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Sample records for south central alaska

  1. Frequency dependent Lg attenuation in south-central Alaska

    USGS Publications Warehouse

    McNamara, D.E.

    2000-01-01

    The characteristics of seismic energy attenuation are determined using high frequency Lg waves from 27 crustal earthquakes, in south-central Alaska. Lg time-domain amplitudes are measured in five pass-bands and inverted to determine a frequency-dependent quality factor, Q(f), model for south-central Alaska. The inversion in this study yields the frequency-dependent quality factor, in the form of a power law: Q(f) = Q0fη = 220(±30) f0.66(±0.09) (0.75≤f≤12Hz). The results from this study are remarkably consistent with frequency dependent quality factor estimates, using local S-wave coda, in south-central Alaska. The consistency between S-coda Q(f) and Lg Q(f) enables constraints to be placed on the mechanism of crustal attenuation in south-central Alaska. For the range of frequencies considered in this study both scattering and intrinsic attenuation mechanisms likely play an equal role.

  2. GIS coverages of the Castle Mountain Fault, south central Alaska

    USGS Publications Warehouse

    Labay, Keith A.; Haeussler, Peter J.

    2001-01-01

    The Castle Mountain fault is one of several major east-northeast-striking faults in southern Alaska, and it is the only fault with had historic seismicity and Holocene surface faulting. This report is a digital compilation of three maps along the Castle Mountain fault in south central Alaska. This compilation consists only of GIS coverages of the location of the fault, line attributes indicating the certainty of the fault location, and information about scarp height, where measured. The files are presented in ARC/INFO export file format and include metadata.

  3. Geologic framework and petroleum systems of Cook Inlet basin, south-central Alaska

    USGS Publications Warehouse

    LePain, D.L.; Stanley, R.G.; Helmold, K.P.; Shellenbaum, D.P.; Stone, D.M.; Hite, D.M.

    2013-01-01

    This report provides a comprehensive overview of the stratigraphy, structure, tectonics, and petroleum systems of the Cook Inlet basin, an important oil- and gas-producing region in south-central Alaska.

  4. Emsian (late Early Devonian) sponges from west-central and south-central Alaska

    USGS Publications Warehouse

    Rigby, J.K.; Blodgett, R.B.; Anderson, N.K.

    2009-01-01

    Relatively common specimens of the hypercalcified agelasiid sponge Hormospongia labyrinthica Rigby and Blodgett, 1983 and specimens of associated species of Hormospongia have been previously reported from Emsian and Eifelian stratigraphic units at several localities in south-central and southeastern Alaska (Rigby and Blodgett, 1983). Those sponges were first described from the type section of the Eifelian Cheeneetnuk Limestone in the McGrath A-5 quadrangle. Since then several additional specimens of Hormospongia labyrinthica have also been collected from a new locality in the Talkeetna C-6 quadrangle in southcentral Alaska (Figs. 1, 2.1), and are documented here.

  5. Seismicity and plate tectonics in south central Alaska

    NASA Technical Reports Server (NTRS)

    Van Wormer, J. D.; Davies, J.; Gedney, L.

    1974-01-01

    Hypocenter distribution shows that the Benioff zone associated with the Aleutian arc terminates in interior Alaska some 75 km north of the Denali fault. There appears to be a break in the subducting Pacific plate in the Yentna River-Prince William Sound area which separates two seismically independent blocks, similar to the segmented structure reported for the central Aleutian arc.

  6. Quaternary Uplift History of Wingham Island, South-Central Alaska

    USGS Publications Warehouse

    Chapman, James B.; Haeussler, Peter J.; Pavlis, Terry L.

    2009-01-01

    Marine terraces cut into Pleistocene deposits on Wingham Island in the Gulf of Alaska provide new constraints on the position of sea level, ice thickness and total glacioisostatic rebound at the end of the Last Glacial Maximum. A radiocarbon age of 13.9 +- 0.15 ka on the most prominent terrace is coincident with the end of meltwater pulse 1A, possibly suggestive of a link between changes in relative sea level and terrace formation. Isostatic modeling suggests a local ice thickness of 600 to 700 m with high (~10 cm/yr) initial rates of postglacial rebound. In addition to the unique ties to meltwater pulse 1A, the timing of emergence for Wingham Island following the Last Glacial Maximum has implications for the early migration of humans into North America.

  7. Geologic map of the Gulkana B-1 quadrangle, south-central Alaska

    SciTech Connect

    Richter, D.H.; Ratte, J.C.; Schmoll, H.R.; Leeman, W.P.; Smith, J.G.; Yehle, L.A.

    1989-01-01

    The quadrangle includes the Capital Mountain Volcano and the northern part of Mount Sanford Volcano in the Wrangell Mountains of south-central Alaska. The Capital Mountain volcano is a relatively small, andesitic shield volcano of Pleistocene age, which contains a 4-km-diameter summit caldera and a spectacular post-caldera radial dike swam. Lava flows from the younger Pleistocene Mount Sanford Volcano overlap the south side of the Capital Mountain Volcano. Copper-stained fractures in basaltic andesite related to a dike-filled rift of the North Sanford eruptive center are the only sign of mineralization in the quadrangle. Rock glaciers, deposits of Holocene and Pleistocene valley glaciers and Pleistocene Copper River basin glaciers mantle much of the volcanic bedrock below elevations of 5,500 ft.

  8. Climate variability and spruce beetle (Dendroctonus rufipennis) outbreaks in south-central and southwest Alaska.

    PubMed

    Sherriff, Rosemary L; Berg, Edward E; Miller, Amy E

    2011-07-01

    We used tree ring data (AD 1601-2007) to examine the occurrence of and climatic influences on spruce beetle (Dendroctonus rufipennis) outbreaks in south-central and southwest Alaska and found evidence of regional-scale outbreaks dating from the mid-1700s, related to climate variability at multiple temporal scales. Over interannual time scales (approximately 1-3 years), El Niño years, combined with severe late-summer drought, appeared to contribute significantly to spruce beetle outbreaks in the study area. Over multidecadal time scales (up to approximately 40 years), cool-phase Pacific Decadal Oscillation (PDO) conditions tended to precede beetle outbreaks, regardless of the phase of El Niño-Southern Oscillation (ENSO). All sites showed low-severity disturbances attributed to spruce beetle damage, most notably during the 1810s. During other major periods of disturbance (i.e., 1870s, 1910s, 1970s), the effects of spruce beetle outbreaks were of moderate or higher severity. The highly synchronized timing of spruce beetle outbreaks at interannual to multidecadal scales, and particularly the association between cool-phase PDO conditions and beetle disturbance, suggests that climate (i.e., temperature, precipitation) is a primary driver of outbreaks in the study area. Our disturbance chronologies (mid-1700s to present) suggest that recent irruptions (1990s to present) in south-central and southwest Alaska are within the historical geographic range, but that outbreaks since the 1990s show greater spatiotemporal synchrony (i.e., more sites record high-severity infestations) than at any other time in the past approximatly 250 years.

  9. A Century of Retreat at Portage Glacier, South-Central Alaska

    USGS Publications Warehouse

    Kennedy, Ben W.; Trabant, Dennis C.; Mayo, Lawrence R.

    2006-01-01

    Introduction: The Portage Glacier, in south-central Alaska, is viewed by thousands of visitors annually who come to the U.S. Forest Service Begich, Boggs Visitor Center located on the road system between Anchorage and Whittier, Alaska. During the past century, the terminus of the glacier has retreated nearly 5 kilometers to its present location (fig. 1). Like other glaciers that terminate in water, such as Columbia Glacier near Valdez or Mendenhall Glacier near Juneau, Portage Glacier has experienced accelerated retreats in recent decades that likely were initially triggered by climate change begun at the end of the Little Ice Age in the mid-1800s and subsequently controlled in recent history primarily by calving of the glacier terminus. Photographic records of the terminus covering 1914 until present day track the patterns of retreat. These data, coupled with USGS climate information collected from the southern end of the ice field, provide insight to the patterns of retreat that might be observed in the future.

  10. Stratigraphic and compositional complexities of the late Quaternary Lethe tephra in South-central Alaska

    USGS Publications Warehouse

    Riehle, J.R.; Ager, T.A.; Reger, R.D.; Pinney, D.S.; Kaufman, D.S.

    2008-01-01

    Recently discovered Lethe tephra has been proposed as a latest Pleistocene marker bed in Bristol Bay lowland NE to the Cook Inlet region, Alaska, on the basis of correlations involving a single "Lethe average" glass composition. Type deposits in the Valley of Ten Thousand Smokes, however, are chemically heterogeneous-individual lapilli as well as aggregate ash deposits have glass compositions that range from the average mode to much higher SiO2 and K2O. Moreover, a lake-sediment core from the Cook Inlet region contains one ash deposit similar to "Lethe average" and other, closely underlying deposits that resemble a mixture of the average mode and high-Si high-K mode of proximal deposits. Synthesis of previously published radiocarbon ages indicates a major eruption mainly of "Lethe average" mode about 13,000 14C yr BP. As many as six deposits in the Cook Inlet region-five chiefly "Lethe average" mode-range from about 13,000 to 15-16,000 14C yr BP, and an early Holocene deposit in the Bristol Bay lowland extends the minimum age range of Lethe tephra throughout this region to 8000 14C yr BP. Because of the appearance of "Lethe average" composition in multiple deposits spanning thousands of years, we urge caution when using a Lethe-like composition as a basis for inferring a latest Pleistocene age of a tephra deposit in south-central Alaska. Linear variation plots suggest that magma mixing caused the Lethe heterogeneity; multiple magmas were involved as well in other large pyroclastic eruptions such as Katmai (Alaska) and Rotorua (New Zealand). Lethe is an example of a heterogeneous tephra that may be better compared with other tephras by use of plots of individual analytical points rather than by calculating similarity coefficients based on edited data. ?? 2006 Elsevier Ltd and INQUA.

  11. Mid-Holocene Sector Collapse at Mount Spurr Volcano, South-Central Alaska

    USGS Publications Warehouse

    Waythomas, Christopher F.

    2007-01-01

    Radiocarbon-dated volcanic mass-flow deposits on the southeast flank of Mount Spurr in south-central Alaska provide strong evidence for the timing of large-scale destruction of the south flank of the volcano by sector collapse at 4,769^ndash;4,610 yr B.P. The sector collapse created an avalanche caldera and produced an ~1-km3-volume clay-rich debris avalanche that flowed into the glacially scoured Chakachatna River valley, where it transformed into a lahar that extended an unknown distance beyond the debris avalanche. Hydrothermal alteration, an unbuttressed south flank of the volcano, and local structure have been identified as plausible factors contributing to the instability of the edifice. The sector collapse at Mount Spurr is one of the later known large-volume (>1 km,sup>3) flank failures recognized in the Aleutian Arc and one of the few known Alaskan examples of transformation of a debris avalanche into a lahar.

  12. Presence of rapidly degrading permafrost plateaus in south-central Alaska

    NASA Astrophysics Data System (ADS)

    Jones, Benjamin M.; Baughman, Carson A.; Romanovsky, Vladimir E.; Parsekian, Andrew D.; Babcock, Esther L.; Stephani, Eva; Jones, Miriam C.; Grosse, Guido; Berg, Edward E.

    2016-11-01

    Permafrost presence is determined by a complex interaction of climatic, topographic, and ecological conditions operating over long time scales. In particular, vegetation and organic layer characteristics may act to protect permafrost in regions with a mean annual air temperature (MAAT) above 0 °C. In this study, we document the presence of residual permafrost plateaus in the western Kenai Peninsula lowlands of south-central Alaska, a region with a MAAT of 1.5 ± 1 °C (1981-2010). Continuous ground temperature measurements between 16 September 2012 and 15 September 2015, using calibrated thermistor strings, documented the presence of warm permafrost (-0.04 to -0.08 °C). Field measurements (probing) on several plateau features during the fall of 2015 showed that the depth to the permafrost table averaged 1.48 m but at some locations was as shallow as 0.53 m. Late winter surveys (augering, coring, and GPR) in 2016 showed that the average seasonally frozen ground thickness was 0.45 m, overlying a talik above the permafrost table. Measured permafrost thickness ranged from 0.33 to > 6.90 m. Manual interpretation of historic aerial photography acquired in 1950 indicates that residual permafrost plateaus covered 920 ha as mapped across portions of four wetland complexes encompassing 4810 ha. However, between 1950 and ca. 2010, permafrost plateau extent decreased by 60.0 %, with lateral feature degradation accounting for 85.0 % of the reduction in area. Permafrost loss on the Kenai Peninsula is likely associated with a warming climate, wildfires that remove the protective forest and organic layer cover, groundwater flow at depth, and lateral heat transfer from wetland surface waters in the summer. Better understanding the resilience and vulnerability of ecosystem-protected permafrost is critical for mapping and predicting future permafrost extent and degradation across all permafrost regions that are currently warming. Further work should focus on reconstructing

  13. Shrubline but not treeline advance matches climate velocity in montane ecosystems of south-central Alaska.

    PubMed

    Dial, Roman J; Smeltz, T Scott; Sullivan, Patrick F; Rinas, Christina L; Timm, Katriina; Geck, Jason E; Tobin, S Carl; Golden, Trevor S; Berg, Edward C

    2016-05-01

    Tall shrubs and trees are advancing into many tundra and wetland ecosystems but at a rate that often falls short of that predicted due to climate change. For forest, tall shrub, and tundra ecosystems in two pristine mountain ranges of Alaska, we apply a Bayesian, error-propagated calculation of expected elevational rise (climate velocity), observed rise (biotic velocity), and their difference (biotic inertia). We show a sensitive dependence of climate velocity on lapse rate and derive biotic velocity as a rigid elevational shift. Ecosystem presence identified from recent and historic orthophotos ~50 years apart was regressed on elevation. Biotic velocity was estimated as the difference between critical point elevations of recent and historic logistic fits divided by time between imagery. For both mountain ranges, the 95% highest posterior density of climate velocity enclosed the posterior distributions of all biotic velocities. In the Kenai Mountains, mean tall shrub and climate velocities were both 2.8 m y(-1). In the better sampled Chugach Mountains, mean tundra retreat was 1.2 m y(-1) and climate velocity 1.3 m y(-1). In each mountain range, the posterior mode of tall woody vegetation velocity (the complement of tundra) matched climate velocity better than either forest or tall shrub alone, suggesting competitive compensation can be important. Forest velocity was consistently low at 0.1-1.1 m y(-1), indicating treeline is advancing slowly. We hypothesize that the high biotic inertia of forest ecosystems in south-central Alaska may be due to competition with tall shrubs and/or more complex climate controls on the elevational limits of trees than tall shrubs. Among tall shrubs, those that disperse farthest had lowest inertia. Finally, the rapid upward advance of woody vegetation may be contributing to regional declines in Dall's sheep (Ovis dalli), a poorly dispersing alpine specialist herbivore with substantial biotic inertia due to dispersal reluctance.

  14. Assessment of unconvential (tight) gas resources in Upper Cook Inlet Basin, South-central Alaska

    USGS Publications Warehouse

    Schenk, Christopher J.; Nelson, Philip H.; Klett, Timothy R.; Le, Phuong A.; Anderson, Christopher P.; Schenk, Christopher J.

    2015-01-01

    A geologic model was developed for the assessment of potential Mesozoic tight-gas resources in the deep, central part of upper Cook Inlet Basin, south-central Alaska. The basic premise of the geologic model is that organic-bearing marine shales of the Middle Jurassic Tuxedni Group achieved adequate thermal maturity for oil and gas generation in the central part of the basin largely due to several kilometers of Paleogene and Neogene burial. In this model, hydrocarbons generated in Tuxedni source rocks resulted in overpressure, causing fracturing and local migration of oil and possibly gas into low-permeability sandstone and siltstone reservoirs in the Jurassic Tuxedni Group and Chinitna and Naknek Formations. Oil that was generated either remained in the source rock and subsequently was cracked to gas which then migrated into low-permeability reservoirs, or oil initially migrated into adjacent low-permeability reservoirs, where it subsequently cracked to gas as adequate thermal maturation was reached in the central part of the basin. Geologic uncertainty exists on the (1) presence of adequate marine source rocks, (2) degree and timing of thermal maturation, generation, and expulsion, (3) migration of hydrocarbons into low-permeability reservoirs, and (4) preservation of this petroleum system. Given these uncertainties and using known U.S. tight gas reservoirs as geologic and production analogs, a mean volume of 0.64 trillion cubic feet of gas was assessed in the basin-center tight-gas system that is postulated to exist in Mesozoic rocks of the upper Cook Inlet Basin. This assessment of Mesozoic basin-center tight gas does not include potential gas accumulations in Cenozoic low-permeability reservoirs.

  15. Assessment of undiscovered oil and gas resources of the Cook Inlet region, south-central Alaska, 2011

    USGS Publications Warehouse

    Stanley, Richard G.; Charpentier, Ronald R.; Cook, Troy A.; Houseknecht, David W.; Klett, Timothy R.; Lewis, Kristen A.; Lillis, Paul G.; Nelson, Philip H.; Phillips, Jeffrey D.; Pollastro, Richard M.; Potter, Christopher J.; Rouse, William A.; Saltus, Richard W.; Schenk, Christopher J.; Shah, Anjana K.; Valin, Zenon C.

    2011-01-01

    The U.S. Geological Survey (USGS) recently completed a new assessment of undiscovered, technically recoverable oil and gas resources in the Cook Inlet region of south-central Alaska. Using a geology-based assessment methodology, the USGS estimates that mean undiscovered volumes of nearly 600 million barrels of oil, about 19 trillion cubic feet of natural gas, and 46 million barrels of natural gas liquids remain to be found in this area.

  16. Coalbed methane, Cook Inlet, south-central Alaska: A potential giant gas resource

    USGS Publications Warehouse

    Montgomery, S.L.; Barker, C.E.

    2003-01-01

    Cook Inlet Basin of south-central Alaska is a forearc basin containing voluminous Tertiary coal deposits with sufficient methane content to suggest a major coalbed gas resource. Coals ranging in thickness from 2 to 50 ft (0.6 to 15 m) and in gas content from 50 to 250 scf/ton (1.6 to 7.8 cm2/g) occur in Miocene-Oligocene fluvial deposits of the Kenai Group. These coals have been identified as the probable source of more than 8 tcf gas that has been produced from conventional sandstone reservoirs in the basin. Cook Inlet coals can be divided into two main groups: (1) those of bituminous rank in the Tyonek Formation that contain mainly thermogenic methane and are confined to the northeastern part of the basin (Matanuska Valley) and to deep levels elsewhere; and (2) subbituminous coals at shallow depths (<5000 ft [1524 m]) in the Tyonek and overlying Beluga formations, which contain mainly biogenic methane and cover most of the central and southern basin. Based on core and corrected cuttings-desorption analyses, gas contents average 230 scf/ton (7.2 cm2/g) for bituminous coals and 80 scf/ton (2.5 cm2/g) for subbituminous coals. Isotherms constructed for samples of both coal ranks suggest that bituminous coals are saturated with respect to methane, whereas subbituminous coals at shallow depths along the eroded west-central basin margin are locally unsaturated. A preliminary estimate of 140 tcf gas in place is derived for the basin.

  17. Breeding ecology of Wandering Tattlers Tringa incana: a study from south-central Alaska

    USGS Publications Warehouse

    Gill, Robert; Tomkovich, Pavel S.; Dementyev, Maksim N.

    2015-01-01

    Montane-nesting shorebirds are arguably the least studied of the Charadriiformes, owing in part to the remoteness of their breeding areas, low nesting densities, and specialized behaviors. We studied a marked population of the Wandering Tattler Tringa incana, during a three-year period (1997–1999) on nesting grounds in south-central Alaska. Two aspects of our results stand out. First is the previously undescribed preference for tattlers to nest several kilometers removed from pre-nesting feeding areas, mostly in association with both small (kettle) lakes and running water (near small distributaries of major drainages). Second is the apparent use of the study area by cohorts of birds of different breeding status, including (1) local breeders, which defended pre-breeding foraging areas, (2) local non-breeding birds, which remained on the area but were not territorial, and (3) transients that were captured later in the season, but not seen again on the area during the season of capture. We also found that (1) birds tended to nest in clusters despite what appeared to be the ample availability of nesting habitat, (2) they employed an inconspicuous’ nesting strategy whereby neither member of a pair betrayed its presence on the nesting area, and (3) females departed the area during early chick-rearing, leaving males to tend broods.

  18. Estuarine environments as rearing habitats for juvenile Coho Salmon in contrasting south-central Alaska watersheds

    USGS Publications Warehouse

    Hoem Neher, Tammy D.; Rosenberger, Amanda E.; Zimmerman, Christian E.; Walker, Coowe M.; Baird, Steven J.

    2013-01-01

    For Pacific salmon, estuaries are typically considered transitional staging areas between freshwater and marine environments, but their potential as rearing habitat has only recently been recognized. The objectives of this study were two-fold: (1) to determine if Coho Salmon Oncorhynchus kisutch were rearing in estuarine habitats, and (2) to characterize and compare the body length, age, condition, and duration and timing of estuarine occupancy of juvenile Coho Salmon between the two contrasting estuaries. We examined use of estuary habitats with analysis of microchemistry and microstructure of sagittal otoliths in two watersheds of south-central Alaska. Juvenile Coho Salmon were classified as estuary residents or nonresidents (recent estuary immigrants) based on otolith Sr : Ca ratios and counts of daily growth increments on otoliths. The estuaries differed in water source (glacial versus snowmelt hydrographs) and in relative estuarine and watershed area. Juvenile Coho Salmon with evidence of estuary rearing were greater in body length and condition than individuals lacking evidence of estuarine rearing. Coho Salmon captured in the glacial estuary had greater variability in body length and condition, and younger age-classes predominated the catch compared with the nearby snowmelt-fed, smaller estuary. Estuary-rearing fish in the glacial estuary arrived later and remained longer (39 versus 24 d of summer growth) during the summer than did fish using the snowmelt estuary. Finally, we observed definitive patterns of overwintering in estuarine and near shore environments in both estuaries. Evidence of estuary rearing and overwintering with differences in fish traits among contrasting estuary types refute the notion that estuaries function as only staging or transitional habitats in the early life history of Coho Salmon.

  19. Late Holocene climate change at Goat Lake, Kenai Mountains, south-central Alaska

    NASA Astrophysics Data System (ADS)

    Daigle, T. A.; Kaufman, D. S.

    2006-12-01

    Lake sediments, glacier extents, and tree rings were used to reconstruct late Holocene climate changes from Goat Lake in the Kenai Mountains, south-central Alaska (60° 14' N/149° 54' W). Two sediment cores (3.7 and 5.6 m long) were dated with 16 AMS 14C ages and record changes in watershed (organic- matter content) and within-lake (biogenic silica) productivity since ~9500 cal yr BP. Sediment analyses focused on the last 1000 yr; this interval includes a sharp transition from gyttja to inorganic mud at ~1660 AD, which marks the fist time since Pleistocene deglaciation that the north goat outlet glacier (NGO) of the Harding Icefield overtopped the drainage divide at 590 m asl to spill meltwater into Goat Lake. One 14C age of ~1535 AD from a subfossil log in the NGO valley requires ~125 yr for the NGO to thicken 150 m to the elevation of the drainage divide where it remained until ~1930. Since ~1930, the NGO has thinned 150 m and retreated 1.4 km. Equilibrium-line altitudes (ELA) were reconstructed for 12 cirque glaciers nearby Goat Lake based on the accumulation-area ratio (AAR) method following field mapping of ice-marginal features formed during the maximum Little Ice Age (LIA) in the 19th century. Maximum LIA ELA data (AAR = 0.58) were compared with 1950 ELA and yield an average lowering of 50 ± 20 m. Application of the local lapse rate of 0.47°C/100 m indicates an average ablation-season temperature reduction of 0.3°C during the maximum LIA compared to 1950, assuming no change in winter precipitation. A new tree-ring chronology from 27 hemlock trees in the Goat Lake watershed correlates with mean March through August temperature from Kenai airport (r = 0.35) and a 207 yr reconstruction indicates an average temperature reduction of 1.0°C from 1800-1900 compared with 1930-1950. Assuming no change in winter precipitation, then a 1°C cooling should have been associated with an ELA lowering by 200 m. This did not occur, and we suggest that some degree of

  20. LANDSAT demonstration/application and GIS integration in south central Alaska

    NASA Technical Reports Server (NTRS)

    Burns, A. W.; Derrenbacher, W.

    1981-01-01

    Automated geographic information systems were developed for two sites in Southcentral Alaska to serve as tests for both the process of integrating classified LANDSAT data into a comprehensive environmental data base and the process of using automated information in land capability/suitability analysis and environmental planning. The Big Lake test site, located approximately 20 miles north of the City of Anchorage, comprises an area of approximately 150 square miles. The Anchorage Hillside test site, lying approximately 5 miles southeast of the central part of the city, extends over an area of some 25 square miles. Map construction and content is described.

  1. Late Holocene glacial history of the Copper River Delta, coastal south-central Alaska, and controls on valley glacier fluctuations

    NASA Astrophysics Data System (ADS)

    Barclay, David J.; Yager, Elowyn M.; Graves, Jason; Kloczko, Michael; Calkin, Parker E.

    2013-12-01

    Fluctuations of four valley glaciers in coastal south-central Alaska are reconstructed for the past two millennia. Tree-ring crossdates on 216 glacially killed stumps and logs provide the primary age control, and are integrated with glacial stratigraphy, ages of living trees on extant landforms, and historic forefield photographs to constrain former ice margin positions. Sheridan Glacier shows four distinct phases of advance: in the 530s to c.640s in the First Millennium A.D., and the 1240s to 1280s, 1510s to 1700s, and c.1810s to 1860s during the Little Ice Age (LIA). The latter two LIA advances are also recorded on the forefields of nearby Scott, Sherman and Saddlebag glaciers. Comparison of the Sheridan record with other two-millennia long tree-ring constrained valley glacier histories from south-central Alaska and Switzerland shows the same four intervals of advance. These expansions were coeval with decreases in insolation, supporting solar irradiance as the primary pacemaker for centennial-scale fluctuations of mid-latitude valley glaciers prior to the 20th century. Volcanic aerosols, coupled atmospheric-oceanic systems, and local glacier-specific effects may be important to glacier fluctuations as supplemental forcing factors, for causing decadal-scale differences between regions, and as a climatic filter affecting the magnitude of advances.

  2. Use of Potential Fields Data to Identify Petrological Controls on Seismicity within South-Central and Southeastern Alaska

    NASA Astrophysics Data System (ADS)

    Doser, D. I.; Veilleux, A. M.; Rodriguez, H.; de La Pena, A.; Mankhemthong, N.

    2010-12-01

    We have used data from regional gravity and aeromagnetic surveys to determine how variations in petrological properties of the upper plate(s) and subducting lower plate(s) influence the concentration of background seismicity in south-central and southeastern Alaska, as well as possible controls on asperities that ruptured during great earthquakes along the plate margin. In the Prince William Sound region it appears that seismicity concentrates at the edges of mafic and ultramafic bodies within the upper (North American) plate, while within Cook Inlet upper plate seismicity concentrates at the edges of a large serpentinite body. Rupture segmentation during the 1958 Fairweather earthquake in southeastern Alaska is associated with gravity highs along the Fairweather fault, while segmentation of the Queen Charlotte fault system appears related to changes in the structure of the Pacific plate. Although gravity coverage within the St. Elias region is sparse, background seismicity at depths of 10 to 20 km, including aftershocks of the 1979 Mw=7.4 St. Elias event, wraps around the edge of a gravity high located at the intersection of the Pamplona and Chugach-St. Elias fault systems. These results emphasize how additional gravity and magnetic data collection should be included as part of the upcoming Earthscope initiative in Alaska.

  3. A Detailed Geochemical Study of Island Arc Crust: The Talkeetna Arc Section, South-central Alaska

    NASA Astrophysics Data System (ADS)

    Greene, A. R.; Debari, S. M.; Kelemen, P. B.; Clift, P. D.; Blusztajn, J.

    2002-12-01

    The Talkeetna arc section in south-central Alaska is recognized as the exposed upper mantle and crust of an accreted, Late Triassic to Middle Jurassic island arc. Detailed geochemical studies of layered gabbronorite from the middle and lower crust of this arc and a diverse suite of volcanic and plutonic rocks from the middle and upper crust provide crucial data for understanding arc magma evolution. We also present new data on parental magma compositions for the arc. The deepest level of the arc section consists of residual mantle and ultramafic cumulates adjacent to garnet gabbro and basal gabbronorite interlayered with pyroxenite. The middle crust is primarily layered gabbronorite, ranging from anorthosite to pyroxenite in composition, and is the most widespread plutonic lithology. The upper mid crust is a heterogenous assemblage of dioritic to tonalitic rocks mixed with gabbro and intruded by abundant mafic dikes and chilled pillows. The upper crust of the arc is comprised of volcanic rocks of the Talkeetna Formation ranging from basalt to rhyolite. Most of these volcanic rocks have evolved compositions (<5% MgO, Mg# <60) and overlap the composition of intermediate to felsic plutonic rocks (<3.5% MgO, Mg# <45). However, several chilled mafic rocks and one basalt have primitive characteristics (>8% MgO, Mg# >60). Ion microprobe analyses of clinopyroxene in mid-crustal layered gabbronorites have parallel REE patterns with positive-sloping LREE segments (La/Sm(N)=0.05-0.17; mean 0.11) and flat HREE segments (5-25xchondrite; mean 10xchondrite). Liquids in REE equilibrium with the clinopyroxene in these gabbronorite cumulates were calculated in order to constrain parental magmas. These calculated liquids(La/Sm(N)=0.77-1.83; mean 1.26) all fall within the range of dike and volcanic rock(La/Sm(N)=0.78-2.12; mean 1.23) compositions. However, three lavas out of the 44 we have analyzed show strong HREE depletion, which is not observed in any of the liquid compositions

  4. Limnology of Big Lake, south-central Alaska, 1983-84

    USGS Publications Warehouse

    Woods, Paul F.

    1992-01-01

    The limnological characteristics and trophic state of Big Lake in south-central Alaska were determined from the results of an intensive study during 1983-84. The study was begun in response to concern over the potential for eutrophication of Big Lake, which has experienced substantial residential development and recreational use because of its proximity to Anchorage. The east and west basins of the 1,213 square-hectometer lake were each visited 36 times during the 2-year study to obtain a wide variety of physical, chemical, and biological data. During 1984, an estimate was made of the lake's annual primary production. Big Lake was classified as oligotrophic on the basis of its annual mean values for total phosphorus (9.5 micrograms per liter), total nitrogen (209 micrograms per liter), chlorophyll-a (2.5 micrograms per liter), secchi-disc transparency (6.3 meters), and its mean daily integral primary production of 81.1 milligrams of carbon fixed per square meter. The lake was, however, uncharacteristic of oligotrophic lakes in that a severe dissolved-oxygen deficit developed within the hypolimnion during summer stratification and under winter ice cover. The summer dissolved-oxygen deficit resulted from the combination of strong and persistent thermal stratification, which developed within 1 week of the melting of the lake's ice cover in May, and the failure of the spring circulation to fully reaerate the hypolimnion. The autumn circulation did reaerate the entire water column, but the ensuing 6 months of ice and snow cover prevented atmospheric reaeration of the water column and led to development of the winter dissolved-oxygen deficit. The anoxic conditions that eventually developed near the lake bottom allowed the release of nutrients from the bottom sediments and facilitated ammonification reactions. These processes yielded hypolimnetic concentrations of nitrogen and phosphorus compounds, which were much larger than the oligotrophic concentrations measured

  5. Tectonic implications of paleomagnetic poles from Lower Tertiary Volcanic Rocks, south central Alaska

    NASA Astrophysics Data System (ADS)

    Hillhouse, John W.; Grommé, C. Sherman; Csejtey, Bela, Jr.

    1985-12-01

    We have determined the paleolatitude of lower Tertiary volcanic rocks in southern Alaska to measure possible poleward translation of the Wrangellia and the Peninsular terranes after 50 m.y. ago. Previous paleomagnetic studies have shown that in Triassic and Jurassic time these terranes were located near the equator and have moved at least 3000 km poleward relative to the North American craton. Our sample localities are in the northern Talkeetna Mountains in mildly deformed andesite and dacite flows (50.4, 51.3, 53.9, and 56.3 m.y. by K-Ar) that overlap Lower Cretaceous flysch, Lower Permian volcanic rocks of Wrangellia, and Upper Triassic pillow basalt of the Susitna terrane. Results from 26 cooling units (23 of reversed polarity and 3 of normal polarity) give a mean paleomagnetic pole at 69.5°N, 179.6°E, α95 = 12.2°. Stratigraphic sections from opposite limbs of a syncline yield directional paths that pass the fold test, satisfying a necessary condition for primary origin of the magnetization. The corresponding mean paleolatitude (76°N) of the northern Talkeetna Mountains is 8°±10° higher than the latitude predicted from the Eocene reference pole for North America. Therefore, northward drift of the Talkeetna superterrane, which is the amalgamation of the Wrangellia and Peninsular terranes during and after Middle Jurassic time, was probably complete by 50 m.y. ago. Our results are consistent with paleomagnetic poles from uppermost Cretaceous and Paleocene volcanic sequences in Denali National Park, the Lake Clark region, northern Bristol Bay region, and near McGrath. These poles generally lie south of the cratonic poles, suggesting that the region between the Kaltag, Bruin Bay, and Castle Mountain faults has rotated counterclockwise relative to North America since the early Eocene.

  6. Migration And wintering areas Of Glaucous-winged Gulls From south-central Alaska

    USGS Publications Warehouse

    Hatch, Scott A.; Gill, V.A.; Mulcahy, Daniel M.

    2011-01-01

    We used satellite telemetry to investigate the migration patterns and wintering areas of Glaucous-winged Gulls (Larus glaucescens) from Middleton Island, Alaska, where this species' population increased tenfold from the 1970s to the 1990s. Fall migration spanned 11 weeks, including numerous stopovers en route, apparently for feeding. Spring migration from wintering sites to Middleton Island was shorter (4 weeks) and more direct. One juvenile spent several months in southern Prince William Sound. An adult spent several months near Craig, southeast Alaska, while three others overwintered in southern British Columbia. For all four wintering adults use of refuse-disposal sites was evident or strongly suggested. Commensalism with humans may have contributed to the increase on Middleton, but a strong case can also be made for a competing explanation-regional recruitment of gulls to high-quality nesting habitat in Alaska created after the earthquake of 1964. An analysis of band returns reveals broad overlap in the wintering grounds of gulls from different Alaska colonies and of gulls banded on the west coast from British Columbia to California. The seasonal movement of many gulls from Alaska is decidedly migratory, whereas gulls from British Columbia, Washington, and Oregon disperse locally in winter.

  7. Migration and wintering areas of glaucous-winged Gulls from south-central Alaska

    USGS Publications Warehouse

    Hatch, Shyla A.; Gill, V.A.; Mulcahy, D.M.

    2011-01-01

    We used satellite telemetry to investigate the migration patterns and wintering areas of Glaucouswinged Gulls (Larus glaucescens) from Middleton Island, Alaska, where this species' population increased tenfold from the 1970s to the 1990s. Fall migration spanned 11 weeks, including numerous stopovers en route, apparently for feeding. Spring migration from wintering sites to Middleton Island was shorter (4 weeks) and more direct. One juvenile spent several months in southern Prince William Sound. An adult spent several months near Craig, southeast Alaska, while three others overwintered in southern British Columbia. For all four wintering adults use of refuse-disposal sites was evident or strongly suggested. Commensalism with humans may have contributed to the increase on Middleton, but a strong case can also be made for a competing explanation-regional recruitment of gulls to high-quality nesting habitat in Alaska created after the earthquake of 1964. An analysis of band returns reveals broad overlap in the wintering grounds of gulls from different Alaska colonies and of gulls banded on the west coast from British Columbia to California. The seasonal movement of many gulls from Alaska is decidedly migratory, whereas gulls from British Columbia, Washington, and Oregon disperse locally in winter. ?? The Cooper Ornithological Society 2011.

  8. Role of lake regulation on glacier fed rivers in enhancing salmon productivity: The Cook Inlet watershed south central Alaska, USA

    USGS Publications Warehouse

    Hupp, C.R.

    2000-01-01

    Rivers fed by glaciers constitute a major part of the freshwater runoff into the Cook Inlet basin of south-central Alaska. This basin is very important to the economy of the State of Alaska because it is home to more than half of the population and it supports multi-million dollar commercial, subsistence and sport fisheries. Hence an understanding of how glacial runoff influences biological productivity is important for managing rivers that drain into Cook Inlet. This paper examines the ways in which the regulation of glacier-fed rivers by proglacial lakes affects salmon productivity, with particular reference to the Kenai River. Salmon escapement per unit channel length on the Kenai River is between two and ten times that found for rain-and-snowmelt dominated rivers and glacier-fed rivers lacking lake regulation. Lakes are shown to influence biological processes in glacier-fed rivers by attenuating peak flows, sustaining high flows throughout the summer, supplementing winter low flows, settling suspended sediment, and increasing river temperatures. Downstream from large lakes, glacier-fed rivers are less disturbed, channels are relatively stable and have well-developed salmonid habitats. The positive influences are indicated by the high diversity and abundances of benthic macroinvertebrates, which are important food resources for juvenile salmonids. High summer flows allow access for up-river salmon runs and lakes also provide both overwintering and rearing habitat. Copyright ?? 2000 John Wiley & Sons, Ltd.Rivers fed by glaciers constitute a major part of the freshwater runoff into the Cook Inlet basin of south-central Alaska. This basin is very important to the economy of the State of Alaska because it is home to more than half of the population and it supports multi-million dollar commercial, subsistence and sport fisheries. Hence an understanding of how glacial runoff influences biological productivity is important for managing rivers that drain into Cook Inlet

  9. Tree-ring isotopes reveal drought sensitivity in trees killed by spruce beetle outbreaks in south-central Alaska.

    PubMed

    Csank, Adam Z; Miller, Amy E; Sherriff, Rosemary L; Berg, Edward E; Welker, Jeffrey M

    2016-10-01

    Increasing temperatures have resulted in reduced growth and increased tree mortality across large areas of western North American forests. We use tree-ring isotope chronologies (δ(13) C and δ(18) O) from live and dead trees from four locations in south-central Alaska, USA, to test whether white spruce trees killed by recent spruce beetle (Dendroctonus rufipennis Kirby) outbreaks showed evidence of drought stress prior to death. Trees that were killed were more sensitive to spring/summer temperature and/or precipitation than trees that survived. At two of our sites, we found greater correlations between the δ(13) C and δ(18) O chronologies and spring/summer temperatures in dead trees than in live trees, suggesting that trees that are more sensitive to temperature-induced drought stress are more likely to be killed. At one site, the difference between δ(13) C in live and dead trees was related to winter/spring precipitation, with dead trees showing stronger correlations between δ(13) C and precipitation, again suggesting increased water stress in dead trees. At all sites where δ(18) O was measured, δ(18) O chronologies showed the greatest difference in climate response between live and dead groups, with δ(18) O in live trees correlating more strongly with late winter precipitation than dead trees. Our results indicate that sites where trees are already sensitive to warm or dry early growing-season conditions experienced the most beetle-kill, which has important implications for forecasting future mortality events in Alaska.

