- and basement-induced structures.

Kornfeld, I.

1985-02-01

41

Kinematic implications of joint zones and isolated joints in the Navajo Sandstone at Zion National Park, Utah: Evidence for Cordilleran relaxation  

NASA Astrophysics Data System (ADS)

At Zion National Park (ZNP) the landscape is a consequence of differential weathering of the Navajo Sandstone where closely spaced vertical joints constitute joint zones that erode to form regularly spaced (half kilometer) slot canyons striking 351°. Between these joint zones is a set of isolated joints striking 339°. Fracture interaction and horsetail/wing crack development indicate that the 339° striking joint set is younger than the 351° striking joint zones, despite the lateral extent of stress reduction shadows in the vicinity of the large-scale joint zones. In addition to an older, less pervasive, ˜020° joint set, this sequence of jointing records a counterclockwise rotation of the regional extension directed from WNW to WSW in the Navajo Sandstone at ZNP. ZNP is located at the western margin of the Colorado Plateau, ˜100 km east of the major normal faults of the northeastern central Basin and Range subprovince. Extension within the eastern central Basin and Range initiated during the Miocene and exhibited a WSW extension direction [, 1971; , 1988; , 2000]. The correlation between nearby Basin and Range extension and the extension direction for the 351° tending joint zones of ZNP is so close that the jointing at ZNP is interpreted as evidence for modest, yet pervasive Basin and Range extension in the western margin of the Colorado Plateau.

Rogers, Christie M.; Myers, Douglas A.; Engelder, Terry

2004-02-01

42

Investigation of exfoliation joints in Navajo sandstone at the Zion National Park and in granite at the Yosemite National Park by tectonofractographic techniques  

SciTech Connect

Tectonofractographic techniques have been applied to the study of joint exfoliation in the Navajo sandstone at Zion National Park and in the granite at Yosemite National Park. New types of fracture surface morphologies have been observed which enabled the discerning of incipient joints and consequent fracture growth in these rocks. Incipient jointing in the sandstone is mostly manifested by elliptical and circular fractures (meters to tens meters across) initiating from independent origins. They interfere with each other and grow to larger circular fractures producing exfoliation surfaces up to hundreds of meters across. Less frequently, series of large concentric undulations demonstrate the propagation of a large fracture front producing exfoliation from an individual origin. One such fracture front reveals refraction of undulations at a layer boundary. Certain en echelon fringes surround the joint mirror plane with well defined rims of en echelons and hackles which enable the determination of the tensile fracture stress, {sigma}f. Arches in Zion National Park are ubiquitous in shape and size, revealing stages in their evolution by a mechanical process, which was associated with exfoliation, but independent of local faulting. Exfoliation and arching mostly occurred on vertical surfaces of N-NNW and NE sets of prominent joints, but there are also deviations from this general trend. In Yosemite National Park large exfoliations (hundreds of meters in size) developed on the El Capitan cliff by the interaction and merging of many previous smaller incipient joints that vary in size from meters to tens of meter.

Bahat, D.; Grossenbacher, K.; Karasaki, K.

1995-04-01

43

Sandstone Texture  

USGS Multimedia Gallery

Views along the Navajo Loop Trail in Bryce Canyon National Park. Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolomite that caps them and the sandston...

44

Navajo Nation  

NSDL National Science Digital Library

This site is an informational website about Navajo culture. Information includes the meaning of the Navajo flag, the origin of the Navajo people, the four worlds of the Navajo, the significance of the four directions (north, south, east, west) to the Navajo, language, family and culture. Users may also follow links to information on other Native American cultures, an ancient civilization index, and an alphabetical list of all files in the Crystalinks website.

Crystal Ellie

45

Field guide to sedimentary structures in the Navajo and Entrada sandstones in southern Utah and northern Arizona: Chapter in Field-trip guidebook, 100th annual meeting, The Geological Society of America, Phoenix, Arizona, October 26-29, 1987  

USGS Publications Warehouse

This field-trip guide describes the common sedimentary structures that occur in eolian sands. The outcrops that are described occur in the Navajo and Entiaia Sandstones between the areas of Page, Arizona and St. George, Utah (figure I), but the sedimentary structures of these two sandstones are typical of most eolian deposits. The main part of the guide discusses the geologic setting and the origin of the various structures, and the road log discusses which structures are best displayed at selected outcrops.

Rubin, David M.; Hunter, Ralph E.

1987-01-01

46

Bryce Canyon's Navajo Loop Trail  

USGS Multimedia Gallery

Views along the Navajo Loop Trail in Bryce Canyon National Park. Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolomite that caps them and the sandston...

47

Haynesville sandstone reservoirs in the updip-Jurassic trend of Alabama  

SciTech Connect

Since the 1986 drilling of the 1 Carolyn McCollough Unit 1-13 well, which initiated production from the Frisco City sandstone of the Haynesville Formation in Monroe County, Alabama, seven Haynesville fields have been established in Covington, Escambia, and Monroe Counties. Initial flow rates of several hundred BOPD are typical in wells in these fields, and maximum rates exceed 2,000 BOPD in North Frisco City field. As of August 1993, these fields had produced more than 3,400,000 bbl of oil and 4,000,000 Mcf of gas from depths of 12,000 to 13,000 ft. Haynesville sandstone reservoirs are concentrated in two distinct areas: (1) an eastern area (Hickory Branch, North Rome, and West Falco fields; API oil gravity = 40{degrees}) in the Conecuh embayment and (2) a western area (Frisco City, North Frisco City, southeast Frisco City, and Megargel fields, API oil gravity = 58-59{degrees}) on the Conecuh ridge complex. Eastern fields are productive from Haynesville sandstone, which is not continuous with the two distinct, productive sandstone bodies in western fields, the Frisco City sandstone and the Megargel sandstone. Hydrocarbon traps are structural or combination traps associated with basement paleohighs. Reservoir bodies generally consist of conglomerate (igneous clasts in western fields; limestone clasts in eastern fields), sandstone (subarkose-arkose), and shale (some of which is red) in stacked upward-fining sequences. Shale at the tops of these sequences is bioturbated. These marine strata were deposited in shoal-water braid-delta fronts. Maximum and average permeability in western fields (k{sub max} = 2,000 md; k{sub ave} = 850-1,800 md) is an order of magnitude higher than that in eastern fields. The distribution of diagenetic components, including a variety of carbonate minerals, evaporite minerals (anhydrite and halite in western fields), and carbonate-replaced pseudomatrix, commonly is related to depositional architecture.

Kugler, R.L.; Mink, R.M. [Geological Survey, Tuscaloosa, AL (United States)

1994-12-31

48

Role of halite in the evolution of sandstone porosity, upper Jurassic Norphlet Formation, Mississippi salt basin  

Microsoft Academic Search

Analysis of petrographic point-count data, cement paragenesis, and scanning electron microscopy examination of pores has shown that poikilitic halite cement in sandstones of the Norphlet Formation in a core from Wayne County, Mississippi, formed following cementation by quartz, feldspar, dolomite, and anhydrite. Intergranular volume ranges from 26 to 42%, averaging 35%, indicating that an average of 10% of the rock

C. J. Schenk; J. W. Schmoker

1993-01-01

49

Navajo Timeline  

NSDL National Science Digital Library

This searchable timeline describes Navajo history from 1200 BC through the year 2002. Throughout the timeline, historical events of the Navajo are described and paired with world history. Useful links to topics concerning the Navajo can be found in the later periods within the timeline. Users can search the timeline using a pull-down menu of time periods.

Lapahie Harrison

50

Role of halite in the evolution of sandstone porosity, upper Jurassic Norphlet Formation, Mississippi salt basin  

SciTech Connect

Analysis of petrographic point-count data, cement paragenesis, and scanning electron microscopy examination of pores has shown that poikilitic halite cement in sandstones of the Norphlet Formation in a core from Wayne County, Mississippi, formed following cementation by quartz, feldspar, dolomite, and anhydrite. Intergranular volume ranges from 26 to 42%, averaging 35%, indicating that an average of 10% of the rock volume was lost to compaction, and a further 10-15%, was lost to cementation prior to halite cementation, assuming a depositional porosity of about 45%. Most halite occurs as intergranular cement, but some halite is present as intragranular cement within framework feldspars and lithic fragments. Halite is easily removed from a sandstone during coring, slabbing, and thin-section preparation techniques that do not use oil-based fluids and muds, so the amount of porosity in these samples that is a product of artificial removal of halite is unknown. Although the present and former distribution of halite is poorly known, natural halite dissolution could have produced about 20% secondary porosity in the Norphlet Formation at depth in this part of the Mississippi Salt basin.

Schenk, C.J.; Schmoker, J.W. (Geological Survey, Denver, CO (United States))

1993-09-01

51

Navajo Indians  

NSDL National Science Digital Library

Let's learn about Utah History! Let's learn about the Navajo Indians. Learning Objective After reading and researching information about the Navajo tribe, students will be able understand the culture and traditions of this tribe and make comparisons to their own culture, by researching, writing about and creating Navajo jewelry and completing a cultural comparison worksheet. Grades 3 4th Grade Content Area(s) Social Studies Content Targets History, culture ...

Keshia Chamberlain

2009-11-28

52

Navajo (Dine)  

NSDL National Science Digital Library

This website consists of a fact sheet that provides a brief account of the ancient and modern history the Navajo peoples. The text discusses the Navajo transition from nomadic hunting and gathering people in the early Spanish period to the sheep herding, blanket-weaving peoples of the nineteenth century. Links within the text lead to a glossary of terms and additional information about the history and cultural heritage of the Navajo peoples.

Grahame John

53

THE NAVAJOS.  

ERIC Educational Resources Information Center

A STUDY OF NAVAJO AMERICAN INDIANS IS PRESENTED. INCLUDED ARE THE TRIBE'S HISTORY, RESOURCES, ECONOMIC SITUATION, AND WAYS TO IMPROVE IT. THE NAVAJOS ARE DIFFERENT FROM OTHER AMERICAN INDIAN TRIBES IN THAT THEY ARE RAPIDLY INCREASING, THEY HAVE INCREASED THE SIZE OF THEIR RESERVATION, THEY STILL LIVE IN ISOLATION AND IN A PRIMITIVE FASHION, AND…

Navajo Tribe Public Relations and Information Dept., Window Rock, AZ.

54

Degradation processes and consolidation of Late Jurassic sandstone dinosaur tracks in museum environment (Museum of Lourinhã, Portugal)  

NASA Astrophysics Data System (ADS)

The current study aims to conciliate conservation and restoration museology diagnosis with paleontological and geological curational needs and has, as subject of study, dinosaur footprints (vertebrates fossils). The footprints have been being exposed since 2004 in the paleontology hall of the Museum of Lourinhã, Portugal, and are part of a important paleontological collection of Late Jurassic vertebrate fossils from Lourinhã Formation. Presently, it is considered a unique heritage in danger of disappearing due to high decay level of disaggregation of its geological structure. The dinosaur footprints, (ML557) found, more precisely, on a coastline cliff in Lourinhã, Porto das Barcas, Lagido do Forno (coordinate 39° 14. 178'N, 9° 20. 397'W), Jurassic period, on the 5th of June 2001, by Jesper Milàn. This cliff of high slope presents sedimentary stratigraphic characteristics of a sandstone/siltstone of gray and red colors, by the '' Munsell scale and Color Chart''. Geological the tracks are Late Jurassic in age, and colected in the Lourinhã Formation, Praia Azul Member, of the Lusitanian Basin. There are three natural infills tridactyl tracks, possibly ascribed to ornithopod, a bipedal herbivore, resultant of a left foot movement, right and left. Footprints have 300-400mm of wide and 330-360mm of height with round fingers, which are elongated due to some degradation/erosion. In 2001, the footprints were collected from the field, cleaned, consolidated and glued in the laboratory of the Museum of Lourinhã before being exhibited in a museum display. Stone matrix was removed and a consolidation product applied, probably a polyvinyl acetate, of the brand Plexigum. The footprint with broken central digit was glued with an epoxy resin, Araldite. Both applied products were confirmed by analysis of µ-FTIR (Fourier Transform Infrared Spectroscopy) and both presented colour change and detachment surface problems. After collecting and storing, in 2004, footprints were transferred to the current public paleontology hall, ground floor, placed on the floor without any protection framework or environmental control (temperature and relative humidity). Presently, footprints show major geological structure disintegration/deterioration problems and were diagnosed several pathologies :"Blistering", "Powdering", "Exfoliation"' as well as "Dirt", "Fracture"', "Inscriptions", "Consolidates" and "Adhesives". Several laboratorial analysed were conducted to evaluate the presence of salts. Moreover a microclimatic study was conducted inside the museum to evaluate the influence of thermohygrometric parameters on the decay processes observed. As future procedures, all tracks will suffer a superficial cleaning (dust removal) with brush without any solvent and also the application of a consolidant aiming to restore some coehesion of these footprints. Since stone consolidation is a very risky intervention, several laboratory tests are being conducted with stone samples taken from the same layer and location from Porto das Barcas and using different commercial consolidation products.

Leal, Sofia; mateus, Octavio; Tomas, Carla; Dionisio, Amelia

2014-05-01

55

Diagenesis of Eolian and fluvial feldspathic sandstones, Norphlet formation (upper Jurassic), Rankin County, Mississippi, and Mobile County, Alabama  

Microsoft Academic Search

Norphlet sandstones in seven cores from Mississippi and Alabama are arkoses and subarkoses deposited in eolian-dune, interdune, and fluvial environments. Similar to the deeply buried (> 5 km) Tertiary feldspathic sandstones of the Gulf basin, all detrital plagioclase that survived dissolution has been albitized. Fluvial red sandstone lost all initial porosity by the introduction of preburial pedogenic calcite and compaction.

L. S. Land; L. E. Mack

1987-01-01

56

Reservoir characterization of tight gas sand: Taylor sandstone (upper Cotton Valley group, upper Jurassic), Rusk County, Texas  

Microsoft Academic Search

An integrated petrographic, sedimentologic, and log analysis study of the Taylor sandstone in Rusk County, Texas, was conducted to understand the geologic controls on reservoir performance and to identify pay zones for reserves calculations. The Taylor sandstone interval consists of tightly cemented, fine-grained quartzose sandstones interbedded with mudstones, siltstones, and carbonates that occur in upward-coarsening sequences. Helium permeability rarely exceeds

C. L. Vavra; M. H. Scheihing; J. D. Klein

1989-01-01

57

Snow on the Navajo Loop Trail  

USGS Multimedia Gallery

Views along the Navajo Loop Trail in Bryce Canyon National Park. Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolomite that caps them and the sandston...

58

Hoodoo on the Navajo Loop Trail  

USGS Multimedia Gallery

Views along the Navajo Loop Trail in Bryce Canyon National Park. Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolomite that caps them and the sandston...

59

Cedars on the Navajo Loop Trail  

USGS Multimedia Gallery

Views along the Navajo Loop Trail in Bryce Canyon National Park. Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolomite that caps them and the sandston...

60

Rock doughnut and pothole structures of the Clarens Fm. Sandstone in the Karoo Basin, South Africa: Possible links to Lower Jurassic fluid seepage  

NASA Astrophysics Data System (ADS)

South Africa has a wealth of sandstone landforms, yet many of these have not been examined in detail to expand knowledge on their morphology and process origins. Here we present data on primary morphological statistics, rock hardness, surface roughness and petrographic investigations of rock doughnuts and associated pothole structures in Golden Gate Highlands National Park (GGHNP) and in the Witkop III complex, with the aim of using such data and field observations to argue their likely origins. Schmidt hammer R-values indicate consistently harder doughnut rims (mean = 48.7; n = 150) than the enclosed potholes (mean = 37.8; n = 150) and surrounding sandstone platform (mean = 39.7; n = 250). The petrography of Clarens Fm. Sandstone shows that the typical whitish sandstone is affected by intense chemical weathering. Pothole rims and the irregular reddish crust typical of the Witkop III outcrops show a secondary cementation by microcrystalline silica. Although preservation of old land surfaces is difficult to prove, small and circular pipe structures filled with calcite-cemented sand are present locally surrounding the Witkop III hydrothermal complex, and represent conduits for fluidized sand. Based on the morphologies of the Witkop III summit with the associated potholes and pipes, we hypothesize that they are remnants of morphologies created by Jurassic fluid seepage, with a superimposed and secondary silica cementation. Given that fluidization structures evidently occur in Clarens Fm. Sandstone, as is the case at Witkop, such mechanisms could possibly have contributed to the observed rock doughnut structures elsewhere on Clarens Fm. Sandstones, such as at the GGHNP where the rock doughnut morphological attributes are typical to landforms originating from fluid venting.

Grab, Stefan; Svensen, Henrik

2011-08-01

61

Navajo Country  

NSDL National Science Digital Library

This map of the Navajo Nation illustrates settlements, landforms, water features, parks, forests, and neighboring Indian reservations. The map index provides links to additional information about some of these features.

Lapahie Harrison

62

Conversational Navajo  

NSDL National Science Digital Library

Most of the Din4 (Navajo) students now entering Kindergarten do not speak the Din4 language. And with the majority of parents wanting Din4 language classes for their children, this program was put together. This is also a School Board and Bilingual Education Consensus Committee mandate.

San Juan School District

63

Erosional remnants and adjacent unconformities along an eolian-marine boundary of the Page Sandstone and Carmel Formation, Middle Jurassic, south-central Utah  

SciTech Connect

Sandstone ridges along the marine-eolian boundary of the Middle Jurassic Page Sandstone (eolian) with the lower Carmel Formation (restricted marine) in south-central Utah have been identified as erosional remnants consisting of strata of siliciclastic sabkha and eolian origin. The ridges lie within two distinct units of the Thousand Pockets Tongue of the Page. Two equally plausible models explain the genesis of these ridges. One model involves (1) early cementation of eolian and sabkha strata, (2) wind erosion leading to development of yardangs and unconformities, (3) yardang tilting due to evaporite dissolution, and (4) renewed deposition and burial. The alternative model explains ridge development through (1) subsidence, with tilting, of eolian and sabkha strata into evaporites due to loading from linear dunes, (2) evaporite dissolution and unconformity development, and (3) renewed deposition and burial. These models provide important clues about the nature of a missing part of the rock record. Reconstruction of units that were deposited but later eroded improves paleogeographic interpretation and here indicates that the Carmel paleo-shoreline was considerably farther to the northwest than previously believed.

Jones, L.S.; Blakey, R.C. (Univ. of Northern Arizona, Flagstaff, AZ (United States). Dept. of Geology)

1993-09-01

64

Disseminated `jigsaw piece' dolomite in Upper Jurassic shelf sandstones, Central North Sea: an example of cement growth  

E-print Network

: an example of cement growth during bioturbation? JAMES P. HENDRY*1 , MARK WILKINSON , ANTHONY E. FALLICKà crystals and consequent cementation of the grain framework. Continued exchange of Mg2+ and Ca2 on calcite cementation in marine sandstones in recent years has greatly improved our understanding

Haszeldine, Stuart

65

Reservoir characterization of tight gas sand: Taylor sandstone (upper Cotton Valley group, upper Jurassic), Rusk County, Texas  

SciTech Connect

An integrated petrographic, sedimentologic, and log analysis study of the Taylor sandstone in Rusk County, Texas, was conducted to understand the geologic controls on reservoir performance and to identify pay zones for reserves calculations. The Taylor sandstone interval consists of tightly cemented, fine-grained quartzose sandstones interbedded with mudstones, siltstones, and carbonates that occur in upward-coarsening sequences. Helium permeability rarely exceeds 0.1 md, and porosity is rarely greater than 10%. Relationships between porosity and permeability are diffuse because of a string diagenetic overprint. Six major rock types or petrofacies are distinguished on the basis of pore type and dominant cement mineralogy. Three sandstone petrofacies - primary macroporous quartz cemented, moldic macroporous quartz cemented, and microporous clay cemented - have reservoir potential. Although these petrofacies have similar porosities and permeabilities, fluid saturations differ considerably due to differences in pore geometry as indicated by petrographic and capillary pressure analyses. These three reservoir-quality petrofacies can each be identified directly on wireline logs by applying cutoffs to the porosity and normalized gamma-ray logs.

Vavra, C.L.; Scheihing, M.H.; Klein, J.D.

1989-03-01

66

Mixing zone origin of 13C-depleted calcite cement: Oseberg Formation sandstones (Middle Jurassic), Veslefrikk Field, Norway  

NASA Astrophysics Data System (ADS)

Carbonate cement is one of the more volumetrically important diagenetic components of sandstones. The sandstones of the fan delta facies of the Oseberg Formation (Brent Group) in Veslefrikk field contain abundant carbonate cemented zones, commonly comprised of 30-40% carbonate by volume. The cement is predominantly poikilotopic, ferroan calcite, with minor amounts of ankerite and siderite. Petrographie evidence for high porosities at the time of calcite precipitation indicate that cementation occurred under shallow burial conditions, probably less than 500 m. Crosscutting textural relations demonstrate that calcite cementation was predated and postdated by tectonic stresses that produced both grain fractures and through-going fractures, respectively. In the non-calcite cemented parts of the formation major compaction, pressure solution, feldspar dissolution, and cementation by quartz and clays postdated calcite cementation. The oxygen isotopic composition of the calcite averages - 8.5% 0 (PDB), and shows large variations within individual calcite cemented zones (up to 10% 0 in ? 18O). The depleted and variable oxygen isotopic composition, in conjunction with evidence for shallow precipitation, indicate calcite growth occurred in a mixing zone environment, variably influenced by meteoric water. Isotopic variation within many individual cemented zones is symmetric about the center of the zones, indicating that growth of the cemented zones was from the center outwards in a concretionary fashion. The high Fe and Mn content of the calcite (avg. 1.3 mol% Fe, avg. 0.4 mol% Mn) and its association with disseminated pyrite indicate that porewater was reducing during precipitation. Carbon isotopic data (avg. ?13C = - 15.7% 0 PDB, range = - 3 to - 3 1% 0) show that major amounts of organic carbon, at least partly derived by sulfate reduction of biogenic methane, were incorporated in the calcite. Other documented occurrences of early, 13C-depleted carbonate-cemented sandstones are similar to the carbonate cement in Veslefrikk Field in their association with methane oxidation and their low temperature formation. However, the cement at Veslefrikk differs in its mineralogical and morphological occurrence and in the fact that it formed from a porewater strongly influenced by mixing with meteoric water. Key geologic factors that determined the traits of calcite cement in Veslefrikk Field are the combination of nearshore marine deposition of permeable sands, close proximity of organic-rich marine muds, and variations in relative sea level, which provided opportunities for invasion by meteoric water. These geologic factors had a similar impact on other Brent Group deltaic sandstones and are believed to explain some of the differences between the geochemistry of carbonate cements in deltaic and shelf sandstones of the North Sea and elsewhere.

Lundegard, Paul D.

1994-06-01

67

Diagenesis of Eolian and fluvial feldspathic sandstones, Norphlet formation (upper Jurassic), Rankin County, Mississippi, and Mobile County, Alabama  

SciTech Connect

Norphlet sandstones in seven cores from Mississippi and Alabama are arkoses and subarkoses deposited in eolian-dune, interdune, and fluvial environments. Similar to the deeply buried (> 5 km) Tertiary feldspathic sandstones of the Gulf basin, all detrital plagioclase that survived dissolution has been albitized. Fluvial red sandstone lost all initial porosity by the introduction of preburial pedogenic calcite and compaction. Initial porosity of eolian sands was reduced by compaction to an average of 29%; and later by cementation by quartz, carbonates, anhydrite, halite, K-feldspar, and illite. Quartz and anhydrite cements precipitated between 90/sup 0/ and 100/sup 0/C (approximately 2.3 km deep), carbonates and halite cements formed below 120/sup 0/C (< 3 km), and late-stage illite cement formed between 130/sup 0/ and 150/sup 0/C (4-5 km deep). Cements are patchy, and some, especially quartz and anhydrite, are texture-selective, being more abundant in coarser laminae. Secondary porosity, which makes up approximately half the porosity in thin sections, formed by dissolution of detrital grains (feldspar, rock fragments) and cements (anhydrite, carbonate, halite). Reservoir bitumen records an early phase of oil entrapment. Reservoir quality is influenced by the abundance of reservoir bitumen and thread-like illite, both of which bridge pores. Isotopic data suggest that during the first 30 to 40 m.y. of burial, subsurface diagenesis of the Norphlet Formation was dominated by deep-circulating, hot, meteoric water. This phenomenon may be characteristic of the early diagenetic history of rifted basins. 10 figures, 5 tables.

McBride, E.F.; Land, L.S.; Mack, L.E.

1987-09-01

68

Two Bridges Formation on the Navajo Loop Trail  

USGS Multimedia Gallery

Views along the Navajo Loop Trail in Bryce Canyon National Park. Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolomite that caps them and the sandston...

69

Navajo Electrification Demonstraiton Project  

SciTech Connect

This is a final technical report required by DOE for the Navajo Electrification Demonstration Program, This report covers the electric line extension project for Navajo families that currently without electric power.

Larry Ahasteen, Project Manager

2006-07-17

70

Strong Navajo Marriages  

ERIC Educational Resources Information Center

The purpose of this qualitative study, conducted in two Navajo Nation chapters, was to learn what makes Navajo marriages strong because no research has been done on this topic. Twenty-one Navajo couples (42 individuals) who felt they had strong marriages volunteered to participate in the study. Couples identified the following marital strengths:…

Skogrand, Linda; Mueller, Mary Lou; Arrington, Rachel; LeBlanc, Heidi; Spotted Elk, Davina; Dayzie, Irene; Rosenbrand, Reva

2008-01-01

71

Navajo Adult Basic Education.  

ERIC Educational Resources Information Center

The objectives of this Special Experimental Demonstration Project in Adult Basic Education for the Navajo were: (1) to raise the educational and social level of Navajo adult students who are unable to read, write, and speak English; (2) to assist the Navajo adult students to take advantage of occupational and vocational training programs; (3) to…

Navajo Community Coll., Tsaile, AZ.

72

Our Friends -- The Navajos.  

ERIC Educational Resources Information Center

Papers in this collection reflect the academic and on-reservation learning experiences of institute participants exposed to: Indian arts and crafts; the Navajo language; the Navajo people in their own homes, schools, and communities; basic knowledge of Indians; ceremonies, community meetings, and neighboring reservations; and major problems and…

Navajo Community Coll. Press, Tsaile, AZ.

73

NAVAJO ELECTRIFICATION DEMONSTRATION PROJECT  

SciTech Connect

The Navajo Electrification Demonstration Project (NEDP) is a multi-year project which addresses the electricity needs of the unserved and underserved Navajo Nation, the largest American Indian tribe in the United States. The program serves to cumulatively provide off-grid electricty for families living away from the electricty infrastructure, line extensions for unserved families living nearby (less than 1/2 mile away from) the electricity, and, under the current project called NEDP-4, the construction of a substation to increase the capacity and improve the quality of service into the central core region of the Navajo Nation.

Terry W. Battiest

2008-06-11

74

Provenance of Norphlet sandstone, northern Gulf Coast  

Microsoft Academic Search

The Upper Jurassic Norphlet sandstone of the northern Gulf Coast is predominantly subarkose, with some arkose in the eastern area and sublitharenite and quartzarenite in the western area. Despite great depths of burial and despite feldspar and rock-fragment constituents, diagenesis has not appreciably altered the composition of Norphlet sandstone. Therefore, reconstruction of original composition of Norphlet sandstone presented little difficulty.

W. P. Ryan; W. C. Ward; R. L. Kuglar

1987-01-01

75

Architectural studies of Jurassic-Cretaceous fluvial units, Colorado Plateau  

SciTech Connect

A sixfold hierarchy of architectural elements and bounding surfaces evolved from outcrop studies of three fluvial units: Westwater Canyon member (WCM), Morrison Formation, Upper Jurassic; Torrivio sandstone member (TSM), Gallup Sandstone, Upper Cretaceous, northwestern New Mexico; and Kayenta Formation (KF), Lower Jurassic, southwestern Colorado. This hierarchy is discussed.

Miall, A.D.; Bromley, M.H.; Cowan, E.J.; Turner-Peterson, C.E.

1989-03-01

76

Contemporary Navajo Affairs: Navajo History Volume III, Part B.  

ERIC Educational Resources Information Center

Written specifically for Navajo junior high through college students, but also serving those interested in modern reservation developments and processs, the third volume of a curricular series on Navajo history provides a synthesis of data and pictorial records on current events in the areas of Navajo government, economic development, and health.…

Eck, Norman K.

77

Navajo Reflections on Climate Change  

NSDL National Science Digital Library

In this video segment adapted from Navajo Technical College, meet two members of the Navajo Nation, one Elder and one scientist, as they share their observations about how precipitation has changed since they were children.

2012-03-16

78

Protection of Navajo Sacred Objects  

E-print Network

because it partly assisted in the initial establishments of pawnshops on Navajo lands. After the 1900s, the number of trading posts increased, as did the value of Indian made goods. Navajo crafts such as rugs and turquoise jewelry became very valuable.... 22 21 Caitlin O?Neil, ?Life on the Reservation,? The Navajo Yesterday and Today 7 Oct. 2003: 1 22 Leo W. Banks, ?Navajo Rugs,? Arizona Highways 2 Aug. 2004: 42-43. 32 Turquoise Squash...

Yazzie, Elerina

2008-07-31

79

NAVAJO NATION HAZARDOUS WASTE SITES  

EPA Science Inventory

This point coverage represents the locations of hazardous waste sites on the Navajo Nation Indian Reservation. The point locations were delineated on 1:24,000 scale US Geological Survey (USGS) topographic maps by staff from the Navajo Nation EPA, Resource Conservation & Reco...

80

Navajo Nation Educational Hearings, 1975.  

ERIC Educational Resources Information Center

Part of an effort by the Navajo Division of Education to formulate a comprehensive educational plan, this document includes testimony by people representing the five agency divisions on the Reservation (Shiprock, Crownpoint, Chinle, Tuba City, and Fort Defiance) and the public school districts serving Navajos. Also included is a synthesis of the…

Navajo Tribe, Window Rock, AZ.

81

To Be A Navajo. Second Edition, 1976.  

ERIC Educational Resources Information Center

Designed to provide culturally relevant and interesting reading material in Navajo for Navajo speaking children, this booklet presents 20 short stories written and illustrated by students at Rough Rock Demonstration School. Intended to encourage Navajo speaking children, and others, to read and to instill pride in being a Navajo, the stories…

Begay, Shirley M., Ed.

82

Navajo Coal: Demands, Attitudes, and Environment.  

ERIC Educational Resources Information Center

The operation of several coal mines with vast proven reserves on the Navajo reservation is a manifestation of conflict between: a power hungry external world; the preservationist attitudes of traditional Navajo culture; the disadvantaged socio-economic status of the average Navajo wage earner; and the Navajo Nation's long term needs for internal…

Goodman, James M.

83

A History of Navajo Clans. First Edition.  

ERIC Educational Resources Information Center

Pen and ink drawings illustrate characterizations of 29 Navajo clans in this book, which is intended to acquaint young Navajo people and others with Navajo history and culture. The introduction discusses the significance of the Navajo clan system and the relationship among family bonds, self-esteem, and cultural values. The illustrated text tells…

Lynch, Regina H.; And Others

84

Hydrogeology of the Mercosul aquifer system in the Paraná and Chaco-Paraná Basins, South America, and comparison with the Navajo-Nugget aquifer system, USA  

NASA Astrophysics Data System (ADS)

The giant Mercosul aquifer system consists of Triassic-Jurassic eolian-fluvio-lacustrine sandstones confined by Cretaceous basalt flows, and it covers about 1,195,500 km2 (461,583 miles2) in South America. The aquifer system encompasses all of the Paraná Basin and part of the Chaco-Paraná Basin and is one of the world's largest. The eolian Botucatu Sandstone and its equivalents form an important part of this system. Maps of structure, thickness of overlying rocks, and water temperature, and a potentiometric map, all based on 322 wells, define hydrogeologic characteristics and provide the basis for establishing guidelines for the long-term equilibrium use of this important multinational aquifer system. The Mercosul aquifer system is divided into two domains - the larger and better understood Paraná Basin and the smaller and less well understood Chaco-Paraná Basin. Most of the northern part of the Paraná Basin has axially-directed groundwater flow, whereas the southern part of the aquifer discharges mostly to the southwest into the Corrientes Province of Argentina, with negligible discharge into the Atlantic Ocean. The Mercosul aquifer system is conservatively estimated to have been flushed at least 180 times since deposition. Various factors are responsible for this flushing, including appreciable rainfall since the end of the Cretaceous Period, probable uplift of the basins' borders in Late Cretaceous time, simple basin geometry, long-term riverine and groundwater flow to the southwest (ancestral and present Paraná River Systems), and stable cratonic setting. Key hydraulic properties of the Mercosul aquifer system are compared to those of the eolian Jurassic Navajo-Nugget System of the western United States. The results demonstrate the importance of tectonics and climate on the evolution of sub-continental aquifer systems.

Arújo, L. M.; França, A. B.; Potter, P. E.

1999-06-01

85

Navajo Rug with English Voice  

NSDL National Science Digital Library

This interactive Flash lesson helps students to distinguish squares and triangles and be creative in the context of Navajo rug design. The animated pages give printed and voiced instructions in English. A teacher guide (pdf) is available - see #30 at MathActive Lessons for Grades K-2, cataloged separately. Navajo, Spanish, and non-spoken versions of the lesson are available also at the Lessons page.

Jeneen Edgmon

2011-01-01

86

Navajo Pawn: A Misunderstood Traditional Trading Practice  

ERIC Educational Resources Information Center

Navajo trading has been a crucial component of that tribe's localized economy for generations and has been the subject of much scholarship over the years. The role of the Navajo trader in influencing the types and styles of crafts that Navajos created as well as providing tribal members with an outlet for those items remains important to their…

Kiser, William S.

2012-01-01

87

Compensation of Navajo Uranium Miners  

NSDL National Science Digital Library

This site addresses policy issues of the compensation of Navajo uranium miners. The site provides an annotated index of current issues, legislation, papers and presentations, books, and links that lead to more information on uranium miners. Imbedded links throughout the text lead to related information.

World Information Service on Energy Uranium Project

88

Memo to Navajo Community Schools.  

ERIC Educational Resources Information Center

This handbook contains general resource information for program planning in Navajo education. Contained are listings on: 1) Key Questions; 2) Community Education and Local Control; 3) Education Laboratories; 4) Steps in Starting A Community College; 5) Recommended Books; 6) Bibliography of Instructional Resources; 7) Program Planning and Proposal…

Lee, George P.

89

Navajos and National Nuclear Policy.  

ERIC Educational Resources Information Center

Describes the history of nuclear development in New Mexico, notes the cumulative detrimental effect on the Navajo Nation, and emphasizes federal inaction regarding health and safety standards and regulation in the nuclear power industry. Journal availability: see RC 503 522. (SB)

Barry, Tom

1979-01-01

90

Geologic and Navajo Time Line  

NSDL National Science Digital Library

This lab serves to introduce students to geologic time and serves as an outline for the course through the semester. Students use a tape register and must mark out the corresponding length of each Geologic Era and Eon towards the beginning of the course. Above Western time line Navajo students construct their own time line correlating events as best as possible. As the course progresses starting from 4.6bya each week they must draw major events that occur marking correct subdivisions of time and ages ago. As fossil life gets more complex such as beginning in the Paleozoic students are must take different categories of fossils or different periods so all are doing different things but working together. (Similarly the Navajo time line builds. This time line is taped around the room---and I would have liked to paint the two time lines along the corridor of the building but Maintenance axed it.

Margaret Mayer

91

Provenance of Norphlet sandstone, northern Gulf Coast  

SciTech Connect

The Upper Jurassic Norphlet sandstone of the northern Gulf Coast is predominantly subarkose, with some arkose in the eastern area and sublitharenite and quartzarenite in the western area. Despite great depths of burial and despite feldspar and rock-fragment constituents, diagenesis has not appreciably altered the composition of Norphlet sandstone. Therefore, reconstruction of original composition of Norphlet sandstone presented little difficulty. Variation in detrital modes of the Norphlet suggests compositionally distinct source terranes. Samples from Florida, Alabama, and Mississippi reflect the influence of metamorphic and plutonic rocks of the Appalachian Piedmont Province and of Triassic-Jurassic volcanic rocks. Sandstones in east Texas, northern Louisiana, and southern Arkansas were derived from sedimentary and metasedimentary rocks of the Ouachita system. The Arbuckle Mountains and Llano uplift may have supplied trace amounts of quartzo-feldspathic and volcanic-rock fragments to the extreme western part of the study area. Norphlet sandstones represent a mixture of collision-orogen-derived sediment from the Appalachian and/or Ouachita system and continental-block-derived sediment from paleohighs and uplifts within the Gulf basin. However, Norphlet sandstones plot in the craton-interior and transitional-continental fields on Q-F-L and QM-F-Lt tectonic-provenance diagrams, because of mineralogically mature source rocks, elimination of unstable grains by abrasion and sorting during deposition, and/or sediment mixing from different source terranes.

Ryan, W.P.; Ward, W.C.; Kuglar, R.L.

1987-09-01

92

Sandstone Quarry  

USGS Multimedia Gallery

A view of the Sandstone Quarry in Red Rock Canyon. Red Rock Canyon is a National Conservation Area managed by the Bureau of Land Management, located just outside of Las Vegas, Nevada. It is part of the Mojave Desert....

93

Working with Navajo Parents of Exceptional Children.  

ERIC Educational Resources Information Center

Undergraduate students at Northern Arizona University interviewed and surveyed 20 staff members at Kayenta Unified School District (KUSD) on the Navajo Reservation and 14 parents of exceptional Navajo children enrolled in KUSD. Both groups were asked to identify challenges affecting the working relationship between parents and school on a rural…

Jones, Doris; And Others

94

"1970" Inter-Agency Health Meeting (Navajo).  

ERIC Educational Resources Information Center

An inter-agency health meeting regarding health services for Navajo Indians is reported on in this document. The meeting, sponsored by the Arizona Commission of Indian Affairs, involved agencies such as the U.S. Public Health Service, Bureau of Indian Affairs, and the Navajo Tribe. Included in the proceedings are reports and remarks by…

Arizona Commission of Indian Affairs, Phoenix.

95

Navajo Health Authority: Accomplishments--Future Goals.  

ERIC Educational Resources Information Center

Accomplishments of the Navajo Health Authority (NHA) since it began in 1972 are presented in synopsis form in a report of programs underway at Window Rock and Shiprock, along with NHA goals: to promote development of Navajo Health manpower, preventive medicine, health education, and native healing sciences. After a brief review of executive and…

Navajo Health Authority, Window Rock, AZ.

96

Navajo generating plant and Grand Canyon haze  

SciTech Connect

This article examines the question of whether the Navajo generating plant pollution is contributing to pollution of the air in the Grand Canyon region. The topics include the regulatory context of the plant, the experiment known as the Winter Haze Intensive Tracer Experiment (WHITEX), the National Research Council evaluation of the WHITEX, and The Navajo Generating Station Visibility Study.

Norris, J.E.

1991-01-15

97

A Jurassic Shock-Aftershock Earthquake Sequence Recorded by Small Clastic Pipes and Dikes within Dune Cross-Strata, Zion National Park, Utah  

NASA Astrophysics Data System (ADS)

Eolian sandstones of south-central and southeast Utah contain large volumes of contorted cross-strata that have long been recognized as products of liquefaction caused by seismic shaking. Unlike most sites where Navajo Sandstone is exposed, in Zion National Park (southwestern Utah), the Navajo contains very, very few contorted strata. We have, however, mapped the distribution of more than 1,000 small-scale, vertical pipes and dikes in uncontorted cross-strata of the Navajo at two small study sites in Zion. Pipes are 2-5 cm in diameter and up to 3 m long; dikes are ~6 cm wide. Clusters of the water-escape structures lie directly above and below numerous, near-horizontal bounding surfaces. Dikes are restricted to the wind-ripple strata that lie above the bounding surfaces. Pipes are common both above and below the bounding surfaces. In map view, most pipes are arranged in lines. Near the bounding surfaces, pipes merge upward with shallow dikes trending parallel to the lines of pipes. Pipes formed in grainflows—homogeneous, well-sorted sand lacking cohesion. Dikes formed above the bounding surface, in more-cohesive, poorly sorted, wind-ripple strata. As liquefaction began, expansion of subsurface sand caused spreading within the unliquified (capping) beds near the land surface. Dikes intruded cracks in the wind-ripple strata, and pipes rose from the better-sorted sand to interdune surfaces, following trends of cracks. Because the wind-ripple strata had low cohesive strength, a depression formed around each rupture, and ejected sand built upward to a flat-topped surface rather than forming the cone of a classic sand volcano. In one 3 m2 portion of the map area, a cluster of about 20 pipes and dikes, many with truncated tops, record eight stratigraphically distinct seismic events. The large dunes that deposited the Navajo cross-strata likely moved ~1m/yr. When, in response to seismic shaking, a few liters of fluidized sand erupted onto the lowermost portion of the dune lee slope through a pipe, the erupted sand dried and was buried by climbing wind-ripple strata as the large dune continued to advance downwind. The mapped cluster recording eight distinct seismic events lies within thin-laminated sediment that was deposited by wind ripples during 1 m (~ 1 year) of southeastward dune migration. We conclude that the small pipes and dikes of our study sites are products of numerous >MM 5 earthquakes, some of which recurred at intervals of less than 2 months. We interpret one small cluster of pipes and dikes with well-defined upward terminations as a distinct shock-aftershock sequence. Because the largest modern earthquakes can produce surface liquefaction only up to about 175 km from their epicenters, the Jurassic epicenters must have been well within that distance. The tendency of modern plate boundaries to produce high-frequency aftershocks suggests that the epicenter for this Jurassic sequence lay to the southwest, within the plate boundary zone (not within continental rocks to the east). As eolian dunes steadily migrate over interdune surfaces underlain by water-saturated dune cross-strata, the thin, distinct laminae produced by the wind ripples that occupy dune toes can faithfully record high-frequency seismic events.

Loope, D. B.; Zlotnik, V. A.; Kettler, R. M.; Pederson, D. T.

2012-12-01

98

Soil genesis of mine spoil, Navajo Mine, New Mexico  

SciTech Connect

Documenting mine spoil genesis has been limited in the Western States. Few areas have {open_quotes}before{close_quotes} and {open_quotes}after{close_quotes} type data and for some mines older reclamation areas are limited. Soil samples were collected from 8-11 year old reclaimed spoil as part of a rooting depth study completed in June 1987 at the Navajo Mine. Samples were collected in 25 cm increments to depths of at least 200 cm and most often to 350 cm at a total of fifteen different reclamation plots. The spoil was composed of various amounts of shale and sandstone. The sites represented different topographic positions (swale/backslope), reclamation ages (8 to 11 years), slopes (0-15%), and topdressing treatments (with and without).

Buchanan, B.A. [New Mexico State Univ., Las Cruces, NM (United States); Stutz, H.C. [Brigham Young Univ., Provo, UT (United States); Estrada, O.J. [BHP - Utah International Inc., Fruitland, NM (United States)

1990-12-31

99

Traditional versus Contemporary Navajo Views of Special Education.  

ERIC Educational Resources Information Center

A survey and interviews examined the beliefs of traditional and contemporary Navajos concerning individuals with disabilities. Participants were 30 staff members from the Kayenta and Pinon Unified School Districts (Arizona), of whom 21 were Navajos, 8 Anglos, and 1 Hispanic; 1 Anglo and 8 Navajo community professionals; and 15 Navajo parents,…

Medina, Catherine; Jones, Doris; Miller, Susan

100

Diné (Navajo) Ethno- and Archaeoastronomy  

NASA Astrophysics Data System (ADS)

The Navajo (Diné) are an Athabascan-speaking people who migrated from the far northwest of America into the desert southwest where they became the largest surviving Native American culture. Three words portray Diné philosophy - beauty, harmony, and balance. Their traditions are rich with astronomical symbolism found in literature, ceremony, iconography, artifacts, rock art, and the sacred landscape. This chapter summarizes Diné astronomical traditions, identification of stars known to be important to the Diné, and how these are depicted on artifacts and rock art.

Chamberlain, Von Del

101

Final Report - Navajo Electrification Demonstration Project - FY2004  

SciTech Connect

The Navajo Electrification Demonstration Project (NEDP) is a multi-year projects which addresses the needs of unserved Navajo Nation residents without basic electricity services. The Navajo Nation is the United States' largest tribe, in terms of population and land. An estimated 18,000 Navajo Nation homes do not have basic grid-tied electricity--and this third year of funding, known as NEDP-3, provided 351 power line extensions to Navajo families.

Kenneth L. Craig, Interim General Manager

2007-03-31

102

Jurassic petroleum trends in eastern Gulf Coastal Plain and central and eastern Gulf of Mexico  

SciTech Connect

Three Jurassic petroleum trends can be delineated in Mississippi, Alabama, and Florida, and in the central and eastern Gulf of Mexico. These trends are recognized by characteristic petroleum traps, reservoirs, and hydrocarbon types. The source for the Jurassic hydrocarbons is Smackover algal mudstones. The Jurassic oil trend includes the area north of the regional peripheral fault systems in the tri-state area, and extends into the area north of the Destin anticline. Traps are basement highs and salt anticlines, with Smackover grainstones and dolostones and Norphlet marine, eolian, and wadi sandstones as reservoirs. This trend has potential for Jurassic oil accumulations in the eastern Gulf of Mexico. The Jurassic oil and gas-condensate trend includes the onshore area between the regional peripheral fault systems and Wiggins arch and extends into the area of the Destin anticline. Traps are basement highs, salt related anticlines, and extensional faults. Cotton Valley fluvial-deltaic sandstones, Haynesville carbonates and fluvial-deltaic sandstones, Smackover grainstones, packstones, dolostones, and marine sandstones, and Norphlet marine, eolian, and wadi sandstones serve as reservoirs. This trend contains most of the Jurassic fields in the eastern Gulf coastal plain. The trend has high potential for significant petroleum accumulations in the eastern Gulf of Mexico. The Jurassic deep natural gas trend includes the onshore area south of the Wiggins arch and extends into the Mississippi-Alabama shelf. Traps are faulted salt anticlines with basement highs as potential traps. Cotton Valley deltaic-strandplain sandstones and Norphlet eolian sandstones are the reservoirs. Several gas discoveries below 20,000 ft have been made in this trend in Mississippi and offshore Alabama. The trend has excellent potential for major gas accumulations in coastal Alabama and central Gulf of Mexico.

Mancini, E.A.; Mink, R.M.; Bearden, B.L.

1986-05-01

103

Sandstone Cliffs  

USGS Multimedia Gallery

Views along the Queen's Garden Trail in Bryce Canyon National Park. Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolomite that caps them and the sands...

104

Dual Language = Saad Ahaah Sinil. A Navajo-English Dictionary. Revised Edition.  

ERIC Educational Resources Information Center

A dual-language Navajo-English dictionary provides a chart of the Navajo kinship system, a two-page map of the Navajo Nation, and English equivalents for Navajo words in 46 linguistic and cultural categories. Included are words for: races (Indian and other ethnic groups); Navajo clans; age groups; Navajo ceremonies; body parts; sickness; clothing;…

Austin, Martha, Ed.; Lynch, Regina, Ed.

105

The Navajo Uranium Mining Experience, 2003-1952  

NSDL National Science Digital Library

This bibliography, compiled by the Southwest Research and Information Center, contains resources related to Navajo uranium issues and communities affected by uranium mining impacts since the mid-1970s. Entries were selected for their relevancy to Navajo community concerns, Navajo Nation policies, and health and environmental effects of uranium development on Navajo lands. Topics for resources include articles, books, policy statements, reports, presentations, testimony, and published medical, scientific and sociological literature.

Chris Shuey

106

Heterogeneity of eolian sandstones and enhanced oil recovery  

SciTech Connect

Eolian sandstones constitute a heterogeneous group of hydrocarbon reservoirs because of significant variations in sedimentology, diagenesis, and structural setting. Simple eolian reservoirs are associated with stratigraphic traps and generally produce from eolian-dune sandstones with preserved topographic relief. The main forms of heterogeneity in simple reservoirs are the stacking of stratification types (ripple, sandflow, and grainfall strata) and diagenetic variations within the eolian-dune sandstone. Simple reservoirs pose little difficulty to secondary and tertiary recovery technologies, provided directional permeabilities and fluid-flow pathways are known from careful analysis of core, dipmeter data, porosity logs, and, if possible, outcrop studies. Examples of simple eolian reservoirs are the Permian upper part of the Minnelusa Formation, Powder River basin, Wyoming, and the Jurassic Entrada Sandstone, San Juan basin, New Mexico. Complex eolian reservoirs are generally associated with structural traps where productive eolian-dune sandstones are intercalated with nonproductive sabkha, sand-sheet, or fluvial deposits, resulting in strongly layered reservoir behavior with respect to fluid flow and difficulties for EOR application. Heterogeneity in complex reservoirs is also caused by stratification types, diagenesis, and fractures in some reservoirs. Examples of complex eolian reservoirs include the Pennsylvanian-Permian Tensleep and Weber Sandstones of Wyoming and Colorado and the Jurassic Nugget Sandstone of Utah and Wyoming.

Schenk, C.J.; Krystinik, L.F. (Geological Survey, Denver, CO (USA))

1989-09-01

107

Health Problems of the Navajo Area and Suggested Interventions.  

ERIC Educational Resources Information Center

Analysis of morbidity, mortality, and demographic data on Navajo people was undertaken to identify leading health problems in the Navajo area and to suggest intervention activities. Comparisons with total U.S. population were made to provide perspective. Data on Navajo mortality showed: a ratio of male to female deaths of 2:1, more than 50 percent…

Kaltenbach, Charles

108

Navajo Health Authority, Board of Commissioners, Annual Report, June 1975.  

ERIC Educational Resources Information Center

The Navajo Health Authority (NHA) was created by the Navajo Tribal Council to guide and assist the Navajo people to improve their health and well-being. Its goals are to: (1) develop health manpower training programs appropriate to support the development of the American Indian Medical School and to meet the needs of the American Indians in…

Atcitty, Thomas E.

109

Navajo Adult Basic Education: Final Report 1971-1972.  

ERIC Educational Resources Information Center

The thrust of the Navajo Adult Basic Education (NABE) program is aimed at three major objectives. First, it seeks to establish, through the study of history and current events, a feeling of pride in Navajo cultural heritage, promoting self-esteem and building self-confidence. Next, it prepares the Navajo to function better in those areas of the…

Navajo Community Coll., Tsaile, AZ.

110

Petrophysical Properties of Sandstones Containing Deformation Bands Versus Those With Fractures: the Importance of Grain Contact Strength to Fault-Zone Structure  

NASA Astrophysics Data System (ADS)

In upper crustal fault zones, the majority of slip accumulates within a fault core, which is surrounded by a less deformed damage zone. Both the width and structural character of the damage zone affect its mechanical and hydrologic properties. Fault-related deformation can change rock mechanical properties, causing stress orientations to rotate in fault damage zones, and affecting seismicity over time. In addition, the types, densities, and orientations of structures in fault zones exert a first-order control on fault-zone permeability structure, permeability anisotropy, and flow pathways. For example, open-fracture damage zones enhance fault-parallel flow, whereas cataclastic deformation band networks slow flow in every direction except parallel to the line of intersection between bands. To improve our understanding of controls on damage zone character, we explored relationships between fault-zone structure and lithologic characteristics such as porosity and cement mineralogy in faulted quartz-rich sandstones. The sandstones chosen from fault sites in the Jurassic Navajo and Entrada sandstones in Utah, and the Cretaceous Mesaverde sandstone in Wyoming, exhibit a wide range in porosity. Samples collected include even greater variability in cements, from clay coatings on grains to patchy carbonate cement to grain-bridging quartz overgrowths and iron oxide cements. These variables demonstrably influence damage zone character, resulting in fractures in some locations and deformation bands in others (even within a single fault zone) and affecting deformation-band damage zone width. They likely influenced grain-contact strength also. Because ultrasonic velocity and related elastic moduli also vary with grain-contact strength, we measured P and S wave velocities as a function of confining pressure to 20 MPa as a sensitive proxy for grain-contact strength. More than 40 samples, including both host rock and rock with deformation bands, have been analyzed. Samples containing deformation bands display different ultrasonic velocities than adjacent samples lacking deformation bands. These data are used to evaluate the relative importance of the variables affecting deformation in clastic rocks. Establishing a quantitative link between fault structures, cements, porosity, and lithology and ultrasonic velocity will ultimately allow results to be directly applied to borehole geophysics and seismic reflection studies to improve prediction of fault-zone characteristics and fluid flow properties in quartz-rich sandstone reservoirs.

Schneider, J. R.; Tobin, H. J.; Goodwin, L. B.

2010-12-01

111

Kemik sandstone: inner shelf sand from northeast Alaska  

SciTech Connect

The upper Neocomian Kemik Sandstone crops out in and around Ignek Valley in northeast Alaska. It lies unconformably on the Jurassic to Lower Cretaceous Kingak Shale, and is overlain by the Hauterivian to Barremian Pebble shale. It is a fine-grained, glauconitic quartzose sandstone, up to 120 ft thick. Four lithofacies are recognized: (1) a basal, moderately well-sorted pebble conglomerate; (2) fine to very fine-grained, laminated and bioturbated sandstones; (3) a poorly sorted conglomerate; and (4) low-angle to hummocky cross-stratified fine-grained sandstones. Facies relationships suggest that the basal conglomerate represents a transgressive lag deposit. It is overlain by a sequence comprising laminated and bioturbated sandstones with interbedded, poorly sorted conglomerates. The sandstones exhibit a mixed assemblage of ichnofossils, including Gyrochorte, Muensteria, Ophiomorpha, Planolites, and Skolithos, and (.)Conichnus. In places, they grade upward from low-angle laminations to symmetrical ripple forms to silty laminated deposits. Their upper parts are bioturbated, but to varying extent. these sandstones and the conglomerates were deposited abruptly but sporadically below storm wave base by storm-generated currents. The sandstones were subsequently modified by strong but waning oscillating storm waves. The hummocky cross-stratified sediment comprises an upper sequence that was probably deposited under the influence of storm-induced conditions between fair-weather and storm wave base. The Kemik Sandstone represents a storm-deposited inner shelf sand with regressive characteristics, deposited within an overall transgressive setting.

Melvin, J.

1986-05-01

112

Internally-sourced quartz cement due to externally-derived CO 2 in sub-arkosic sandstones, North Sea  

Microsoft Academic Search

The Upper Jurassic sub-arkosic turbidite sandstones of the Magnus oil field, UK North Sea, are dominated by quartz, ankerite and kaolinite cements that all grew immediately prior to, and during, the early stages of oil-filling. The sandstones have no evidence of siliceous bioclasts or pressure dissolution yet contain ?15% quartz cement with relatively more in the water leg than in

R. H. Worden; S. A. Barclay

2000-01-01

113

Language Learning in the American Southwestern Borderlands: Navajo Speakers and Their Transition to Academic English Literacy.  

ERIC Educational Resources Information Center

The Navajo Nation wants a 2-year Navajo language requirement for regional colleges. At the same time, literacy in academic English is required for Navajo students wishing to enter the sciences, medicine, and law. The difficulties students face as they make the transition from English to Navajo and from Navajo to English are described. Four…

Dyc, Gloria

2002-01-01

114

Navajo Participation in Labor Unions. Lake Powell Research Project Bulletin Number 15, December 1975.  

ERIC Educational Resources Information Center

Navajo participation in labor unions and Navajo labor relations have undergone rapid and fundamental changes since the development of industry around Lake Powell and on Black Mesa. Early attempts to unionize Navajo workers met with stiff resistance from employees and the Navajo Tribal Council. Union entry into the Navajo Reservation was viewed as…

Robbins, Lynn A.

115

Jurassic Park Safety Audit  

NSDL National Science Digital Library

Using the first 30 minutes of the film Jurassic Park, the student will audit it for violations of safety rules and regulations, OSHA violations, and violations of HASP's. Access to the activity required free and quick registration with ATEEC.

116

Jurassic Reef Park  

NSDL National Science Digital Library

This is a bilingual, educational website from Munich, Germany. The main feature is a virtual field trip to the reefs of the Jurassic period. Besides a view of the Jurassic reefs, their builders, and their ecological settings, there is also an emphasis on the importance of modern reefs as indicators of the state-of-health of the globe and evidence of how some changes in the composition of reefs may represent the forerunners of catastrophic, regional or global, environmental change.

Reinhold Leinfelder

117

Jurassic Reef Park  

NSDL National Science Digital Library

Dr. Reinhold Leinfelder of the University of Stuttgart, Germany created this interesting site in English and German, offering a "virtual trip to the reefs of the Jurassic Period." In the Introduction, viewers will find background material and comparisons of modern and ancient reefs. Further information is provided in the sections on reef architecture, reef formation, Jurassic reefs, and reefs and global climate change. Although the English language is slightly quirky, the content and images more than compensate, making this a worthwhile site.

118

Ichnology of Lower Jurassic beach deposits in the Shemshak Formation at Shahmirzad, southeastern Alborz Mountains, Iran  

Microsoft Academic Search

A 19 m thick package of well-sorted lowermost Jurassic (Hettangian-Lower Sinemurian?) sandstones within the Shemshak Formation\\u000a of the southeastern Alborz Mountains displays features characteristic of foreshore to upper shoreface environments such as\\u000a tabular bedding, low-angle lamination, trough cross-stratification, parting lineation, and oscillation ripples. In contrast\\u000a to most other beach successions recorded in the literature the sandstones contain a trace fossil assemblage

Franz T. Fürsich; Markus Wilmsen; Kazem Seyed-Emami

2006-01-01

119

Navajo Language and Culture in Adult Education.  

ERIC Educational Resources Information Center

Examples of culturally relevant education for Navajo adults are described: (1) Arizona State Prison Literacy Program; (2) Dine College Teacher Preservice Program; (3) Salt Lake City East Community School; and (4) Family and Child Education Program. The examples attest to the power of native language literacy. (SK)

Lockard, Louise

1999-01-01

120

The Hawaii-Navajo Exchange Program.  

ERIC Educational Resources Information Center

The 1969-70 Leeward Cultural Exchange program described in this report involved a 2-week exchange between 20 grade-5 students of Leeward Oahu, Hawaii, and 24 grade-5 students from the Toyei Boarding School on the Navajo Indian Reservation in northern Arizona. In the report, the program objectives are listed along with a statement of organizational…

Brewer, Kenneth, Comp.; And Others

121

Navajo Bibliography with Subject Index. Revised Edition.  

ERIC Educational Resources Information Center

Approximately 5,640 references oriented to the Navajo people, their land, and environment compose this revised bibliography. The references--published between 1638 and 1971--include historical, enthnographic, biographic, technical, popular, and fictional works as well as archival and congressional materials, newspaper accounts, articles from…

Correll, J. Lee; And Others

122

78 FR 16825 - Approval of Air Quality Implementation Plans; Navajo Nation; Regional Haze Requirements for...  

Federal Register 2010, 2011, 2012, 2013, 2014

...Haze Requirements for Navajo Generating Station; Extension of Comment Period AGENCY...FIP) requiring the Navajo Generating Station (NGS), located on the Navajo Nation...available only at EPA Region 9 (e.g., maps, voluminous reports, copyrighted...

2013-03-19

123

78 FR 58987 - Approval of Air Quality Implementation Plans; Navajo Nation; Regional Haze Requirements for...  

Federal Register 2010, 2011, 2012, 2013, 2014

...Requirements for Navajo Generating Station; Extension of Public Comment...for the Navajo Generating Station (NGS), located on the...at EPA Region 9 (e.g., maps, voluminous reports, copyrighted...Related to Navajo Generating Station (NGS)'' dated July...

2013-09-25

124

Diagenesis of fluvial sands in Norphlet Formation (Upper Jurassic), Escambia County, Alabama  

Microsoft Academic Search

The Upper Jurassic Norphlet Formation is an important hydrocarbon reservoir in Baldwin and Mobile Counties and offshore in Mobile Bay, Alabama. The formation is not productive in the Little Escambia Creek field, Escambia County, but underlies the productive Smackover Formation at a depth of approximately 15,500 ft (4725 m). The Norphlet sandstones examined in cores from two drill holes are

C. W. Keighin; C. J. Schenk

1989-01-01

125

Haynesville sandstone reservoirs in the Updip Jurassic trend of Alabama  

Microsoft Academic Search

Subsequent to the 1986 drilling of the 1 Carolyn McCollough Unit 1-13 well, which initiated production from the Frisco City sand of the Haynesville Formation in Monroe County, Alabama, seven Haynesville fields have been established in Covington, Escambia, and Monroe counties. Initial flow rates of several hundred BOPD are typical for wells in these fields, and maximum rates exceed 2000

R. L. Kugler; R. M. Mink

1994-01-01

126

Incidence and prevalence of Parkinson's disease among Navajo people living in the Navajo nation.  

PubMed

Parkinson's disease (PD) is largely unstudied among American Indians. Unique populations might harbor clues to elusive causes. We describe the incidence and prevalence of PD among Navajo people residing in the Navajo Nation, home to the largest American Indian tribe in the United States. We analyzed 2001-2011 inpatient and outpatient visit data for Navajo people obtained from the Indian Health Service, which provides health care to American Indian people living on the Navajo Reservation. Cases were defined by at least two inpatient or outpatient visits with the diagnosis of PD. Crude and age-adjusted incidence and prevalence rates were calculated overall as well as by age, sex, region of residence, and time period. Five hundred twenty-four Navajo people with median age-at-onset of 74.0 years were diagnosed with PD during the study period, yielding an average annual crude incidence rate of 22.5/100,000. Age-specific incidence was 232.0 for patients 65 years of age or older and 302.0 for 80 years of age or older. Age-adjusted incidence was 35.9 overall (238.1 for ?65 years), was higher in men than in women (47.5 vs. 27.7; P?Navajo People appears to be as high as or higher than rates reported in many other populations. Rates increased to the highest age group, consistent with population-based studies. Further investigation is warranted to examine risk factors for PD in this remote population. © 2015 International Parkinson and Movement Disorder Society. PMID:25649219

Gordon, Paul H; Mehal, Jason M; Holman, Robert C; Bartholomew, Michael L; Cheek, James E; Rowland, Andrew S

2015-04-15

127

Exploring Jurassic Park.  

ERIC Educational Resources Information Center

Describes several student-tested activities built around "Jurassic Park." The activities feature students engaged in role-playing scenarios, investigative research projects, journal writing and communications skills activities, cooperative learning groups, and learning experiences that make use of reading skills and mathematical knowledge. (PR)

Simmons, Patricia E.; Wiley, Clyde

1993-01-01

128

Microstructural analysis of quartz grains in Vasyugan suite sandstones of layer Ui1-21 in Kazanskoe deposit  

NASA Astrophysics Data System (ADS)

Microstructural analysis of quartz grains in sandstones revealed preferred directions which define and influence porosity and permeability anisotropy in oil and gas reservoirs In this research, we investigated the Upper Jurassic sandstone reservoir sediments from 14 wells in Kazanskoe field. The authors studied: the orientation of elongated quartz grains, and intergranular fracture within grains, as well as the pore space in oriented thin sections of sandstones. The analysis of elongated quartz grains in the bedding plane showed three main types of preferred directions in quartz grain orientation along different axes in sandstone reservoirs. Obtained results allow identifying a variability of facies and dynamic depositional environment for Upper Jurassic sandstone formation. Subsequently, these results can be used in field modeling, as well as pattern optimization of injection and production wells.

Cherdantseva, D.; Krasnoshchekova, L.

2014-08-01

129

Navajo Uranium Education Programs: The Search for Environmental Justice  

ERIC Educational Resources Information Center

Uranium mining and milling in the Four Corners' area of the American Southwest has had serious negative impacts on American Indian workers, their families, and their communities. In this article, we will examine Navajo education programs which inform citizens about risks and health impacts associated with radiation exposures. Because the Navajo

Charley, Perry H.; Dawson, Susan E.; Madsen, Gary E.; Spykerman, Bryan R.

2004-01-01

130

Mask of Black God: The Pleiades in Navajo Cosmology  

NSDL National Science Digital Library

One Navajo legend attributes the creation of the primary stars and constellations to Black God. Today, a famous star cluster--the Pleiades--often appears on the traditional mask worn by chanters impersonating Black God during special ceremonies. In this case study, students learn about the Pleiades in Navajo cosmology while honing their observational and star map skills.

Teresa M. Schulz

2005-10-01

131

Mask of Black God: The Pleiades in Navajo Cosmology  

ERIC Educational Resources Information Center

One Navajo legend attributes the creation of the primary stars and constellations to Black God. Today, a famous star cluster--the Pleiades--often appears on the traditional mask worn by chanters impersonating Black God during special ceremonies. In this case study, students learn about the Pleiades in Navajo cosmology while honing their…

Schulz, Teresa M.

2005-01-01

132

The Navajo Agricultural Projects Industry: Subsistence Farming to Corporate Agribusiness.  

ERIC Educational Resources Information Center

Originally designed to create small farms for individual Navajos, the irrigation project has grown into a single 110,000-acre corporate agribusiness, the land's management has fallen out of the grasp of individual Navajos, and the idea of subsistence farming has been plowed under for the planting of major money-making crops. (NQ)

Barry, Tom

1979-01-01

133

Navajo Area Health and Physical Education Curriculum Guidelines.  

ERIC Educational Resources Information Center

Based on health education needs of Navajo children as established by the Navajo Area health and physical education committees, this curriculum guideline for health and physical education is delineated into three phases reflecting emphasis of instructional techniques (introductory, exploration/extended learning, widened learning) and three levels…

Tomah, Kent; And Others

134

"Dine Bikeya": Teaching about Navajo Citizenship and Sovereignty  

ERIC Educational Resources Information Center

The Navajo Nation, comprising the largest land area allocated mainly to a Native American jurisdiction in the United States, offers a unique opportunity to enhance students' understandings of citizenship rights and sovereignty. For example, what does sovereignty mean on the reservation? What is the relationship between the Navajo Nation and the…

Washington, Elizabeth Yeager; van Hover, Stephanie

2011-01-01

135

Bilingual Teaching in Content Areas: Navajo/English.  

ERIC Educational Resources Information Center

A Navajo/English bilingual program uses the student's knowledge of his first language, offers the opportunity to speak in two languages, and helps the student move from the home experience to the school experience. It gives instruction in content materials to all students either in English or in Navajo and direct language instruction in both…

Carrillo, F. M.; Carrillo, Ida S.

136

Navajo Archaeologist Is Not an Oxymoron: A Tribal Archaeologist's Experience  

ERIC Educational Resources Information Center

Many Navajos, or Dines, and Native American people in general, are archaeologists or are becoming archaeologists. The distinction between "Native Americans" and "archaeologists" in academia, or elsewhere, is no longer accurate. This fact should not come as such a surprise. As the epigraph, a quote by Richard Begay, demonstrates, Navajo people, for…

Two Bears, Davina R.

2006-01-01

137

Nursing Care and Beliefs of Expectant Navajo Women (Part 1).  

ERIC Educational Resources Information Center

Provides cultural background relevant for the delivery of health services to expectant Navajo women and their offspring including morbidity/mortality rates and trends and prevalent health problems. Reports results of a questionnaire administered to 479 expectant Navajo women and used to identify cultural practices distinguishing among traditional,…

Milligan, B. Carol

1984-01-01

138

Laughter: The Navajo Way. Humorous Stories of the People (in Navajo and English) Volume One.  

ERIC Educational Resources Information Center

This book has been prepared for the use of teachers, ethnologists, linguists, Indian studies scholars, language students and those who have an interest in the languages and cultures of the earlier inhabitants of this continent. The stories reflect the Navajo love for and genius with words and humor. Most of the humor represented is of three basic…

Wilson, Alan; Dennison, Gene

139

A Survey of Library Services Available to Navajo People on the Navajo Indian Reservation.  

ERIC Educational Resources Information Center

While the need for library services on the Navajo Reservation in Arizona is great, financial support is at the legal minimum, which is inadequate. A reason for this is that Indians on reservations pay no state income tax, and are therefore not entitled to state support, but must rely on federal funding. A model for a possible solution to this…

Wood, Margaret

140

Dine bikeyah bik'ah (Navajo oil): An ethnohistory, 1922-1960  

Microsoft Academic Search

Oil was discovered on the Navajo reservation in 1922, and as a result, the U.S. Department of the Interior pressured Navajos into leasing their lands to develop it. This study reveals that, at first, government officials hoped Navajos would quietly acquiesce, but instead Navajos fought for control. Moreover, oil development served as a basis for tribal debates over such issues

Kathleen Patricia Chamberlain

1998-01-01

141

Chapter 2. Assessment of undiscovered conventional oil and gas resources--Upper Jurassic-Lower Cretaceous Cotton Valley group, Jurassic Smackover interior salt basins total petroleum system, in the East Texas basin and Louisiana-Mississippi salt basins provinces.  

USGS Publications Warehouse

The Jurassic Smackover Interior Salt Basins Total Petroleum System is defined for this assessment to include (1) Upper Jurassic Smackover Formation carbonates and calcareous shales and (2) Upper Jurassic and Lower Cretaceous Cotton Valley Group organic-rich shales. The Jurassic Smackover Interior Salt Basins Total Petroleum System includes four conventional Cotton Valley assessment units: Cotton Valley Blanket Sandstone Gas (AU 50490201), Cotton Valley Massive Sandstone Gas (AU 50490202), Cotton Valley Updip Oil and Gas (AU 50490203), and Cotton Valley Hypothetical Updip Oil (AU 50490204). Together, these four assessment units are estimated to contain a mean undiscovered conventional resource of 29.81 million barrels of oil, 605.03 billion cubic feet of gas, and 19.00 million barrels of natural gas liquids. The Cotton Valley Group represents the first major influx of clastic sediment into the ancestral Gulf of Mexico. Major depocenters were located in south-central Mississippi, along the Louisiana-Mississippi border, and in northeast Texas. Reservoir properties and production characteristics were used to identify two Cotton Valley Group sandstone trends across northern Louisiana and east Texas: a high-permeability blanket-sandstone trend and a downdip, low-permeability massive-sandstone trend. Pressure gradients throughout most of both trends are normal, which is characteristic of conventional rather than continuous basin-center gas accumulations. Indications that accumulations in this trend are conventional rather than continuous include (1) gas-water contacts in at least seven fields across the blanket-sandstone trend, (2) relatively high reservoir permeabilities, and (3) high gas-production rates without fracture stimulation. Permeability is sufficiently low in the massive-sandstone trend that gas-water transition zones are vertically extensive and gas-water contacts are poorly defined. The interpreted presence of gas-water contacts within the Cotton Valley massive-sandstone trend, however, suggests that accumulations in this trend are also conventional.

Dyman, T.S.; Condon, S.M.

2006-01-01

142

Area Health Education Center of the Navajo Health Authority to Establish the Navajo Center for Health Professions Education.  

ERIC Educational Resources Information Center

The Area Health Education Center (AHEC) is designed to provide educational opportunities in health and allied fields and to improve health care for the Navajo people and other Indians in the region that includes and immediately surrounds the Navajo Indian Reservation. As prime contractor, the University of New Meixco School of Medicine will…

Navajo Health Authority, Window Rock, AZ.

143

Looking after the Land: The Navajo Dryland Environments Laboratory Researches the Environmental Needs of the Navajo Nation.  

ERIC Educational Resources Information Center

Describes the formation and operations of the Navajo Dryland Environments Laboratory (NDEL). NDEL, established by the Waste-Management Education and Research Consortium of New Mexico on the campus of Navajo Community College, focuses on environmental geology, hydrology, and resource management of the Colorado Plateau drylands. (DMM)

Semken, Steven C.

1992-01-01

144

Collapsing the Fear of Mathematics: A Study of the Effects of Navajo Culture on Navajo Student Performance in Mathematics  

ERIC Educational Resources Information Center

Collapsing the Fear of Mathematics: A Study of the Effects of Navajo Culture on Navajo Student Performance in Mathematics by Henry H Fowler Abstract American schools are in a state of "mediocrity" because of the low expectations in math (National Commission on Excellence in Education, 1983; No Child Left Behind Act of 2001; Duncan, 2009).…

Fowler, Henry H.

2010-01-01

145

Pennsylvanian to Jurassic eolian transportation systems in the western United States  

USGS Publications Warehouse

The direction of sediment transport in eolian sandstones of Pennsylvanian to Jurassic age was interpreted from crossbedding resultants (vector means) obtained from studies of eolian rocks in the western U.S., supplemented by data from the few eolian units of eastern North America. These were compiled from the published or unpublished (theses) literature, from unpublished field data contributed by colleagues, or from measurements made for this study. In addition, new paleogeographic maps were compiled to evaluate the influence of geographic features on the atmospheric circulation patterns that are inferred from the crossbedding studies. Regionally, the crossbedding indicates northeasterly, northerly, or northwesterly winds (present coordinates) from Pennsylvanian through most of Middle Jurassic time. A rather abrupt change in wind directions occurred in late Middle Jurassic time (late part of the Callovian Age) when westerly wind patterns developed. By the Late Jurassic the winds shifted to southwesterly. Calculations of the consistency factor (vector mean strength) made from region-wide analyses of the resultants indicate fairly unidirectional winds from the Pennsylvanian through the Early Jurassic. Middle Jurassic circulation was more varied, judging from crossbedding studies in the lower part of the Entrada Sandstone. Crossbedding in Upper Jurassic eolian rocks of Wyoming and South Dakota yielded a random pattern but Upper Jurassic rocks farther south on the Colorado Plateau and adjoining areas show a return to a fairly unidirectional pattern. Comparing the resultants with their reconstructed paleogeographic setting shows surprisingly little influence of major geographic features on overall circulation patterns. However, the greatest amount of local variation occurred at or near highly indented shorelines where the temperature contrast between land and water produces local wind currents that may vary appreciably from regional circulation patterns. Although they do not cause noticeable horizontal deflections in wind patterns, small and low topographic highs appear to be able to promote the development of a dune field if a source of sand is available and if streams do not enter the growing dune field. ?? 1988.

Peterson, F.

1988-01-01

146

Navajo coal and air quality in Shiprock, New Mexico  

USGS Publications Warehouse

Among the Navajo people, high levels of respiratory disease, such as asthma, exist in a population with low rates of cigarette smoking. Air quality outdoors and indoors affects respiratory health. Many Navajo Nation residents burn locally mined coal in their homes for heat, as coal is the most economical energy source. The U.S. Geological Survey and Dine College, in cooperation with the Navajo Division of Health, are conducting a study in the Shiprock, New Mexico, area to determine if indoor use of this coal might be contributing to some of the respiratory health problems experienced by the residents. Researchers in this study will (1) examine respiratory health data, (2) identify stove type and use, (3) analyze samples of coal that are used locally, and (4) measure and characterize air quality inside selected homes. This Fact Sheet summarizes the interim results of the study in both English and Navajo. This Fact Sheet is available in three versions: * English [800-KB PDF file ] * Navajo [computer must have Navajo language fonts installed - 304-KB PDF file] * Image of the Navajo language version [19.8-MB PDF file

Bunnell, Joseph E.; Garcia, Linda V.

2006-01-01

147

Diagenetic pathways for sandstones: The role of initial composition  

SciTech Connect

The initial composition of a clastic section is critical in determining the diagenetic reactions that a sandstone will undergo during burial, reactions which strongly influence its reservoir properties. The role of initial composition is illustrated for Middle Jurassic sandstones of northwest Europe (including the Brent sandstone of the North Sea) and Tertiary sandstones of the Gulf of Mexico. The composition of the former evolves from arkose to quartz arenite, with massive dissolution first of plagioclase and subsequently K-feldspar. As the bulk composition changes, the suite of clay minerals changes from kaolinite-dominated to illite-dominated, suite of clay minerals changes from kaolinite-dominated to illite-dominated, typically accompanied by a pronounced decrease in permeability. The Gulf of Mexico sandstones are also initially arkoses. Their composition, however, evolves toward a mixture of quartz and compositionally pure albite. Kaolinite remains the dominant authigenic clay within the sandstones; however detrital clays change from a Na-rich, smectitic mixed layer clay to a K-rich, illitic mixed layer clay. The contrasting diagenetic pathways result from differing mineralogy in the clastic section. The smectite-rich mudstones in the Gulf of Mexico provide a powerful sink for potassium and source of sodium. The resulting low potassium activity results in K-feldspar dissolution; it also prevents illite formation, while high sodium activity stabilizes albite. The Middle Jurassic clastic section in northwest Europe contains relatively little smectite, thus lacks the potassium sink and sodium source. Sodium activity is low, so plagioclases preferentially dissolve. K-feldspars also dissolve, but the potassium here is available for illite formation.

Harris, N.B. [Pennsylvania State Univ., University Park, PA (United States)

1995-09-01

148

Bryce Canyon Sandstone  

USGS Multimedia Gallery

Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolomite that caps them and the sandstone that forms their base. Bryce Canyon is also home to large numbe...

149

Snow-covered Sandstone  

USGS Multimedia Gallery

Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolomite that caps them and the sandstone that forms their base. Bryce Canyon is also home to large numbe...

150

Capitol Reef Sandstone Monolith  

USGS Multimedia Gallery

A sandstone monolith within Capitol Reef National Park. Capitol Reef is primarily made up of sandstone formations within the Waterpocket Fold, monocline that extends nearly 100 miles. A monocline is a step-like fold in rock strata that can resemble an enormous wrinkle in the earth....

151

Capitol Reef Sandstone Cliff  

USGS Multimedia Gallery

A sandstone cliff within Capitol Reef National Park. Capitol Reef is primarily made up of sandstone formations within the Waterpocket Fold, monocline that extends nearly 100 miles. A monocline is a step-like fold in rock strata that can resemble an enormous wrinkle in the earth....

152

Treatment of sandstone formations  

Microsoft Academic Search

A method of treating a subterranean sandstone formation with an aqueous acid solution containing hydrofluoric acid is described. The reaction rate of the acid with the formation is retarded and substantial penetration of the formation with active acid results. When the hydrofluoric acid solution contacts the sandstone formation, siliceous minerals and clay in the formation are dissolved, thereby increasing the

J. A. Knox; R. M. Lasater

1974-01-01

153

Origins of relief along contacts between eolian sandstones and overlying marine strata  

SciTech Connect

Origins of large-scale relief along eolian-marine unit contacts, which form significant stratigraphic traps for hydrocarbons, can be recognized as inherited, reworked, and/or erosional. The Permian Rotliegende-Weissliegende Sandstone and Yellow Sands of Europe may best exemplify inherited relief in that dunes are preserved largely intact. Reworked relief, which shows significant destruction of original dune topography but with remnants of the bedforms preserved, is shown by relict Holocene dunes of coastal Australia, the Jurassic Entrada Sandstone of the San Juan basin, and the Pennsylvanian-Permian Minnelusa Formation of Wyoming. Erosional relief results from post-eolian processes and is exemplified by the Jurassic Entrada Sandstone of northeastern Utah. 11 figs., 1 tab.

Eschner, T.B.; Kocurek, G.

1988-08-01

154

Comparison of geology of Jurassic Norphlet Mary Ann field, Mobile Bay, Alabama, to onshore regional Norphlet trends  

Microsoft Academic Search

The geology of the Mary Ann field is better understood in light of regional studies, which help to establish a depositional model in terms of both facies and thickness variations. These studies also illustrate major differences between onshore and offshore Norphlet deposits concerning topics such as diagenesis, hydrocarbon trapping, and migration. The Jurassic Norphlet sandstone was deposited in an arid

M. Marzono; G. Pense; P. Andronaco

1988-01-01

155

The Nature of Optional Sibilant Harmony in Navajo  

E-print Network

This thesis represents investigates optional sibilant harmony in Navajo using the first person possessive morpheme, which contains an underlyingly palatal sibilant that may harmonize to alveolar when affixed to noun stems ...

Berkson, Kelly Harper

2010-12-03

156

TECHNICAL SUPPORT TO NAVAJO NATION ON URANIUM MINING TENORM WASTES.  

EPA Science Inventory

Assistance is being provided to the Navajo Nation to establish its own radiation protection standards, radiation action levels, identification of safe drinking water sources, safe disposal of radioactive TENORM wastes from abandoned uranium mines, and to locate and decontaminate ...

157

Navajo coal and air quality in Shiprock, New Mexico  

USGS Publications Warehouse

Among the Navajo people, high levels of respiratory disease, such as asthma, exist in a population with low rates of cigarette smoking. Air quality outdoors and indoors affects respiratory health. Many Navajo Nation residents burn locally mined coal in their homes for heat, as coal is the most economical energy source. The U.S. Geological Survey and Dine College, in cooperation with the Navajo Division of Health, are conducting a study in the Shiprock, New Mexico, area to determine if indoor use of this coal might be contributing to some of the respiratory health problems experienced by the residents. Researchers in this study will (1) examine respiratory health data, (2) identify stove type and use, (3) analyze samples of coal that are used locally, and (4) measure and characterize air quality inside selected homes. This Fact Sheet summarizes the interim results of the study in both English and Navajo.

Bunnell, Joseph E.; Garcia, Linda V.

2006-01-01

158

Mask of the Black God The Pleiades in Navajo Cosmology  

NSDL National Science Digital Library

One Navajo legend attributes the creation of the primary stars and constellations to "Black God." Today, a famous star cluster, the Pleiades, often appears on the traditional mask worn by chanters impersonating Black God during special ceremonies. In this case study, designed for an observational astronomy class or introductory astronomy class with a strong observational component, students learn about the Pleiades in Navajo cosmology while developing their observation and star map skills.

Teresa M. Schulz

2005-01-01

159

Assistive Technology Provision Within the Navajo Nation  

PubMed Central

In this study we explored the factors that affect assistive technology (AT) provision within the Navajo Nation using a qualitative approach to inquiry. Focus groups were held in which AT users discussed their awareness of AT and their need for, use of, and satisfaction with AT devices and services. Twenty-eight individuals who used wheelchairs, orthotics or prosthetics, hearing aids, communication aids, vision aids, and other AT participated in one of seven focus groups. Seven AT providers discussed the facilitators and barriers that affect AT provision. The findings revealed six themes common to both stakeholder groups and two additional themes for AT users. The central theme for AT users centered on (not) feeling understood; the central theme for AT providers revolved around the processes, activities, and roles the providers engaged in at times for different clients. Activities to increase awareness and to promote successful AT provision and satisfaction with AT devices were proposed. PMID:25147224

Ripat, Jacquie D.

2014-01-01

160

Jurassic Polar Movement Relative to North America  

Microsoft Academic Search

Previous palcomagnetic studies of Jurassic rocks have not given concordant results and have led to the conclusion that the Jurassic pole position was possibly close to the present geographic pole. To test that supposition, the Kayenta, Carmel, Entrada, and Summerville formations were sampled from the extensive Jurassic sedimentary sequence in eastern Utah. The Lower and Upper Jurassic Kayenta and Summerville

ANY C. E. HELSLEY

1972-01-01

161

Middle Jurassic sand reservoirs of Tazovskoe field (West Siberia)  

NASA Astrophysics Data System (ADS)

Perspectives of Tazovskoe field Jurassic strata development are associated with lithological and mineralogical characteristics of reservoirs, which are the main reserve of the region, because of the high rate of depletion of the most prolific Cenomanian gas pools. Tazovskoye field is multibedded and is unique in terms of hydrocarbon reserves. Middle Jurassic strata occur everywhere and are represented by rocks of the Tyumenskaya formation, comprising layers J2 - J5. The producing horizons are composed of sandstones, sandy siltstones, cemented by shaly-carbonate cement mass. According to laboratory data, the Jurassic reservoirs are characterized by a wide range of porosity (up to 22.5%) and mainly low permeability (up to 2 mD), except for a few samples of J3 reservoir with permeability up to 100-150 mD. Test objects were the core samples taken from 7 intervals of the well T-83 and logging data from 4 intervals of wells 73, 93 in the Tazovskoye field. Depth and core recovery from T-83 well of the Tazovskoye field are shown in Table 1. Total linear core recovery from the Jurassic strata was 79.4 m. Late Bajocian-Bathonian alluvial-lacustrine strata compose the first regressive cycle of sedimentation in the Tazovskoye field. They are represented by alternating thin sandy, siltstone-sandy, siltstone, shaly-siltstone, siltstone-shaly, and shaly rocks with coal interbeds. They include three main productive formations: J2, J3 and J4. Above in the vertical section, the Upper Jurassic rocks occur, while lower, basal strata of the Callovian stage overlay them with a distinct unconformity. In the Upper Jurassic time, the main transgression phase of the Jurassic period occurred over the whole territory of the Western Siberia. These strata are built by non-uniform alternating sandstones, siltstones and shales with coal interbeds of the continental genesis (alluvial-lacustrine); The reservoirs contain cyclites that as a rule have binary structure, less often - ternary structure: the lower element of cyclites is represented by sandy and siltstone-sandy strata formed in a channel and in a point-bar, the upper element of cyclites is represented by siltstone, siltstone-shaly, shaly, and carbonaceous-shaly strata formed in the floodplain or in lacustrine-boggy sedimentation environment; The producing strata of J2-J4 formations are characterized in general by moderate porosity (11-17%) and low permeability (1 mD); This genetic type of the Middle Jurassic reservoirs is typical throughout the Pur-Taz petroleum region, as well is possible for the Nadym-Pur petroleum region, except for the most eastern areas of Nadym, where these rocks have flysch nature, and therefore one can predict their presence in adjacent fields, where the Jurassic reservoirs are not discovered yet.Core recoveries from T83 well;

Kurasov, I. A.

2012-12-01

162

Long term effects of CO2 on 3-D pore structure and 3-D phase distribution in reservoir sandstones from the Green River well (Utah, USA)  

NASA Astrophysics Data System (ADS)

Reservoir sandstones and cap rocks from the Green River area in Utah (USA) have been naturally exposed to CO2 fluids for hundreds of thousands of years, leading to compositional and microstructural alterations of the rocks. A 300m long section of this section of these Green river reservoir and cap rocks has been cored in 2012. Here, results of a high-resolution micro X-ray tomography study of a suite of samples from the well are reported detailing the 3D pore structure and phase distribution changes due to long term CO2 exposure. The reservoir sandstones from the Green River well (Utah) reveal the presence of various degrees of carbonate precipitation in the pores. Both reservoir sandstones (the shallower Entrada Formation and the deeper Navajo Formation) show variations in carbonate content and porosity structure. The Entrada sandstone exhibits widespread carbonate precipitation (up to 60% of infill of the original porosity), with the largest amount of carbonates at the boundary with the underlying Carmel cap rock. In an interval of a meter from the contact, carbonate precipitation decreases sharply till ~20%. The porosity is significantly reduced in the lowest 1 meter. The reduction in porosity lead to a reduction in pore connectivity and thereby permeability by the long-term CO2 exposure. On the other hand the Navajo sandstone shows predominantly only isolated spots of carbonate precipitation (up to 20% of the original porosity). Widespread carbonate precipitation is absent in the Navajo reservoir sandstone samples. Because carbonate precipitation is not present throughout, the large-scale permeability of the formation is likely not significantly affected by the CO2 exposure. The results show how the 3D distribution of the phases and the 3D shapes of the pores are affected by long term CO2 exposure and can be used as an example for potential changes to be expected in reservoir sandstones due to CO2 storage in future CO2 sequestration endeavours.

Barnhoorn, Auke; Kisoensingh, Shailesh

2014-05-01

163

Controls on the variability of net infiltration to desert sandstone  

USGS Publications Warehouse

As populations grow in and climates and desert bedrock aquifers are increasingly targeted for future development, understanding and quantifying the spatial variability of net infiltration becomes critically important for accurately inventorying water resources and mapping contamination vulnerability. This paper presents a conceptual model of net infiltration to desert sandstone and then develops an empirical equation for its spatial quantification at the watershed scale using linear least squares inversion methods for evaluating controlling parameters (independent variables) based on estimated net infiltration rates (dependent variables). Net infiltration rates used for this regression analysis were calculated from environmental tracers in boreholes and more than 3000 linear meters of vadose zone excavations in an upland basin in southwestern Utah underlain by Navajo sandstone. Soil coarseness, distance to upgradient outcrop, and topographic slope were shown to be the primary physical parameters controlling the spatial variability of net infiltration. Although the method should be transferable to other desert sandstone settings for determining the relative spatial distribution of net infiltration, further study is needed to evaluate the effects of other potential parameters such as slope aspect, outcrop parameters, and climate on absolute net infiltration rates. Copyright 2007 by the American Geophysical Union.

Heilweil, V.M.; McKinney, T.S.; Zhdanov, M.S.; Watt, D.E.

2007-01-01

164

Gas play opportunities in deeper Jurassic sequences of the Neuquen basin embayment, Argentina  

Microsoft Academic Search

We have defined new gas plays at around 4000 m depth near the giant Loma La Lata gas field. The plays, in lower Jurassic sandstones, were developed using a different approach in stratigraphic signatures as well as deformation styles. Two initial rifting stages led to the Triassic-Early Liassic volcanoclastic deposition (Precuyo s.l.) into a suite of discrete half-grabens. The late

F. Fernandez-Seveso; D. E. Figueroa; H. Rodriguez

1996-01-01

165

25 CFR 161.101 - How will tribal laws be enforced on the Navajo Partitioned Lands?  

Code of Federal Regulations, 2011 CFR

... 2011-04-01 false How will tribal laws be enforced on the Navajo Partitioned Lands...LANDS GRAZING PERMITS Tribal Policies and Laws Pertaining to Permits § 161.101 How will tribal laws be enforced on the Navajo Partitioned...

2011-04-01

166

25 CFR 161.101 - How will tribal laws be enforced on the Navajo Partitioned Lands?  

Code of Federal Regulations, 2010 CFR

... 2010-04-01 false How will tribal laws be enforced on the Navajo Partitioned Lands...LANDS GRAZING PERMITS Tribal Policies and Laws Pertaining to Permits § 161.101 How will tribal laws be enforced on the Navajo Partitioned...

2010-04-01

167

40 CFR 147.3400 - Navajo Indian lands-Class II wells.  

Code of Federal Regulations, 2010 CFR

...three satellite reservations (Alamo, Canoncito and Ramah), but excluding the former Bennett Freeze Area, the Four Corners Power Plant and the Navajo Generating Station; and on Navajo Nation tribal trust lands and trust allotments outside...

2010-07-01

168

25 CFR 161.101 - How will tribal laws be enforced on the Navajo Partitioned Lands?  

Code of Federal Regulations, 2014 CFR

... 2014-04-01 false How will tribal laws be enforced on the Navajo Partitioned Lands...LANDS GRAZING PERMITS Tribal Policies and Laws Pertaining to Permits § 161.101 How will tribal laws be enforced on the Navajo Partitioned...

2014-04-01

169

25 CFR 161.101 - How will tribal laws be enforced on the Navajo Partitioned Lands?  

Code of Federal Regulations, 2013 CFR

... 2013-04-01 false How will tribal laws be enforced on the Navajo Partitioned Lands...LANDS GRAZING PERMITS Tribal Policies and Laws Pertaining to Permits § 161.101 How will tribal laws be enforced on the Navajo Partitioned...

2013-04-01

170

25 CFR 161.101 - How will tribal laws be enforced on the Navajo Partitioned Lands?  

Code of Federal Regulations, 2012 CFR

... 2011-04-01 true How will tribal laws be enforced on the Navajo Partitioned Lands...LANDS GRAZING PERMITS Tribal Policies and Laws Pertaining to Permits § 161.101 How will tribal laws be enforced on the Navajo Partitioned...

2012-04-01

171

78 FR 41012 - Approval of Air Quality Implementation Plans; Navajo Nation; Regional Haze Requirements for...  

Federal Register 2010, 2011, 2012, 2013, 2014

...The Navajo Nation, Gila River Indian Community, and other affected stakeholders...the Navajo Nation and Gila River Indian Community, describing the development...Nation, Hopi Tribe, the Gila River Indian Community, and numerous other...

2013-07-09

172

The Science Behind Jurassic Park  

NSDL National Science Digital Library

"The Science Behind Jurassic Park" is an html document describing how world renowned paleontologist Jack Horner is using computers and CAT scan machines to peer inside 30 million year old dinosaur fossils.

173

New Late Jurassic and Middle Carboniferous Paleomagnetic Results from the Junggar Basin, NW China  

NASA Astrophysics Data System (ADS)

The Junggar Basin of northwestern China, often considered to be the southeast extremity of the Kazakhstan Block, sits in a complicated region squeezed between the Tarim Basin on the south, the Kazakhstan Block on the west, and Siberia to the northeast. New paleomagnetic data from several Late Jurassic and Middle Carboniferous rock units from the Junggar Basin suggest that the Junggar basin was close to Tarim Basin but quite far south away from Kazakhstan and Siberia. We have obtained preliminary paleomagnetic results from Late Jurassic and Middle Carboniferous rocks sampled over a large area in eastern Junggar basin. After removal of a low-temperature component that resembles both Tertiary and present field directions and fails fold test, a stable high temperature characteristic component (ChRM) remains in Late Jurassic sandstone Shishu and Xishanyao Formations, and Middle Carboniferous red sandstone and andesite Bataimayiruishan Formation. The ChRM has both normal and reversed magnetic polarities and passes local fold tests at high levels of confidence. The corresponding paleopoles place Junggar basin at paleolatitudes of 34.6 N and 19.5N in Late Jurassic and Middle Carboniferous time, respectively, suggesting that Junggar basin and its northern neighboring blocks (Kazakhstan and Siberia) have not maintained their relative positions since Middle Carboniferous.

Finn, D. R.; Zhao, X.; Li, J.

2009-12-01

174

Middle Jurassic incised valley fill (eolian/estuarine) and nearshore marine petroleum reservoirs, Powder River basin  

SciTech Connect

Paleovalleys incised into the Triassic Spearfish Formation (Chugwater equivalent) are filled with a vertical sequence of eolian, estuarine, and marine sandstones of the Middle Jurassic (Bathonian age) Canyon Springs Sandstone Member of the Sundance Formation. An outcrop exemplifying this is located at Red Canyon in the southern Black Hills, Fall River County, South Dakota. These paleovalleys locally have more than 300 ft of relief and are as much as several miles wide. Because they slope in a westerly direction, and Jurassic seas transgressed into the area from the west there was greater marine-influence and more stratigraphic complexity in the subsurface, to the west, as compared to the Black Hills outcrops. In the subsurface two distinctive reservoir sandstone beds within the Canyon Springs Sandstone Member fill the paleovalleys. These are the eolian lower Canyon Springs unit (LCS) and the estuarine upper Canyon Springs unit (UCS), separated by the marine {open_quotes}Limestone Marker{close_quotes} and estuarine {open_quotes}Brown Shale{close_quotes}. The LCS and UCS contain significant proven hydrocarbon reservoirs in Wyoming (about 500 MMBO in-place in 9 fields, 188 MMBO produced through 1993) and are prospective in western South Dakota, western Nebraska and northern Colorado. Also prospective is the Callovian-age Hulett Sandstone Member which consists of multiple prograding shoreface to foreshore parasequences, as interpreted from the Red Canyon locality. Petrographic, outcrop and subsurface studies demonstrate the viability of both the Canyon Springs Sandstone and Hulett Sandstone members as superior hydrocarbon reservoirs in both stratigraphic and structural traps. Examples of fields with hydrocarbon production from the Canyon Springs in paleovalleys include Lance Creek field (56 MMBO produced) and the more recently discovered Red Bird field (300 MBO produced), both in Niobrara County, Wyoming.

Ahlbrandt, T.S. [Geological Survey, Denver, CO (United States); Fox, J.E. [South Dakota School of Mines, Rapid City, SD (United States)

1997-07-01

175

STEM Summer Academy on the Navajo Reservation  

NASA Astrophysics Data System (ADS)

The US Rosetta Project is the NASA contribution to the International Rosetta Mission, an ESA cornerstone mission to comet Churyumov-Gerasimenko. While the project's outreach efforts span multi-media, and a variety of age and ethnic groups, a special emphasis has been made to find a way to provide meaningful outreach to the reservation communities. Because language preservation is an issue of urgent concern to the reservation communities, and because Rosetta, uniquely among NASA missions, has been named after the notion that keys to missing understanding of elements of the ancient past were found in the language on the original Rosetta stone, the US Rosetta Project has embarked upon outreach with a focus on STEM vocabulary in ancient US languages of the Navajo, Hopi, Ojibwe, and other tribal communities as the project expands. NASA image and science are used and described in the native language, alongside lay English and scientific English curriculum elements. Additionally, science (geology/chemistry/botany/physics) elements drawn from the reservation environment, including geomorphology, geochemistry, soil physics, are included and discussed in the native language as much as possible — with their analogs in other planetary environments (such as Mars). In this paper we will report on the most recent Summer Science Academy [2012], a four week summer course for middle school children, created in collaboration with teachers and administrators in the Chinle Unified School District. The concept of the Academy was initiated in 2011, and the first Academy was conducted shortly thereafter, in June 2011 with 14 children, 3 instructors, and a NASA teacher workshop. The community requested three topics: geology, astronomy, and botany. The 2012 Academy built on the curriculum already developed with more robust field trips, addressed to specific science topics, additional quantitative measurements and activities, with more written material for the cultural components from Navajo contributors. In 2012, the Academy was conducted with 45 children and 4 instructors. Following up on lessons learned in previous reports, it is clear that community involvement and buy-in is critical to the success of the program. This means that the US Rosetta Project modified its goals and curriculum to accommodate the teaching desires of teachers in the district, and the capabilities of the medicine men that agreed to participate. The use of NASA material and imagery can be shown to have a positive impact on the accessibility of the overall STEM material. Metrics used in the program will be discussed. Future work to extract STEM language elements to enhance the program will include organized Elder's Round Tables for discussion, and recording, of language with first speakers. Work on this project was supported by NASA at California Institute of Technology/Jet Propulsion Laboratory.