  10. Density and magnetic suseptibility values for rocks in the Talkeetna Mountains and adjacent region, south-central Alaska

    USGS Publications Warehouse

    Sanger, Elizabeth A.; Glen, Jonathan M.G.

    2003-01-01

    This report presents a compilation and statistical analysis of 306 density and 706 magnetic susceptibility measurements of rocks from south-central Alaska that were collected by U.S. Geological Survey (USGS) and Alaska Division of Geological and Geophysical Surveys (ADGGS) scientists between the summers of 1999 and 2002. This work is a product of the USGS Talkeetna Mountains Transect Project and was supported by USGS projects in the Talkeetna Mountains and Iron Creek region, and by Bureau of Land Management (BLM) projects in the Delta River Mining District that aim to characterize the subsurface structures of the region. These data were collected to constrain potential field models (i.e., gravity and magnetic) that are combined with other geophysical methods to identify and model major faults, terrane boundaries, and potential mineral resources of the study area. Because gravity and magnetic field anomalies reflect variations in the density and magnetic susceptibility of the underlying lithology, these rock properties are essential components of potential field modeling. In general, the average grain density of rocks in the study region increases from sedimentary, felsic, and intermediate igneous rocks, to mafic igneous and metamorphic rocks. Magnetic susceptibility measurements performed on rock outcrops and hand samples from the study area also reveal lower magnetic susceptibilities for sedimentary and felsic intrusive rocks, moderate susceptibility values for metamorphic, felsic extrusive, and intermediate igneous rocks, and higher susceptibility values for mafic igneous rocks. The density and magnetic properties of rocks in the study area are generally consistent with general trends expected for certain rock types.

  11. Whole-rock chemical composition of some samples from two drill hole cores in the Capps coal field, Beluga coal area, south-central Alaska

    USGS Publications Warehouse

    Hinkley, T.K.; Smith, K.S.; Peard, J.L.; Tompkins, M.L.

    1982-01-01

    Whole-rock chemical analysis was done on samples from drill cores of rocks lying atop and between coal beds in the Beluga coal area, south-central Alaska. The samples were classified as sandstone, siltstone or claystone at time of hand specimen description. Chemical data were compared to those from corresponding rocks from other sites in the conterminous United States. The study supports the following conclusions: 1. The sample suites from the two cored Alaska holes, about 1 km apart, contrast sharply in their degree of lithologic differentiation, one having relatively purer sandstones and claystones, the other having more mixed rock types. This suggests that considerable variation occurs in depositional environments and, possibly, in rock chemistry over small distances in the Beluga coal area. 2. Hand specimen inspection is a reasonably reliable way of assigning names denoting the lithologic type of Alaska rocks, and thereby making broad predictions of their whole-rock chemistry.

  12. Rock-Eval pyrolysis and vitrinite reflectance results from the Sheep Creek 1 well, Susitna basin, south-central Alaska

    USGS Publications Warehouse

    Stanley, Richard G.; Lillis, Paul G.; Pawlewicz, Mark J.; Haeussler, Peter J.

    2014-01-01

    We used Rock-Eval pyrolysis and vitrinite reflectance to examine the petroleum source potential of rock samples from the Sheep Creek 1 well in the Susitna basin of south-central Alaska. The results show that Miocene nonmarine coal, carbonaceous shale, and mudstone are potential sources of hydrocarbons and are thermally immature with respect to the oil window. In the samples that we studied, coals are more organic-rich and more oil-prone than carbonaceous shales and silty mudstones, which appear to be potential sources of natural gas. Lithologically similar rocks may be present in the deeper parts of the subsurface Susitna basin located west of the Sheep Creek 1 well, where they may have been buried deeply enough to generate oil and (or) gas. The Susitna basin is sparsely drilled and mostly unexplored, and no commercial production of hydrocarbons has been obtained. However, the existence of potential source rocks of oil and gas, as shown by our Rock-Eval results, suggests that undiscovered petroleum accumulations may be present in the Susitna basin.

  13. Range overlap and individual movements during breeding season influence genetic relationships of caribou herds in south-central Alaska

    USGS Publications Warehouse

    Roffler, Gretchen H.; Adams, Layne G.; Talbot, Sandra L.; Sage, George K.; Dale, Bruce W.

    2012-01-01

    North American caribou (Rangifer tarandus) herds commonly exhibit little nuclear genetic differentiation among adjacent herds, although available evidence supports strong demographic separation, even for herds with seasonal range overlap. During 1997–2003, we studied the Mentasta and Nelchina caribou herds in south-central Alaska using radiotelemetry to determine individual movements and range overlap during the breeding season, and nuclear and mitochondrial DNA (mtDNA) markers to assess levels of genetic differentiation. Although the herds were considered discrete because females calved in separate regions, individual movements and breeding-range overlap in some years provided opportunity for male-mediated gene flow, even without demographic interchange. Telemetry results revealed strong female philopatry, and little evidence of female emigration despite overlapping seasonal distributions. Analyses of 13 microsatellites indicated the Mentasta and Nelchina herds were not significantly differentiated using both traditional population-based analyses and individual-based Bayesian clustering analyses. However, we observed mtDNA differentiation between the 2 herds (FSTM = 0.041, P

  14. Age-specific reproduction in female sea otters (Enhydra lutris) from south-central Alaska: analysis of reproductive tracts

    USGS Publications Warehouse

    Bodkin, James L.; Mulcahy, Daniel M.; Lensink, Calvin J.

    1993-01-01

    We estimated age at sexual maturity and age-specific reproductive rates by examining carcasses and reproductive tracts from 177 female sea otters (Enhydra lutris). Carcasses were recovered from south-central Alaska, Primarily from western Prince William Sound, as a result of the T/V Exxon Valdez oil spill in 1989. We found 65% of our sample to be sexually mature. Sexual maturity was first attained at age 2. The proportion of sexually mature animals increased from 30% at age 2 to 100% at age 5. Annual reproductive rates increased from 22% at age 2 to 78% at age 5 and remained relatively stable (75-88%) through to age 15. the sex ratio (female:male) of 49 fetal sea otters was 18:37 and differed significantly from parity. Females younger than 8 tended to produce more female fetuses, while older mothers did not. Our estimates of the reproductive characteristics of female sea otters obtained by examination of reproductive tracts were similiar to those reported in the literature based on in situ observations of marked individuals.

  15. Expanding Sloping bog Systems Under a Continental Climate in South-Central Alaska: Possible Causes and Carbon-Cycle Implications

    NASA Astrophysics Data System (ADS)

    Loisel, J.; Yu, Z.; Jones, M. C.; Booth, R. K.

    2008-12-01

    Boreal peatlands play a key role in the global carbon (C) cycle, as they have accumulated up to about a third of the global soil carbon during the Holocene. Whilst numerous peat-based paleoecological records have been published on boreal Canadian and Siberian peatlands, there are few detailed C accumulation history studies on Alaskan peatlands. Here we report our field observations and preliminary data along several transects from a sloping (blanket) bog complex in the Susitna Valley of south-central Alaska and discuss possible causes for their occurrence in this continental setting and for their recent expansion. We observed, in the field and from satellite images, the presence of extensive peatland complexes in the Susitna River watershed, including both minerotrophic and ombrotrophic peatlands. Six peat cores were collected from a vast (> 1 km2) sloping bog complex (with pH from 3.92 to 4.46), located at ~ 450 m altitude and ~ 120 km NW of Talkeetna. These cores show a clayey, thick (15-30 cm thick) tephra layer at ~ 60 cm below the peatland surface that is attributable to the Hayes volcano eruptions at 4.4-3.6 cal ka. Preliminary macrofossil analyses along these cores indicate a transition from eutrophic conditions before the tephra, to mesotrophic/oligotrophic conditions after the tephra. We suggest that the tephra layer may have modified hydrology and chemistry of the site and facilitated the development of a nutrient-poor system. Active paludification (i.e., lateral expansion) was also observed at the margins of these peatland complexes, suggesting ideal hydroclimatic conditions for peat accumulation at the present. Given that the modern climatic envelope of peatland distribution indicates that ombrotrophic mires (e.g., raised and blanket bogs) usually occur under higher mean annual precipitation than what is measured in the study region, we suggest that the hydroclimatic regime of these peatlands is determined by a complex interaction among local substrate

  16. Lithogeochemistry of mineralized and altered rock samples from the northern Talkeetna Mountains, south-central Alaska

    USGS Publications Warehouse

    Light, Thomas D.; Schmidt, Jeanine M.

    2011-01-01

    Mineralized and altered rock samples collected from the northern Talkeetna Mountains, Alaska, were analyzed by two different inductively coupled plasma atomic-emission spectrometry (ICP-AES) methods for as many as 44 elements; by fire assay and either direct-coupled plasma (DCP) or atomic absorption spectrophotometry (AAS) for gold (Au); by cold vapor atomic absorption (CVAA) for mercury (Hg); and by irradiated neutron activation analysis (INAA) for tungsten (W). The analytical results showed that some samples contain high values of multiple elements and may be potential indicators of hydrothermal mineralization in the area.

  17. Southeast Directed Thrusting Associated With the Leading Edge of the Wrangellia Composite Terrane: The Chulitna Block South Central Alaska.

    NASA Astrophysics Data System (ADS)

    Gilman, T. L.; Fisher, D.

    2005-12-01

    Structural mapping of the Chulitna block in south central Alaska reveals a regional scale southeast-vergent, anticline-syncline pair and a series of related southeast-directed thrusts that record the imbrication of the leading edge of the Wrangellia Composite Terrane (WCT). The Chulitna block has been recognized as an unusual Paleozoic through Mesozoic collage of oceanic and clastic rocks that are not found anywhere else in Alaska or the North American Cordilleran. The distribution of these rocks varies across strike from southeast to northwest. In the southeast portion of the field area the oceanic rocks are a Late Devonian (Famennian) ophiolitic sequence including highly sheared serpentinite that is typically altered to magnesite and quartz, basalt (occasionally pillowed), gabbro (with possible cumulate texture), and red radiolarian chert. In the northwest of the map area, the marine rocks are composed of pillow basalts, basalts, and weakly metamorphosed limestones with Norian age fossils. Trace element chemistry of the basalts has been likened to the Late Triassic Nikolai greenstone of the WCT (Clautice et al., 2001). Conformably overlying the oceanic rocks in the northwest of the map area are Triassic red colored conglomerates, sandstones, and siltstones. In the southeast of the field area, these Triassic red rocks unconformably overlie the ophiolitic sequence. The clasts of the Triassic red beds are primarily composed of the underlying red radiolarian chert, basalt, and serpentinite. The main structure in the map area is an anticline-syncline pair that folds all the strata within the Chulitna block. The structure has a steep overturned limb, with a wavelength of ~2 km and an amplitude of ~1 km. To the southeast, there are a pair of out-of-syncline thrusts that juxtapose the serpentinites with overlying units. Large asymmetric folds in the area show a reversal in vergence across the hinge of the larger scale anticline and syncline pair, suggesting they are

  18. Temporal trends (1992-2007) of perfluorinated chemicals in Northern Sea Otters (Enhydra lutris kenyoni) from South-Central Alaska.

    PubMed

    Hart, Kimberly; Gill, Verena A; Kannan, Kurunthachalam

    2009-04-01

    Perfluorinated chemicals (PFCs) have been detected in abiotic and biotic matrices worldwide, including the Arctic Ocean. Considering these chemicals' persistent and bioaccumulative potentials, it was expected that levels of PFCs, like those of many legacy organic pollutants, would respond slowly to the restrictions in production and usage. Temporal trend studies in remote areas, such as the Arctic, can help determine the chronology of contamination and the response of the environment to regulations on PFCs. Prior to this study, temporal trends of PFCs in Alaskan coastal waters had not been examined. In the present study, concentrations of six PFCs were determined in livers of northern sea otters (Enhydra lutris kenyoni) collected from three areas in south-central Alaska (Prince William Sound, n = 36; Resurrection Bay, n = 7; Kachemak Bay, n = 34) from 1992 to 2007. Additionally, previously published profiles and concentrations of PFCs in southern sea otters from California and Asian sea otters from Kamchatka (Russia) were compared to our new data, to determine the geographical differences in PFC profiles among these three regions in the Pacific Ocean. Perfluorooctanesulfonate (PFOS), perfluorooctanesulfonamide (PFOSA), and perfluorononanoate (PFNA) were the predominant PFCs found in the livers of northern sea otters from 1992 to 2007. Other PFCs, such as perfluorooctanoate (PFOA), perfluoroundecanoate (PFUnDA), and perfluorodecanoate (PFDA), were detected less frequently, and at low concentrations. Overall, from 2001 to 2007, a decrease in concentrations of PFOS was found in northern sea otters, suggesting an immediate response to the phase-out in 2000 of perfluorooctanesulfonyl-based compounds by a major producer in the United States. In contrast, concentrations of PFNA in northern sea otters increased by 10-fold from 2004 to 2007. These results indicate that the contribution by PFNA to SigmaPFC concentrations is increasing in northern sea otters. The profiles (i

  19. Population genetic structure of moose (Alces Alces) of South-central Alaska.

    USGS Publications Warehouse

    Wilson, Robert E.; McDonough, John T.; Barboza, Perry S.; Talbot, Sandra L.; Farley, Sean D.

    2015-01-01

    The location of a population can influence its genetic structure and diversity by impacting the degree of isolation and connectivity to other populations. Populations at range margins areoften thought to have less genetic variation and increased genetic structure, and a reduction in genetic diversity can have negative impacts on the health of a population. We explored the genetic diversity and connectivity between 3 peripheral populations of moose (Alces alces) with differing potential for connectivity to other areas within interior Alaska. Populations on the Kenai Peninsula and from the Anchorage region were found to be significantly differentiated (FST= 0.071, P < 0.0001) with lower levels of genetic diversity observed within the Kenai population. Bayesian analyses employing assignment methodologies uncovered little evidence of contemporary gene flow between Anchorage and Kenai, suggesting regional isolation. Although gene flow outside the peninsula is restricted, high levels of gene flow were detected within the Kenai that is explained by male-biased dispersal. Furthermore, gene flow estimates differed across time scales on the Kenai Peninsula which may have been influenced by demographic fluctuations correlated, at least in part, with habitat change.

  20. Postglacial vegetation history of the Kachemak Bay area, Cook Inlet, south-central Alaska: A section in Geologic studies in Alaska by the U.S. Geological Survey, 1998

    USGS Publications Warehouse

    Ager, Thomas A.

    2000-01-01

    Pollen records from two sites on the north shore of Kachemak Bay, south-central Alaska, provide the first radiocarbon-dated histories of postglacial vegetation development for southern Cook Inlet. During the late Wisconsin glacial interval, glaciers covered most of Cook Inlet. Deglaciation of Kachemak Bay began prior to 13,000 yr B.P. Pollen evidence indicates that a pioneering herbaceous tundra began to develop by 12,800 yr B.P., but was soon replaced by a shrub tundra of dwarf birch (Betula), Ericales (Ericaceae and Empetrum) and willows (Salix).By 9,500 yr B.P., a shrub-dominated vegetation of alders (Alnus) and willows, with some deciduous trees (Populus spp.) quickly developed and persisted until late Holocene time. By about 4,000–3,800 yr B.P., spruce trees (Picea glauca and (or) P. mariana) from the interior boreal forests reached the northern Kachemak Bay area from upper Cook Inlet and began to displace the alder-dominated vegetation. A coastal forest of Sitka spruce (Picea sitchensis) began to colonize Kachemak Bay more recently, about 1,650 yr B.P. (minimum age), apparently from sources in Prince William Sound to the east. Where Sitka spruce came into proximity with boreal white spruce (Picea glauca), hybridization occurred, ultimately influencing the spruce forests over a large area of the Kenai Lowland. Some key findings of this study are: (1) the Kachemak Bay-area pollen records do not display persuasive evidence for a “Younger Dryas” cold, dry interval ca. 11,000–10,000 yr B.P. that has been reported from pollen records on Kodiak Island (Gulf of Alaska) and Pleasant Island (southeastern Alaska); (2) at least one species of alder may have survived in refugia in south-central Alaska during the last glacial interval; (3) coastal forests appear to be still migrating west along the coast of south-central Alaska, but their spread northward is being limited by drier, colder winter climates; (4) the mountainous topography of south-central Alaska

  1. Preliminary interpretation of industry two-dimensional seismic data from Susitna Basin, south-central Alaska

    USGS Publications Warehouse

    Lewis, Kristen A.; Potter, Christopher J.; Shah, Anjana K.; Stanley, Richard G.; Haeussler, Peter J.; Saltus, Richard W.

    2015-07-30

    The eastern seismic lines show evidence of numerous short-wavelength antiforms that appear to correspond to a series of northeast-trending lineations observed in aeromagnetic data, which have been interpreted as being due to folding of Paleogene volcanic strata. The eastern side of the basin is also cut by a number of reverse faults and thrust faults, the majority of which strike north-south. The western side of the Susitna Basin is cut by a series of regional reverse faults and is characterized by synformal structures in two fault blocks between the Kahiltna River and Skwentna faults. These synforms are progressively deeper to the west in the footwalls of the east-vergent Skwentna and northeast-vergent Beluga Mountain reverse faults. Although the seismic data are limited to the south, we interpret a potential regional south-southeast-directed reverse fault striking east-northeast on the east side of the basin that may cross the entire southern portion of the basin.

  2. Distribution, facies, ages, and proposed tectonic associations of regionally metamorphosed rocks in east- and south-central Alaska

    USGS Publications Warehouse

    Dusel-Bacon, Cynthia; Csejtey, Bela; Foster, Helen L.; Doyle, Elizabeth O.; Nokleberg, Warren J.; Plafker, George

    1993-01-01

    Most of the exposed bedrock in east- and south-central Alaska has been regionally metamorphosed and deformed during Mesozoic and early Cenozoic time. All the regionally metamorphosed rocks are assigned to metamorphic-facies units on the basis of their temperature and pressure conditions and metamorphic age. North of the McKinley and Denali faults, the crystalline rocks of the Yukon- Tanana upland and central Alaska Range compose a sequence of dynamothermally metamorphosed Paleozoic and older(?) metasedimentary rocks and metamorphosed products of a Devonian and Mississippian continental-margin magmatic arc. This sequence was extensively intruded by postmetamorphic mid-Cretaceous and younger granitoids. Many metamorphic-unit boundaries in the Yukon-Tanana upland are low-angle faults that juxtapose units of differing metamorphic grade, which indicates that metamorphism predated final emplacement of the fault-bounded units. In some places, the relation of metamorphic grade across a fault is best explained by contractional faulting; in other places, it is suggestive of extensional faulting.Near the United States-Canadian border in the central Yukon- Tanana upland, metamorphism, plutonism, and thrusting occurred during a latest Triassic and Early Jurassic event that presumably resulted from the accretion of a terrane that had affinities to the Stikinia terrane onto the continental margin of North America. Elsewhere in the Yukon-Tanana upland, metamorphic rocks give predominantly late Early Cretaceous isotopic ages. These ages are interpreted to date either the timing of a subsequent Early Cretaceous episode of crustal thickening and metamorphism or, assuming that these other areas were also originally heated during the latest Triassic to Early Jurassic and remained buried, the timing of their uplift and cooling. This uplift and cooling may have resulted from extension.South of the McKinley and Denali faults and north of the Border Ranges fault system, medium

  3. Paleomagnetism of Cretaceous and Paleocene sedimentary rocks across the Castle Mountain Fault, south central Alaska

    NASA Astrophysics Data System (ADS)

    Stamatakos, John A.; Kodama, K. P.; Vittorio, L. F.; Pavlis, T. L.

    Paleomagnetic and rock magnetic analyses on 217 samples from 13 sites in the Paleocene Chickaloon Formation south of the Castle Mountain Fault and 111 samples from 9 sites in the coeval, but lithologically distinct, Arkose Ridge Formation north of this fault indicate that these rocks contain a pre-folding magnetization carried by fine grained (<1.0μm) single domain magnetite. Secondary magnetizations are common, possibly as the result of the presence of authigenic or hydrothermal pyrrhotite. Although characteristic magnetizations were isolated for the Chickaloon and Arkose Ridge rocks, the best results were obtained from demagnetization plane analysis which estimates the location of the paleomagnetic pole for the Chickaloon Formation at 50.5°N, 277.2°E, δm = 12.2°, δP = 7.77deg;, and a paleomagnetic pole for the Arkose Ridge Formation at 60.4°N, 138.6°E, δm = 11.6°, δp = 6.4°. These results suggest that there is no paleomagnetically discernible latitudinal offset across the Castle Mountain Fault since Paleocene time, but that both the Chickaloon and Arkose Ridge rocks, as part of the Peninsular terrane, originated approximately 1600±1200 km south of their present position with respect to North America. One possible explanation of these data is that the Peninsular terrane was accreted to North America at mid-latitudes in the Cretaceous and was subsequently translated northward by right-lateral strike-slip faulting parallel to the North American margin. Hence, the Arkose Ridge and Chickaloon results may be indicative of the cumulative right-hand displacement occurring on these faults since Paleocene time. However, a calculation using the pole to the small circle fit of the present-day curvature of the Tintina-Northern Rocky Mountain Trench and Denali fault systems, and the maximum amount of structurally estimated offset across these fault systems, indicates that motion on these faults can account for no more than half of the paleomagnetically observed

  4. Genetic characterization of Kenai brown bears (Ursus arctos): Microsatellite and mitochondrial DNA control region variation in brown bears of the Kenai Peninsula, south central Alaska

    USGS Publications Warehouse

    Jackson, J.V.; Talbot, S.L.; Farley, S.

    2008-01-01

    We collected data from 20 biparentally inherited microsatellite loci, and nucleotide sequence from the maternally inherited mitochondrial DNA (mtDNA) control region, to determine levels of genetic variation of the brown bears (Ursus arctos L., 1758) of the Kenai Peninsula, south central Alaska. Nuclear genetic variation was similar to that observed in other Alaskan peninsular populations. We detected no significant inbreeding and found no evidence of population substructuring on the Kenai Peninsula. We observed a genetic signature of a bottleneck under the infinite alleles model (IAM), but not under the stepwise mutation model (SMM) or the two-phase model (TPM) of microsatellite mutation. Kenai brown bears have lower levels of mtDNA haplotypic diversity relative to most other brown bear populations in Alaska. ?? 2008 NRC.

  5. Field-trip guide to volcanic and volcaniclastic deposits of the lower Jurassic Talkeetna formation, Sheep Mountain, south-central Alaska

    USGS Publications Warehouse

    Draut, Amy E.; Clift, Peter D.; Blodgett, Robert B.

    2006-01-01

    This guide provides information for a one-day field trip in the vicinity of Sheep Mountain, just north of the Glenn Highway in south-central Alaska. The Lower Jurassic Talkeetna Formation, consisting of extrusive volcanic and volcaniclastic sedimentary rocks of the Talkeetna arc complex, is exposed on and near Sheep Mountain. Field-trip stops within short walking distance of the Glenn Highway (approximately two hours’ drive from Anchorage) are described, which will be visited during the Geological Society of America Penrose meeting entitled Crustal Genesis and Evolution: Focus on Arc Lower Crust and Shallow Mantle, held in Valdez, Alaska, in July 2006. Several additional exposures of the Talkeetna Formation on other parts of Sheep Mountain that would need to be accessed with longer and more strenuous walking or by helicopter are also mentioned.

  6. Effects of the March 1964 Alaska earthquake on the hydrology of south-central Alaska: Chapter A in The Alaska earthquake, March 27, 1964: effects on hydrologic regimen

    USGS Publications Warehouse

    Waller, Roger M.

    1966-01-01

    The earthquake of March 27, 1964, greatly affected the hydrology of Alaska and many other parts of the world. Its far-reaching effects were recorded as water-level fluctuations in gages operated on water wells and streams. The close-in effects were even more striking, however; sediment-laden ground water erupted at the surface, and even ice-covered lakes and streams responded by seiching. Lake and river ice was broken for distances of 450 miles from the epicenter by seismic shock and seiche action. The surging action temporarily dewatered some lakes. Fissuring of streambeds and lakeshores, in particular, caused a loss of water, and hydrologic recovery took weeks in some places. Landslides and snow avalanches temporarily blocked streams and diverted some permanently. The only stream or lake structures damaged were a tunnel intake and two earthen dams. The winter conditions-low stages of water and the extensive ice cover on lakes and streams-at the time of the earthquake greatly reduced the damaging potential. Ground water was drastically affected mostly in unconsolidated aquifers for at least 160 miles from the epicenter. Within 100 miles of the epicenter, vast quantities of sediment-laden water were ejected in most of the flood plains of the glaciofluvial valleys. A shallow water table and confinement by frost seemed to be requirements for the ejections, which were commonly associated with cratering and subsidence of the unconsolidated material. Subsidence was also common near the disastrous submarine landslides, and was probably caused by loss of water pressure and by lateral spreading of sediments. Effects on ground water in bedrock were not determinable because of lack of data and accessibility, particularly within 50 miles of the epicenter. Deep aquifers in unconsolidated sediments, which in most areas are under high hydrostatic pressure, were also greatly affected. Postearthquake water levels for a year were compared with long-term prequake levels to show

  7. Frozen debris lobes, permafrost slope instability, and a potential infrastructure hazard in the south-central Brooks Range of Alaska

    NASA Astrophysics Data System (ADS)

    Daanen, R. P.; Darrow, M.; Grosse, G.; Jones, B. M.

    2012-12-01

    Here we report on investigations carried out at unusual debris mass-movement features (frozen debris lobes) on permafrost slopes in the south central portion of the Brooks Range of northern Alaska. The features under investigation are located in mountainous terrain near the southern border of continuous permafrost. The frozen debris lobes consist mainly of boulders, cobles, platy gravel sand and silt frozen debris derived from weathering mountain tops. The general dimensions of these lobes are either lobate or tongue shaped with widths up to 500 m and lengths up to 1200 m. In accumulation zones where slopes converge, the debris slowly moves as solifluction lobes, mud flows and potentially sliding toward the valley. These features were previously referred to as stable rock glaciers in the past, as evidenced by a dense cover of vegetation, and exhibiting no known downslope movement. Our investigations however, have shown that these features are indeed moving downslope as a result of creep, slumping, viscous flow, blockfall and leaching of fines in the summer; and in cold seasons by creep and sliding of frozen sediment slabs. Movement indicators observed in the field include toppling trees, slumps and scarps, detachment slides, striation marks on frozen sediment slabs, recently buried trees and other vegetation, mudflows, and large cracks in the lobe surface. Ground-based measurements on one frozen debris-lobe over three years (2008-2010) revealed average movement rates of approximately 1 cm day-1, which is substantially larger than rates measured in historic aerial photography from the 1950s to 1980s. Current observations , through lidar, ifsar, insar and ground based measurements using boreholes, geophysics and repeat photography of these features show an increase in movement activity that could be the result of rising summer temperatures in the region. Warming of ice rich permafrost slopes and frozen debris lobes in the Brooks Range pose a direct threat to the

  8. Principal facts for 408 gravity stations in the vicinity of the Talkeetna Mountains, south-central Alaska

    USGS Publications Warehouse

    Morin, Robert L.; Glen, Jonathan M.G.

    2003-01-01

    Gravity data were collected between 1999 and 2002 along transects in the Talkeetna Mountains of south-central Alaska as part of a geological and geophysical study of the framework geology of the region. The study area lies between 61° 30’ and 63° 45’ N. latitude and 145° and 151° W. longitude. This data set includes 408 gravity stations. These data, combined with the pre-existing 3,286 stations, brings the total data in this area to 3,694 gravity stations. Principal facts for the 408 new gravity stations and the 15 gravity base stations used for control are listed in this report. During the summer of 1999, a gravity survey was conducted in the western Talkeetna Mountains. Measurements at 55 gravity stations were made. One gravity base station was used for control for this survey. This base station, STEP, is located at the Stephan Lake Lodge on Stephan Lake. The observed gravity of this station was calculated based on an indirect tie to base station ANCL in Anchorage. The temporary base used to tie between STEP and ANCL was REGL in Anchorage. During the summer of 2000, a gravity survey was conducted in the western Talkeetna Mountains. Measurements at 56 gravity stations were made. One gravity base station was used for control for this survey. This base station, GRHS, is located at the Gracious House Lodge on the Denali Highway. The observed gravity of this station was calculated based on multiple ties to base stations D87, and D57 along the Denali Highway. During the summer of 2001, a gravity survey was conducted in the western Talkeetna Mountains. Measurements at 90 gravity stations were made. One gravity base station was used for control for this survey. This base station, HLML, is located at the High Lake Lodge. The observed gravity of this station was calculated based on multiple ties to base stations ANCU in Anchorage, PALH in Palmer, WASA in Wasilla, and TLKM in Talkeetna. Also during the summer of 2001, a gravity survey was conducted in the vicinity

  9. Role of lake regulation on glacier-fed rivers in enhancing salmon productivity: the Cook Inlet watershed, south-central Alaska, USA

    NASA Astrophysics Data System (ADS)

    Dorava, Joseph M.; Milner, Alexander M.

    2000-10-01

    Rivers fed by glaciers constitute a major part of the freshwater runoff into the Cook Inlet basin of south-central Alaska. This basin is very important to the economy of the State of Alaska because it is home to more than half of the population and it supports multi-million dollar commercial, subsistence and sport fisheries. Hence an understanding of how glacial runoff influences biological productivity is important for managing rivers that drain into Cook Inlet. This paper examines the ways in which the regulation of glacier-fed rivers by proglacial lakes affects salmon productivity, with particular reference to the Kenai River. Salmon escapement per unit channel length on the Kenai River is between two and ten times that found for rain-and-snowmelt dominated rivers and glacier-fed rivers lacking lake regulation.Lakes are shown to influence biological processes in glacier-fed rivers by attenuating peak flows, sustaining high flows throughout the summer, supplementing winter low flows, settling suspended sediment, and increasing river temperatures. Downstream from large lakes, glacier-fed rivers are less disturbed, channels are relatively stable and have well-developed salmonid habitats. The positive influences are indicated by the high diversity and abundances of benthic macroinvertebrates, which are important food resources for juvenile salmonids. High summer flows allow access for up-river salmon runs and lakes also provide both overwintering and rearing habitat.

  10. Rapid movement of frozen debris-lobes: implications for permafrost degradation and slope instability in the south-central Brooks Range, Alaska

    USGS Publications Warehouse

    Daanen, R.P.; Grosse, G.; Darrow, M.M.; Hamilton, T.D.; Jones, Benjamin M.

    2012-01-01

    We present the results of a reconnaissance investigation of unusual debris mass-movement features on permafrost slopes that pose a potential infrastructure hazard in the south-central Brooks Range, Alaska. For the purpose of this paper, we describe these features as frozen debris-lobes. We focus on the characterisation of frozen debris-lobes as indicators of various movement processes using ground-based surveys, remote sensing, field and laboratory measurements, and time-lapse observations of frozen debris-lobe systems along the Dalton Highway. Currently, some frozen debris-lobes exceed 100 m in width, 20 m in height and 1000 m in length. Our results indicate that frozen debris-lobes have responded to climate change by becoming increasingly active during the last decades, resulting in rapid downslope movement. Movement indicators observed in the field include toppling trees, slumps and scarps, detachment slides, striation marks on frozen sediment slabs, recently buried trees and other vegetation, mudflows, and large cracks in the lobe surface. The type and diversity of observed indicators suggest that the lobes likely consist of a frozen debris core, are subject to creep, and seasonally unfrozen surface sediment is transported in warm seasons by creep, slumping, viscous flow, blockfall and leaching of fines, and in cold seasons by creep and sliding of frozen sediment slabs. Ground-based measurements on one frozen debris-lobe over three years (2008–2010) revealed average movement rates of approximately 1 cm day−1, which is substantially larger than rates measured in historic aerial photography from the 1950s to 1980s. We discuss how climate change may further influence frozen debris-lobe dynamics, potentially accelerating their movement. We highlight the potential direct hazard that one of the studied frozen debris-lobes may pose in the coming years and decades to the nearby Trans Alaska Pipeline System and the Dalton Highway, the main artery for transportation

  11. Rapid movement of frozen debris-lobes: implications for permafrost degradation and slope instability in the south-central Brooks Range, Alaska

    NASA Astrophysics Data System (ADS)

    Daanen, R. P.; Grosse, G.; Darrow, M. M.; Hamilton, T. D.; Jones, B. M.

    2012-05-01

    We present the results of a reconnaissance investigation of unusual debris mass-movement features on permafrost slopes that pose a potential infrastructure hazard in the south-central Brooks Range, Alaska. For the purpose of this paper, we describe these features as frozen debris-lobes. We focus on the characterisation of frozen debris-lobes as indicators of various movement processes using ground-based surveys, remote sensing, field and laboratory measurements, and time-lapse observations of frozen debris-lobe systems along the Dalton Highway. Currently, some frozen debris-lobes exceed 100 m in width, 20 m in height and 1000 m in length. Our results indicate that frozen debris-lobes have responded to climate change by becoming increasingly active during the last decades, resulting in rapid downslope movement. Movement indicators observed in the field include toppling trees, slumps and scarps, detachment slides, striation marks on frozen sediment slabs, recently buried trees and other vegetation, mudflows, and large cracks in the lobe surface. The type and diversity of observed indicators suggest that the lobes likely consist of a frozen debris core, are subject to creep, and seasonally unfrozen surface sediment is transported in warm seasons by creep, slumping, viscous flow, blockfall and leaching of fines, and in cold seasons by creep and sliding of frozen sediment slabs. Ground-based measurements on one frozen debris-lobe over three years (2008-2010) revealed average movement rates of approximately 1 cm day-1, which is substantially larger than rates measured in historic aerial photography from the 1950s to 1980s. We discuss how climate change may further influence frozen debris-lobe dynamics, potentially accelerating their movement. We highlight the potential direct hazard that one of the studied frozen debris-lobes may pose in the coming years and decades to the nearby Trans Alaska Pipeline System and the Dalton Highway, the main artery for transportation

  12. Effects of the earthquake of March 27, 1964, on air and water transport, communications, and utilities systems in south-central Alaska: Chapter B in The Alaska earthquake, March 27, 1964: effects on transportation, communications, and utilities

    USGS Publications Warehouse

    Eckel, Edwin B.

    1967-01-01

    The earthquake of March 27, 1964, wrecked or severely hampered all forms of transportation, all utilities, and all communications systems over a very large part of south-central Alaska. Effects on air transportation were minor as compared to those on the water, highway, and railroad transport systems. A few planes were damaged or wrecked by seismic vibration or by flooding. Numerous airport facilities were damaged by vibration or by secondary effects of the earthquake, notably seismic sea and landslide-generated waves, tectonic subsidence, and compaction. Nearly all air facilities were partly or wholly operational within a few hours after the earthquake. The earthquake inflicted enormous damage on the shipping industry, which is indispensable to a State that imports fully 90 percent of its requirements—mostly by water—and whose largest single industry is fishing. Except for those of Anchorage, all port facilities in the earthquake-affected area were destroyed or made inoperable by submarine slides, waves, tectonic uplift, and fire. No large vessels were lost, but more than 200 smaller ones (mostly crab or salmon boats) were lost or severely damaged. Navigation aids were destroyed, and hitherto well-known waterways were greatly altered by uplift or subsidence. All these effects wrought far-reaching changes in the shipping economy of Alaska, many of them to its betterment. Virtually all utilities and communications in south-central Alaska were damaged or wrecked by the earthquake, but temporary repairs were effected in remarkably short times. Communications systems were silenced almost everywhere by loss of power or by downed lines; their place was quickly taken by a patchwork of self-powered radio transmitters. A complex power-generating system that served much of the stricken area from steam, diesel, and hydrogenerating plants was disrupted in many places by vibration damage to equipment and by broken transmission lines. Landslides in Anchorage broke gas

  13. A deglacial and Holocene record of climate variability in south-central Alaska from stable oxygen isotopes and plant macrofossils in peat

    USGS Publications Warehouse

    Jones, Miriam C.; Wooller, Matthew J.; Peteet, Dorothy M.

    2014-01-01

    We used stable oxygen isotopes derived from bulk peat (δ18OTOM), in conjunction with plant macrofossils and previously published carbon accumulation records, in a ∼14,500 cal yr BP peat core (HT Fen) from the Kenai lowlands in south-central Alaska to reconstruct the climate history of the area. We find that patterns are broadly consistent with those from lacustrine records across the region, and agree with the interpretation that major shifts in δ18OTOM values indicate changes in strength and position of the Aleutian Low (AL), a semi-permanent low-pressure cell that delivers winter moisture to the region. We find decreased strength or a more westerly position of the AL (relatively higher δ18OTOM values) during the Bølling-Allerød, Holocene Thermal Maximum (HTM), and late Holocene, which also correspond to warmer climate regimes. These intervals coincide with greater peat preservation and enhanced carbon (C) accumulation rates at the HT Fen and with peatland expansion across Alaska. The HTM in particular may have experienced greater summer precipitation as a result of an enhanced Pacific subtropical high, a pattern consistent with modern δ18O values for summer precipitation. The combined warm summer temperatures and greater summer precipitation helped promote the observed rapid peat accumulation. A strengthened AL (relatively lower δ18OTOM values) is most evident during the Younger Dryas, Neoglaciation, and the Little Ice Age, consistent with lower peat preservation and C accumulation at the HT Fen, suggesting less precipitation reaches the leeward side of the Kenai Mountains during periods of enhanced AL strength. The peatlands on the Kenai Peninsula thrive when the AL is weak and the contribution of summer precipitation is higher, highlighting the importance of precipitation seasonality in promoting peat accumulation. This study demonstrates that δ18OTOM values in peat can be applied toward understand large-scale shifts in atmospheric circulation

  14. Isotopic ages from intrusive rocks near the Stuyahok gold placer deposits, south-central Holy Cross quadrangle, Alaska: A section in Geologic studies in Alaska by the U.S. Geological Survey, 1998

    USGS Publications Warehouse

    Miller, Marti L.; Tucker, Robert D.; Layer, Paul W.; Bundtzen, Thomas K.