Alexander, C. J.

2012-12-01

176

Characterization and mischaracterization of authigenic magnesium-bearing minerals: Examples from Norphlet Sandstone, Alabama, Florida, and Mississippi  

Microsoft Academic Search

Jurassic Norphlet sandstones are significant gas, condensate, and carbon dioxide reservoirs in the eastern Gulf Coast region. Diagenetic factors affecting the quality of these reservoirs are variable at microscopic to megascopic scales. Major authigenic components of the reservoirs include quartz, albite, K-feldspar, a variety of carbonate minerals, anhydrite, pyrite, illite, and chlorite; minor components include zeolite, tourmaline, apatite, and anatase.

1993-01-01

177

Peer Group Evaluation of Narrative Competence: A Navajo Example. Working Papers in Sociolinguistics, No. 47.  

ERIC Educational Resources Information Center

The narrative performances of Navajo children were examined to determine the ways in which the skills of competently structuring a narrative are informally learned within the peer group. Ten- and eleven-year-old Navajo children, living near Window Rock, Arizona, were evaluated in telling stories about the most traditional figures of Navajo belief,…

Brady, Margaret

178

A Little History of North American Indians: The Navajos. New Edition.  

ERIC Educational Resources Information Center

This reprint of a 1909 volume portrays the life and history of the Navajo people, based on the personal experiences of an unusually enlightened white observer. The first three chapters cover the Navajo's early history, discovery by Spanish explorers, evidence of a prehistoric and possibly ancestral race, and the beauties of the Navajo's rugged…

Lipps, Oscar H.

179

The Construction of an Intercultural Sensitizer Training Non-Navajo Personnel.  

ERIC Educational Resources Information Center

The Navajo Intercultural Sensitizer consists of 48 "critical incidents" of cross-cultural conflict and possible interpretations, presented in a programed learning format. Initial interpretations of the incidents differed significantly between similarly educated Anglos and Navajos overall, but not between Anglos and younger (under age 30) Navajos.…

Salzman, Michael B.

1990-01-01

180

Students' Perspectives on Navajo Language and Learning: Voices of the Students  

ERIC Educational Resources Information Center

To determine if Navajo language classes made a difference in students' lives, thirty Navajo language and culture students were selected to be interviewed. The students selected were those who were in the language and culture programs in the elementary, middle and high school. The focus was to find out the students' perspectives on Navajo

Shepard, Marlena

2012-01-01

181

Stephannie and the Coyote (Stefanii doo Ma'ii) in Navajo and English.  

ERIC Educational Resources Information Center

Intended as a supplementary text or a library book for Navajo children, this book is written both in English and Navajo. Color pictures illustrate each passage in the text. The pictures graphically depict the living conditions of the Navajo people. (TL)

Crowder, Jack L.

182

Naalyehe Ba Hooghan--"House of Merchandise": The Navajo Trading Post as an Institution of Cultural Change, 1900 to 1930.  

ERIC Educational Resources Information Center

Navajo Reservation trading posts held an influential position between two cultures and operated on Navajo terms but also were an assimilative force emphasizing white values through the marketing of Navajo wool and rugs, traffic in prehistoric artifacts, and employment of Navajos in a mixed barter and wage economy. (SV)

McPherson, Robert S.

1992-01-01

183

The Scalpel and the Silver Bear. The First Navajo Woman Surgeon Combines Western Medicine and Traditional Healing.  

ERIC Educational Resources Information Center

In this autobiography, Lori Arviso Alvord describes her journey to become the first Navajo woman surgeon and her realization of the benefits of Navajo philosophy to the healing process. Raised on the Navajo reservation by a White mother and a Navajo father and grandmother, Alvord learned to walk in two worlds. Encouraged to get an education, she…

Alvord, Lori Arviso; Van Pelt, Elizabeth Cohen

184

Frisco City sand: New Jurassic reservoir in southwest Alabama  

SciTech Connect

The first commercial production of hydrocarbons from the Jurassic Haynesville Formation in southwestern Alabama was from the Frisco City field. The field currently produces 57.8{degree} API gravity oil on 160-ac well spacing from a depth of approximately 12,000 ft. Perforations are in the Frisco City sand interval, in the lower part of the Haynesville Formation. Average porosity is 15% and average permeability is 45 md. Currently, the field has two producing wells with cumulative production of over 138,876 bbl of oil and 213,144 mcf of gas. The hydrocarbon trap in the Frisco City field is a combination structural-stratigraphic trap. The Frisco City sand reservoir is located on a faulted anticline. The stratigraphic trap is produced by a permeability barrier near the crest of the structure and termination against a basement high. The lower part of the Haynesville Formation in this area is comprised of (in ascending order) the Buckner Anhydrite Member, the Frisco City sand, and interbedded shale and anhydrite. Sandstones of the Frisco City sand interval were deposited in a shallow marine setting and have a sheetlike morphology. The sandstones are poorly to moderately sorted, angular to rounded arkose, and contain angular to rounded pebbles. The sandstones are interbedded with thin, sandy, mudstones that contribute, along with patchy carbonate and anhydrite cement, to considerable reservoir heterogeneity. Porosity is predominantly primary intergranular with a small amount of framework grain dissolution and decementation.

Mann, S.D.; Mink, R.M.; Bearden, B.L. (Geological Survey of Alabama, Tuscaloosa (USA)); Schneeflock, R.D. Jr. (Paramount Petroleum Co., Inc., Jackson, MS (USA))

1989-09-01

185

Navajo-Hopi Land Commission Renewable Energy Development Project (NREP)  

SciTech Connect

The Navajo Hopi Land Commission Office (NHLCO), a Navajo Nation executive branch agency has conducted activities to determine capacity-building, institution-building, outreach and management activities to initiate the development of large-scale renewable energy - 100 megawatt (MW) or larger - generating projects on land in Northwestern New Mexico in the first year of a multi-year program. The Navajo Hopi Land Commission Renewable Energy Development Project (NREP) is a one year program that will develop and market a strategic business plan; form multi-agency and public-private project partnerships; compile site-specific solar, wind and infrastructure data; and develop and use project communication and marketing tools to support outreach efforts targeting the public, vendors, investors and government audiences.

Thomas Benally, Deputy Director,

2012-05-15

186

Geographic information system (G.I.S.) research project at Navajo Community College - Shiprock Campus  

SciTech Connect

The Navajo and Hopi GIS Project was established to assess the feasibility and impact of implementing GIS techology at Tribal institutions. Los Alamos and Lawrence Livermore National Laboratories funded the Navajo and Hopi Geographic Information System (G.I.S.) Project and assigned a mentor from LANL to help guide the project for three summer months of 1995. The six organizations involved were: LANL, LLNL, Navajo Community College, Navajo Nation Land Office, Northern Arizona University and San Juan College. The Navajo Land Office provided the system software, hardware and training. Northern Arizona University selected two students to work at Hopi Water Resource Department. Navajo Community College provided two students and two faculty members. San Juan College provided one student to work with the N.C.C. group. This made up two project teams which led to two project sites. The project sites are the Water Resource Department on the Hopi reservation and Navajo Community College in Shiprock, New Mexico.

Yazzie, R.; Peter, C.; Aaspas, B.; Isely, D.; Grey, R.

1995-12-31

187

A Jurassic mammal from South America  

Microsoft Academic Search

The Jurassic period is an important stage in early mammalian evolution, as it saw the first diversification of this group, leading to the stem lineages of monotremes and modern therian mammals. However, the fossil record of Jurassic mammals is extremely poor, particularly in the southern continents. Jurassic mammals from Gondwanaland are so far only known from Tanzania and Madagascar, and

Oliver W. M. Rauhut; Thomas Martin; Edgardo Ortiz-Jaureguizar; Pablo Puerta

2002-01-01

188

Ages of zircons from Jurassic sediments of Bluefish River slope, NWT Canada, and the possible age of kimberlite activity on the Lena West property  

Microsoft Academic Search

This work is based on a study of 30 zircons extracted from the heavy mineral fraction of a sedimentary rock sample with anomalously high contents of well-preserved kimberlite indicator minerals (KIM). The sample was taken from the basal horizon of Jurassic?Cretaceous sandstones on the slope of Bluefish River valley. The Bluefish River, located in the Northwest Territories (Canada) north of

A. M. Agashev; S. S. Kuligin; Y. Orihashi; N. P. Pokhilenko; M. A. Vavilov; D. Clarke

2008-01-01

189

Lichen on Sandstone  

USGS Multimedia Gallery

Lichen on sandstone in Pine Creek Canyon. Lichen is a composite organism made up of algae and fungi, which form a symbiotic relationship. Pine Creek Canyon is a remnant ecosystem of loblolly pines. A remnant ecosystem is the last vestige of an ecosystem type that used to be more widespred. Red Roc...

190

Sandstone and Moon  

USGS Multimedia Gallery

Views along the Queen's Garden Trail in Bryce Canyon National Park. Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolomite that caps them and the sands...

191

The Navajo Way From High School To College.  

ERIC Educational Resources Information Center

Practical and precise advice and guidelines are detailed in this volume to assist Navajo high school students in their pursuit of a college education. Part I describes considerations when choosing a college and includes a college selection worksheet. Part II outlines college admissions procedures with emphasis on A.C.T. registration and testing,…

Noon, John

192

Origin of coexisting minette and ultramafic breccia, Navajo volcanic field  

Microsoft Academic Search

Trace element evidence indicates that at the Buell Park diatreme, Navajo volcanic field, the felsic minette can be best explained by crystal fractionation from a potassic magma similar in composition to the mafic minettes. Compatible trace element (Cr, Ni, Sc) abundances decrease while concentrations of most incompatible elements (Ce, Yb, Rb, Ba, Sr) remain constant or increase from mafic to

Michael F. Roden

1981-01-01

193

Career Unit. The Art of Navajo Rug Weaving.  

ERIC Educational Resources Information Center

This career exploration instructional unit on Navajo rug weaving is one of several resulting from the rural southwestern Colorado CEPAC Project (Career Education Process of Attitude Change). This unit consists of (1) five unit objectives (to recognize the importance of sheep in the Indians' life, to realize the time required to prepare wool for…

Robb, Edna; And Others

194

Factors Influencing Recent Navajo and Hopi Population Changes  

ERIC Educational Resources Information Center

In this paper, population changes of 2 Southwestern American Indian tribes, the Navajos and the Hopis, are compared and it is suggested that the differences are accounted for both by Federal policy as it has effected each reservation's loss or acquisition land and, to a lesser degree, by the living arrangements of each tribe. (Author/KM)

Kunitz, Stephen J.

1974-01-01

195

Prevalence of Hepatitis A Virus Antibody Among Navajo School Children.  

ERIC Educational Resources Information Center

A serologic investigation of prevalence of immunity to hepatitis A (anti-HAV) was conducted in a rural school adjacent to a Navajo reservation in New Mexico. The results show rates of anti-HAV that are the highest reported at the ages tested in any subpopulation in the United States, comparable only with those in developing countries. (KH)

Williams, Robert

1986-01-01

196

"Dine Bizaad" (Navajo Language) at a Crossroads: Extinction or Renewal?  

ERIC Educational Resources Information Center

Until about 20 years ago, the Navajo language was one of the most resilient American Indian languages in modern U.S. history. Today, at the dawn of the 21st century, that has all changed. Some changes can be attributed to the normal dynamics of cultural transmission that affect language use. Some others, such as the dramatic shift toward English…

Benally, AnCita; Viri, Denis

2005-01-01

197

Technical Review of the Navajo Nation Drought Contingency  

E-print Network

Technical Review of the Navajo Nation Drought Contingency Plan ­ Drought Monitoring Michael-term Drought 7 Current Drought Monitoring Procedures: An examination of the 6-month SPI Drought Index 8 SPI and Drought Monitoring: Shorter vs. longer timescales 9 A Closer Look at the 6-month SPI 10 Precipitation

Neff, Jason

198

Project HOPE and Nursing at Navajo Community College.  

ERIC Educational Resources Information Center

After an in-depth study focusing on four major interdependent factors of the Navajo social system (the Origin Myth and the general mythology basic to the religious/medical practices, the economy, political system, and education), Project HOPE agreed, in cooperation with the college, to establish and implement an Associate of Arts nursing program…

Daniel, M. Grace

199

Effects of stratigraphic heterogeneity on permeability in eolian sandstone sequence, Page sandstone, northern Arizona  

SciTech Connect

Outcrop and core data from the eolian Middle Jurassic Page Sandstone of northern Arizona show that realistic reservoir characterization can be based on the stratigraphic architecture. Outcrop displays of differential weathering, coloration, cementation, and seepage reflect stratigraphic control of fluid flow within the sandstone. Measurements of permeability using a field permeameter and conventional analysis yield a five-order-of-magnitude range of values between distinct populations. Extra-erg and/or interdune deposits are least permeable (0.67-1800 md), followed by wind-ripple strata (900-5200 md), with grain-flow strata being the most permeable (3700-12,000 md). Extra-erg and interdune deposits and some extensive bounding surfaces form significant flow barriers and tend to compartmentalize the reservoir. Reservoir characteristics of the dune cross-strata are a function of the types, distributions, and orientations of the internal stratification. Directional-flow properties within the strata are most pronounced within wind-ripple laminae. Recognition of the levels of reservoir heterogeneity is sampling-scale dependent. General models for flow within single sets of cross-strata as well as within eolian sequences can be generated based upon relative permeability between stratigraphic units. 9 figures.

Chandler, M.A.; Kocurek, G.; Goggin, D.J.; Lake, L.W.

1989-05-01

200

Middle Jurassic strata link Wallowa, Olds Ferry, and Izee terranes in the accreted Blue Mountains island arc, northeastern Oregon  

SciTech Connect

Middle Jurassic strata atop the Wallowa terrane in northeastern Oregon link the Wallowa, Izee, and Olds Ferry terranes as related elements of a single long-lived and complex oceanic feature, the Blue Mountains island arc. Middle Jurassic strata in the Wallowa terrane include a dacitic ash-flow deposit and contain fossil corals and bivalves of North American affinity. Plant fossils in fluvial sandstones support a Jurassic age and indicate a seasonal temperate climate. Corals in a transgressive sequence traditionally overlying the fluvial units are of Bajocian age and are closely related to endemic varieties of the Western Interior embayment. They are unlike Middle Jurassic corals in other Cordilleran terranes; their presence suggests that the Blue Mountains island arc first approached the North American craton at high paleolatitudes in Middle Jurassic time. The authors consider the Bajocian marine strata and underlying fluvial volcaniclastic units to be a basin-margin equivalent of the Izee terrane, a largely Middle Jurassic (Bajocian) succession of basinal volcaniclastic and volcanic rocks known to overlie the Olds Ferry and Baker terranes.

White, J.D.L. (Dalhousie Univ., Halifax, Nova Scotia (Canada)); Vallier, T. (Geological Survey, Menlo Park, CA (United States)); Stanley, G.D. Jr. (Univ. of Montana, Missoula (United States)); Ash, S.R. (Weber State Univ., Odgen, UT (United States)); White, D.L.

1992-08-01

201

Replacement geometry and fabrics of Smackover (Jurassic) dolomite, southern Alabama  

SciTech Connect

The intensity of dolomitization and associated reservoir development in the Smackover Formation, Conecuh Ridge-Wiggens arch areas, is not predictable by comparison with time-temperature index methods or porosity-depth curves. Major alteration patterns and associated dolomite fabrics reflect the early paleotopographic settings, where high fluid flux and massive replacement are associated with Late Jurassic basement highs. This large-scale replacement is most important in the lowermost Smackover section overlying the Norphlet sandstone from Chunchula field into the Manila Embayment. The heterogeneous nature of dolomite reservoir development is evident in Chunchula field, where local pods of permeable dolomite cut across sedimentary facies boundaries. Predicting the orientation of a dolomite permeability barrier where there is little well control can be facilitated by mapping the regional thickness variations; the extension of impermeable dolomite trends is generally parallel to isopach trends.

Barrett, M.L.

1986-09-01

202

Dine bikeyah bik'ah (Navajo oil): An ethnohistory, 1922-1960  

NASA Astrophysics Data System (ADS)

Oil was discovered on the Navajo reservation in 1922, and as a result, the U.S. Department of the Interior pressured Navajos into leasing their lands to develop it. This study reveals that, at first, government officials hoped Navajos would quietly acquiesce, but instead Navajos fought for control. Moreover, oil development served as a basis for tribal debates over such issues as assimilation, land use, and the environment, especially the destruction of grazing areas and sacred sites. Manuscript collections and federal government documents provided the minutes of many tribal council meetings from 1923 to 1960, correspondence between Navajo, Interior Department, and oil company personnel, and royalty and leasing data. Research revealed a tremendous diversity of opinion not only between Navajos and non-Navajos, but between Navajos themselves. Interviews conducted in Farmington, Aztec, Gallup, and Albuquerque, New Mexico, added further complexity and provided local "color." The main difficulty, of course, was locating the Navajo voice and particularly the voices of those not involved in tribal government. A second problem was the paucity of accurate production and royalty documents. Oil company reports were not subject to verification during this period, so it is unlikely that those available provide correct figures. Moreover, oil companies deny possessing archives. This study attempts to balance Navajo and non-Navajo responses to oil development on reservation land from 1922 to 1960 and to suggest future research beyond this period. When dealing with two very diverse cultures, however, there is a tendency to vilify one of them and to examine the other uncritically, perhaps even romantically. Research revealed many complex individuals within both cultures, men and women with varying ambitions and viewpoints. This study presents a tumultuous period in Navajo history and focuses on the successes and failures, abilities and weaknesses of both Navajos and Anglo-Americans.

Chamberlain, Kathleen Patricia

1998-11-01

203

Origin of high-permeability reservoirs in Upper Minnelusa Sandstone (Permian) Powder River basin, Wyoming and Montana  

SciTech Connect

Petrographic analysis of samples from 8 Minnelusa cores from Campbell County, Wyoming, and Powder River County, Montana, reveals that high-permeability reservoirs (up to 3200 md) are the result of extensive dissolution of early precipitated gypsum or anhydrite cement. The Minnelusa reservoirs are in eolian sandstones (dune and interdune facies) that are very fine to coarse-grained, moderately to bimodally sorted quartz-arenites, subarkoses, and sublitharenites. Dune and interdune sandstones exhibit differences in detrital mineralogy that are the result of postdepositional dissolution of labile grains. The most common cements in the sandstone are anhydrite (0-30%), quartz overgrowths (0-10%), dolomite (0-10%), Kaolinite (< 5%), and illite (< 1%). Most cementation occurred during the pre-Jurassic when the sandstones were buried less than 1500 ft. The porosity network within the sandstone is a combination of primary and secondary porosity created by the dissolution of anhydrite cement. Burial history curves suggest that anhydrite dissolution occurred during the Late Jurassic to Early Cretaceous, when the top of the sandstones was still near the surface. During this time, 3 periods of uplift and erosion occurred in which meteoric waters undersaturated in calcium sulfate may have flowed through the sandstones. The distribution of the reservoirs is probably controlled by the regional structure during the periods of flushing. Dune sandstones are the most productive facies in the high-permeability reservoirs. Porosity in the dune facies averages 21% compared with an average of 9% in the interdune facies. This difference is the result of both lower depositional porosity and greater quartz and dolomite cementation in the interdune sandstones. Porosity loss due to mechanical compaction is similar for both facies.

Helmold, K.P.; Loucks, R.G.

1985-02-01

204

"Still, She Didn't See What I Was Trying to Say": Towards a History of Framing Navajo English in Navajo Written Poetry  

ERIC Educational Resources Information Center

This paper outlines the ways that Navajo poetry was framed in the late 1960s and early 1970s, as "unsophisticated" and non-literary by the introductory materials written by non-Native Americans for collections of Native American poetry. At issue was a view that saw the use of Navajo English, a distinctive vernacular dialect, as a deficient form of…

Webster, Anthony K.

2010-01-01

205

Reinterpreting the morphology of the Jurassic scorpion Liassoscorpionides.  

PubMed

The fossil scorpion (Arachnida: Scorpiones) Liassoscorpionides schmidti Bode, 1951, the youngest scorpion to be assigned to a putative aquatic clade, from the early Jurassic (Toarcian) of Hondelage near Braunschweig, Germany, is redescribed. It is the only unequivocal Jurassic scorpion, but there is in fact no evidence to support an aquatic mode of life. Some features hint that it might be the last of the mesoscorpions-a largely Palaeozoic lineage with a few Mesozoic "relict" taxa. Our reinvestigation revealed that the holotype was over-interpreted by Kjellesvig-Waering. Key characters in his redescription (e.g. eye position, chelicerae, gill slits, etc.) are dubious at best and we follow previous authors in treating L. schmidti as an incertae sedis species. To investigate the hypothesis that mesoscorpions were habitually terrestrial, macerated cuticle fragments originally assigned to Mesophonus infans E Wills, 1947 from the Late Triassic Lower Keuper Sandstone Series of Bromsgrove, UK were re-examined. These were drawn as having book lungs in the original description, but the original figures are misleading and the expected lung lamellae could not be resolved. PMID:18089103

Dunlop, Jason A; Kamenz, Carsten; Scholtz, Gerhard

2007-06-01

206

Exploration in Jurassic of North Mafla, eastern Gulf of Mexico  

SciTech Connect

Exploration in North Mafla focuses on general categories of prospects, potential reservoirs and their associated facies, and seismic modeling of available well control. Jurassic prospects in North Mafla can be classified into four general categories: (1) basement-related structures: (2) closures associated with the Pensacola-Destin peripheral fault trend, (3) salt anticlines, and (4) prospects associated with the interregional structural highs. Each of these categories can be related to documented, predictable, and repeated patterns of hydrocarbon accumulations in east Texas, north Louisiana, Mississippian, Alabama, and Florida. The primary objectives in North Mafla are the Jurassic Smackover carbonates and Norphlet sands at depths ranging rom 15,000 to 25,000 ft. Major gas accumulations in the Norphlet around Mobile Bay are separated from thicker sequences of Norphlet sands in the De Soto Salt basin by the offshore extension of the Pensacola arch. Seismic geometries suggest that Smackover high-energy carbonates may have been deposited on the crest of some of these thick Norphlet sands. Seismic modeling indicates that a high-amplitude, laterally continuous event associated with a Norphlet-Louann Salt contact is dependent on the presence of Pine Hill anhydrite member of the Louann Salt. In addition, seismic reflection geometries indicate that the Norphlet sandstone thickens from +/- 300 ft on the eastern flank of the Destin Dome to nearly 1000 ft nearby. Although drilling in the lightly explored Norch Mafla area has yielded few substantive results to date, the elements necessary for significant hydrocarbon accumulations are known to exist.

Kemmer, D.A.

1987-05-01

207

Recent Jurassic discoveries in southeastern Cass County, Texas  

SciTech Connect

Southeastern Cass County had lain virtually dormant as a prospective Jurassic oil and gas province since the mid-1960s, when East Linden field was discovered and developed. Then, in 1978, Hilliard Oil and Gas drilled the 1 Johnson and discovered Kildare field (Smackover). Subsequent development thru 1982 proved additional reserves in several Cotton Valley sandstones as well, reconfirming southeastern Cass County as territory for viable Jurassic drilling. Additional drilling occurred when Marshall Exploration redrilled and expanded the old Bloomburg field and Heflin redrilled Queen City field. All of this drilling was successful in the Smackover reservoir, finding sour gas and condensate. Wildcat activity included the two Smackover completions finding South Atlanta field, as well as two completions in formations that are highly debated as to their nomenclature. Cities Service reportedly their well in the Eagle Mills. This well brought national attention to southeastern Cass County, when it was reported on the CBS Saturday evening news. The well initially flowed at rates that were as high as 1800 BOPD, 1396 MCFGD, and 32 BWPD, with pressure of 3250 psi. Just as the excitement was dying down, Primary Fuels, Inc. reentered and deepened the Highland Resources 1 Glass and completed that well in a zone correlative to the Cities Service 1-A Pruitt. The 1 glass potentialed for 200 BOPD, 570 MCFGD, and 32 BWPD, at pressure of 2900 psi. The producing zone was determined to be the Norphlet, which once again was made wildcatters of all previous upper Smackover explorers.

Aubrey, J.

1984-09-01

208

Exploring stratigraphic traps: an example from the Upper Jurassic in Block 33\\/9, the Norwegian North Sea  

Microsoft Academic Search

Stratigraphic trapping potential is identified in Block 33\\/9 by the occurrence of a seismically well-defined Upper Jurassic anomaly interpreted to represent sands deposited in the hanging wall of a rotated fault block.This interpretation is supported by a fan-shaped morphology, very distinctive mounding and associated differential compaction observed on 3D seismic data. Similar oil-bearing sandstones have been penetrated in the Statfjord

Samir A. Ghazi; William J. Schmidt

1995-01-01

209

Paleosol caliche in the New Haven Arkose, Connecticut: Record of semiaridity in Late Triassic Early Jurassic Time  

Microsoft Academic Search

Recently discovered caliche paleosol profiles are widely distributed in braided-stream sandstone and overbank mudstone in the 1,500- to 2,500-m sequence of red beds in the New Haven Arkose. During Late Triassic to Early Jurassic time, the tropical rift valley commonly was semiarid with an annual 100 to 500 mm of seasonal precipitation. The paleoclimate was much drier than is indicated

John F. Hubert

1977-01-01

210

Paleolatitudes of the Tibetan Himalaya from primary and secondary magnetizations of Jurassic to Lower Cretaceous sedimentary rocks  

NASA Astrophysics Data System (ADS)

Tibetan Himalaya represents the northernmost continental unit of the Indian plate that collided with Asia in the Cenozoic. Paleomagnetic studies on the Tibetan Himalaya can help constrain the dimension and paleogeography of "Greater India," the Indian plate lithosphere that subducted and underthrusted below Asia after initial collision. Here we present a paleomagnetic investigation of a Jurassic (limestones) and Lower Cretaceous (volcaniclastic sandstones) section of the Tibetan Himalaya. The limestones yielded positive fold test, showing a prefolding origin of the isolated remanent magnetizations. Detailed paleomagnetic analyses, rock magnetic tests, end-member modeling of acquisition curves of isothermal remanent magnetization, and petrographic investigation reveal that the magnetic carrier of the Jurassic limestones is authigenic magnetite, whereas the dominant magnetic carrier of the Lower Cretaceous volcaniclastic sandstones is detrital magnetite. Our observations lead us to conclude that the Jurassic limestones record a prefolding remagnetization, whereas the Lower Cretaceous volcaniclastic sandstones retain a primary remanence. The volcaniclastic sandstones yield an Early Cretaceous paleolatitude of 55.5°S [52.5°S, 58.6°S] for the Tibetan Himalaya, suggesting it was part of the Indian continent at that time. The size of "Greater India" during Jurassic time cannot be estimated from these limestones. Instead, a paleolatitude of the Tibetan Himalaya of 23.8°S [21.8°S, 26.1°S] during the remagnetization process is suggested. It is likely that the remagnetization, caused by the oxidation of early diagenetic pyrite to magnetite, was induced during 103-83 or 77-67 Ma. The inferred paleolatitudes at these two time intervals imply very different tectonic consequences for the Tibetan Himalaya.

Huang, Wentao; van Hinsbergen, Douwe J. J.; Dekkers, Mark J.; Garzanti, Eduardo; Dupont-Nivet, Guillaume; Lippert, Peter C.; Li, Xiaochun; Maffione, Marco; Langereis, Cor G.; Hu, Xiumian; Guo, Zhaojie; Kapp, Paul

2015-01-01

211

Composition, provenance and source weathering of Mesozoic sandstones from Western-Central Mediterranean Alpine Chains  

NASA Astrophysics Data System (ADS)

Forty-two Mesozoic sandstone samples from three different sedimentary successions of the Internal Domains along the Western-Central Mediterranean Alpine Chains (Betic Cordillera, Rif Chain and Calabria-Peloritani Arc) were chemically analyzed to characterize their composition and the degree of weathering in the source area(s). The Rif Chain sandstones have SiO2 contents higher than those of the Calabria-Peloritani Arc and Betic Cordillera sandstones, whereas Al2O3 contents are higher in the Calabria-Peloritani Arc sandstones rather than in the Rif Chain and Betic Cordillera sandstones. The indices of compositional variability (ICV) of the studied samples are generally less than 1, suggesting that the samples are compositionally mature and were likely dominated by recycling. Recycling processes are also shown by the Al-Zr-Ti diagram indicating zircon addition and, thus, recycling processes. The Chemical Index of Alteration (CIA) values are quite homogeneous for the Calabria-Peloritani Arc (mean = 76) and Betic Cordillera sandstones (mean = 55), whereas the Rif Chain sandstones are characterized by CIA values ranging from 54 to 76. The CIW and PIA values are high for all the studied sandstones indicating intense weathering at the source areas. The different values of weathering rates among the studied sandstones may be related to variations of paleoclimatic conditions during the Mesozoic, that further favored recycling processes. Thus, these differences among the studied samples, may be related to an increase in continental palaeoweathering conditions and sediment recycling effects from the Middle Triassic to the earliest Jurassic due to rising humidity. In addition, regional tectonic movements promoted structural changes that allowed sedimentary recycling and subsidence, which in turn caused diagenetic K-metasomatism. These processes could significantly affect the CIW and PIA weathering indices, which likely monitor a cumulative effect, including several cycles of weathering at the source. The source areas are mainly composed of intermediate-felsic rocks with minor, but not negligible, mafic supply, as suggested by provenance proxies.

Perri, F.

2014-03-01

212

Depth and thickness of selected units in Upper Permian, Upper Jurassic, and Lower Cretaceous rocks in southwestern Kansas  

USGS Publications Warehouse

As ground-water reserves decline in the Ogallala aquifer in an area of about 17,400 square miles in 26 counties of southwestern Kansas, sandstone aquifers in underlying Upper Jurassic and Lower and Upper Cretaceous rocks may be developed to supplement or replace the Ogallala as a source of water for some uses. Maps show that depths from land surface to Upper Permian rocks range from 0 at the outcrop to over 2,100 feet, depths to Upper Jurassic rocks ran from 0 at the outcrop to about 2,000 feet, depths to the Cheyenne Sandstone range from about 150 to about 1 ,950 feet, and depths to the Dakota Formation range from 0 at the outcrop to about 1,650 feet. Additional maps show that the thickness of Upper Jurassic rocks, where present, ranges from less than 50 feet to about 250 feet, the thickness of the Cheyenne Sandstone, where present, ranges from about 20 feet to about 250 feet, and the thickness of the Dakota Formation, where present, ranges from about 60 feet to about 460 feet. (USGS)

Kume, Jack; Spinazola, Joseph M.

1984-01-01

213

Geologic map of the Winslow 30’ × 60’ quadrangle, Coconino and Navajo Counties, northern Arizona  

USGS Publications Warehouse

The Winslow 30’ × 60’ quadrangle encompasses approximately 5,018 km2 (1,960 mi2) within Coconino and Navajo Counties of northern Arizona. It is characterized by gently dipping Paleozoic and Mesozoic strata that dip 1° to 2° northeastward in the southwestern part of the quadrangle and become nearly flat-lying in the northeastern part of the quadrangle. In the northeastern part, a shallow Cenozoic erosional basin developed about 20 million years ago, which subsequently was filled with flat-lying Miocene and Pliocene lacustrine sediments of the Bidahochi Formation, as well as associated volcanic rocks of the Hopi Buttes Volcanic Field. The lacustrine sediments and volcanic rocks unconformably overlie Triassic, Jurassic, and Cretaceous strata. Beginning about early Pliocene time, the Little Colorado River and its tributaries began to remove large volumes of Paleozoic and Mesozoic bedrock from the map area. This erosional development has continued through Pleistocene and Holocene time. Fluvial sediments accumulated episodically throughout this erosional cycle, as indicated by isolated Pliocene(?) and Pleistocene Little Colorado River terrace-gravel deposits on Tucker Mesa and Toltec Divide west of Winslow and younger terrace-gravel deposits along the margins of the Little Colorado River Valley. These gravel deposits suggest that the ancestral Little Colorado River and its valley has eroded and migrated northeastward toward its present location and largely parallels the strike of the Chinle Formation. Today, the Little Colorado River meanders within a 5-km (3-mi) wide valley between Winslow and Leupp, where soft strata of the Chinle Formation is mostly covered by an unknown thickness of Holocene flood-plain deposits. In modern times, the Little Colorado River channel has changed its position as much as a 1.5 km (1 mi) during flood events, but for much of the year the channel is a dry river bed. Surficial alluvial and eolian deposits cover extensive parts of the bedrock outcrops over the entire Winslow quadrangle.

Billingsley, George H.; Block, Debra; Redsteer, Margaret Hiza

2013-01-01

214

Late Jurassic weather forecast, Four Corners area: Dry, hot, and partly sunny  

SciTech Connect

Interfingering between members of the Upper Jurassic Morrison Formation and inferences based on their various environments of deposition permit interpretation of a persistent paleoclimate during the Late Jurassic in the Colorado Plateau region. Paleoclimate interpretation is based on evaporites in the Tidwell member, at the base of the Morrison; eolian deposits in the Recapture and Bluff Sandstone members; and saline, alkaline-lake deposits (which indicate high evaporation rates) in the Brushy Basin member at the top of the Morrison. Interfingering of these members with all other members of the Morrison Formation implies that a semiarid to arid climate was likely throughout Morrison time. The semiarid to arid interpretation is consistent with the global climatic zone inferred from the paleogeographic/paleotectonic setting. The Four Corners area during the Late Jurassic was in the middle latitudes of the Northern Hemisphere and thus was affected by prevailing westerly winds. A magmatic arc located several hundred kilometers to the west of the Morrison depositional basin may have caused a broad rain-shadow effect, which contributed to a dry continental climate downwind. A typical Late Jurassic day in the Four Corners area is predicted to have been hot and dry, although seasonally heavy rains probably fed intermittent streams that transported sediments into the region. Explosive eruptions of silicic volcanic ash may have darkened the skies episodically, and thus partly sunny would have been a conservative forecast.

Turner-Peterson, C.E.; Fishman, N.S. (Geological Survey, Denver, CO (USA))

1989-09-01

215

Promise made: The Navajo indian irrigation project and water politics in the American West. Doctoral thesis  

SciTech Connect

According to the 1962 legislation by which the U.S. Congress authorized the Navajo Indian Irrigation Project (NIIP), a federal reclamation project on the Navajo Reservation in northwest New Mexico, it was to bring economic development to the Navajo Tribe in the form of 18,000 jobs on family farms and related enterprises, all in 14 years. The project is today just over half completed, it is a single corporate agribusiness that employs a few hundred Navajo during the peak harvest season, and there are pressures to reduce the size of the project.

Jacobsen, J.E.

1989-01-01

216

Navajo Generating Station and Air Visibility Regulations: Alternatives and Impacts  

SciTech Connect

Pursuant to the Clean Air Act, the U.S. Environmental Protection Agency (EPA) announced in 2009 its intent to issue rules for controlling emissions from Navajo Generating Station that could affect visibility at the Grand Canyon and at several other national parks and wilderness areas. The final rule will conform to what EPA determines is the best available retrofit technology (BART) for the control of haze-causing air pollutants, especially nitrogen oxides. While EPA is ultimately responsible for setting Navajo Generating Station's BART standards in its final rule, it will be the U.S. Department of the Interior's responsibility to manage compliance and the related impacts. This study aims to assist both Interior and EPA by providing an objective assessment of issues relating to the power sector.

Hurlbut, D. J.; Haase, S.; Brinkman, G.; Funk, K.; Gelman, R.; Lantz, E.; Larney, C.; Peterson, D.; Worley, C.; Liebsch, E.

2012-01-01

217

Coping with arsenic-based pesticides on Dine (Navajo) textiles  

NASA Astrophysics Data System (ADS)

Arsenic-based pesticide residues have been detected on Arizona State Museum's (ASM) Dine (Navajo) textile collection using a handheld portable X-ray (pXRF) spectrometer. The removal of this toxic pesticide from historic textiles in museums collections is necessary to reduce potential health risks to Native American communities, museum professionals, and visitors. The research objective was divided into three interconnected stages: (1) empirically calibrate the pXRF instrument for arsenic contaminated cotton and wool textiles; (2) engineer an aqueous washing treatment exploring the effects of time, temperature, agitation, and pH conditions to efficiently remove arsenic from wool textiles while minimizing damage to the structure and properties of the textile; (3) demonstrate the devised aqueous washing treatment method on three historic Navajo textiles known to have arsenic-based pesticide residues. The preliminary results removed 96% of arsenic from a high arsenic concentration (~1000 ppm) textile opposed to minimal change for low arsenic concentration textiles (<100 ppm).

Anderson, Jae R.

218

The Lowell Observatory Navajo-Hopi Astronomy Outreach Program  

NASA Astrophysics Data System (ADS)

We present an overview of the Lowell Observatory Navajo-Hopi Astronomy Outreach Program, which is modeled after the ASP's Project ASTRO (Richter & Fraknoi 1994). Since 1996, our missions have been (1) to use the inherent excitement about the night sky to help teachers get Navajo and Hopi students excited about science and education, and (2) to help teachers of Navajo and Hopi students learn about astronomy and hands-on activities so that they will be better able to incorporate astronomy in their classrooms. Lowell astronomers pair up for a school year with an elementary or middle school (5th-8th grade) teacher and make numerous visits to their teachers' classes, partnering with the educators in leading discussions linked with hands-on activities. Lowell staff also work with educators and amateur astronomers to offer evening star parties that involve the family members of the students as well as the general community. Toward the end of the school year, teachers bring their classes to Lowell Observatory. The classes spend some time exploring the Steele Visitor Center and participating in tours and programs. They also voyage to Lowell's research facility in the evening to observe at two of Lowell's research telescopes. Furthermore, we offer biennial teacher workshops in Flagstaff to provide teachers with tools, curricula materials, and personalized training so that they are able to include astronomy in their classrooms. We also work with tribal educators to incorporate traditional astronomical knowledge. Funding for the program comes from many different sources.

Herrmann, K. A.; Hunter, D. A.; Bosh, A. S.; Johnson, M.; Schindler, K.

2012-08-01

219

25 CFR 161.713 - How will BIA determine the amount of damages to Navajo Partitioned Lands?  

Code of Federal Regulations, 2010 CFR

...DEPARTMENT OF THE INTERIOR LAND AND WATER NAVAJO PARTITIONED LANDS GRAZING PERMITS Trespass ...damages to Navajo Partitioned Lands? (a) BIA will determine...rehabilitation and re-vegetation, loss of future revenue, loss of...

2010-04-01

220

25 CFR 161.713 - How will BIA determine the amount of damages to Navajo Partitioned Lands?  

Code of Federal Regulations, 2012 CFR

...DEPARTMENT OF THE INTERIOR LAND AND WATER NAVAJO PARTITIONED LANDS GRAZING PERMITS Trespass ...damages to Navajo Partitioned Lands? (a) BIA will determine...rehabilitation and re-vegetation, loss of future revenue, loss of...

2012-04-01

221

25 CFR 161.713 - How will BIA determine the amount of damages to Navajo Partitioned Lands?  

Code of Federal Regulations, 2014 CFR

...DEPARTMENT OF THE INTERIOR LAND AND WATER NAVAJO PARTITIONED LANDS GRAZING PERMITS Trespass ...damages to Navajo Partitioned Lands? (a) BIA will determine...rehabilitation and re-vegetation, loss of future revenue, loss of...

2014-04-01

222

25 CFR 161.713 - How will BIA determine the amount of damages to Navajo Partitioned Lands?  

Code of Federal Regulations, 2013 CFR

...DEPARTMENT OF THE INTERIOR LAND AND WATER NAVAJO PARTITIONED LANDS GRAZING PERMITS Trespass ...damages to Navajo Partitioned Lands? (a) BIA will determine...rehabilitation and re-vegetation, loss of future revenue, loss of...

2013-04-01

223

25 CFR 161.713 - How will BIA determine the amount of damages to Navajo Partitioned Lands?  

Code of Federal Regulations, 2011 CFR

...DEPARTMENT OF THE INTERIOR LAND AND WATER NAVAJO PARTITIONED LANDS GRAZING PERMITS Trespass ...damages to Navajo Partitioned Lands? (a) BIA will determine...rehabilitation and re-vegetation, loss of future revenue, loss of...

2011-04-01

224

Sandstone Cliffs in Capitol Reef  

USGS Multimedia Gallery

Sandstone cliffs in Capitol Reef National Park. Capitol Reef is primarily made up of sandstone formations within the Waterpocket Fold, monocline that extends nearly 100 miles. A monocline is a step-like fold in rock strata that can resemble an enormous wrinkle in the earth....

225

Sandstone Cliff in Capitol Reef  

USGS Multimedia Gallery

A sandstone cliff in Capitol Reef National Park. Capitol Reef is primarily made up of sandstone formations within the Waterpocket Fold, monocline that extends nearly 100 miles. A monocline is a step-like fold in rock strata that can resemble an enormous wrinkle in the earth....

226

Sandstone Spire in Capitol Reef  

USGS Multimedia Gallery

A view of a sandstone spire in Capitol Reef National Park. This area, known as the Fruita, is made up of three primary layers. The bottom sandstone layer is known as the Moenkopi Formation and is about 245 million years old. The middle gray-green layer is known as the Chinle Formation and was laid d...

227

Sandstone Monolith in Capitol Reef  

USGS Multimedia Gallery

A sandstone monolith in Capitol Reef National Park. Capitol Reef is primarily made up of sandstone formations within the Waterpocket Fold, monocline that extends nearly 100 miles. A monocline is a step-like fold in rock strata that can resemble an enormous wrinkle in the earth....

228

Diagenesis of Upper Jurassic Norphlet Formation, Mobile and Baldwin Counties and offshore Alabama  

SciTech Connect

The Upper Jurassic Norphlet Formation is an important deep gas reservoir in Mobile and Baldwin Counties and offshore Alabama. The producing reservoir consists of a well-sorted fine-grained subarkose to arkose. Sedimentological studies indicate this unit was deposited on a broad desert plain in environments ranging from eolian dune and interdune to wadi and beach-shoreface. Diagenetic minerals comprise from 5 to 20% of the bulk volume of the sandstone. Porosity ranges from less than 3% to more than 25% and averages around 10%. Most of the porosity consists of hybrid solution-enlarged intergranular and intragranular pores resulting from the dissolution of cements, framework grains, and grain replacements.

Vaughan, R.L. Jr.; Benson, D.J.

1988-09-01

229

Up against Giants: The National Indian Youth Council, the Navajo Nation, and Coal Gasification, 1974-77  

ERIC Educational Resources Information Center

In the spring of 1977, members of the National Indian Youth Council (NIYC), along with the Coalition for Navajo Liberation, barraged the Secretary of the Interior and the chairman of the Navajo Nation with petitions calling for a halt to the proposed construction of several coal gasification plants on the Navajo Reservation in northwestern New…

Shreve, Bradley Glenn

2006-01-01

230

Dine Baa Hane Bi Naaltsoos: Collected Papers from the Seventh through Tenth Navajo Studies Conferences.  

ERIC Educational Resources Information Center

This document contains 29 papers presented at the 7th-10th Navajo Studies Conferences, 1994-97. The papers are arranged in five sections: "Aesthetics: Rugs, Baskets, and Rock Art"; "Doing Anthropology"; "Health"; "Economics"; and "Contact between Cultures." The papers are: "The First Navajo Studies Conference: Reflections by the Cofounders"…

Piper, June-el, Ed.

231

Rhetoric and Resistance: Social Science and Community Schools for Navajos in the 1930s.  

ERIC Educational Resources Information Center

Examines the role of public officials, social scientists, and educational planners in New Deal programs for Navajo Indians. States that resistance to community schools and stock-reduction policies caused the failure of New Deal programs. Concludes that the Navajo experience can help social planners deal more effectively with other social groups.…

James, Thomas

1988-01-01

232

By-Laws of the Parent Advisory Councils Navajo (BIA) Schools.  

ERIC Educational Resources Information Center

To promote maximum Title I services to Navajo students attending the Navajo Area Bureau of Indian Affairs Schools, by-laws for the establishment and operation of a Parent Advisory Council (PAC) have been prepared. Council objectives are to develop good liaison and communication between students' parents and the local school administration; promote…

Bureau of Indian Affairs (Dept. of Interior), Window Rock, AZ.

233

Rural Navajo Youth: A Challenge for Resource Development. Arizona Agricultural Experiment Station Paper No. 284.  

ERIC Educational Resources Information Center

Caught between the Anglo and Navajo worlds, the Navajo youth of Arizona are at home in neither. Material rewards beckon from the Anglo world, but high schools have not provided the educational background to enable the youth to secure those rewards. Instead the schools have merely created in the students a discontent with traditional Reservation…

Christopherson, Victor A.; Dingle, Steven F.

234

The Federal Physician Survey for the Navajo Area: A Predictive Model for Recruitment and Retention.  

ERIC Educational Resources Information Center

The 114 physicians working for the Navajo Area Indian Health Service (IHS) in June 1976 were surveyed to determine what attracted and retained physicians to the Navajo area. Of the 114 questionnaires mailed, 90 were returned. Designed to obtain data on the physician's background, choice of location, and satisfaction with both community and work…

May, Philip A.

235

Bringing Navajo Storytelling Practices into Schools: The Importance of Maintaining Cultural Integrity  

ERIC Educational Resources Information Center

This article examines storytelling practices among Navajos as one example of a non-Western approach to education. The article discusses two stories--one regarding the perspectives of Navajo storytellers concerning the importance of the context of storytelling practices and the other about the research process that led to these perspectives. Eight…

Eder, Donna J.

2007-01-01

236

"Please Read Loose": Intimate Grammars and Unexpected Languages in Contemporary Navajo Literature  

ERIC Educational Resources Information Center

This paper uses Philip Deloria's "Indians in Unexpected Places" as a lens by which to understand the expectations and reviews of Navajo author Blackhorse Mitchell's "Miracle Hill." Written in Navajo English, the book, from an introduction by T. D. Allen to a number of reviews of the book in the popular press, consistently misrecognized the…

Webster, Anthony K.

2011-01-01

237

Jurassic-Neocomian biostratigraphy, North Slope, Alaska  

Microsoft Academic Search

The foraminiferal and palynological biostratigraphy of subsurface Jurassic and Neocomian (Early Cretaceous) age strata from the North Slope were investigated to better define biostratigraphic zone boundaries and to help clarify the correlation of the stratigraphic units in the National Petroleum Reserve in Alaska (NPRA). Through use of micropaleontologic data, eight principal biostratigraphic units have been identified. The Neocomian and Jurassic

M. B. Mickey; H. Haga

1985-01-01

238

Mantophasmatodea now in the Jurassic  

NASA Astrophysics Data System (ADS)

The Mantophasmatodea is the most recently discovered insect order. The fossil records of all other ‘polyneopteran’ orders extend far in the past, but the current absence of pre-Cenozoic fossils of the Mantophasmatodea contradicts a long evolutionary history, which has to be assumed from the morphological distinctness of the group. In this paper, we report the first Mesozoic evidence of a mantophasmatodean from the Middle Jurassic of Daohugou, Inner Mongolia, China. Furthermore, the new fossil shares apomorphic characters with Cenozoic and recent Mantophasmatodea, suggesting a longer evolutionary history of this order.