    2000-01-01

    In the Stuyahok area of the south-central Holy Cross quadrangle, Alaska, felsic to intermediate dikes and sills intrude Lower Cretaceous volcanic and volcaniclastic rocks of the Koyukuk terrane. These previously undated intrusions are the probable source of at least 933 kg (30,000 oz) of past placer gold production. Additional placer, and perhaps lode, resources are likely present at Stuyahok. New U/Pb and 40Ar/39Ar isotopic data indicate two of the dikes are early Tertiary in age (63.6+0.2 Ma and 60.4+1.1 Ma, respectively). In addition to helping constrain the age of gold mineralization, these early Tertiary ages suggest the Stuyahok dikes are part of a Late Cretaceous and early Tertiary belt of gold mineralized felsic dikes that lie in the Kuskokwim mineral belt. Also reported herein are previously unpublished conventional K-Ar ages of 69.4+2.1 Ma and 69.3+2.1 Ma for two felsic intrusions from the western edge of this mineralized belt, the Marshall–Kako Creek area, which lies about 40 km west-southwest of the Stuyahok area.

  15. Kittlitz's and Marbled Murrelets in Kenai Fjords National Park, South-Central Alaska: At-Sea Distribution, Abundance, and Foraging Habitat, 2006-08

    USGS Publications Warehouse

    Arimitsu, M.L.; Piatt, J.F.; Romano, Marc D.; Madison, E.N.; Conaway, J.S.

    2010-01-01

    Kittlitz's murrelets (Brachyramphus brevirostris) and marbled murrelets (B. marmoratus) are small diving seabirds and are of management concern because of population declines in coastal Alaska. In 2006-08, we conducted a study in Kenai Fjords National Park, south-central Alaska, to estimate the recent population size of Brachyramphus murrelets, to evaluate productivity based on juvenile to adult ratios during the fledgling season, and to describe and compare their use of marine habitat. We also attempted a telemetry study to examine Kittlitz's murrelet nesting habitat requirements and at-sea movements. We estimated that the Kittlitz's murrelet population was 671 ? 144 birds, and the marbled murrelet population was 5,855 ? 1,163 birds. Kittlitz's murrelets were limited to the heads of three fjords with tidewater glaciers, whereas marbled murrelets were more widely distributed. Population estimates for both species were lower in 2007 than in 2006 and 2008, possibly because of anomalous oceanographic conditions that may have delayed breeding phenology. During late season surveys, we observed few hatch-year marbled murrelets and only a single hatch-year Kittlitz's murrelet over the course of the study. Using radio telemetry, we found a likely Kittlitz's murrelet breeding site on a mountainside bordering one of the fjords. We never observed radio-tagged Kittlitz's murrelets greater than 10 kilometer from their capture sites, suggesting that their foraging range during breeding is narrow. We observed differences in oceanography between fjords, reflecting differences in sill characteristics and orientation relative to oceanic influence. Acoustic biomass, a proxy for zooplankton and small schooling fish, generally decreased with distance from glaciers in Northwestern Lagoon, but was more variable in Aialik Bay where dense forage fish schools moved into glacial areas late in the summer. Pacific herring (Clupea pallasii), capelin (Mallotus villosus) and Pacific sand lance

  16. A Deglacial and Holocene Record of Climate Variability in South-Central Alaska from Stable Oxygen Isotopes and Plant Macrofossils in Peat

    NASA Technical Reports Server (NTRS)

    Jones, Miriam C.; Wooller, Matthew; Peteet, Dorothy M.

    2014-01-01

    We used stable oxygen isotopes derived from bulk peat (delta-O-18(sub TOM) in conjunction with plant macrofossils and previously published carbon accumulation records, in a approximately14,500 cal yr BP peat core (HT Fen) from the Kenai lowlands in south-central Alaska to reconstruct the climate history of the area. We find that patterns are broadly consistent with those from lacustrine records across the region, and agree with the interpretation that major shifts in delta-O-18(sub TOM) values indicate changes in strength and position of the Aleutian Low (AL), a semi-permanent low-pressure cell that delivers winter moisture to the region. We find decreased strength or a more westerly position of the AL (relatively higher delta-O-18(sub TOM) values) during the Bolling-Allerod, Holocene Thermal Maximum (HTM), and late Holocene, which also correspond to warmer climate regimes. These intervals coincide with greater peat preservation and enhanced carbon (C) accumulation rates at the HT Fen and with peatland expansion across Alaska. The HTM in particular may have experienced greater summer precipitation as a result of an enhanced Pacific subtropical high, a pattern consistent with modern delta-O-18 values for summer precipitation. The combined warm summer temperatures and greater summer precipitation helped promote the observed rapid peat accumulation. A strengthened AL (relatively lower delta-O-18(sub TOM) values) is most evident during the Younger Dryas, Neoglaciation, and the Little Ice Age, consistent with lower peat preservation and C accumulation at the HT Fen, suggesting less precipitation reaches the leeward side of the Kenai Mountains during periods of enhanced AL strength. The peatlands on the Kenai Peninsula thrive when the AL is weak and the contribution of summer precipitation is higher, highlighting the importance of precipitation seasonality in promoting peat accumulation. This study demonstrates that delta-O-18(sub TOM) values in peat can be applied

  17. Field guide to the Mesozoic accretionary complex along Turnagain Arm and Kachemak Bay, south-central Alaska

    USGS Publications Warehouse

    Bradley, Dwight C.; Kusky, Timothy M.; Karl, Susan M.; Haeussler, Peter J.

    1997-01-01

    Turnagain Arm, just east of Anchorage, provides a readily accessible, world-class cross section through a Mesozoic accretionary wedge. Nearly continuous exposures along the Seward Highway, the Alaska Railroad, and the shoreline of Turnagain Arm display the two main constituent units of the Chugach terrane: the McHugh Complex and Valdez Group. In this paper we describe seven bedrock geology stops along Turnagain Arm, and two others in the Chugach Mountains just to the north (Stops 1-7 and 9), which will be visited as part of the May, 1997 field trip of the Alaska Geological Society. Outcrops along Turnagain Arm have already been described in two excellent guidebook articles (Clark, 1981; Winkler and others 1984), both of which remain as useful and valid today as when first published. Since the early 1980's, studies along Turnagain Arm have addressed radiolarian ages of chert and conodont ages of limestone in the McHugh Complex (Nelson and others, 1986, 1987); geochemistry of basalt in the McHugh Complex (Nelson and Blome, 1991); post-accretion brittle faulting (Bradley and Kusky, 1990; Kusky and others, 1997); and the age and tectonic setting of gold mineralization (Haeussler and others, 1995). Highlights of these newer findings will described both in the text below, and in the stop descriptions.Superb exposures along the southeastern shore of Kachemak Bay show several other features of the McHugh Complex that are either absent or less convincing along Turnagain Arm. While none of these outcrops can be reached via the main road network, they are still reasonably accessible - all are within an hour by motorboat from Homer, seas permitting. Here, we describe seven outcrops along the shore of Kachemak Bay that we studied between 1989 and 1993 during geologic mapping of the Seldovia 1:250,000- scale quadrangle. These outcrops (Stops 61-67) will not be part of the 1997 itinerary, but are included here tor the benefit of those who may wish to visit them later.

  18. Landslide Hazard Mapping Using Ground-based Interferometric Radar in the Fjords of South-Central Alaska

    NASA Astrophysics Data System (ADS)

    Balazs, M. S.; Meyer, F. J.; Bollian, T.; Wolken, G. J.; Prakash, A.

    2013-12-01

    The cities of Seward and Whittier, Alaska are situated at the base of steep walls within two fjords located on the Kenai Peninsula. Historic events have shown that the combination of terrain, geology, and vegetation are factors which can lead to significant events of erosion in the surrounding slopes during periods of heavy rainfall. While other remote sensing techniques have been shown to be useful for accessing landslide hazards, local surface processes may be better understood to create more accurate hazard maps and predictive models by using data gained from interferometric radar. To gain perspective into where, and at which speed, slopes are deforming, we utilize the GPRI-2 terrestrial interferometric radar system which transmits signals in the Ku band. The GPRI-2 portable radar unit has several advantages to space-borne radar, including relative freedom of site selection and regions to target, ability to determine temporal baselines, and repeat acquisitions which can be collected with a zero spatial-baseline. There are however, problems which need to be addressed when using such a system in the fjord environments, and in particular for monitoring slope deformation in these areas. Foremost, the noise that is attributed to the atmosphere is of great concern as it is sometimes required to position the radar several kilometers away from the target, across open water. We offer our results of correcting for this interference and report the results. Secondly, we address the issue of repeat acquisitions over long periods of time, which is needed to detect movements in the slope, and report on the decorrelation of the signal in the various land cover types in the study areas. Finally, we offer suggestions of the usefulness of such a system to detect slope deformation in similar environments.

  19. Summer dietary nitrogen availability as a potential bottom-up constraint on moose in south-central Alaska.

    PubMed

    McArt, Scott H; Spalinger, Donald E; Collins, William B; Schoen, Erik R; Stevenson, Timothy; Bucho, Michele

    2009-05-01

    Recent studies suggest that the growth and fecundity of northern ungulates may be coupled to their summer nutrition. Here, we compare summer dietary nitrogen availability of the five major browse plants (comprising approximately 79% of the diet) of moose (Alces alces) in Denali National Park and Nelchina Basin, Alaska, USA. In recent years the productivity of Denali moose has been significantly higher than that of Nelchina moose, prompting this comparison. We examined the phenological progression of leaf nitrogen concentration, tannin-protein precipitation capacity, and digestible protein over three summers in both regions. We then modeled the potential nutritional consequences for a cow moose consuming representative diets on each range, predicting both net protein intake (NPI) and lean body mass accumulation each year. We found that leaf nitrogen and digestible protein decreased, while tannin-protein precipitation capacity increased throughout the summer for all forages. There was 23% more digestible protein in Denali leaves than Nelchina leaves on average, and this difference was significant in all three years. Tannins accounted for a large (mean = 46%) reduction in protein availability, suggesting a key role of these secondary compounds in the nitrogen balance of moose in these regions. Finally, our NPI model predicted that Denali cows were in positive protein balance 17 days longer than Nelchina cows and accumulated 18 kg more lean body mass over the summer, on average. We conclude that summer dietary nitrogen availability may act as a nutritional constraint on moose and suggest that more emphasis be placed on elucidating its role in population dynamics and conservation of northern ungulates.

  20. Geologic Map of Central (Interior) Alaska

    USGS Publications Warehouse

    Wilson, Frederic H.; Dover, James H.; Bradley, Dwight C.; Weber, Florence R.; Bundtzen, Thomas K.; Haeussler, Peter J.

    1998-01-01

    Introduction: This map and associated digital databases are the result of a compilation and reinterpretation of published and unpublished 1:250,000- and limited 1:125,000- and 1:63,360-scale mapping. The map area covers approximately 416,000 sq km (134,000 sq mi) and encompasses 25 1:250,000-scale quadrangles in central Alaska. The compilation was done as part of the U.S. Geological Survey National Surveys and Analysis project, whose goal is nationwide assemble geologic, geochemical, geophysical, and other data. This map is an early product of an effort that will eventually encompass all of Alaska, and is the result of an agreement with the Alaska Department of Natural Resources, Division of Oil And Gas, to provide data on interior basins in Alaska. A paper version of the three map sheets has been published as USGS Open-File Report 98-133. Two geophysical maps that cover the identical area have been published earlier: 'Bouguer gravity map of Interior Alaska' (Meyer and others, 1996); and 'Merged aeromagnetic map of Interior Alaska' (Meyer and Saltus, 1995). These two publications are supplied in the 'geophys' directory of this report.

  1. Significance of a near-source tephra-stratigraphic sequence to the eruptive history of Hayes Volcano, south-central Alaska

    USGS Publications Warehouse

    Wallace, Kristi; Coombs, Michelle L.; Hayden, Leslie A.; Waythomas, Christopher F.

    2014-01-01

    Bluffs along the Hayes River valley, 31 km northeast and 40 km downstream from Hayes Volcano, reveal volcanic deposits that shed new light on its eruptive history. Three thick (>10 cm) and five thin (<10 cm) tephra-fall deposits are dacitic in whole rock composition and contain high proportions of amphibole to pyroxene and minor biotite and broadly correlate to Hayes tephra set H defined by earlier investigators. Two basal ages for the tephra-fall sequence of 3,690±30 and 3,750±30 14C yr B.P. are also consistent with the Hayes tephra set H timeframe. Distinguishing among Hayes tephra set H units is critical because the set is an important time-stratigraphic marker in south-central Alaska and this section provides a new reference section for Hayes tephra set H. Analysis of Fe-Ti oxide grains in the tephras shows promise for identifying individual Hayes deposits. Beneath the dacitic tephra sequence lies an older, poorly sorted tephra (tephra A) that contains dacite and rhyolite lapilli and whose basal age is 4,450±30 14C yr B.P. Immediately below the tephra-fall sequence (Unit III) lies a series of mass-flow deposits that are rich in rhyodacitic clasts (Unit II). Below Unit II and possibly coeval with it, is a 20–30 m thick pumiceous pyroclastic-flow deposit (Unit I) that extends to the valley floor. Here informally named the Hayes River ignimbrite, this deposit contains pumice clasts of rhyolite with quartz, sanidine, plagioclase, and biotite phenocrysts, an assemblage that is unique among known Quaternary volcanic products of Hayes and other Alaskan volcanoes. Units I, II, and tephra A of Unit III represent at least two previously unrecognized eruptions of Hayes Volcano that occurred prior to ~3,700 yr B.P. No compositionally equivalent distal tephra deposits correlative with Hayes Volcano rhyodacites or rhyolites have yet been identified, perhaps indicating that some of these deposits are pre-Holocene, and were largely removed by glacial ice during the last

  2. Assessment of the Coal-Bed Gas Total Petroleum System in the Cook Inlet-Susitna region, south-central Alaska

    USGS Publications Warehouse

    Rouse, William A.; Houseknecht, David W.

    2012-01-01

    The Cook Inlet-Susitna region of south-central Alaska contains large quantities of gas-bearing coal of Tertiary age. The U.S. Geological Survey in 2011 completed an assessment of undiscovered, technically recoverable coal-bed gas resources underlying the Cook Inlet-Susitna region based on the total petroleum system (TPS) concept. The Cook Inlet Coal-Bed Gas TPS covers about 9,600,000 acres and comprises the Cook Inlet basin, Matanuska Valley, and Susitna lowland. The TPS contains one assessment unit (AU) that was evaluated for coal-bed gas resources between 1,000 and 6,000 feet in depth over an area of about 8,500,000 acres. Coal beds, which serve as both the source and reservoir for natural gas in the AU, were deposited during Paleocene-Pliocene time in mires associated with a large trunk-tributary fluvial system. Thickness of individual coal beds ranges from a few inches to more than 50 feet, with cumulative coal thickness of more than 800 feet in the western part of the basin. Coal rank ranges from lignite to subbituminous, with vitrinite reflectance values less than 0.6 percent throughout much of the AU. The AU is considered hypothetical because only a few wells in the Matanuska Valley have tested the coal-bed reservoirs, so the use of analog coal-bed gas production data was necessary for this assessment. In order to estimate reserves that might be added in the next 30 years, coal beds of the Upper Fort Union Formation in the Powder River Basin of Wyoming and Montana were selected as the production analog for Tertiary coal beds in the Cook Inlet-Susitna region. Upper Fort Union coal beds have similar rank (lignite to subbituminous), range of thickness, and coal-quality characteristics as coal beds of the Tertiary Kenai Group. By use of this analog, the mean total estimate of undiscovered coal-bed gas in the Tertiary Coal-Bed Gas AU is 4.674 trillion cubic feet (TCF) of gas.

  3. Part I: Neoacadian to Alleghanian foreland basin development and provenance in the central appalachian orogen, pine mountain thrust sheet Part II: Structural configuration of a modified Mesozoic to Cenozoic forearc basin system, south-central Alaska

    NASA Astrophysics Data System (ADS)

    Robertson, Peter Benjamin

    Foreland and forearc basins are large sediment repositories that form in response to tectonic loading and lithospheric flexure during orogenesis along convergent plate boundaries. In addition to their numerous valuable natural resources, these systems preserve important geologic information regarding the timing and intensity of deformation, uplift and erosion history, and subsidence history along collisional margins, and, in ancient systems, may provide more macroscopic information regarding climate, plate motion, and eustatic sea level fluctuations. This thesis presents two studies focused in the Paleozoic Appalachian foreland basin system along the eastern United States and in the Mesozoic to Cenozoic Matanuska forearc basin system in south-central Alaska. Strata of the Appalachian foreland basin system preserve the dynamic history of orogenesis and sediment dispersal along the east Laurentian margin, recording multiple episodes of deformation and basin development during Paleozoic time. A well-exposed, >600 m thick measured stratigraphic section of the Pine Mountain thrust sheet at Pound Gap, Kentucky affords one of the most complete exposures of Upper Devonian through Middle Pennsylvanian strata in the basin. These strata provide a window into which the foreland basin's development during two major collisional events known as the Acadian-Neoacadian and the Alleghanian orogenies can be observed. Lithofacies analysis of four major sedimentary successions observed in hanging wall strata record the upward transition from (1) a submarine deltaic fan complex developed on a distal to proximal prodelta in Late Devonian to Middle Mississippian time, to (2) a Middle to Late Mississippian carbonate bank system developed on a slowly subsiding, distal foreland ramp, which was drowned by (3) Late Mississippian renewed clastic influx to a tidally influenced, coastal deltaic complex to fluvial delta plain system unconformably overlain by (4) a fluvial braided river complex

  4. Ordovician sponges from west-central and east-central Alaska and western Yukon Territory, Canada

    USGS Publications Warehouse

    Rigby, J.K.; Blodgett, R.B.; Britt, B.B.

    2008-01-01

    Moderate collections of fossil sponges have been recovered over a several-year period from a few scattered localities in west-central and east-central Alaska, and from westernmost Yukon Territory of Canada. Two fragments of the demosponge agelasiid cliefdenellid, Cliefdenella alaskaensis Stock, 1981, and mostly small unidentifiable additional fragments were recovered from a limestone debris flow bed in the White Mountain area, McGrath A-4 Quadrangle in west-central Alaska. Fragments of the agelasiid actinomorph girtyocoeliids Girtyocoeliana epiporata (Rigby & Potter, 1986) and Girtyocoelia minima n. sp., plus a specimen of the vaceletid colospongiid Corymbospongia amplia Rigby, Karl, Blodgett & Baichtal, 2005, were collected from probable Ashgillian age beds in the Livengood B-5 Quadrangle in east-central Alaska. A more extensive suite of corymbospongiids, including Corymbospongia betella Rigby, Potter & Blodgett, 1988, C. mica Rigby & Potter, 1986, and C.(?) perforata Rigby & Potter, 1986, along with the vaceletiid colospongiids Pseudo-imperatoria minima? (Rigby & Potter, 1986), and Pseudoimperatoria media (Rigby & Potter, 1986), and with the heteractinid Nucha naucum? Pickett & Jell, 1983, were recovered from uppermost part of the Jones Ridge Limestone (Ashgillian), on the south flank of Jones Ridge, in the Sheep Mountain Quadrangle, in westernmost Yukon Territory, Canada. The fossil sponges from the McGrath A-4 and Livengood B-5 quadrangles were recovered from attached Siberian terranes, and those from the Sheep Mountain Quadrangle were recovered from an allochthonous Laurentian terrane in the Yukon Territory.

  5. Placer tin deposits in central Alaska

    USGS Publications Warehouse

    Chapman, Robert Mills; Coats, Robert Roy; Payne, Thomas G.

    1963-01-01

    Placer tin, in the form of cassiterite (Sn02) and (or) tinstone (fragments including cassiterite and some vein or rock material), is known or reported in deposits that have been prospected or mined for placer gold in four areas adjacent to the Yukon River in central Alaska, 120 to 240 miles west of Fairbanks. These areas are: the Morelock Creek area, on the north side of the Yukon River about 30 miles upstream from Tanana; the Moran Dome area, about 16 miles north of the Yukon River and 25 miles northwest of Tanana; the Mason Creek area, on the north side of the Yukon River about 36 miles west of Tanana; and the Ruby-Long area, on the south side of the Yukon River near Ruby and about 40 miles east of Galena. The only extensive placer mining in these areas has been in the Ruby-Long area. Other placer deposits including some cassiterite are known in central Alaska but are not discussed in this report. Bedrock in these areas is predominantly schist of various types with some associated greenstone and other metamorphic rocks. Some granite is exposed in the Moran Dome and Ruby-Long areas and in areas close to Morelock and Mason Creeks. Barren, milky quartz veins and veinlets transecting the metamorphic rocks are common. No cassiterite was found in the bedrock, and no bedrock source of the tin has been reported. In the Moran Dome and Mason Creek areas, and in part of the Ruby-Long area, tourmaline is present in the rocks of the tin-bearing drainage basins, and apparently absent elsewhere in these areas. The placer deposits are in both valley floor and bench alluvium, which are predominantly relatively thin, rarely exceeding a thickness of 30 feet. Most of the alluvium deposits are not perennially frozen. In the Morelock Creek area tin-bearing deposits are 5 to 5? miles above the mouth of the creek, and meager evidence indicates that cassiterite and gold are present in Morelock Creek valley and some of the tributaries both upstream and downstream from these deposits. The

  6. U.S. Geological Survey 2011 assessment of undiscovered oil and gas resources of the Cook Inlet region, south-central Alaska

    USGS Publications Warehouse

    Stanley, Richard G.; Pierce, Brenda S.; Houseknecht, David W.

    2011-01-01

    The U.S. Geological Survey (USGS) has completed an assessment of the volumes of undiscovered, technically recoverable oil and gas resources in conventional and continuous accumulations in Cook Inlet. The assessment used a geology-based methodology and results from new scientific research by the USGS and the State of Alaska, Department of Natural Resources, Division of Geological and Geophysical Surveys and Division of Oil and Gas (DOG). In the Cook Inlet region, the USGS estimates mean undiscovered volumes of nearly 600 million barrels of oil, about 19 trillion cubic feet of gas, and about 46 million barrels of natural gas liquids.

  7. Stream-sediment samples reanalyzed for major, rare earth, and trace elements from ten 1:250,000-scale quadrangles, south-central Alaska, 2007-08

    USGS Publications Warehouse

    Bailey, Elizabeth A.; Shew, Nora B.; Labay, Keith A.; Schmidt, Jeanine M.; O'Leary, Richard M.; Detra, David E.

    2010-01-01

    During the 1960s through the 1980s, the U.S. Geological Survey (USGS) conducted reconnaissance geochemical surveys of the drainage basins throughout most of the Anchorage, Bering Glacier, Big Delta, Gulkana, Healy, McCarthy, Mount Hayes, Nabesna, Talkeetna Mountains, and Valdez 1:250,000-scale quadrangles in Alaska as part of the Alaska Mineral Resource Assessment Program (AMRAP). These geochemical surveys provide data necessary to assess the potential for undiscovered mineral resources on public and other lands, and provide data that may be used to determine regional-scale element baselines. This report provides new data for 366 of the previously collected stream-sediment samples. These samples were selected for reanalysis because recently developed analytical methods can detect additional elements of interest and have lower detection limits than the methods used when these samples were originally analyzed. These samples were all analyzed for arsenic by hydride generation atomic absorption spectrometry (HGAAS), for gold, palladium, and platinum by inductively coupled plasma-mass spectrometry after lead button fire assay separation (FA/ICP-MS), and for a suite of 55 major, rare earth, and trace elements by inductively coupled plasma-atomic emission spectrometry and inductively coupled plasma-mass spectrometry (ICP-AES-MS) after sodium peroxide sinter at 450 degrees Celsius.

  8. Stream-sediment samples reanalyzed for major, rare earth, and trace elements from seven 1:250,000-scale quadrangles, south-central Alaska, 2007-09

    USGS Publications Warehouse

    Gamble, Bruce M.; Bailey, Elizabeth A.; Shew, Nora B.; Labay, Keith A.; Schmidt, Jeanine M.; O'Leary, Richard M.; Detra, David E.

    2010-01-01

    During the 1960s through the 1980s, the U.S. Geological Survey conducted reconnaissance geochemical surveys of drainage basins throughout most of the Iliamna, Lake Clark, Lime Hills, and Talkeetna 1:250,000-scale quadrangles and parts of the McGrath, Seldovia, and Tyonek 1:250,000-scale quadrangles in Alaska. These geochemical surveys provide data necessary to assess the potential for undiscovered mineral resources and provide data that may be used to determine regional-scale element baselines. This report provides new data for 1,075 of the previously collected stream-sediment samples. The new analyses include a broader spectrum of elements and provide data that are more precise than the original analyses. All samples were analyzed for arsenic by hydride generation atomic absorption spectrometry, for gold, palladium, and platinum by inductively coupled plasma-mass spectrometry after lead button fire assay separation, and for a suite of 55 major, rare earth, and trace elements by inductively coupled plasma-atomic emission spectrometry and inductively coupled plasma-mass spectrometry after sodium peroxide sinter at 450 degrees Celsius.

  9. Geochemical evidence for the origin of late Quaternary loess in central Alaska

    USGS Publications Warehouse

    Muhs, D.R.; Budahn, J.R.

    2006-01-01

    Loess is extensive in central Alaska, but there are uncertainties about its source and the direction of paleo-winds that deposited it. Both northerly and southerly winds have been inferred. The most likely sources of loess are the Tanana River (south), the Nenana River (southeast), and the Yukon River (north). Late Quaternary loess in central Alaska has immobile trace-element compositions (Cr/Sc, Th/Ta, Th/ Sc, Th/U, Eu/Eu*, GdN/YbN) that indicate derivation mostly from the Tanana River. However, other ratios (As/Sb, Zr/Hf, LaN/YbN) and quantitative modeling indicate that the Yukon River was also a source. During the last glacial period, there may have been a longer residence time of the Siberian and Canadian high-pressure cells, along with a strengthened Aleutian low-pressure cell. This would have generated regional-scale northeasterly winds and explains derivation of loess from the Yukon River. However, superim-posed upon this synoptic-scale circulation, there may have been strong, southerly katabatic winds from expanded glaciers on the northern flank of the Alaska Range. These winds could have provided eolian silt from the Tanana River. Yukon River and Tanana River sediments are highly calcareous, whereas Fairbanks-area loess is not. This suggests that carbonate leaching in loess kept ahead of sedimentation and that late Quaternary loess in central Alaska was deposited relatively slowly. ?? 2006 NRC Canada.

  10. Geologic Map of the Nulato Quadrangle, West-Central Alaska

    USGS Publications Warehouse

    Patton, W.W.; Moll-Stalcup, E. J.

    2000-01-01

    Introduction The Nulato quadrangle encompasses approximately 17,000 km2 (6,500 mi2) of west-central Alaska within the Yukon River drainage basin. The quadrangle straddles two major geologic features-the Yukon-Koyukuk sedimentary basin, a huge triangle-shaped Cretaceous depression that stretches across western Alaska from the Brooks Range to the Yukon delta; and the Ruby geanticline,a broad uplift of pre-Cretaceous rocks that borders the Yukon-Koyukuk basin on the southeast. The Kaltag Fault crosses the quadrangle diagonally from northeast to southwest and dextrally offsets all major geologic features as much as 130 km.

  11. Deep-seated gravitational slope deformations near the Trans-Alaska Pipeline, east-central Alaska Range, Alaska, USA

    NASA Astrophysics Data System (ADS)

    Newman, S. D.; Clague, J. J.; Rabus, B.; Stead, D.

    2013-12-01

    Multiple, active, deep-seated gravitational slope deformations (DSGSD) are present near the Trans-Alaska Pipeline and Richardson Highway in the east-central Alaska Range, Alaska, USA. We documented spatial and temporal variations in rates of surface movement of the DSGSDs between 2003 and 2011 using RADARSAT-1 and RADARSAT-2 D-InSAR images. Deformation rates exceed 10 cm/month over very large areas (>1 km2) of many rock slopes. Recent climatic change and strong seismic shaking, especially during the 2002 M 7.9 Denali Fault earthquake, appear to have exacerbated slope deformation. We also mapped DSGSD geological and morphological characteristics using field- and GIS-based methods, and constructed a conceptual 2D distinct-element numerical model of one of the DSGSDs. Preliminary results indicate that large-scale buckling or kink-band slumping may be occurring. The DSGSDs are capable of generating long-runout landslides that might impact the Trans-Alaska Pipeline and Richardson Highway. They could also block tributary valleys, thereby impounding lakes that might drain suddenly. Wrapped 24-day RADARSAT-2 descending spotlight interferogram showing deformation north of Fels Glacier. The interferogram is partially transparent and is overlaid on a 2009 WorldView-1 panchromatic image. Acquisition interval: August 2 - August 26, 2011. UTM Zone 6N.

  12. Density of loons in central Alaska

    USGS Publications Warehouse

    Lanctot, Richard B.; Quang, Pham Xuan

    1992-01-01

    Loons breed across North America from the high arctic south to about 43 north latitude. (AOU 1983). Populations, particularly of Common Loons (Gavia immer) have recently declined in the continental U.S. and southern Canada (Sutcliff 1979, Titus and VanDruff 1981, McIntyre 1988). As a result, state and private natural resource organizations began more intensive monitoring of loon populations (in McIntyre 1986, Strong 1988). These surveys, however, are restricted to areas accessible by road, although recently aircraft were used for more remote areas (Lee and Arbuckle 1988, Strong 1990).

  13. Silurian gastropoda from southeastern and west-central Alaska

    USGS Publications Warehouse

    Rohr, D.M.; Blodgett, R.B.; Fryda, J.

    2008-01-01

    Additional Silurian (Ludlovian) gastropods are described from the Heceta Formation in the Alexander terrane on Prince of Wales Island, southeastern Alaska. Species include Spinicharybdis krizi n. sp., Spinicharybdis boucoti n. sp., Morania wagneri n. sp., Haplospira craigi n. sp., Australonema sp., Pachystrophia cf. gotlandica (Lindstro??m, 1884), and Medfrazyga gilmulli n. sp. An additional new Silurian species, Morania nixonforkensis n. sp., is described from the Nixon Fork subterrane of the Farewell terrane of west-central Alaska. The spine-bearing Spinicharybdis is placed into a new subfamily Spinicharybdiinae together with Hystricoceras Jahn, 1894. Joint occurrences of genera Beraunia, Coelocaulus, and Morania, as well as members of subfamily Spinicharybdiinae in the gastropod fauna from the Heceta Formation, support its close relationship with gastropod fauna of Bohemia. Additionally, the occurrence of the genus Medfrazyga suggests a faunal link between the Alexander and Farewell terranes of Alaska. Medfrazyga gilmulli n. sp. is the oldest known and the only early Paleozoic member of the family Palaeozygopleuridae. Copyright ?? 2008, The Paleontological Society.

  14. Hawkweed Control in Alaska

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Several hawkweed species from Europe have escaped ornamental planting and have colonized roadsides and grasslands in south central and southeast Alaska. These plants form near monotypic stands, reducing plant diversity and decreasing pasture productivity. A replicated greenhouse study was conducted ...

  15. Petrology of the Plutonic Rocks of west-central Alaska

    USGS Publications Warehouse

    Miller, Thomas P.

    1970-01-01

    A series of plutons in west-central Alaska defines the Hogatza plutonic belt which extends for about 200 miles in an east-west direction from the northeastern Seward Peninsula to the Koyukuk River. The plutonic rocks have an aggregate area of about 1,200 square miles and their composition, distribution, and possible petrogenesis are discussed for the first time in this report. Field, petrographic and chemical data supported by K/Ar age dating indicate the plutonic rocks are divisible into two suites differing in age, location, and composition. The western plutons are mid-Cretaceous (~100 m.y.) in age and consist of a heterogeneous assemblage of monzonite, syenite, quartz monzonite. Associated with these granitic rocks is a group of alkaline sub-silicic rocks that forma belt of intrusive complexes extending for a distance of at least 180 miles from west-central Alaska to the Bering Sea. The complex at Granite Mountain shows a rare example of zoning from an alkaline rim to a quartz-bearing core. The occurrence of a similar complex at Cape Dezhnev on the easternmost tip of Siberia suggests the alkaline province may extend into Siberia. The easternmost plutons are Late Cretaceous (180 m.y.) in age and composed primarily of granodiorite and quartz monzonite similar to calc-alkaline plutons found throughout the North America Cordillera. The plutons are epizonal and intrude deformed but unmetamorphosed Lower Cretaceous andesitic volcanics and volcanic graywacke which constitute the highly mobile Yukon-Koyukuk volcanogenic province of west-central Alaska. No older rocks have been found within the confines of this vast tract; the occurrence of a bounding ophiolite sequence has lead to the suggestion that the province was formed by large-scale rifting and is underlain by oceanic crust. The possibility of no juvenile sialic crust over much of the area suggests that the potassium-rich magma now represented by the alkaline rocks originated in the mantle. The distribution of the

  16. Reconstruction of recent climate change in Alaska from the Aurora Peak ice core, central Alaska

    NASA Astrophysics Data System (ADS)

    Tsushima, A.; Matoba, S.; Shiraiwa, T.; Okamoto, S.; Sasaki, H.; Solie, D. J.; Yoshikawa, K.

    2015-02-01

    A 180.17 m ice core was drilled at Aurora Peak in the central part of the Alaska Range, Alaska, in 2008 to allow reconstruction of centennial-scale climate change in the northern North Pacific. The 10 m depth temperature in the borehole was -2.2 °C, which corresponded to the annual mean air temperature at the drilling site. In this ice core, there were many melt-refreeze layers due to high temperature and/or strong insolation during summer seasons. We analyzed stable hydrogen isotopes (δD) and chemical species in the ice core. The ice core age was determined by annual counts of δD and seasonal cycles of Na+, and we used reference horizons of tritium peaks in 1963 and 1964, major volcanic eruptions of Mount Spurr in 1992 and Mount Katmai in 1912, and a large forest fire in 2004 as age controls. Here, we show that the chronology of the Aurora Peak ice core from 95.61 m to the top corresponds to the period from 1900 to the summer season of 2008, with a dating error of ± 3 years. We estimated that the mean accumulation rate from 1997 to 2007 (except for 2004) was 2.04 m w.eq. yr-1. Our results suggest that temporal variations in δD and annual accumulation rates are strongly related to shifts in the Pacific Decadal Oscillation index (PDOI). The remarkable increase in annual precipitation since the 1970s has likely been the result of enhanced storm activity associated with shifts in the PDOI during winter in the Gulf of Alaska.

  17. Reconstruction of recent climate change in Alaska from the Aurora Peak ice core, central Alaska

    NASA Astrophysics Data System (ADS)

    Tsushima, A.; Matoba, S.; Shiraiwa, T.; Okamoto, S.; Sasaki, H.; Solie, D. J.; Yoshikawa, K.

    2014-04-01

    A 180.17 m ice core was drilled at Aurora Peak in the central part of the Alaska Range, Alaska, in 2008 to allow reconstruction of centennial-scale climate change in the northern North Pacific. The 10 m-depth temperature in the borehole was -2.2 °C, which corresponded to annual mean air temperature at the drilling site. In this ice core, there were many melt-refrozen layers due to high temperature and/or strong insolation during summer seasons. We analyzed stable hydrogen isotopes (δD) and chemical species in the ice core. The ice core age was determined by annual counts of δD and seasonal cycles of Na+, and we used reference horizons of tritium peaks in 1963 and 1964, major volcanic eruptions of Mount Spurr in 1992 and Mount Katmai in 1912, and a large forest fire in 2004 as age controls. Here, we show that the chronology of the Aurora Peak ice core from 95.61 m w.eq. to the top corresponds to the period from 1900 to the summer season of 2008, with a dating error of ±3 years. We estimated that the mean accumulation rate from 1997 to 2007 (except for 2004) was 1.88 m w.eq per year. Our results suggest that temporal variation in δD and annual accumulation rates are strongly related to shifts in the Pacific Decadal Oscillation index (PDOI). The remarkable increase in annual precipitation since the 1970s has likely been the result of enhanced storm activity associated with shifts in the PDOI during winter in the Gulf of Alaska.

  18. South Central California Coastline and Channel Islands

    NASA Technical Reports Server (NTRS)

    1992-01-01

    This distant and very oblique image of the south Central California Coastline and Channel Islands (35.0N, 119.0W) offers a spectacular and scenic view of the southern west coast, the central San Joaquin Valley, the entire Sierra Nevada Range and across the southwest to the Rocky Mountains on the horizon.

  19. 78 FR 27863 - Fisheries of the Exclusive Economic Zone Off Alaska; Big Skate in the Central Regulatory Area of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-13

    ... Economic Zone Off Alaska; Big Skate in the Central Regulatory Area of the Gulf of Alaska AGENCY: National...: Temporary rule; closure. SUMMARY: NMFS is prohibiting retention of big skate in the Central Regulatory Area of the Gulf of Alaska (GOA). This action is necessary because the 2013 total allowable catch of...

  20. Deep-seated gravitational slope deformations near the Trans-Alaska Pipeline, east-central Alaska Range

    NASA Astrophysics Data System (ADS)

    Newman, Stephen Delmont, Jr.

    I investigated active deep-seated gravitational slope deformation (DSGSD) near the Trans-Alaska Pipeline and Richardson Highway in the east-central Alaska Range, Alaska, USA. I documented the presence, spatial extent, and rates of DSGSD using field-geology methods and optical, SAR, and D-InSAR remote-sensing images. I also documented and mapped many of the morphological, geological, and structural characteristics of slopes undergoing DSGSD, and constructed conceptual numerical models to better understand potential deformation mechanisms. Results confirm that many large DSGSD slopes in the study area are actively deforming. Deformation rates range from less than a millimetre per month to more than ten centimetres per month, and are spatially and temporally varient within each slope. Deforming slopes are characterized by differential movement of kilometre-scale rock blocks. Recent climatic changes and strong seismic shaking, especially during the recent 2002 Denali Fault earthquake, have exacerbated ongoing deformation. Study-area DSGSDs should be considered capable of generating long-runout rock avalanches that could directly sever the Trans-Alaska Pipeline and Richardson Highway, or that could dam up valleys and lead to the buildup and catastrophic failure of landslide-dammed lakes capable of impacting said infrastructure. Keywords: Deep-seated gravitational slope deformation; sackung; Trans-Alaska Pipeline; geomorphology; InSAR; Alaska Range.

  1. Flash Flooding Events in South Central Texas.

    DTIC Science & Technology

    1982-08-01

    I AD-ALI 977 AIR FORCE INST OF TECH WRIGHT-PATTERSON AFa OH F/G 4/2 FLASH FLOODING EVENTS IN SOUTH CENTRAL TEXAS. CU) N AU 82 T W UTLEY UNCLASSIFIED...COVERED Flash Flooding Events in South Central Texas THESIS/ESeAMAN S. PERFORMING ORG. REPORI NUMBER 7. AUTHOR(*) S. CONTRACT OR GRANT NUMBER(s) Tom...and to flash flooding events which occurred in 1981 they proved to be excellent predi’ctors. When compared to the 1981 National Weather Service

  2. Maps showing sedimentary basins, surface thermal maturity, and indications of petroleum in the Central Alaska Province

    USGS Publications Warehouse

    Troutman, Sandra M.; Stanley, Richard G.

    2003-01-01

    This publication includes two maps (at 1:2,500,000 scale) and a pamphlet that describe sedimentary basins, surface thermal maturity, and 95 reported occurrences of petroleum in natural seeps, wells, and rock outcrops in central Alaska. No commercial petroleum production has been obtained from central Alaska, in contrast to the prolific deposits of oil and gas that have been found and developed in northern Alaska and the Cook Inlet region. Nevertheless, confirmed indications of petroleum in central Alaska include (1) natural seeps of methane gas on the Yukon Delta; (2) occurrences of methane gas in wells in the Bethel, Kotzebue, Nenana, Northway, and Yukon Flats basins; (3) oil and methane gas in seeps and wells in Norton Sound; (4) small quantities of liquid and solid hydrocarbons associated with mercury ore in the Kuskokwim Mountains; (5) oil shale and numerous occurrences of bitumen in the Kandik area; and (6) tasmanite, a form of oil shale, in the uplands north of Yukon Flats.

  3. Reconnaissance for radioactive deposits in east-central Alaska, 1949

    USGS Publications Warehouse

    Wedow, Helmuth; White, M.G.

    1954-01-01

    In the summer of 1949, several mines and prospects in the Fairbanks and Livengood quadrangles, east-central Alaska, were examined for the possible presence of radioactive materials. Also tested were metamorphic and sedimentary rocks of pre-Cambrian and Paleozoic age crossed by the Elliott Highway, which extends from Fox, near Fairbanks, northwestward about 70 miles to the town of Livengood. Nuggets consisting chiefly of native bismuth and containing as much as 0.1 percent equivalent uranium had been found previously in a placer on Fish Creek several miles downstream from the reported bismuth-bearing lode on Melba Creek, but none of the lodes tested in 1949 exhibited radioactivity in excess of 0. 003 percent equivalent uranium. The greatest radioactivity found in the rocks along the Elliott Highway was in an iron-stained pre-Cambrian schist and in a carbonaceous(?) shale of Middle Devonian or Carboniferous age. Respective samples of these rocks contain 0. 003 and 0.004 percent equivalent uranium. A possible local bedrock source for the euxenite-polycrase mineral found in a placer concentrate containing about 0.04 percent equivalent uranium was sought in the watershed of Goodluck Creek, near Livengood. The bedrock source of this mineral could not be located and it is believed that the source could be outside of the Goodluck watershed because drainage changes during Quaternary time may well have introduced gravels from nearby areas.

  4. Floods of August 1967 in east-central Alaska

    USGS Publications Warehouse

    Childers, Joseph M.; Meckel, James P.; Anderson, Gary S.

    1972-01-01

    East-central Alaska had record floods near Fairbanks following extensive rains of August 8-20, 1967. Precipitation during this period totaled as much as 10 inches, which is close to the average annual precipitation for this area. The most extensive flooding occurred in the White Mountains northeast of Fairbanks and along the major streams draining those mountains. Some of the major streams flooded were the Salcha, Chena, Chatanika, Tolovana, and lower Tanana Rivers, and Birch Creek west of Circle. Peak discharges on some streams in the flood area were from two to four times the probable 50-year flood. The peak discharge of 74,400 cubic feet per second of the Chena River at Fairbanks, from 1,980 square miles of drainage area, was 2.6 times the 50-year flood. The rise of ground-water levels in the Tanana River flood plain to the land surface during the flood caused foundation failures and prevented drainage of subsurface structures. Above-normal ground-water levels existed until the middle of September. Total flood damage was estimated in excess of $85 million. Six lives were reported lost, and about 12,000 persons were evacuated during the flood. This report has been prepared to furnish hydrologic data for development planning. Included are discussions of antecedent streamflow, meteorology of the storm, descriptions of floods, flood damage, flood frequency, ground-water conditions, and stages and discharges of major streams for August 1967.

  5. Recurring middle Pleistocene outburst floods in east-central Alaska

    USGS Publications Warehouse

    Froese, D.G.; Smith, D.G.; Westgate, J.A.; Ager, T.A.; Preece, S.J.; Sandhu, A.; Enkin, R.J.; Weber, F.

    2003-01-01

    Recurring glacial outburst floods from the Yukon-Tanana Upland are inferred from sediments exposed along the Yukon River near the mouth of Charley River in east-central Alaska. Deposits range from imbricate gravel and granules indicating flow locally extending up the Yukon valley, to more distal sediments consisting of at least 10 couplets of planar sands, granules, and climbing ripples with up-valley paleocurrent indicators overlain by massive silt. An interglacial organic silt, occurring within the sequence, indicates at least two flood events are associated with an earlier glaciation, and at least three flood events are associated with a later glaciation which postdates the organic silt. A minimum age for the floods is provided by a glass fission track age of 560,000 ?? 80,000 yr on the GI tephra, which occurs 8 m above the flood beds. A maximum age of 780,000 yr for the floods is based on normal magnetic polarity of the sediments. These age constraints allow us to correlate the flood events to the early-middle Pleistocene. And further, the outburst floods indicate extensive glaciation of the Yukon-Tanana Upland during the early-middle Pleistocene, likely representing the most extensive Pleistocene glaciation of the area. ?? 2003 University of Washington. Published by Elsevier Inc. All rights reserved.

  6. 77 FR 76425 - Fisheries of the Exclusive Economic Zone Off Alaska; Reallocation of Pacific Cod in the Central...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-28

    ... Off Alaska; Reallocation of Pacific Cod in the Central Regulatory Area of the Gulf of Alaska... projected unused amount of Pacific cod from catcher vessels using trawl gear to vessels using pot gear and... catch of Pacific cod to be harvested. DATES: Effective December 26, 2012, through 2400 hrs, Alaska...

  7. Geologic map of the Big Delta B-2 quadrangle, east-central Alaska

    USGS Publications Warehouse

    Day, Warren C.; Aleinikoff, John N.; Roberts, Paul; Smith, Moira; Gamble, Bruce M.; Henning, Mitchell W.; Gough, Larry P.; Morath, Laurie C.

    2003-01-01

    New 1:63,360-scale geologic mapping of the Big Delta B-2 quadrangle provides important data on the structural setting and age of geologic units, as well as on the timing of gold mineralization plutonism within the Yukon-Tanana Upland of east-central Alaska. Gold exploration has remained active throughout the region in response to the discovery of the Pogo gold deposit, which lies within the northwestern part of the quadrangle near the south bank of the Goodpaster River. Geologic mapping and associated geochronological and geochemical studies by the U.S. Geological Survey (USGS) and the Alaska Department of Natural Resources, Division of Mining and Water Management, provide baseline data to help understand the regional geologic framework. Teck Cominco Limited geologists have provided the geologic mapping for the area that overlies the Pogo gold deposit as well as logistical support, which has lead to a much improved and informative product. The Yukon-Tanana Upland lies within the Tintina province in Alaska and consists of Paleozoic and possibly older(?) supracrustal rocks intruded by Paleozoic (Devonian to Mississippian) and Cretaceous plutons. The oldest rocks in the Big Delta B-2 quadrangle are Paleozoic gneisses of both plutonic and sedimentary origin. Paleozoic deformation, potentially associated with plutonism, was obscured by intense Mesozoic deformation and metamorphism. At least some of the rocks in the quadrangle underwent tectonism during the Middle Jurassic (about 188 Ma), and were subsequently deformed in an Early Cretaceous contractional event between about 130 and 116 Ma. New U-Pb SHRIMP data presented here on zircons from the Paleozoic biotite gneisses record inherited cores that range from 363 Ma to about 2,130 Ma and have rims of euhedral Early Cretaceous metamorphic overgrowths (116 +/- 4 Ma), interpreted to record recrystallization during Cretaceous west-northwest-directed thrusting and folding. U-Pb SHRIMP dating of monazite from a Paleozoic

  8. 77 FR 75966 - Control Date for Qualifying Landings History in the Central Gulf of Alaska Trawl Groundfish...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-26

    ... Landings History in the Central Gulf of Alaska Trawl Groundfish Fisheries AGENCY: National Marine Fisheries... permit history for an allocation-based management or catch share program in the Central Gulf of Alaska..., so that the full catch history for 2012 may be considered in any such future management actions....

  9. Map and digital database of sedimentary basins and indications of petroleum in the Central Alaska Province

    USGS Publications Warehouse

    Troutman, Sandra M.; Stanley, Richard G.

    2003-01-01

    This database and accompanying text depict historical and modern reported occurrences of petroleum both in wells and at the surface within the boundaries of the Central Alaska Province. These data were compiled from previously published and unpublished sources and were prepared for use in the 2002 U.S. Geological Survey petroleum assessment of Central Alaska, Yukon Flats region. Indications of petroleum are described as oil or gas shows in wells, oil or gas seeps, or outcrops of oil shale or oil-bearing rock and include confirmed and unconfirmed reports. The scale of the source map limits the spatial resolution (scale) of the database to 1:2,500,000 or smaller.

  10. Map showing extent of glaciation in the Eagle quadrangle, east-central Alaska

    USGS Publications Warehouse

    Weber, Florence R.; Wilson, Frederic H.

    2012-01-01

    This map covers the Eagle 1:250,000-scale quadrangle in the northeastern part of the Yukon-Tanana Upland in Alaska. It shows the extent of five major glacial advances, former glacial lakes, and present fragmented terrace deposits related to the advances. The Yukon-Tanana Upland is an area of about 116,550 km2 between the Yukon and Tanana Rivers in east-central Alaska that extends into the western part of the Yukon Territory of Canada. Traditionally, the Yukon-Tanana Upland was thought to be a part of unglaciated central Alaska, however, a rather long history of localized alpine glaciation during Pleistocene and possibly Tertiary time can be shown. Deposits of five of the glacial episodes can be found in the Eagle quadrangle. This report is an outcome of studies conducted in conjunction with bedrock mapping intended for mineral resource assessment.

  11. Vegetation and paleoclimate of the last interglacial period, central Alaska

    USGS Publications Warehouse

    Muhs, D.R.; Ager, T.A.; Beget, J.E.

    2001-01-01

    The last interglacial period is thought to be the last time global climate was significantly warmer than present. New stratigraphic studies at Eva Creek, near Fairbanks, Alaska indicate a complex last interglacial record wherein periods of loess deposition alternated with periods of soil formation. The Eva Forest Bed appears to have formed about the time of or after deposition of the Old Crow tephra (dated to ??? 160 to ??? 120 ka), and is therefore correlated with the last interglacial period. Pollen, macrofossils, and soils from the Eva Forest Bed indicate that boreal forest was the dominant vegetation and precipitation may have been greater than present around Fairbanks during the peak of the last interglacial period. A new compilation of last interglacial localities indicates that boreal forest was extensive over interior Alaska and Yukon Territory. Boreal forest also extended beyond its present range onto the Seward and Baldwin Peninsulas, and probably migrated to higher elevations, now occupied by tundra, in the interior. Comparison of last interglacial pollen and macrofossil data with atmospheric general circulation model results shows both agreement and disagreement. Model results of warmer-than-present summers are in agreement with fossil data. However, numerous localities with boreal forest records are in conflict with model reconstructions of an extensive cool steppe in interior Alaska and much of Yukon Territory during the last interglacial. ?? 2000 Elsevier Science Ltd.

  12. Break-up characteristics of the Chena River watershed, central Alaska

    NASA Technical Reports Server (NTRS)

    Carlson, R. F. (Principal Investigator); Wendler, G.; Kane, D. L.

    1973-01-01

    The author has identified the following significant results. The snow melt for a small watershed (5130 sq km) in Central Alaska was successfully monitored with ERTS-1 imagery. Aerial photography was used as supporting data for periods without satellite coverage. Comparison both with actual measurements and with a computer model showed good agreement.

  13. Radioactivity at the Copper Creek copper lode prospect, Eagle district, east-central Alaska

    USGS Publications Warehouse

    Wedow, Helmuth; Tolbert, Gene Edward

    1952-01-01

    Investigation of radioactivity anomalies at the Copper Creek copper lode prospect, Eagle district, east-central Alaska, during 1949 disclosed that the radioactivity is associated with copper mineralization in highly metamorphosed sedimentary rocks. These rocks are a roof pendant in the Mesozoic "Charley River" batholith. The radioactivity is probably all due to uranium associated with bornite and malachite.

  14. Geologic setting and chemical characteristics of hot springs in central and western Alaska

    USGS Publications Warehouse

    Miller, Thomas P.; Barnes, Ivan; Pattan, William Wallace

    1973-01-01

    The geologic and chemical data are too preliminary to make an estimate of the potential of the hot springs as a geothermal resource. The data suggest, however, that most of the hot springs of central and western Alaska have relatively low subsurface temperatures and limited reservoir capacities in comparison with geothermal areas presently being utilized for electrical power generation.

  15. Geological Character and Mineral Resources of South Central Lake Erie.

    DTIC Science & Technology

    1982-10-01

    AD-A123 085 GEOLOGICAL CHARACTERAND MINERAL RESOURCES OF SOUTH 1/ CENTRAL LAKE ERIE(U) COASTAL ENGINEERING RESEARCH CENT ER FORT E LVOIR VA S d...CHART NATMOAL BUREAU Of STANDARDS-1963-A 1.1 lilt. AR MR 82-9 Geological Character and Mineral Resources of South Central Lake Erie by S. Jeff ress...GEOLOGICAL CHARACTER AND MINERAL RESOURCES Miscellaneous Report OF SOUTH CENTRAL LAKE ERIE 6. PERFORMING ORG. REPORT NUMBER 7. AUTHORI’.) S. CONTRACT

  16. Tertiary tectonics of the Border Ranges Fault system, north-central Chugach Mountains, Alaska: Sedimentation, deformation and uplift along the inboard edge of a subduction complex

    SciTech Connect

    Little, T.A.

    1988-01-01

    In south-central Alaska the Border Ranges Fault system (BRFS) separates lower Paleogene rocks of a forearc basin sequence from a Cretaceous subduction complex. In a north-central part of the Chugach Mountains the upper Paleocene-lower Eocene Chickaloon Formation was deposited along the seaward margin of the forearc basin as an alluvial fan complex. A field study combining geologic mapping of a {approximately}200 km{sup 2} region, stratigraphic studies, K-Ar and fission-track geochronology, metamorphic petrology, and detailed structural analysis of deformed rocks on both sides of the BRFS has been used to reconstruct the Tertiary history of displacements and uplift events along the inboard edge of Alaska's subduction-accretion complex.

  17. CASA Central and South America GPS geodesy

    NASA Astrophysics Data System (ADS)

    Kellogg, James; Dixon, Timothy; Neilan, Ruth

    In January 1988, scientists from over 25 organizations in 13 countries and territories cooperated in the largest Global Positioning System (GPS) campaign in the world to date (Table 1) [Neilan et al., 1988]. From January 18 to February 5, 1988, 43 GPS receivers collected about 590 station-days of data in American Samoa, Australia, Canada, Colombia, Costa Rica, Ecuador, New Zealand, Norway, Panama, Sweden, United States, West Germany, and Venezuela. The experiment was entitled CASA UNO, an acronym for Central and South America—and “uno” is Spanish for “one,” designating first-epoch measurements. The CASA UNO experiment was the first civilian effort at implementing an extended GPS satellite-tracking network and established the first major GPS network in the northern Andean margin and the western Caribbean.

  18. Mantle Structure Beneath Central South America

    NASA Astrophysics Data System (ADS)

    Vandecar, J. C.; Silver, P. G.; James, D. E.; Assumpcao, M.; Schimmel, M.; Zandt, G.

    2003-12-01

    Making use of 60 digital broadband seismic stations that have operated across central South America in recent years, we have undertaken an inversion for the upper- and uppermost lower-mantle P- and S-wave velocity structures beneath the region. We have combined data from four portable PASSCAL-type experiments as well as the 3 GTSN permanent stations (LPAZ, BDFB and CPUP) and 1 Geoscope station (SPB) located in the region. The portable data were deployed at various times between 1992 and 1999 and include: 28 sites from the Brazilian Lithosphere Seismic Project (BLSP: Carnegie Institution of Washington and Universidade de Sao Paulo), 16 sites from the Broadband ANdean JOint experiment (BANJO: Carnegie Institution of Washington and University of Arizona), 8 sites from the Seismic Exploration of the Deep Altiplano project (SEDA: Lawrence Livermore National Laboratory) and 4 sites from the University of Brasilia. The P- and S-wave relative delay times are independently obtained via a multi-channel cross correlation of band-passed waveforms for each teleseismic event. These data are then inverted using an iterative, robust, non-linear scheme which parameterizes the 3-D velocity variations as splines under tension constrained at over 120,000 nodes across South America between latitudes of 15 and 30 degrees South. Amongst other features, we robustly image the high-velocity subducting Nazca plate penetrating into the lower mantle and the high-velocity root of the ~3.2 Gyr old Sao Francisco Craton extending to depths of 200-300 km. We will discuss the consistency between our tomographic models and predictions of dynamic mantle models based on plate tectonic reconstructions of subduction.

  19. 29. INTERIOR VIEW OF FERRY MOUSE, SOUTH CENTRAL BUILDING, FIRST ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    29. INTERIOR VIEW OF FERRY MOUSE, SOUTH CENTRAL BUILDING, FIRST LEVEL, LOOKING WEST, FERRYMEN'S QUARTERS - Central Railroad of New Jersey, Jersey City Ferry Terminal, Johnson Avenue at Hudson River, Jersey City, Hudson County, NJ

  20. Alaska

    SciTech Connect

    Jones, B.C.; Sears, D.W.

    1981-10-01

    Twenty-five exploratory wells were drilled in Alaska in 1980. Five oil or gas discovery wells were drilled on the North Slope. One hundred and seventeen development and service wells were drilled and completed, primarily in the Prudhoe Bay and Kuparuk River fields on the North Slope. Geologic-geophysical field activity consisted of 115.74 crew months, an increase of almost 50% compared to 1979. These increases affected most of the major basins of the state as industry stepped up preparations for future lease sales. Federal acreage under lease increased slightly, while state lease acreage showed a slight decline. The year's oil production showed a increase of 16%, while gas production was down slightly. The federal land freeze in Alaska showed signs of thawing, as the US Department of Interior asked industry to identify areas of interest onshore for possible future leasing. National Petroleum Reserve in Alaska was opened to private exploration, and petroleum potential of the Arctic Wildlife Refuge will be studied. One outer continental shelf lease sale was held in the eastern Gulf of Alaska, and a series of state and federal lease sales were announced for the next 5 years. 5 figures, 5 tables.

  1. An Ongoing Large Slow Slip Event in the Southern Central Alaska Subduction Zone

    NASA Astrophysics Data System (ADS)

    Freymueller, J. T.; Fu, Y.

    2012-12-01

    We analyze time series of GPS measurement in southern central Alaska, and identify an ongoing long-term slow slip event (SSE) occurring since the end of 2008 around Anchorage Alaska area, starting 7-8 years later after the end of the previous 1998-2001 SSE. The slow slip event is counter-acting the background linear trend of plate convergence between Pacific and North America plates. Significant velocity changes are very obvious in north and height directions, and detectable in the east. Detailed analysis of continuous GPS time series indicates this slow slip event started at ~2008.96, and is still continuing since then. This slow slip event appears to have a very slow rise time, unlike the 1998-2001 event. Through mid-2012, GPS time series during this long-term slow slip can be well fitted with a linear term plus an exponential (or logarithmic) term. The velocity changes are located around and north of Anchorage, which indicates that the SSE is occurring at the downdip of the locked seismogenic zone of the southern central Alaska subduction zone, like the 1998-2001 event. We will use both continuous and campaign (including the campaign measurements of later summer of 2012) GPS measurements to better constrain the location and amplitude of the ongoing SSE in southern central Alaska, and compare with the 1964 earthquake rupture zone to discuss the relationship between locked zone, SSE zone and free slip zone in terms of their contributions to large earthquake in Alaska subduction zone.

  2. Alaska

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Though it's not quite spring, waters in the Gulf of Alaska (right) appear to be blooming with plant life in this true-color MODIS image from March 4, 2002. East of the Alaska Peninsula (bottom center), blue-green swirls surround Kodiak Island. These colors are the result of light reflecting off chlorophyll and other pigments in tiny marine plants called phytoplankton. The bloom extends southward and clear dividing line can be seen west to east, where the bloom disappears over the deeper waters of the Aleutian Trench. North in Cook Inlet, large amounts of red clay sediment are turning the water brown. To the east, more colorful swirls stretch out from Prince William Sound, and may be a mixture of clay sediment from the Copper River and phytoplankton. Arcing across the top left of the image, the snow-covered Brooks Range towers over Alaska's North Slope. Frozen rivers trace white ribbons across the winter landscape. The mighty Yukon River traverses the entire state, beginning at the right edge of the image (a little way down from the top) running all the way over to the Bering Sea, still locked in ice. In the high-resolution image, the circular, snow-filled calderas of two volcanoes are apparent along the Alaska Peninsula. In Bristol Bay (to the west of the Peninsula) and in a couple of the semi-clear areas in the Bering Sea, it appears that there may be an ice algae bloom along the sharp ice edge (see high resolution image for better details). Ground-based observations from the area have revealed that an under-ice bloom often starts as early as February in this region and then seeds the more typical spring bloom later in the season.

  3. Origin of narrow terranes and adjacent major terranes occurring along the denali fault in the eastern and central alaska range, alaska

    USGS Publications Warehouse

    Nokleberg, W.J.; Richter, D.H.

    2007-01-01

    Several narrow terranes occur along the Denali fault in the Eastern and Central Alaska Range in Southern Alaska. These terranes are the Aurora Peak, Cottonwood Creek, Maclaren, Pingston, and Windy terranes, and a terrane of ultramafic and associated rocks. Exterior to the narrow terranes to the south is the majorWrangellia island arc composite terrane, and to the north is the major Yukon Tanana metamorphosed continental margin terrane. Overlying mainly the northern margin of the Wrangellia composite terrane are the Kahiltna overlap assemblage to the west, and the Gravina- Nutzotin-Gambier volcanic-plutonic- sedimentary belt to the east and southeast. The various narrow terranes are interpreted as the result of translation of fragments of larger terranes during two major tectonic events: (1) Late Jurassic to mid-Cretaceous accretion of the Wrangellia island arc composite terrane (or superterrane composed of the Wrangellia, Peninsular, and Alexander terranes) and associated subduction zone complexes; and (2) starting in about the Late Cretaceous, dextral transport of the Wrangellia composite terrane along the Denali fault. These two major tectonic events caused: (1) entrapment of a lens of oceanic lithosphere along the suture belt between the Wrangellia composite terrane and the North American Craton Margin and outboard accreted terranes to form the ultramafic and mafic part of the terrane of ultramafic and associated rocks, (2) subsequent dextral translation along the Denali fault of the terrane of ultramafic and associated rocks, (3) dextral translation along the Denali fault of the Aurora Peak, Cottonwood Creek, and Maclaren and continental margin arc terranes from part of the Coast plutonic-metamorphic complex (Coast-North Cascade plutonic belt) in the southwest Yukon Territory or Southeastern Alaska, (4) dextral translation along the Denali fault of the Pingston passive continental margin from a locus along the North American Continental Margin, and (5

  4. 150,000 years of loess accumulation in central Alaska

    NASA Astrophysics Data System (ADS)

    Jensen, Britta J. L.; Evans, Michael E.; Froese, Duane G.; Kravchinsky, Vadim A.

    2016-03-01

    The Halfway House site in interior Alaska is arguably the most studied loess deposit in northwestern North America. The site contains a complex paleomagnetic and paleoenvironmental record, but has lacked the robust chronologic control that would allow its full potential to be exploited. Detailed reexamination of stratigraphy, paleomagnetics and tephrostratigraphy reveals a relatively complete marine isotope stage (MIS) 6 to Holocene record constrained by the Old Crow (124 ± 10 ka), VT (106 ± 10 ka), Sheep Creek-Klondike (ca. 80 ka), Dominion Creek (77 ± 8 ka) and Dawson (ca. 30.2 cal ka BP) tephras. We show two well-developed paleosols formed during Marine Isotope Stages (MIS) 5e and 5a, while MIS 5c and 5b are either poorly represented or absent. The new tephrostratigraphy presented here is the most complete one to date for the late Pleistocene and indicates MIS 5 sediments are more common than previously recognized. A magnetic excursion within the sediments is identified as the post-Blake excursion (94.1 ± 7.8 ka), providing independent age control and adding to the increasing body of evidence that Alaskan loess is a detailed recorder of variations of the Earth's magnetic field over time. A high-resolution magnetic susceptibility profile placed into this new chronostratigraphic framework supports the hypothesis that wind-intensity is the main variable controlling fluctuations in susceptibility. Correlation of the susceptibility record to global marine δ18O records is complicated by highly variable accumulation rates. We find the lowest rates of accumulation during peak warm and cold stages, while abrupt increases are associated with periods of transition between marine isotope (sub)stages. Building on previous accumulation models for Alaska, surface roughness is likely a leading variable controlling loess accumulation rates during transitions and peak cold periods, but the negligible accumulation during MIS 5e and 5a suggests that loess production was

  5. Structural architecture of the central Brooks Range foothills, Alaska

    USGS Publications Warehouse

    Moore, Thomas E.; Potter, Christopher J.; O'Sullivan, Paul B.

    2002-01-01

    Five structural levels underlie the Brooks Range foothills, from lowest to highest: (1) autochthon, at a depth of ~9 km; (2) Endicott Mountains allochthon (EMA), thickest under the northern Brooks Range (>15 km) and wedging out northward above the autochthon; (3) higher allochthons (HA), with a composite thickness of 1.5+ km, wedging out northward at or beyond the termination of EMA; (4) Aptian-Albian Fortress Mountain Formation (FM), deposited unconformably on deformed EMA and HA and thickening northward into a >7-km-thick succession of deformed turbidites (Torok Formation); (5) gently folded Albian-Cenomanian deltaic deposits (Nanushuk Group). The dominant faulting pattern in levels 2-3 is thin-skinned thrusting and thrust-related folds formed before deposition of Cretaceous strata. These structures are cut by younger steeply south-dipping reverse faults that truncate and juxtapose structural levels 1-4 and expose progressively deeper structural levels to the south. Structural levels 4-5 are juxtaposed along a north-dipping zone of south-vergent folds and thrusts. Stratigraphic and fission-track age data suggest a kinematic model wherein the foothills belt was formed first, by thrusting of HA and EMA as deformational wedges onto the regionally south-dipping authochon at 140-120Ma. After deposition of FM and Torok during mid-Cretaceous hinterland extension and uplift, a second episode of contractional deformation at 60 Ma shortened the older allochthonous deformational wedges (EMA, HA) and overlying strata on north-vergent reverse faults. To the north, where the allochthons wedge out, shortening caused duplexing in the Torok and development of a triangle zone south of the Tuktu escarpment.

  6. Geology of the central Copper River region, Alaska

    USGS Publications Warehouse

    Mendenhall, Walter C.

    1905-01-01

    It is an interesting evidence of the prompt responsiveness of our governmental organization to popular needs that the year 1898, which saw the first rush of argonauts to Alaska as a result of the discovery of the Klondike in 1986, saw also several well-equipped Federal parties at work in the Territory, mapping its great waterways and mountain ranges, investigating the feasible means of transportation within it, laying out routes for future lines of communication, and studying the mineral resources and the plant and animal life. It is true that before that year, in which the general attention of the world was fixed upon our heretofore lightly regarded northern province, fur traders, adventurous travelers, and hardy prospectors had made little-heralded journeys through the interior, and that one or another of the governmental departments had had representatives on special errands within its borders, but the amount of private and public energy expended there in 1898 probably exceeded that of any ten previous years.

  7. Logs and Geologic Data from a Paleoseismic Investigation of the Susitna Glacier fault, Central Alaska Range, Alaska

    USGS Publications Warehouse

    Personius, Stephen F.; Crone, Anthony J.; Burns, Patricia A.C.; Beget, James E.; Seitz, Gordon G.; Bemis, Sean P.

    2010-01-01

    This report contains field and laboratory data from a paleoseismic study of the Susitna Glacier fault, Alaska. The initial M 7.2 subevent of the November 3, 2002, M 7.9 Denali fault earthquake sequence produced a 48-km-long set of complex fault scarps, folds, and aligned landslides on the previously unknown, north-dipping Susitna Glacier thrust fault along the southern margin of the Alaska Range in central Alaska. Most of the 2002 folds and fault scarps are 1-3 m high, implying dip-slip thrust offsets (assuming a near-surface fault dip of approximately 20 degrees)of 3-5 m. Locally, some of the 2002 ruptures were superimposed on preexisting scarps that have as much as 5-10 m of vertical separation and are evidence of previous surface-rupturing earthquakes on the Susitna Glacier fault. In 2003-2005, we focused follow-up studies on several of the large scarps at the 'Wet fan' site in the central part of the 2002 rupture to determine the pre-2002 history of large surface-rupturing earthquakes on the fault. We chose this site for several reasons: (1) the presence of pre-2002 thrust- and normal-fault scarps on a gently sloping, post-glacial alluvial fan; (2) nearby natural exposures of underlying fan sediments revealed fine-grained fluvial silts with peat layers and volcanic ash beds useful for chronological control; and (3) a lack of permafrost to a depth of more than 1 m. Our studies included detailed mapping, fault-scarp profiling, and logging of three hand-excavated trenches. We were forced to restrict our excavations to 1- to 2-m-high splay faults and folds because the primary 2002 ruptures mostly were superimposed on such large scarps that it was impossible to hand dig through the hanging wall to expose the fault plane. Additional complications are the pervasive effects of cryogenic processes (mainly solifluction) that can mask or mimic tectonic deformation. The purpose of this report is to present photomosaics, trench logs, scarp profiles, and fault slip

  8. Holocene loess and paleosols in central Alaska: A proxy record of Holocene climate change

    SciTech Connect

    Bigelow, N.H.; Beget, J.E.

    1992-03-01

    Episodic Holocene loess deposition and soil formation in the sediments of the Nenana valley of Central Alaska may reflect Holocene climate change. Periods of loess deposition seem to correlate with times of alpine glacier activity, while paleosols correspond to times of glacial retreat These variations may reflect changes in solar activity Stuiver and Braziunas, 1989. Other mechanisms, such as orbitally forced changes in seasonality, volcanism, and atmospheric C02 variability may also have affected Holocene climates and loess deposition.

  9. Limits to northward drift of the Paleocene Cantwell Formation, central Alaska.

    USGS Publications Warehouse

    Hillhouse, J.W.; Gromme, C.S.

    1982-01-01

    Volcanic rocks of the Paleocene Cantwell Formation in central Alaska apparently originated at a paleolatitude of 83oN (alpha 95 = 9.7o), as indicated by paleomagnetic results. When compared with the Paleocene pole for the North American craton, the 95% confidence limits of the results suggest that terranes N of the Denali fault have moved no more than 550km northward relative to the North American craton since Paleocene time.-Authors

  10. Tectonics and surface processes interactions in exhumation history of South Alaska: insights from the thermochronological record

    NASA Astrophysics Data System (ADS)

    Valla, Pierre G.; Champagnac, Jean-Daniel; Shuster, David L.; Herman, Frederic; Giuditta Fellin, Maria

    2014-05-01

    The southern Alaska range presents an ideal setting to study complex interactions between tectonics, climate and surface processes in landscape evolution. It exhibits active tectonics with the ongoing of subduction/collision between Pacific and North America, and major active seismogenic reverse and strike-slip faults. The alpine landscape, rugged topography and the important present-day ice-coverage reveal a strong glacial imprint associated with high erosion and sediment transport rates. Therefore, the relative importance of glacial erosion and tectonics for the observed late-exhumation history appears to be quite complex to decipher. This problem partly arises from the fact that most studies have been focused on the southern coast of Alaska where both glacial erosion and tectonic processes are both very active and act together in driving high exhumation rates. Here, we first perform a formal inversion of an extensive bedrock thermochronological dataset collected in southern Alaska over the last decades to quantify the large-scale 20-Myr exhumation history. Our results confirm high exhumation rates in the St Elias "syntaxis" and frontal fold and thrust belts for the last 0-2 Myr, where major ice fields and high precipitation rates likely promoted high erosion rates. It also highlights localized exhumation in the last 4-6 Myr along major tectonic features such like the Fairweather and Border Ranges faults. Large-scale inverse modeling therefore suggests that the late-stage exhumation history of South Alaska has mainly been driven by tectonic processes; the impact of late Cenozoic glaciations impact being less visible there than in less active mountain ranges such as the European Alps, British Columbia or Patagonia. To overcome this potential bias in resolving the glacial impact on erosion history, we studied to the Granite Range (Wrangell-St Elias National Park, Alaska), an area presenting a strong glacial imprint but minor tectonic activity with only localized

  11. Geochronology, geochemistry, and tectonic environment of porphyry mineralization in the central Alaska Peninsula

    USGS Publications Warehouse

    Wilson, Frederic H.; Cox, Dennis P.

    1983-01-01

    Porphyry type sulfide systems on the central Alaska Peninsula occupy a transition zone between the Aleutian island magmatic arc and the continental magmatic arc of southern Alaska. Mineralization occurs associated with early and late Tertiary magmatic centers emplaced through a thick section of Mesozoic continental margin clastic sedimentary rocks. The systems are of the molybdenum-rich as opposed to gold-rich type and have anomalous tungsten, bismuth, and tin, attributes of continental-margin deposits, yet gravity data suggest that at least part of the study area is underlain by oceanic or transitional crust. Potassium-argon age determinations indicate a variable time span of up to 2 million years between emplacement and mineralization in a sulfide system with mineralization usually followed by postmineral intrusive events. Finally, mineralization in the study area occurred at many times during the time span of igneous activity and should be an expected stage in the history of a subduction related magmatic center.

  12. 88. 451 MADISON AVENUE, LIBRARY, SOUTH WALL, WEST CENTRAL SECTION ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    88. 451 MADISON AVENUE, LIBRARY, SOUTH WALL, WEST CENTRAL SECTION SHOWING WINDOW AND RADIATOR (Pair with NY-5635-89) - Villard Houses, 451-457 Madison Avenue & 24 East Fifty-first Street, New York County, NY

  13. FY10 RARE Final Report to Region 10: The functional Assessment of Alaska Peatlands in Cook Inlet Basin - report

    EPA Science Inventory

    Peatlands in south central Alaska form the predominant wetland class in the lowlands that encompass Cook Inlet. These peatlands are also in areas of increasing human development in Alaska. Currently Alaska peatlands are extensive and largely pristine. This study focused onobtaini...

  14. Lithostratigraphic, conodont, and other faunal links between lower Paleozoic strata in northern and central Alaska and northeastern Russia

    USGS Publications Warehouse

    Dumoulin, Julie A.; Harris, Anita G.; Gagiev, Mussa; Bradley, Dwight C.; Repetski, John E.

    2002-01-01

    Lower Paleozoic platform carbonate strata in northern Alaska (parts of the Arctic Alaska, York, and Seward terranes; herein called the North Alaska carbonate platform) and central Alaska (Farewell terrane) share distinctive lithologic and faunal features, and may have formed on a single continental fragment situated between Siberia and Laurentia. Sedimentary successions in northern and central Alaska overlie Late Proterozoic metamorphosed basement; contain Late Proterozoic ooid-rich dolostones, Middle Cambrian outer shelf deposits, and Ordovician, Silurian, and Devonian shallow-water platform facies, and include fossils of both Siberian and Laurentian biotic provinces. The presence in the Alaskan terranes of Siberian forms not seen in wellstudied cratonal margin sequences of western Laurentia implies that the Alaskan rocks were not attached to Laurentia during the early Paleozoic.The Siberian cratonal succession includes Archean basement, Ordovician shallow-water siliciclastic rocks, and Upper Silurian–Devonian evaporites, none of which have counterparts in the Alaskan successions, and contains only a few of the Laurentian conodonts that occur in Alaska. Thus we conclude that the lower Paleozoic platform successions of northern and central Alaska were not part of the Siberian craton during their deposition, but may have formed on a crustal fragment rifted away from Siberia during the Late Proterozoic. The Alaskan strata have more similarities to coeval rocks in some peri-Siberian terranes of northeastern Russia (Kotelny, Chukotka, and Omulevka). Lithologic ties between northern Alaska, the Farewell terrane, and the peri-Siberian terranes diminish after the Middle Devonian, but Siberian afµnities in northern and central Alaskan biotas persist into the late Paleozoic.

  15. Sedimentology and stratigraphy of the Kanayut Conglomerate, central and western Brooks Range, Alaska; report of 1981 field season

    USGS Publications Warehouse

    Nilsen, T.H.; Moore, T.E.

    1982-01-01

    The Upper Devonian and Lower Mississippian(?) Kanayut Conglomerate forms a major stratigraphic unit along the crest of the Brooks Range of northern Alaska. It crops out for an east-west distance of about 900 km and a north-south distance of about 65 km. The Kanayut is wholly allochthonous and has probably been transported northward on a series of thrust plates. The Kanayut is as thick as 2,600 m in the east-central Brooks Range. It thins and fines to the south and west. The Kanayut forms the middle part of the allochthonous sequence of the Endicott Group, an Upper Devonian and Mississippian clastic sequence underlain by platform limestones of the Baird Group and overlain by platform limestone, carbonaceous shale, and black chert of the Lisburne Group. The Kanayut overlies the marine Upper Devonian Noatak Sandstone or, where it is missing, the marine Upper Devonian Hunt Fork Shale. It is overlain by the marine Mississippian Kayak Shale. The Kanayut Conglomerate forms the fluvial part of a large, coarse-grained delta that prograded to the southwest in Late Devonian time and retreated in Early Mississippian time. Four sections of the Kanayut Conglomerate in the central Brooks Range and five in the western Brooks Range were measured in 1981. The sections from the western Brooks Range document the presence of fluvial cycles in the Kanayut as far west as the shores of the Chukchi Sea. The Kanayut in this area is generally finer grained than it is in the central and eastern Brooks Range, having a maximum clast size of 3 cm. It is probably about 300 m thick. The upper and lower contacts of the Kanayut are gradational. The lower Kanayut contains calcareous, marine-influenced sandstone within channel deposits, and the upper Kanayut contains probable marine interdistributary-bay shale sequences. The members of the Kanayut Conglomerate cannot be differentiated in this region. In the central Brooks Range, sections of the Kanayut Conglomerate at Siavlat Mountain and Kakivilak

  16. Ophiolitic terranes of northern and central Alaska and their correlatives in Canada and northeastern Russia

    SciTech Connect

    Patton, W.W. Jr. )

    1993-04-01

    All of the major ophiolitic terranes (Angayucham, Tozitna, Innoko, Seventymile, and Goodnews terranes) in the northern and central Alaska belong to the Tethyan-type' of Moores (1982) and were obducted onto Paleozoic and Proterozoic continental and continental margin terranes in Mesozoic time. Tethyan-type' ophiolitic assemblages also occur in the Slide Mountain terrane in the Canadian Cordillera and extend from western Alaska into northeastern Russia. Although investigators have suggested widely different ages from their times of abduction onto the continent, these ophiolitic terranes display some remarkably similar features: (1) they consist of a stack of imbricated thrust slices dominated by ocean floor sediments, basalt, and high-level gabbro of late Paleozoic and Triassic age; (2) their mafic-ultramafic complexes generally are confined to the uppermost thrust sheets; (3) they lack the large tectonic melanges zones and younger accretionary flysch deposits associated with the ophiolitic terranes of southern Alaska and the Koryak region of northeastern Russia; (4) blueschist mineral assemblages occur in the lower part of these ophiolite terranes and (or) in the underlying continental terranes; and (5) they are bordered on their outboard' side by Mesozoic intraoceanic volcanic arc terranes. Recent geochemical and geologic studies of the mafic-ultramafic complexes in the Anagayucham and Tozitna terranes strongly suggest they were generated in a supra-subduction zone (SSZ) and that they are directly overlain by volcanic rocks of the Koyukuk terrane.