Huang, Di-Ying; Nel, André; Zompro, Oliver; Waller, Alain

2008-10-01

239

Jurassic Park Institute: Dino Lab  

NSDL National Science Digital Library

Created as a "science-based and educationally focused program," the Jurassic Park Institute (JPI) aims to provide "kids, families, educators and scientists with the ultimate resource for dinosaur learning and fun." As would be expected from a project of Universal Studios, the JPI Dino Lab Web site is packed with cool computer animation and other multimedia features. Visitors to this site become virtual dinosaur paleontologists, interpreting discoveries and solving problems along the way. Educators can register for JPI Dino Lab's free Teacher Resources, which includes lesson plans, assessment tools, and teaching strategy tips. This site is best accessed with a high-speed connection.

240

Sandstones of unexpectedly high diffusibility.  

PubMed

Measurements have been made of diffusion coefficients (D(i)=-mass flux/concentration gradient) using a double reservoir, steady-state method with two tracers, CaBr(2) and amino-G-acid, on intact samples of Triassic red-bed sandstone from northwest England. Diffusibility (D'=D(i)/diffusion coefficient in water) averages 0.124, ranging between 0.075 and 0.215 (porosity 0.1 to 0.24), very similar for the two tracers. Implied tortuosities (actual path length/straight line length) average 1.21 (range 1.06 to 1.47), with constrictivities close to 1. In comparison with limited red-bed sandstone data from elsewhere, these D' values are up to 4 times greater, and tortuosity correspondingly lower. Re-interpretation of formation factor data from previous studies on shallow sandstone samples also from northwest England confirms that diffusibility is significantly higher in these sandstones than others from similar palaeoenvironment/stratigraphic units. The lower tortuosities appear to result from the relatively high permeability, open fabric of the rock, properties likely to be present in shallow sandstone systems used for water supply. It is concluded that diffusion rates may, in some shallow freshwater-containing continental sandstone systems, be significantly greater than is implied by estimates of sandstone diffusibility current in the literature. PMID:21146250

Bashar, Khairul; Tellam, John H

2011-03-25

241

The Law of the People (Dine Bibee Haz'Aannii): A Bicultural Approach to Legal Education for Navajo Students, Volume 2.  

ERIC Educational Resources Information Center

Volume 2 of a 4-volume bilingual bicultural law-related curriculum deals with the evolution of a Navajo legal system. Navajo "law" was referred to by Navajos as "religion", thus Anglos viewed the Navajo as having no "law." Because of the complexity of this topic, it is suggested that the first sections covering this view be read and digested by…

Vicenti, Dan; And Others

242

Jurassic Magmatism, Metamorphism and Basin Development in the Pontides: AN Early Black Sea?  

NASA Astrophysics Data System (ADS)

The Jurassic system in the circum-Black Sea region is characterized by extensive basic magmatism and deposition of thick clastic and volcano-clastic sequences in the Caucasus, Pontides and the Crimea. Acidic to intermediate calc-alkaline granitoidic rocks also crop out in the Central Pontides in Turkey. Recently we also discovered a Jurassic gneiss-dominated metamorphic series in the Central Pontides, which crop out over a large area of 25 km by 5 km and is in close spatial association with the Jurassic magmatic rocks. The metamorphic rocks, known as the Gene Complex, consist of gneiss, gneissic micaschist, migmatite and minor amounts of amphibolite and marble and are cut by granitic veins tens of meters thick. They are unconformably overlain by the Lower Cretaceous sandstones and conglomerates. The critical mineral paragenesis in the gneisses is cordierite + garnet + biotite + quartz + potassium-feldspar. Based on the mineral chemistry of the critical mineral paragenesis, the peak P-T conditions during the metamorphism have been estimated as 720 ± 40 °C temperature and 4 ± 1 kbar pressure. Muscovite and biotite Ar-Ar ages from the gneisses are Late Jurassic (150-140 Ma range). The acidic to intermediate magmatism associated with low pressure - high temperature metamorphism and deposition of over 2000-m-thick clastic and volcanoclastic sedimentary sequences during the Jurassic in the Pontides is best explained by the presence of arc-related basins in the region. However, there is no evidence for continuity between this Paleo-Black Sea basin and the present one, generally considered to be of Early Cretaceous age.

Okay, A. I.; Sunal, G.; Sherlock, S. C.

2011-12-01

243

Petrography and diagenesis of Eagle Mills sandstones, subsurface - Northeast Texas and southwest Arkansas  

SciTech Connect

The Eagle Mills Formation (Triassic-Jurassic) has been penetrated by several deep wells (12,000 to 18,000 ft) in northeast Texas and southwest Arkansas. It consists of green, red, and pink conglomeratic lithic arenites and fine- to coarse-grained feldspathic arenites, interbedded with red and greenish gray shales and siltstones. Lithic arenites contain basalt, chert, quartzite, and dolomite rock fragments; plagioclase is the predominant feldspar. All Eagle Mills sandstones have low textural and mineralogic maturities. Eagle Mills red beds and associated intrusive igneous rocks (diabase and basalt dikes and sills) represent the fillings of grabens or rift basins that actively subsided during deposition (in alluvial, fluvial-deltaic, and lacustrine paleoenvironments). Eagle Mills lithic and feldspathic sandstones have undergone a complex diagenetic history, including chlorite cementation (pore linings and pore fillings), compaction, quartz and feldspar overgrowths, dolomite cementation, chloritization and albitization of detrital feldspars, local dissolution of framework grains (igneous lithics and feldspars), precipitation of kaolinite, late Fe-calcite cementation, and saddle dolomite formation. Cement mineralogies are strongly correlative with lithofacies. Lithic sandstones contain the highest frequency of chlorite cements, whereas feldspathic sandstones are preferentially cemented with carbonates and anhydrite; quartz and feldspar overgrowths are ubiquitous. The suite of authigenic minerals in Eagle Mills sandstones records progressive burial into a deep, high-temperature (120-150C), semiclosed, diagenetic regime.

Dawson, W.C.; Callender, C.A. (Texaco, Houston, TX (United States))

1991-03-01

244

Diagenesis of deeply buried Eagle Mills sandstones. Implications for paleo-fluid migration and porosity development  

SciTech Connect

Eagle Mills strata (Triassic-Jurassic) unconformably overlie the Paleozoic basement complex and thus, form the basal sedimentary unit within the Gulf Coast basin. Jurassic-aged basaltic dikes and sills have intruded Eagle Mills strata. These sedimentary and igneous rocks are the earliest record of Gulf of Mexico rifting. Deeply buried (15,000 to 18,000 ft.) Eagle Mills sandstone have subarkosic and sublithic modal compositions. These sandstones exhibit evidence of a complex and prolonged diagnetic history, including: early chlorite cementation; early quartz and feldspar overgrowths; early calcite and dolomite cementation; dissolution of framework grains and early carbonate cements; kaolinite precipitation; late ferroan carbonate cementation; albitization; late chlorite and anhydrite replacement; saddle dolomite cementation; and pyritization. Pyrobitumens coat early chlorite rim cements indicating that most diagenesis post-dated hydrocarbon migration. Secondary porosity development coincided with a later burial dissolution event. The Eagle Mills paragenetic sequence records progressive burial into a high-temperature diagenetic regime where thermochemical sulfate reduction was the dominant process. Marked shifts in paleo-water chemistry are recorded by the Eagle Mills diagenetic sequence. Pervasive dissolution of detrital feldspars in some Eagle Mills sandstones provides unequivocal petrographic evidence for deep-seated sourcing of diagenetic fluids, which migrated along faults, and contributed to the diagenesis of overlying Mesozoic strata. These petrographic analyses support interpretations of geochemical/fluid-flux data for the Mesozoic Gulf Coast basin.

Dawson, W.C. [Texaco EPTD, Houston, TX (United States)

1995-10-01

245

Strategies for assessing EarlyMiddle (PliensbachianAalenian) Jurassic  

E-print Network

cyclostratigraphy of the Jurassic Period. First, Jurassic geochronology is not well constrained, due to a generalStrategies for assessing Early­Middle (Pliensbachian­Aalenian) Jurassic cyclochronologies By Linda in stratigraphic constraints. These problems are particularly troublesome in the Early to Middle Jurassic cyclic

246

Cardiovascular disease in Navajo Indians with type 2 diabetes.  

PubMed Central

Rates of both type 2 diabetes and cardiovascular disease have risen sharply in recent years among Navajo Indians, the largest reservation-based American Indian tribe, but the association between the two conditions is not entirely clear. Rates of cardiovascular disease and some possible associations in several hundred diabetic and non-diabetic Navajos were estimated. Nearly one-third (30.9 percent) of those with diabetes had formal diagnoses of cardiovascular disease--25.3 percent had heart disease, 4.4 percent had cerebrovascular disease, and 4.1 percent had peripheral vascular disease. (The percentages exceed the total because some people had more than one diagnosis. Age-adjusted rates were 5.2 times those of nondiabetics for heart disease, 10.2 times for cerebrovascular disease, and 6.8 times for peripheral vascular disease. Accentuation of risk was most marked in young diabetics and in female diabetics. Hypertensive diabetics had a twofold increase in heart disease and more than a fivefold increase in cerebral and peripheral vascular disease over nonhypertensive diabetics. Age, blood pressure, cholesterol levels, and albumenuria were independent risk factors for cardiovascular disease. Triglyceride levels or body weight were not. Male sex and diabetes duration were independent risk factors for cerebral and peripheral vascular disease but not for heart disease. In view of the impressive segregation of cardiovascular disease in the diabetic Navajo population, the prevention of diabetes through population-based health promotion seems basic to its containment. Over the short term, vigorous treatment of hypertension in subjects who are already diabetic is mandatory. PMID:7838949

Hoy, W; Light, A; Megill, D

1995-01-01

247

Provenance changes for sandstones from the Sierra de los Cuarzos (central Mexico): the possible record of a terrane accretion  

NASA Astrophysics Data System (ADS)

The Guerrero terrane is composed of Late Jurassic-Early Cretaceous arc successions exposed along the western Pacific margin of Mexico. Several lines of evidence indicate that the Guerrero terrane represents the Mexican leading-edge of the North American plate, which was drifted in the paleo-Pacific domain during Late Jurassic-Early Cretaceous back-arc spreading, and subsequently accreted back to the Mexican continental core before the Albian. In this paper, we present new stratigraphic data and a detailed provenance analysis of sandstones from the Sierra de Los Cuarzos area, which is located in central Mexico, ~50 km to the east of the Guerrero terrane suture belt. In the Sierra de Los Cuarzos is exposed a Mesozoic succession composed of: 1) quartz-rich turbidites grading upward to 2) calcareous slump deposits, which are overlain by 3) volcaniclastic sandstone and scarce conglomerate hosting 20 cm- to 100 m-wide blocks and slabs of basalt. Sandstone provenance and paleocurrent marks indicate that turbidites and slumps deposits were fed by sources from the Mexican continental core. Similar Late Jurassic-Early Cretaceous turbidites and calcareous slump deposits are exposed in the Sierra de Guanajuato, ~50 km to the west of the Sierra de Los Cuarzos area, and are preliminarily correlated with the lower units (1 and 2) of the study area. On the other hand, provenance analysis indicates that volcaniclastic sandstones from unit 3 were principally fed by the arc successions exposed in the Guerrero terrane. The drastic change in provenance of sandstones from the Sierra de los Cuarzos suggests a complex depositional history, characterized by the contribution of distinct supplying sources during the infilling of the basin. In this paper, it is explored the possibility of a syn-tectonic origin for the volcaniclastic rocks of the Sierra de Los Cuarzos, related to the accretion of the Guerrero terrane to the Mexican continental core.

Palacios García, N. B.; Martini, M.

2012-04-01

248

Irrigation management with remote sensing. [Navajo Indian Irrigation Project  

NASA Technical Reports Server (NTRS)

Two visible/near IR hand held radiometers and a hand held thermoradiometer were used along with soil moisture and lysimetric measurements in a study of soil moisture distribution in afalfa fields on the Navajo Indian Irrigation Project near farmington, New Mexico. Radiances from irrigated plots were measured and converted to reflectances. Surface soil water contents (o cm to 4 cm) were determined gravimetrically on samples collected at the same time as the spectral measurements. The relationship between the spectral measurements and the crop coefficient were evaluated to demonstrate potential for using spectral measurement to estimate crop coefficient.

Harlan, C.; Heilman, J. L.; Moore, D.; Myers, V. (principal investigators)

1982-01-01

249

Mask of the Black God: The Pleiades in Navajo Cosmology  

NSDL National Science Digital Library

This interdisciplinary case study will help students learn about celestial coordinates and constellations in the context of a Navajo legend. Learners will have the opportunity to determine celestial coordinates, locate the sun on the celestial sphere for any day of the year, and describe the location of a given constellation in relation to other prominent nearby constellations. The lesson could be used in high school or undergraduate coursework. The case study and teaching notes may be downloaded in PDF format. The site also includes a section for instructor feedback where general comments may be read and contributed.

Schulz, Teresa M.

250

Sandstone Formations in Capitol Reef  

USGS Multimedia Gallery

Capitol Reef is primarily made up of sandstone formations within the Waterpocket Fold, monocline that extends nearly 100 miles. A monocline is a step-like fold in rock strata that can resemble an enormous wrinkle in the earth....

251

A Jurassic mammal from South America.  

PubMed

The Jurassic period is an important stage in early mammalian evolution, as it saw the first diversification of this group, leading to the stem lineages of monotremes and modern therian mammals. However, the fossil record of Jurassic mammals is extremely poor, particularly in the southern continents. Jurassic mammals from Gondwanaland are so far only known from Tanzania and Madagascar, and from trackway evidence from Argentina. Here we report a Jurassic mammal represented by a dentary, which is the first, to our knowledge, from South America. The tiny fossil from the Middle to Late Jurassic of Patagonia is a representative of the recently termed Australosphenida, a group of mammals from Gondwanaland that evolved tribosphenic molars convergently to the Northern Hemisphere Tribosphenida, and probably gave rise to the monotremes. Together with other mammalian evidence from the Southern Hemisphere, the discovery of this new mammal indicates that the Australosphenida had diversified and were widespread in Gondwanaland well before the end of the Jurassic, and that mammalian faunas from the Southern Hemisphere already showed a marked distinction from their northern counterparts by the Middle to Late Jurassic. PMID:11894091

Rauhut, Oliver W M; Martin, Thomas; Ortiz-Jaureguizar, Edgardo; Puerta, Pablo

2002-03-14

252

Tectonic insights from an Upper Jurassic Lower Cretaceous stretched-clast conglomerate, Caborca Altar region, Sonora, Mexico  

NASA Astrophysics Data System (ADS)

The ranges directly northeast of Caborca and Altar preserve a 2000+ m-thick folded section of the Altar Formation, composed of ductilely deformed Upper Jurassic-Lower Cretaceous polymict conglomerate, sandstone, mudstone, and andesite. Stratigraphic relationships indicate that this section, which accumulated in a 60 km-long northwest-trending basin, is broadly correlative with the Glance Conglomerate. Coarse (boulder-cobble) detritus in the lower part of the section was shed from prominent highlands consisting of the Middle Jurassic magmatic arc and the Neoproterozoic-Paleozoic miogeocline. In the pebbly upper part of the section, abundant sandstone, mudstone, lacustrine(?) carbonate, and felsic tuff interstratified with andesite flows, and breccias record lower-energy depositional conditions interrupted locally by volcanism. By the time of Bisbee Sea incursion into northwestern Mexico, the Jurassic arc source had disappeared and the miogeoclinal source was topographically subdued. The Lower Cretaceous Morita Formation, which conformably overlies the Altar Formation along a gradational contact, records marine transgression that accompanied regional subsidence. Significant northeast-southwest contraction affected the Altar Formation, Bisbee Group, and Upper Cretaceous strata between 71 and 51 Ma. Characteristics of this Laramide event include asymmetric, northeast-verging folds and thrusts accompanied by penetrative southwest-dipping stretched-clast foliation or cleavage and greenschist-facies metamorphism. Mid-Tertiary normal faults overprint the compressional structures such that deeper levels of the stratigraphy are juxtaposed against shallower levels, and axial planes of major range-scale folds are rotated about horizontal axes relative to one another.

Nourse, J. A.

2001-10-01

253

Carbohydrate biofuels II: The need and the potential for rootfuel in the Navajo Nation  

SciTech Connect

Over 80% of rural Navajos and about two-thirds of all Navajos use scarce woodfuel and low-grade coal for home heating half the year, with coal used mainly as a nighttime adjunct. Serious health problems arise because stoves are old and leak smoke and carbon monoxide. The impacts are gender-biased to women and small children. Respiratory disease is a major cause of Navajo mortality and unusually high admissions to Navajo Indian Health Service hospitals. A 1990 study at a Navajo hospital showed that Navajo children under two years of age from homes with woodstoves are nearly five times more likely to contract acute lower respiratory tract infections than children from homes with no stove. Correctives include improved stoves and fuels. Our previous studies on clean-burning starchy/cellulosic {open_quotes}rootfuels{close_quotes} in Latin America, Africa, and Asia are applicable. We discuss our preliminary work on the Navajo reservation, the current status of household stoves and stovefuels, the health impacts of woodsmoke and coalsmoke from old, faulty stoves, the conditions for growing rootfuel on the reservation, and policy and strategy for coping with the problem.

Shultz, E.B.; Jr.; Bragg, W.G. [Enable International, Wheaton, IL (United States); Whittier, J. [NEOS Corp., Lakewood, CO (United States)] [and others

1995-11-01

254

Navajo Coal Combustion and Respiratory Health Near Shiprock, New Mexico  

PubMed Central

Indoor air pollution has been identified as a major risk factor for acute and chronic respiratory diseases throughout the world. In the sovereign Navajo Nation, an American Indian reservation located in the Four Corners area of the USA, people burn coal in their homes for heat. To explore whether/how indoor coal combustion might contribute to poor respiratory health of residents, this study examined respiratory health data, identified household risk factors such as fuel and stove type and use, analyzed samples of locally used coal, and measured and characterized fine particulate airborne matter inside selected homes. In twenty-five percent of homes surveyed coal was burned in stoves not designed for that fuel, and indoor air quality was frequently found to be of a level to raise concerns. The average winter 24-hour PM2.5 concentration in 20 homes was 36.0??g/m3. This is the first time that PM2.5 has been quantified and characterized inside Navajo reservation residents' homes. PMID:20671946

Bunnell, Joseph E.; Garcia, Linda V.; Furst, Jill M.; Lerch, Harry; Olea, Ricardo A.; Suitt, Stephen E.; Kolker, Allan

2010-01-01

255

Jurassic sequence stratigraphy of the eastern Gulf Coastal Plain: Applications to hydrocarbon exploration  

SciTech Connect

Based on regional stratigraphic and sedimentologic data, three unconformity-bounded depositional sequences associated with cycles of relative sea-level change and coastal onlap are recognized for Jurassic strata in the eastern Gulf Coastal Plain area. These sequences are designated, in ascending order, the LZAGC (Lower Zuni A Gulf Coast)-3.1, the LZAGC-4.1, and the LZAGC-4.2 sequences and include Callovian through Kimmeridgian Stage strata. An understanding of the relationship of Jurassic reservoirs to sequence stratigraphy can serve as an aid to hydrocarbon exploration in the eastern gulf area. The most extensive and productive Jurassic hydrocarbon reservoirs in the study area occur within the progradational, regressive highstand deposits of the LZAGC-3.1 and LZAGC-4.1 depositional sequences. For example, the majority of Norphlet sandstone reservoirs in the onshore and offshore Alabama area are interpreted to have accumulated in eolian dune, interdune, and wadi (fluvial) depositional environments, which occurred in association with the highstand regressive system of the LZAGC-3.1 sequence. The most important Smackover reservoirs generally consist of partially to completely dolomitized ooid and peloid packstones and grainstones in the upper portion of the unit. These reservoirs occur in subtidal to supratidal, shoaling-upward carbonate mudstone to grainstone cycles in the highstand regressive system of the LZAGC-4.1 sequence. In addition, minor reservoirs that are discontinuous and not well developed are associated with the shelf margin and transgressive systems of the LZAGC-4.1.

Tew, B.H.; Mancini, E.A.; Mink, R.M. (Geological Survey of Alabama, Tuscaloosa (United States))

1991-03-01

256

Conglomeratic fan deltas and submarine fans of the Jurassic Laberge Group, Whitehorse Trough, Yukon Territory, Canada: fore-arc sedimentation and unroofing of a volcanic island arc complex  

Microsoft Academic Search

The Lower and Middle Jurassic Laberge Group consists of conglomerates, sandstone turbidites and shales that were deposited within a deep-water fore-arc trough. The conglomerate of the Laberge Group accounts for most of the preserved basin-fill within the Whitehorse Trough, and was derived from exhumed plutons, comprising multiple intrusives and extrusives of varying composition, that formed an island arc terrane in

John R. Dickie; Frances J. Hein

1995-01-01

257

Regional porosity trends of the Upper Jurassic Norphlet Formation in southwestern Alabama and vicinity, with comparisons to formations of other basins  

Microsoft Academic Search

Sandstone porosity of the Upper Jurassic Norphlet Formation in southwestern Alabama and vicinity decreases systematically as depth and thermal maturity increase over a wide range. Median porosity is about 25% where equivalent vitrinite reflectance (R[sub o]) is slightly over 0.7% in the northern part of the study area (Clarke County, Mississippi). Median porosity is reduced to 8% where R[sub o

J. W. Schmoker; C. J. Schenk

1994-01-01

258

Lower Cretaceous and Upper Jurassic oil reservoirs of the updip basement structure play: Southwest Alabama  

SciTech Connect

Exploration for Lower Cretaceous and Upper Jurassic reservoirs associated with updip basement structures currently is the most active exploratory oil play in Alabama. High initial flow rates, on the order of hundreds to thousands of barrels of oil per day, are commonly encountered at depths between 8,200 and 14,500 feet. Fifty-one fields have been established and 25 million barrels of oil have been produced from these fields developed in Lower Cretaceous Hosston and Upper Jurassic Haynesville, Smackover, and Norphlet reservoirs. Production from Smackover carbonates began at Toxey field in 1967 and from Haynesville sandstones at Frisco City field in 1986. As of September 1994, Smackover wells averaged 88 barrels of oil per day and Haynesville wells averaged 284 barrels of oil per day. In 1994, production was established in the Norphlet at North Excel field and in the Hosston at Pleasant Home field. Reservoirs in the updip basement structure play cluster in three distinct areas; (1) a western area on the Choctaw ridge complex, (2) a central area on the Conecuh ridge complex, and (3) an eastern area in the Conecuh embayment. Reservoir lithologies include Smackover limestones and dolostones and Hosston, Haynesville, Smackover, and Norphlet sandstones. Hydrocarbon traps are structural or combination traps where reservoirs occur on the flanks or over the crests of basement palohighs. An understanding of the complex reservoir properties and trap relationships is the key to successful discovery and development of Lower Cretaceous and Upper Jurassic oil reservoirs of the updip basement structure play of southwest Alabama.

Mink, R.M.; Mancini, E.A. [Geological Survey of Alabama, Tuscaloosa, AL (United States)

1995-10-01

259

Jurassic exploration trends of East Texas  

SciTech Connect

This article deals with exploration and production from the Jurassic reservoirs of East Texas. The paper discussed the trapping mechanisms, structural configurations, lithologies and stratigraphic relationships. The major formations presented are the Smackover and the Haynesville (Cotton Valley).

Presly, M.W.; Reed, C.H.

1984-09-01

260

World petroleum systems with Jurassic source rocks  

SciTech Connect

Fourteen petroleum systems with Upper Jurassic source rocks contain one quarter of the world's discovered oil and gas. Eleven other systems with Lower and Middle Jurassic source rocks presently have a minor but significant amount of discovered oil and gas. The purpose of this article is to review the systems geologically, describe their location in space and time on a continental scale, estimate their relative petroleum system recovery efficiencies, and outline the effect their essential elements and processes have on their petroleum plumbing.

Klemme, H.D. (Geo Basins Ltd., Bondville, VT (United States))

1993-11-08

261

Jurassic-Neocomian biostratigraphy, North Slope, Alaska  

SciTech Connect

The foraminiferal and palynological biostratigraphy of subsurface Jurassic and Neocomian (Early Cretaceous) age strata from the North Slope were investigated to better define biostratigraphic zone boundaries and to help clarify the correlation of the stratigraphic units in the National Petroleum Reserve in Alaska (NPRA). Through use of micropaleontologic data, eight principal biostratigraphic units have been identified. The Neocomian and Jurassic strata have each been subdivided into four main units.

Mickey, M.B.; Haga, H.

1985-04-01

262

The Lower Cretaceous Chouf Sandstone of Lebanon: is it a syn-rift clastic sequence?  

NASA Astrophysics Data System (ADS)

The lowermost unit of the Cretaceous succession onshore Lebanon is a widespread prominent sandstone formation traditionally known as the "Grès de Base". The Chouf Sandstone is one of the most distinctive geologic units in Lebanon and is extensively quarried as building sand. The formation commonly consists of a brown to white sandstone with associated claystones, shales, locally volcanics and lignites. Based on outcrop samples taken in the central and northern parts of Mount Lebanon the petrographical composition of the typical Chouf Sandstone is dominated by monocrystalline quartz (85-95%) indicating a well-sorted sandstone. Sedimentological observations suggest deposition of the formation was typically in fluvial, coastal plain and deltaic environments. The Chouf Sandstone is variable in thickness, ranging from a few metres to 300 m. In certain areas rapid lateral thickness changes have been reported which may reflect a paleo-topography or syn-depositional block faulting. Similar thickness variations in the underlying Upper Jurassic formations might be interpreted as the result of syn-rift normal faulting. In order to test the syn-rift nature of the Chouf Sandstone, modern high-resolution satellite data sets (with ~ 0.75 m horizontal and 4 m vertical resolution) were used to derive thickness data points for the Chouf Sandstone in NW Lebanon. One important reason to use high-resolution satellite data for onshore Lebanon is the general lack of structural measurements on the existing vintage geologic maps. In lieu of these basic data, the common surface point method was used to derive this information in a consistent manner across the study area. First results obtained by remote sensing techniques do reveal local variations in the thickness of the Chouf Sandstone, on order of tens to hundreds of meters. These isopach variations in a map-view sense are interpreted to be the result of deposition in individual extensional half-grabens in a much larger overall basin. As the overlying Lower Cretaceous neritic carbonate formations do not exhibit these thickness variations, the syn-rift character of the Chouf Sandstone appears to be a reasonable interpretation at this preliminary stage of this ongoing study.

Hatzenbichler, Georg; Bauer, Harald; Grasemann, Bernhard; Tari, Gabor; Nader, Fadi H.; Church, Jonathan; Schneider, Dave

2013-04-01

263

A quantitative model of ground-water flow during formation of tabular sandstone uranium deposits  

USGS Publications Warehouse

Presents a quantitative simulation of regional groundwater flow during uranium deposition in the Westwater Canyon Member and Jackpile Sandstone Member of the Upper Jurassic Morrison Formation in the San Juan basin. Topographic slope, shoreline position, and density contrasts in the lake and pore fluids controlled the directions of flow and recharge-discharge areas. The most important results for uranium ore deposit formation are that regional groundwater discharged throughout the basin, regional discharge was concentrated along the shore line or playa margin, flow was dominantly gravity driven, and compaction dewatering was negligible. A strong association is found between the tabular sandstone uranium deposits and major inferred zones of mixed local and regional groundwater discharge. -from Author

Sanford, R.F.

1994-01-01

264

The Late Jurassic Oblique Collisional Orogen of SW Japan. New Structural Data and Synthesis  

NASA Astrophysics Data System (ADS)

The structural configuration of SW Japan mainly reflects a late Jurassic-early Cretaceous orogeny. The region is divided into an inner belt and an outer belt, on the Japan sea and Pacific ocean sides respectively, by a strike-slip fault, the Median Tectonic Line (MTL). Both consist of a series of stacked nappes. The inner belt is divided into a Jurassic olistostrome known as the Tanba zone and a hinterland area comprising continental Triassic-Jurassic sediments. The Tanba zone is sliced into two units: a lower one with late Jurassic matrix and Triassic-early Jurassic radiolarite olistoliths, tectonically overthrust by an upper unit comprising an olistostrome with middle Jurassic matrix and blocks which include late Paleozoic limestone, basic lava, and radiolarite. The Tanba zone is overthrust by a Paleozoic nappe complex derived from the hinterland. The basal sole of the nappe corresponds to a peculiar unit called the ultra-Tanba zone. In the Chugoku area, the hinterland is divided into an upper nappe: the Oga nappe, formed by Permo-Carboniferous limestone and Permian clastic rocks and a lower one: the Sangun-Maizuru nappe, formed by Paleozoic high pressure (HP) metamorphics (the Sangun schists), the Permian Maizuru olistostrome, and the dismembered Paleozoic Yakuno ophiolites. In the northern part of SW Japan, the Tanba zone is in faulted contact with the circum-Hida and the Hida zones. The former is interpreted as the equivalent of the Oga and Sangun-Maizuru nappes of the Chugoku domain crushed by post Cretaceous tectonics. The latter consists of Paleozoic high temperature (HT) metamorphic rocks and late Triassic-early Jurassic granite, locally mylonitized and covered by early Jurassic sandstone. The outer belt is formed by a superficial nappe similar to the Tanba zone thrust upon a "deep domain" characterized by a synmetamorphic ductile deformation. The "deep domain" is divided into a lower unit, the Oboke unit formed by continental derived arenites and a Green Schist nappe consisting of oceanic sediments and resedimented ophiolites.The Green Schist nappe overthrusts the Oboke unit under synmetamorphic conditions with an eastward displacement. The two belts are separated by the Ryoke zone which corresponds to the southern part of the Tanba zone affected by a Cretaceous HT metamorphism and sharply cut by the MTL. A geodynamic model is proposed for the Jurassic orogeny of SW Japan assuming that the evolution of the inner and outer belts are linked. In the Late Triassic-Early Jurassic SW Japan is an active plate margin. The upper plate or South China block consisted of the hinterland and the Tanba belt, a forearc basin; the lower plate consisted of an oceanic area and the South Japan continent. The basic mechanism of the orogeny is ascribed to the oblique subduction and collision of the South Japan continent.

Faure, Michel; Caridroit, Martial; Charvet, Jacques

1986-12-01

265

Solar membrane distillation: desalination for the Navajo Nation.  

PubMed

Provision of clean water is among the most serious, long-term challenges in the world. To an ever increasing degree, sustainable water supply depends on the utilization of water of impaired initial quality. This is particularly true in developing nations and in water-stressed areas such as the American Southwest. One clear example is the Navajo Nation. The reservation covers 27,000 square miles, mainly in northeastern Arizona. Low population density coupled with water scarcity and impairment makes provision of clean water particularly challenging. The Navajos rely primarily on ground water, which is often present in deep aquifers or of brackish quality. Commonly, reverse osmosis (RO) is chosen to desalinate brackish ground water, since RO costs are competitive with those of thermal desalination, even for seawater applications. However, both conventional thermal distillation and RO are energy intensive, complex processes that discourage decentralized or rural implementation. In addition, both technologies demand technical experience for operation and maintenance, and are susceptible to scaling and fouling unless extensive feed pretreatment is employed. Membrane distillation (MD), driven by vapor pressure gradients, can potentially overcome many of these drawbacks. MD can operate using low-grade, sub-boiling sources of heat and does not require extensive operational experience. This presentation discusses a project on the Navajo Nation, Arizona (Native American tribal lands) that is designed to investigate and deploy an autonomous (off-grid) system to pump and treat brackish groundwater using solar energy. ?ench-scale, hollow fiber MD experiment results showed permeate water fluxes from 21 L/m2·d can be achieved with transmembrane temperature differences between 40 and 80?C. Tests run with various feed salt concentrations indicate that the permeate flux decreases only about 25% as the concentration increases from 0 to 14% (w/w), which is four times seawater salt concentration. The quality of the permeate water remains constant at about 1 mg/L regardless of the changes in the influent salt concentration. A nine-month MD field trial, using hollow fiber membranes and completely off-the-shelf components demonstrated that a scaled-up solar-driven MD system was practical and economically viable. Based on these results, a pilot scale unit will be constructed and deployed on the tribal lands. PMID:24552961

Karanikola, Vasiliki; Corral, Andrea F; Mette, Patrick; Jiang, Hua; Arnoldand, Robert G; Ela, Wendell P

2014-01-01

266

New Early Jurassic Tetrapod Assemblages Constrain Triassic-Jurassic Tetrapod Extinction Event  

Microsoft Academic Search

The discovery of the first definitively correlated earliest Jurassic (200 million years before present) tetrapod assemblage (Fundy basin, Newark Supergroup, Nova Scotia) allows reevaluation of the duration of the Triassic-Jurassic tetrapod extinction event. Present are tritheledont and mammal-like reptiles, prosauropod, theropod, and ornithischian dinosaurs, protosuchian and sphenosuchian crocodylomorphs, sphenodontids, and hybodont, semionotid, and palaeonisciform fishes. All of the families are

P. E. Olsen; N. H. Shubin; M. H. Anders

1987-01-01

267

78 FR 36716 - Approval of Air Quality Implementation Plans; Navajo Nation; Regional Haze Requirements for...  

Federal Register 2010, 2011, 2012, 2013, 2014

...EPA provided a three-month period for public comments, to close on May 6, 2013. The Navajo Nation, Gila River Indian Community, and other affected stakeholders requested a 90-day extension of the comment period to allow time for...

2013-06-19

268

The Navajo Nation has collected hydroclimate data throughout the Nation lands but the system has been  

E-print Network

collection stations, interviewed staff, analyzed the NNDWR hydroclimate data, evaluated instrumentation and exchange of data with outside agencies. PROJECT FACT SHEET Assessment of Navajo Nation Hydroclimate Network monitoring ef- forts. · · · · · · KEY SCIENCE FINDINGS Data analyses and interviews confirmed that hydro

Fay, Noah

269

Melding Research on the Navajo Volcanic Field into Undergraduate Curriculum to Promote Scientific Literacy  

NSDL National Science Digital Library

David Gonzales, Fort Lewis College Summary Mafic dike in the Navajo volcanic field exposed near Newcomb, New Mexico. Details This module highlights the curricular design and outcomes of undergraduate research in ...

David Gonzales

270

Breast Cancer Education for Navajo Women: a Pilot Study Evaluating a Culturally Relevant Video  

Microsoft Academic Search

This pilot study evaluated a culturally specific video designed to teach Navajo women about breast cancer treatment options.\\u000a Fourteen Navajo women diagnosed with breast cancer and 26 healthcare providers participated in a mixed-method evaluation that\\u000a documented their perceptions immediately and 6 months after viewing the video. After initial viewing, women reported reduced\\u000a anxiety about treatment and interest in support groups. Six

Priscilla R. Sanderson; Nicolette I. Teufel-Shone; Julie A. Baldwin; Nellie Sandoval; Frances Robinson

2010-01-01

271

Trace fossil evidence from the Adigrat Sandstone for an Ordovician glaciation in Eritrea, NE Africa  

NASA Astrophysics Data System (ADS)

Trace fossils are described here from the Adigrat Sandstone formation of hitherto uncertain Palaeozoic-Mesozoic age in south-central Eritrea. The formation is subdivided into a lower unit, the Adi MaEkheno Member, and an upper informal unit, Member 2. The formation was deposited on the locally mudcracked top of the glacigenic Edaga Arbi Beds, suggesting that these two rock units were formed in a very short time interval. The Adi MaEkheno Member and the lower part of Member 2 contain trace fossils Arthrophycus alleghaniensis (Harlan), Arthrophycus ?brongniartii (Harlan), Didymaulichnus lyelli (Rouault), Palaeophycus tubularis Hall, Taenidium isp., thin winding ridges, winding ridges and furrows, simple cylinders, and 'stellate' forms. A. alleghaniensis is distinctively of Ordovician-Silurian (?Early Devonian) age. The trace fossil association belongs to the Cruziana ichnofacies that indicates a shallow marine environment between the normal and storm wave bases. The trace fossil data and stratigraphic relationships indicate that the Adigrat Sandstone formation and the Edaga Arbi Beds in Eritrea are Ordovician-Silurian in age. The Edaga Arbi Beds are correlated with other Upper Ordovician (Hirnantian) glacial units in northern Africa and the Arabian Peninsula, lending these beds the status of a marker unit in the Lower Palaeozoic stratigraphy of the Horn of Africa. The Jurassic "Adigrat Sandstone" in central-west and eastern Ethiopia cannot be correlated with the Adigrat Sandstone formation in its type area and in Eritrea.

Kumpulainen, R. A.; Uchman, A.; Woldehaimanot, B.; Kreuser, T.; Ghirmay, S.

2006-08-01

272

Diagenesis and reservoir potential of volcanogenic sandstones—Cretaceous of the Surat Basin, Australia  

NASA Astrophysics Data System (ADS)

The Mesozoic Surat Basin is an important hydrocarbon-producing basin in Australia. The principal productive reservoirs there are the quartzose sandstones of Early Jurassic age. Although oil and gas shows have been reported from the Cretaceous part of the succession it does not contain any known economic hydrocarbons. The sandstones of the Cretaceous section are characterized by abundant volcanogenic detritus in the form of rock fragments and feldspars. These compositionally immature sandstones are not regarded as favourable exploration targets for hydrocarbons because of their lithic nature, their shallow burial depths, and hence the low thermal maturity of the intercalated mudrocks which might have constituted hydrocarbon source rocks. However, petrographic and petrophysical examinations show that significant primary and diagenetic secondary dissolution porosity and permeability exist in some of these stratigraphic units which under certain circumstances could be the host for hydrocarbons and may become the future exploration targets. Shallow burial depth and early interstitial precipitation of various authigenic minerals have retarded compaction and thereby contributed to the preservation of moderate to good primary porosity. Additionally, flushing by CO 2-charged meteoric water after the inception of the Great Artesian Basin in the Tertiary has created significant amounts of secondary dissolution porosity in these sandstones.

Hawlader, H. M.

1990-03-01

273

A subsurface study of the Denkman sandstone member, Norphlet Formation, hatters Pond field, Mobile County, Alabama  

SciTech Connect

Hatters Pond field is in east-central Mobile County in southwestern Alabama and it produces from both the Norphlet and Smackover formations. The structural trap involves salt movement along the west side of the Mobile Fault System that resulted in a faulted salt anticline. The Norphlet Formation of southwestern Alabama consists of red to gray siltstone and pinkish to gray sandstone with conglomerate layers. Three facies have been distinguished within the Norphlet Formation: a lower shale, a red siltstone sequence, and an upper quartzose unit. The thickness of the formation ranges from a feather edge to more than 800 ft (234.8 m) in southwestern Alabama. The Upper Jurassic Denkman Sandstone Member of the Norphlet Formation at Hatters Pond field is a medium- to fine-grained, well-sorted arkosic sandstone between the underlying Norphlet redbed lithofacies and the carbonates of the overlying Smackover Formation. Here, the Denkman Member can be subdivided into a massive upper unit and a low- to high-angle cross-stratified lower unit. The sandstones are quartz-rich with a high percentage of feldspars. The majority of the feldspar grains observed are potassium feldspar. Microcline is usually less altered when compared with other types of feldspar grains. The major types of feldspar replacement include illitization, hematitization, dolomitization, chloritization, calcitization, vacuolization, and anhydritization. Carbonate replacement of feldspars is very abundant, mostly by ferroan dolomite. Rock fragments are not abundant in the Denkman Member, although there is good evidence of a metamorphic/volcanic source area. The sandstones are cemented by dolomite, calcite, anhydrite, and quartz and feldspar overgrowths. The lower Denkman unit is slightly more porous than the upper Denkman unit. The pore-lining authigenic clay, illite, greatly reduces permeability and porosity in these sandstones.

Young, L.M.; Anderson, E.G.; Baria, L.R. (Northeast Louisiana Univ., Monroe (USA)); Higginbotham, R.S.

1990-09-01

274

Diagenesis of fluvial sands in Norphlet Formation (Upper Jurassic), Escambia County, Alabama  

SciTech Connect

The Upper Jurassic Norphlet Formation is an important hydrocarbon reservoir in Baldwin and Mobile Counties and offshore in Mobile Bay, Alabama. The formation is not productive in the Little Escambia Creek field, Escambia County, but underlies the productive Smackover Formation at a depth of approximately 15,500 ft (4725 m). The Norphlet sandstones examined in cores from two drill holes are largely fluvial in origin and consist of moderately to well-sorted, very fine to coarse-grained feldspathic sandstones extensively altered by a complex sequence of diagenetic reactions. Visible evidence of chemical and mechanical compaction is relatively minor in the sandstones. Paucity of compaction suggests that extensive early cementation by anhydrite and/or calcite reduced compaction; these cements were subsequently removed by migrating fluids. Porosity, both intergranular and intragranular, is generally well developed. Intergranular pores are due primarily to partial to complete dissolution of cements and mineral grains, especially feldspar. Intragranular pores are largely the result of partial leaching of rock fragments and of microporosity formed by precipitation of clay minerals in earlier dissolution pores.

Keighin, C.W.; Schenk, C.J.

1989-03-01

275

Navajo Generating Station and Clean-Energy Alternatives: Options for Renewables  

SciTech Connect

In January 2012, the National Renewable Energy Laboratory delivered to the Department of the Interior the first part of a study on Navajo Generating Station (Navajo GS) and the likely impacts of BART compliance options. That document establishes a comprehensive baseline for the analysis of clean energy alternatives, and their ability to achieve benefits similar to those that Navajo GS currently provides. This analysis is a supplement to NREL's January 2012 study. It provides a high level examination of several clean energy alternatives, based on the previous analysis. Each has particular characteristics affecting its relevance as an alternative to Navajo GS. It is assumed that the development of any alternative resource (or portfolio of resources) to replace all or a portion of Navajo GS would occur at the end of a staged transition plan designed to reduce economic disruption. We assume that replacing the federal government's 24.3% share of Navajo GS would be a cooperative responsibility of both the U.S. Bureau of Reclamation (USBR) and the Central Arizona Water Conservation District (CAWCD).

Hurlbut, D. J.; Haase, S.; Turchi, C. S.; Burman, K.

2012-06-01

276

Healthy Gardens/Healthy Lives: Navajo perceptions of growing food locally to prevent diabetes and cancer  

PubMed Central

Poor access to nutritious foods, departure from traditional diets, and reduced physical activity are associated with a rise in type-2 diabetes and certain types of cancers among the Navajo. Diabetes in particular is of concern because of its increased prevalence among Navajo youth. Gardening can successfully address issues of poor availability of fruits and vegetables and offer many other social and health benefits. Our assessment aimed to determine Navajo attitudes about gardening and health in San Juan County, New Mexico. We conducted seven focus groups (including 31 people) to assess knowledge and attitudes related to gardening, and uncover barriers and facilitators to participation in a garden project. Each group session was moderated by two Navajo students. Transcripts revealed that many Navajo are aware of adverse health issues, predominantly obesity and diabetes, which occur on the reservation. Participants expressed a preference for educational approaches that incorporated cultural traditions, respect for elders, use of visual aids and experiential learning. Several social and agronomic barriers to gardening were also mentioned. Results suggested a broad interest in promoting gardening especially to reduce the risk of diabetes with the added value of enhancing social capital in Navajo communities. PMID:23855020

Beresford, Shirley A.A.; Ornelas, India; Topaha, Carmelita; Becenti, Tonia; Thomas, Dustin; Vela, Jaime G.

2013-01-01

277

Healthy gardens/healthy lives: Navajo perceptions of growing food locally to prevent diabetes and cancer.  

PubMed

Poor access to nutritious foods, departure from traditional diets, and reduced physical activity are associated with a rise in type 2 diabetes and certain types of cancers among the Navajo. Diabetes in particular is of concern because of its increased prevalence among Navajo youth. Gardening can successfully address issues of poor availability of fruits and vegetables and offer many other social and health benefits. Our assessment aimed to determine Navajo attitudes about gardening and health in San Juan County, New Mexico. We conducted seven focus groups (including 31 people) to assess knowledge and attitudes related to gardening and uncover barriers and facilitators to participation in a garden project. Each group session was moderated by two Navajo students. Transcripts revealed that many Navajo are aware of adverse health issues that occur on the reservation, predominantly obesity and diabetes. Participants expressed a preference for educational approaches that incorporated cultural traditions, respect for elders, use of visual aids, and experiential learning. Several social and agronomic barriers to gardening were also mentioned. Results suggested a broad interest in promoting gardening especially to reduce the risk of diabetes with the added value of enhancing social capital in Navajo communities. PMID:23855020

Lombard, Kevin A; Beresford, Shirley A A; Ornelas, India J; Topaha, Carmelita; Becenti, Tonia; Thomas, Dustin; Vela, Jaime G

2014-03-01

278

Environments of deposition and diagenesis of the Jurassic Upper Smackover Formation in the Lincoln Parish area, Louisiana  

E-print Network

of Petroleum Geologists Bulletin. UPPER SMACKOVER LITHOFACIES ~A+ AC K 0 VE R ALA. I '':. ~s T E X A S I Ml SS. MIXED FACIES -SANDS EVAPORITES, CARBONATES PELAGIC MUD FACIES TL . '9 OOLITE ? PELLET FACIES EU PELLET -MUD FACIES SANDSTONES SANDY...- G NI T SCHULER FM. 0 TONGUE O V) M K D P TONGU UPPER MBR OF BUCKNER F UPPER K ON y) N 0 El M BR. 0 LOWE R M BR. O (0 Ch CC D LOU ANN F M. c I EAGLE MILLS FM. Figure 2. Generalized Triassic and Jurassic stratigraphic...

Palko, Gregory Jonathan

1980-01-01

279

Bedrock aquifers in the lower Dirty Devil River basin area, Utah, with special emphasis on the Navajo sandstone  

USGS Publications Warehouse

The lower Dirty Devil River basin area in southeastern Utah has an area of about 4,300 square miles (11,140 square kilometers) and ranges in altitude from about 3,700 to more than 11,000 feet (1,130 to 3,350 meters) above mean sea level. Precipitation, the main source of water in the area, ranges from slightly less than 6 inches (152 millimeters) per year in the lowlands to more than 30 inches per year (762 millimeters) in the Henry Mountains and along the western boundary.

Hood, J.W.; Danielson, T.W.

1981-01-01

280

Bedrock aquifers in the northern San Rafael Swell area, Utah, with special emphasis on the Navajo Sandstone  

USGS Publications Warehouse

The northern San Rafael Swell area in southeastern Utah includes about 2,880 square miles (7,460 square kilometers) and ranges in altitude from about 3,290 to 7,921 feet (1,195 to 2,414 meters). Precipitation, the main source of water in the area, ranges from slightly less than 6 inches (152 millimeters) to slightly more than 12 inches (305 millimeters).

Hood, J.W.; Patterson, D.J.

1984-01-01

281

LANDFORMS GENERATED BY WIND EROSION OF NAVAJO SANDSTONE OUTCROPS AT THE WAVE (COLORADO PLATEAU, UTAH / ARIZONA BORDER)  

E-print Network

that are undercut by wind abrasion. In the photos above and to the left, note the microbially darkened rock surface Bedforms: Direct Evidence for Eolian Abrasion Arizona Utah wind wind wind wind wind wind The Wave "The Wave not play an obvious role in formation of the troughs. Resistant beds form "thresholds" on the floors

Nebraska-Lincoln, University of

282

Regional porosity trends of the Upper Jurassic Norphlet Formation in southwestern Alabama and vicinity, with comparisons to formations of other basins  

USGS Publications Warehouse

Sandstone porosity of the Upper Jurassic Norphlet Formation decreases systematically as depth and thermal maturity increase over a wide range. Median porosity is about 25% where equivalent vitrinite reflectance (Ro) is slightly over 0.7% in the northern part of the study area (Clarke County, Mississippi). Median porosity is reduced to 8% where Ro approaches 2.7% in the southern part of the study area. Based on the comparisons at similar Ro levels, median (50th-percentile) Norphlet porosity exceeds porosities of "typical' sandstones in other basins by more than a factor of two throughout the study area. Even the lower (10th-percentile) Norphlet porosities are higher than median porosities of sandstones in general. -from Authors

Schmoker, J.W.; Schenk, C.J.