  17. 77 FR 39440 - Fisheries of the Exclusive Economic Zone Off Alaska; Pacific Ocean Perch in the Central Aleutian...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-03

    ... Economic Zone Off Alaska; Pacific Ocean Perch in the Central Aleutian District of the Bering Sea and... directed fishing for Pacific ocean perch in the Central Aleutian District of the Bering Sea and Aleutian... action is necessary to prevent exceeding the 2012 allocation of Pacific ocean perch in this...

  18. Neogene transpressional foreland basin development on the north side of the central alaska range, usibelli group and nenana gravel, tanana basin

    USGS Publications Warehouse

    Ridgway, K.D.; Thoms, E.E.; Layer, P.W.; Lesh, M.E.; White, J.M.; Smith, S.V.

    2007-01-01

    Neogene strata of the Tanana basin provide a long-term record of a northwardpropagating, transpressional foreland-basin system related to regional shortening of the central Alaska Range and strike-slip displacement on the Denali fault system. These strata are ???2 km thick and have been deformed and exhumed in thrust faults that form the foothills on the north side of the Alaska Range. The lower part of the sedimentary package, the Usibelli Group, consists of 800 m of mainly Miocene strata that were deposited in fluvial, lacustrine, and peat bog environments of the foredeep depozone of the foreland-basin system. Compositional data from conglomerate and sandstone, as well as recycled Upper Cretaceous palynomorphs, indicate that the Miocene foreland-basin system was supplied increasing amounts of sediment from lithologies currently exposed in thrust sheets located south of the basin. The upper part of the sedimentary package, the Nenana Gravel, consists of 1200 m of mainly Pliocene strata that were deposited in alluvial-fan and braidplain environments in the wedge-top depozone of the foreland-basin system. Compositional data from conglomerate and sandstone, as well as 40Ar/39Ar dating of detrital feldspars in sandstone and from granitic clasts in conglomerate, indicate that lithologies exposed in the central Alaska Range provided most of the detritus to the Pliocene foreland-basin system. 40Ar/39Ar dates from detrital feldspar grains also show that two main suites of plutons contributed sediment to the Nenana Gravel. Detrital feldspars with an average age of 56 Ma are interpreted to have been derived from the McKinley sequence of plutons located south of the Denali fault. Detrital feldspars with an average age of 34 Ma are interpreted to have been derived from plutons located north of the Denali fault. Plutons located south of the Denali fault provided detritus for the lower part of the Nenana Gravel, whereas plutons located north of the Denali fault began to

  19. Middle Cambrian fossils from the Doonerak anticlinorium, central Brooks Range, Alaska.

    USGS Publications Warehouse

    Dutro, J.T.; Palmer, A.R.; Repetski, J.E.; Brosge, W.P.

    1984-01-01

    Middle Cambrian fossils collected near Wolf Creek in the Wiseman quadrangle, northern Alaska, include trilobites and paraconodonts. Trilobites date the strata as early Middle Cambrian, correlative with the Amgan Stage of Siberia. The assemblage includes: Kootenia cf. K. anabarensis Lermontova, cf. 'Parehmania' lata Chernysheva and Pagetia sp. Specimens of the paracondont genus Westergaardodina, from the same sample as the megafossils, record the earliest known occurrence of this taxon. These fossils, the first to establish an age for part of the sedimentary sequence in the Doonerak Anticlinorium, are the oldest fossils yet taken from the central and western Brooks Range.-Authors

  20. Teacher Education in Central Equatoria, South Sudan

    ERIC Educational Resources Information Center

    Hahs Brinkley, Catherine

    2016-01-01

    Without education, many South Sudanese will continue living in poverty. There are numerous factors that limit their educational opportunities including tribal warfare, colonialism, missionary malpractice, civil wars, a high illiteracy rate, low government funding, and threats of war. These factors have left a substantial deficiency in available…

  1. Regional Geochemical Results from the Reanalysis of NURE Stream Sediment Samples - Eagle 3? Quadrangle, East-Central Alaska

    USGS Publications Warehouse

    Crock, J.G.; Briggs, P.H.; Gough, L.P.; Wanty, R.B.; Brown, Z.A.

    2007-01-01

    This report presents reconnaissance geochemical data for a cooperative study in the Fortymile Mining District, east-central Alaska, initiated in 1997. This study has been funded by the U.S. Geological Survey (USGS) Mineral Resources Program. Cooperative funds were provided from various State of Alaska sources through the Alaska Department of Natural Resources. Results presented here represent the initial reconnaissance phase for this multidisciplinary cooperative study. In this phase, 239 sediment samples from the Eagle 3? Quadrangle of east-central Alaska, which had been collected and analyzed for the U.S. Department of Energy's National Uranium Resource Evaluation program (NURE) of the 1970's (Hoffman and Buttleman, 1996; Smith, 1997), are reanalyzed by newer analytical methods that are more sensitive, accurate, and precise (Arbogast, 1996; Taggart, 2002). The main objectives for the reanalysis of these samples were to establish lower limits of determination for some elements and to confirm the NURE data as a reliable predictive reconnaissance tool for future studies in Alaska's Eagle 3? Quadrangle. This study has wide implications for using the archived NURE samples and data throughout Alaska for future studies.

  2. Abundance, trends and distribution of baleen whales off Western Alaska and the central Aleutian Islands

    NASA Astrophysics Data System (ADS)

    Zerbini, Alexandre N.; Waite, Janice M.; Laake, Jeffrey L.; Wade, Paul R.

    2006-11-01

    Large whales were extensively hunted in coastal waters off Alaska, but current distribution, population sizes and trends are poorly known. Line transect surveys were conducted in coastal waters of the Aleutian Islands and the Alaska Peninsula in the summer of 2001-2003. Abundances of three species were estimated by conventional and multiple covariate distance sampling (MCDS) methods. Time series of abundance estimates were used to derive rates of increase for fin whales ( Balaenoptera physalus) and humpback whales ( Megaptera novaeangliae). Fin whales occurred primarily from the Kenai Peninsula to the Shumagin Islands, but were abundant only near the Semidi Islands and Kodiak. Humpback whales were found from the Kenai Peninsula to Umnak Island and were more abundant near Kodiak, the Shumagin Islands and north of Unimak Pass. Minke whales ( B. acutorostrata) occurred primarily in the Aleutian Islands, with a few sightings south of the Alaska Peninsula and near Kodiak Island. Humpback whales were observed in large numbers in their former whaling grounds. In contrast, high densities of fin whales were not observed around the eastern Aleutian Islands, where whaling occurred. Average abundance estimates (95% CI) for fin, humpback and minke whales were 1652 (1142-2389), 2644 (1899-3680), and 1233 (656-2315), respectively. Annual rates of increase were estimated at 4.8% (95% CI=4.1-5.4%) for fin and 6.6% (5.2-8.6%) for humpback whales. This study provides the first estimate of the rate of increase of fin whales in the North Pacific Ocean. The estimated trends are consistent with those of other recovering baleen whales. There were no sightings of blue or North Pacific right whales, indicating the continued depleted status of these species.

  3. Assessment of undiscovered petroleum resources in Central and South America

    USGS Publications Warehouse

    Schenk, C.J.

    2002-01-01

    The USGS has assessed undiscovered conventional oil and gas resources in 128 selected petroleum provinces of the world. Of these 128 provinces, 23 are in South America, Central America, and the Caribbean area. In the USGS 2000 Assessment, the provinces resulted in mean totals for undiscovered resource of 105 billion bbl of oil and 487 tcf of gas. The potential for giant oil and gas fields is greatest in the basins along the Atlantic margin of eastern South America, from the Santos Basin in the south to the Guyana-Suriname Basin in the north. The potential for giant fields is mainly offshore, in water depths up to 3600 m. The South and Central America region ranks third in the world for undiscovered conventional oil and gas behind the Middle East and the Former Soviet Union.

  4. Comparison of UV irradiance measurements at Summit, Greenland; Barrow, Alaska; and South Pole, Antarctica

    NASA Astrophysics Data System (ADS)

    Bernhard, G.; Booth, C. R.; Ehramjian, J. C.

    2008-08-01

    An SUV-150B spectroradiometer for measuring solar ultraviolet (UV) irradiance was installed at Summit, Greenland, in August 2004. Here we compare the initial data from this new location with similar measurements from Barrow, Alaska, and South Pole. Measurements of irradiance at 345 nm performed at equivalent solar zenith angles (SZAs) are almost identical at Summit and South Pole. The good agreement can be explained with the similar location of the two sites on high-altitude ice caps with high surface albedo. Clouds attenuate irradiance at 345 nm at both sites by less than 6% on average, but can reduce irradiance at Barrow by more than 75%. Clear-sky measurements at Barrow are smaller than at Summit by 14% in spring and 36% in summer, mostly due to differences in surface albedo and altitude. Comparisons with model calculations indicate that aerosols can reduce clear-sky irradiance at Summit by 4 6%; aerosol influence is largest in April. Differences in total ozone at the three sites have a large influence on the UV Index. At South Pole, the UV Index is on average 20 80% larger during the ozone hole period than between January and March. At Summit, total ozone peaks in April and UV Indices in spring are on average 10 25% smaller than in the summer. Maximum UV Indices ever observed at Summit, Barrow, and South Pole are 6.7, 5.0, and 4.0, respectively. The larger value at Summit is due to the site's lower latitude. For comparable SZAs, average UV Indices measured during October and November at South Pole are 1.9 2.4 times larger than measurements during March and April at Summit. Average UV Indices at Summit are over 50% greater than at Barrow because of the larger cloud influence at Barrow.

  5. Comparison of UV climates at Summit, Greenland; Barrow, Alaska and South Pole, Antarctica

    NASA Astrophysics Data System (ADS)

    Bernhard, G.; Booth, C. R.; Ehramjian, J. C.

    2008-03-01

    An SUV-150B spectroradiometer for measuring solar ultraviolet (UV) irradiance was installed at Summit, Greenland, in August 2004. Here we compare the initial data from this new location with similar measurements from Barrow, Alaska and South Pole. Measurements of irradiance at 345 nm performed at equivalent solar zenith angles (SZAs) are almost identical at Summit and South Pole. The good agreement can be explained with the similar location of the two sites on high-altitude ice caps with high surface albedo. Clouds have little impact at both sites, but can reduce irradiance at Barrow by more than 75%. Clear-sky measurements at Barrow are smaller than at Summit by 14% in spring and 36% in summer, mostly due to differences in surface albedo and altitude. Comparisons with model calculations indicate that aerosols can reduce clear-sky irradiance at 345 nm by 4-6%; aerosol influence is largest in April. Differences in total ozone at the three sites have a large influence on the UV Index. At South Pole, the UV Index is on average 20-80% larger during the ozone hole period than between January and March. At Summit, total ozone peaks in April and UV Indices in spring are on average 10-25% smaller than in the summer. Maximum UV Indices ever observed at Summit and South Pole are 6.7 and 4.0, respectively. The larger value at Summit is due to the site's lower latitude. For comparable SZAs, average UV Indices measured during October and November at South Pole are 1.9-2.4 times larger than measurements during March and April at Summit. Average UV Indices at Summit are over 50% greater than at Barrow because of the larger cloud influence at Barrow.

  6. Rhyolitic calderas of the Yukon-Tanana Terrane, east central Alaska: volcanic remnants of a mid-Cretaceous magmatic arc

    USGS Publications Warehouse

    Bacon, C.R.; Foster, H.L.; Smith, James G.

    1990-01-01

    Four large but poorly exposed rhyolitic calderas are present in the Yukon-Tanana terrane (YTT) in east central Alaska. At least two are mid-Cretaceous in age (~93 Ma). Similar volcanic rocks, the South Fork Volcanics, occur northeast of the Tintina fault in Yukon Territory. Evidence for the calderas consists of thick deposits of devitrified crystal- and lithic-rich densely welded tuff, interpreted as caldera fill, associated with lava domes or shallow intrusive rocks. Coeval outflow sheets have been largely stripped by erosion. The calderas are preserved within a northeast trending depression extending across the axis of the elongate mid-Cretaceous plutonic province. Trace element abundances in andesites and rhyolites associated with the caldera structures are similar to those of volcanic and plutonic rocks of subduction-related magmatic arcs developed on continental crust and thus are suggestive of formation in such an environment. Late Cretaceous and early Tertiary igneous rocks in the YTT near the calderas are interpreted to have been emplaced in a more extensional setting when the subduction-related magmatic front was farther oceanward. -Authors

  7. Water resources of south-central Missouri

    USGS Publications Warehouse

    Gann, E.E.; Harvey, Edward Joseph; Miller, Don E.

    1976-01-01

    This atlas describes hydrology in an area of approximately 23 ,000 sq mi and includes all or parts of 38 counties in Missouri. The area is bounded on the north by the southern edge of the Missouri River flood plain, on the east by the Mississippi River and the Plateaus-Lowlands boundary (Ozark Escarpment), on the south by the Missouri-Arkansas State line, and on the west by the western drainage divides of the Gasconade and White River basins. The alluvial valley of the Missouri River is excluded. Although the populations of several rural counties in the area have declined in recent years, significant population increases have occurred in the vicinity of the two principal population centers, St. Louis in the northeast and Springfield in the southwest. Future population increases are expected to occur as a result of continued urban expansion, increased recreational use of land and water resources, and additional development of the mining industry. (Woodard-USGS)

  8. Surficial Geologic Map of the Tanacross B-4 Quadrangle, East-Central Alaska

    USGS Publications Warehouse

    Carrara, Paul E.

    2006-01-01

    The Tanacross B-4 1:63,360-scale quadrangle, through which the Alaska Highway runs, is in east-central Alaska about 100 mi west of the Yukon border. The surficial geologic mapping in the quadrangle is in support of the 'Geologic Mapping in support of land, resources, and hazards issues in Alaska' Project of the USGS National Cooperative Geologic Mapping Program. The Tanacross B-4 quadrangle contains parts of two physiographic provinces, the Yukon-Tanana Upland and the Northway-Tanana Lowland. The gently rolling hills of the Yukon-Tanana Upland, in the northern and eastern map area, rise to about 3,100 ft. The Northway-Tanana Lowland, in the western and southern map area, contains the westerly flowing Tanana River. Elevations along the floor of the lowland generally range between 1,540 and 1,700 ft. The dominant feature within the map is the Tok fan, which occupies about 20 percent of the map area. This large, nearly featureless fan contains a high percentage of volcanic clasts derived from outside the present-day drainage of the Tok River. The map provides interpretations of the Quaternary surficial deposits and associated geologic hazards in this area of the upper Tanana valley. Because the map area is dominated by various surficial deposits, the map depicts 13 different Quaternary surficial units consisting of man-made, alluvial, colluvial, organic, lacustrine, and eolian deposits. Deposits shown on this map are generally greater than 1 m thick. The map is accompanied by a text containing unit descriptions incorporating information pertaining to material type, location, associated hazards, resource use (if any), and thickness.

  9. Crustal insights from gravity and aeromagnetic analysis: Central North Slope, Alaska

    USGS Publications Warehouse

    Saltus, R.W.; Potter, C.J.; Phillips, J.D.

    2006-01-01

    Aeromagnetic and gravity data are processed and interpreted to reveal deep and shallow information about the crustal structure of the central North Slope, Alaska. Regional aeromagnetic anomalies primarily reflect deep crustal features. Regional gravity anomalies are more complex and require detailed analysis. We constrain our geophysical models with seismic data and interpretations along two transects including the Trans-Alaska Crustal Transect. Combined geophysical analysis reveals a remarkable heterogeneity of the pre-Mississippian basement. In the central North Slope, pre-Mississippian basement consists of two distinct geophysical domains. To the southwest, the basement is dense and highly magnetic; this basement is likely mafic and mechanically strong, possibly acting as a buttress to basement involvement in Brooks Range thrusting. To the northeast, the central North Slope basement consists of lower density, moderately magnetic rocks with several discrete regions (intrusions?) of more magnetic rocks. A conjugate set of geophysical trends, northwest-southeast and southwest-northeast, may be a factor in the crustal response to tectonic compression in this domain. High-resolution gravity and aeromagnetic data, where available, reflect details of shallow fault and fold structure. The maps and profile models in this report should provide useful guidelines and complementary information for regional structural studies, particularly in combination with detailed seismic reflection interpretations. Future challenges include collection of high-resolution gravity and aeromagnetic data for the entire North Slope as well as additional deep crustal information from seismic, drilling, and other complementary methods. Copyrights ?? 2006. The American Association of Petroleum Geologists. All rights reserved.

  10. Paleobiogeographic affinities of emsian (late early devonian) gastropods from farewell terrane (west-central Alaska)

    USGS Publications Warehouse

    Fryda, J.; Blodgett, R.B.

    2008-01-01

    The vast majority of Emsian gastropods from Limestone Mountain, Medfra B-4 quadrangle, west-central Alaska (Farewell terrane) belong to species with lecithotrophic larval strategy. The present data show that there is no significant difference in the paleobiogeo-graphic distribution of Emsian gastropod genera with lecithotrophic and planktotrophic larval strategies. Numerical analysis of the faunal affinities of the Emsian gastropod fauna from the Farewell terrane reveals that this terrane has much stronger faunal connections to regions like Variscan Europe, eastern Australia, and the Alexander terrane of southeast Alaska than to cratonic North America (Laurentia). The Canadian Arctic Islands is the only region of cratonic North America (Laurentia) that shows significant faunal affinities to the Emsian gastropod faunas of the Farewell terrane. The analysis also indicates a close faunal link between the Farewell and Alexander terranes. Published paleontological and geological data suggest that the Farewell and Alexander terranes represents tectonic entities that have been rifted away from the Siberia, Baltica, or the paleo-Pacific margin of Australia. The results of the present numerical analysis are not in conflict with any of these possibilities. However, the principle of spatial continuity of the wandering path prefers Siberia as the most probable "parental" paleocontinent for the derivation of both the Farewell and Alexander terranes. ?? 2008 The Geological Society of America.

  11. 75 FR 73981 - Fisheries of the Exclusive Economic Zone Off Alaska; Big Skate in the Central Regulatory Area of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-30

    ... of the Gulf of Alaska (GOA). This action is necessary because the 2010 total allowable catch (TAC) of... accordance with the FMP appear at subpart H of 50 CFR part 600 and 50 CFR part 679. The 2010 TAC of big skate... that the 2010 TAC of big skate in the Central Regulatory Area of the GOA has been reached....

  12. 77 FR 67579 - Fisheries of the Exclusive Economic Zone Off Alaska; Reallocation of Pacific Cod in the Central...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-13

    ... Management Area AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric... vessels using jig gear in the Central Regulatory Area of the Gulf of Alaska management area. This action is necessary to allow the 2012 total allowable catch of Pacific cod to be harvested. DATES:...

  13. 50 CFR Figure 7 to Subpart E of... - Western and Central Alaska Rural and Non-Rural Areas

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 50 Wildlife and Fisheries 9 2011-10-01 2011-10-01 false Western and Central Alaska Rural and Non-Rural Areas 7 Figure 7 to Subpart E of Part 300 Wildlife and Fisheries INTERNATIONAL FISHING AND RELATED ACTIVITIES INTERNATIONAL FISHERIES REGULATIONS Pacific Halibut Fisheries Pt. 300, Subpt. E, Fig. 7 Figure...

  14. 50 CFR Figure 7 to Subpart E of... - Western and Central Alaska Rural and Non-Rural Areas

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 50 Wildlife and Fisheries 11 2013-10-01 2013-10-01 false Western and Central Alaska Rural and Non-Rural Areas 7 Figure 7 to Subpart E of Part 300 Wildlife and Fisheries INTERNATIONAL FISHING AND RELATED ACTIVITIES INTERNATIONAL FISHERIES REGULATIONS Pacific Halibut Fisheries Pt. 300, Subpt. E, Fig. 7 Figure...

  15. 76 FR 14898 - South Central Idaho Resource Advisory Committee

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-18

    ...: Notice of meeting. SUMMARY: The South Central Idaho Resource Advisory Committee will meet in Sun Valley... meeting will be held March 30, 2011, 9:30 a.m. ADDRESSES: The meeting will be held at the Sun Valley City Hall Council Chambers, 810 Elkhorn Road, Sun Valley, Idaho 83353. Written comments should be sent...

  16. 18. SOUTH CENTRAL SECTION OF HISTORIC DISTRICT LOOKING NORTH TO ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    18. SOUTH CENTRAL SECTION OF HISTORIC DISTRICT LOOKING NORTH TO WATER TOWER (Buildings No. 43, 42, 78) (Copy negative made from National Archives negative No. 92-F-61B-5) - Fort Sheridan, 25 miles Northeast of Chicago, on Lake Michigan, Lake Forest, Lake County, IL

  17. 75 FR 8645 - South Central Idaho Resource Advisory Council

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-02-25

    ..., USDA. ACTION: Notice of meeting. SUMMARY: The South Central Idaho RAC will meet in Twin Falls, Idaho... meeting will be held at The Red Lion Canyon Springs Hotel, 1357 Blue Lakes Blvd. North, Twin Falls, Idaho... Road East, Twin Falls, Idaho 83301. Comments may also be sent via e-mail to jathomas@fs.fed.us , or...

  18. GENERAL VIEW FROM THE SOUTH, SHOWING CENTRAL COMPLEX WITH THE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    GENERAL VIEW FROM THE SOUTH, SHOWING CENTRAL COMPLEX WITH THE STOCK BINS FOR RAW MATERIALS IN THE FOREGROUND, FOUR LARGE BOILER UNITS AND STOVE'S AND THE #1 BLAST FURNACE WITH SKIP HOIST IN THE BACKGROUND. - Sloss-Sheffield Steel & Iron, First Avenue North Viaduct at Thirty-second Street, Birmingham, Jefferson County, AL

  19. Introduction: seismology and earthquake engineering in Central and South America.

    USGS Publications Warehouse

    Espinosa, A.F.

    1983-01-01

    Reports the state-of-the-art in seismology and earthquake engineering that is being advanced in Central and South America. Provides basic information on seismological station locations in Latin America and some of the programmes in strong-motion seismology, as well as some of the organizations involved in these activities.-from Author

  20. 25. Central tension lock looking straight down, south span is ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    25. Central tension lock looking straight down, south span is to the left, north span to the right. there are three tension locks just below road level. - Henry Ford Bridge, Spanning Cerritos Channel, Los Angeles-Long Beach Harbor, Los Angeles, Los Angeles County, CA

  1. ELECTRICAL LINES ARRIVE FROM CENTRAL FACILITIES AREA, SOUTH OF MTR. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    ELECTRICAL LINES ARRIVE FROM CENTRAL FACILITIES AREA, SOUTH OF MTR. EXCAVATION RUBBLE IN FOREGROUND. CONTRACTOR CRAFT SHOPS, CRANES, AND OTHER MATERIALS ON SITE. CAMERA FACES EAST, WITH LITTLE BUTTE AND MIDDLE BUTTE IN DISTANCE. INL NEGATIVE NO. 335. Unknown Photographer, 7/1/1950 - Idaho National Engineering Laboratory, Test Reactor Area, Materials & Engineering Test Reactors, Scoville, Butte County, ID

  2. This image, looking due south shows the central part of ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    This image, looking due south shows the central part of the north wing of the building, a 2 story facade. In the foreground are several utility chases which span this elevation of the building - Department of Energy, Mound Facility, Electronics Laboratory Building (E Building), One Mound Road, Miamisburg, Montgomery County, OH

  3. Ocean plateau-seamount origin of basaltic rocks, Angayucham terrane, central Alaska

    USGS Publications Warehouse

    Barker, F.; Jones, D.L.; Budahn, J.R.; Coney, P.J.

    1988-01-01

    The Angayucham terrane of north-central Alaska (immediately S of the Brooks Range) is a large (ca. 500 km E-W), allochthonous complex of Devonian to Lower Jurassic pillow basalt, diabase sills, gabbro plutons, and chert. The mafic rocks are transitional normal-to-enriched, mid-ocean-ridge (MORB) type tholeiites (TiO2 1.2-3.4%, Nb 7-23 ppm, Ta 0.24-1.08 ppm, Zr 69-214 ppm, and light REE's slightly depleted to moderately enriched). Geologic and geochemical constraints indicate that Angayucham terrane is the upper "skin' (ca. 3-4 km thick) of a long-lived (ca. 170-200 ma) oceanic plateau whose basaltic-gabbroic rocks are like those of seamounts of the East Pacific Rise. -Authors

  4. Upper triassic continental margin strata of the central alaska range: Implications for paleogeographic reconstruction

    USGS Publications Warehouse

    Till, A.B.; Harris, A.G.; Wardlaw, B.R.; Mullen, M.

    2007-01-01

    Reexamination of existing conodont collections from the central Alaska Range indicates that Upper Triassic marine slope and basin rocks range in age from at least as old as the late Carnian to the early middle Norian. The conodont assemblages typical of these rocks are generally cosmopolitan and do not define a distinct paleogeographic faunal realm. One collection, however, containsEpigondolella multidentata sensu Orchard 1991c, which appears to be restricted to western North American autochthonous rocks. Although paleogeographic relations cannot be determined with specificity, the present distribution of biofaces within the Upper Triassic sequence could not have been the result of simple accordion-style collapse of the Late Triassic margin.

  5. Detrital Zircon Geochronology of Cretaceous and Paleogene Strata Across the South-Central Alaskan Convergent Margin

    USGS Publications Warehouse

    Bradley, Dwight; Haeussler, Peter; O'Sullivan, Paul; Friedman, Rich; Till, Alison; Bradley, Dan; Trop, Jeff

    2009-01-01

    Ages of detrital zircons are reported from ten samples of Lower Cretaceous to Paleogene metasandstones and sandstones from the Chugach Mountains, Talkeetna Mountains, and western Alaska Range of south-central Alaska. Zircon ages are also reported from three igneous clasts from two conglomerates. The results bear on the regional geology, stratigraphy, tectonics, and mineral resource potential of the southern Alaska convergent margin. Chugach Mountains - The first detrital zircon data are reported here from the two main components of the Chugach accretionary complex - the inboard McHugh Complex and the outboard Valdez Group. Detrital zircons from sandstone and two conglomerate clasts of diorite were dated from the McHugh Complex near Anchorage. This now stands as the youngest known part of the McHugh Complex, with an inferred Turonian (Late Cretaceous) depositional age no older than 91-93 Ma. The zircon population has probability density peaks at 93 and 104 Ma and a smattering of Early Cretaceous and Jurassic grains, with nothing older than 191 Ma. The two diorite clasts yielded Jurassic U-Pb zircon ages of 179 and 181 Ma. Together, these findings suggest a Mesozoic arc as primary zircon source, the closest and most likely candidate being the Wrangellia composite terrane. The detrital zircon sample from the Valdez Group contains zircons as young as 69 and 77 Ma, consistent with the previously assigned Maastrichtian to Campanian (Late Cretaceous) depositional age. The zircon population has peaks at 78, 91, 148, and 163 Ma, minor peaks at 129, 177, 330, and 352 Ma, and no concordant zircons older than Devonian. A granite clast from a Valdez Group conglomerate yielded a Triassic U-Pb zircon age of 221 Ma. Like the McHugh Complex, the Valdez Group appears to have been derived almost entirely from Mesozoic arc sources, but a few Precambrian zircons are also present. Talkeetna Mountains - Detrital zircons ages were obtained from southernmost metasedimentary rocks of the

  6. The south-central United States magnetic anomaly

    NASA Technical Reports Server (NTRS)

    Starich, P. J.; Hinze, W. J.; Braile, L. W.

    1985-01-01

    A positive magnetic anomaly, which dominates the MAGSAT scalar field over the south-central United States, results from the superposition of magnetic effects from several geologic sources and tectonic structures in the crust. The highly magnetic basement rocks of this region show good correlation with increased crustal thickness, above average crustal velocity and predominantly negative free-air gravity anomalies, all of which are useful constraints for modeling the magnetic sources. The positive anomaly is composed of two primary elements. The western-most segment is related to middle Proterozoic granite intrusions, rhyolite flows and interspersed metamorphic basement rocks in the Texas panhandle and eastern New Mexico. The anomaly and the magnetic crust are bounded to the west by the north-south striking Rio Grande Rift. The anomaly extends eastward over the Grenville age basement rocks of central Texas, and is terminated to the south and east by the buried extension of the Ouachita System. The northern segment of the anomaly extends eastward across Oklahoma and Arkansas to the Mississippi Embayment. It corresponds to a general positive magnetic region associated with the Wichita Mountains igneous complex in south-central Oklahoma and 1.2 to 1.5 Ga. felsic terrane to the north.

  7. Central Energy System Modernization at Fort Jackson, South Carolina

    SciTech Connect

    Brown, Daryl R.; Chvala, William D.; Dirks, James A.

    2006-11-29

    An evaluation of technology options was conducted for the central energy systems at Fort Jackson, South Carolina. There were two objectives in conducting this study. From a broader viewpoint, the Army would like to develop a systematic approach to management of its central energy systems and selected Fort Jackson for this ''pilot'' study for a prospective Central Energy System Modernization Program. From a site-specific perspective, the objective was to identify the lowest life-cycle cost energy supply option(s) at Fort Jackson for buildings currently served by central boilers and chillers. This study was co-funded by the Army's Southeast Region and the U.S. Department of Energy's Federal Energy Management Program.

  8. Stratiform zinc-lead mineralization in Nasina assemblage rocks of the Yukon-Tanana Upland in east-central Alaska

    USGS Publications Warehouse

    Dusel-Bacon, Cynthia; Bressler, Jason R.; Takaoka, Hidetoshi; Mortensen, James K.; Oliver, Douglas H.; Leventhal, Joel S.; Newberry, Rainer J.; Bundtzen, Thomas K.

    1998-01-01

    The Yukon-Tanana Upland of east-central Alaska and Yukon comprises thrust sheets of ductilely deformed metasedimentary and metaigneous rocks of uncertain age and origin that are overlain by klippen of weakly metamorphosed oceanic rocks of the Seventymile-Slide Mountain terrane, and intruded by post-kinematic Early Jurassic, Cretaceous and Tertiary granitoids. Metamorphosed continental margin strata in the Yukon-Tanana Upland of east-central Alaska are thought to be correlative, on the basis of stratigraphic similarities and sparse Mississippian U-Pb zircon and fossil ages (Mortensen, 1992), with middle Paleozoic metasedimentary and metavolcanic rocks in the eastern Alaska Range and in western and southeastern Yukon. Furthermore, rocks in the northern Yukon-Tanana Upland may correlate across the Tintina fault with unmetamorphosed counterparts in the Selwyn Basin (Murphy and Abbott, 1995). Volcanic-hosted (VMS) and sedimentary exhalative (sedex) massive sulfide occurrences are widely reported for these other areas (green-colored unit of fig. 1) but, as yet, have not been documented in the Alaskan part of the Yukon-Tanana Upland. Recent discoveries of VMS deposits in Devono-Mississippian metavolcanic rocks in the Finlayson Lake area of southeastern Yukon (Hunt, 1997) have increased the potential for finding VMS deposits in rocks of similar lithology and age in the Yukon-Tanana Upland of Alaska. Restoration of 450 km of early Tertiary dextral movement along the Tintina fault juxtaposes these two areas.

  9. Inventory of marine and estuarine fishes in southeast and central Alaska National Parks

    USGS Publications Warehouse

    Arimitsu, M.L.; Litzow, Michael A.; Piatt, J.F.; Robards, Martin D.; Abookire, Alisa A.; Drew, G.S.

    2003-01-01

    As part of a national inventory program funded by the National Park Service, we conducted an inventory of marine and estuarine fishes in Glacier Bay National Park and Preserve, Wrangell-St. Elias National Park and Preserve, Sitka National Historical Park, and Klondike Gold Rush National Historical Park in 2001 and 2002. In addition, marine fish data from a previous project that focused on forage fishes and marine predators during 1999 and 2000 in Glacier Bay proper were compiled for this study. Sampling was conducted with modified herring and Isaacs-Kidd midwater trawls, a plumb staff beam trawl, and beach seines. Species lists of relative abundance were generated for nearshore fishes in all parks, and for demersal and pelagic fishes in Glacier Bay National Park and Preserve and Wrangell-St. Elias National Park and Preserve. With a total sampling effort of 531 sets, we captured 100 species in Glacier Bay National Park and Preserve, 31 species in Wrangell-St. Elias National Park and Preserve, 23 species in Sitka National Historical Park, and 11 species in Klondike Gold Rush National Historical Park. We estimated that between 59 and 85 percent of the total marine fish species present were sampled by us in the various habitat-park units. We also combined these data with historical records and prepared an annotated species list of 160 marine and estuarine fishes known to occur in Glacier Bay National Park and Preserve. Shannon-Wiener diversity index and catch per unit effort were used to assess the effects of depth and latitude (distance from tidewater glaciers) on marine fish community ecology in Glacier Bay proper. Our findings suggest that demersal fishes are more abundant and diverse with increased distance from tidewater glaciers, and that pelagic fishes sampled deeper than 50 m are more abundant in areas closer to tidewater glaciers. Fish, Marine, Estuarine, National Parks, Southeast Alaska, Central Alaska, Inventory, Monitoring, Diversity, Abundance, Glacier Bay

  10. Trends of ice breakup date in south-central Ontario

    NASA Astrophysics Data System (ADS)

    Fu, Congsheng; Yao, Huaxia

    2015-09-01

    Large-scale ice phenology studies have revealed overall patterns of later freeze, earlier breakup, and shorter duration of ice in the Northern Hemisphere. However, there have been few studies regarding the trends, including their spatial patterns, in ice phenology for individual waterbodies on a local or small regional scale, although the coherence of ice phenology has been shown to decline rapidly in the first few hundred kilometers. In this study, we extracted trends, analyzed affecting factors, and investigated relevant spatial patterns for ice breakup date time series at 10 locations with record length ≥90 years in south-central Ontario, Canada. Wavelet methods, including the multiresolution analysis (MRA) method for nonlinear trend extraction and the wavelet coherence (WTC) method for identifying the teleconnections between large-scale climate modes and ice breakup date, are proved to be effective in ice phenology analysis. Using MRA method, the overall trend of ice breakup date time series (1905-1991) varied from earlier ice breakup to later ice breakup, then to earlier breakup again from south to north in south-central Ontario. Ice breakup date is closely correlated with air temperature during certain winter/spring months, as well as the last day with snow on the ground and number of snow-on-ground days. The influences of solar activity and Pacific North American on ice breakup were comparatively uniform across south-central Ontario, while those of El Niño-Southern Oscillation, North Atlantic Oscillation, and Arctic Oscillation on ice phenology changed with distance of 50-100 km in the north-south direction.

  11. Combined Ice and Water Balances of Maclure Glacier, California, South Cascade Glacier, Washington, and Wolverine and Gulkana Glaciers, Alaska, 1967 Hydrologic Year

    USGS Publications Warehouse

    Tangborn, Wendell V.; Mayo, Lawrence R.; Scully, David R.; Krimmel, Robert M.

    1977-01-01

    Combined ice and water balances were measured in the 1967 hydrologic year (October 1-September 30) on four glaciers in western North America ranging in latitude from 37 deg to 63 deg N. This hydrologic year was characterized by heavier than normal winter precipitation in California and Washington and abnormally dry winter conditions in coastal Alaska. In summer the western conterminous states were abnormally dry and central and southern Alaska experienced very wet conditions. Maclure Glacier (lat 37 deg 45' N., 3,650-m (metres) mean equilibrium line altitude) had an above normal winter balance of 3.46 m and a positive annual balance of 1.05 m (metres of water equivalent). South Cascade Glacier (lat 48 deg 22' N., 1900-m mean equilibrium line altitude) had a winter balance of 3.28 m, slightly above average. Above normal summer ablation resulted in a final annual balance of -0.58 m, slightly more negative than has been the case for the past decade. Wolverine Glacier's (lat 60 deg 24' N., 1,200-m mean equilibrium line altitude) winter balance was 1.17 m, considerably below normal; the annual balance was -2.04 m. Gulkana Glacier (lat 63 deg 15' N., 1,700-m mean equilibrium line altitude) had a winter balance of 1.05 m, approximately normal for this glacier; the final annual balance was -0.30 m.

  12. South America, Central America, the Caribbean, and Mexico

    SciTech Connect

    Deal, C.

    1981-10-01

    Summaries of oil and gas drillings, well completions, production, exploratory wells, exploration activity and wildcat drilling were given for South America, Central America, the Caribbean, and Mexico. The countries, islands, etc. included Argentina, Bahamas, Barbados, Belize, Bolivia, Brazil, Colombia, Costa Rica, Cuba, Dominican Republic, Ecuador, French Guiana, Guatemala, Guyana, Haiti, Honduras, Jamaica, Leeward and Windward Islands, Mexico, Netherlands Antilles, Nicaragua, Panama, Paraguay, Peru, Puerto Rico, El Salvador, Surinam, Trinidad and Venezuela. 16 figures, 120 tables. (DP)

  13. 40 CFR 81.166 - South Central Coast Intrastate Air Quality Control Region.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 17 2011-07-01 2011-07-01 false South Central Coast Intrastate Air... Air Quality Control Regions § 81.166 South Central Coast Intrastate Air Quality Control Region. The South Central Coast Intrastate Air Quality Control Region (California) consists of the territorial...