1994-01-01

283

The Lower Jurassic ornithischian dinosaur Heterodontosaurus tucki Crompton & Charig, 1962  

E-print Network

The Lower Jurassic ornithischian dinosaur Heterodontosaurus tucki Crompton & Charig, 1962: cranial 27 August 2010 The cranial anatomy of the Lower Jurassic ornithischian dinosaur Heterodontosaurus commonly seen in basal archosaurs and saurischian dinosaurs). Evidence for tooth replacement (which has

284

Environment of deposition of the upper Jurassic "Gray" sandstones, Terryville field, Lincoln Parish, Louisiana  

E-print Network

black shale facies, and a deep marine trace fossil assemblage indicate a basinal environment of deposition. ACKNOWLEDGEMENTS I would like to thank Dr. Robert Berg, Chairman of my committee, for providing the topic and research funds for this study... (Walper et al. , 1979) There are two members in the Smackover (Fig. 2). The lower member is composed of dark, unfossiliferous, pyritic, lime mudstones, argillaceous limestones and calcareous shales which were deposited in a quiet, toxic, basinal en...

Mani, Philip Charles

1983-01-01

285

TriassicJurassic boundary events: Problems, progress, possibilities 1. Problems  

E-print Network

As for most geological period boundaries, the Triassic­Jurassic (T­J) transition, 200 million years agoEditorial Triassic­Jurassic boundary events: Problems, progress, possibilities 1. Problems to reconstruct past events, a physical record of their passing is essential. Here again the Triassic­Jurassic

McRoberts, Christopher A.

286

Late Jurassic salamandroid from western Liaoning, China  

PubMed Central

A Jurassic salamander, Beiyanerpeton jianpingensis (gen. et sp. nov.), from a recently found site in western Liaoning Province, China is the earliest known record of Salamandroidea. As a Late Jurassic record of the group, it extends the range of the clade by ~40 Ma. The Late Jurassic taxon is neotenic and represented by exceptionally preserved specimens, including fully articulated cranial and postcranial skeletons and bony gill structures close to the cheek region. The fossil beds, consisting of dark-brown volcanic ash shales of the Upper Jurassic Tiaojishan (Lanqi) Formation (Oxfordian), underlie trachyandesite rocks that have yielded a SHRIMP zircon U-Pb date of 157 ± 3 Ma. The fossiliferous beds are substantially older than the Jehol Group, including the Yixian Formation (40Ar/39Ar dates of 122–129 Ma), but slightly younger than the Middle Jurassic Daohugou horizon (40Ar/39Ar date of 164 ± 4 Ma). The early fossil taxon shares with extant salamandroids derived character states, including: separated nasals lacking a midline contact, angular fused to the prearticular in the lower jaw, and double-headed ribs on the presacral vertebrae. In contrast to extant salamandroids, however, the salamander shows a discrete and tooth-bearing palatine, and unequivocally nonpedicellate and monocuspid marginal teeth in large and presumably mature individuals. The finding provides insights into the evolution of key characters of salamanders, and also provides direct evidence supporting the hypothesis that the split between Cryptobranchoidea and Salamandroidea had taken placed before the Late Jurassic Oxfordian time. In this aspect, both paleontological and molecular data now come to agree. PMID:22411790

Gao, Ke-Qin; Shubin, Neil H.

2012-01-01

287

Evaluating Reading Materials in Navajo: Report of a Teachers' Conference (Gallup, New Mexico, April 28-29, 1972). Navajo Reading Study Progress Report No. 18.  

ERIC Educational Resources Information Center

Elementary-grade reading materials produced in the Navajo language were evaluated at a teacher's conference held in Gallup, New Mexico, on April 28-29, 1972. Participants, mostly teachers, at the conference numbered approximately 45. The 5 texts evaluated were "Mosilgai" (School Cat), "Jasper," Pabii Doo Masi" (Puppy and Cat), "Da'iida" (Eat), and…

Gradman, Harry L.; Young, Robert W.

288

Log interpretation of shaly sandstones  

E-print Network

dispersed clays with the gamma-ray readings from 50 to 90 zv API units, measured water saturations from 60 to 90%, and the resistivities fzom 2. 0 to 3. 6 ohm m. The sandstones from the other well contained dominantly laminated clays with gamma... Intracoastal Land ()2 well, Bayou Cholpe field. Relationship between thin ? section fraction of shale and the calculated volume of shale from the gamma ray using the Dresser Atlas consolidated rock formula, The dashed curve represents the predicted gamma...

Baker, Joel Foster

1987-01-01

289

Tidal influence within Pennsylvanian sandstones  

SciTech Connect

Within Pennsylvanian-age strata of the Illinois basin, large-scale linear sand bodies have been previously interpreted as fluvial and deltaic in origin. Nonetheless, analyses of fine-scale sedimentology and bed forms within such sandstones and the associated shales indicate that tidal processes greatly influenced the depositional environments within such lithofacies. Recent work on Mid-Continent Pennsylvanian-age sandstones indicates the occurrence of similar depositional environments. Based upon the pervasive tidal influence observed within such strata, environmental analogs other than fluvial and deltaic bear consideration. In general, tidally influenced estuarine models seem particularly appropriate. Within such settings, the changeover from a fluvially dominated deposystem to tidally influenced estuary occurs during transgressive phases. Despite the tidal influence that can be interpreted from the sedimentology, the strata contain few, if any, marine indicators because of the low salinities that occurred during deposition. Ongoing work in the Mid-Continent indicates that Morrowan, Atokan, Desmoinesian, Missourian, and Virgilian sands share a number of similarities with the tidally influenced environments delineated in the Illinois basin studies. Thus a tidal/estuarine interpretation might be a generalizable model for many Pennsylvanian sandstones. In addition, enhanced understanding of the siliciclastic parts of Mid-Continent cyclothems provides a more useful framework for documentation of carbonate/siliciclastic interrelationships. Oscillations of carbonate/siliciclastic environments may be more readily explainable by climatic cycles rather than by traditionally popular depth-related facies models.

Archer, A.W. (Kansas State Univ., Manhattan (United States))

1991-08-01

290

Livestock impacts for management of reclaimed land at Navajo Mine: The decision-making process  

SciTech Connect

Livestock grazing is the post-mining use for reclaimed land at Navajo Mine, a large surface coal mine on the Navajo Nation in northwest New Mexico. The Navajo Mine Grazing Management Program (GMP) uses holistic management on approximately 2,083 ha of reclaimed land to plan for final liability release and return of the land to the Navajo Nation, and to minimize the potential for post-release liability. The GMP began in 1991 to establish that livestock grazing on the reclaimed land is sustainable. Assuming that sustainability requires alternatives to conventional land management practices, the GMP created a Management Team consisting of company staff, local, Navajo Nation, and Federal government officials, and technical advisors. Community members contributed to the formation of a holistic goal for the GMP that articulates their values and their desire for sustainable grazing. Major decisions (e.g., artificial insemination, water supply, supplemental feed) are tested against the goal. Biological changes in the land and the grazing animals are monitored daily to provide early feedback to managers, and annually to document the results of grazing. To date, the land has shown resilience to grazing and the animals have generally prospered. Community participation in the GMP and public statements of support by local officials indicate that the GMP`s strategy is likely to succeed.

Estrada, O.J. [BHP World Minerals Navajo Mine, Fruitland, NM (United States); Grogan, S. [Resource Planning & Management Inc., Albuquerque, NM (United States); Gadzia, K.L. [Resource Management Services, Bernalillo, NM (United States)

1997-12-31

291

A Feasibility Study to Evaluate Wind Energy Potential on the Navajo Nation  

SciTech Connect

The project, A Feasibility Study to Evaluate Wind Energy Potential on the Navajo Nation, is funded under a solicitation issued by the U.S. Department of Energy Tribal Energy Program. Funding provided by the grant allowed the Navajo Nation to measure wind potential at two sites, one located within the boundaries of the Navajo Nation and the other off-reservation during the project period (September 5, 2005 - September 30, 2009). The recipient for the grant award is the Navajo Tribal Utility Authority (NTUA). The grant allowed the Navajo Nation and NTUA manage the wind feasibility from initial site selection through the decision-making process to commit to a site for wind generation development. The grant activities help to develop human capacity at NTUA and help NTUA to engage in renewable energy generation activities, including not only wind but also solar and biomass. The final report also includes information about development activities regarding the sited included in the grant-funded feasibility study.

Terry Battiest

2012-11-30

292

Jurassic stratigraphy of the Wiggins Arch, Mississippi  

SciTech Connect

Mobil and Shell jointly explored the Wiggins arch area in southern Mississippi from 1985 to 1991. The effort concentrated on the Jurassic Norphlet and Smackover formations. Two wells were drilled into Paleozoic crystalline rocks and one well into the Pine Hill formation. Two of these wells were located on the southern side of the Wiggins arch and provide significant data for interpreting Jurassic stratigraphy. The Mobil No. 1 U.S.A. well encountered a complete Jurassic section, but with some significantly different facies than those encountered by wells to the north. A granite wash section is the equivalent to the Frisco City formation previously only found 100 mi to the north-northeast. All 300 ft of Smackover is crystalline dolomite. The Norphlet section is entirely granite wash. The Pine Hill anhydrite is unusually thick and interpreted to be equivalent to the Louann Salt. Correlations to other wells on the Wiggins arch, particularly the Conoco No. 1 Higgins, indicate that the Jurassic can be divided into three transgressive events separated by the Norphlet/Pine Hill and Frisco City/Buckner regressive events.

Rhodes, J.A.; Maxwell, G.B. (Mobil Oil Company, Houston, TX (United States))

1993-09-01

293

Jurassic evolution of the Tien-Shan  

SciTech Connect

Complex studies led to identification of three stages in Jurassic deposits. The stages reflect development periods of the studied deposits. Each stage is represented by a paleogeographic map that indicates the evolution of ancient landforms in the Tien-Shan region in time and space.

Bebeshev, I.I. [Geological Institute, Moscow (Russian Federation)

1994-09-01

294

Discovering the "-Ologies" on the Jurassic Coast  

ERIC Educational Resources Information Center

The Jurassic Coast is Britain's only natural World Heritage site, a tangible time-line that takes one through 185 million years of history in 95 miles of coast. It provides individuals with a world-famous educational resource and an unrivalled outdoor classroom that has played a key role in the study of earth sciences. The author is keen to ignite…

Peacock, Alan

2007-01-01

295

Dinosaur dynamics in the Jurassic Era  

NASA Astrophysics Data System (ADS)

Dinosaurs were fascinating animals and elicit much excitement in the classroom. Analysis of fossilized dinosaur trackways permits one to estimate the locomotion speeds and accelerations of these extinct beasts. Such analysis allows one to apply Newton's laws of motion to examples from the Jurassic Era.

Lee, Scott

2010-04-01

296

New early Jurassic tetrapod assemblages constrain Triassic-Jurassic tetrapod extinction event.  

PubMed

The discovery of the first definitively correlated earliest Jurassic (200 million years before present) tetrapod assemblage (Fundy basin, Newark Supergroup, Nova Scotia) allows reevaluation of the duration of the Triassic-Jurassic tetrapod extinction event. Present are tritheledont and mammal-like reptiles, prosauropod, theropod, and ornithischian dinosaurs, protosuchian and sphenosuchian crocodylomorphs, sphenodontids, and hybodont, semionotid, and palaeonisciform fishes. All of the families are known from Late Triassic and Jurassic strata from elsewhere; however, pollen and spore, radiometric, and geochemical correlation indicate an early Hettangian age for these assemblages. Because all "typical Triassic" forms are absent from these assemblages, most Triassic-Jurassic tetrapod extinctions occurred before this time and without the introduction of new families. As was previously suggested by studies of marine invertebrates, this pattern is consistent with a global extinction event at the Triassic-Jurassic boundary. The Manicouagan impact structure of Quebec provides dates broadly compatible with the Triassic-Jurassic boundary and, following the impact theory of mass extinctions, may be implicated in the cause. PMID:3616622

Olsen, P E; Shubin, N H; Anders, M H

1987-08-28

297

South and North Barents Triassic-Jurassic total petroleum system of the Russian offshore Arctic  

USGS Publications Warehouse

One major gas-prone petroleum system characterizes the sparsely explored South and North Barents Basin Provinces of the Russian Arctic in the eastern Barents Sea. More than 13 billion barrels of oil equivalent (79 trillion cubic feet of gas) known ultimately recoverable gas reserves in seven fields were sourced from Triassic marine and continental shales and stored in Jurassic (97%) and Triassic (3%) marine and continental sandstone reservoir rocks. The basins contain 18-20 kilometers of pre-Upper Permian carbonate and post-Upper Permian siliciclastic sedimentary fill. Late Permian-Triassic(?) rifting and subsidence resulted in the deposition of as much as 9 kilometers of Triassic strata, locally injected with sills. Rapidly buried Lower Triassic source rocks generated hydrocarbons as early as Late Triassic into stratigraphic traps and structural closures that were modified periodically. Thermal cooling and deformation associated with Cenozoic uplift impacted seal integrity and generation processes, modified traps, and caused gas expansion and remigration.

Lindquist, Sandra J.

1999-01-01

298

Navajo birth outcomes in the Shiprock uranium mining area  

SciTech Connect

The role of environmental radiation in the etiology of birth defects, stillbirths, and other adverse outcomes of pregnancy was evaluated for 13,329 Navajos born at the Public Health Service/Indian Health Service Hospital in the Shiprock, NM, uranium mining area (1964-1981). More than 320 kinds of defective congenital conditions were abstracted from hospital records. Using a nested case-control design, families of 266 pairs of index and control births were interviewed. The only statistically significant association between uranium operations and unfavorable birth outcome was identified with the mother living near tailings or mine dumps. Among the fathers who worked in the mines, those of the index cases had histories of more years of work exposure but not necessarily greater gonadal dosage of radiation. Also, birth defects increased significantly when either parent worked in the Shiprock electronics assembly plant. Overall, the associations between adverse pregnancy outcome and exposure to radiation were weak and must be interpreted with caution with respect to implying a biogenetic basis.

Shields, L.M.; Wiese, W.H.; Skipper, B.J.; Charley, B.; Benally, L. (Navajo Community College, Shiprock, NM (United States))

1992-11-01

299

Bird-Like Anatomy, Posture, and Behavior Revealed by an Early Jurassic Theropod Dinosaur Resting Trace  

PubMed Central

Background Fossil tracks made by non-avian theropod dinosaurs commonly reflect the habitual bipedal stance retained in living birds. Only rarely-captured behaviors, such as crouching, might create impressions made by the hands. Such tracks provide valuable information concerning the often poorly understood functional morphology of the early theropod forelimb. Methodology/Principal Findings Here we describe a well-preserved theropod trackway in a Lower Jurassic (?198 million-year-old) lacustrine beach sandstone in the Whitmore Point Member of the Moenave Formation in southwestern Utah. The trackway consists of prints of typical morphology, intermittent tail drags and, unusually, traces made by the animal resting on the substrate in a posture very similar to modern birds. The resting trace includes symmetrical pes impressions and well-defined impressions made by both hands, the tail, and the ischial callosity. Conclusions/Significance The manus impressions corroborate that early theropods, like later birds, held their palms facing medially, in contrast to manus prints previously attributed to theropods that have forward-pointing digits. Both the symmetrical resting posture and the medially-facing palms therefore evolved by the Early Jurassic, much earlier in the theropod lineage than previously recognized, and may characterize all theropods. PMID:19259260

Milner, Andrew R. C.; Harris, Jerald D.; Lockley, Martin G.; Kirkland, James I.; Matthews, Neffra A.

2009-01-01

300

Norphlet formation (Upper Jurassic) of southwestern and offshore Alabama: environments of deposition and petroleum geology  

SciTech Connect

Upper Jurassic Norphlet sediments in southwestern and offshore Alabama accumulated under arid climatic conditions. The Appalachian Mountains of the eastern United States extended into southwestern Alabama to provide a barrier for air and water circulation during the deposition of the Norphlet Formation. These mountains produced topographic conditions that contributed to the arid climate, and they affected sedimentation. Norphlet paleogeography in southwestern Alabama was dominated by a broad desert plain, rimmed to the north and east by the Appalachians and to the south by a developing shallow sea. The desert plain extended westward into eastern and central Mississippi. Norphlet hydrocarbon potential in southwestern and offshore Alabama is excellent; six oil and gas fields already have been established. Petroleum traps discovered to date are primarily structural traps involving salt anticlines, faulted salt anticlines, and extensional fault traps associated with salt movement. Reservoir rocks consist primarily of quartz-rich sandstones that are eolian, wadi, and marine in origin. Porosity is principally secondary (dissolution) with some intergranular porosity. Smackover algal carbonate mudstones were probably the source for the Norphlet hydrocarbons. Jurassic oil generation and migration probably were initiated in the Early Cretaceous.

Mancini, E.A.; Bearden, B.L.; Mink, R.M.; Wilkerson, R.P.

1985-06-01

301

Recoverable natural gas reserves from Jurassic Norphlet Formation, Alabama coastal waters  

SciTech Connect

To date, 11 Norphlet gas fields have been established in offshore Alabama. These fields are part of a deep Jurassic gas trend that extends across southern Mississippi and Alabama into the Gulf of Mexico. Recoverable gas reserves of 4.9-8.1 tcf are estimated for the Norphlet Formation in Alabama's coastal waters. Proven gas reserves are estimated to be 3.7-4.6 tcf and potential reserves are estimated to be 1.2-3.5 tcf. The natural gas is trapped in a series of generally east-west-trending salt anticlines. The mechanism of structure formation appears to be salt flowage that has formed broad, low-relief anticlines, most of which are faulted, and many of which are related to small-scale growth faults. Salt movement is the critical factor in the formation of these petroleum traps. The primary Norphlet reservoir lithofacies are eolian dune and interdune sandstones that range in thickness from 140 to over 600 ft in Alabama's coastal waters. Gas pay can exceed 280 ft in thickness. Porosity is principally secondary, developed as a result of decementation and grain dissolution. Jurassic Smackover algal carbonate mudstones were the main source for the Norphlet hydrocarbons. The seal for the gas is the nonpermeable upper portion of the Norphlet Formation. The overlying lower Smackover carbonates are also nonpermeable and may serve as part of the seal.

Mancini, E.A.; Mink, R.M.; Bearden, B.L.; Hamilton, R.P.

1987-09-01

302

Didactyl Tracks of Paravian Theropods (Maniraptora) from the ?Middle Jurassic of Africa  

PubMed Central

Background A new dinosaur tracksite from ?Middle Jurassic sediments of the Irhazer Group on the plains of Agadez (Rep. Niger, northwest Africa) revealed extraordinarily well preserved didactyl tracks of a digitigrade bipedal trackmaker. The distinct morphology of the pes imprints indicates a theropod trackmaker from a paravian maniraptoran closely related to birds. Methodology/Principal Findings The early age and the morphological traits of the tracks allow for description of the new ichnotaxon Paravipus didactyloides. A total of 120 tracks are assigned to 5 individual trackways. The ‘medium-sized’ tracks with an average footprint length of 27.5 cm and footprint width of 23.1 cm are deeply imprinted into the track bearing sandstone. Conclusions/Significance A comparison with other didactyl tracks gives new insights into the foot morphology of advanced maniraptoran theropods and contributes to knowledge of their evolutionary history. The new ichnotaxon takes an important position in the ichnological fossil record of Gondwana and the mid-Jurassic biota worldwide, because it is among the earliest known records of paravian maniraptorans and of didactyl theropod tracks from Africa. PMID:21339816

Mudroch, Alexander; Richter, Ute; Joger, Ulrich; Kosma, Ralf; Idé, Oumarou; Maga, Abdoulaye

2011-01-01

303

Bird-like anatomy, posture, and behavior revealed by an early jurassic theropod dinosaur resting trace  

USGS Publications Warehouse

Background: Fossil tracks made by non-avian theropod dinosaurs commonly reflect the habitual bipedal stance retained in living birds. Only rarely-captured behaviors, such as crouching, might create impressions made by the hands. Such tracks provide valuable information concerning the often poorly understood functional morphology of the early theropod forelimb. Methodology/Principal Findings: Here we describe a well-preserved theropod trackway in a Lower Jurassic (???198 millionyear- old) lacustrine beach sandstone in the Whitmore Point Member of the Moenave Formation in southwestern Utah. The trackway consists of prints of typical morphology, intermittent tail drags and, unusually, traces made by the animal resting on the substrate in a posture very similar to modern birds. The resting trace includes symmetrical pes impressions and well-defined impressions made by both hands, the tail, and the ischial callosity. Conclusions/Significance: The manus impressions corroborate that early theropods, like later birds, held their palms facing medially, in contrast to manus prints previously attributed to theropods that have forward-pointing digits. Both the symmetrical resting posture and the medially-facing palms therefore evolved by the Early Jurassic, much earlier in the theropod lineage than previously recognized, and may characterize all theropods.

Milner, A.R.C.; Harris, J.D.; Lockley, M.G.; Kirkland, J.I.; Matthews, N.A.

2009-01-01

304

Sequence stratigraphy of middle and upper Jurassic strata of Southwestern Alabama  

SciTech Connect

Middle and Upper Jurassic systems tracts of southwestern Alabama differ from those of the western Gulf rim, showing: (1) profound influence of antecedent topography; (2) low early subsidence rates; and (3) greater clastic influx from adjacent uplands. Werner Anhydrite and Louann Salt represent the earliest marine incursion onto the Gulf rim following initial rifting; they onlap upper Paleozoic basement and garben-filling Eagle Mills red beds. Because basin-wide evaporative drawdowns overprint even higher order eustatic sea level changes, transgressive systems tracts (TST) and highstand systems tracts (HST) are indistinguishable. Anhydrite and shale caps accumulated via interstratal halite dissolution. Oxfordian Norphlet siliciclastics form a continental lowstand systems tract as illustrated by abrupt contact with underlying marine evaporites without intervening progradational marginal marine facies. Marine-reworked uppermost Norphlet sandstone marks the base of a subsequent TST, which includes overstepping lower Smackover lithofacies (laminated mudstone, algal-laminated mudstone, and pellet wackestone). The upper Smackover HST is characterized by formation of rimmed shelves upon which algal mounds and aggrading ooid grainstone parasequences accumulated. Shallow lagoonal carbonate and evaporite saltern deposition occurred behind ooid shoals; fine-grained siliciclastics accumulated in updip areas. Equivalents of Smackover A, Smackover B, Bossier, and Gilmer sequences are largely masked by influx of Haynesville and Cotton Valley continental clastics. Lack of biostratigraphic data, a consequence of restricted fauna, precludes useful age assignments for these sequences in Alabama. Middle and Upper Jurassic systems tracts of southwestern Alabama are regionally atypical and cannot serve as a model for Gulf-wide sequences.

Wade, W.J.; Moore, C.H. Jr. (Louisiana State Univ., Baton Rouge, LA (United States))

1993-09-01

305

Depositional setting of the Jurassic Haynesville seismic sequence in the Apalachicola Basin, northeastern Gulf of Mexico  

SciTech Connect

Seismic and well data from the northeastern Gulf of Mexico were used to define the seismic stratigraphy, geologic history, and depositional setting of the Jurassic (Kimmeridgian) Haynesville sequence in the Apalachicola basin. The data show that Haynesville clastic sedimentation updip was coeval with Haynesville carbonate deposition downdip. The regional Jurassic seismic stratigraphic framework includes, in ascending order, the Louann Salt Norphlet-Smackover, Haynesville, and Cotton Valley sequences. In the vicinity of Destin dome, wells have penetrated Haynesville sandstones, shales, and anhydrites. These clastics correlate with low amplitude, low-continuity reflections that characterize the Haynesville over a broad area updip. Similar reflections within the overlying (Tithonian-earliest Berriasian) Cotton Valley clastic sequence make seismic definition of the top Haynesville sequence boundary difficult updip. As Haynesville clastics are replaced by carbonates downdip, a high amplitude reflection marks the top of the sequence. Haynesville carbonates conformably overlie (Oxfordian) Smackover carbonates in the basin center, and the lower sequence boundary cannot be defined where disrupted by growth faults associated with early movement of the (Callovian ) Louann Salt. Sigmoid clinoforms document Haynesville shelf margin development Seismic facies also include oblique clinoforms that prograde eastward into the basin from the Southern Platform and Middle Ground Arch. No wells penetrate this facies. Mapping of the seismic facies and correlation with well data suggest a depositional setting for the Haynesville sequence in which influx of terrigenous clastics probably derived from adjacent land areas to the north and northeast filled a broad lagoon behind a carbonate shelf margin.

Dobson, L.M.; Buffler, R.T. (Univ. of Texas, Austin (USA))

1990-05-01

306

Diabetes on the Navajo nation: what role can gardening and agriculture extension play to reduce it?  

PubMed

Diabetes has emerged as a serious health problem in the Navajo nation, the largest Indigenous tribe in the US. Persons with diabetes are at greater risk for developing other diseases such as cardiovascular disease. Navajos with diabetes almost certainly face a diminished quality of life if their diabetes is not managed properly. Aside from genetics, the incidence of diabetes is highly correlated with income, poor diet, and limited physical exercise. A review of the literature also implicates dietary shifts initiated by historical events and contemporary trends. Numerous studies have shown that moderate consumption of fruits and vegetables, combined with exercise, reduces the risk of or delays the onset of many diseases including diabetes. As part of a larger holistic approach, home and community garden projects have successfully addressed nutrition and food security issues on a grassroots scale. The Navajos have a tradition of farming and therefore expanding Navajo diabetes interventions to include the promotion of community and home gardens provides multiple opportunities. The benefits of these actions include: (i) a variety of nutritious food grown locally; (ii) physical activity attained through the act of daily gardening tasks; (iii) positive income garnered in terms of savings in food otherwise purchased at stores and excess produce canned, or if desired, sold at a farmer's market or trading post; and (iv) positive mental outlook through a combined sense of accomplishment at harvest time, bonding with the earth, and spiritual growth. The objectives of this article were to review the development of diabetes on the Navajo nation though historical and contemporary literature, to provide insight into the role of diet and exercise in the progression of the disease, and to offer cases and suggestions in the role that home and community gardening can play in diabetes reduction. A concluding discussion proposes a multidisciplinary approach to tackling diabetes on the Navajo nation involving public health officials, nutritionists, and horticultural extension agents that could also be applied internationally in similar multicultural, semi-arid climates. PMID:17044752

Lombard, Kevin A; Forster-Cox, Susan; Smeal, Dan; O'Neill, Mick K

2006-01-01

307

Assessments of aquifer sensitivity on Navajo Nation and adjacent lands and ground-water vulnerability to pesticide contamination on the Navajo Indian Irrigation Project, Arizona, New Mexico, and Utah  

USGS Publications Warehouse

The U.S. Environmental Protection Agency requested that the Navajo Nation conduct an assessment of aquifer sensitivity on Navajo Nation lands and an assessment of ground-water vulnerability to pesticide contamination on the Navajo Indian Irrigation Project. Navajo Nation lands include about 17,000 square miles in northeastern Arizona, northwestern New Mexico, and southeastern Utah. The Navajo Indian Irrigation Project in northwestern New Mexico is the largest area of agriculture on the Navajo Nation. The Navajo Indian Irrigation Project began operation in 1976; presently (2001) about 62,000 acres are available for irrigated agriculture. Numerous pesticides have been used on the Navajo Indian Irrigation Project during its operation. Aquifer sensitivity is defined by the U.S. Environmental Protection Agency as 'The relative ease with which a contaminant [pesticide] applied on or near a land surface can migrate to the aquifer of interest. Aquifer sensitivity is a function of the intrinsic characteristics of the geologic material in question, any underlying saturated materials, and the overlying unsaturated zone. Sensitivity is not dependent on agronomic practices or pesticide characteristics.' Ground-water vulnerability is defined by the U.S. Environmental Protection Agency as 'The relative ease with which a contaminant [pesticide] applied on or near a land surface can migrate to the aquifer of interest under a given set of agronomic management practices, pesticide characteristics, and aquifer sensitivity conditions.' The results of the aquifer sensitivity assessment on Navajo Nation and adjacent lands indicated relative sensitivity within the boundaries of the study area. About 22 percent of the study area was not an area of recharge to bedrock aquifers or an area of unconsolidated deposits and was thus assessed to have an insignificant potential for contamination. About 72 percent of the Navajo Nation study area was assessed to be in the categories of most potential or intermediate potential for contamination. About 6 percent of the study area was assessed to have the least potential for contamination, mostly in areas where the slope of the land surface is more than 12 percent. Nearly all fields on the Navajo Indian Irrigation Project were assessed to have the most potential for contamination. The assessment of ground-water vulnerability to pesticide contamination on the Navajo Indian Irrigation Project was based on pesticide application to various crops on part of the Navajo Indian Irrigation Project during 1997-99. The assessment indicated that ground water underlying fields of beans, wheat, barley, and alfalfa was most vulnerable to pesticide contamination; ground water underlying fields of corn and potatoes was intermediately vulnerable to pesticide contamination; and ground water underlying fields of hay was least vulnerable to pesticide contamination.

Blanchard, Paul J.

2002-01-01

308

Pure and shear-enhanced compaction bands in Aztec Sandstone  

NASA Astrophysics Data System (ADS)

We report on the occurrence of deformation bands in Jurassic eolian Aztec Sandstone at Valley of Fire, Nevada, that accommodated roughly equal amounts of shear and band-perpendicular compaction by grain rearrangement and porosity collapse. These bands, referred to as shear-enhanced compaction bands, differ in orientation, structural arrangement, and microtexture from pure compaction bands that form perpendicular to the shortening direction. Shear-enhanced compaction bands are planar over tens of meters, and commonly composed of multiple parallel thinner strands. Pure compaction bands are less commonly planar, typically wavy or chevron in geometry, and composed of single strands. Shear-enhanced compaction bands are inferred to form at 38-53° relative to the maximum compressive principal stress, and thus differ from compactive shear bands that form at distinctly lower angles. While shear offsets along shear-enhanced compaction bands are only about 1/10th of the band thickness, by contrast, shear offsets may be large for compactive shear bands with formation of slip surfaces. Based on inferred timing and burial conditions, we interpret that the formation of shear-enhanced and pure compaction bands requires large initial porosity close to the loose packing porosity, good sorting, and high effective maximum compressive principal stress of about 20 MPa.

Eichhubl, Peter; Hooker, John N.; Laubach, Stephen E.

2010-12-01

309

Middle Jurassic Oseberg delta, northern North Sea: A sedimentological and sequence stratigraphic interpretation  

SciTech Connect

The Aalenian Oseberg Formation (0-80 m thick) is an important reservoir unit in the Middle Jurassic Brent Group in the northern North Sea, consisting of multiple sets of sandy Gilbert-type deltas. Small-scale (1.5-10 m) fining-upward units seen in the gamma-ray log correspond with individual delta sets, as independently confirmed by steepening-upward trends seen in the dip log. Within each set, the steep foreset slopes typically show thinly bedded sandstone facies (avalanche grain flows), whereas the lower foreset slopes, toesets, and bottomsets are formed largely by massive sandstone facies (sandy debris flows). On an intermediate scale (up to 40 m), the gamma-ray logs show both fining-upward and coarsening-upward trends through stacked delta sets, and these trends, traceable between wells, are interpreted in terms of decelerating and accelerating rates of relative sea level rise, respectively. The relative abundance of the sandy debris-flow deposits reflects a periodic and significant instability of the delta`s upper foreset slope, probably during times of increased water depth in front of the delta. The normal progradation of individual Gilbert-type sets, however, is likely to have been along a subhorizontal topography during periods of little or no change in water depth. The long-term change to produce the observed vertical stacking of deltaic sets was one of a generally rising relative sea level.

Muto, T. [Nagasaki Univ. (Japan); Steel R.J. [Univ. of Wyoming, Laramie, WY (United States)

1997-07-01

310

Model for isopaching Jurassic-age Norphlet Formation in Mobile Bay, Alabama area  

SciTech Connect

Deep gas was discovered in the Norphlet Sandstone of Mobile Bay Alabama in 1979. Sixteen wells, of which Exxon Company, U.S.A. has had an interest in eight, have tested gas from depths greater than 20,000 ft and at an average rate of 19 million ft/sub 3/ of gas per day. The dominant structural features in Mobile Bay are large east-west-trending salt-supported anticlines associated with salt pull-apart listric normal faulting. Throws on these faults measure up to 1000 ft. Individual structures have dimensions as large as 15 mi in an east-west strike direction and 8 mi in a north-south dip direction. The Jurassic age (Callovian) Norphlet of Mobile Bay is characterized by eolian dune sand deposits up to 700 ft thick. An important factor affecting future development drilling is the accurate prediction of reservoir thickness. This presentation shows that an integrated study of seismic and well data has facilitated the development of a geological model for isopaching the Norphlet Formation. The isopach exhibits a strong north-northwest-south-southeast orientation of parallel thicks and thins. These trends are believed to be the result of original eolian deposition of complex linear dunes in the Norphlet Sandstone. The major east-west structural grain of faults and anticlines overprints this preserved depositional trend.

Torres, L.F.

1989-03-01

311

Total petroleum systems of the Pelagian Province, Tunisia, Libya, Italy, and Malta; the Bou Dabbous, Tertiary and Jurassic-Cretaceous composite  

USGS Publications Warehouse

Undiscovered conventional oil and gas resources were assessed within total petroleum systems of the Pelagian Province (2048) as part of the U.S. Geological Survey World Petroleum Assessment 2000. The Pelagian Province is located mainly in eastern Tunisia and northwestern Libya. Small portions of the province extend into Malta and offshore Italy. Although several petroleum systems may exist, only two ?composite? total petroleum systems were identified. Each total petroleum system comprises a single assessment unit. These total petroleum systems are called the Bou Dabbous?Tertiary and Jurassic-Cretaceous Composite, named after the source-rock intervals and reservoir-rock ages. The main source rocks include mudstone of the Eocene Bou Dabbous Formation; Cretaceous Bahloul, Lower Fahdene, and M?Cherga Formations; and Jurassic Nara Formation. Known reservoirs are in carbonate rocks and sandstone intervals throughout the Upper Jurassic, Cretaceous, and Tertiary sections. Traps for known accumulations include fault blocks, low-amplitude anticlines, high-amplitude anticlines associated with reverse faults, wrench fault structures, and stratigraphic traps. The estimated means of the undiscovered conventional petroleum volumes in total petroleum systems of the Pelagian Province are as follows: [MMBO, million barrels of oil; BCFG, billion cubic feet of gas; MMBNGL, million barrels of natural gas liquids] Total Petroleum System MMBO BCFG MMBNGL Bou Dabbous?Tertiary 667 2,746 64 Jurassic-Cretaceous Composite 403 2,280 27

Klett, T.R.

2001-01-01

312

Jurassic hydrocarbon exploration of southern Florida  

SciTech Connect

South Florida Jurassic exploration has been overlooked as a viable exploration target due to lack of data and plate-tectonics application. In Florida, {open_quotes}basement{close_quotes} is defined as crystalline, igneous, metamorphic, and unmetamorphosed sediments of Paleozoic age. Age-dating of zircons has proven that the Florida lower Paleozoic terrane is not akin to that of North America but is part of the West African Guinean shield. Previous published reconstructions of late Paleozoic fits of crustal plates and continents have failed to account for the differences in peninsula Florida basement and the geologic and tectonic continuities of peninsula Florida, Yucatan, Cuba, Hispaniola, and Bahamas. Pre-Atlantic reconstruction of the Gulf of Mexico in this study proposes that there was a Florida connection to Yucatan-Cuba-Africa during the Triassic. This reconstruction also shows that the Jurassic sediments that are well known in the northern Gulf Coast should have been deposited in similar depositional environments in southern Florida. Deep drilling on the Florida peninsula has confirmed this hypothesis. By using plate tectonic reconstruction based on the rising of the North Atlantic Ocean and evidence from petrology of basement samples from deep wells together with petrographic analyses of Jurassic sediments, a Smackover-equivalent exploration play can be developed. Petrographic and petrophysical analysis of these wells that have encountered Jurassic marine shales, anhydrite, dolomite, carbonate, and elastic sediments has determined that these sediments are from shallow-water subtidal, tidal, intertidal, and supratidal environments. Excellent gas shows, oil stain in the pores and high TOC values in the marine shales, indicate that large accumulations of hydrocarbon are present.

Mitchell-Tapping, H.J. [Retog, Inc., DeSoto, TX (United States)

1994-09-01

313

Dakota sandstone facies, western Oklahoma panhandle  

Microsoft Academic Search

The Cretaceous Dakota Sandstone in Cimarron County comprised three sandstone units and intervening mudrocks; it overlies the Kiowa Shale Member of the Purgatoire Formation. Deposits include shoreface, beach (foreshore) and dune, estuarine and tidal channel, marine marginal bay and swamp\\/marsh in a generally progradational sequences associated with marine regression in the Western Interior. The shoreface sand, characterized by ripple lamination,

E. Atalik; C. F. Mansfield

1984-01-01

314

Snow-covered Sandstone at Bryce Canyon  

USGS Multimedia Gallery

Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolomite that caps them and the sandstone that forms their base. Bryce Canyon is also home to large numbe...

315

Sandstone Strata in Capitol Reef National Park  

USGS Multimedia Gallery

A detail view of some sandstone strata within Capitol Reef National Park. Capitol Reef is primarily made up of sandstone formations within the Waterpocket Fold, monocline that extends nearly 100 miles. A monocline is a step-like fold in rock strata that can resemble an enormous wrinkle in the earth....

316

The origin of Jurassic reefs: Current research developments and results  

Microsoft Academic Search

Summary  In order to elucidate the control of local, regional and global factors on occurrence, distribution and character of Jurassic\\u000a reefs, reefal settings of Mid and Late Jurassic age from southwestern Germany, Iberia and Romania were compared in terms of\\u000a their sedimentological (including diagenetic), palaeoecological, architectural, stratigraphic and sequential aspects. Upper\\u000a Jurassic reefs of southern Germany are dominated by siliceous sponge—microbial

Reinhold R. Leinfelder; Manfred Krautter; Ralf Laternser; Martin Nose; Dieter U. Schmid; Günter Schweigert; Winfried Werner; Helmut Keupp; Hartmut Brugger; Regina Herrmann; Ursula Rehfeld-Kiefer; Johannes H. Schroeder; Carsten Reinhold; Roman Koch; Arnold Zeiss; Volker Schweizer; Heinrich Christmann; Götz Menges; Hanspeter Luterbacher

1994-01-01

317

Late Paleozoic to Jurassic tectonic evolution of the Bogda area (northwest China): Evidence from detrital zircon U-Pb geochronology  

NASA Astrophysics Data System (ADS)

Since the Cenozoic, the Tian Shan is rejuvenated by crustal shortening related to the ongoing India-Asia collision. However, the tectonic process prior to the Cenozoic remains ambiguous, especially in the Bogda area of the eastern Tian Shan. The continuous Late Paleozoic-Mesozoic sequences in the Bogda area record abundant information about the basin-mountain interaction. U-Pb (LA-ICP-MS) dating of detrital zircons from seven sandstone samples from Permian to Jurassic was used to investigate the changes of provenance and basin-mountain interaction in the Bogda area. During the Permian, proximal and synchronous pyroclastic materials were the major source. The Late Paleozoic magmatic belt in the North Tian Shan (NTS) had gradually become one of the main sources by the Late Permian, which implies the uplift and exhumation in the NTS area. This is interpreted in terms of near-source sedimentation in basin developing in a post-orogenic extension setting. The large range of U-Pb ages of detrital zircons observed in the Early-Middle Jurassic sediments encompasses most of the available sources implying a wide drainage pattern developing on a rather flat topography. Re-emergence of the Early Permian peak in the spectrum implies that the Bogda Mountains has existed as a gentle positive relief and began to provide materials to the submountain regions. The southern Junggar Basin extended towards to the south and evolved as a passively subsiding basin from the Middle Triassic to the Middle Jurassic. However, the synchronous pyroclastic (tuff) and the exhumed late Paleozoic detrital materials from the uplifted Bogda Mountains were the major component of the Upper Jurassic sediments. Associated to the conglomerate in the Kalaza Formation, the basin-range evolution entered a compression uplift stage. The basin pattern evolution of the Bogda area is consistent with that of the southern Junggar Basin.

Tang, Wenhao; Zhang, Zhicheng; Li, Jianfeng; Li, Ke; Chen, Yan; Guo, Zhaojie

2014-06-01

318

The Navajo Environmental Protection Commission: Developing the Capabilities for Environmental Impact Assessment and Regulation  

ERIC Educational Resources Information Center

To develop effective/efficient environmental impact assessment and regulatory capabilities, the Navajo Environmental Protection Commission will need to commit more of its limited resources to building the political support which will exert real influence at the pre-commitment stages of development decision making. (JC)

Cortner, Hanna J.

1976-01-01

319

Classroom Resiliency--A Comparison of Navajo Elementary Students' Perceptions of Their Classroom Environment  

ERIC Educational Resources Information Center

The purpose of this study was to determine if there was a gender difference in how students perceived their classroom environment on the Navajo Nation public school. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be…

Piechowski, Alta Begay

2011-01-01

320

From Break Dancing to Heavy Metal: Navajo Youth, Resistance, and Identity.  

ERIC Educational Resources Information Center

Research on Navajo youth lives and choices examines the messages conveyed through their breakdancing and heavy-metal music. Central to the messages is resistance to assimilation into mainstream culture and maintenance of their cultural identity in a racially divided community. (MMU)

Deyhle, Donna

1998-01-01

321

SUSTAINABILITY OF MOUNTAIN SOURCES OF WATER FOR THE NAVAJO NATION UNDER THE IMPACT OF CLIMATE CHANGE  

EPA Science Inventory

This model may assist Navajo communities to implement strategies that prepare the communities for impacts of climate change. Other tribes may be encouraged to develop similar hydrologic models to help understand the hydrologic responses of climate change in their area and h...

322

Content Analysis Schedule for Bilingual Education Programs: Bilingual Education Project for Navajo.  

ERIC Educational Resources Information Center

This content analysis schedule for the Bilingual Education Project for Navajo of Monticello, Utah, presents information on the history, funding, and scope of the project. Included are sociolinguistic process variables such as the native and dominant languages of students and their interaction. Information is provided on staff selection and the…

La Noue, Joan; Shore, Marietta Saravia

323

Cross Country, Rodeo, Archery: Navajo Athletic Programs Give Students Running Start  

ERIC Educational Resources Information Center

While tribal college athletic programs were not designed to market the colleges, there is no denying they have generated positive attention and have perhaps even helped to highlight the colleges' purpose. Dine College and Navajo Technical College are among a handful of tribal colleges who have made athletic programs a priority. They have since…

Johnson, Natasha Kaye

2009-01-01

324

Qualitative Study of the Use of Traditional Healing by Asthmatic Navajo Families  

ERIC Educational Resources Information Center

Despite increasing prevalence of asthma among American Indians and/or Alaska Natives, little is known about their use of traditional healing in its management. A convenience sample of 24 Navajo families with asthmatic members (n=35) was interviewed between June 1997 and September 1998. While 46% of families had previously used traditional healing,…

Van Sickle, David; Morgan, Frank; Wright, Anne L.

2003-01-01

325

The Goal Wheel: Adapting Navajo Philosophy and the Medicine Wheel to Work with Adolescents  

ERIC Educational Resources Information Center

The purpose of this article is to describe a group counseling model that is based on the indigenous medicine wheel as well as Navajo philosophy by which to help troubled adolescents restore harmony and balance in their lives, through establishing goals and sequential steps to accomplish these goals. The authors call this model the Goal Wheel. A…

Garner, Holly; Bruce, Mary Alice; Stellern, John

2011-01-01

326

The Navajo Learning Network and the NASA Life Sciences/AFOSR Infrastructure Development Project  

NASA Technical Reports Server (NTRS)

The NSF-funded Navajo Learning Network project, with help from NASA Life Sciences and AFOSR, enabled Dine College to take a giant leap forward technologically - in a way that could never had been possible had these projects been managed separately. The combination of these and other efforts created a network of over 500 computers located at ten sites across the Navajo reservation. Additionally, the college was able to install a modern telephone system which shares network data, and purchase a new higher education management system. The NASA Life Sciences funds further allowed the college library system to go online and become available to the entire campus community. NSF, NASA and AFOSR are committed to improving minority access to higher education opportunities and promoting faculty development and undergraduate research through infrastructure support and development. This project has begun to address critical inequalities in access to science, mathematics, engineering and technology for Navajo students and educators. As a result, Navajo K-12 education has been bolstered and Dine College will therefore better prepare students to transfer successfully to four-year institutions. Due to the integration of the NSF and NASA/AFOSR components of the project, a unified project report is appropriate.

1999-01-01

327

Pressures on Arizona Water and Energy Policy: Case Study of the Navajo Generating Station  

E-print Network

1 Pressures on Arizona Water and Energy Policy: Case Study of the Navajo Generating Station Sonya Fellowship #12;2 Arizona water concern at issue: Water's connection to energy and climate Water, climate, and energy are closely linked in Arizona. When a person turns on the tap in Tucson, part of that water

Fay, Noah

328

Of Mother Earth and Father Sky: A Photographic Study of Navajo Culture.  

ERIC Educational Resources Information Center

Utilizing 52 black and white photographs, the book tells a story about the Navajo people, their hopes and problems, the strategies they have adopted to cope with the problems, their interactions with each other and with the land, and their feelings about the land which provides a basis for their livelihood. Part of a series of curriculum materials…

McCarty, T. L.; And Others

329

The Economic Contributions of Women in a Rural Western Navajo Community.  

ERIC Educational Resources Information Center

Examines and enumerates economic changes that have occurred in the traditional rural Navajo community of Shonto. While women's net income contributions to Shonto's economy has declined, their position has seen only a slight erosion; their activities (sheep and goat husbandry, agriculture, arts and crafts) are still considered necessary and…

Russell, Scott C.; McDonald, Mark B.

1982-01-01

330

Recruitment and Retention of Federally Employed Physicians on the Navajo Indian Reservation.  

ERIC Educational Resources Information Center

Special difficulties surround the efforts of the Indian Health Service (IHS) to recruit and retain physicians for its extensive health care delivery systems on Indian reservations, particularly those of the Navajo. A comprehensive questionnaire survey obtained data on the background and attitudes of federal physicians practicing in each of the 8…

Brod, Rodney L.; And Others

331

Maslow's Hierarchy of Needs and Navajo Students' Struggle for Self Esteem.  

ERIC Educational Resources Information Center

Maslow's theory of a hierarchy of needs is used to analyze Navajo youths' struggles for identity, fulfillment, and self-esteem. Answers to the challenges of substance abuse, violence, and gang membership are offered based upon George Bearden's eight-step plan, which stresses the importance of understanding human needs to perceive and transform…

Walker, Kay

1996-01-01

332

Paleoenvironments and hydrocarbon potential of Upper Jurassic Norphlet Formation of southwestern Alabama and adjacent coastal water area  

SciTech Connect

Upper Jurassic Norphlet sediments in southwestern Alabama and the adjacent coastal water area accumulated under arid climatic conditions. The Appalachian Mountains of the eastern United States extended into southwestern Alabama, providing a barrier for air and water circulation during Norphlet deposition. Norphlet paleogeography was dominated by a broad desert plain rimmed to the north and east by the Appalachians and to the south by a developing shallow sea. Initiation of Norphlet sedimentation was a result of erosion of the southern Appalachians. Norphlet conglomerates were deposited in coalescing alluvial fans in proximity to an Appalachian source. The conglomeratic sandstones grade downdip into red-bed lithofacies that accumulated in distal portions of alluvial fan and wadi systems. Quartzose sandstones (Denkman Member) were deposited as dune and interdune sediments on a broad desert plain. The source of the sand was the updip and adjacent alluvial fan, plain, and wadi deposits. A marine transgression was initiated late in Denkman deposition, resulting in the reworking of previously deposited Norphlet sediments. Norphlet hydrocarbon potential in southwestern and offshore Alabama is excellent with four oil and gas fields already established. Petroleum traps discovered to date are primarily structural traps involving salt anticlines, faulted salt anticlines, and extensional fault traps associated with salt movement. Reservoir rocks consist of quartzose sandstones, which are principally eolian in origin. Smackover algal carbonate mudstones were probably the source for the Norphlet hydrocarbons.

Mancini, E.A.; Mink, R.M.; Bearden, B.L.

1984-09-01

333

Upper Jurassic Norphlet formation: new frontier for hydrocarbon prospecting in the central and eastern Gulf of Mexico regions  

SciTech Connect

Since the discovery of oil in 1967 from the Smackover Formation at Toxey field, Choctaw County, Alabama, and of condensate in 1968 from the Norphlet Formation at Flomaton field, Escambia County, Alabama, the Upper Jurassic has become the primary exploration target in southwestern Alabama. Norphlet petroleum traps in the region are principally combination traps involving favorable stratigraphy and salt anticlines (Copeland field), extensional fault traps associated with salt movement (Flomaton field), and faulted salt anticlines (Hatter's Pond and Lower Mobile Bay-Mary Ann fields). Reservoir rocks include marine, dune, and fluvial sandstone lithofacies. Sandstone porosity involves both primary intergranular and secondary dissolution and fracture. Smackover algal carbonate mudstone is probably the source for much of the Norphlet hydrocarbon, but downdip Norphlet marine shales may also be source rocks. The central and eastern Gulf of Mexico regions should continue to be excellent areas to explore for hydrocarbons in the years ahead. Successful Norphlet petroleum prospecting in the area has involved the identification of favorable sandstone lithofacies and structural hydrocarbon traps by using geologic and geophysical methods. Future Norphlet discoveries will require the delineation of stratigraphic and structural/stratigraphic combination hydrocarbon traps using seismic-stratigraphic techniques.

Mancini, E.A.; Mink, R.M.; Bearden, B.L.

1984-04-01

334

Upper Jurassic Norphlet formation: new frontier for hydrocarbon prospecting in the central and eastern Gulf of Mexico regions  

SciTech Connect

Since the discovery of oil in 1967 from the Smackover Formation at Toxey field, Choctaw County, Alabama, and of condensate in 1968 from the Norphlet Formation at Flomaton field, Escambia County, Alabama, the Upper Jurassic has become the primary exploration target in southwestern Alabama. Norphlet petroleum traps in the region are principally combination traps involving favorable stratigraphy and salt anticlines (Copeland field), exensional fault traps associated with salt movement (Flomaton field), and faulted salt anticlines (Hatter's Pond and Lower Mobile Bay-Mary Ann fields). Reservoir rocks include marine, dune, and fluvial sandstone lithofacies. Sandstone porosity involves both primary intergranular and secondary dissolution and fracture. Smackover algal carbonate mudstone is probably the source for much of the Norphlet hydrocarbon, but downdip Norphlet marine shales may also be source rocks. The central and eastern Gulf of Mexico regions should continue to be excellent areas to explore for hydrocarbons in the years ahead. Successful Norphlet petroleum prospecting in the area has involved the identification of favorable sandstone lithofacies and structural hydrocarbon traps by using geologic and geophysical methods. Future Norphlet discoveries will require the delineation of stratigraphic and structural/stratigraphic combination hydrocarbon traps using seismic-stratigraphic techniques.

Mancini, E.A.; Mink, R.M.; Bearden, B.L.

1984-04-01

335

Implications of an eolian sandstone unit of Basal Morrison Formation, central Wyoming  

SciTech Connect

A laterally discontinuous fine-grained quartzarenite occurs at the base of the Upper Jurassic Morrison Formation in the southern Big Horn and Powder River basins and in the Wind River basin. The sandstone unit is interpreted to be an eolianite. Evidence for this includes high-angle (20-35/sup 0/), medium to large-scale planar cross-beds that are tangential at the base, inversely graded foresets, and discrete dune formation in some areas. Cross-bed set thickness ranges from 1 to 10 m. Soft sediment deformation in the form of small-scale contortions is common in dune cross-stratification. The eolianite is 10-55 m thick and conformably overlies the transitional marine Windy Hill Sandstone Member of the upper Sundance Formation. Paleocurrent data suggest a northward transportation direction. On exposed planar surfaces of foresets, nonmarine ichnofauna are present including small vertebrate trackways. This eolian facies represents a unique setting within the predominantly fluvial and lacustrine mudstones of the Morrison Formation and may be indicative of localized small-scale uplifts associated with Sevier compressional activity to the west. Based upon lithology and stratigraphic position of the eolianite, the geological history of central Wyoming during late Oxfordian to early Kimmeridgian time can be reconstructed as follows: as the Sundance sea withdrew from central Wyoming, a blanket of lagoonal, lacustrine, and flood-plain mudstones and small channel sandstones were deposited in an area of very low topographical relief. In response to compression to the west, subtle uplifts occurred locally in south-central and southeastern Wyoming, resulting in erosion of the upper Sundance marine sandstones. Patches of windblown eroded fine sands were subsequently deposited within the nonmarine mudstones in nearby eolian environments to the north.

Weed, D.D.; Vondra, C.F.

1987-05-01

336

Jurassic detrital zircon U-Pb and Hf isotopic geochronology of Luxi Uplift, eastern North China, and its provenance implications for tectonic-paleogeographic reconstruction  

NASA Astrophysics Data System (ADS)

Relatively successive sequences of Late Mesozoic are preserved and exposed in Luxi Uplift (LU), eastern North China block (NCB), which is an important region to study the late Mesozoic tectonic evolution of the eastern NCB. In this study, in situ U-Pb ages and Hf isotopic analyses on detrital zircons from the sandstones of Jurassic Fangzi and Santai Formations in LU combining the analysis of sandstone detrital modes were performed, with an aim to trace the Jurassic sediment provenances and the tectonic-paleogeographic configuration of eastern NCB. Three sandstone samples (one from Fangzi Formation and two from Santai Formation) have very similar U-Pb age spectrums which can be divided into three major groups: Phanerozoic (I), Paleoproterozoic (II), and Neoarchean (III). Detrital zircons of Group II and Group III broadly match the age spectra of the basement of NCC which exposed extensively in the northern part. No middle Neoproterozoic magmatic zircons or Triassic metamorphic zircons were found in this study, ruling out the clastic provenance transported from the Sulu orogen to LU. Dominant zircon populations of Group Iare Late Paleozoic (250-393 Ma) recording the corresponding magmatic activities which are not found both in LU and its peripheral tectonic terranes, but can be well compared with that of the northern NCB (NNCB) and the Xing-Meng Orogenic Belt (XMOB). Furthermore, Hf isotope compositions of the Phanerozoic detrital zircons can be distinctly divided into two clusters with ?Hf(t) values ranging from -1.0 to +12.7 and -21.9 to -3.0, respectively resemble those from the XMOB and NCB (mainly from NNCB). Sandstone detrital modes analysis indicates the provenance came from the areas that have been eroded deeply to expose the basement rocks which accords with the tectonic setting of the NNCB. This research proposes that an evident mountain or provenance region once increasingly developed along NNCB during Early to Late Jurassic (182-155 Ma) due to the continuous collision of the Siberia and North China-Mongolian plates, easily shed mass clastic materials southward into the inner NCB and became the major provenance of Jurassic sediments in LU.

Xu, Jianqiang; Li, Zhong; Shi, Yonghong

2013-12-01

337

Suitability of Frigg, Åre, and Sognefjord Formation sandstones (North Sea) for storage of CO2  

NASA Astrophysics Data System (ADS)

The steady increase in concentration of CO2 in the atmosphere owing to the combustion of hydrocarbons is considered a major factor contributing to global warming. The storage of CO2 as subcritical gas in depleted oil and gas reservoirs and deep aquifers is considered a viable mitigation for reducing the impact of global temperature increase as a consequence of increased atmospheric CO2 (Hitcheon 1999, Bachu 2008). The volume of CO2 stored in the subsurface as supercritical liquid in any given sedimentary rock formation could be limited to <1% of the total pore space. Storage of larger volumes might lead to increased pressure and cause injection rates to undergo exponential decline (Ehlig-Economides and Economides 2010). Petrographic investigations of samples of sandstone from three quartz-rich sandstone formations in the Norwegian part of the North Sea, i.e. Tertiary Frigg Formation, Lower Jurassic Åre Formation, and Upper Jurassic Sognefjord Formation, reveal that all three sandstone formations exhibit features that favor suitability for CO2 storage. Favorable features include: 1) Abundant effective porosity 2) Stable mineralogy (i.e. abundant quartz) 3) Lack of chemically unstable detrital minerals (i.e. potassium and plagioclase feldspar, carbonates, volcanic rock fragments) 4) Lack of acid-soluble cements (e.g. iron-chlorite clay, siderite, calcite, or dolomite) 5) Lack of fresh-water sensitive (expansive) clay mineral cements (e.g. montmorillonite and mixed-layer illite-smectite (ML-IS). Intergranular porosity for each of the formations is estimated to be 28-31% of total rock volume for the Frigg Formation, 19-34% for the Åre Formation, and 16-29% for the Sognefjord Formation. Intergranular porosity of sandstones in each of the three formations is very well connected. Pore-throat radii of intergranular pores are interpreted to be significantly larger than 0.5 ?m. Pore throats are not occluded by clay mineral cements, resulting in excellent estimated permeability. Microporosity within pore-filling kaolinite cement for the Frigg Formation is 2-5% of total rock volume, for the Åre Formation 3-6%, and for the Sognefjord Formation 3-10%. Irreducible water saturation caused by high specific surface area of kaolinite cements and pore throat radii within kaolinite cement of <0.5 ?m is interpreted to be minor, with the exception of one sample from the Sognefjord Formation.

Saether, O. M.; Webb, J. C.; Wissing, B. W.; Bøe, R.

2012-12-01

338

Exploration models for submarine slope sandstones  

SciTech Connect

Recent published studies have demonstrated a far greater potential than previously recognized for submarine slope sandstones to contain significant oil and gas reserves in the Gulf Coast and elsewhere. Comparison of modern slopes with outcrop and subsurface analogs from several areas provided the framework for developing the following submarine slope sandstone exploration models: submarine canyon fill, slope gully/channel fill, slope spillover sand sheets, and intraslope basin fill. Submarine canyon fill is mainly shale, but sandstone beds that form stratigraphic traps may be present. Canyon shale fill juxtaposed against older sandstones can also form stratigraphic traps. Gully/channel fills are sandstones deposited on shallow-gradient slopes or ramps. The proximity of these sandstones to slope shales provides opportunities for stratigraphic traps to develop. Spillover sand sheets are resedimented from a shelf to a shallow-gradient slope and are associated with gully/channel fills. Intraslope basin fill is mainly shale, but elongate, sheetlike, or fan-shaped turbidite sandstones can provide stratigraphic traps. In all of these deposits, slope shales may be sufficiently enriched in organic carbon to be potential hydrocarbon source rocks; the potential for organic-rich shales to accumulate is highest in intraslope basin fill.

Slatt, R.M.

1986-09-01

339

Age spectra of detrital zircon of the Jurassic clastic rocks of the Mino-Tanba AC belt in SW Japan: Constraints to the provenance of the mid-Mesozoic trench in East Asia  

NASA Astrophysics Data System (ADS)

U-Pb ages of detrital zircon grains were determined from an upper Middle Jurassic siliceous mudstone and two lower Upper Jurassic sandstones of the Mino-Tanba belt, Southwest Japan, by Laser-ablation ICPMS. The age spectra of detrital zircon grains of the three analyzed samples show multiple age clusters: 175-198 Ma (Early Jurassic), 202-284 Ma (Permian to Triassic), 336-431 Ma (Silurian to Carboniferous), and 1691-2657 Ma (Neoarchean to Paleoproterozoic). As per the Precambrian grains, the prominent peak exists around 1800-2000 Ma in all analyzed samples. The age clusters of 175-198 Ma, 202-284 Ma, and 336-431 Ma suggest that pre-Middle Jurassic Japan has exposed older granitic batholiths. The corresponding batholiths occur in the Cathaysian part of South China block. In contrast, the absence of them in modern Japan suggests that these batholiths were totally consumed by post-Jurassic tectonic erosion. The Neoarchean to Paleoproterozoic detrital zircon grains were derived from South China, North China, or possibly both of them; nonetheless, the circumstantial geologic lines of evidence point to South China, in particular to Cathaysia, rather than North China.

Fujisaki, Wataru; Isozaki, Yukio; Maki, Kenshi; Sakata, Shuhei; Hirata, Takafumi; Maruyama, Shigenori

2014-07-01

340

Cotton Valley sandstones of east Texas: a log-core study  

SciTech Connect

The Cotton Valley sandstone is associated with many fields in east Texas and north Louisiana and is of upper Jurassic age. The sand-shale sequence is encountered at depths ranging from 8000 to 12,000 ft. The average reservoir temperature is 250 F. The gross sand interval may be 1500 ft thick with many correlative producing zones. It is typified by low porosities and permeabilities. Hydraulic fracturing is almost a universal practice. Many productive zones exhibit water contacts, therefore, the sizing of fracture treatments becomes critical. The first priority is to identify potentially productive intervals. This can only be accomplished through accurate calculations of porosity and water saturation. Test conducted on reservoir rock material aid in the evaluation of log responses. Such tests provide a base for selecting the best logging tools for determining porosity. They provide measured values for variables required in water saturation formulas and confirm lithologies indicated from log calculations. 12 references.

Wilson, D.A.; Hensel, W.M. Jr.

1982-01-01

341

Feldspar diagenesis in the Yowlumne sandstone, Kern County, California  

E-print Network

. . Cathodoluminescence. Trend Analysis PETROLOGY AND MINERALOGY OF THE YOWLUMNE SANDSTONE. . . 25 26 27 28 28 29 29 29 30 Sandstone Texture. Composition. Secondary Rock Property Measurements. . Porosity Analysis. Feldspar Alteration. Clay Mineralogy.... Clay Distribution and Morphology. . . . . . Mineralogy of Interbedded Shales. . . . . . 30 30 37 37 42 51 59 70 GEOCHEMICAL CQNSIDERATIQNS OF FELDSPAR ALTERATIONS IN THE YOWLUMNE SANDSTONE. 72 EFFECTS QF YOWLUMNE SANDSTONE DIAGENESIS...

Pike, John David

1981-01-01

342

PARTITOMORPHITAE, A NEW SUBGROUP OF TRIASSIC AND JURASSIC ACRITARCHS  

Microsoft Academic Search

Three new genera of acritarchs are described: Rugidinium, comprising two new species, R. ornatum and ,R. undulatum, from the Bajocian (Jurassic) of Canada; Thuledinium, represented by a single species, T. groenlandicum , from the Callovian (Jurassic) of Greenland; and Teichertodinium, represented by a single species, T. triassicum, from the Triassic (Anisian) of Pakistan. All three genera share the charac^ teristics

STANLEY A. J. POCOCK; WILLIAM A. S. SARJEANT

343

A new carnivorous dinosaur from the Late Jurassic Solnhofen archipelago  

Microsoft Academic Search

Small Late Jurassic theropod dinosaurs are rare worldwide. In Europe these carnivorous dinosaurs are represented primarily by only two skeletons of Compsognathus, neither of which is well preserved. Here we describe a small new theropod dinosaur from the Late Jurassic period of Schamhaupten in southern Germany. Being exquisitely preserved and complete from the snout to the distal third of the

Ursula B. Göhlich; Luis M. Chiappe

2006-01-01

344

Massive dissociation of gas hydrate during a Jurassic  

E-print Network

.............................................................................................................................................. In the Jurassic period, the Early Toarcian oceanic anoxic event (about 183 million years ago) is associated hydrate during a Jurassic oceanic anoxic event Stephen P. Hesselbo*, Darren R. Gro¨cke*, Hugh C. Jenkyns together, these 13 C curves depict a period of gradual rise in isotopic values which is interrupted

Hesselbo, Stephen P.

345

Reinterpreting the morphology of the Jurassic scorpion Liassoscorpionides  

Microsoft Academic Search

The fossil scorpion (Arachnida: Scorpiones) Liassoscorpionides schmidti Bode, 1951, the youngest scorpion to be assigned to a putative aquatic clade, from the early Jurassic (Toarcian) of Hondelage near Braunschweig, Germany, is redescribed. It is the only unequivocal Jurassic scorpion, but there is in fact no evidence to support an aquatic mode of life. Some features hint that it might be

Jason A. Dunlop; Carsten Kamenz; Gerhard Scholtz

2007-01-01

346

DEFORMATION AND FRACTURE OF POORLY CONSOLIDATED MEDIA - Borehole Failure Mechanisms in High-Porosity Sandstone  

SciTech Connect

We investigated failure mechanisms around boreholes and the formation of borehole breakouts in high-porosity sandstone, with particular interest to grain-scale micromechanics of failure leading to the hitherto unrecognized fracture-like borehole breakouts and apparent compaction band formation in poorly consolidated granular materials. We also looked at a variety of drilling-related factors that contribute to the type, size and shape of borehole breakouts. The objective was to assess their effect on the ability to establish correlations between breakout geometry and in situ stress magnitudes, as well as on borehole stability prediction, and hydrocarbon/water extraction in general. We identified two classes of medium to high porosity (12-30%) sandstones, arkosic, consisting of 50-70% quartz and 15 to 50% feldspar, and quartz-rich sandstones, in which quartz grain contents varied from 90 to 100%. In arkose sandstones critical far-field stress magnitudes induced compressive failure around boreholes in the form of V-shaped (dog-eared) breakouts, the result of dilatant intra-and trans-granular microcracking subparallel to both the maximum horizontal far-field stress and to the borehole wall. On the other hand, boreholes in quartz-rich sandstones failed by developing fracture-like breakouts. These are long and very narrow (several grain diameters) tabular failure zones perpendicular to the maximum stress. Evidence provided mainly by SEM observations suggests a failure process initiated by localized grain-bond loosening along the least horizontal far-field stress springline, the packing of these grains into a lower porosity compaction band resembling those discovered in Navajo and Aztec sandstones, and the emptying of the loosened grains by the circulating drilling fluid starting from the borehole wall. Although the immediate several grain layers at the breakout tip often contain some cracked or even crushed grains, the failure mechanism enabled by the formation of the compaction band is largely non-dilatant, a major departure from the dilatant mechanism observed in Tablerock sandstone. The experimental results suggest that unlike our previous assertion, the strength of grain bonding and the mineral composition, rather than the porosity, are major factors in the formation of compaction bands and the ensuing fracture-like breakouts. Some breakout dimensions in all rocks were correlatable to the far-field principal stresses, and could potentially be used (in conjunction with other information) as indicators of their magnitudes. However, we found that several factors can significantly influence breakout geometry. Larger boreholes and increased drilling-fluid flow rates produce longer fracture-like breakouts, suggesting that breakouts in field-scale wellbores could reach considerable lengths. On the other hand, increased drilling-fluid weight and increased drill-bit penetration rate resulted in a decrease in breakout length. These results indicate that breakout growth can be controlled to some degree by manipulating drilling variables. Realizing how drilling variables impact borehole breakout formation is important in understanding the process by which breakouts form and their potential use as indicators of the far-field in situ stress magnitudes and as sources of sand production. As our research indicates, the final breakout size and mechanism of formation can be a function of several variables and conditions, meaning there is still much to be understood about this phenomenon.

Bezalel c. Haimson

2005-06-10

347

Regional porosity trends of the Upper Jurassic Norphlet Formation in southwestern Alabama and vicinity, with comparisons to formations of other basins  

SciTech Connect

Sandstone porosity of the Upper Jurassic Norphlet Formation in southwestern Alabama and vicinity decreases systematically as depth and thermal maturity increase over a wide range. Median porosity is about 25% where equivalent vitrinite reflectance (R[sub o]) is slightly over 0.7% in the northern part of the study area (Clarke County, Mississippi). Median porosity is reduced to 8% where R[sub o] approaches 2.7% in the southern part of the study area (state waters of Mobile Bay). Porosity of the cemented, tight zone at the top of the Norphlet in downdip locations is roughly 10% lower than porosities of facies underlying the tight zone, but nevertheless is slightly above the norm for other sandstones at similar R[sub o] levels. Porosity of dune facies is consistently 2-5% higher than that of interdune facies, other factors being equal. Our data show 3-6% higher porosity in chlorite-dominated intervals relative to intervals where illite is the dominant clay mineral. Norphlet porosity has little or no correlation with position relative to the present-day hydrocarbon-water contact. Based on comparisons at similar R[sub o] levels, median (50th-percentile) Norphlet porosity exceeds porosities of [open quotes]typical[close quotes] sandstones in other basins by more than a factor of two throughout the study area. Even the lower (10th-percentile) Norphlet porosities are higher than median porosities of sandstones in general. 48 refs., 12 figs., 5 tabs.

Schmoker, J.W.; Schenk, C.J. (Geological Survey, Denver, CO (United States))

1994-02-01

348

Deposition and deformation of fluvial-lacustrine sediments of the Upper Triassic-Lower Jurassic Whitmore Point Member, Moenave Formation, northern Arizona  

NASA Astrophysics Data System (ADS)

The stratigraphic section of the Upper Triassic-Lower Jurassic Whitmore Point Member of the Moenave Formation at Potter Canyon, Arizona, comprises c. 26 m of gray to black shales and red mudstones interbedded with mainly sheet-like siltstones and sandstones. These strata represent deposition from suspension and sheetflow processes in shallow, perennial meromictic to ephemeral lakes, and on dry mudflats of the terminal floodout of the northward-flowing Moenave stream system. The lakes were small, as indicated by the lack of shoreline features and limited evidence for deltas. Changes in base level, likely forced by climate change, drove the variations between mudflat and perennial lacustrine conditions. Lenticular sandstones that occur across the outcrop face in the same stratigraphic interval in the lower part of the sequence represent the bedload fill of channels incised into a coarsening-upward lacustrine sequence following a fall in base level. These sandstones are distinctive for the common presence of over-steepened bedding, dewatering structures, and less commonly, folding. Deformation of these sandstones is interpreted as aseismic due to the lack of features typically associated with seismicity, such as fault-graded bedding, diapirs, brecciated fabrics and clastic dikes. Rapid deposition of the sands on a fluid-rich substrate produced a reverse density gradient that destabilized, and potentially fluidized the underlying, finer-grained sediments. This destabilization allowed synsedimentary subsidence of most of the channel sands, accompanied by longitudinal rotation and/or ductile deformation of the sand bodies.

Tanner, Lawrence H.; Lucas, Spencer G.

2010-01-01

349

Compaction of Norphlet sandstones, Rankin County, Mississippi  

Microsoft Academic Search

Fabric and porosity changes resulting from compaction were studied in sandstones from three cores sampled at depths between 15,900 and 22,500 ft. Point counts of 30 thin sections indicate that 0.4% of the rock volume was lost by ductile grain deformation and 3% by pressure solution at both grain contacts and at widely spaced stylolites. Pre-cement porosities of eolian sandstone

1987-01-01

350

Lower Cretaceous Avile Sandstone, Neuquen basin, Argentina - Exploration model for a lowstand clastic wedge in a back-arc basin  

SciTech Connect

The Neuquen basin of western Argentina is a back-arc basin that was occupied by epeiric seas during much of Jurassic and Cretaceous time. The Avile Sandstone Member of the Agrio Formation records a pronounced but short-lived regression of the Agrio sea during middle Hauterivian (Early Cretaceous) time. Abrupt lowering of relative sea level resulted in emergence and erosion of the Agrio sea floor; shoreline and fluvial facies characteristic of the Centenario Formation shifted basinward. The Avile rests erosionally upon lower Agrio shale over a large area; well-sorted, porous sandstones within the member pinch out laterally against the base-Avile erosional surface. Avile deposition closed with an abrupt transgression of the shoreline to the approximate position it had occupied prior to the Avile regression. The transgressive deposits are carbonate rich, reflecting starvation of the basin as a consequence of sea-level rise. The Avile lowstand clastic wedge consists predominantly of sandstones deposited in fluvial to shallow-marine paleoenvironments; eolian sandstones probably constitute an important component in the eastern part of the area. The sandstones locally have excellent reservoir characteristics; they constitute the reservoirs in the Puesto Hernandez, Chihuido de la Sierra Negra, and Filo Morado fields. The pinch-out of the Avile lowstand clastic wedge has the potential to form stratigraphic traps in favorable structural positions. The depositional model indicates that there may be a viable stratigraphic play to be made along the Avile pinch-out in the deep, relatively undrilled, northwestern part of the Neuquen basin.

Ryer, T.A. (Apache International, Denver, CO (United States))

1991-03-01

351

"Sydney sandstone": Heritage Stone from Australia  

NASA Astrophysics Data System (ADS)

Sydney is Australia's oldest city being founded in 1788. The city was fortunate to be established on an extensive and a relatively undeformed layer of lithified quartz sandstone of Triassic age that has proved to be an ideal building stone. The stone has been long identified by geologists as the Hawkesbury Sandstone. On the other hand the term "Sydney sandstone" has also been widely used over a long period, even to the extent of being utilised as the title of published books, so its formal designation as a heritage stone will immediately formalise this term. The oldest international usage is believed to be its use in the construction of the Stone Store at Kerikeri, New Zealand (1832-1836). In the late 19th century, public buildings such as hospitals, court houses as well as the prominent Sydney Town Hall, Sydney General Post Office, Art Gallery of New South Wales, State Library of New South Wales as well as numerous schools, churches, office building buildings, University, hotels, houses, retaining walls were all constructed using Sydney sandstone. Innumerable sculptures utilising the gold-coloured stone also embellished the city ranging from decorative friezes and capitals on building to significant monuments. Also in the late 19th and early 20th century, Sydney sandstone was used for major construction in most other major Australian cities especially Melbourne, Adelaide and Brisbane to the extent that complaints were expressed that suitable local stone materials were being neglected. Quarrying of Sydney sandstone continues today. In 2000 it was recorded noted that there were 33 significant operating Sydney sandstone quarries including aggregate and dimension stone operations. In addition sandstone continues to be sourced today from construction sites across the city area. Today major dimension stone producers (eg Gosford Quarries) sell Sydney sandstone not only into the Sydney market but also on national and international markets as cladding and paving products as well as block. Recent international projects by Gosford Quarries include Mishima Golf Club in Japan, Al Awadi Tower in Kuwait, New World Resort in China and a Hard Rock Café in Florida, USA. Arguably Sydney sandstone is Australia's most prominent potential Global Heritage Stone Resource and details are readily available in existing publications to make the nomination.

Cooper, Barry; Kramar, Sabina

2014-05-01

352

Multistage variable probability forest volume inventory. [Defiance Unit of the Navajo Nation in Arizona and Colorado  

NASA Technical Reports Server (NTRS)

The net board foot volume (Scribner log rule) of the standing Ponderosa pine timber on the Defiance Unit of the Navajo Nation's forested land was estimated using a multistage forest volume inventory scheme with variable sample selection probabilities. The inventory designed to accomplish this task required that both LANDSAT MSS digital data and aircraft acquired data be used to locate one acre ground splits, which were subsequently visited by ground teams conducting detailed tree measurements using an optical dendrometer. The dendrometer measurements were then punched on computer input cards and were entered in a computer program developed by the U.S. Forest Service. The resulting individual tree volume estimates were then expanded through the use of a statistically defined equation to produce the volume estimate for the entire area which includes 192,026 acres and is approximately a 44% the total forested area of the Navajo Nation.

Anderson, J. E. (principal investigator)

1979-01-01

353

Vertebrate fossils and trace fossils in Upper Jurassic-Lower cretaceous red beds in the Atacama region, Chile  

NASA Astrophysics Data System (ADS)

Pterosaur, dinosaur, and crocodile bones are recorded here for the first time in Upper Jurassic-Lower Cretaceous red beds in the Atacama region east of Copiapó, Chile. Trace fossils produced by vertebrate animals include the footprints of theropod dinosaurs and the depressions of sandstone laminae interpreted as burrows and foot impressions. The fossils occur in the 1500-meter-thick Quebrada Monardes Formation, which consists predominantly of the aeolian and alluvial deposits of a semi-arid terrestrial environment. Vertebrate fossils are very rare in Chile. Dinosaur bones and footprints have previously been recorded at only seven locations, and pterosaur remains at only one location. The newly discovered dinosaur bones are the oldest to be described in Chile.

Bell, C. M.; Suárez, M.

354

Sedimentary evolution and palaeogeography of mid-Jurassic deposits of the Central High Atlas, Morocco  

NASA Astrophysics Data System (ADS)

In the axis of the Moroccan Central High Atlas rift basin, Toarcian-Middle Jurassic deposits, excepting the early Toarcian Tagoudite Formation, are represented by two formations - Agoudim and Tazigzaout - comprising clays, marls and limestones. On the margins of the basin, the lateral equivalents of these two formations are dolostone-dominated and show the lithological and environmental characteristics of the Bin El Ouidane Group recognized in the NW part of the Central High Atlas (Beni-Mellal/Azilal area). This group is overlain by clays and limestones of the Tillouguite Formation and by Bathonian red beds (silts, sandstones and conglomerates) of the Anemzi Formation. From the Toarcian to Aalenian (Agoudim Members I and II) the contrasting palaeogeographical evolution is marked by a relatively deep central basin bordered by shallow marine carbonates. The Aalenian-Lower Bajocian interval (Agoudim Member II) contains lenticular biodetritic limestones within hemipelagic deposits. These facies resulted from recurrent faulting (tectonic pulses), which was at the origin of the individualization of a series of ridges and depocentres within the High Atlas trough. During the Bajocian (Agoudim Members III and IV) the palaeogeography became homogeneous across the Central High Atlas and corresponded to a carbonate ramp with coral patch reefs. During the ?Late Bajocian (Tazigzaout Lower Member) a new palaeogeography developed with reappearance of the central depocentres. During the latest Bajocian-earliest Bathonian (Tazigzaout Upper Member) a very homogeneous carbonate ramp was again established. These times of uniform palaeogeography are interpreted as relative stable tectonic periods that were progressive stages leading to the ending of the Toarcian-Middle Jurassic sedimentary cycles in the Central High Atlas rift basin of Morocco.

Ait Addi, Abdellah; Chafiki, Driss

2013-08-01

355

Diagenesis and fluid flow in the San Juan Basin, New Mexico - regional zonation in the mineralogy and stable isotope composition of clay minerals in sandstone.  

USGS Publications Warehouse

The Westwater Canyon Member of the Upper Jurassic Morrison Formation is a relatively homogeneous, hydrologically continuous 100-m-thick sequence of massive fluvial sandstone, bounded above and below by relatively heterogeneous, hydrologically discontinuous units and has served as a primary conduit for fluids within this stratigraphic interval. Patterns of mineral-fluid reactions suggest a basinwide hydrologic regime in which warm, evolved fluids migrated up-dip from the center of the basin under the influence of a regional hydraulic head. -from Authors

Whitney, G.; Northrop, H.R.

1987-01-01

356

Total petroleum systems of the Bonaparte Gulf Basin area, Australia; Jurassic, Early Cretaceous-Mesozoic; Keyling, Hyland Bay-Permian; Milligans-Carboniferous, Permian  

USGS Publications Warehouse

The Bonaparte Gulf Basin Province (USGS #3910) of northern Australia contains three important hydrocarbon source-rock intervals. The oldest source-rock interval and associated reservoir rocks is the Milligans-Carboniferous, Permian petroleum system. This petroleum system is located at the southern end of Joseph Bonaparte Gulf and includes both onshore and offshore areas within a northwest to southeast trending Paleozoic rift that was initiated in the Devonian. The Milligans Formation is a Carboniferous marine shale that sources accumulations of both oil and gas in Carboniferous and Permian deltaic, marine shelf carbonate, and shallow to deep marine sandstones. The second petroleum system in the Paleozoic rift is the Keyling, Hyland Bay-Permian. Source rocks include Lower Permian Keyling Formation delta-plain coals and marginal marine shales combined with Upper Permian Hyland Bay Formation prodelta shales. These source-rock intervals provide gas and condensate for fluvial, deltaic, and shallow marine sandstone reservoirs primarily within several members of the Hyland Bay Formation. The Keyling, Hyland Bay-Permian petroleum system is located in the Joseph Bonaparte Gulf, north of the Milligans-Carboniferous, Permian petroleum system, and may extend northwest under the Vulcan graben sub-basin. The third and youngest petroleum system is the Jurassic, Early Cretaceous-Mesozoic system that is located seaward of Joseph Bonaparte Gulf on the Australian continental shelf, and trends southwest-northeast. Source-rock intervals in the Vulcan graben sub-basin include deltaic mudstones of the Middle Jurassic Plover Formation and organic-rich marine shales of the Upper Jurassic Vulcan Formation and Lower Cretaceous Echuca Shoals Formation. These intervals produce gas, oil, and condensate that accumulates in, shallow- to deep-marine sandstone reservoirs of the Challis and Vulcan Formations of Jurassic to Cretaceous age. Organic-rich, marginal marine claystones and coals of the Plover Formation (Lower to Upper Jurassic), combined with marine claystones of the Flamingo Group and Darwin Formation (Upper Jurassic to Lower Cretaceous) comprise the source rocks for the remaining area of the system. These claystones and coals source oil, gas, and condensate accumulations in reservoirs of continental to marine sandstones of the Plover Formation and Flamingo Group. Shales of the regionally distributed Lower Cretaceous Bathurst Island Group and intraformational shales act as seals for hydrocarbons trapped in anticlines and fault blocks, which are the major traps of the province. Production in the Bonaparte Gulf Basin Province began in 1986 using floating production facilities, and had been limited to three offshore fields located in the Vulcan graben sub-basin. Cumulative production from these fields totaled more than 124 million barrels of oil before the facilities were removed after production fell substantially in 1995. Production began in 1998 from three offshore wells in the Zone of Cooperation through floating production facilities. After forty years of exploration, a new infrastructure of pipelines and facilities are planned to tap already discovered offshore reserves and to support additional development.

Bishop, M.G.

1999-01-01

357

Earliest Marine beds in the Jurassic sedimentary record near the Huajuapan-Petlalcingo region, southern Mexico and their paleogeographic implications  

NASA Astrophysics Data System (ADS)

A paleogeographic model of Jurassic-Cretaceous is presented, the study area is the region near Huajuapan de Leon in the Mixteca Terrane, Mexico where a sedimentary successions constituted by interlayered terrestrial and marine beds, provides evidence of transgression and regression episodes. The sediments in the study zone were deposited over a Paleozoic metamorphic basement, the Acatlan Complex. The stratigraphic features in the Middle Jurassic of the terrestrial beds indicate a depositional elements varying from alluvial fans to floodplains and channel deposits, represented by conglomerates, sandy conglomerates and sandstones. After, in the same epoch (Bajocian and Bathonian age) a transgression coming from the Pacific Ocean covered the region. A transitional zone between continental and marine sediments is situated between Tezoatlan and Petlalcingo, the actual cross section consists in the earliest marine beds: limestones interlayered with terrestrial beds. Fossil contents in this beds indicate an age between the Oxfordian and the Tithonian. During this period of transgression the paleogeography was dominated by a small bay with shallow waters connected in the south with the Pacific Ocean, represented principally by limestone and dolomite units. At the end of the transgression, volcanic episodes occurred and the land emerged again. The sedimentary beds were later affected by tectonic activity that produced a normal fault near Zapotitlan, putting the metamorphic basement in contact with the sedimentary sequence.

Contla, D.

2008-12-01

358

Surface energy characterization of sandstone rocks  

NASA Astrophysics Data System (ADS)

The fundamental forces of adhesion are responsible for the spreading of fluids such as crude oil/brine on the reservoir rock surface. These physico-chemical interactions determine the surface energetics of a reservoir and thus their wetting phenomena. Inverse Gas Chromatography (IGC) is introduced to characterize the surface energy of sandstones (Ottawa sand and Berea sandstone). The surface chemistry of the sandstone rocks is further elucidated using X-ray diffraction (XRD) and X-ray Photoelectron Spectroscopy (XPS) techniques. The behavior of the polar and non-polar interaction forces was investigated at varying water coverage and at different temperatures. The results indicated that in general as the water coverage increased, the Lifshitz-van der Waals component of surface energy decreased to nearly that of the bulk water, while the acid-base component also showed a decreasing trend. The Lifshitz-van der Waals component of surface energy always decreased with increase in temperature, while the acid-base properties showed contrasting trends in line with changes in surface chemistry of the sandstones, due to the change in temperature. Finally, the wetting properties arising in reservoir sandstones were related to the surface chemistry of the reservoir fluids and their interactions with the reservoir rock surface.

Arsalan, Naveed; Palayangoda, Sujeewa S.; Burnett, Daniel J.; Buiting, Johannes J.; Nguyen, Quoc P.

2013-08-01

359

Development of risk maps to minimize uranium exposures in the Navajo Churchrock mining district  

PubMed Central

Background Decades of improper disposal of uranium-mining wastes on the Navajo Nation has resulted in adverse human and ecological health impacts as well as socio-cultural problems. As the Navajo people become increasingly aware of the contamination problems, there is a need to develop a risk-communication strategy to properly inform tribal members of the extent and severity of the health risks. To be most effective, this strategy needs to blend accepted risk-communication techniques with Navajo perspectives such that the strategy can be used at the community level to inform culturally- and toxicologically-relevant decisions about land and water use as well as mine-waste remediation. Objective The objective of this study was to develop GIS-based thematic maps as communication tools to clearly identify high risk exposure areas and offer alternatives to minimize public and ecological health impacts. Methods Thematic maps were produced that incorporated data derived from environmental sampling and public health surveys. The maps show the location and quality of unregulated water resources and identify regulated water sources that could be used as alternatives. In addition, the maps show the location of contaminated soil and sediment areas in which disturbance of surface deposits should be avoided. Preliminary feedback was collected from an informal Navajo working group to assess the clarity and efficacy of this proposed communication method. Results The working group found the maps to be both clear and effective, and made suggestions for improvements, such as the addition of more map features. The working group predicted that once the maps are presented to the public, water hauling and soil use behaviors will change, and dialogue with chapter officials will be initiated to accelerate further risk reduction efforts. Implications Because risk communication is complicated by language barriers, lack of infrastructure, and historical mistrust of non-Navajo researchers, mapping provides an easily interpretable medium that can be objectively viewed by community members and decision makers to evaluate activities that affect toxicant exposures. PMID:19589163

2009-01-01

360

Natural gas plays in Jurassic reservoirs of southwestern Alabama and the Florida panhandle area  

SciTech Connect

Three Jurassic natural gas trends can be delineated in Alabama and the Florida panhandle area. They include a deep natural gas trend, a natural gas and condensate trend, and an oil and associated natural gas trend. These trends are recognized by hydrocarbon types, basinal position, and relationship to regional structural features. Within these natural gas trends, at least eight distinct natural gas plays can be identified. These plays are recognized by characteristic petroleum traps and reservoirs. The deep natural gas trend includes the Mobile Bay area play, which is characterized by faulted salt anticlines associated with the Lower Mobile Bay fault system and Norphlet eolian sandstone reservoirs exhibiting primary and secondary porosity at depths exceeding 20,000 ft. The natural gas and condensate trend includes the Mississippi Interior Salt basin play, Mobile graben play, Wiggins arch flank play, and the Pollard fault system play. The Mississippi Interior Salt basin play is typified by salt anticlines associated with salt tectonism in the Mississippi Interior Salt basin and Smackover dolomitized peloidal and pelmoldic grainstone and packstone reservoirs at depths of approximately 16,000 ft. The Mobile graben play is exemplified by faulted salt anticlines associated with the Mobile graben and Smackover dolostone reservoirs at depths of approximately 18,000 ft. The Wiggins arch flank play is characterized by structural traps consisting of salt anticlines associated with stratigraphic thinning and Smackover dolostone reservoirs at depths of approximately 18,000 ft. The Pollard fault system play is typified by combination petroleum traps. The structural component is associated with the Pollard fault system and reservoirs at depths of approximately 15,000 ft. These reservoirs are dominantly Smackover dolomitized oomoldic and pelmoldic grainstones and packstones and Norphlet marine, eolian, and wadi sandstones exhibiting primary and secondary porosity.

Mancini, E.A. (Geological Survey of Alabama, Tuscaloosa (USA) Univ. of Alabama, Tuscaloosa (USA)); Mink, R.M.; Tew, B.H.; Bearden, B.L. (Geological Survey of Alabama, Tuscaloosa (USA))

1990-09-01

361

Main phytostratigraphic boundaries in the Jurassic deposits of Western Siberia  

NASA Astrophysics Data System (ADS)

The study of the large collections of plant remains gained from cores of numerous boreholes drilled in Western Siberia made it possible to determine the taxonomic composition of the Jurassic flora of this region, the stages of its evolution, and the sequence of floral assemblages, which characterize the regional stratigraphic horizons indirectly correlated via series of parallel faunal, microfaunal, spore and pollen zonal scales with a general stratigraphic scale. The compositions of floral assemblages was established in the Hettangian-lower part of the upper Pliensbachian, upper part of the upper Pliensbachian, lower Toarcian, upper Toarcian, Aalenian, Bajocian, Bathonian, and Callovian-Oxfordian sediments. Criteria were elaborated to substantiate the Triassic-Jurassic and Lower-Middle Jurassic boundaries. Lithologically and biostrati-graphically, the Middle-Upper Jurassic boundary is poorly expressed.

Mogutcheva, N. K.

2014-05-01

362

Ch'al Dinek'ehji saad bee'al'ini bini'doonish: dadiits'a'igii doo dabizhi'igii (Frog: Navajo Languages Workbook. Sounds and Symbols).  

ERIC Educational Resources Information Center

Part of the first book series of "Ch'al," the word workbook written in the Navajo language provides supplementary activities to the reading program. Illustrations are in reference to the 11 sound/symbol associations in the Navajo language introduced in the reader-workbook. Illustrated objects are captioned in the Navajo language using diacritical…

Benally, Louise; And Others

363

Thermal Diffusivity of Sandstone Using Photoacoustics  

NASA Astrophysics Data System (ADS)

An open photoacoustic cell was used to investigate the thermal diffusivity of sandstone taken from the Paraná Basin, in Brazil. Although the organic-rich sedimentary rocks represent an important energy source in the Paraná Basin, only limited data are reported concerning their thermophysical properties. A sandstone rock sample, from the Botucatu Formation, was investigated. The thermal diffusivity values were determined with uncertainties around 12 %, comparable to other methods. These values consider not only the experimental errors but also take into account the heterogeneity of the materials. It was possible to verify the behavior of the thermal diffusivity of the sandstone under heat treatment. The variation of the thermal diffusivity followed an expected trend, based on the possible variation of porosity which is related to the decomposition of some constituents. The results presented in this work identify the photoacoustic technique as a useful tool for thermal characterization of sedimentary rocks.

Guimarães, A. O.; de Souza, C. G.; da Silva, E. C.; Soffner, M. E.; Mansanares, A. M.; Ribeiro, H. J. P. S.; Carrasquilla, A. A. G.; Vargas, H.

2015-02-01

364

Chemistry and anelasticity in dehydrated sandstone  

NASA Astrophysics Data System (ADS)

Preliminary acoustic measurements of a dehydrated sample of Berea sandstone indicated a dramatic change in elastic and anelastic properties near 45C. With an improved temperature control system we have characterized the change, a softening of the modulus and an increase in dissipation, in detail. We have attempted to fit a finite-element model of a silica grain-bond network to the data and discuss ideas for the connection between water content and nonlinearity. Berea is a complex sandstone with several components beyond the silica frame, so in order to simplify the sample, we are working with a very nonlinear Fontainebleau sandstone and we present new data from both Nonlinear Resonant Ultrasound Spectroscopy (NRUS) and Dynamic Acoustic Elastic Testing on a dehydrated 99.5% silica rock.

Darling, T. W.; Miller, R. A.

2012-12-01

365

Dakota sandstone facies, western Oklahoma panhandle  

SciTech Connect

The Cretaceous Dakota Sandstone in Cimarron County comprised three sandstone units and intervening mudrocks; it overlies the Kiowa Shale Member of the Purgatoire Formation. Deposits include shoreface, beach (foreshore) and dune, estuarine and tidal channel, marine marginal bay and swamp/marsh in a generally progradational sequences associated with marine regression in the Western Interior. The shoreface sand, characterized by ripple lamination, bioturbation and the trace fossils Teichichnus and Thalassinoides, is fine-grained, 5-10 m (15-30 ft) thick and grades into the underlying Kiowa Shale. Beach and associated dune deposits are 2-5 m (6-16 ft) thick, medium to fine-grained, medium to thick-bedded, tabular-planar cross-bedded, and lenticular; cross-bed paleocurrent headings are northeasterly and northwesterly. Estuarine channel deposits are 3-5 m (10 to 16 ft) thick, trough to tabular-planar cross-bedded, and medium to coarse-grained with local conglomerate overlying the scoured base which commonly cuts into the Kiowa Shale or overlying shoreface sandstone; rip-up clasts and wood pieces are common but trace fossils are rare; southeasterly and southwesterly paleocurrents predominate. Tidal channel deposits are thinner (up to 2 m of 6 ft) and finer grained (medium to fine-grained) that the estuarine channel deposits; they occur within fine-grained sandstone and mudrock sequences, are trough cross-bedded, and commonly contain trace fossils (e.g., Skolithos) and wood fragments. Marine marginal (tidal flat or bay.) deposits comprise fine-grained sandstone, siltstone and interbedded shale, that are 1-3m (3-10 ft) thick with abundant burrows, small ripple marks, and parallel lamination. These grade into the fine to very fine-grained sandstones, siltstones, shales, and coals of the swamp/marsh deposits that are 1-5m (3-16 ft) thick and contain ripple marks, burrows, other trace fossils, and parallel lamination.

Atalik, E.; Mansfield, C.F.

1984-04-01

366

Charters, Constitutions and By-Laws of the Indian Tribes of North America; Part IV: The Southwest (Navajo--Zuni). Occasional Publications in Anthropology Ethnology Series No. 5.  

ERIC Educational Resources Information Center

Part IV of a series of publications consisting of American Indian tribal governmental documents, this volume includes charters, constitutions, articles of association, and by-laws of Indian tribes of New Mexico and Arizona. Documents are included relative to the Navajo Tribe of Arizona and New Mexico; the Eastern Navajo Council--New Mexico; the…

Fay, George E., Comp.

367

He Will Lift Up His Head: A Report to the Developmental Disabilities Office on the Situation of Handicapped Navajos and the Implications Thereof for All Native Americans.  

ERIC Educational Resources Information Center

Issues involved in education of handicapped Navajo children are examined. Background sections contrast the history of treatment for the handicapped in America with the treatment received by handicapped Navajos. Unemployment, substandard housing, lack of accessibility within the reservation, overpopulation, language barriers, and the relationship…

Haskins, James S.; Stifle, J. M.

368

Maternal Mosaicism for a Novel Interleukin2 Receptor ?-Chain Mutation Causing X-Linked Severe CombinedImmunodeficiency in a Navajo Kindred  

Microsoft Academic Search

X-linked severe combined immunodeficiency disease (SCID) results from mutations of IL2RG, the gene encoding the interleukin-2 receptor ? chain, also known as the common ? chain (?c). A distinct form of autosomal recessive SCID occurs at an increased frequency among the Navajo Native American population, The disease gene responsible for autosomal Navajo SCID remains to be determined. We report the

Aengus S. O'Marcaigh; Jennifer M. Puck; Amy E. Pepper; Kenneth De Santes; Morton J. Cowan

1997-01-01

369

Root grooves on sandstone bedrock, Ouachita Mountains  

NASA Astrophysics Data System (ADS)

This study presents findings demonstrating the existence of root grooves on siliceous sandstone. It is clear from biochemical studies that weathering in ecosystems with vigorous plant growth is more rapid than in non-vegetated areas, and previous studies of the interactions between tree roots and bedrock have demonstrated the importance of trees in breaking down bedrock through biophysical and biomechanical processes, including treethrow. However, the development of root grooves has rarely been reported on bedrock other than limestone or calcareous substrate. This poster will show the existence of tree root grooves on siliceous sandstone in the Ouachita Mountains, and will discuss the processes that have led to their genesis and development.

Turkington, A. T.

2010-12-01

370

Triassic/Jurassic faulting patterns of Conecuh Ridge, southwest Alabama  

SciTech Connect

Two major fault systems influenced Jurassic structure and deposition on the Conecuh Ridge, southwest Alabama. Identification and dating of these fault systems are based on seismic-stratigraphic interpretation of a 7-township grid in Monroe and Conecuh Counties. Relative time of faulting is determined by fault geometry and by formation isopachs and isochrons. Smackover and Norphlet Formations, both Late Jurassic in age, are mappable seismic reflectors and are thus reliable for seismicstratigraphic dating. The earlier of the 2 fault systems is a series of horsts and grabens that trends northeast-southwest and is Late Triassic to Early Jurassic in age. The system formed in response to tensional stress associated with the opening of the Atlantic Ocean. The resulting topography was a series of northeast-southwest-trending ridges. Upper Triassic Eagle Mills and Jurassic Werner Formations were deposited in the grabens. The later fault system is also a series of horsts and grabens trending perpendicular to the first. This system was caused by tensional stress related to a pulse in the opening of the Gulf of Mexico. Faulting began in Early Jurassic and continued into Late Jurassic, becoming progressively younger basinward. At the basin margin, faulting produced a very irregular shoreline. Submerged horst blocks became centers for shoaling or carbonate buildups. Today, these blocks are exploration targets in southwest Alabama.