  14. 40 CFR 81.260 - South Central Iowa Intrastate Air Quality Control Region.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 18 2014-07-01 2014-07-01 false South Central Iowa Intrastate Air... Air Quality Control Regions § 81.260 South Central Iowa Intrastate Air Quality Control Region. The South Central Iowa Intrastate Air Quality Control Region consists of the territorial area encompassed...

  15. 40 CFR 81.260 - South Central Iowa Intrastate Air Quality Control Region.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 17 2010-07-01 2010-07-01 false South Central Iowa Intrastate Air... Air Quality Control Regions § 81.260 South Central Iowa Intrastate Air Quality Control Region. The South Central Iowa Intrastate Air Quality Control Region consists of the territorial area encompassed...

  16. 40 CFR 81.260 - South Central Iowa Intrastate Air Quality Control Region.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 18 2013-07-01 2013-07-01 false South Central Iowa Intrastate Air... Air Quality Control Regions § 81.260 South Central Iowa Intrastate Air Quality Control Region. The South Central Iowa Intrastate Air Quality Control Region consists of the territorial area encompassed...

  17. 40 CFR 81.260 - South Central Iowa Intrastate Air Quality Control Region.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 17 2011-07-01 2011-07-01 false South Central Iowa Intrastate Air... Air Quality Control Regions § 81.260 South Central Iowa Intrastate Air Quality Control Region. The South Central Iowa Intrastate Air Quality Control Region consists of the territorial area encompassed...

  18. 40 CFR 81.260 - South Central Iowa Intrastate Air Quality Control Region.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 18 2012-07-01 2012-07-01 false South Central Iowa Intrastate Air... Air Quality Control Regions § 81.260 South Central Iowa Intrastate Air Quality Control Region. The South Central Iowa Intrastate Air Quality Control Region consists of the territorial area encompassed...

  19. 40 CFR 81.166 - South Central Coast Intrastate Air Quality Control Region.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 18 2013-07-01 2013-07-01 false South Central Coast Intrastate Air... Air Quality Control Regions § 81.166 South Central Coast Intrastate Air Quality Control Region. The South Central Coast Intrastate Air Quality Control Region (California) consists of the territorial...

  20. Functional Assessment of Alaska Peatlands in Cook Inlet Basin, Region 10 Regional Applied Research Effort (RARE)

    EPA Science Inventory

    Peatlands in south central Alaska are the dominant wetland class in the lowlands of the Cook Inlet Basin. Currently Alaska peatlands are extensive and largely pristine but these areas are facing increasing human development. This study focused on obtaining measures of ecologica...

  1. Distribution of burrowing owls in east-central South Dakota

    USGS Publications Warehouse

    Shaffer, Jill A; Thiele, Jason P.

    2013-01-01

    Western burrowing owl (Athene cunicularia hypugaea) populations have declined across much of western North America, particularly at the northern and eastern edges of the species’ breeding range (Martell et al. 2001, Murphy et al. 2001, Shyry et al. 2001, Skeel et al. 2001, Klute et al. 2003). In South Dakota, the burrowing owl is a summer resident that historically was relatively common throughout the state, but its range has decreased in recent decades, especially in the eastern half of the state (Whitney et al. 1978, South Dakota Ornithologists’ Union [SDOU] 1991, Peterson 1995). Tallman et al. (2002) described the species as uncommon to locally common in western South Dakota, uncommon in the north-central part of the state, and casual (i.e., not within the species’ normal range, but with 3–10 records in the past 10 years) elsewhere in the eastern half. The burrowing owl is a Species of Greatest Conservation Need (South Dakota Department of Game, Fish and Parks [SDGFP] 2006) and a Level I Priority Species in South Dakota (Bakker 2005).

  2. Reconnaissance for radioactive deposits in Alaska, 1953

    USGS Publications Warehouse

    Matzko, John J.; Bates, Robert G.

    1955-01-01

    During the summer of 1953 the areas investigated for radioactive deposits in Alaska were on Nikolai Creek near Tyonek and on Likes Creek near Seward in south-central Alaska where carnotite-type minerals had been reported; in the headwaters of the Peace River in the eastern part of the Seward Peninsula and at Gold Bench on the South Fork of the Koyukuk River in east-central Alaska, where uranothorianite occurs in places associated with base metal sulfides and hematite; in the vicinity of Port Malmesbury in southeastern Alaska to check a reported occurrence of pitchblende; and, in the Miller House-Circle Hot Springs area of east-central Alaska where geochemical studies were made. No significant lode deposits of radioactive materials were found. However, the placer uranothorianite in the headwaters of the Peace River yet remains as an important lead to bedrock radioactive source materials in Alaska. Tundra cover prevents satisfactory radiometric reconnaissance of the area, and methods of geochemical prospecting such as soil and vegetation sampling may ultimately prove more fruitful in the search for the uranothorianite-sulfide lode source than geophysical methods.

  3. Evidence for formation of a flexural backarc basin by compression and crustal thickening in the central Alaska peninsula

    SciTech Connect

    Bond, G.C.; Lewis, S.D.; Taber, J.; Steckler, M.S.; Kominz, M.A. )

    1988-12-01

    The North Aleutian Basin is a large, Cenozoic sedimentary basin in the northern part of the central Alaska Peninsula and the southern Bering shelf. The gravity anomaly pattern, the geometry, and the structure of the basin suggest that if formed by downward flexure of the backarc lithosphere. Basin modeling suggests that the flexure was driven by the emplacement of surface and subsurface loads having densities comparable to those of oceanic crust and mantle rocks, at approximately the position of the present-day volcanic arc and forearc. The authors suggest that the inferred loads consist of tectonically thickened mafic crustal materials lying beneath the arc and forearc of the central Alaska Peninsula. The crustal thickening may have occurred within a dominantly transpressional regime resulting from oblique convergence between the North American and Pacific plates during the Cenozoic.

  4. 3D potential-field model of a Triassic Nikolai large igneous province vent, central Alaska Range

    NASA Astrophysics Data System (ADS)

    Glen, J. M.; Schmidt, J. M.; Connard, G. G.

    2009-12-01

    The southern flank of the Alaska Range in south central Alaska exposes a thick, fresh sequence of Middle to Late Triassic Nikolai Greenstone. At least 5 ultramafic intrusive complexes and numerous gabbroic sills of similar age intrude Pennsylvanian to Triassic volcanogenic and sedimentary rocks below the Nikolai. The 2 largest and best exposed ultramafic complexes are the Fish Lake and Tangle ultramafic sills on the north, and south flanks, respectively of the Amphitheater Mountains synform. Three-dimensional (3D) modeling of gravity and magnetic data, using the GMSYS-3D modeling software, shows details of the Amphitheater Mountains structure, Nikolai basalt thickness, and geometry of the apparently connected Fish Lake and Tangle ultramafic sills. Modeling is based on a compilation of existing regional and newly-acquired detailed profile gravity data, a compilation of regional and high-resolution aeromagnetic surveys, and numerous rock-property data (including density, susceptibility, and magnetic remanence measurements of outcrops, hand samples, and drill cores). Eight intersecting 2D models, constructed prior to the 3D model, suggested the presence of an elongate ultramafic keel below the Amphitheater synform axis and extensive gabbroic satellite sills below the Fish Lake and Tangle ultramafic complexes. The 3D model (50x70km) includes the full geographic extent of the Fish Lake and Tangle bodies, as well as parts of the Rainy and Canwell complexes to the north and east of the Amphitheater Mountains. Eleven layers were initially constructed from horizons we exported from the 2D models and gridded to form layer surfaces. Individual 3D model layers were subsequently modified by both forward and inverse methods applied to the layer surfaces and properties (density and magnetic susceptibility) to reduce differences between the observed and calculated gravity and magnetic grids. Up to 2 km of Nikolai basalts form the center of the asymmetric, west-plunging, 50 km long

  5. Reconnaissance for radioactive deposits in the Fairbanks and Livengood Quadrangles, east-central Alaska, 1949

    USGS Publications Warehouse

    Wedow, H.; Stevens, J.M.; Tolbert, G.E.

    1953-01-01

    Several mines and prospects in the Fairbanks and Livengood quadrangles, east-central Alaska, were examined for the possible presence of radioactive materials in the summer of 1949. Also tested were pre-Cambrian and Paleozoic metamorphic and sedimentary rocks crossed by the Elliott Highway, which extends from Fox, near Fairbanks, northward about 70 miles to the town of Livengood. None of the lodes tested exhibited radioactivity in excess of 0.003 percent equivalent uranium, although nuggets consisting chiefly of native bismuth and containing as much as 0.1 percent equivalent uranium had been found previously in a placer on Fish Creek several miles below the reported bismuth-bearing lode on Melba Creek. The greatest radioactivity found in the rocks along the Elliott Highway was in an iron-stained schist of pre-Cambrian age and in carbonaceous shale of Middle Devonian or Carboniferous age. Respective samples of these rocks contain 0.003 and 0.004 percent equivalent uranium. A possible local bedrock source for a euxenite-polycrase mineral found in a placer concentrate containing about 0.04 percent equivalent uranium was sought in the watershed of Goodluck Creek, near Livengood. The bedrock source of this mineral could not be located; it is believed that the source could be outside of the Goodluck watershed, as drainage changes in the area during Quaternary time might well have introduced gravels from nearby areas.

  6. Denali fault slip rates and Holocene-late Pleistocene kinematics of central Alaska

    USGS Publications Warehouse

    Matmon, A.; Schwartz, D.P.; Haeussler, P.J.; Finkel, R.; Lienkaemper, J.J.; Stenner, Heidi D.; Dawson, T.E.

    2006-01-01

    The Denali fault is the principal intracontinental strike-slip fault accommodating deformation of interior Alaska associated with the Yakutat plate convergence. We obtained the first quantitative late Pleistocene-Holocene slip rates on the Denali fault system from dating offset geomorphic features. Analysis of cosmogenic 10Be concentrations in boulders (n = 27) and sediment (n = 13) collected at seven sites, offset 25-170 m by the Denali and Totschunda faults, gives average ages that range from 2.4 ± 0.3 ka to 17.0 ± 1.8 ka. These offsets and ages yield late Pleistocene-Holocene average slip rates of 9.4 ± 1.6, 12.1 ± 1.7, and 8.4 ± 2.2 mm/yr-1 along the western, central, and eastern Denali fault, respectively, and 6.0 ± 1.2 mm/yr-1 along the Totschunda fault. Our results suggest a westward decrease in the mean Pleistocene-Holocene slip rate. This westward decrease likely results from partitioning of slip from the Denali fault system to thrust faults to the north and west. 2006 Geological Society of America.

  7. Geologic Map of the Big Delta B-1 Quadrangle, East-Central Alaska

    USGS Publications Warehouse

    Day, Warren C.; O'Neill, J. Michael; Aleinikoff, John N.; Green, Gregory N.; Saltus, Richard W.; Gough, Larry P.

    2007-01-01

    Geologic mapping and U-Pb age dating of rocks from the Big Delta B-1 quadrangle, east-central Alaska, have yielded new insights into the geology and gold mineral resource for the headwater region of the Goodpaster River, northeast of Delta, Alaska. The area lies within the Yukon-Tanana Upland and is underlain by Paleozoic and Cretaceous crystalline bedrock and contains several gold mines and prospects. The Paleozoic units include biotite gneiss, quartzite interlayered with metapelite, and amphibolite gneiss. The Paleozoic units were intruded during the Devonian by tonalitic to granitic plutons, which, as a result of regional Mesozoic metamorphism and tectonism, are now augen gneiss and biotite orthogneiss. The Mesozoic regional metamorphism and ductile deformation of the entire Yukon-Tanana Upland culminated by the Late Cretaceous (about 116 Ma) as a result of northwest-directed regional transpression along the southern margin of the North American craton. This dynamothermal episode was followed by invasion of syn- to post-tectonic granodioritic to granitic batholiths during the Late Cretaceous (about 113-107 Ma), followed by a pulse of 100-95 Ma quartz feldspar porphyry intrusions. Gold mineralization is spatially associated with various post-tectonic Late Cretaceous granitic dikes and batholiths throughout the quadrangle. A northeast-trending structural corridor, described herein as the Black Mountain tectonic zone, both controlled the emplacement of some of the Cretaceous intrusive rocks, gold deposits, and prospects, as well as formed a deep-seated crustal conduit along which a subsequent rhyolite flow-dome complex erupted during the Paleocene. Tertiary uplift and erosion resulted in the development of extensive erosional pediments. Quaternary alpine glaciation carved beautiful, broad valleys in the eastern part of the quadrangle, leaving behind terminal moraines in the headwater region of the Goodpaster river drainage. Continued Holocene to Recent deformation

  8. Populations and productivity of seabirds at South Marble Island, Glacier Bay, Alaska, during May-July, 1999

    USGS Publications Warehouse

    Zador, Stephani G.; Piatt, John F.

    1999-01-01

    In the course of directed research on glaucous-winged gulls, we investigated the numbers and activities of all breeding and non-breeding seabirds associated with South Marble Island in Glacier Bay, Alaska, during mid-May to late July, 1999. Most observations were made from the island; additional observations were made during transportation to and from the island. Data were collected on the presence and numbers of all seabirds observed. Detailed information on breeding chronology and productivity were also collected for glaucous-winged gulls (Larus glaucescens), pigeon guillemots (Cepphus columba), black-legged kittiwakes (Rissa tridactyla), and black oystercatchers (Haemantopus bachmani).

  9. Geologic Map and Engineering Properties of the Surficial Deposits of the Tok Area, East-Central Alaska

    USGS Publications Warehouse

    Carrara, Paul E.

    2007-01-01

    The Tok area 1:100,000-scale map, through which the Alaska Highway runs, is in east-central Alaska about 160 km west of the Yukon border. The surficial geologic mapping in the map area is in support of the 'Geologic Mapping in support of land, resources, and hazards issues in Alaska' Project of the USGS National Cooperative Geologic Mapping Program. The Tok map area contains parts of three physiographic provinces, the Alaska Range, the Yukon-Tanana Upland, and the Northway-Tanana Lowland. The high, rugged, glaciated landscape of the eastern Alaska Range dominates the southwestern map area. The highest peak, an unnamed summit at the head of Cathedral Rapids Creek No. 2, rises to 2166 m. The gently rolling hills of the Yukon-Tanana Upland, in the northern map area, rise to about 1000 m. The Northway-Tanana Lowland contains the valley of the westerly flowing Tanana River. Elevations along the floor of the lowland generally range between 470 and 520 m. The dominant feature within the map is the Tok fan, which occupies about 20 percent of the map area. This large (450 km2), nearly featureless fan contains a high percentage of volcanic clasts derived from outside the present-day drainage of the Tok River. Because the map area is dominated by various surficial deposits, the map depicts 26 different surficial units consisting of man-made, alluvial, colluvial, eolian, lacustrine, organic, glaciofluvial, glacial, and periglacial deposits. The accompanying table provides information concerning the various units including their properties, characteristics, resource potential, and associated hazards in this area of the upper Tanana valley.

  10. Reducing neonatal infections in south and south central Vietnam: the views of healthcare providers

    PubMed Central

    2013-01-01

    Background Infection causes neonatal mortality in both high and low income countries. While simple interventions to prevent neonatal infection are available, they are often poorly understood and implemented by clinicians. A basic understanding of healthcare providers' perceptions of infection control provides a platform for improving current practices. Our aim was to explore the views of healthcare providers in provincial hospitals in south and south central Vietnam to inform the design of programmes to improve neonatal infection prevention and control. Methods All fifty-four participants who attended a workshop on infection prevention and control were asked to complete an anonymous, written questionnaire identifying their priorities for improving neonatal infection prevention and control in provincial hospitals in south and south central Vietnam. Results Hand washing, exclusive breastfeeding and safe disposal of medical waste were nominated by most participants as priorities for preventing neonatal infections. Education through instructional posters and written guidelines, family contact, kangaroo-mother-care, limitation of invasive procedures and screening for maternal GBS infection were advocated by a smaller proportion of participants. Conclusions The opinions of neonatal healthcare providers at the workshop accurately reflect some of the current international recommendations for infection prevention. However, other important recommendations were not commonly identified by participants and need to be reinforced. Our results will be used to design interventions to improve infection prevention in Vietnam, and may be relevant to other low-resource countries. PMID:23570330

  11. Alaska Glaciers and Rivers

    NASA Technical Reports Server (NTRS)

    2007-01-01

    The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Terra satellite captured this image on October 7, 2007, showing the Alaska Mountains of south-central Alaska already coated with snow. Purple shadows hang in the lee of the peaks, giving the snow-clad land a crumpled appearance. White gives way to brown on the right side of the image where the mountains yield to the lower-elevation Susitna River Valley. The river itself cuts a silver, winding path through deep green forests and brown wetlands and tundra. Extending from the river valley, are smaller rivers that originated in the Alaska Mountains. The source of these rivers is evident in the image. Smooth white tongues of ice extend into the river valleys, the remnants of the glaciers that carved the valleys into the land. Most of the water flowing into the Gulf of Alaska from the Susitna River comes from these mountain glaciers. Glacier melt also feeds glacier lakes, only one of which is large enough to be visible in this image. Immediately left of the Kahiltna River, the aquamarine waters of Chelatna Lake stand out starkly against the brown and white landscape.

  12. Facies comparison of autochthonous and allochthonous Permian and Triassic units, north-central Brooks Range, Alaska

    SciTech Connect

    Adams, K.E.

    1985-04-01

    Eight stratigraphic sections of Permian and Triassic rocks have been studied over a 30 km by 150 km area in the Endicott and Philip Smith Mountains of the central Brooks Range. Six of the sections are located on the Endicott Mountains allochthon, and the remaining two are parautochthonous columns in the Mount Doonerak area. The sections record a facies transition between the autochthonous Sadlerochit Group and Shublik Formation of the northeastern Brooks Range and the characteristically siliceous rocks of the allochthonous Siksikpuk and Otuk formations of the western Brooks Range. Laterally continuous and bioturbated beds of fine-grained sandstone, siltstone, and shale dominantly compose the Permian sequence, whereas the Triassic rocks consist of black shales, thin rhythmically bedded siliceous mudstones, and fossiliferous limestones. When the allochthonous sections are restored to a position south of the Mount Doonerak area, a general shallowing trend from southwest to northwest becomes evident within the reconstructed marine basin. To the south and west, the Permian sediments show a marked increase in silica content, with the occurrence of barite and a corresponding decrease in the thickness of the basal, coarser grained clastics. The Triassic formations also document an increase in silica and the presence of barite to the south and west, while becoming significantly sooty and phosphatic to the north and east. Ongoing petrographic and micropaleontologic studies of the field data will clarify these general paleogeographic relationships.

  13. Hydrogeology of south-central St Croix, US Virgin Islands

    USGS Publications Warehouse

    Graves, R.P.

    1995-01-01

    The subsurface geology of south-central St. Croix consists of alluvium and underlying carbonate rocks. The alluvial deposits consist of sand and gravel with cobbles and boulders and, locally, thin lenses of silt and clay. The carbonate rocks consist of the Oligocene to Middle Miocene age Jealousy formation, the Miocene and Pliocene are Kingshill Limestone, and the Pliocene and younger age Post-Kingshill Carbonates. Ground water occurs under water-table conditions in the alluvial, Post-Kingshill Carbonates, and Kingshill Limestone deposits. These deposits are hydraulically connected and are considered to be a single hydrologic unit. The top of the water-table aquifer can range from 5 to 68 feet below land surface. The top of the Jealousy Formation is considered to be the bottom of the water- table aquifer and generally is from 85 to greater than 120 feet below land surface. Aquifer yields in south- central St. Croix can range from less than 5 gallons per minute to 80 gallons per minute. The ground- water in the study area is of the sodium-chloride type. Ground-water samples collected from selected wells had chloride concentrations ranging from 64 to 4,400 milligrams per liter, and dissolved solid concen- trations ranging from 619 to 7,540 milligrams per liter. Connate water is suspected as being the source of sodium chloride in the ground water.

  14. Understanding Seismotectonic Aspects of Central and South American Subduction Zones

    NASA Astrophysics Data System (ADS)

    Vargas-Jiménez, Carlos A.; Monsalve-Jaramillo, Hugo; Huérfano, Victor

    2004-10-01

    The Circum-Pacific, and particularly the Central and South America, subduction zones are complex structures that are subject to frequent, large-magnitude earthquakes, volcanic activity, tsunamis, and geological hazards. Among these natural hazards, earthquakes produce the most significant social and economic impacts in Latin America, and the subduction zones therefore demand constant vigilance and intensive study. The American continent has witnessed serveral earthquakes that rank among the most destrive in the world. Earthquakes such as the ones that occurred in Colombia-Ecuador [Mw = 8.9, 1906], Chile [Mw = 9.6, 1960; Mw = 8.9, 1995], Mexico [Mw = 9.6, 1985], and Peru [Mw = 8.0, 2001], as well as a number of destuctive events related to crustal fault systems and volcanic eruptions [e.g., Soufrière, El Ruiz, Galeras, ect.], have produced significant human and economic loss.The latent seismic hazards in the Caribbean, and Central and South America demand from the regional Earth sciences community accurate models to explain the mechanisms of these natural phenomena.

  15. Physical Modeling of Hydrologic Processes in South Central Texas

    NASA Astrophysics Data System (ADS)

    El Hassan, A.; Sharif, H.; Xie, H.; Terrance, J.; Mcclelland, J.

    2012-04-01

    Flood magnitude and recurrence modeling and analysis play an important role in water resources planning, management, and permitting. In both urban and rural situations, flood analysis is important to flood plain mapping and the development of best management practices for both environmental and engineering concerns. The majority of annual precipitation in South Texas results from extreme, large storm events, which produce flash floods (the number one cause of weather-related deaths in Texas). Surface geology such as such as Edward out crop faulting zone at Balcones escarpment has different properties than the classified soil; affect the soil parameters such as infiltration or hydraulic conductivity. This result in a very high infiltration and channel loss as a recharge component to the Edward aquifer from the surface runoff and rivers that are crossing the recharge zone, such as Nueces, San Antonio, Guadalupe and Colorado Rivers. Water quality is another issue in hydrological modeling, specifically in south central Texas. Water quality assessment is another issue on hydrological modeling in south central Texas. SWAT Soil and water assessment tool model is used for water quality assessment in San Antonio River basin since the rainfall runoff simulation is a necessity to derive the surface water quality process especially in the streams. With the advances in the Geographical information system (GIS) and instant precipitation products such as next generation radar (NEXRAD) and data acquisition for these products, the accuracy of the hydrological models has improved. Different hydrological models were used to evaluate the surface water and other hydrological cycle components in different watersheds in south central Texas through different events and their different causes and effects in these watersheds. Some of them are semi distributed and lumped models such as Soil and Water Assessment Tool (SWAT), Hydrologic Modeling System (HEC-HMS) and physically based

  16. 77 FR 14006 - Proposed Development of the Alaska Stand Alone Gas Pipeline Project (ASAP), From the North Slope...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-08

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF DEFENSE Department of the Army, Corps of Engineers Proposed Development of the Alaska Stand Alone Gas Pipeline Project (ASAP), From the North Slope to South Central Alaska, Draft Environmental Impact Statement...

  17. New glass sponges (Porifera: Hexactinellida) from deep waters of the central Aleutian Islands, Alaska.

    PubMed

    Reiswig, Henry M; Stone, Robert P

    2013-01-01

    Hexactinellida from deep-water communities of the central Aleutian Islands, Alaska, are described. They were mostly collected by the remotely operated vehicle 'Jason II' from 494–2311 m depths during a 2004 RV 'Roger Revelle' expedition, but one shallow-water species collected with a shrimp trawl from 155 m in the same area is included. The excellent condition of the ROV-collected specimens enabled valuable redescription of some species previously known only from badly damaged specimens. New taxa include one new genus and eight new species in five families. Farreidae consist of two new species, Farrea aleutiana and F. aspondyla. Euretidae consists of only Pinulasma fistulosum n. gen., n. sp. Tretodictyidae include only Tretodictyum amchitkensis n. sp. Euplectellidae consists of only the widespread species Regadrella okinoseana Ijima, reported here over 3,700 km from its closest previously known occurrence. The most diverse family, Rossellidae, consists of Aulosaccus ijimai (Schulze), Aulosaccus schulzei Ijima, Bathydorus sp. (young stage not determinable to species), Caulophacus (Caulophacus) adakensis n. sp., Acanthascus koltuni n. sp., Staurocalyptus psilosus n. sp., Staurocalyptus tylotus n. sp. and Rhabdocalyptus mirabilis Schulze. We present argument for reinstatement of the abolished rossellid subfamily Acanthascinae and return of the subgenera  Staurocalyptus Ijima and Rhabdocalyptus Schulze to their previous generic status. These fauna provides important complexity to the hard substrate communities that likely serve as nursery areas for the young stages of commercially important fish and crab species, refuge from predation for both young and adult stages, and also as a focal source of prey for juvenile and adult stages of those same species.

  18. Preliminary volcano-hazard assessment for Akutan Volcano east-central Aleutian Islands, Alaska

    USGS Publications Warehouse

    Waythomas, Christopher F.; Power, John A.; Richter, Donlad H.; McGimsey, Robert G.

    1998-01-01

    Akutan Volcano is a 1100-meter-high stratovolcano on Akutan Island in the east-central Aleutian Islands of southwestern Alaska. The volcano is located about 1238 kilometers southwest of Anchorage and about 56 kilometers east of Dutch Harbor/Unalaska. Eruptive activity has occurred at least 27 times since historical observations were recorded beginning in the late 1700?s. Recent eruptions produced only small amounts of fine volcanic ash that fell primarily on the upper flanks of the volcano. Small amounts of ash fell on the Akutan Harbor area during eruptions in 1911, 1948, 1987, and 1989. Plumes of volcanic ash are the primary hazard associated with eruptions of Akutan Volcano and are a major hazard to all aircraft using the airfield at Dutch Harbor or approaching Akutan Island. Eruptions similar to historical Akutan eruptions should be anticipated in the future. Although unlikely, eruptions larger than those of historical time could generate significant amounts of volcanic ash, fallout, pyroclastic flows, and lahars that would be hazardous to life and property on all sectors of the volcano and other parts of the island, but especially in the major valleys that head on the volcano flanks. During a large eruption an ash cloud could be produced that may be hazardous to aircraft using the airfield at Cold Bay and the airspace downwind from the volcano. In the event of a large eruption, volcanic ash fallout could be relatively thick over parts of Akutan Island and volcanic bombs could strike areas more than 10 kilometers from the volcano.

  19. Paleoseismology of the Denali fault system at the Schist Creek site, central Alaska

    USGS Publications Warehouse

    Personius, Stephen F.; Crone, Anthony J.; Burns, Patricia A.C.; Rozell, Ned

    2016-01-06

    Two hand-dug trenches at the Schist Creek site on the Denali fault system in central Alaska exposed evidence of four surface-rupturing earthquakes on the basis of upward terminations of fault strands and at least one buried, scarp-derived colluvial wedge. Limited radiocarbon ages provide some constraints on times of the ruptures. The youngest rupture (PE1) likely occurred about 200–400 years ago, the penultimate rupture (PE2) is younger than 1,200 years old, the third event back (PE3) occurred between 1,200 and 2,700 years ago, and the oldest rupture (PE4) occurred more than 2,700 and less than 17,000 years ago. Evidence for a possible additional rupture (PE4?) is equivocal and probably is related to earthquake PE4. On the basis of a nearby measured slip rate of 9.4 ± 1.6 millimeters per year and the long interevent times between our documented ruptures, we believe that our paleoseismic record at this site is incomplete. We suspect one undocumented earthquake between PE1 and PE2 and one or perhaps two more earthquakes between PE2 and PE3. We found stratigraphic evidence in the trenches for only four or possibly five (PE4?) earthquakes, but the addition of two or three inferred earthquakes yields a record of eight possible surface ruptures at the Schist Creek site. Our interpretation of the paleoseismic history at the site is consistent with recurrence intervals of several hundred years on this section of the Denali fault system.

  20. Holocene pollen and sediment record from the tangle lakes area, central Alaska

    USGS Publications Warehouse

    Ager, Thomas A.; Sims, John D.

    1981-01-01

    Pollen and sediments have been analyzed from a 5.5 meter‐length core of lacustrine sediments from Tangle Lakes, in the Gulkana Upland south of the Alaska Range (63 ° 01 ‘ 46”; N. latitude, 146° 03 ‘ 48 “ W. longitude). Radiocarbon ages indicate that the core spans the last 4700 years. The core sediments are sandy silt and silty clay; the core shows distinct rhythmic laminations in the lower 398 cm. The laminae appear to be normally graded; peat fibers and macerated plant debris are more abundant near the tops of the laminae. Six volcanic‐ash layers are present in the upper 110 cm of the core.Present‐day vegetation of the Tangle Lakes area is mesic shrub tundra and open spruce woodland, with scattered patches of shrub willow (Salix), balsam poplar (P. balsamifera), spruce (Picea), paper birch (Betula papyrifera), and alder (Alnus). Pollen analysis of 27 core samples suggests that this vegetation type has persisted throughout the past 4700 years, except for an apparently substantial increase in Picea beginning about 3500 years B.P. Percentages of Picea pollen are very low (generally 1–3 percent) in the lower 2 meters of core (ca. 4700 to 3500 years B.P.), but rise to 13–18 percent in the upper 3.4 meters (ca. 3500 years B.P. to present). Previously reported data from this area indicate that Picea trees initially arrived in the Tangle Lakes area about 9100 years B.P., at least 2.5 to 3 thousand years after deglaciation of the region. The present investigation suggests that Picea trees became locally scarce or died out sometime after about 9000 years B.P. but before 4700 years B.P., then reinvaded the area about 3500 years B.P. If this extrapolated age for the Picea reinvasion is accurate it suggests that local expansion of the Picea population coincides with the onset of a Neoglacial interval of cooler, moister climate. This is an unexpected result, because intervals of cooler climate generally coincide with lowering of the altitudinal limit of

  1. Mesozoic and Cenozoic tectonics of the eastern and central Alaska Range: Progressive basin development and deformation in a suture zone

    USGS Publications Warehouse

    Ridgway, K.D.; Trop, J.M.; Nokleberg, W.J.; Davidson, C.M.; Eastham, K.R.

    2002-01-01

    Analysis of late Mesozoic and Cenozoic sedimentary basins, metamorphic rocks, and major faults in the eastern and central Alaska Range documents the progressive development of a suture zone that formed as a result of collision of an island-arc assemblage (the Wrangellia composite terrane) with the former North American continental margin. New basin-analysis, structural, and geochronologic data indicate the following stages in the development of the suture zone: (1) Deposition of 3-5 km of Upper Jurassic-Upper Cretaceous marine strata (the Kahiltna assemblage) recorded the initial collision of the island-arc assemblage with the continental margin. The Kahiltna assemblage exposed in the northern Talkeetna Mountains represents a Kimmeridgian-Valanginian backarc basin that was filled by northwestward-flowing submarine-fan systems that were transporting sediment derived from Mesozoic strata of the island-arc assemblage. The Kahiltna assemblage exposed in the southern Alaska Range represents a Valanginian-Cenomanian remnant ocean basin filled by west-southwestward-flowing submarine-fan systems that were transporting sediment derived from Paleozoic continental-margin strata uplifted in the along-strike suture zone. A belt of retrograde metamorphism and a regional anticlinorium developed along the continental margin from 115 to 106 Ma, roughly coeval with the end of widespread deposition in the Kahiltna sedimentary basins. (2) Metamorphism of submarine-fan deposits of the Kahiltna basin, located near the leading edge of the island-arc assemblage, occurred at ca. 74 Ma, as determined from a new U-Pb zircon age for a synkinematic sill. Coeval with metamorphism of deposits of the Kahiltna basin in the southern part of the suture zone was development of a thrust-top basin, the Cantwell basin, in the northern part of the suture zone. Geologic mapping and compositional data suggest that the 4 km of Upper Cretaceous nonmarine and marginal marine sedimentary strata in this basin

  2. Geologic and isostatic map of the Nenana Basin area, central Alaska

    USGS Publications Warehouse

    Frost, G.M.; Barnes, D.F.; Stanley, R.G.

    2002-01-01

    Introduction The Nenana Basin area is a prospective petroleum province in central Alaska, and this geologic and isostatic gravity map is part of a petroleum resource assessment of the area. The geology was compiled from published sources (Chapman and others, 1971, 1975a, 1975b, 1982; Chapman and Yeend, 1981; Csejtey and others, 1986; Jones and others, 1983; Pewe and others, 1966; Reed, 1961; and Weber and others, 1992), as shown on the index map (map sheet). Map units are organized and presented according to the scheme of lithotectonic terranes proposed by Jones and others (1987) and Silberling and Jones (1984); we recognize, however, that this terrane scheme is controversial and likely to be revised in the future. In some cases, we combined certain terranes because we were unable to match the terrane boundaries given by Jones and others (1987) and Silberling and Jones (1984) with specific faults shown on existing geologic maps. Postaccretion cover deposits represent overlap assemblages that depositionally overlie accreted terranes. Plutonic igneous rocks shown on this map include several plutons that are clearly postaccretionary, based on isotopic ages and (or) field relations. It is possible that some of the plutons predate accretion, but this has not been demonstrated. According to Jones and others (1982), the terranes in the area of our map were assembled during late Mesozoic or earliest Cenozoic time. The gravity contours are derived from data used in earlier compilations (Barnes, 1961, 1977; Hackett, 1981; Valin and others, 1991; Frost and Stanley, 1991) that are supplemented by some National Oceanic and Atmospheric Administration data along the Alaska Pipeline level line (W.E. Strange, written commun., 1980). The earlier compilations were used for simple Bouguer maps, prepared primarily by non-digital methods, and are superseded by this map. The present map is the result of digital processing that includes the 1967 Geodetic Reference System, the IGSN-71

  3. Geologic map of the Kechumstuk fault zone in the Mount Veta area, Fortymile mining district, east-central Alaska

    USGS Publications Warehouse

    Day, Warren C.; O’Neill, J. Michael; Dusel-Bacon, Cynthia; Aleinikoff, John N.; Siron, Christopher R.

    2014-01-01

    This map was developed by the U.S. Geological Survey Mineral Resources Program to depict the fundamental geologic features for the western part of the Fortymile mining district of east-central Alaska, and to delineate the location of known bedrock mineral prospects and their relationship to rock types and structural features. This geospatial map database presents a 1:63,360-scale geologic map for the Kechumstuk fault zone and surrounding area, which lies 55 km northwest of Chicken, Alaska. The Kechumstuk fault zone is a northeast-trending zone of faults that transects the crystalline basement rocks of the Yukon-Tanana Upland of the western part of the Fortymile mining district. The crystalline basement rocks include Paleozoic metasedimentary and metaigneous rocks as well as granitoid intrusions of Triassic, Jurassic, and Cretaceous age. The geologic units represented by polygons in this dataset are based on new geologic mapping and geochronological data coupled with an interpretation of regional and new geophysical data collected by the Alaska Department of Natural Resources, Division of Geological and Geophysical Surveys. The geochronological data are reported in the accompanying geologic map text and represent new U-Pb dates on zircons collected from the igneous and metaigneous units within the map area.

  4. Biogeochemical characterization of an undisturbed highly acidic, metal-rich bryophyte habitat, east-central Alaska, U.S.A.

    USGS Publications Warehouse

    Gough, L.P.; Eppinger, R.G.; Briggs, P.H.; Giles, S.

    2006-01-01

    We report on the geochemistry of soil and bryophyte-laden sediment and on the biogeochemistry of willows growing in an undisturbed volcanogenic massive sulfide deposit in the Alaska Range ecoregion of east-central Alaska. We also describe an unusual bryophyte assemblage found growing in the acidic metal-rich waters that drain the area. Ferricrete-cemented silty alluvial sediments within seeps and streams are covered with the liverwort Gymnocolea inflata whereas the mosses Polytrichum commune and P. juniperinum inhabit the area adjacent to the water and within the splash zone. Both the liverwort-encrusted sediment and Polytrichum thalli have high concentrations of major and trace metal cations (e.g., Al, As, Cu, Fe, Hg, La, Mn, Pb, and Zn). Soils in the area do not reflect the geochemical signature of the mineral deposit and we postulate they are influenced by the chemistry of eolian sediments derived from outside the deposit area. The willow, Salix pulchra, growing mostly within and adjacent to the larger streams, has much higher concentrations of Al, As, Cd, Cr, Fe, La, Pb, and Zn when compared to the same species collected in non-mineralized areas of Alaska. The Cd levels are especially high and are shown to exceed, by an order of magnitude, levels demonstrated to be toxic to ptarmigan in Colorado. Willow, growing in this naturally occurring metal-rich Red Mountain alteration zone, may adversely affect the health of browsing animals. ?? 2006 Regents of the University of Colorado.

  5. Late quaternary vegetation development in south-central Illinois

    USGS Publications Warehouse

    Gruger, E.

    1972-01-01

    Pollen and macrofossil evidence for the nature of the vegetation during glacial and interglacial periods in the regions south of the Wisconsinan ice margin is still very scarce. Modern opinions concerning these problems are therefore predominantly derived from geological evidence only or are extrapolated from pollen studies of late Wisconsinan deposits. Now for the first time pollen and macrofossil analyses are available from south-central Illinois covering the Holocene, the entire Wisconsinan, and most probably also Sangamonian and late Illinoian time. The cores studied came from three lakes, which originated as kettle holes in glacial drift of Illinoian age near Vandalia, Fayette County. The Wisconsinan ice sheet approached the sites from the the north to within about 60 km distance only. One of the profiles (Pittsburg Basin) probably reaches back to the late Illinoian (zone 1), which was characterized by forests with much Picea. Zone 2, most likely of Sangamonian age, represents a period of species-rich deciduous forests, which must have been similar to the ones that thrive today south and southeast of the prairie peninsula. During the entire Wisconsinan (14C dates ranging from 38,000 to 21,000 BP) thermophilous deciduous trees like Quercus, Carya, and Ulmus occurred in the region, although temporarily accompanied by tree genera with a more northerly modern distribution, such as Picea, which entered and then left south-central Illinois during the Woodfordian. Thus it is evident that arctic climatic conditions did not prevail in the lowlands of south-central Illinois (about 38??30??? lat) during the Wisconsinan, even at the time of the maximum glaciation, the Woodfordian. The Wisconsinan was, however, not a period of continuous forest. The pollen assemblages of zone 3 (Altonian) indicate prairie with stands of trees, and in zone 4 the relatively abundant Artemisia pollen indicates the existence of open vegetation and stands of deciduous trees, Picea, and Pinus

  6. Chemical characteristics of south-central Lake Huron

    USGS Publications Warehouse

    Allen, Herbert E.