Hutley, J.K.

1985-02-01

371

Jurassic sequence stratigraphy in Mississippi interior salt basin: an aid to petroleum exploration in eastern Gulf of Mexico area  

SciTech Connect

An understanding of sequence stratigraphy of Jurassic units in onshore basins can serve as an aid to identify potential petroleum reservoir and source rocks in the eastern Gulf of Mexico area. Three depositional sequences associated with cycles of eustatic sea level change and coastal onlap have been identified in the Mississippi Interior Salt basin. Three depositional sequences probably correspond to the J2.4, J3.1, and J3.2 sequences of Vail et al for Callovian through Kimmeridgian strata. In the Mississippi Interior salt basin, the lower depositional sequence is bounded by a basal type 2 unconformity and an upper type 2 unconformity in the Callovian. This sequence includes Louann evaporites (transgressive), Pine Hill anhydrites and shales (condensed section), and Norphlet eolian sandstones (highstand regressive). The middle depositional sequence reflects relative sea level rise in the late Callovian. This sequence includes Norphlet marine sandstones and lower Smackover packstones and mudstones (transgressive), middle Smackover mudstones (condensed section), and upper Smackover grainstones and anhydrites (highstand regressive).

Mancini, E.A.; Mink, R.M.; Tew, B.H.

1988-02-01

372

Architectural elements and bounding surfaces in fluvial deposits: anatomy of the Kayenta formation (lower jurassic), Southwest Colorado  

NASA Astrophysics Data System (ADS)

Three well-exposed outcrops in the Kayenta Formation (Lower Jurassic), near Dove Creek in southwestern Colorado, were studied using lateral profiles, in order to test recent regarding architectural-element analysis and the classification and interpretation of internal bounding surfaces. Examination of bounding surfaces within and between elements in the Kayenta outcrops raises problems in applying the three-fold classification of Allen (1983). Enlarging this classification to a six-fold hierarchy permits the discrimination of surfaces intermediate between Allen's second- and third-order types, corresponding to the upper bounding surfaces of macroforms, and internal erosional "reactivation" surfaces within the macroforms. Examples of the first five types of surface occur in the Kayenta outcrops at Dove Creek. The new classifications is offered as a general solution to the problem of description of complex, three-dimensional fluvial sandstone bodies. The Kayenta Formation at Dove Creek consists of a multistorey sandstone body, including the deposits of lateral- and downstream-accreted macroforms. The storeys show no internal cyclicity, neither within individual elements nor through the overall vertical thickness of the formation. Low paleocurrent variance indicates low sinuosity flow, whereas macroform geometry and orientation suggest low to moderate sinuosity. The many internal minor erosion surfaces draped with mud and followed by intraclast breccias imply frequent rapid stage fluctuation, consistent with variable (seasonal? monsonal? ephemmeral?) flow. The results suggest a fluvial architecture similar to that of the South Saskatchewan River, through with a three-dimensional geometry unlike that interpreted from surface studies of that river.

Miall, Andrew D.

1988-03-01

373

Is there a basin-centered gas accumulation in Cotton Valley Group Sandstones, Gulf Coast Basin, U.S.A.?  

USGS Publications Warehouse

The U.S. Geological Survey (USGS), in cooperation with the U.S. Department of Energy, is reevaluating the resource potential of selected domestic basin-centered gas accumulations. Basin-centered gas accumulations are characterized by presence of gas in extensive low-permeability (tight) reservoirs in which conventional seals and trapping mechanisms are absent, abnormally high or low reservoir pressures exist, and gas-water contacts are absent. In 1995, the USGS assessed one basin-centered gas play and two conventional plays within the trend of Jurassic and Cretaceous Cotton Valley Group fl uvial-deltaic and barrierisland/ strandplain sandstones across the onshore northern Gulf of Mexico Basin. Detailed evaluation of geologic and production data provides new insights into these Cotton Valley plays. Two Cotton Valley sandstone trends are identifi ed based on reservoir properties and gas-production characteristics. Transgressive blanket sandstones across northern Louisiana have relatively high porosity and permeability and do not require fracture stimulation to produce gas at commercial rates. South of this trend, and extending westward into eastern Texas, massive sandstones of the Cotton Valley trend exhibit low porosity and permeability and require fracture stimulation. The high permeability of Cotton Valley blanket sandstones is not conducive to the presence of basin-centered gas, but lowpermeability massive sandstones provide the type of reservoir in which basin-centered gas accumulations commonly occur. Data on source rocks, including burial and thermal history, are consistent with the interpretation of potential basincentered gas within Cotton Valley sandstones. However, pressure gradients throughout most of the blanket- and massivesandstone trends are normal or nearly normal, which is not characteristic of basin-centered gas accumulations. The presence of gas-water contacts in at least seven fi elds across the blanket-sandstone trend together with relatively high permeabilities and high gas-production rates without fracture stimulation indicate that fi elds in this trend are conventional. Within the tight massive-sandstone trend, permeability is suffi ciently low that gas-water transition zones are vertically extensive and gas-water contacts either have not been encountered or are poorly defi ned. With increasing depth through these transition zones, gas saturation decreases and water saturation increases until eventually gas saturations become suffi ciently low that, in terms of ultimate cumulative production, wells are noncommercial. Such progressive increase in water saturation with depth suggests that poorly defi ned gas-water contacts probably are present below the depth at which wells become noncommercial. The interpreted presence of gas-water contacts within the tight, Cotton Valley massive-sandstone trend suggests that gas accumulations in this trend, too, are conventional, and that a basin-centered gas accumulation does not exist within Cotton Valley sandstones in the northern Gulf Basin.

Bartberger, Charles E.; Dyman, Thaddeus S.; Condon, Steven M.

2002-01-01

374

Late Jurassic ductile shearing and tectonic breccias in the eastern Great Basin of Nevada and Utah  

SciTech Connect

The Paleozoic sedimentary prism was dismembered in the Late Jurassic by shearing initiated at stratigraphic positions in the following list: (1) base of Meade Peak Shale, (2) base of Summit Springs Evaporites, (3) top of contact Chert Member of the Rib Hill Formation, (4) base of Unit G of the Ely Formation, (5) base of the Ely Limestone, (6) base of the Diamond Peak Sandstone, (7) base of Chainman Shale, (8) base of the Joana Limestone, (9) base of the Pilot Formation, (10) base of Lower Guilmette Limestone, (11) in siltstone at the top of Ely Springs (Hanson Creek) Formation, (12) top and base of the Eureka Quartzite, (13) base of the Dunderberg Shale, and (14) base of Pioche Shale and top of Prospect Mountain Quartzite. The largest are regional decollectments, e.g., Summit Springs, Chainman, Blue Eagle, Silver Island, and Snake Range. The lesser shears vary in position and extent with lithofacies distribution. Shales at all levels behaved ductilely. Carbonates locally behaved ductilely up to the base of the Pilot Formation, but more commonly below the Dunderberg Shale. Brittle deformation in the carbonates produced megatectonic breccias below the shears. These regional breccias became reservoirs for the pore fluids and clay-held fluids expelled from primary source rocks and reservoirs by the dynamic pressures. Igneous plutons injected from 150-30 Ma crosscut and dilated the shear zones, creating hydrothermal systems within the tectonic reservoirs.

Welsh, J.E. Sr. (Natural Resources Geologist, Holladay, UT (United States))

1993-08-01

375

Paleomagnetism of Jurassic volcanic rocks in southeastern Arizona and North American Jurassic apparent polar wander  

SciTech Connect

The Corral Canyon sequence in the Patagonia Mountains is a 650 meter thick homoclinal sequence consisting of interbedded volcaniclastic red-beds, welded ash-flow tuff, and lavas. Rb/Sr isotopic analysis of eight whole rock tuff samples yields an isochron age of 171 +/- 3 Ma. Welded tuffs in the Corral Canyon sequence possess a stable, primary magnetization carried in both magnetite and hematite that defines a paleomagnetic pole at 61.8/sup 0/N, 116.0/sup 0/E. Paleomagnetic study of the Canelo Hills volcanics welded tuff member also yields a stable, primary magnetization throughout a stratigraphic thickness of 600 meters. Various aspects of the paleomagnetic data indicate that discordance of the Canelo Hills volcanics pole is probably due to acquisition of remanent magnetization during a period of non-dipole behavior of the geomagnetic field. Dispersion of paleomagnetic directions suggests that the welded tuff member represents at most two cooling units and can be interpreted as a caldera-fill sequence. A revised Jurassic APW path differs significantly from available paths and has important implications for North American plate motion and paleolatitude. The spatio-temporal progression of reliable Jurassic paleopoles, in conjunction with Triassic and Early Cretaceous poles, is well described by paleomagnetic Euler pole analysis. The APW path is divided into three tracks, separated by two cusps. These cusps represent changes in the direction of North American absolute plate motion and can be correlated with global plate motion and intraplate deformation events at approximately 200-210 Ma and 150 Ma. Finally, the APW path presented herein predicts more southerly Late Triassic and Jurassic paleolatitudes for North America than have been suggested by previous authors.

May, S.R.

1985-01-01

376

Paleozoic to Jurassic terrane accretion along the northeastern margin of Tibet plateau  

NASA Astrophysics Data System (ADS)

The Tibet plateau is considered to have been constructed by a number of basement terranes accreted to the Eurasian margin during Paleozoic to Mesozoic times, and accretion is interpreted to have progressed southwards. The northern margin, exposed in Altyn and Qilian Mountains, is generally considered as an Lower Paleozoic orogen including previously subducted ultra-high successions (Yin and Harrison, 2000; Xiao et al., 2009). Previous tectonic models of the Qaidam block and adjacent mountain ranges at the northeastern margin of the Tibet plateau assumed a minor role of Indosinian tectonism in that region, and firm evidence was only reported from eastern Kunlun Mountains (e.g., Liu et al., 2005). Based on four sources of new data, we propose that the Indosinian tectonism was much more widespread in the northeastern Qaidam block and adjacent mountain ranges, Altyn and Qilian Mts., as believed before and we propose a new tectonic model. The new data sources comprise: (1) 40Ar/39Ar dating of detrital white mica of Jurassic to Pliocene sandstones from the north-eastern Qaidam basin fill; (2) interpretation of Ordovician, Devonian and Jurassic sedimentary successions, from which we interpret the Jurassic successions as intramontane molasse to the Indosinian orogen; (3) 40Ar/39Ar dating of detrital white mica in recent rivers from the southern Qilian Shan revealing possible basement sources in the Qilian Shan draining towards the Qaidam basin; and (4) structural study of basement rocks and subordinate 40Ar/39Ar mineral ages of metamorphic basement rocks. An Ordovician greywacke exposed in the eastern Qaidam basin (W of Delinghua) yields three 40Ar/39Ar age groups of detrital white mica: 900-922, 610-654 and 527-554 Ma. Furthermore, similar old age groups centering at ca. 670 and 1010 Ma are virtually widespread in recent rivers from Qilian Mountains and clearly demonstrate the presence of Panafrican and Grenvillian tectonic elements in the southern Qilian Mts. at the northeastern edge of the Tibetan plateau. This is consistent with scarce reports of U-Pb zircon and Sm-Nd ages from mainly oceanic tectonic elements. Scarce Panafrican ages were also reported from the North Altyn Mountains, too. These units are bordered by a Lower Proterozoic metamorphic and plutonic basement in the north, mainly exposed in the North Altyn Mts, Beishan and North China craton representing a continental microplate separating these units from the Paleozoic Altaids. Our preliminary study of detrital white mica from Eocene to Miocene successions of the northeastern Qaidam basin suggested that a basement with 250 ± 3 and 279 ± 3 Ma must be present in the southern Qilian Shan (Rieser et al., 2007). 40Ar/39Ar dating of detrital white mica from outlets of recent rivers draining into the Qaidam yield following age groups: 190-220 Ma, 240-263 Ma, 310-315 Ma, 400-440 Ma and some values at ca. 1010 Ma. The 190-240 Ma group shows a dominant but slightly younger age as found in our previous study from the Qaidam basin fill and indicate that metamorphic basement successions with late Triassic to earliest Jurassic cooling ages are part of the southern Qilian Shan. These new data gives evidence for the presence of Triassic to Jurassic metamorphic sectors in the southern Qilian Shan and that these units are bordered by a Jurassic basin. The lag time between cooling in the hinterland and deposition in Jurassic basin is low implying rapid exhumation in the hinterland. Based on all these data, we develop a new tectonic model of stepwise accretion of Gondwana-derived units to the northern Lower Proterozoic craton similar as Stampfli and Borel (2002) proposed for the more western Tethysides. Principal age steps of accretion include Late Ordovician-Silurian, Carboniferous and Late Permian-Triassic, the later step also resulting in the final accretion of these units to Eurasia. The Lower Jurassic siliciclastic deposits are thickening towards Qilian Mts. and are interpreted to represent molasse-type deposits to an Indosinian metamorphic element, which exhumed during early

Neubauer, Franz; Liu, Yongjiang; Genser, Johann; Ren, Shoumai

2010-05-01

377

IMPROVING SANDSTONE MATRIX STIMULATION OF OIL  

E-print Network

, Dhahran, Saudi Arabia ABSTRACT Experience has shown that for sandstone formations, oil wells respond to matrix acidizing in a different manner as compared to gas wells. For oil wells, the improvement be improved by displacing the oil in the zone to be treated with gas. Gas injection prior to acid- izing

Abu-Khamsin, Sidqi

378

A Giant Pliosaurid Skull from the Late Jurassic of England  

PubMed Central

Pliosaurids were a long-lived and cosmopolitan group of marine predators that spanned 110 million years and occupied the upper tiers of marine ecosystems from the Middle Jurassic until the early Late Cretaceous. A well-preserved giant pliosaurid skull from the Late Jurassic Kimmeridge Clay Formation of Dorset, United Kingdom, represents a new species, Pliosaurus kevani. This specimen is described in detail, and the taxonomy and systematics of Late Jurassic pliosaurids is revised. We name two additional new species, Pliosaurus carpenteri and Pliosaurus westburyensis, based on previously described relatively complete, well-preserved remains. Most or all Late Jurassic pliosaurids represent a globally distributed monophyletic group (the genus Pliosaurus, excluding ‘Pliosaurus’ andrewsi). Despite its high species diversity, and geographically widespread, temporally extensive occurrence, Pliosaurus shows relatively less morphological and ecological variation than is seen in earlier, multi-genus pliosaurid assemblages such as that of the Middle Jurassic Oxford Clay Formation. It also shows less ecological variation than the pliosaurid-like Cretaceous clade Polycotylidae. Species of Pliosaurus had robust skulls, large body sizes (with skull lengths of 1.7–2.1 metres), and trihedral or subtrihedral teeth suggesting macropredaceous habits. Our data support a trend of decreasing length of the mandibular symphysis through Late Jurassic time, as previously suggested. This may be correlated with increasing adaptation to feeding on large prey. Maximum body size of pliosaurids increased from their first appearance in the Early Jurassic until the Early Cretaceous (skull lengths up to 2360 mm). However, some reduction occurred before their final extinction in the early Late Cretaceous (skull lengths up to 1750 mm). PMID:23741520

Benson, Roger B. J.; Evans, Mark; Smith, Adam S.; Sassoon, Judyth; Moore-Faye, Scott; Ketchum, Hilary F.; Forrest, Richard

2013-01-01

379

Biogeochemistry of the Triassic-Jurassic Boundary  

NASA Astrophysics Data System (ADS)

New biostratigraphic and biogeochemical data are presented from Triassic-Jurassic (Tr-J) boundary sections at Kennecott Point, Queen Charlotte Islands (QCI), Canada, Muller Canyon, Nevada, USA, and Marokopa Beach, New Zealand. The New Zealand record shows two negative excursions in ?13Corg of approximately 2‰ associated with the Tr-J transition. The QCI and Nevada boundary sections show a consistent isotopic trend indicative of multiple major perturbations to the carbon cycle: one negative excursion in ?13Corg of 2‰ at the boundary and one positive excursion of 3 to 5‰ following the boundary. The post-Tr-J boundary positive excursion is especially prominent in boundary sections from QCI, where the high organic content of the black shales makes the rocks suitable for a survey of lipid biomarkers. New GC-MS data are presented from this locality, revealing changes in the distribution and abundance of alkanes, hopanes, and steranes across the Tr-J transition. Litho-, bio- and chemostratigraphy from these boundary localities do not support a single impact cause for the late Triassic extinctions, although impact events such as the Manicouagan may well have exerted significant stress on a biosphere still recovering from the Permian-Triassic mass extinction. The data support the idea of a degraded late Triassic environment persisting for millions of years and characterized by low atmospheric oxygen and high carbon dioxide associated with Central Atlantic Magmatic Province volcanism. Global warming and sea level change may have led to destabilization of seafloor methane hydrates and runaway greenhouse conditions.

Williford, K. H.; Ward, P. D.; Garrison, G. H.

2006-12-01

380

Multistage variable probability forest volume inventory. [the Defiance Unit of the Navajo Nation  

NASA Technical Reports Server (NTRS)

An inventory scheme based on the use of computer processed LANDSAT MSS data was developed. Output from the inventory scheme provides an estimate of the standing net saw timber volume of a major timber species on a selected forested area of the Navajo Nation. Such estimates are based on the values of parameters currently used for scaled sawlog conversion to mill output. The multistage variable probability sampling appears capable of producing estimates which compare favorably with those produced using conventional techniques. In addition, the reduction in time, manpower, and overall costs lend it to numerous applications.

Anderson, J. E. (principal investigator)

1979-01-01

381

Rock-fall Hazard Assessment of the Aspen Forest Trail, Navajo National Monument, Arizona  

NSDL National Science Digital Library

Created by Edwin F. Harp and Gerald F. Wieczorek of the United States Geological Survey (USGS), this resource is an effort to assess the stability of a section of the Aspen Forest Trail to Betatakin Ruins, Navajo National Monument, Arizona, and to discuss methods of remediation and options for reopening the trail. This report includes a description and analysis of the discontinuities that affect slope stability along the trail and recommendations for access to Betatakin Ruins in consideration of the rock-fall hazards. A list of external references is also provided.

Harp, Edwin F.

382

Crossroads and Connections: An Evolving Relationship between NASA and the Navajo Nation  

NASA Astrophysics Data System (ADS)

Is working with Native Americans business as usual? We live in a project-based world that operates on three-to-five-year grants. A long term commitment can be next to impossible to keep, even if you have the best of intentions. Are there things one "must know" before approaching an indigenous population? How is it best to evaluate projects and programs involving Native Americans? In the NASA and the Navajo Nation project, which will turn five in January, 2010, we have compiled some key lessons learned that we hope will inform and encourage future partnerships between the space science education and Native American communities.

Scalice, D.; Carron, A.

2010-08-01

383

Early Jurassic black shales: Global anoxia or regional "Dead Zones"?  

NASA Astrophysics Data System (ADS)

The so-called "Schwarzer Jura" or "Black Jurassic" in Germany is informally used to designate a series of organic-rich sediments that roughly span the Early Jurassic (201.6 - 175.6 Myr), and which culminate in the Toarcian Oceanic Anoxic Event. Based on organic and inorganic geochemical as well as (micro)palaeontological data from several recently drilled cores, black shales deposited directly following the end-Triassic extinction (201.6 Ma) during the Hettangian are extremely similar to Toarcian black shales. Both events are characterized by laminated black shales that contain high amounts of the biomarker isorenieratane, a fossilized pigment derived from green sulphur bacteria. Furthermore, the two intervals show similar changes in phytoplankton assemblages from chromophyte (red) to chlorophyte (green) algae. Combined, the evidence suggests that photic zone euxinia developed repeatedly during the Early Jurassic, making wide swaths of shelf area inhospitable to benthic life. In the oceans today such areas are called "Dead Zones" and they are increasing in number and extent due to the combined effects of man-made eutrophication and global warming. During the Early Jurassic, regional anoxic events developed in response to flood basalt volcanism, which triggered global warming, increased run-off, and changes in ocean circulation. The patchiness of Early Jurassic anoxia allows comparisons to be made with present-day "Dead Zones", while at the same time ocean de-oxygenation in the past may serve to predict future perturbations in the Earth system.

van de Schootbrugge, B.; Payne, J.; Wignall, P.

2012-12-01

384

The Triassic-Jurassic boundary in eastern North America  

NASA Technical Reports Server (NTRS)

Rift basins of the Atlantic passive margin in eastern North America are filled with thousands of meters of continental rocks termed the Newark Supergroup which provide an unprecedented opportunity to examine the fine scale structure of the Triassic-Jurassic mass extinction in continental environments. Time control, vital to the understanding of the mechanisms behind mass extinctions, is provided by lake-level cycles apparently controlled by orbitally induced climate change allowing resolution at the less than 21,000 year level. Correlation with other provinces is provided by a developing high resolution magnetostratigraphy and palynologically-based biostratigraphy. A large number of at least local vertebrate and palynomorph extinctions are concentrated around the boundary with survivors constituting the earliest Jurassic assemblages, apparently without the introduction of new taxa. The palynofloral transition is marked by the dramatic elimination of a relatively high diversity Triassic pollen assemblage with the survivors making up a Jurassic assemblage of very low diversity overwhelmingly dominated by Corollina. Based principally on palynological correlations, the hypothesis that these continental taxonomic transitions were synchronous with the massive Triassic-Jurassic marine extinctions is strongly corroborated. An extremely rapid, perhaps catastrophic, taxonomic turnover at the Triassic-Jurassic boundary, synchronous in continental and marine realms is hypothesized and discussed.

Olsen, P. E.; Comet, B.

1988-01-01

385

Supraregional seismites in Triassic - Jurassic boundary strata  

NASA Astrophysics Data System (ADS)

The end-Triassic mass extinction event (201.564 Ma) was synchronous with the earliest volcanic phase during the emplacement of the Central Atlantic Magmatic Province (CAMP), a large igneous province (LIP) formed during the initial breakup of Pangea. Volcanic degassing of CO2 and other volatile gases, and/or thermogenic methane, from the CAMP is generally regarded as the main cause of the end-Triassic biotic crisis. However, discrepancies in the durations of the ETE (50 Kyrs) and the CAMP volcanism (600 Kyrs) as well as temporal offsets between carbon cycle perturbations and biotic turnovers suggest a more complex scenario that require further studies of the temporal succession of events in Triassic-Jurassic (TJ) boundary strata. Here, we present and examine multiple episodes of soft-sediment deformation (seismite) within uppermost Rhaetian marine and terrestrial strata of Denmark, Sweden and Germany. These seismites are stratigraphically constrained by palynology and C-isotopes to the latest Rhaetian, and are synchronous to the single seismite layer from the UK, which similarly predates the T/J boundary, and has been explained by an extraterrestrial bolide impact. Instead, we argue that the multiple episodes of soft-sediment deformation, interbedded by undisturbed strata, were formed from repeated intense earthquake activity restricted to an interval within the latest Rhaetian bracketed by two negative excursions in ?13C and also containing palynological evidence for deforestation and fern proliferation. The fact that these biotic changes coincide with repeated seismic activity has implications for the end-Triassic extinction and the CAMP scenario. We discuss the temporal position of the seismites in regards to other end-Triassic events, and argue that their supraregional distribution in pre-TJ-boundary strata of NW Europe may be linked to intensified earthquake activity during CAMP emplacement, rather than an extraterrestrial impact.

Lindström, Sofie; Pedersen, Gunver K.; van de Schootbrugge, Bas; Johansson, Leif; Petersen, Henrik I.; Dybkjær, Karen; Weibel, Rikke; Hansen, Katrine H.; Erlström, Mikael; Alwmark, Carl; Nielsen, Lars Henrik; Oschmann, Wolfgang; Tegner, Christian

2014-05-01

386

Strategies for assessing Early{Middle (Pliensbachian{Aalenian) Jurassic cyclochronologies  

Microsoft Academic Search

There are a number of fundamental problems in assessing the astronomically forced cyclostratigraphy of the Jurassic Period. First, Jurassic geochronology is not well constrained, due to a general scarcity of radiometric dates, inferior precision of the existing ones, and large inaccuracies in stratigraphic constraints. These problems are particularly troublesome in the Early to Middle Jurassic cyclic carbonates of the Colle

J. P ark

1999-01-01

387

Middle and upper jurassic depositional environments at outer shelf and slope of Baltimore Canyon Trough  

Microsoft Academic Search

New CDP data acquired in the Baltimore Canyon Trough during project LASE made it possible to map a continuous Jurassic sedimentary sequence from the continental margin to the abyssal plain without interruption by basement structures. Intense carbonate sedimentation is inferred at the outer shelf during the Middle and Late Jurassic. Carbonate sedimentation probably started during the Middle Jurassic with a

L. A. Gamboa; P. L. Stoffa; M. Truchan

1985-01-01

388

Geological Society of America Paleogeographic and tectonic implications of Jurassic sedimentary  

E-print Network

-marine rocks as Jurassic instead of Triassic suggests a period of uplift and erosion or nondeposition extending of Jurassic sedimentary and volcanic sequences in the central Mojave block Elizabeth R. Schermer Department that at least part, and possibly all, of the Fairview Valley For- mation is late Early Jurassic in age. We

Busby, Cathy

389

Geological model of the Jurassic section in the State of Kuwait  

SciTech Connect

Until the end of the seventies, the knowledge of Jurassic Geology in the State of Kuwait was very limited, since only one deep well was drilled and bottomed in the Triassic sediments. Few scattered wells partially penetrated the Jurassic sequence. During the eighties, appreciable number of wells were drilled through the Jurassic, and added a remarkable volume of information. consequently it was necessary to analyze the new data, in order to try to construct a geological model for the Jurassic in the State of Kuwait. This paper includes a number of isopach maps explaining the Jurassic depositional basin which also helps in trying to explain the Jurassic basin in the Arabian Gulf basin. Structural evolution of the Jurassic sequence indicated an inversion of relief when compared with the Cretaceous sequence. In fact, the main Cretaceous arches were sites of sedimentation troughs during the Jurassic period. This fact marks a revolution in the concepts for the Jurassic oil exploration. One of the very effective methods of the definition of the Jurassic structures is the isopaching of the Gotnia Formation. Najmah, Sargelu and Marrat Formations include the main Jurassic reservoirs which were detected as a result of the exploration activities during the eighties. Selective stratigraphic and structural cross sections have been prepared to demonstrate and explain the nature of the Jurassic sediments.

Yousif, S.; Nouman, G.

1995-11-01

390

Occurrence of sauropod dinosaur tracks in the Upper Jurassic of Chile (redescription of Iguanodonichnus frenki)  

E-print Network

Occurrence of sauropod dinosaur tracks in the Upper Jurassic of Chile (redescription studied Upper Jurassic dinosaur unit in South America, the Ban~os del Flaco Formation, Chile. Keywords: Chile; Dinosaur footprints; Parabrontopodus; Sauropod; Upper Jurassic Resu´men En el presente

Benton, Michael

391

Jurassic Chicken: An Avian Bipedal Robot 2001 Florida Conference on Recent Advances in Robotics  

E-print Network

Jurassic Chicken: An Avian Bipedal Robot 2001 Florida Conference on Recent Advances in Robotics May Jurassic Chicken is a whimsically dubbed Master's thesis research platform. Based on avian physiology's researchers have yet applied a neural network to the #12;Page 2/5 Jurassic Chicken: An Avian Bipedal Robot

Schwartz, Eric M.

392

Triassic-Jurassic faunal and floral transition in the Fundy Basin, Nova  

E-print Network

. The Triassic-Jurassic mass extinction may have cleared ecological space for dinosaurian ascent much as the K-T Considered one of the five great mass extinctions of the Phanerozoic, the Triassic- Jurassic event-Jurassic mass extinction include sea-level change and anoxia (Hallam, 1990), a methane- and CO2- generated super

Olsen, Paul E.

393

Preserving Native American petroglyphs on porous sandstone  

USGS Publications Warehouse

A new method of chemical treatment is proposed to improve the durability of soft, porous sandstones onto which Native American petroglyphs have been carved. Cores of Dakota Sandstone from the Faris Cave site, located along the Smoky Hill River in Ellsworth County, Kansas, were treated with ethyl silicate dissolved in a lightweight ketone carrier, and some cores were subsequently treated with a combination of ethyl silicate and silane using the same solvent. Measurement of the resulting physical properties, when compared to untreated cores, indicate the treatments substantially increased the compressive strength and freeze-thaw resistance of the stone without discoloring the stone or completely sealing the pore system. The treatment increases the durability of the stone and provides a method for preserving the petroglyphs at the site. After treating test panels at the site, the petroglyphs were treated in like manner.

Grisafe, D.A.

1996-01-01

394

Increasing Vulnerability to Drought and Climate Change on the Navajo Nation, southwestern United States  

NASA Astrophysics Data System (ADS)

The Navajo Nation of Arizona, New Mexico, and Utah, is an ecologically sensitive semi-arid to arid area where rapid growth of one of the largest population of Native Americans is outstripping the capacity of the land to sustain them. Recent drought conditions, combined with increasing temperatures, are significantly altering the habitability of a region already characterized by harsh living conditions. In addition to altered landscape conditions due to climatic change, drought, and varying land use practices over the last 200 years, the Navajo people have been affected by land use policies and harsh economic conditions that weaken their cultural fabric. Increasing aridity combined with drought threaten the very existence of Navajo culture and the survival of traditional Navajo communities. People presently living on these Native lands are unique in American society as their traditional lifestyle requires intimate knowledge of the ecosystem, knowledge that has been passed on for generations through oral traditions. We present data from the lifelong observations of 73 Native American elders that provide a record of the changes in plants and animals, water availability, weather, and sand or dust storms. This information is used to complement the scant long-term meteorological records and historical documentation for the region to further refine our understanding of the historical trends and local impacts of climate change and drought. Among the most cited changes is a long-term decrease in the amount of annual snowfall over the past century, a transition from wet conditions to dry conditions in the 1940s, and a decline in surface water features. The lack of available water, in addition to changing socioeconomic conditions, was mentioned as a leading cause for the decline in the ability to grow corn and other crops. Other noted changes include the disappearance of springs, and of plant and animal populations (particularly medicinal plants, cottonwood trees, beavers, and eagles). Changes in the frequency of wind, sand and dust storms (more frequent in the 1950s and increasing in the 1990s) were also observed. Important information that cannot be easily gleaned from meteorological and stream flow records are also recorded in our consultations. For example, they include observations of soil moisture and the description of disappearing migratory birds that rely on water sources. Local monitoring of soil moisture conditions today indicates that a rapid decline occurs in the Springtime. The fact that soil moisture was noted in the past to persist through the spring dry season, until the late summer monsoon season has profound implications for impacts to ecosystem viability that may have already occurred with climate change and drought. In addition, these changes in soil moisture also help us understand the mechanisms contributing to current drought severity. We conclude that a long-term drying trend and decreasing snowpack, superimposed on regional drought cycles, will magnify the cultural and literal erosion and desertification of the Navajo Nation and leave its people increasingly vulnerable to climate extremes.

Hiza, M. M.; Kelley, K. B.; Francis, H.

2011-12-01

395

Jurassic faults of southwest Alabama and offshore areas  

SciTech Connect

Four fault groups affecting Jurassic strata occur in the southwest and offshore Alabama areas. They include the regional basement rift trend, the regional peripheral fault trend, the Mobile graben fault system, and the Lower Mobile Bay fault system. The regional basement system rift and regional peripheral fault trends are distinct and rim the inner margin of the eastern Gulf Coastal Plain. The regional basement rift trend is genetically related to the breakup of Pangea and the opening of the Gulf of Mexico in the Late Triassic-Early Jurassic. This fault trend is thought to have formed contemporaneously with deposition of Late Triassic-Early Jurassic Eagle Mills Formation and to displace pre-Mesozoic rocks. The regional peripheral fault trend consists of a group of en echelon extensional faults that are parallel or subparallel to regional strike of Gulf Coastal Plain strata and correspond to the approximate updip limit of thick Louann Salt. Nondiapiric salt features are associated with the trend and maximum structural development is exhibited in the Haynesville-Smackover section. No hydrocarbon accumulations have been documented in the pre-Jurassic strata of southwest and offshore Alabama. Productive hydrocarbon reservoirs occur in Jurassic strata along the trends of the fault groups, suggesting a significant relationship between structural development in the Jurassic and hydrocarbon accumulation. Hydrocarbon traps are generally structural or contain a major structural component and include salt anticlines, faulted salt anticlines, and extensional fault traps. All of the major hydrocarbon accumulations are associated with movement of the Louann Salt along the regional peripheral fault trend, the Mobile graben fault system, or the Lower Mobile Bay fault system.

Mink, R.M.; Tew, B.H.; Bearden, B.L.; Mancini, E.A. (Geological Survey of Alabama, Tuscaloosa (United States))

1991-03-01

396

Constraints on Upper Jurassic palaeogeography in the Ula Gyda trend  

SciTech Connect

BP Norway`s semi-regional 3D database in the Central Trough covers an area of nearly 3000 sq.km. around BP Norway`s two producing fields, Ula and Gyda, and includes strategic acreage within tie-back distance to the fields. Prospectivity in the Ula Gyda trend involves complex salt influenced structures and localized Upper Jurassic depositional systems. The objective of this paper is to demonstrate how the understanding of the semi-regional structures and salt tectonics helped constrain the interpretation of the Upper Jurassic palaeogeography. The control of basement structures (Permian) on cover structures (Upper Jurassic/Base Cretaceous) through Zechstein Salt was interpreted using the 3D semi-regional dataset. Analogue sandbox experiments from the Austin Geodynamics Laboratory provide support for the complex structures which were interpreted on the 3D seismic data. Sandbox models mimic the interpreted monoclinal drape of the Triassic and Jurassic section over the critical basin bounding fault in the Base Zechstein. Structural cells can be identified with the help of the salt isochore. The understanding of the relationship between structural development and salt distribution was a major control on the interpretation. This interpretation coupled with the Upper Jurassic reservoir distribution from well data provided the primary evidence for the gross depositional environment maps which were used in prospect evaluation in the area. 3D visualization and shaded relief displays of the interpreted horizons and isochores played a significant part in developing an understanding of the interplay between the deeper structures and the likely Upper Jurassic palaeogeography and depocentres.

Mundal, I.; Milton, N.; Robinson, N. [BP Norge, Stavanger (Norway)

1995-08-01

397

The Impact of Power Developments on the Navajo Nation. Lake Powell Research Project Bulletin Number 7, April 1975.  

ERIC Educational Resources Information Center

The Federal government and private corporations involved in energy production are placing great emphasis on the strip-mining of vast coal reserves. The Navajo Nation, whose lands contain 20 billion tons of low-sulphur coal, sells vast quantities of its natural resources for use in the urban centers of Arizona and southern California. However, the…

Robbins, Lynn A.

398

25 CFR 161.102 - What notifications are required that tribal laws apply to grazing permits on the Navajo...  

Code of Federal Regulations, 2011 CFR

...What notifications are required that tribal laws apply to grazing permits on the Navajo...LANDS GRAZING PERMITS Tribal Policies and Laws Pertaining to Permits § 161.102 What notifications are required that tribal laws apply to grazing permits on the...

2011-04-01

399

Bayesian models for elevated disease risk due to exposure to uranium mine and mill waste on the Navajo Nation  

E-print Network

ForReview Only Bayesian models for elevated disease risk due to exposure to uranium mine and mill of Pharmacy, Community Environmental Health Program Keywords: abandoned uranium mines, conditionally specified to ex- posure to uranium mine and mill waste on the Navajo Nation Glenn A. Stark University of New

Huerta, Gabriel

400

78 FR 2685 - Notice of Intent To Prepare a Programmatic Environmental Impact Statement (EIS) for the Navajo...  

Federal Register 2010, 2011, 2012, 2013, 2014

...Programmatic Environmental Impact Statement (EIS) for the Navajo Nation Integrated Weed...cooperating agencies, intends to prepare an EIS for a proposed weed management plan for...DATES: Comments on the scope of the EIS may be submitted in writing until...

2013-01-14

401

A Study of Navajo Perceptions of the Impact of Environmental Changes Relating to Energy Resource Development. Final Report.  

ERIC Educational Resources Information Center

Ethnographic interview methods were utilized to determine the social costs of energy development (i.e. uranium mining) and the mitigation of these costs. Determination was made from the viewpoint of the Navajos in the Burnhams Chapter (a geopolitical unit) in Western New Mexico; they anticipated four major costs (losses) to their present way of…

Schoepfle, G. Mark; And Others

402

Navajo Environmental Health Review by the National Environmental Health Association (Window Rock, Arizona, May 24-27, 1976).  

ERIC Educational Resources Information Center

The Indian Health Committee met with key staff of the Indian Health Service (IHS) Area Office to review the environmental health services provided on the Navajo Reservation and make recommendations for improvement or expansion of current programs, if needed. Recommendations were made regarding environmental health and institutional personnel,…

Navajo Health Authority, Window Rock, AZ.

403

The Potential of Local Farming on the Navajo Nation to Improve Fruit and Vegetable Intake: Barriers and Opportunities  

Microsoft Academic Search

American Indian populations have low produce intake compared to other ethnic groups and higher rates of diet-related chronic diseases. Programs linking farmers to their community (Farm-to-Table) are an innovative way to alter the food environment. We interviewed Navajo farmers (n = 20), storeowners (n = 7), and non-governmental organization representatives (n = 4) to better understand local farming practices and

Ashley Setala; Sara N. Bleich; Kristen Speakman; Jane Oski; Tammy Martin; Regina Moore; Marcella Tohannie; Joel Gittelsohn

2011-01-01

404

Examining the Lives of Navajo Native American Teenage Mothers in Context: A 12- to 15-Year Follow-Up  

ERIC Educational Resources Information Center

In 1992 and 1995, data were collected from 29 Navajo, reservation-residing teenage mothers. In 2007, follow-up data from 69% (n = 20) of the original sample were collected. Intensive interviews, grounded in ecological systems theory (U. Bronfenbrenner, 1989), allowed for contextual examination of the women's developmental trajectories. Significant…

Dalla, Rochelle L.; Jacobs-Hagen, Susan B.; Jareske, Betsy K.; Sukup, Julie L.

2009-01-01

405

Mother, Daughter, Teenager—Who Am I?Perceptions of Adolescent Maternity in a Navajo Reservation Community  

Microsoft Academic Search

Intensive interviews focusing on perceptions of teenage parenting were conducted with Navajo teenage mothers, their mothers, and community informants. Data analyses revealed 2 central themes representing commitment to maternity or adolescence. Integration of these central themes resulted in a framework depicting four categories representing (a) teenagers highly committed to maternity and adolescence, (b) those identifying primarily with adolescence, (c) teenagers

ROCHELLE L. DALLA; WENDY C. GAMBLE

2000-01-01

406

Navajo Code Talker Joe Morris, Sr. shared insights from his time as a secret World War Two messenger  

NASA Technical Reports Server (NTRS)

Navajo Code Talker Joe Morris, Sr. shared insights from his time as a secret World War Two messenger with his audience at NASA's Dryden Flight Research Center on Nov. 26, 2002. NASA Dryden is located on Edwards Air Force Base in California's Mojave Desert.

2002-01-01

407

Unified Mathematics: Scope, Sequence, and Goals for the Three-Year Curriculum of the Navajo Mission/Academy, Farmington, NM.  

ERIC Educational Resources Information Center

Beginning with the 1980-81 school year, the Navajo Mission/Academy implemented a new secondary school mathematics curriculum, Unified Mathematics, based on New York State's "Three-Year Sequence for High School Mathematics." The comprehensive package meets the school's 3-year mathematics graduation requirement and provides preparation for…

Frank, K. W.

408

25 CFR 161.102 - What notifications are required that tribal laws apply to grazing permits on the Navajo...  

Code of Federal Regulations, 2013 CFR

...What notifications are required that tribal laws apply to grazing permits on the Navajo...LANDS GRAZING PERMITS Tribal Policies and Laws Pertaining to Permits § 161.102 What notifications are required that tribal laws apply to grazing permits on the...

2013-04-01

409

Trace fossil assemblages in selected shelf sandstones  

E-print Network

IN DELTA AND DELTA MARGIN FACIES Introduction Coyote Creek Lone Pine Field Summary TRACE F'OSSILS IN SELECTED SHELF FACIES Introduction Sacatosa Recluse Field Dos Arroyos Field House Creek Field Dlmitos Ranch Kurten Field East Binger Field..., Alpine Parker 2, Recluse Field, Wyoming (D-0) Trace fossils present and log responses of the San Miguel Sandstone, Endeavor-Steeger Halsell 1-112, Sacatosa area, Texas. The size of the bars denotes the relative abundance of the trace fossils repre...

Locke, Kathleen Ann

1983-01-01

410

Alkali solution treatment on sandstone cores  

E-print Network

in the vicinity of the producing wells during injection of alkaline water. The object of this research is to develop a technique to increase the permeability of shaly sandstone by injecting sodium hydroxide solution. In addition, information that is developed... needed by the nation is being supplied by the oil exporting countries. Thus, a technique is needed that can increase the productivity of oil wells so that dependence on foreign oil can be reduced. At the present time hydraulic fracturing is the chief...

Lee, Suk Jin

1978-01-01

411

The Batá Formation of Colombia is truly Cretaceous, not Jurassic  

NASA Astrophysics Data System (ADS)

The Batá Formation has been a key unit in paleogeographic reconstructions of Colombia since it was first described as a Jurassic unit. However, the paleontologic evidence for this age was not beyond doubt. The trigoniids collected from the upper part of the unit were misidentified and should be referred to the late late Jurassic-early Cretaceous genus Syrotrigonia. On palynomorph evidence, the Interulobites triangularis, Cyclusphaera psilata, Classopolis, and Balmeiopsis limbatus assemblage indicates that the section should be late Valanginian-Hauterivian in age.

Serna, F. Etayo; Solé De Porta, N.; De Porta, J.; Gaona, T.

2003-07-01

412

The second Jurassic dinosaur rush and the dawn of dinomania.  

PubMed

During the second Jurassic dinosaur rush museum paleontologists raced to display the world's first mounted sauropod dinosaur. The American Museum of Natural History triumphed in 1905 when its Brontosaurus debuted before an admiring crowd of wealthy New Yorkers. The Carnegie Museum of Natural History in Pittsburgh, the Field Columbian Museum in Chicago and other institutions were quick to follow with their own sauropod displays. Thereafter, dinomania spread far and wide, and big, showpiece dinosaurs became a museum staple. This brief but intensely competitive period of acquisitiveness fostered important Jurassic dinosaur revisions and crucial innovations in paleontological field and lab techniques. PMID:20667597

Brinkman, Paul D

2010-09-01

413

Combined single-grain (U-Th)\\/He and U\\/Pb dating of detrital zircons from the Navajo Sandstone, Utah  

Microsoft Academic Search

Radioisotopic dating of detrital minerals in sedimentary rocks can constrain sediment sources (provenance), elucidate episodes and rates of ancient orogenesis, and give infor- mation on paleogeography and sediment-dispersal patterns. Previous approaches have been restricted to the application of a single technique, such as U\\/Pb or fission-track dating, to detrital grains. These methods provide crystallization and cooling ages, respec- tively, of

Jeffrey M. Rahl; Peter W. Reiners; Ian H. Campbell; Stefan Nicolescu; Charlotte M. Allen

2003-01-01

414

Progressive evolution of deformation band populations during Laramide fault-propagation folding: Navajo Sandstone, San Rafael monocline, Utah, U.S.A.  

NASA Astrophysics Data System (ADS)

Monoclinal fault propagation folds are a common type of structure in orogenic foreland settings, particularly on the Colorado Plateau. We have studied a portion of the San Rafael monocline, Utah, assumed to have formed through pure thrust- or reverse-slip (blind) fault movement, and mapped a particular sequence of subseismic cataclastic deformation structures (deformation bands) that can be related in terms of geometry, density and orientation to the dip of the forelimb or fold interlimb angle. In simple terms, deformation bands parallel to bedding are the first structures to form, increasing exponentially in number as the forelimb gets steeper. At about 30° rotation of the forelimb, bands forming ladder structures start to cross-cut bedding, consolidating themselves into a well-defined and regularly spaced network of deformation band zones that rotate with the layering during further deformation. In summary, we demonstrate a close relationship between limb dip and deformation band density that can be used to predict the distribution and orientation of such subseismic structures in subsurface reservoirs of similar type. Furthermore, given the fact that these cataclastic deformation bands compartmentalize fluid flow, this relationship can be used to predict or model fluid flow across and along comparable fault-propagation folds.

Zuluaga, Luisa F.; Fossen, Haakon; Rotevatn, Atle

2014-11-01

415

Jurassic deep-water fans in the Neo-Tethys Ocean: The Kashafrud Formation of the Kopet-Dagh Basin, Iran  

NASA Astrophysics Data System (ADS)

The Middle Jurassic Kashafrud Formation of northeast Iran was deposited in the Kopet-Dagh Basin, linked to the Neo-Tethys Ocean. The 2 km thick succession commences with fluvio-marine boulder conglomerates that occupy bedrock valleys, but the bulk of the formation comprises a deep-water succession of interbedded sandstone and mudstone packages with trace fossils and sparse ammonites. Neogene collisional events deformed the strata to create the Kopet-Dagh mountains. The deep-water succession represents channel-lobe systems and associated levees and overbank areas on slope to basin-floor fans. Northward paleoflow suggests that rivers drained uplands along the Paleo-Tethys Suture zone, forming fan deltas on a narrow shelf, with associated sediment transport to deeper water. Coarse sands, extrabasinal pebbles, and plant fragments are present throughout the formation, and a thick boulder conglomerate unit lies within the turbidite succession. These observations suggest proximity to terrestrial sources throughout deposition. Sandstone packages are mainly less than 10 m thick (maximum 84 m), and numerous lensoid packages of thick-bedded sandstone tens of meters thick and up to 200 m wide represent submarine channel fills. Thick-bedded lenses and sheets show a relatively narrow range of paleoflow direction and represent major submarine conduits, whereas the more varied paleoflow direction of thin-bedded packages suggests that many were deposited on levees. The presence in the Kashafrud Formation of potential source rocks in the form of organic-rich mudstones and abundant plant fragments suggests that the formation may have contributed to hydrocarbon fields within overlying formations. Sandstone sheets and channel fills could form local reservoirs.

Poursoltani, Mehdi Reza; Moussavi-Harami, Reza; Gibling, Martin R.

2007-05-01

416

Apatite Fission-Track Analysis of the Middle Jurassic Todos Santos Formation from Chiapas, Mexico.  

NASA Astrophysics Data System (ADS)

The Sierra de Chiapas (SCH), located in the south of Mexico, is a complex geological province that can be divided on four different lithological or tectonic areas: (1) the Chiapas Massif Complex (CMC); (2) the Central Depression; (3) the Strike-slip Fault Province, and (4) the Chiapas Fold-and-thrust Belt. The CMC mostly consists of Permian granitoids and meta-granitoids, and represents the basement of the SCH. During the Jurassic period red beds and salt were deposited on this territory, related to the main pulse of rifting and opening of the Gulf of Mexico. Most of the Cretaceous stratigraphy contains limestones and dolomites deposited on a marine platform setting during the postrift stage of the Gulf of Mexico rift. During the Cenozoic Era took place the major clastic sedimentation along the SCH. According the published low-temperature geochronology data (Witt et al., 2012), SCH has three main phases of thermo-tectonic history: (1) slow exhumation between 35 and 25 Ma, that affected mainly the basement (CMC) and is probably related to the migration of the Chortís block; (2) fast exhumation during the Middle-Late Miocene caused by strike-slip deformation that affects almost all Chiapas territory; (3) period of rapid cooling from 6 to 5 Ma, that affects the Chiapas Fold-and-thrust Belt, coincident with the landward migration of the Caribbean-North America plate boundaries. The two last events were the most significant on the formation of the present-day topography of the SCH. However, the stratigraphy of the SCH shows traces of the existence of earlier tectonic events. This study presents preliminary results of apatite fission-track (AFT) dating of sandstones from the Todos Santos Formation (Middle Jurassic). The analyses are performed with in situ uranium determination using LA-ICP-MS (e.g., Hasebe et al., 2004). The AFT data indicate that this Formation has suffered high-grade diagenesis (probably over 150 ºC) and the obtained cooling ages, about 70-60 Ma, correspond to a Late Cretaceous event. This tectonic event is contemporaneous with a startup of the Laramide Orogeny occurred in North America. The constructed time-temperature paths show the rapid cooling during the Middle-Late Miocene (15-10 Ma), like other published data. References: Hasebe et al. (2004) Chemical Geology, 207, 135-145 Witt et al. (2012) Tectonics, 31, TC6001, doi:10.1029/2012TC003141

Abdullin, Fanis; Solé, Jesús; Shchepetilnikova, Valentina; Solari, Luigi; Ortega-Obregón, Carlos

2014-05-01

417

The "van Zijl" Jurassic geomagnetic reversal revisited  

NASA Astrophysics Data System (ADS)

In 1962, van Zijl and colleagues published the first record of one of the oldest reversals available in some detail. This was a Jurassic reversal recorded in the basaltic sequence of the Lesotho, part of the Karoo large igneous province. In 2003, Prévot and colleagues provided a second more accurate record (Bushmen's Pass section - BP). We have recently obtained two other detailed records from two sections (Naude's Nek NN and Oxbow-Moteng Pass OM). The reversal is therefore now recorded in some detail in three sections which are up to 200km away from each other (the age being at ~180Ma). The reversal is recorded as 23 transitional directions over 130m in NN. When lava flows having recorded the (statistically) same direction to within a few degrees, which likely belong to the same cooling unit, are regrouped (directional groups or DG), we are left with 10 independent directions. There are 13 transitional directions over 160m in OM, and 8 distinct, independent directions. And in the BP section, there are 35 transitional directions over 200m, and 21 independent directions. The three records are remarkably similar and at the same time complementary. They can be used to retrace the VGP reversal path in a unique and robust way. Directions display 4 strong clusters which are interpreted as times of slow secular variation and/or fast extrusion rate of the lava. The path jumps from transitional reversed to transitional normal directions with no intermediate directions between 30°S and 30°N (once the path has been restored to proper geographical coordinates applicable to the ~180Ma reconstruction of the continents). We have applied several techniques to determine the evolution of relative paleo-intensities during the reversal; all these methods converge to the same conclusion, with intensities lower by a factor close to 10 between the core of the reversal and the time when full normal polarity has been regained, with intermediate intensities just before and after the core of the reversal. These observations are consistent with fast and large secular variation at a time when field intensity was the weakest and field geometry the least dipolar. The question which remains is how complete is this record? At the same time, the fact that it has been recorded in such a consistent way in three very remote sections would argue in favor of a positive answer, though the large extent and volume of Karoo cooling units may argue to the contrary...

Courtillot, V.; Moulin, M.; fluteau, F.; Valet, J. M.

2011-12-01

418

INVESTIGATION OF THE GEOMAGNETIC FIELD POLARITY DURING THE JURASSIC  

Microsoft Academic Search

A large number of sedimentary rock formations on the Colorado Plateau and in the Wyoming foreland have been investigated paleo- magnetically in an attempt to determine the geo- magnetic polarity during the Middle and the ear- ly Late Jurassic, a period frequently postulated to have been of constant normal polarity. A sur- vey of published paleomagnetic litature shows this postulate

Maureen B. Steiner

1980-01-01

419

Stratigraphy of the Jurassic system in northern Egypt  

SciTech Connect

A regional synthesis is presented of the stratigraphy of Jurassic strata in Egypt north of 30/degree/N, based on the study of about 80 wells and outcrops from northeastern Egypt. Almost all fossil groups have been investigated for biostratigraphic control. Published work on ammonite faunas from Gebel el Maghara (north Sinai) is integrated with extensive original work on palynofloras (and, to a lesser extent, ostracod/foraminiferal faunas) recovered from marine rocks in the subsurface. The recovery of rich dinocyst assemblages enables the recognition of a ten-fold zonation scheme, largely within the Middle-Late Jurassic sedimentary package. The upper limit of this package is marked by the Cimmerian erosional event; strata younger than Oxfordian are rarely preserved. Only east of 30/degree/E is significant sedimentation known to have occurred immediately prior to the major early Bajocian transgressive event. Thereafter mean sea level rose steadily. The Lower Triassic-Lower Jurassic sedimentary package is poorly understood, largely the result of scanty and ambiguous stratigraphic evidence. However, regional correlations suggest that only very thin earliest Jurassic (Hettangian ) clastic deposition succeeded a sequence of Upper Triassic carbonates and evaporites (Wadi en Natrun Formation) in the north. Arising from these studies is a standard lithostratigraphical scheme. The upper sedimentary package, the Gebel el Maghara Group, comprises three formations (Masajid, Khatatba, and Inmar) and seven members; new units are defined and old units redefined.

Keeley, M.L.; Shaw, D.; Forbes, G.A.

1988-08-01

420

Jurassic epithermal Au–Ag deposits of Patagonia, Argentina  

Microsoft Academic Search

Important precious metal deposits have been discovered during the last 10 years in the Deseado Massif region of Patagonia, Argentina. This region is a plateau consisting of Middle to Upper Jurassic volcanic rocks that host fracture-controlled epithermal Au–Ag mineralization. These mineral deposits represent low sulfidation type hydrothermal systems and formed following the main period of volcanism, probably during the Late

I. B Schalamuk; M Zubia; A Genini; R. R Fernandez

1997-01-01

421

Let the Volgian stage stay in the Jurassic  

Microsoft Academic Search

In 1996 the Volgian Stage was divided into the Jurassic and Cretaceous units, removed from the Geological Time Scale, and substituted by the Tithonian Stage according to the guidelines of the Interdepartmental Stratigraphic Committee of the Russian Federation (ISC RF). Consequently, the Upper Volgian Substage including three zones (five subzones) was placed into the Berriasian Stage (the Cretaceous) proceeding from

V. A. Zakharov; M. A. Rogov

2008-01-01

422

TRIASSIC AND JURASSIC FORMATIONS OF THE NEWARK BASIN  

E-print Network

TRIASSIC AND JURASSIC FORMATIONS OF THE NEWARK BASIN PAUL E. OLSEN Bingham Laboratories, Department of Biology, Yale University, New Haven, Connecticut Abstract Newark Supergroup deposits of the Newark Basin (or lack thereof). Fossils are abundant in the sedimentary formations of the Newark Basin and provide

Olsen, Paul E.

423

JURASSIC CYCLOSTRATIGRAPHY AND PALEONTOLOGY OF THE HARTFORD BASIN  

E-print Network

A4-1 JURASSIC CYCLOSTRATIGRAPHY AND PALEONTOLOGY OF THE HARTFORD BASIN by Paul E. Olsen and Jessica rift basin (Figs. 1, 2) are profoundly cyclical. Interbedded with the three laterally extensive basalt-central Hartford basin. We use the permeating Milankovitch cyclostratigraphy as the basis for an astronomically

Olsen, Paul E.

424

Exploration in Jurassic of North Mafla, eastern Gulf of Mexico  

Microsoft Academic Search

Exploration in North Mafla focuses on general categories of prospects, potential reservoirs and their associated facies, and seismic modeling of available well control. Jurassic prospects in North Mafla can be classified into four general categories: (1) basement-related structures: (2) closures associated with the Pensacola-Destin peripheral fault trend, (3) salt anticlines, and (4) prospects associated with the interregional structural highs. Each

Kemmer

1987-01-01

425

Jurassic igneous-related metallogeny of southwestern North America  

E-print Network

, and vein Cu(±Au±Ag±Mo±Zn±Pb±Ag) systems; (2) IOCG (Fe oxide-Cu-Au) vein, breccia and skarn systems; (3) VMS. Hydrothermal systems are numerous and varied, al- though fewer major mineral deposits are known than with later, the Jurassic contains few epithermal and lithophile element deposits. Multiple factors contributed

Barton, Mark D.

426

Latest Jurassic-early Cretaceous regressive facies, northeast Africa craton  

Microsoft Academic Search

Nonmarine to paralic detrital deposits accumulated in six large basins between Algeria and the Arabo-Nubian shield during major regression in latest Jurassic and Early Cretaceous time. The Ghadames Sirte (north-central Libya), and Northern (Egypt) basins lay along the cratonic margin of northeastern Africa. The Murzuk, Kufra, and Southern (Egypt) basins lay in the south within the craton. Data for reconstructing

van Houten

1980-01-01

427

57 Fe Mössbauer and X-ray characterisation of sandstones  

NASA Astrophysics Data System (ADS)

Sandstones from the Free State province in South Africa have been mined and processed mainly by small scale and artisanal miners in the rural areas. In the present investigation basic fire proof and water absorption tests, X-ray and ?-ray based characterisation techniques were used to study the sandstones. The collected samples were grouped according to their apparent colour in day light conditions and the elemental analysis showed the presence of a high amount of oxygen (>52%) and silicon (>38%) with Mn, Al, Fe and Ca as major elements in proportions related to the colour distribution of the various sandstones. The uniaxial compressive stress was found to be the highest (56 MPa) for the greyish sandstone and the lowest (8 MPa) for the white sandstone sample, also associated with the lowest (Al+Fe)/Si value of 0.082. The humidity test showed that the 6 % water absorption was lower than the recommended ASTM value of 8 %. The sandstone samples were also subjected to various high temperatures to simulate possible fire conditions and it was found that the non alteration of the mineral species might be one of the reasons why the sandstones are regarded as the most refractory amongst the building materials typically used. Mössbauer spectroscopy revealed that iron is present in all the sandstones, mainly as Fe3 + with the black sandstone showing an additional presence of 3 % Fe2 + indicating that a higher iron content coupled to higher silicon content, contributes to an increase in the uniaxial compressive strength.

Mulaba-Bafubiandi, A. F.; Waanders, F. B.

2013-04-01

428

Comparison of geology of Jurassic Norphlet Mary Ann field, Mobile Bay, Alabama, to onshore regional Norphlet trends  

SciTech Connect

The geology of the Mary Ann field is better understood in light of regional studies, which help to establish a depositional model in terms of both facies and thickness variations. These studies also illustrate major differences between onshore and offshore Norphlet deposits concerning topics such as diagenesis, hydrocarbon trapping, and migration. The Jurassic Norphlet sandstone was deposited in an arid basin extending from east Texas to Florida by a fluvial-eolian depositional system, prior to the transgression of the Smackover Formation. Until discovery of the Mary Ann field in 1979, Norphlet production was restricted to onshore areas, mostly along the Pickens-Pollard fault system in Mississippi, Alabama, and Florida. The Mary Ann field is a Norphlet dry-gas accumulation, and was the first offshore field in the Gulf of Mexico to establish economic reserves in the Jurassic. The field is located in Mobile Bay, approximately 25 mi (40 km) south of Mobile, Alabama. Formed by a deep-seated (more than 20,000 ft or 6096 m) faulted salt pillow, Mary Ann field produces from a series of stacked eolian dune sands situated near the Norphlet paleocoastline. Five lithofacies have been recognized in cores from the Mobil 76 No. 2 well. Each lithofacies has a distinct reservoir quality. Optimum reservoir faces are the dune and sheet sands. Nonreservoir facies are interdune (wet and dry), marine reworked, and evaporitic sands. Following deposition, these sediments have undergone varying amounts of diagenesis. Early cementation of well-sorted sands supported the pore system during compaction. However, late cementation by chlorite, silica, and alteration of liquid hydrocarbons to an asphaltic residue have completely occluded the pore system in parts of the reservoir.

Marzono, M.; Pense, G.; Andronaco, P.

1988-09-01

429

Paleomagnetism of the Middle-Late Jurassic to Cretaceous red beds from the Peninsular Thailand: Implications for collision tectonics  

NASA Astrophysics Data System (ADS)

Jurassic to Cretaceous red sandstones were sampled at 33 sites from the Khlong Min and Lam Thap formations of the Trang Syncline (7.6°N, 99.6°E), the Peninsular Thailand. Rock magnetic experiments generally revealed hematite as a carrier of natural remanent magnetization. Stepwise thermal demagnetization isolates remanent components with unblocking temperatures of 620-690 °C. An easterly deflected declination ( D = 31.1°, I = 12.2°, ?95 = 13.9°, N = 9, in stratigraphic coordinates) is observed as pre-folding remanent magnetization from North Trang Syncline, whereas westerly deflected declination ( D = 342.8°, I = 22.3°, ?95 = 12.7°, N = 13 in geographic coordinates) appears in the post-folding remanent magnetization from West Trang Syncline. These observations suggest an occurrence of two opposite tectonic rotations in the Trang area, which as a part of Thai-Malay Peninsula received clockwise rotation after Jurassic together with Shan-Thai and Indochina blocks. Between the Late Cretaceous and Middle Miocene, this area as a part of southern Sundaland Block experienced up to 24.5° ± 11.5° counter-clockwise rotation with respect to South China Block. This post-Cretaceous tectonic rotation in Trang area is considered as a part of large scale counter-clockwise rotation experienced by the southern Sundaland Block (including the Peninsular Malaysia, Borneo and south Sulawesi areas) as a result of Australian Plate collision with southeast Asia. Within the framework of Sundaland Block, the northern boundary of counter-clockwise rotated zone lies between the Trang area and the Khorat Basin.

Yamashita, Itaru; Surinkum, Adichat; Wada, Yutaka; Fujihara, Makoto; Yokoyama, Masao; Zaman, Haider; Otofuji, Yo-ichiro

2011-02-01

430

Hydrocarbon potential of a new Jurassic play, central Tunisia  

SciTech Connect

A largely unrecognized Jurassic Sag Basin has been identified in central Tunisia, proximal to the Permo-Carboniferous flexure delineating the northern boundary of the Saharan platform of north Africa. The northwestern margin of the Sag is delineated by an extensive region of salt-cored anticlines and localized salt diapirs extending north and west. Due to lack of deep drilling, delineation of the Sag is largely based on regional gravity data. Subsidence of the Jurassic Sag Basin is characterized by rapid expansion of Jurassic sediments from 400 m. of tidal flat and shelf carbonate at the western outcrop to over 2000 meters of tidal flat and basinal carbonate and shale within the basin center, a five-fold expansion. Rapid loading of the basin continued into Lower Cretaceous time, marked by lateral flowage of Triassic salt into pronounced structural trends. Published source rock data and interpreted subsurface well data provided the basis for GENEX 1-D hydrocarbon generation and expulsion modeling of the Sag. Middle Jurassic black source shales typically contain Type II and Type III kerogens with T.O.C.'s ranging up to 4 percent. Modeling results indicate that middle Jurassic shales are presently mature for liquid generation within portions of the Sag, with maximum generation taking place during the Tertiary. Potential hydrocarbon generation yields, based on 60 meters of mature source shale, are 20,000 BOE/acre for gas and 75,000 BOE/acre for liquids. Prospects within the region could contain an estimated potential reserve of several T.C.F. or over 1 billion barrels of oil.

Beall, A.O. (Arthur O. Beall International E P, Houston, TX (United States)); Law, C.W. (Geomath, Houston, TX (United States))

1996-01-01

431

Hydrocarbon potential of a new Jurassic play, central Tunisia  

SciTech Connect

A largely unrecognized Jurassic Sag Basin has been identified in central Tunisia, proximal to the Permo-Carboniferous flexure delineating the northern boundary of the Saharan platform of north Africa. The northwestern margin of the Sag is delineated by an extensive region of salt-cored anticlines and localized salt diapirs extending north and west. Due to lack of deep drilling, delineation of the Sag is largely based on regional gravity data. Subsidence of the Jurassic Sag Basin is characterized by rapid expansion of Jurassic sediments from 400 m. of tidal flat and shelf carbonate at the western outcrop to over 2000 meters of tidal flat and basinal carbonate and shale within the basin center, a five-fold expansion. Rapid loading of the basin continued into Lower Cretaceous time, marked by lateral flowage of Triassic salt into pronounced structural trends. Published source rock data and interpreted subsurface well data provided the basis for GENEX 1-D hydrocarbon generation and expulsion modeling of the Sag. Middle Jurassic black source shales typically contain Type II and Type III kerogens with T.O.C.`s ranging up to 4 percent. Modeling results indicate that middle Jurassic shales are presently mature for liquid generation within portions of the Sag, with maximum generation taking place during the Tertiary. Potential hydrocarbon generation yields, based on 60 meters of mature source shale, are 20,000 BOE/acre for gas and 75,000 BOE/acre for liquids. Prospects within the region could contain an estimated potential reserve of several T.C.F. or over 1 billion barrels of oil.

Beall, A.O. [Arthur O. Beall International E& P, Houston, TX (United States); Law, C.W. [Geomath, Houston, TX (United States)

1996-12-31

432

Jurassic paleopole controversy: Contributions from the Atlantic-bordering continents  

NASA Astrophysics Data System (ADS)

The Early-early Middle Jurassic and Early Cretaceous mean paleopoles for North America, Europe, South America, and Africa are very well grouped in appropriate continental reconstructions, but the intervening late Middle and Late Jurassic segment of the apparent polar wander path (APWP) is poorly defined and controversial. The available paleopoles, reconstructed for the partial opening of the central Atlantic Ocean, form a scattered grouping with no coherent age patterns, illustrating that they do not constitute a robust data set. Uncertainties in the reconstruction parameters between North America and Europe also play a role. However, excellent paleomagnetic results exist for tectonic elements near the margin of west Gondwana that are unlikely to have been significantly displaced with respect to cratonic Africa and South America. These results have not previously been used for APWP reconstructions, because local rotations are thought to have deflected the paleopoles in many cases. The inclinations of such results, however, can be used to determine a locus of paleopole positions. Paleopole loci for about 150 and 170 Ma were determined from results from Spain, Italy, Lebanon, and the Chilean Andes, and these were rotated with appropriate parameters to give locus intersections in North American coordinates. A late Middle Jurassic (early Callovian) best estimate of the paleopole in North American coordinates is located at about lat 70°N, long 135°E, and a Late Jurassic (Kimmeridgian) best estimate is located at about 70°N, 155°E. The resulting Jurassic-Early Cretaceous APWP follows roughly the 70th parallel, passing through the middle of the scattered individual paleopoles from the cratonic parts of the Atlantic-bordering continents.

van der Voo, Rob

1992-11-01

433

Geochemistry of vanadium in an epigenetic, sandstone-hosted vanadium- uranium deposit, Henry Basin, Utah  

USGS Publications Warehouse

The epigenetic Tony M vanadium-uranium orebody in south-central Utah is hosted in fluvial sandstones of the Morrison Formation (Upper Jurassic). Measurements of the relative amounts of V+3 and V +4 in ore minerals show that V+3 is more abundant. Thermodynamic calculations show that vanadium was more likely transported to the site of mineralization as V+4. The ore formed as V+4 was reduced by hydrogen sulfide, followed by hydrolysis and precipitation of V+3 in oxide minerals or chlorite. Uranium was transported as uranyl ion (U+6), or some complex thereof, and reduced by hydrogen sulfide, forming coffinite. Detrital organic matter in the rocks served as the carbon source for sulfate-reducing bacteria. Vanadium most likely was derived from the dissolution of iron-titanium oxides. Uranium probably was derived from the overlying Brushy Basin Member of the Morrison Formation. Previous studies have shown that the ore formed at the density-stratified interface between a basinal brine and dilute meteoric water. The mineralization processes described above occurred within the mixing zone between these two fluids. -from Authors

Wanty, R.B.; Goldhaber, M.B.; Northrop, H.R.

1990-01-01

434

Examination of the relationship between Navajo generating station emissions and aerosol concentrations at Page, Arizona  

SciTech Connect

Identifying the chemical/physical characteristics and source of pollutants contributing to low lying wintertime layered hazes in the canyons along the Colorado River where it cuts through the Colorado River Plateau area is one objective of the subregional cooperative electric utility, national park service (NPS), Environmental Protection Agency (EPA) and Department of Defense (DOD) Study, (SCENES) consortium of industrial and government agencies. As part of SCENES, a short term special study, the winter haze intensive tracer experiment (WHITEX) was specially formulated to asses the feasibility of various receptor modeling techniques to attribute emissions from the Navajo Generating Station to aerosol concentrations in three National Park Service sites, Canyonlands and Grand Canyon National Parks and Glen Canyon National Recreation Area, to relate aerosol concentrations to atmospheric extinction and finally to relate extinction to visibility impairment.This paper focuses on a subset of WHITEX, the source of visibility reducing aerosols at Page (Lake Powell), Arizona.

Iyer, H.K. (Colorado State Univ., Fort Collins, CO (USA)); Malm, W.C. (National Park Service, Colorado State Univ., Fort Collins, CO (US))

1988-01-01

435

A "Role-play" Activity for Teaching about Uranium Mining on the Navajo Nation  

NSDL National Science Digital Library

This activity uses an assortment of digital resources relevant to exploring resource development on Native American lands. The activity is based on a website that uses an Earth System approach to help students understand how Native American lands have been impacted by resource development. In the role-playing exercise, students are assigned one of several roles, including consulting geologists, the mining industry, tribal elders and public health officials. Each student uses the web-based learning materials to research the issue from the perspective of their role. This type of exercise could also be used as a debate by dividing a class into groups that play the roles of the Navajo people and the Federal Government.

Erin Klauk

436

A new pterosaur tracksite from the jurassic summerville formation, near Ferron, Utah  

USGS Publications Warehouse

Pterosaur tracks (cf. Pteraichnus) from the Summerville Formation of the Ferron area of central Utah add to the growing record of Pteraichnus tracksites in the Late Jurassic Summerville Formation and time-equivalent, or near time-equivalent, deposits. The site is typical in revealing high pterosaur track densities, but low ichnodiversity suggesting congregations or "flocks" of many individuals. Footprint length varies from 2.0 to 7.0 cms. The ratio of well-preserved pes:manus tracks is about 1:3.4. This reflects a bias in favor of preservation of manus tracks due to the greater weight-bearing role of the front limbs, as noted in other pterosaur track assemblages. The sample also reveals a number of well-preserved trackways including one suggestive of pes-only progression that might be associated with take off or landing, and another that shows pronounced lengthening of stride indicating acceleration. One well-preserved medium-sized theropod trackway (Therangospodus) and other larger theropod track casts (cf. Megalosauripus) are associated with what otherwise appears to be a nearly monospecific pterosaur track assemblage. However, traces of a fifth pes digit suggest some tracks are of rhamphorynchoid rather than pterodactyloid origin, as usually inferred for Pteraichnus. The tracks occur at several horizons in a thin stratigraphic interval of ripple marked sandstones and siltstones. Overall the assemblage is similar to others found in the same time interval in the Western Interior from central and eastern Utah through central and southern Wyoming, Colorado, northeastern Arizona, and western Oklahoma. This vast "Pteraichnus ichnofacies" with associated saurischian tracks, remains the only ichnological evidence of pre-Cretaceous pterosaurs in North America and sheds important light on the vertebrate ecology of the Summerville Formation and contiguous deposits. ?? Taylor and Francis Inc.

Mickelson, D.L.; Lockley, M.G.; Bishop, J.; Kirkland, J.

2003-01-01

437

The Jurassic South Albanian ophiolites: MOR- vs. SSZ-type ophiolites  

NASA Astrophysics Data System (ADS)

Within the western belt of the southern Albanian ophiolites, the Voskopoja ophiolite consists of three subunits: Voskopoja, Morava and Rehove. These are predominantly lherzolites with minor harzburgites and dunites in the mantle section. Above come ultramafic and mafic cumulates including wehrlites, troctolites and olivine gabbros. Gabbronorites are restricted to the Morava subunit. Isotropic clinopyroxene gabbros, extrusives and sediments are present only in Rehove and Voskopoja. The volcanic section is dominated by basaltic breccias, including megablocks with sheeted dykes, pillow lavas and isolated dykes. The basaltic breccias grade upwards into sandstones, in turn, interlayered with argillites and cherts of Jurassic age. The basalts are predominantly clinopyroxene-plagioclase basalts, either aphyric or plagioclase phyric. Geochemically, they are divided into four groups: (1) an intermediate Ti and Zr group with low Ni (hereafter called low-Ni group), (2) an intermediate Ti-Zr group with high Ni (hereafter called high-Ni group), (3) a high-Ti-Zr group and (4) a low-Ti-Zr group. The high-Ni content in group 2 is interpreted as originating from olivine and spinel xenocrysts. Apart from the high-Ni content, groups 1 and 2 are comparable with the volcanics of the "low- to high-Ti intermediate ophiolites." By contrast, group 3 is more comparable to the high-Ti ophiolitic extrusives in the western ophiolite belt of northern Albania. Group 4 consists SSZ-type basalts and is widespread in the volcanics of the eastern ophiolite belt. Comparison of the ultramafic-mafic cumulates and the basaltic volcanics with those in the northern part of the western belt in Albania and the Pindos ophiolite indicates that there is a systematic variation in petrography and geochemistry from north to south in the western belt, with an increasingly distinct SSZ signature towards the south. Ultramafic and mafic cumulates, as well as basalts from the Shebenik massif in the eastern belt, are similar to those of Voskopoja, implying a genetic relationship.

Hoeck, V.; Koller, F.; Meisel, T.; Onuzi, K.; Kneringer, E.

2002-11-01

438

Pediatric motor vehicle related injuries in the Navajo Nation: the impact of the 1988 child occupant restraint laws  

PubMed Central

Background: Navajo motor vehicle mortality is the highest among the 12 Indian Health Service (IHS) administrative areas. In July 1988, the Navajo Nation enacted a primary enforcement safety belt use and a child restraint law. Objective: Assess the impact of the laws on the rate and severity of pediatric (0–19 years) motor vehicle injury resulting in hospitalizations in the Navajo Nation. Methods: Hospitalizations associated with motor vehicle related injury discharges were identified by International Classification of Diseases, 9th revision, CM E codes, 810–825 (.0,.1) from the Navajo IHS hospital discharge database. Age specific rates for the period before the law, 1983–88, were compared with those after enactment and enforcement, 1991–95. Severity of injury, measured by the abbreviated injury scale (AIS) score and new injury severity score (NISS), was determined with ICDMAP-90 software. Wilcoxon rank sum and ?2 tests were used for analysis. Results: Discharge rates (SE) for motor vehicle injury (per 100 000) decreased significantly in all age groups: 0–4 years (62 (7) to 28 (4)), 5–11 years (55.3 (6) to 26 (4)), and 15–19 years (139 (14) to 68 (7)); p=0.0001. In children 0–4 years, the median AIS score decreased from 1.5 (1,3) (25th, 75th centile) to 1 (1,2), p=0.06, and the median NISS decreased from 3.5 (1,9) to 2 (1,5), p=0.07. The proportion of children with NISS scores >4 decreased significantly for the 0–4 year age group (p=0.03). Conclusions: Concurrent with enactment of the Navajo Nation occupant and child restraint laws there was a reduction in the rate of motor vehicle related hospital discharges for children. Severity of injury declined in very young Navajo children. The effect of enactment and enforcement of this Native American child occupant restraint law may serve as an example of an effective injury control effort directed at Native American children. PMID:12226119

Phelan, K; Khoury, J; Grossman, D; Hu, D; Wallace, L; Bill, N; Kalkwarf, H

2002-01-01

439

Recognition of Jurassic transport of rocks of the Roberts Mountains allochthon: Evidence from the Sonoma Range, north-central Nevada  

NASA Astrophysics Data System (ADS)

The Sonoma Range of north-central Nevada exposes lower Paleozoic rocks of the Roberts Mountains allochthon that were thrust from east to west over Upper Triassic shelf strata in Jurassic time. Also present are Roberts Mountains allochthon rocks that were autochthonous in the Jurassic. Structural analysis of Jurassic allochthonous vs. Jurassic autochthonous rocks of the Harmony Formation indicates that both packages have the same east-verging Paleozoic deformation history: recumbent isoclines (F1), shallowly inclined tight folds (F2), then upright folds (F3). Three generations of Jurassic folds (F4, F5, F6) are present in the Jurassic allochthonous Harmony Formation, whereas the Jurassic autochthonous Harmony Formation has only the youngest Jurassic phase (F6). First Jurassic folds (F4) in the Jurassic allochthonous Harmony Formation are synemplacement major fault-bend folds. F4 folds F1-F3 and does not fold F5 and F6. F5 folds are markedly different from Paleozoic deformations and the younger Jurassic folds (F6) present in both the Jurassic allochthonous and Jurassic autochthonous Harmony Formation (major, upright, west-verging). Recognition of F5 folds in rocks of the Roberts Mountains allochthon north and east of the Sonoma Range may help define the geographic extent of Jurassic deformation in northern Nevada. These boundaries cannot be established by traditional means because of the absence of exposure of Upper Triassic to Middle Jurassic rocks in the region.

Stahl, Stephen D.

1989-07-01

440

New insights into regional tectonics of the Indochina Peninsula inferred from Lower-Middle Jurassic paleomagnetic data of the Sibumasu Terrane  

NASA Astrophysics Data System (ADS)

The post-Jurassic occurrence of differential tectonic rotation between the Indochina and South Sundaland blocks remains an issue to be properly investigated. New paleomagnetic study is used here to find the role of Sibumasu Terrane in this rotation, which is located between a clockwise rotated Indochina Block and a counter-clockwise rotated South Sundaland Block. For this purpose, lower to middle Jurassic red sandstones of the Umphang Group in the Sibumasu Terrane were sampled at 21 sites in the Ratchaburi area (13.6°E, 99.6°E), Thailand. Stepwise thermal demagnetization by 680 °C unblocked a pre-folding characteristic remanent magnetization. A mean direction of this component at 100% unfolding is Ds = 348.5°, Is = 24.7°, ?95 = 10.5°, k = 10.7, N = 20, corresponding to an Early-Middle Jurassic pole of ? = 78.6°N, ? = 10.6°E (A95 = 9.3). Comparison of this direction with those reported from other localities of the Umphang Group (Kalaw, Mae Sot and North Trang Syncline localities) reveal variable declinations (between 348.5° and 44.7°) for the Sibumasu Terrane. We ascribe this variation to differential tectonic deformation in the Sibumasu Terrane, as reflected from sinusoidal shaped structural features in the study area. The presence of such features in the granitic rocks indicates the occurrences of deformational activities after their intrusion, which took place in the period between 130 Ma and 51 Ma. The Sibumasu Terrane behaved as an independent fragment at a time when Indochina was undergoing a clockwise rotation and southward displacement, as a result of extrusion tectonics after the gigantic India-Asia collision. Taking into consideration a westerly deflected declination (D = 342.8°) from the West Trang area in Peninsular Thailand, a counterclockwise rotation of 15° is estimated for the Sibumasu Terrane, as a result of continuous northward indentation of the Australian Plate into South Sundaland Block.

Fujiwara, Katsuya P.; Zaman, Haider; Surinkum, Adichat; Chaiwong, Nikhom; Fujihara, Makoto; Ahn, Hyeon-Seon; Otofuji, Yo-ichiro

2014-11-01

441

Environmental significance of foraminiferal assemblages dominated by small-sized Ammodiscus and Trochammina in Triassic and Jurassic delta-influenced deposits  

NASA Astrophysics Data System (ADS)

The sediment packages analyzed for benthic foraminifera consist of mudstones with interbedded sandstones deposited in shallow delta-influenced shelf to deltaic environments. The sections are located in Spitsbergen, the Barents Sea, northern North Sea and Yorkshire, and range in age from Late Triassic to Middle Jurassic. Salient features of the foraminiferal successions are: (1) The assemblages consist entirely or dominantly of agglutinated taxa. (2) The faunal diversities are extremely low. (3) The dominant genera are Ammodiscus and Trochammina. (4) The species are generally of small size compared to usual dimensions within the genera. The features listed above suggest that the assemblages were adapted to restricted conditions (clearly divergent from those of a normal marine shelf), where the main limiting factors were low salinity and reduced amount of dissolved oxygen in unstable, storm-influenced environments. Evidence for environmental conditions is obtained from modern analogues, although the large evolutionary changes in foraminifera during post-Jurassic time make it difficult to find such analogues. Additional information is derived from functional morphology, sedimentary features and paleogeography. The analyzed sediment packages show close faunal similarities suggesting opening of a marine pathway, which connected the paleo-Arctic Ocean with the western European shelf seas in Early Jurassic. A depositional biofacies model of the small-sized Ammodiscus- Trochammina assemblages envisages a delta-influenced shelf environment, where high freshwater influx would have created a density-stratified water column with a tendency to develop hypoxic conditions in its deeper parts. The depth interval between fair-weather and storm wave base (the offshore-transition zone) is indicated as the habitat of the small-sized Ammodiscus- Trochammina assemblages. In this zone, benthic biota would have been stressed by intermittent periods with moderate hypoxia combined with lowered salinity and storm impacts.

Nagy, Jenö; Hess, Silvia; Alve, Elisabeth

2010-04-01

442

Power, Prayers, and Protection: Comb Ridge as a Case Study in Navajo Thought  

ERIC Educational Resources Information Center

Beginning in 2005, a five-year survey of cultural resources began to unfold in southeastern Utah along a prominent sandstone rock formation known as Comb Ridge. This visually dramatic monocline stretches a considerable distance from the southwestern corner of Blue Mountain (Abajos) in Utah to Kayenta, Arizona, approximately one hundred miles to…

McPherson, Robert S.

2010-01-01

443

Compaction of Norphlet sandstones, Rankin County, Mississippi  

SciTech Connect

Fabric and porosity changes resulting from compaction were studied in sandstones from three cores sampled at depths between 15,900 and 22,500 ft. Point counts of 30 thin sections indicate that 0.4% of the rock volume was lost by ductile grain deformation and 3% by pressure solution at both grain contacts and at widely spaced stylolites. Pre-cement porosities of eolian sandstone range from 27 to 35% (mean = 29%), indicating that a total of from 10 to 18% porosity (mean = 16%) was lost by compaction (assuming 45% initial porosity). The difference between the total porosity loss and the sum of the other two processes is assumed to be the porosity lost by grain rearrangement (mean = 12.6%). The amount of pressure solution at grain contacts for each well is independent of depth, temperature, and amount of both quartz cement and total cement. Stylolites transect both grains and cements, which indicates they formed late in the diagenetic sequence. Silica released by pressure solution at quartz grain contacts could not be the sole source and was probably not even the major source of quartz cement in the formation, because cementation by quartz preceded the episode of strong pressure solution. In addition, the volume of silica released by pressure solution appears to have been inadequate to provide the volume of quartz cement present.

McBride, E.F.

1987-09-01

444

Anisotropy of permeability in faulted porous sandstones  

NASA Astrophysics Data System (ADS)

Studies of fault rock permeabilities advance the understanding of fluid migration patterns around faults and contribute to predictions of fault stability. In this study a new model is proposed combining brittle deformation structures formed during faulting, with fluid flow through pores. It assesses the impact of faulting on the permeability anisotropy of porous sandstone, hypothesising that the formation of fault related micro-scale deformation structures will alter the host rock porosity organisation and create new permeability pathways. Core plugs and thin sections were sampled around a normal fault and oriented with respect to the fault plane. Anisotropy of permeability was determined in three orientations to the fault plane at ambient and confining pressures. Results show that permeabilities measured parallel to fault dip were up to 10 times higher than along fault strike permeability. Analysis of corresponding thin sections shows elongate pores oriented at a low angle to the maximum principal palaeo-stress (?1) and parallel to fault dip, indicating that permeability anisotropy is produced by grain scale deformation mechanisms associated with faulting. Using a soil mechanics 'void cell model' this study shows how elongate pores could be produced in faulted porous sandstone by compaction and reorganisation of grains through shearing and cataclasis.

Farrell, N. J. C.; Healy, D.; Taylor, C. W.

2014-06-01

445

Study on the texture of a low permeable sandstone reservoir  

Microsoft Academic Search

With the Maling oil field as an example, this study presents the origin of the pore texture of a low permeability sandstone reservoir and its influence on developmental results. Reservoirs in the Yan an Formation are channel sandstones which were intensively reformed by diagenesis. Their permeability is only 3 to 100 md, and porosity is 10 to 18%. Analysis by

Zhu

1982-01-01

446

Chemically induced strength changes in sandstone. Report of Investigations\\/1993  

Microsoft Academic Search

Chemical alteration of the compressive strength of sandstone has been investigated by the U.S. Bureau of Mines (USBM). Successful development of this technology would offer an attractive alternative to the methods now used for stress control in mines. Sandstone cores were stressed to failure under uniaxial compression at two different strain rates. Specimens saturated with either distilled or tap water

W. P. Stroud; D. R. Dolinar

1993-01-01

447

Diagenesis of the Almond sandstone in the Washakie Basin  

SciTech Connect

The marginal marine and nonmarine Almond sandstones are mostly sublitharenite, litharenite, and lithic arkose. The sandstones are fine-to very-fine-grained, and are well-sorted. The framework composition, authigenic minerals, and porosity and permeability distributions in the Almond sandstones are different below and above 8,000 feet, resulting in a variation in hydrocarbon reservoir types. The shallow conventional reservoirs are permeable, producing both liquid oil and gas, whereas the deep gas-bearing sandstones are very tight and overpressured. Porosity of the shallow Almond sandstones have been significantly enhanced by dissolution of the feldspar grains and lithic fragments. Quartz overgrowth cement and authigenic clay rims have occluded most of the intergranular pores, as well as the previously leached pores. The Almond sandstones have been buried deeper than their present depths. The sandstones in each part of the Washakie Basin have experienced different uplift and subsidence. Reconstruction of the burial history and diagenetic modeling are essential steps for understanding the diagenetic evolution of the Almond sandstones.

Yin, Peigui; Liu, Jie; Surdam, C.R. (Univ. of Wyoming, Laramie, WY (United States). Dept. of Geology and Geophysics)

1992-01-01

448

Mechanical behavior of Mesaverde shale and sandstone at high pressure  

Microsoft Academic Search

Rock mechanics measurements taken on Mesaverde shale (source rock) and sandstone (reservoir rock) from about 350 m depth (Colorado) and 1600 m depth (Wyoming) are reported. For each sandstone and shale, the following properties were determined: (1) tensile strength parallel and perpendicular to bedding, 0.1 MPa pressure; (2) triaxial stress failure envelope in compression to 300 MPa confining pressure, parallel

Wunan Lin

1981-01-01

449

Lessons Learned: Tribal Community Engagement, Remediation and Restoration of a Uranium Mine Tailings Site, Navajo Nation - 12484  

SciTech Connect

In May, 2011 New World Environmental Inc. was awarded a contract by the Navajo Nation Environmental Protection Agency to remediate an illegal radioactive waste disposal site located in the Navajo Nation. The initial scope included the excavation and shipment of an estimated 3,000 cubic yards of Uranium mine tailings and associated industrial waste. In this instance Stakeholders were supportive of the project, remediation and restoration, yet the movement of residual radioactive materials through tribal communities was a controversial issue. Other Stakeholder issues included site security, water sources for remediation activities, local residents' temporary re-location and care of livestock, right of way permissions and local workforce development. This presentation recaps the technical and non-technical issues encountered in the remediation and restoration the seven acre site and the outreach to surrounding communities. Cultural and equity issues resulting from historical problems associated with this and other sites in the immediate area and education and training. (authors)

Wadsworth, Donald K. [New World Environmental Inc., Livermore California 94550 (United States); Hicks, Allison H. [New World Environmental Inc., Irvine California 92614 (United States)

2012-07-01

450

New isotopic evidence for the origin of groundwater from the Nubian Sandstone Aquifer in the Negev, Israel  

USGS Publications Warehouse

The geochemistry and isotopic composition (H, O, S, Osulfate, C, Sr) of groundwater from the Nubian Sandstone (Kurnub Group) aquifer in the Negev, Israel, were investigated in an attempt to reconstruct the origin of the water and solutes, evaluate modes of water-rock interactions, and determine mean residence times of the water. The results indicate multiple recharge events into the Nubian sandstone aquifer characterized by distinctive isotope signatures and deuterium excess values. In the northeastern Negev, groundwater was identified with deuterium excess values of ???16???, which suggests local recharge via unconfined areas of the aquifer in the Negev anticline systems. The ??18OH2O and ??2H values (-6.5??? and -35.4???) of this groundwater are higher than those of groundwater in the Sinai Peninsula and southern Arava valley (-7.5??? and -48.3???) that likewise have lower deuterium excess values of ???10???. Based on the geochemical differences between groundwater in the unconfined and confined zones of the aquifer, a conceptual geochemical model for the evolution of the groundwater in the Nubian sandstone aquifer has been reconstructed. The isotopic composition of shallow groundwater from the unconfined zone indicates that during recharge oxidation of pyrite to SO4 (??34SSO4 ???-13???; ??18OSO4 ???+7.7???) and dissolution of CaCO3 (87Sr/86Sr ???0.70787; ??13CDIC = -3.7???) occur. In the confined zone of the aquifer, bacterial SO4 reduction removes a significant part of dissolved SO42 -, thereby modifying its isotopic composition (??34SSO4 ???-2???; ??18OSO4 ???+8.5???) and liberating dissolved inorganic C that contains little or no radiocarbon (14C-free) with low ??13CDIC values (<-12???). In addition to local recharge, the Sr and S isotopic data revealed contribution of external groundwater sources to the Nubian Sandstone aquifer, resulting in further modifications of the groundwater chemical and isotopic signatures. In the northeastern Negev, it is shown that SO4-rich groundwater from the underlying Jurassic aquifer contributes significantly to the salt budget of the Nubian Sandstone aquifer. The unique chemical and isotopic composition of the Jurassic groundwater (??34SSO4 ??? +14???; ??18OSO4 ??? 14???; 87Sr/86Sr ???0.70764) is interpreted as reflecting dissolution of Late Triassic marine gypsum deposits. In the southern Arava Valley the authors postulate that SO4-rich groundwater with distinctively high Br/Cl (3 ?? 10-3) low 87Sr/86Sr (0.70734), and high ??34SSO4 values (+15???) is derived from mixing with underlying brines from the Paleozoic units. The radiocarbon measurements reveal low 14C activities (0.2-5.8 pmc) in both the northeastern Negev and southern Arava Valley. Taking into account dissolution of carbonate rocks and bacterial SO4 reduction in the unconfined area, estimated mean residence times of groundwater in the confined zone in the northeastern Negev are on the order of 21-38 ka, which suggests recharge predominantly during the last glacial period. The 14C signal in groundwater from the southern Arava Valley is equally low but due to evidence for mixing with external water sources the residence time estimates are questionable. ?? 2007 Elsevier Ltd. All rights reserved.

Vengosh, A.; Hening, S.; Ganor, J.; Mayer, B.; Weyhenmeyer, C.E.; Bullen, T.D.; Paytan, A.

2007-01-01

451

Potential Triassic and Jurassic CO2 Storage Reservoirs in the Skagerrak Area  

NASA Astrophysics Data System (ADS)

Based on a screening study for CO2 storage in the Skagerrak area, we have focused on the Upper Triassic/Lowermost Jurassic Gassum Formation. A large shallow dipping reservoir structure has been identified in the northern Skagerrak area. The current study presents reservoir characteristics of the Gassum formation in the Fjerritslev trough and onto the Skagerrak Kattegat platform, and the corresponding reservoir model. This reservoir model is part of an ongoing interdisciplinary project with the overall goal to establish a basis for large-scale handling of CO2 in this area, including regional CO2 source and capture possibilities, transportation and infrastructure, possible storage sites as well as legal aspects relating to the whole CCS chain. The shallow dipping aquifer is regionally exteded and mapped in the Norwegian-Danish Basin, the Fjerritslev trough, and onto the Skagerrak Kattegat platform, and is found deeper than 800 m below sea level. In the south the formation is affected by salt tectonics (salt pillows, diapirs), while forming gently dipping layer structures towards the north. The Gassum reservoir consists of mainly shallow marine shoreface sandstones with associated estuarine deposits possibly deposited during sea-level low stands. Thickness of Gassum Formation from Danish wells is 70 - 220 m with sand to shale ratios between 60 - 70%. Based on the study, an injection well is proposed 50 km offshore Norway. The proposed injection depth is 2070 m with the reservoir pinch-out 38 km away towards north where the top reservoir is 117 m below the Quaternary sediments. The southern portion of the reservoir located in Denmark can be characterized from wells drilled for hydrocarbons and geothermal energy. In order to predict the reservoir facies/parameters and to make a realistic geologic model comprising the area closer to Norway, a regional geological model based on sequence stratigraphic interpretations is imperative. Using thicknesses from seismic data a pseudo-well was generated about 50 km north of an existing well in Denmark with the objective to predict facies. A depositional model with sediments sourced from north was assumed. A 50% thickness erosion of highstand sandstones was assumed at each cycle when sea level fell during a low stand. The removed thickness was compensated by non-reservoir transgressive systems tracts sediments (possible aggrading floodplain or lagoonal sediments). As good reservoir porosities (~20%) were found in wells in the south, porosities towards north are expected to be higher due to shallower depth of burial. The sealing properties of transgressive shales overlying the low stand sandstones are also important in local trapping and lateral distribution of the injected CO2. Furthermore the intercalation of shaly layers and permeability heterogeneities developed in prograding sand systems may provide additional trapping capacity to the reservoir. This geologic model is one of the likely scenarios that favors Gassum Formation as a potential CO2 storage reservoir in Skagerrak area and warrant to evaluate the reservoir using other possible scenarios.

Baig, I.; Aagaard, P.; Fawad, M.; Sassier, C.; Faleide, J. I.; Jahren, J.; Gabrielsen, R. H.; Nielsen, L. H.; Kristensen, L.; Bergmo, P. E. S.

2012-04-01

452

A new carnivorous dinosaur from the Late Jurassic Solnhofen archipelago.  

PubMed

Small Late Jurassic theropod dinosaurs are rare worldwide. In Europe these carnivorous dinosaurs are represented primarily by only two skeletons of Compsognathus, neither of which is well preserved. Here we describe a small new theropod dinosaur from the Late Jurassic period of Schamhaupten in southern Germany. Being exquisitely preserved and complete from the snout to the distal third of the tail, the new fossil is the best-preserved predatory, non-avian dinosaur in Europe. It possesses a suite of characters that support its identification as a basal coelurosaur. A cladistic analysis indicates that the new taxon is closer to maniraptorans than to tyrannosauroids, grouping it with taxa often considered to be compsognathids. Large portions of integument are preserved along its tail. The absence of feathers or feather-like structures in a fossil phylogenetically nested within feathered theropods indicates that the evolution of these integumentary structures might be more complex than previously thought. PMID:16541071

Göhlich, Ursula B; Chiappe, Luis M

2006-03-16

453

The Jurassic-Cretaceous volcanism in the Septentrional Patagonian Andes  

NASA Astrophysics Data System (ADS)

An extensive Jurassic-Cretaceous volcanism was recognized in the section of the Patagonian Cordillera situated between the 43° and 47°S parallels. Field observations and K-Ar geochronological determinations allowed to obtain a complete picture of the events that occured in the region. The volcanic activity started with andesitic pyroclastics with some dacitic intercalations in the Malm and continued until the Late Jurassic. Tithonian-Neocomian marine sediments in some areas point out a partial regional subsidence. In the Early Cretaceous, the volcanic activity was mainly andesitic, with some interbedded dacites in the upper part of the sequence, and intercalations of pyroclastic beds and clastic sediments. The calc-alkaline volcanics are associated to granitic and granodioritic plutons, and together characterize a volcanic arc on a continental margin.

Haller, Miguel J.; Lapido, Omar R.

1982-11-01

454

Sedimentology, diagenesis, and petrophysics of selected Cherokee group (Desmoinesian) sandstones in southeastern Kansas. Part 2  

SciTech Connect

Medium to very fine-grained sandstones of the Cherokee Group in S.E. Kansas were deposited by unidirectional currents in nearshore, continental channels resulting in sandstone deposits up to 35 m (116 ft) thick. Five lithofacies have been established: (1) conglomeratic sandstones subdivided into thin basal and thick sequence- capping conglomerates, (2) stacked sandstones, (3) crossbedded coarse sandstones, (4) rippled fine sandstones; and (5) interbedded sandstones, shales, and siltstones. The following diagenetic stages were established: Stage 1: rare, localized precipitation of concretionary calcite and siderite cements in both sandstones and shales; Stage 2: extensive chlorite coatings on grains and silica cementation; and Stage 3: patchy kaolinite, siderite, and dolomite-ankerite cements develop while feldspars, micas, and argillaceous rock fragments dissolve. A model is proposed for Cherokee Group sandstones which shows that coarser grain size, less cementation, and fewer argillaceous rock fragments are found in the coarse sandstone lithofacies in the lower portion of sandstone sequences. 96 references.

Woody, M.D.

1983-06-01

455

Petroleum potential of Lower-Jurassic deposits in Nurolsk megadepression  

NASA Astrophysics Data System (ADS)

Based on reservoir temperature measurement data from twenty-three reference well cross-sections and paleotemperature modeling, the thermal history of Lower-Jurassic Togur source rock within Nurolsk megadepression and its framing structures have been reconstr