    1964-01-01

    Water samples were collected for chemical analysis during eight cruises of the U.S. Bureau of Commercial Fisheries M/V CISCO in south-central Lake Huron in June-October 1956. Temperature, pH, conductivity, and the concentrations of Na+, K+, Ca++, C1-, SO4-, SiO2, and dissolved oxygen were determined for 233 samples from stations at the mouth of Saginaw Bay and along a transect from Harbor Beach, Michigan, to Goderich, Ontario. The chemical compostion, with the exception of silica, did not vary with season or depth. Water flowing into the lake from Saginaw Bay sometimes caused marked increases in the concentration of chemicals in surface samples at certain stations. Prevailing currents determined the location of these areas of higher salt concentration.

  7. Global GIS database; digital atlas of Central and South America

    USGS Publications Warehouse

    Hearn,, Paul P.; Hare, T.; Schruben, P.; Sherrill, D.; LaMar, C.; Tsushima, P.

    2000-01-01

    This CD-ROM contains a digital atlas of the countries of Central and South America. This atlas is part of a global database compiled from USGS and other data sources at the nominal scale of 1:1 million and is intended to be used as a regional-scale reference and analytical tool by government officials, researchers, the private sector, and the general public. The atlas includes free GIS software or may also be used with ESRI's ArcView software. Customized ArcView tools, specifically designed to make the atlas easier to use, are also included. The atlas contains the following datasets: country political boundaries, digital shaded relief map, elevation, slope, hydrology, locations of cities and towns, airfields, roads, railroads, utility lines, population density, geology, ecological regions, historical seismicity, volcanoes, ore deposits, oil and gas fields, climate data, landcover, vegetation index, and lights at night.

  8. The south-central United States magnetic anomaly

    NASA Technical Reports Server (NTRS)

    Hinze, W. J.; Braile, L. W. (Principal Investigator); Starich, P. J.

    1984-01-01

    The South-Central United States Magnetic Anomaly is the most prominent positive feature in the MAGSAT scalar magnetic field over North America. The anomaly correlates with increased crustal thickness, above average crustal velocity, negative free air gravity anomalies and an extensive zone of Middle Proterozoic anorogenic felsic basement rocks. Spherical dipole source inversion of the MAGSAT scalar data and subsequent calculation of reduced to pole and derivative maps provide constraints for a crustal magnetic model which corresponds geographically to the extensive Middle Proterozoic felsic rocks trending northeasterly across the United States. These felsic rocks contain insufficient magnetization or volume to produce the anomaly, but are rather indicative of a crustal zone which was disturbed during a Middle Proterozoic thermal event which enriched magnetic material deep in the crust.

  9. Wind energy resource atlas. Volume 7. The south central region

    SciTech Connect

    Edwards, R.L.; Graves, L.F.; Sprankle, A.C.; Elliott, D.L.; Barchet, W.R.; George, R.L.

    1981-03-01

    This atlas of the south central region combines seven collections of wind resource data: one for the region, and one for each of the six states (Arkansas, Kansas, Louisiana, Missouri, Oklahoma, and Texas). At the state level, features of the climate, topography, and wind resource are discussed in greater detail than that provided in the regional discussion, and the data locations on which the assessment is based are mapped. Variations, over several time scales, in the wind resource at selected stations in each state are shown on graphs of monthly average and interannual wind speed and power, and hourly average wind speed for each season. Other graphs present speed, direction, and duration frequencies of the wind at these locations.

  10. Natural phenomena hazards, Hanford Site, south central Washington

    SciTech Connect

    Tallman, A.M.

    1996-04-16

    This document presents the natural phenomena hazard (NPH) loads for use in implementing DOE Order 5480.28, Natural Phenomena Hazards Mitigation, at the Hanford Site in south-central Washington State. The purpose of this document is twofold: (1) summarize the NPH that are important to the design and evaluation of structures, systems, and components at the Hanford Site; (2) develop the appropriate natural phenomena loads for use in the implementation of DOE Order 5480.28. The supporting standards, DOE-STD-1020-94, Natural Phenomena Hazards Design and Evaluation Criteria for Department of Energy Facilities (DOE 1994a); DOE-STD-1022-94, Natural Phenomena Hazards Site Characteristics Criteria (DOE 1994b); and DOE-STD-1023-95, Natural Phenomena Hazards Assessment Criteria (DOE 1995) are the basis for developing the NPH loads.

  11. Airborne electromagnetic and magnetic geophysical survey data of the Yukon Flats and Fort Wainwright areas, central Alaska, June 2010

    USGS Publications Warehouse

    Ball, Lyndsay B.; Smith, Bruce D.; Minsley, Burke J.; Abraham, Jared D.; Voss, Clifford I.; Astley, Beth N.; Deszcz-Pan, Maria; Cannia, James C.

    2011-01-01

    In June 2010, the U.S. Geological Survey conducted airborne electromagnetic and magnetic surveys of the Yukon Flats and Fort Wainwright study areas in central Alaska. These data were collected to estimate the three-dimensional distribution of permafrost at the time of the survey. These data were also collected to evaluate the effectiveness of these geophysical methods at mapping permafrost geometry and to better define the physical properties of the subsurface in discontinuous permafrost areas. This report releases digital data associated with these surveys. Inverted resistivity depth sections are also provided in this data release, and data processing and inversion methods are discussed.

  12. The Middle Fork Plutonic Complex: A plutonic association of coeval peralkaline and metaluminous magmas in the north-central Alaska Range

    SciTech Connect

    Solie, D.N.

    1988-01-01

    The 57 m.y. Middle Fork Plutonic Complex (MFPC) intrudes Paleozoic metasedimentary rocks south of the Farewell Fault zone in the north-central Alaska Range. Though spatially related to the late Cretaceous - Early Tertiary subduction-related Alaska Range batholith, MFPC is more characteristic of an extensional or anorogenic setting. A swarm of basalt, hawaiite and rhyolite dikes east of the complex intruded, and was intruded by, the plutonic rocks. Approximately 30% of the exposed rock in the 125 km[sup 2] complex is hedenbergite - fayalite syenite, [approx equal]20% is peralkalin arfvedsonite-biotite alkali-feldspar granite (AF granite), and [le]20% is pyroxene-olivine-biotite gabbro. The rest is a mixed unit including clinopyroxene-biotite-amphibole diorite, and hornblende-biotite granite (HB granite). K-Ar and Rb-Sr radiometric dating of rock types shows that they are coeval. Their close spatial and temporal relationships led to complex magmatic interactions. Calculated initial [sup 87]Sr/[sup 86]Sr for gabbro and diorite group is around 0.705 to 0.706. HB granites are heterogeneous, but fall mostly around 0.707 to 0.708. Hypersolvus syenites and AF granites form an isochron with initial [sup 87]Sr/[sup 86]Sr of 0.70965. These groupings suggest that at least three different magmas formed the MFPC; scatter of isotopic data reflects mutual contamination and assimilation. Consanguinous hypersolvus syenite and AF granite mineralogy appears to be controlled by fluorine in the magma chamber. Eruptive stratigraphy, as predicted by intrusive history of MFPC, compares favorably with volcanic stratigraphies of peralkaline volcanic systems worldwide, and MFPC may be modelled as the root zone of a peralkaline volcanic system.

  13. 2009 Volcanic activity in Alaska, Kamchatka, and the Kurile Islands: summary of events and response of the Alaska Volcano Observatory

    USGS Publications Warehouse

    McGimsey, Robert G.; Neal, Christina A.; Girina, Olga A.; Chibisova, Marina; Rybin, Alexander

    2014-01-01

    The Alaska Volcano Observatory (AVO) responded to eruptions, possible eruptions, volcanic unrest, and reports of unusual activity at or near eight separate volcanic centers in Alaska during 2009. The year was highlighted by the eruption of Redoubt Volcano, one of three active volcanoes on the western side of Cook Inlet and near south-central Alaska's population and commerce centers, which comprise about 62 percent of the State's population of 710,213 (2010 census). AVO staff also participated in hazard communication and monitoring of multiple eruptions at ten volcanoes in Russia as part of its collaborative role in the Kamchatka and Sakhalin Volcanic Eruption Response Teams.

  14. Cultural remains in local and regional context on the central Alaska Peninsula: housepits, language, and cultural affinities at Marraatuq after 1000 B.P.

    PubMed

    McClenahan, Patricia L

    2010-01-01

    Professor Dumond's research on the Alaska Peninsula provided information that prior to 1,000 years ago people of both sides of the Alaska Peninsula shared material culture and exhibited subsistence interests that persisted into historic times, During the Late Precontact Era (ca. 1100 A.D. to mid-1700s) these Alutiiq societies shared cultural traits including language, house styles, and material culture with their relatives and neighbors on Kodiak Island. Until recently, few data were available regarding potential variability in house construction techniques, or styles and functions of Alutiiq semi-subterranean houses of this era found on the Alaska Peninsula, This paper provides examples of a few known prehistoric and historic Alaska Peninsula and Kodiak Alutiiq houses and presents previously unreported data from archaeological tests at Marraatuq on the Central Alaska Peninsula, Taken together with Dumond's 1998-1999 field work at Leader Creek and archaeological research on Kodiak Island, the work provides further evidence that interregional interaction was strong during the Late Precontact Era. However, large population centers and ranked political hierarchies probably were not hallmarks of central Alaska Peninsula communities during the Late Precontact Era and historic times as they were on the Kodiak and Aleutian islands.

  15. The diorite at West Warren, south-central Massachusetts

    USGS Publications Warehouse

    Pomeroy, John S.

    1974-01-01

    Follated, syntectonic, concordant intrusive bodies of mostly diorite and meladiorite with less abundant quartz diorite and norite have been mapped in the West Warren area of south-central Massachusetts. The rocks of the pluton range from a medium colored phase of diorite and quartz diorite to a dark colored phase of meladiorite and norite. Major minerals In the dioritic rocks are calcic andesine, green hornblende, brown biotite, and hypersthene. Igneous textures are dominant, and retrograde or deuteric effects are generally minor. Silica and alumina contents of the dioritic rocks are somewhat higher than for average diorites; conversely, the oxides of iron, magnesium, and calcium are generally lower. Normative quartz, albite, and anorthite are higher and orthoclase is lower in the samples than In the average diorite. Sizeable plutons of diorite-norite are uncommon in central Massachusetts. The West Warren body, roughly 26 km2 (10 square miles) in area, bears little petrochemical relation to adjacent rock units. The pluton can be construed as belonging to a belt of intrusive mafic rocks which stretches from southeastern New York to coastal Maine.

  16. Structural evolution of an arc-basin: The Gravina Belt in central southeastern Alaska

    USGS Publications Warehouse

    Haeussler, Peter J.

    1992-01-01

    The upper Middle Jurassic-Lower Cretaceous Gravina belt lies along the eastern margin of the Alexander terrane in southeastern Alaska. This group of turbidites and mafic to intermediate volcanic rocks was deformed during mid to Late Cretaceous time during the closing of a basin of unknown size between the Alexander terrane on the west and the Stikine terrane to the east. Therefore structures of Gravina belt rocks largely reflect the final accretion and subsequent transport of the Alexander terrane. Six geologic transects across the central Gravina belt (southern Mitkof Island to northern Douglas Island) define a structural history that includes (1) syndepositional soft-sediment folding and faulting, possibly in conjunction with block tilting and extension; (2) tight to isoclinal folding or thrust faulting, with formation of a slaty cleavage (S1) striking ∼330°; (3) local coaxial refolding with formation of crenulation cleavage (S2); (4) development of domainal crenulation folds and cleavage (S3) oriented at a large angle to the margin of the belt; (5) intrusion of tonalitic plutons around 90 Ma; and (6) right-lateral strike-slip displacement on faults oriented ∼330°. Finite strain measurements on sedimentary rocks suggest the belt was at least twice its present width, normal to the foliation, before deformation. Subhorizontal margin-parallel fold axes, margin-parallel slaty cleavage, and margin-perpendicular stretching lineations suggest orthogonal contraction of the Gravina basin, assuming that oblique plate convergence was not decoupled along strike-slip faults. After contractional deformation, strike-slip faults indicate dextral displacement (probably of the order of several tens of kilometers) of the Alexander terrane with respect to the terranes to the east. Domainal crenulation folds and cleavages at a high angle to the margin of the belt suggest that the change in convergence directions occurred while the rocks (presently at the surface) could still

  17. Late Quaternary vegetation and climate history of the central Bering land bridge from St. Michael Island, western Alaska

    USGS Publications Warehouse

    Ager, T.A.

    2003-01-01

    Pollen analysis of a sediment core from Zagoskin Lake on St. Michael Island, northeast Bering Sea, provides a history of vegetation and climate for the central Bering land bridge and adjacent western Alaska for the past ???30,000 14C yr B.P. During the late middle Wisconsin interstadial (???30,000-26,000 14C yr B.P.) vegetation was dominated by graminoid-herb tundra with willows (Salix) and minor dwarf birch (Betula nana) and Ericales. During the late Wisconsin glacial interval (26,000-15,000 14C yr B.P.) vegetation was graminoid-herb tundra with willows, but with fewer dwarf birch and Ericales, and more herb types associated with dry habitats and disturbed soils. Grasses (Poaceae) dominated during the peak of this glacial interval. Graminoid-herb tundra suggests that central Beringia had a cold, arid climate from ???30,000 to 15,000 14C yr B.P. Between 15,000 and 13,000 14C yr B.P., birch shrub-Ericales-sedge-moss tundra began to spread rapidly across the land bridge and Alaska. This major vegetation change suggests moister, warmer summer climates and deeper winter snows. A brief invasion of Populus (poplar, aspen) occurred ca. 11,000-9500 14C yr B.P., overlapping with the Younger Dryas interval of dry, cooler(?) climate. During the latest Wisconsin to middle Holocene the Bering land bridge was flooded by rising seas. Alder shrubs (Alnus crispa) colonized the St. Michael Island area ca. 8000 14C yr B.P. Boreal forests dominated by spruce (Picea) spread from interior Alaska into the eastern Norton Sound area in middle Holocene time, but have not spread as far west as St. Michael Island. ?? 2003 University of Washington. Published by Elsevier Inc. All rights reserved.

  18. Late Quaternary vegetation and climate history of the central Bering land bridge from St. Michael Island, western Alaska

    NASA Astrophysics Data System (ADS)

    Ager, Thomas A.

    2003-07-01

    Pollen analysis of a sediment core from Zagoskin Lake on St. Michael Island, northeast Bering Sea, provides a history of vegetation and climate for the central Bering land bridge and adjacent western Alaska for the past ≥30,000 14C yr B.P. During the late middle Wisconsin interstadial (≥30,000-26,000 14C yr B.P.) vegetation was dominated by graminoid-herb tundra with willows ( Salix) and minor dwarf birch ( Betula nana) and Ericales. During the late Wisconsin glacial interval (26,000-15,000 14C yr B.P.) vegetation was graminoid-herb tundra with willows, but with fewer dwarf birch and Ericales, and more herb types associated with dry habitats and disturbed soils. Grasses (Poaceae) dominated during the peak of this glacial interval. Graminoid-herb tundra suggests that central Beringia had a cold, arid climate from ≥30,000 to 15,000 14C yr B.P. Between 15,000 and 13,000 14C yr B.P., birch shrub-Ericales-sedge-moss tundra began to spread rapidly across the land bridge and Alaska. This major vegetation change suggests moister, warmer summer climates and deeper winter snows. A brief invasion of Populus (poplar, aspen) occurred ca.11,000-9500 14C yr B.P., overlapping with the Younger Dryas interval of dry, cooler(?) climate. During the latest Wisconsin to middle Holocene the Bering land bridge was flooded by rising seas. Alder shrubs ( Alnus crispa) colonized the St. Michael Island area ca. 8000 14C yr B.P. Boreal forests dominated by spruce ( Picea) spread from interior Alaska into the eastern Norton Sound area in middle Holocene time, but have not spread as far west as St. Michael Island.

  19. Challenges Facing Managers in Managing Conflict in Schools in the South and South Central Regions of Botswana

    ERIC Educational Resources Information Center

    Morake, Nnior Machomi; Monobe, Ratau John; Dingwe, Stephonia

    2011-01-01

    The purpose of this study was to examine the challenges facing managers in managing conflict in schools of South and South Central Regions of Botswana. In this study, the schedule of interview was used to collect empirical data. A random sample of 50 school managers and deputy school managers was selected for interviews. Major findings of the…

  20. Subsistence and Settlement at Rathbun Reservoir Area in South Central Iowa

    DTIC Science & Technology

    1988-01-01

    paleolithic of south central Europe. Paper presented at the 42nd annual Society for American Archaeology meetings, New Orleans, LA. 1978 Variability in the...Early Upper Paleolithic of South Central Europe. Ph.D. Dissertation, Department of Anthropology, University of Kansas, Lawrence. Brown, Lionel A. 1965

  1. 7 CFR 319.56-25 - Papayas from Central America and South America.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 5 2014-01-01 2014-01-01 false Papayas from Central America and South America. 319.56... Vegetables § 319.56-25 Papayas from Central America and South America. Commercial consignments of the Solo type of papaya may be imported into the United States only in accordance with this section and...

  2. 7 CFR 319.56-25 - Papayas from Central America and South America.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 5 2013-01-01 2013-01-01 false Papayas from Central America and South America. 319.56... Vegetables § 319.56-25 Papayas from Central America and South America. Commercial consignments of the Solo type of papaya may be imported into the United States only in accordance with this section and...

  3. 7 CFR 319.56-25 - Papayas from Central America and South America.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 5 2011-01-01 2011-01-01 false Papayas from Central America and South America. 319.56... Vegetables § 319.56-25 Papayas from Central America and South America. Commercial consignments of the Solo type of papaya may be imported into the United States only in accordance with this section and...

  4. 7 CFR 319.56-25 - Papayas from Central America and South America.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 5 2012-01-01 2012-01-01 false Papayas from Central America and South America. 319.56... Vegetables § 319.56-25 Papayas from Central America and South America. Commercial consignments of the Solo type of papaya may be imported into the United States only in accordance with this section and...

  5. Baseline channel morphology and bank erosion inventory of South Fork Campbell Creek at Campbell Tract, Anchorage, Alaska, 1999 and 2000

    USGS Publications Warehouse

    Curran, Janet H.

    2001-01-01

    South Fork Campbell Creek drains largely undeveloped land in Anchorage, Alaska, but supports heavy use near the Bureau of Land Management (BLM) Campbell Tract facility for recreation and environmental education. To help assess the impacts of human activities in the basin on biological communities, particularly aquatic and terrestrial biota, morphological changes to the channel bed and banks were monitored for 2 years. Erosion conditions and rates of change were measured and 11 transects were surveyed in three reaches of Campbell Creek near the BLM Campbell Creek Science Center in 1999. Repeat measurements at these 33 transects in 2000 documented noticeable differences between horizontal or vertical channel position at eight transects. Repeat measurements of 51 erosion pins at the survey transects provided details of bank erosion between the 2 years. Annual erosion rates at the erosion pins ranged from 0.81 foot per year of erosion to 0.16 foot per year of deposition.

  6. Distribution and characteristics of metamorphic belts in the south- eastern Alaska part of the North American Cordillera

    USGS Publications Warehouse

    Brew, D.A.; Himmelberg, G.R.; Loney, R.A.; Ford, A.B.

    1992-01-01

    The Cordilleran orogen in south-eastern Alaska includes 14 distinct metamorphic belts that make up three major metamorphic complexes, from east to west: the Coast plutonic-metamorphic complex; the Glacier Bay-Chichagof plutonic-metamorphic complex; and the Chugach plutonic-metamorphic complex. Each of these complexes is related to a major subduction event. The metamorphic history of the Coast complex is lengthy and is related to the Late Cretaceous collision of the Alexander and Wrangellia terranes and the Gravina overlap assemblage to the west against the Stikine terrane to the east. The metamorphic history of the Glacier Bay-Chichagof complex is relatively simple and is related to the roots of a Late Jurassic to late Early Cretaceous island arc. The metamorphic history of the Chugach is complicated and developed during and after the Late Cretaceous collision of the Chugach terrane with the Wrangellia and Alexander terranes. -from Authors

  7. Ground-water investigation at the alluvial fan of the South Fork River, Anchorage, Alaska: results of test drilling, 1976

    USGS Publications Warehouse

    Dearborn, Larry L.

    1977-01-01

    In late 1976, at Anchorage, Alaska, a ground-water exploration well was drilled to a depth of 487 feet on the South Fork Eagle River fan near the confluence with the mainstream. The well penetrated four sand and gravel strata of low water-yielding capacity and extended 37 ft into metamorphic bedrock. Earth water-bearing stratum was pumped for several hours, and the best aquifer yield was found to be 1.7 gal/min/ft of drawdown. These test results support the conclusion, previously inferred from drilling data at a nearby test hole drilled in 1973, that there are no confined aquifers of large yield in the subsurface at this locality. (Woodard-USGS)

  8. Seasonal and Latitudinal Variations in Dissolved Methane from 42 Lakes along a North-South Transect in Alaska

    NASA Astrophysics Data System (ADS)

    Sepulveda-Jauregui, A.; Walter Anthony, K. M.; Martinez-Cruz, K. C.; Anthony, P.; Thalasso, F.

    2013-12-01

    Armando Sepulveda-Jauregui,* Katey M. Walter Anthony,* Karla Martinez-Cruz,* ** Peter Anthony,* and Frederic Thalasso**. * Water and Environmental Research Center, Institute of Northern Engineering, University of Alaska Fairbanks, Fairbanks, Alaska. ** Biotechnology and Bioengineering Department, Cinvestav, Mexico city, D. F., Mexico. Northern lakes are important reservoirs and sources to the atmosphere of methane (CH4), a potent greenhouse gas. It is estimated that northern lakes (> 55 °N) contribute about 20% of the total global lake methane emissions, and that emissions from these lakes will increase with climate warming. Temperature rise enhances methane production directly by providing the kinetic energy to methanogenesis, and indirectly by supplying organic matter from thawing permafrost. Warmer lakes also store less methane since methane's solubility is inversely related to temperature. Alaskan lakes are located in three well-differentiated permafrost classes: yedoma permafrost with high labile carbon stocks, non-yedoma permafrost with lower carbon stocks, and areas without permafrost, also with generally lower carbon stocks. We sampled dissolved methane from 42 Alaskan lakes located in these permafrost cover classes along a north-south Alaska transect from Prudhoe Bay to the Kenai Peninsula during open-water conditions in summer 2011. We sampled 26 of these lakes in April, toward the end of the winter ice-covered period. Our results indicated that the largest dissolved methane concentrations occurred in interior Alaska thermokarst lakes formed in yedoma-type permafrost during winter and summer, with maximal concentrations of 17.19 and 12.76 mg L-1 respectively. In these lakes, emission of dissolved gases as diffusion during summer and storage release in spring were 18.4% and 17.4% of the annual emission budget, while ebullition (64.2 %) comprised the rest. Dissolved oxygen was inversely correlated with dissolved methane concentrations in both seasons; the

  9. Sedimentology and stratigraphy of the Kanayut Conglomerate, central Brooks Range, Alaska; report of 1980 field season

    USGS Publications Warehouse

    Nilsen, T.H.; Moore, T.E.; Balin, D.F.; Johnson, S.Y.

    1982-01-01

    The Upper Devonian Kanayut Conglomerate crops out along the crest of the Brooks Range of northern Alaska for a distance of almost 1000 km. It ranges in thickness from 2600 m in the Atigun River area to 700 m south of Anaktuvuk Pass and has been subdivided into four regionally persistent members: (a) the basal sandstone member, consisting of marine sandstone and shale with some conglomerate; (b) the lower shale member, consisting of nonmarine quartzite, conglomerate and shale; (c) the middle conglomerate member, consisting of nonmarine pebble and cobble conglomerate and quartzite; and (d) the Stuver Member, consisting of nonmarine sandstone and shale. The Kanayut conformably overlies the Upper Devonian marine Hunt Fork Shale and is conformably overlain by the Mississippian marine Kayak Shale. The Kanayut is wholly allochthonous and has probably been transported northward on a series of thrust plates. The basal sandstone member of the Kanayut Conglomerate, which overlies prodelta turbidites of the Hunt Fork Shale, contains marginal-marine coarsening-upward channel-mouth bar sequences. It is conformably overlain by the lower shale member. Measured sections of the nonmarine members of the Kanayut show that the lower shale member ranges in thickness from 120 m to 1115 m and consists of fining-upward cycles interpreted to have been deposited by meandering streams on a broad floodplain. These cycles contain, in ascending order, channelized basal conglomerate, trough cross-stratified sandstone, and ripple-marked siltstone. The cycles are interpreted to be channel and point-bar deposits. Individual cycles average about 10 m in thickness and are separated by intervals of black, brown or maroon floodplain shale deposits. These typically contain thin coarsening-upward units that probably represent prograding levee sequences and irregular and ungraded sandstone bodies interpreted to be crevasse-splay deposits. In the Okokmilaga River area, the lower shale member contains a

  10. Metamorphosed melange in the central Piedmont of South Carolina

    SciTech Connect

    Mittwede, S.K.; Maybin, A.H. III )

    1989-09-01

    The Enoree melange is exposed in the central Piedmont of South Carolina near the boundary between the Piedmont and Carolina terranes. The melange is composed of ultramafic and mafic blocks in a highly deformed matrix of biotite-feldspar-quartz gneiss which has a composition consistent with a felsic-to-intermediate volcanic precursor. The mafic and ultramafic blocks are separated chemically and petrographically into four compositional groups: metagabbro-clinopyroxenite, websterite, orthopyroxenite, and metasomatized (steatitized) orthopyroxenite. Based on their chemistry and mineralogy, the blocks are clearly exotic relative to their metavolcaniclastic( ) matrix and likely originated as parts of a plutonic suite from the basal or forward part of the Carolina arc terrane. If the Piedmont terrane-Carolina terrane boundary is a continent-arc suture, then the Enoree melange probably formed in the accretionary prism at this convergent margin. The matrix gneisses are interpreted as reworked volcanic debris shed by the Carolina arc terrane edifice and accumulated as graywacke in the accretionary deposits. West-vergent structures in the matrix suggest that the melange was emplaced to its present tectonostratigraphic position either during docking of the Carolina terrane or during widespread Alleghenian thrusting.

  11. Late Holocene megathrust earthquakes in south central Chile

    NASA Astrophysics Data System (ADS)

    Garrett, Ed; Shennan, Ian; Gulliver, Pauline; Woodroffe, Sarah

    2013-04-01

    A lack of comprehensive understanding of the seismic hazards associated with a subduction zone can lead to inadequate anticipation of earthquake and tsunami magnitudes. Four hundred and fifty years of Chilean historical documents record the effects of numerous great earthquakes; however, with recurrence intervals between the largest megathrust earthquakes approaching 300 years, seismic hazard assessment requires longer chronologies. This research seeks to verify and extend historical records in south central Chile using a relative-sea level approach to palaeoseismology. Our quantitative, diatom-based approaches to relative sea-level reconstruction are successful in reconstructing the magnitude of coseismic deformation during recent, well documented Chilean earthquakes. The few disparities between my estimates and independent data highlight the possibility of shaking-induced sediment consolidation in tidal marshes. Following this encouraging confirmation of the approach, we quantify land-level changes in longer sedimentary records from the centre of the rupture zone of the 1960 Valdivia earthquake. Here, laterally extensive marsh soils abruptly overlain by low intertidal sediments attest to the occurrence of four megathrust earthquakes. Sites preserve evidence of the 1960 and 1575 earthquakes and we constrain the timing of two predecessors to 1270 to 1410 and 1050 to 1200. The sediments and biostratigraphy lack evidence for the historically documented 1737 and 1837 earthquakes.

  12. Water movement in till of east-central South Dakota

    SciTech Connect

    Craven, S.J.; Ruedisili, L.C.; Barari, A.

    1985-01-01

    Factors that control the flow of water through till are poorly understood. Hydrographic analyses, field hydraulic conductivity measurements, and major-ion sampling were conducted on weathered and unweathered tills at 22 sites in east-central South Dakota. Water from a buried outwash aquifer was also chemically analyzed and carbon age dated. The upper part of most till has been weathered and exhibits extensive secondary permeability. Hydraulic conductivity values range from 10/sup -7/ to 10/sup -4/ cm/sec; typically 10 to 200 times higher than the hydraulic conductivity of unweathered till. Hydraulic gradients within weathered tills average seven times lower than within unweathered till. Water infiltrating below plant roots is believed to principally recharge and discharge the weathered till. Total dissolved solids were significantly higher in the weathered till than in the unweathered till. Water extracted from unweathered till is, in turn, up to three time higher in major-ion concentrations than water from the underlying outwash aquifer. Carbon-14 age dates from outwash aquifer water exceed 9000 years before present. Results indicate that Tittle to no water passes from the weathered till through the unweathered till into the buried outwash aquifer. Discharge from the weathered till is hypothesized to be primarily local lateral flow to sloughs, streams and ponds, combined with evapotranspiration losses during periods of high water table.

  13. Brookian sequence well log correlation sections and occurrence of gas hydrates, north-central North Slope, Alaska

    USGS Publications Warehouse

    Lewis, Kristen A.; Collett, Timothy S.

    2013-01-01

    Gas hydrates are naturally occurring crystalline, ice-like substances that consist of natural gas molecules trapped in a solid-water lattice. Because of the compact nature of their structure, hydrates can effectively store large volumes of gas and, consequently, have been identified as a potential unconventional energy source. First recognized to exist geologically in the 1960s, significant accumulations of gas hydrate have been found throughout the world. Gas hydrate occurrence is limited to environments such as permafrost regions and subsea sediments because of the pressure and temperature conditions required for their formation and stability. Permafrost-associated gas hydrate accumulations have been discovered in many regions of the Arctic, including Russia, Canada, and the North Slope of Alaska. Gas hydrate research has a long history in northern Alaska. This research includes the drilling, coring, and well log evaluation of two gas hydrate stratigraphic test wells and two resource assessments of gas hydrates on the Alaska North Slope. Building upon these previous investigations, this report provides a summary of the pertinent well log, gas hydrate, and stratigraphic data for key wells related to gas hydrate occurrence in the north-central North Slope. The data are presented in nine well log correlation sections with 122 selected wells to provide a regional context for gas hydrate accumulations and the relation of the accumulations to key stratigraphic horizons and to the base of the ice-bearing permafrost. Also included is a well log database that lists the location, available well logs, depths, and other pertinent information for each of the wells on the correlation section.

  14. Quaternary tectonic setting of South-Central coastal California

    USGS Publications Warehouse

    Lettis, William R.; Hanson, Kathryn L.; Unruh, Jeffrey R.; McLaren, Marcia; Savage, William U.; Keller, Margaret A.

    2004-01-01

    Recent geodetic, geologic, and seismologic studies show that the south-central coast of California is a region of active Quaternary deformation. Northeast-directed crustal shortening is occurring in a triangular-shaped region between the Hosgri-San Simeon fault system on the west, the Southern Coast Ranges on the northeast, and the western Transverse Ranges on the south. We informally call this region the Los Osos domain. In this study, we conducted detailed geological, seismological, and geophysical investigations to characterize the nature and rates of deformation in the domain. Locations of active and potentially active faults and folds are compiled at a scale of 1:250,000 for the entire domain based primarily on onshore geologic data and offshore geophysical data. Crustal shortening in the domain is accommodated by a series of prominent northwest-trending reverse faults and localized folding. The reverse faults separate distinct structural blocks that have little or no internal deformation. Hangingwall blocks are being uplifted at rates of up to 0.2 mm/yr. Footwall blocks are either static or slowly subsiding at rates of 0.1 mm/yr or less, except for localized areas of concentrated subsidence directly adjacent to some faults. The cumulative rate of crustal shortening is about 1 to 2 mm/yr across the northern part of the domain based on observed geologic deformation. Cumulative shortening across the central and southern parts of the domain is poorly constrained by geologic data and may approach 2 to 3 mm/yr. Historical and instrumental seismicity generally are spatially associated with the uplifted blocks and bordering reverse faults to depths of about 10 km. Together with near-surface geological data and deeper crustal geophysical imaging that show high-angle faulting, the seismicity data indicate that the reverse faults probably extend to the base of the seismogenic crust. The base of the seismogenic crust may correspond with a mid-crustal detachment or

  15. Shallow-water habitat use by Bering Sea flatfishes along the central Alaska Peninsula

    NASA Astrophysics Data System (ADS)

    Hurst, Thomas P.

    2016-05-01

    Flatfishes support a number of important fisheries in Alaskan waters and represent major pathways of energy flow through the ecosystem. Despite their economic and ecological importance, little is known about the use of habitat by juvenile flatfishes in the eastern Bering Sea. This study describes the habitat characteristics of juvenile flatfishes in coastal waters along the Alaska Peninsula and within the Port Moller-Herendeen Bay system, the largest marine embayment in the southern Bering Sea. The two most abundant species, northern rock sole and yellowfin sole, differed slightly in habitat use with the latter occupying slightly muddier substrates. Both were more common along the open coastline than they were within the bay, whereas juvenile Alaska plaice were more abundant within the bay than along the coast and used shallow waters with muddy, high organic content sediments. Juvenile Pacific halibut showed the greatest shift in distribution between age classes: age-0 fish were found in deeper waters (~ 30 m) along the coast, whereas older juveniles were found in the warmer, shallow waters within the bay, possibly due to increased thermal opportunities for growth in this temperature-sensitive species. Three other species, starry flounder, flathead sole, and arrowtooth flounder, were also present, but at much lower densities. In addition, the habitat use patterns of spring-spawning flatfishes (northern rock sole, Pacific halibut, and Alaska plaice) in this region appear to be strongly influenced by oceanographic processes that influence delivery of larvae to coastal habitats. Overall, use of the coastal embayment habitats appears to be less important to juvenile flatfishes in the Bering Sea than in the Gulf of Alaska.

  16. Paleoclimatic significance of chemical weathering in loess-derived paleosols of subarctic central Alaska

    USGS Publications Warehouse

    Muhs, D.R.; Ager, T.A.; Skipp, G.; Beann, J.; Budahn, J.; McGeehin, J.P.

    2008-01-01

    Chemical weathering in soils has not been studied extensively in high-latitude regions. Loess sequences with modern soils and paleosols are present in much of subarctic Alaska, and allow an assessment of present and past chemical weathering. Five sections were studied in detail in the Fairbanks, Alaska, area. Paleosols likely date to mid-Pleistocene interglacials, the last interglacial, and early-to-mid-Wisconsin interstadiale. Ratios of mobile (Na, Ca, Mg, Si) to immobile (Ti or Zr) elements indicate that modern soils and most interstadial and interglacial paleosols are characterized by significant chemical weathering. Na2O/TiO2 is lower in modern soils and most paleosols compared to parent loess, indicating depletion of plagioclase. In the clay fraction, smectite is present in Tanana and Yukon River source sediments, but is absent or poorly expressed in modern soils and paleosols, indicating depletion of this mineral also. Loss of both plagioclase and smectite is well expressed in soils and paleosols as lower SiO 2/TiO2. Carbonates are present in the river source sediments, but based on CaO/TiO2, they are depleted in soils and most paleosols (with one exception in the early-to-mid-Wisconsin period). Thus, most soil-forming intervals during past interglacial and interstadial periods in Alaska had climatic regimes that were at least as favorable to mineral weathering as today, and suggest boreal forest or acidic tundra vegetation. ?? 2008 Regents of the University of Colorado.

  17. Index to limnological data for southcentral Alaska Lakes

    USGS Publications Warehouse

    Maurer, M.A.; Woods, P.F.

    1987-01-01

    South-central Alaska lakes are a valuable natural resource and provide a variety of recreational opportunities to the public. Lakeside development has increased significantly in the past 10 years and several south-central Alaskan lakes have documented pollution problems. Cultural eutrophication, the process by which man-induced nutrient loading to a lake results in large increases in biological productivity, can also produce noxious algae blooms, dissolved oxygen depletion at depth, reduced water transparency, and fish kills. The potential for cultural eutrophication of south-central Alaska lakes prompted the U.S. Geological Survey (USGS) Water Resources Division and the Alaska Department of Natural Resources-Division of Geological and Geophysical Surveys (ADGGS) to provide lake researchers, managers, and the public with this index of published historical and current limnological references. The purpose of the index is to provide reference to the data which can be used to identify and monitor cultural eutrophication of south-central Alaska lakes. (Lantz-PTT)

  18. Control of Orange Hawkweed (Hieracium aurantiacum) in Southern Alaska

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Orange hawkweed is a perennial European plant and an escaped ornamental that has colonized roadsides and grasslands in south central and southeast Alaska. This plant is forming near monotypic stands, reducing plant diversity and decreasing pasture productivity. A replicated greenhouse study was cond...

  19. Stratigraphy and palaeoclimatic significance of Late Quaternary loess-palaeosol sequences of the Last Interglacial-Glacial cycle in central Alaska

    USGS Publications Warehouse

    Muhs, D.R.; Ager, T.A.; Bettis, E. Arthur; McGeehin, J.; Been, J.M.; Beget, J.E.; Pavich, M.J.; Stafford, Thomas W.; Stevens, D.A.S.P.

    2003-01-01

    Loess is one of the most widespread subaerial deposits in Alaska and adjacent Yukon Territory and may have a history that goes back 3 Ma. Based on mineralogy and major and trace element chemistry, central Alaskan loess has a composition that is distinctive from other loess bodies of the world, although it is quartz-dominated. Central Alaskan loess was probably derived from a variety of rock types, including granites, metabasalts and schists. Detailed stratigraphic data and pedologic criteria indicate that, contrary to early studies, many palaeosols are present in central Alaskan loess sections. The buried soils indicate that loess sedimentation was episodic, or at least rates of deposition decreased to the point where pedogenesis could keep ahead of aeolian input. As in China, loess deposition and pedogenesis are likely competing processes and neither stops completely during either phase of the loess/soil formation cycle. Loess deposition in central Alaska took place before, and probably during the last interglacial period, during stadials of the mid-Wisconsin period, during the last glacial period and during the Holocene. An unexpected result of our geochronological studies is that only moderate loess deposition took place during the last glacial period. Our studies lead us to conclude that vegetation plays a key role in loess accumulation in Alaska. Factors favouring loess production are enhanced during glacial periods but factors that favour loess accumulation are diminished during glacial periods. The most important of these is vegetation; boreal forest serves as an effective loess trap, but sparsely distributed herb tundra does not. Thus, thick accumulations of loess should not be expected where tundra vegetation was dominant and this is borne out by modern studies near the treeline in central Alaska. Much of the stratigraphic diversity of North American loess, including that found in the Central Lowlands, the Great Plains, and Alaska is explained by a new

  20. Unraveling tectonics and climate forcing in the late-Neogene exhumation history of South Alaska

    NASA Astrophysics Data System (ADS)

    Valla, Pierre; Champagnac, Jean-Daniel; Shuster, David; Herman, Frédéric; Giuditta Fellin, Maria

    2015-04-01

    The southern Alaska range presents an ideal setting to study the complex interactions between tectonics, climate and surface processes in landscape evolution. It exhibits active tectonics with the ongoing subduction/collision between Pacific and North America, and major active seismogenic reverse and strike-slip faults. The alpine landscape, rugged topography and the important ice-coverage at present reveal a strong glacial imprint associated with high erosion and sediment transport rates. Therefore, the relative importance of climatically-driven glacial erosion and tectonics for the observed late-exhumation history appears to be quite complex to decipher. Here, we first perform a formal inversion of an extensive bedrock thermochronological dataset from the literature to quantify the large-scale 20-Myr exhumation history over the entire southern Alaska. We show that almost half of the variability within the thermochronological record can be explained by modern annual precipitations spatial distribution, the residuals clearly evidencing localized exhumation along major tectonic structures of the frontal fold and thrust belt. Our results confirm high exhumation rates in the St Elias "syntaxis" and frontal zones for the last 0-2 Myr, where major ice fields and high precipitation rates likely sustained high exhumation rates; however the impact of late Cenozoic glaciations is difficult to constrain because of the low resolution on the exhumation history older than ~2 Myr. On the contrary, our inversion outcomes highlight that north of the Bagley Icefield the long-term exhumation has remained quite slow and continuous over the last ~20 Myr, with no late-stage signal of exhumation change since the onset of glaciations despite a clear glacial imprint on the landscape. We thus focus on the Granite Range (Wrangell-St Elias National Park, Alaska), an area presenting a strong glacial imprint but minor tectonic activity with only localized brittle deformation. We sampled four

  1. Characterization of the mississippian chat in South-central Kansas

    USGS Publications Warehouse

    Watney, W.L.; Guy, W.J.; Byrnes, A.P.

    2001-01-01

    To understand production from low resistivity-high porosity Mississippian chat reservoirs in south-central Kansas it is necessary to understand the nature of deposition and diagenesis, how tectonics is a factor, the lithofacies controls on petrophysical properties, and log response to these properties. The initial mudstones to sponge-spicule wacke-packstones were deposited in transgressive-regressive (T-R) cycles on a shelf to shelf margin setting, resulting in a series of shallowing-upward cycles. Sponge-spicule content appears to increase upward with increasing cycle thickness. After early silicification, inter- and post-Mississippian subaerial exposure resulted in further diagenesis, including sponge-spicule dissolution, vuggy porosity development in moldic-rich rocks, and autobrecciation. Meteoric water infiltration is limited in depth below the exposure surface and in distance downdip into unaltered, cherty Cowley Formation facies. Areas of thicker preserved chat and increased diagenesis can be correlated with structural lineaments and, in some areas, with recurrent basement block movement. Combination of folding or block fault movement prior to or during development of the basal Pennsylvanian unconformity, sponge-spicule concentration, and possibly thickness of overlying bioclastic wacke-grainstones resulted in variable reservoir properties and the creation of pods of production separated by nonproductive cherty dolomite mudstones. These events also resulted in alteration of the depositional cycles to produce a series of lithofacies that exhibit unique petrophysical properties. From bottom to top in a complete cycle seven lithofacies are present: (1) argillaceous dolomite mudstone, (2) argillaceous dolomite mudstone that has chert nodules, (3) clean dolomite mudstone that has nodular chert, (4) nodular to bedded chert, (5) autoclastic chert, (6) autoclastic chert that has clay infill, and (7) bioclastic wacke-grainstone. The uppermost cycle was terminated by

  2. Movement patterns of coyotes in south central Washington

    SciTech Connect

    Springer, J.T.

    1982-01-01

    Ten coyotes (Canis latrans) fitted with radio transmitters on the U.S. Department of Energy Hanford Reservation in south central Washington were located daily over periods of 1-15 months. Because 82.9 of all locations were concentrated in only 6.9% of the total home range area, each home range was subdivided into an ''impact area'' and 1 or more ''core areas.'' An ''impact area'' was defined as an area through which a coyote traveled and within which it might have interacted with other animals. ''Core areas'' were relatively small regions of concentrated use. No relationships were found between daily movements and relative and absolute changes in mean daily temperature and mean daily barometric pressure, or moon phases. The measured movement parameters of daily movement, core area size, and home range size, respectively, changed by seasons: fall, 3.1 km, 5.3 km/sup 2/, 98.6 km/sup 2/; winter, 4.7 km, 13.2 km/sup 2/, 143 km/sup 2/; spring, 2.6 km, 8.3 km/sup 2/, 58.2 km/sup 2/; summer, 3.3 km/sup 2/, 54.5 km/sup 2/; overall, 3.4 km, 7.9 km/sup 2/, 92.4 km/sup 2/. Home ranges measured were larger than averages reported in the literature. The coyotes studied were subject to levels of disturbance lower than those reported for other populations.

  3. Hydrology of the Oakley Fan Area, south-central Idaho

    USGS Publications Warehouse

    Young, H.W.; Newton, G.D.

    1989-01-01

    The Oakley Fan area is a broad, crescent-shaped lowland along the southern margin of the Snake River Plain in south-central Idaho. Intensive groundwater development for irrigation has resulted in rapid water-level declines and, as a consequence, designation by the State of four Critical Groundwater Areas. Principal aquifers are in limestone, rhyolite, basalt, and alluvium. Annual water-level declines range from 3 ft to about 5 ft. Recharge to the groundwater system is from infiltration of surface water used for irrigation, precipitation on the surrounding mountains, infiltration of localized runoff, and upward movement of thermal water. Groundwater pumpage during the period 1979-84 averaged 173,000 acre-ft/yr. Surface and groundwater is predominantly a calcium bicarbonate type with variable concentrations of dissolved solids. Comparisons of silica and chloride concentrations and isotopic composition of groundwater were useful in determining areal extent of aquifers and movement of groundwater. A three-dimensional mathematical model of the Oakley Fan area was developed. The aquifer system was simulated in three phases: (1) Average 1979-84 hydrologic conditions, (2) 1910 hydrologic conditions, and (3) 1910-84 hydrologic conditions. Model simulation indicated that, for the period 1945-79, subsurface outflow declined from 327,000 acre-ft/yr to 215,000 acre-ft/yr. Simulated groundwater pumpage during the period 1945-79 was 3,000,000 acre-ft; simulated change in storage was 250,000 acre-ft. Simulations with the model approximate natural conditions and probably can be used to evaluate future changes in the hydrologic system.

  4. Diabetes in South and Central America: an update.

    PubMed

    Aschner, Pablo; Aguilar-Salinas, Carlos; Aguirre, Loreto; Franco, Laercio; Gagliardino, Juan Jose; de Lapertosa, Sylvia Gorban; Seclen, Segundo; Vinocour, Mary

    2014-02-01

    The estimated population of the South and Central America (SACA) Region is 467.6 million and 64% is in the age range of 20-79 years but the population pyramid and age distribution are changing. The average prevalence of diabetes in the Region is 8.0% and is expected to reach 9.8% by the year 2035. Prevalence is much lower in rural settings than in urban and the differences attributed to lifestyle changes may be a target for intervention. The indigenous population is a particularly vulnerable group needing special attention. On average, 24% of the adult cases with diabetes are undiagnosed but in some countries this is still as high as 50%. Health expenditure due to diabetes in the Region is around 9% of the global total. Inadequate glycemic control, defined as HbA1c >7%, is a strong predictor of chronic complications which increase resource use in the Region and less than half of the patients enrolled in diabetes care programmes are at target. Fifty percent or more of the adult population is overweight/obese and around one third of the adult population has metabolic syndrome using regional cutoffs for waist circumference. The number of people with IGT is almost equal to those with diabetes presenting an additional challenge for prevention. Children with type 1 diabetes represent only 0.2% of the total population with diabetes but the incidence may be increasing. In many places they have limited access to insulin, and even when available, it is not used appropriately. The available epidemiological data provide the background to act in developing national diabetes programmes which integrate diabetes care with cardiovascular prevention and promote diabetes prevention as well.

  5. Coordination and establishment of centralized facilities and services of the University of Alaska ERTS survey of the Alaskan environment

    NASA Technical Reports Server (NTRS)

    Belon, A. E. (Principal Investigator); Miller, J. M.

    1973-01-01

    The author has identified the following significant results. The objective of this project is to provide a focus for the entire University of Alaska ERTS-1 effort (12 projects covering 10 disciplines and involving 8 research institutes and science departments). Activities have been concentrated on the implementation of the project's three primary functions: (1) coordination and management of the U of A ERTS-1 program, including management of the flow of data and data products; (2) acquisition, installation, test, operation, and maintanence of centralized facilities for processing ERTS-1, aircraft, and ground truth data; and (3) development of photographic and digital techniques for processing and interpreting ERTS-1 and aircraft data. With minor exceptions these three functions are now well-established and working smoothly.

  6. High-pressure amphibolite facies dynamic metamorphism and the Mesozoic tectonic evolution of an ancient continental margin, east- central Alaska

    USGS Publications Warehouse

    Dusel-Bacon, C.; Hansen, V.L.; Scala, J.A.

    1995-01-01

    Ductilely deformed amphibolite facies tectonites comprise two adjacent terranes in east-central Alaska: the northern, structurally higher Taylor Mountain terrane and the southern, structurally lower Lake George subterrane of the Yukon-Tanana terrane. The pressure, temperature, kinematic and age data are interpreted to indicate that the metamorphism of the Taylor Mountain terrane and Lake George subterrane took place during different phases of a latest Palaeozoic through early Mesozoic shortening episode resulting from closure of an ocean basin now represented by klippen of the Seventymile-Slide Mountain terrane. High- to intermediate-pressure metamorphism of the Taylor Mountain terrane took place within a SW-dipping (present-day coordinates) subduction system. High- to intermediate-pressure metamorphism of the Lake George subterrane and the structural contact zone occurred during NW-directed overthrusting of the Taylor Mountain, Seventymile-Slide Mountain and Nisutlin terranes, and imbrication of the continental margin in Jurassic time. -from Authors

  7. Along-Strike Geochemical Variations in the Late Triassic Nikolai Magmatic System, Wrangellia, Central Alaska

    NASA Astrophysics Data System (ADS)

    Wypych, A.; Twelker, E.; Lande, L. L.; Newberry, R.

    2015-12-01

    The Nikolai Basalt and related mafic to ultramafic intrusions are one of the world's most complete and best exposed sections of a large igneous province (Amphitheater Mountains, Alaska), and have been explored for magmatic Ni-Cu-Co-PGE mineralization (Wellgreen deposit in the Kluane Ranges, Yukon Territory, and Eureka zone in the Eastern Alaska Range). The full extent of the basalts and the intrusions, as well as along-strike variations in the geochemical and petrological composition and the causes for those variations has yet to be fully established. To better understand the extent and magmatic architecture of this system, the Alaska Division of Geological & Geophysical Surveys conducted mapping and geochemical investigations of the province from 2013 through 2015 field seasons. We present major and trace element data from whole rock, olivine, and chromite from samples of Triassic basalts and intrusives collected over a 250 km along-strike transect. This data is used to answer questions about variations in magma generation, temperature of crystallization, and degree of fractional crystallization required to produce the Nikolai Basalts. Using chalcophile elements, we examine the history of sulfide solubility, further adding to our understanding of the processes of magma evolution and its influence on the formation of economic mineral deposits. Our initial findings corroborate the presence of two phases of magma generation and eruption, as well as along-strike variation in composition of these phases. We propose that the major along-strike variations are due to differences in amount of cumulate olivine and other late-stage processes. This magmatic architecture has important implications for exploration for magmatic sulfide deposits of nickel-copper and strategic and critical platinum group elements (PGEs) as it can help to better understand the occurrences and point to future possible deposits within the system.

  8. A 2000 year varve-based climate record from the central Brooks Range, Alaska

    SciTech Connect

    Bird, B.W.; Abbott, M.B.; Finney, B.P.; Kutchko, Barbara

    2009-01-01

    Varved minerogenic sediments from glacial-fed Blue Lake, northern Alaska, are used to investigate late Holocene climate variability. Varve thickness measurements track summer temperature recorded at Atigun Pass, located 41 km east at a similar elevation (r2 = 0.31, P = 0.08). Results indicate that climate in the Brooks Range from 10 to 730 AD (varve year) was warm with precipitation inferred to be higher than during the twentieth century. The varve-temperature relationship for this period was likely compromised and not used in our temperature reconstruction because the glacier was greatly reduced, or absent, exposing sub-glacial sediments to erosion from enhanced precipitation.

  9. A geochemical sampling technique for use in areas of active alpine glaciation: an application from the central Alaska Range

    USGS Publications Warehouse

    Stephens, G.C.; Evenson, E.B.; Detra, D.E.

    1990-01-01

    In mountainous regions containing extensive glacier systems there is a lack of suitable material for conventional geochemical sampling. As a result, in most geochemical sampling programs a few stream-sediment samples collected at, or near, the terminus of valley glaciers are used to evaluate the mineral potential of the glaciated area. We have developed and tested a technique which utilizes the medial moraines of valley glaciers for systematic geochemical exploration of the glacial catchment area. Moraine sampling provides geochemical information that is site-specific in that geochemical anomalies can be traced directly up-ice to bedrock sources. Traverses were made across the Trident and Susitna glaciers in the central Alaska Range where fine-grained (clay to sand size) samples were collected from each medial moraine. These samples were prepared and chemically analyzed to determine the concentration of specific elements. Fifty pebbles were collected at each moraine for archival purposes and for subsequent lithologic identification. Additionally, fifty cobbles and fifty boulders were examined and described at each sample site to determine the nature and abundance of lithologies present in the catchment area, the extent and nature of visible mineralization, the presence and intensity of hydrothermal alteration and the existence of veins, dikes and other minor structural features. Results from the central Alaska Range have delineated four distinct multi-element anomalies which are a response to potential mineralization up-ice from the medial moraine traverse. By integrating the lithologic, mineralogical and geochemical data the probable geological setting of the geochemical anomalies is determined. ?? 1990.

  10. Sedimentology and sequence stratigraphy of the Cretaceous Nanushuk, Seabee, and Tuluvak formations exposed on Umiat Mountain, north-central Alaska

    USGS Publications Warehouse

    Houseknecht, David W.; Schenk, Christopher J.

    2005-01-01

    Upper Cretaceous strata of the upper part of the Nanushuk Formation, the Seabee Formation, and the lower part of the Tuluvak Formation are exposed along the Colville River on the east flank of Umiat Mountain in north-central Alaska. The Ninuluk sandstone, which is the uppermost unit of the Nanushuk Formation, displays a vertical succession of facies indicative of deposition in an upward-deepening estuarine through shoreface setting. A marine-flooding surface lies between the Ninuluk sandstone and organic-rich shale of the basal part of the Seabee Formation. The Ninuluk sandstone and the lower part of the Seabee Formation are interpreted as components of a transgressive-systems tract. The lowest, well-exposed strata in the Seabee Formation are a succession of shoreface sandstone beds in the middle of the formation. Integration of outcrop information and the Umiat No. 11 well log suggests that this sandstone succession rests on a sequence boundary and is capped by a marine-flooding surface. The sandstone succession is interpreted as a lowstand-systems tract. The upper part of the Seabee Formation includes a thick interval of organic-rich shale deposited in a dysaerobic offshore environment, and the gradational Seabee-Tuluvak contact is a coarsening-upward shale-to-sandstone succession deposited in a prodelta/delta-front environment. The observation that the upper part of the Seabee Formation correlates with seismic clinoforms suggests that dysaerobic conditions extended well up onto the prodelta slope during intervals of transgression and highstand. Correlation of the Umiat Mountain outcrop section with well logs and seismic data suggests that sequence boundaries and lowstand shoreface deposits may be common in the Seabee Formation and that wave action may have been important in transporting sand to the paleoshelf margin. These conclusions may contribute to an enhanced understanding of sand distribution in prospective lowstand turbidite deposits in the subsurface of

  11. Assessment of coalbed gas resources of the Central and South Sumatra Basin Provinces, Indonesia, 2016

    USGS Publications Warehouse

    Schenk, Christopher J.; Klett, Timothy R.; Tennyson, Marilyn E.; Mercier, Tracey J.; Brownfield, Michael E.; Pitman, Janet K.; Gaswirth, Stephanie B.; Finn, Thomas M.

    2016-12-09

    Using a geology-based assessment methodology, the U.S. Geological Survey estimated a mean of 20 trillion cubic feet of undiscovered, technically recoverable coalbed gas resource in the Central and South Sumatra Basin Provinces of Indonesia.

  12. Particulate Matter Concentration Levels in South Central Richmond, California (Invited)

    NASA Astrophysics Data System (ADS)

    Bonner, B.; Byias, C.; Cuff, K. E.; Diaz, J.; Love, K.; Marks-Block, T.; McLane, F.; Mollique, Z.; Montes, E.; Ross, R.; Washington, B.

    2009-12-01

    South Central Richmond, California is the home of one of the nation’s most innovative green workforce training centers, Richmond BUILD - Green Jobs Training facility. A near constant stream of young people engaged in training activities, instructors, invited guests, and journalists of various ages can be seen moving in and out of the facility nearly every day of the week throughout a given year. Additionally, the comings and goings of young children and adults associated with a mid-sized elementary school just north of the facility contributes to the general area’s substantial human traffic. Unfortunately, however, a major highway, Interstate 580, a major thoroughfare, 23rd Street and a railway line operated by Burlington Northern Santa Fe, Union Pacific, and the Richmond Pacific Railroad frame the triangular area within which these two sites are situated. In addition, a major petrochemical complex and several shipping facilities are located less than three kilometers away north and west of this area. As part of a general assessment of air quality in this heavily human traveled area, we conducted a study of particulate matter (PM) concentrations over a five-month period beginning in August of 2009. Measurements were made at a variety of locations, and results were used to map the spatial distribution of PM of various sizes. Regions of high concentration levels were identified, and these particular areas then were monitored over time. Preliminary results of our study indicate that regions with high concentrations are consistent across the range of particle sizes measured, which suggests a common source for PM found in the study area. As these regions are located close to a major thoroughfare and railway line, we believe that diesel-burning vehicles are major contributors to the PM levels found in the study area. Time series results suggest a fairly strong correlation between higher than average PM concentrations and abnormally high wind gusts. On days when wind

  13. 78 FR 16028 - Waiver of Restriction on Assistance to the Central Government of South Sudan

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-13

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF STATE Waiver of Restriction on Assistance to the Central Government of South Sudan Pursuant to Section 7031(b)(3... Section 7031(b)(1) of the Act with respect to South Sudan, and I hereby waive this restriction....

  14. Agrolandscape Research of Geosystems in the South of Central Siberia

    NASA Astrophysics Data System (ADS)

    Lysanova, G.; Soja, A. J.

    2012-12-01

    Minusinskaya basin, the area under research, is situated in the south of Central Siberia and is an agrarian region, which differs from another territories of Siberia. The territory provides for foodstuff not only its population but another regions as well. Nature-climate conditions favour the development of agriculture and cattle-breeding. Complex geographical study of rural lands, which is implemented by two approaches: a natural and industrial system block is necessary for rational use of agrolandscapes. Agrolandscapes are objects for rationalization of land management in agricultural regions. From our point of view application of a landscape map as a base for working out of agrolandscape map (Fig. 1a) and a map of agronatural potential of geosystems (Fig. 2), gives an opportunity to take stock of reserves of agricultural lands not only in quantitative but qualitative respects and also to determine the ways of optimal transformation of arable lands depending on nature conditions of regions and their development. Landscape maps that reflect differentiation of not only natural formations, changed by anthropogenious influence and also natural analogues, concern to a number of important tools of planning for optimal land use. The main principles of working out of typological landscape map of a medium scale aroused from targets and tasks of agrolandscape estimation of the territory [1]. The landscape map was worked out according to V.A. Nikolaev's methodology [2]: types of landscapes correlated with types of lands use, composition of cereals in rotation of crops, agro-techniques, crop capacity, climate indices, etc. Existing natural-agricultural systems are shown in the map. Their characteristics includes information about natural and agricultural blocks. Agronatural potential had been calculated by summarize estimations of its component parts. As a result of these calculations 30 arable agrolandscapes, marked out into the landscape map, were joined according to summ

  15. Variation in responses to spawning Pacific salmon among three south-eastern Alaska streams

    USGS Publications Warehouse

    Chaloner, D.T.; Lamberti, G.A.; Merritt, R.W.; Mitchell, N.L.; Ostrom, P.H.; Wipfli, M.S.

    2004-01-01

    1. Pacific salmon are thought to stimulate the productivity of the fresh waters in which they spawn by fertilising them with marine-derived nutrients (MDN). We compared the influence of salmon spawners on surface streamwater chemistry and benthic biota among three southeastern Alaska streams. Within each stream, reaches up- and downstream of barriers to salmon migration were sampled during or soon after spawners entered the streams. 2. Within streams, concentrations of dissolved ammonium and soluble reactive phosphorus (SRP), abundance of epilithon (chlorophyll a and ash-free dry mass) and biomass of chironomids were significantly higher in reaches with salmon spawners. In contrast, biomass of the mayflies Epeorus spp. and Rhithrogena spp. was significantly higher in reaches lacking spawners. 3. Among streams, significant differences were found in concentrations of dissolved ammonium, dissolved organic carbon, nitrate and SRP, abundance of epilithon, and the biomass of chironomids and Rhithrogena. These differences did not appear to reflect differences among streams in spawner density, nor the changes in water chemistry resulting from salmon spawners. 4. Our results suggest that the 'enrichment' effect of salmon spawners (e.g. increased streamwater nutrient concentrations) was balanced by other concurrent effects of spawners on streams (e.g. sediment disturbance). Furthermore, the collective effect of spawners on lotic ecosystems is likely to be constrained by conditions unique to individual streams, such as temperature, background water chemistry and light attenuation.

  16. Glacimarine sedimentary processes, facies and morphology of the south-southeast Alaska shelf and fjords

    USGS Publications Warehouse

    Powell, R.D.; Molnia, B.F.

    1989-01-01

    High precipitation from Gulf of Alaska air masses can locally reach up to 800 cm a-1. This precipitation on tectonically active mountains creates cool-temperate glaciation with extremely active erosion and continuously renewed resources. High basal debris loads up to 1.5 m thick of pure debris and rapid glacial flow, which can be more than 3000 m a-1, combine to produce large volumes of siliciclastic glacimarine sediment at some of the highest sediment accumulation rates on record. At tidewater fronts of valley glaciers, sediment accumulation rates can be over 13 m a-1 and deltas commonly grow at about 106 m3 a-1. Major processes influencing glacimarine sedimentation are glacial transport and glacier-contact deposition, meltwater (subaerial and submarine) and runoff transport and deposition, iceberg rafting and gouging, sea-ice transport, wave action and storm reworking, tidal transport and deposition, alongshelf transport, sliding and slumping and gravity flows, eolian transport, and biogenic production and reworking. Processes are similar in both shelf and fjord settings; however, different intensities of some processes create different facies associations and geometries. The tectonoclimatic regime also controls morphology because bedrock structure is modified by glacial action. Major glacimarine depositional systems are all siliciclastic. They are subglacial, marginal-morainal bank and submarine outwash, and proglacial/paraglacial-fluvial/deltaic, beach, tidal flat/estuary, glacial fjord, marine outwash fjord and continental shelf. Future research should include study of long cores with extensive dating and more seismic surveys to evaluate areal and temporal extent of glacial facies and glaciation; time-series oceanographic data, sidescan sonar surveys and submersible dives to evaluate modern processes; biogenic diversity and production to evaluate paleoecological, paleobiogeographic and biofacies analysis; and detailed comparisons of exposed older rock of the

  17. The Yukon Flats Cretaceous(?)-Tertiary Extensional Basin, East-Central Alaska: Burial and Thermal History Modeling

    USGS Publications Warehouse

    Rowan, Elisabeth L.; Stanley, Richard G.

    2008-01-01

    One-dimensional burial and thermal history modeling of the Yukon Flats basin, east-central Alaska, was conducted as part of an assessment of the region's undiscovered oil and gas resources. No deep exploratory wells have been drilled in the Yukon Flats region, and the subsurface geology of the basin is inferred from seismic reflection, gravity and magnetic surveys, and studies of shallow core holes in the basin and outcrops in the surrounding region. A thick sequence of Upper Cretaceous(?) and Cenozoic nonmarine sedimentary rocks is believed to fill the basin; coal and organic-rich mudstone and shale within this sequence represent potential hydrocarbon source rocks. The burial and thermal history models presented here represent the sole source of information on the thermal maturity of these potential source rocks at depth. We present four alternative burial history scenarios for a hypothetical well through the deepest portion of Yukon Flats basin. They differ from each other in the thicknesses of Upper Cretaceous and Cenozoic strata, the timing of initial basin subsidence, and the timing of inferred unconformities. The burial modeling results suggest a present-day depth to the oil window of approximately 6,000 feet.

  18. Geologic Model for Oil and Gas Assessment of the Kemik-Thomson Play, Central North Slope, Alaska

    USGS Publications Warehouse

    Schenk, Christopher J.; Houseknecht, David W.

    2008-01-01

    A geologic model was developed to assess undiscovered oil and gas resources in the Kemik-Thomson Play of the Central North Slope, Alaska. In this model, regional erosion during the Early Cretaceous produced an incised valley system on the flanks and crest of the Mikkelsen High and formed the Lower Cretaceous unconformity. Locally derived, coarse-grained siliciclastic and carbonate detritus from eroded Franklinian-age basement rocks, Carboniferous Kekiktuk Conglomerate (of the Endicott Group), Lisburne Group, and Permian-Triassic Sadlerochit Group may have accumulated in the incised valleys during lowstand and transgression, forming potential reservoirs in the Lower Cretaceous Kemik Sandstone and Thomson sandstone (informal term). Continued transgression resulted in the deposition of the mudstones of the over-lying Cretaceous pebble shale unit and Hue Shale, which form top seals to the potential reservoirs. Petroleum from thermally mature facies of the Triassic Shublik Formation, Jurassic Kingak Shale, Hue Shale (and pebble shale unit), and the Cretaceous-Tertiary Canning Formation might have charged Thomson and Kemik sandstone reservoirs in this play during the Tertiary. The success of this play depends largely upon the presence of reservoir-quality units in the Kemik Sandstone and Thomson sandstone.

  19. Milankovitch insulation forcing and cyclic formation of large-scale glacial, fluvial, and eolian landforms in central Alaska

    NASA Technical Reports Server (NTRS)

    Beget, J. E.

    1993-01-01

    Continuous marine and ice-core proxy climate records indicate that the Earth's orbital geometry modulates long-term changes. Until recently, little direct evidence has been available to demonstrate correlations between Milankovitch cycles and large-scale terrestrial landforms produced during worldwide glaciations. In central Alaska large areas of loess and sand fill valleys and basins near major outwash streams. The streams themselves are bordered by sets of outwash terraces, and the terraces grade up valley into sets of moraines. The discovery of the Stampede tephra (approximately 175,000 yr ago) reworked within push moraines of the Lignite Creek glaciation suggests that this event correlates with the glaciation of marine isotope stage 6. A new occurrence of the Old Crow tephra (approximately 140,000 yr ago) on the surface of the oldest outwash terrace of the Tanana River, correlated with Delta glaciation, suggests this event also occurred at this time. The penultimate Healy glaciation apparently correlates with marine isotope stage 4, while radiocarbon dates indicate the latest Pleistocene moraines correlate with marine isotope stage 2. Recognition of the importance of orbital forcing to the cyclical formation of glacial landforms and landscapes can help in interpretations of remotely sensed glacial and proglacial land forms.

  20. Increased wetness confounds Landsat-derived NDVI trends in the central Alaska North Slope region, 1985-2011

    NASA Astrophysics Data System (ADS)

    Raynolds, Martha K.; Walker, Donald A.

    2016-08-01

    Satellite data from the circumpolar Arctic have shown increases in vegetation indices correlated to warming air temperatures (e.g. Bhatt et al 2013 Remote Sensing 5 4229-54). However, more information is needed at finer scales to relate the satellite trends to vegetation changes on the ground. We examined changes using Landsat TM and ETM+ data between 1985 and 2011 in the central Alaska North Slope region, where the vegetation and landscapes are relatively well-known and mapped. We calculated trends in the normalized difference vegetation index (NDVI) and tasseled-cap transformation indices, and related them to high-resolution aerial photographs, ground studies, and vegetation maps. Significant, mostly negative, changes in NDVI occurred in 7.3% of the area, with greater change in aquatic and barren types. Large reflectance changes due to erosion, deposition and lake drainage were evident. Oil industry-related changes such as construction of artificial islands, roads, and gravel pads were also easily identified. Regional trends showed decreases in NDVI for most vegetation types, but increases in tasseled-cap greenness (56% of study area, greatest for vegetation types with high shrub cover) and tasseled-cap wetness (11% of area), consistent with documented degradation of polygon ice wedges, indicating that increasing cover of water may be masking increases in vegetation when summarized using the water-sensitive NDVI.

  1. 48 CFR 225.7704 - Acquisitions of products and services from South Caucasus/Central and South Asian (SC/CASA) state...

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 48 Federal Acquisition Regulations System 3 2011-10-01 2011-10-01 false Acquisitions of products and services from South Caucasus/Central and South Asian (SC/CASA) state in support of operations in... and South Asian (SC/CASA) state in support of operations in Afghanistan....

  2. Late Mesozoic and Cenozoic thermotectonic evolution of the central Brooks Range and adjacent North Slope foreland basin, Alaska: Including fission track results from the Trans-Alaska Crustal Transect (TACT)

    USGS Publications Warehouse

    O'Sullivan, P. B.; Murphy, J.M.; Blythe, A.E.

    1997-01-01

    Apatite fission track data are used to evaluate the thermal and tectonic history of the central Brooks Range and the North Slope foreland basin in northern Alaska along the northern leg of the Trans-Alaska Crustal Transect (TACT). Fission track analyses of the detrital apatite grains in most sedimentary units resolve the timing of structures and denudation within the Brooks Range, ranging in scale from the entire mountain range to relatively small-scale folds and faults. Interpretation of the results indicates that rocks exposed within the central Brooks Range cooled rapidly from paleotemperatures 110?? to 50??C during discrete episodes at ???100??5 Ma, ???60??4 Ma, and ???24??3 Ma, probably in response to kilometer-scale denudation. North of the mountain front, rocks in the southern half of the foreland basin were exposed to maximum paleotemperatures 110??C in the Late Cretaceous to early Paleocene as a result of burial by Upper Jurassic and Cretaceous sedimentary rocks. Rapid cooling from these elevated paleotemperatures also occurred due to distinct episodes of kilometer-scale denudation at ???60??4 Ma, 46??3 Ma, 35??2 Ma, and ???24??3 Ma. Combined, the apatite analyses indicate that rocks exposed along the TACT line through the central Brooks Range and foreland basin experienced episodic rapid cooling throughout the Late Cretaceous and Cenozoic in response to at least three distinct kilometer-scale denudation events. Future models explaining orogenic events in northern Alaska must consider these new constraints from fission track thermochronology. Copyright 1997 by the American Geophysical Union.

  3. Microbial enzyme activities of peatland soils in south central Alaska lowlands

    EPA Science Inventory

    Microbial enzyme activities related to carbon and nutrient acquisition were measured on Alaskan peatland soils as indicators of nutrient limitation and biochemical sustainability. Peat decomposition is mediated by microorganisms and enzymes that in turn are limited by various ph...

  4. Use of Radarsat-2 Polarimetric SAR Images for Fuel Moisture Mapping in Alaska Boreal Forests and South Africa Savannahs

    NASA Astrophysics Data System (ADS)

    Leblon, B.; Bourgeau-Chavez, L. L.; Kong, M.; Buckley, J. R.; Mathieu, R. M.; Charbonneau, F.; Gross, C. P.; Naidoo, L.

    2014-12-01

    The study reported a comparison between two Radarsat-2 polarimetric SAR (polSAR) images from extreme dry versus wet conditions are compared in an effort to determine the value of using polarimetric SAR data for estimating fuel moisture over South Africa savannahs and Alaska boreal forests. The savannahs study area is located into the Kruger National Park area and has 36 sites of lowveld savannas from bare overgrazed sites to medium-dense savannahs. The boreal forest study area has a chronosequence of black spruce ecosystems (recent burns, shrub-dominated regenerating forests , open canopied forests, moderately dense forest cover). Both study areas have a fairly level topography suitable for radar studies. The polSAR images were acquired using the same beam mode (FQ5 (23-25° incidence angle over the boreal sites, FQ15 (34.47-36.05° incidence angle) over the savannahs sites). Over each study area, soil moisture and vegetation structural data were measured in situ concurrently to the acquisition of the SAR imagery. The polSAR images were filtered for speckle noise using a Lee sigma filter and several polarimetric products were computed, such as those directly derived from the images (single linear and polairzed backscatters, polarimetric discriminators) and from target decompositions (Freeman-Durden, new van Zyl, Cloude-Pottier). Because most of these variables have a different unit, a normalized difference (in %) for each variable was calculated using the median values of the dry and wet dates for easier comparison of variable changes between the dates. Over both study areas, the normalized difference between wet and dry conditions was lower when higher tree canopy occurs. Results show utility of C-HH and C-RR polarized backscatters. Several polarimetric discriminators (dmin, Pr max, Pr min, Smax, Smin) were also significantly affected by the soil wetness. The Freeman Durden and van Zyl decomposition parameters outperformed the Cloude-Pottier decomposition

  5. China’s Strategy Toward South and Central Asia: An Empty Fortress

    DTIC Science & Technology

    2014-01-01

    Panda , “India’s Approach to Central Asia: Strategic Intent and Geo-political Calculus,” China and Eurasia Forum Quarterly, Vol. 7, No. 3, 2009, pp...calculus must include not just these countries but also India—the sprawling giant of South Asia. Western China, which includes not just Xinjiang but...according to a United Nations Department of Economic and Social Affairs report, the South Asian giant is poised to surpass the Middle Kingdom as the

  6. A 2000 year varve-based climate record from the central Brooks Range, Alaska

    SciTech Connect

    Bird, BW; Abbott, MB; Finney, BP; Kutchko, B

    2009-01-01

    Varved minerogenic sediments from glacial-fed Blue Lake, northern Alaska, are used to investigate late Holocene climate variability. Varve-thickness measurements track summer temperature recorded at Atigun Pass, located 41 km east at a similar elevation (r (2) = 0.31, P = 0.08). Results indicate that climate in the Brooks Range from 10 to 730 AD (varve year) was warm with precipitation inferred to be higher than during the twentieth century. The varvetemperature relationship for this period was likely compromised and not used in our temperature reconstruction because the glacier was greatly reduced, or absent, exposing sub-glacial sediments to erosion from enhanced precipitation. Varve-inferred summer temperatures and precipitation decreased after 730 AD, averaging 0.4A degrees C above the last millennial average (LMA = 4.2A degrees C) from 730 to 850 AD, and 0.1A degrees C above the LMA from 850 to 980 AD. Cooling culminated between 980 and 1030 AD with temperatures 0.7A degrees C below the LMA. Varve-inferred summer temperatures increased between 1030 and 1620 AD to the LMA, though the period between 1260 and 1350 AD was 0.2A degrees C below the LMA. Although there is no equivalent to the European Medieval Warm Period in the Blue Lake record, two warm intervals occurred from 1350 to 1450 AD and 1500 to 1620 AD (0.4 and 0.3A degrees C above the LMA, respectively). During the Little Ice Age (LIA; 1620 to 1880 AD), inferred summer temperature averaged 0.2A degrees C below the LMA. After 1880 AD, inferred summer temperature increased to 0.8A degrees C above the LMA, glaciers retreated, but aridity persisted based on a number of regional paleoclimate records. Despite warming and glacial retreat, varve thicknesses have not achieved pre-730 AD levels. This reflects limited sediment availability and transport due to a less extensive retreat compared to the first millennium, and continued relative aridity. Overall, the Blue Lake record is similar to varve records from the

  7. Stratigraphic framework of Holocene volcaniclastic deposits, Akutan Volcano, east-central Aleutian Islands, Alaska

    USGS Publications Warehouse

    Waythomas, C.F.

    1999-01-01

    Akutan Volcano is one of the most active volcanoes in the Aleutian arc, but until recently little was known about its history and eruptive character. Following a brief but sustained period of intense seismic activity in March 1996, the Alaska Volcano Observatory began investigating the geology of the volcano and evaluating potential volcanic hazards that could affect residents of Akutan Island. During these studies new information was obtained about the Holocene eruptive history of the volcano on the basis of stratigraphic studies of volcaniclastic deposits and radiocarbon dating of associated buried soils and peat. A black, scoria-bearing, lapilli tephra, informally named the 'Akutan tephra,' is up to 2 m thick and is found over most of the island, primarily east of the volcano summit. Six radiocarbon ages on the humic fraction of soil A-horizons beneath the tephra indicate that the Akutan tephra was erupted approximately 1611 years B.P. At several locations the Akutan tephra is within a conformable stratigraphic sequence of pyroclastic-flow and lahar deposits that are all part of the same eruptive sequence. The thickness, widespread distribution, and conformable stratigraphic association with overlying pyroclastic-flow and lahar deposits indicate that the Akutan tephra likely records a major eruption of Akutan Volcano that may have formed the present summit caldera. Noncohesive lahar and pyroclastic-flow deposits that predate the Akutan tephra occur in the major valleys that head on the volcano and are evidence for six to eight earlier Holocene eruptions. These eruptions were strombolian to subplinian events that generated limited amounts of tephra and small pyroclastic flows that extended only a few kilometers from the vent. The pyroclastic flows melted snow and ice on the volcano flanks and formed lahars that traveled several kilometers down broad, formerly glaciated valleys, reaching the coast as thin, watery, hyperconcentrated flows or water floods. Slightly

  8. Physical characteristics of stream subbasins in the Blue Earth River Basin, south-central Minnesota and north-central Iowa

    USGS Publications Warehouse

    Lorenz, D.L.; Payne, G.A.

    1992-01-01

    This report presents data describing the physical characteristics of stream basins upstream from selected points on streams in the Blue Earth River basin, located in south-central Minnesota and north-central Iowa. The physical characteristics are the drainage area of the basin, the percentage area of the basin covered only by lakes, the percentage area of the basin covered by both lakes and wetlands, the main-channel length, and the mainchannel slope. The points on the stream include outlets of subbasins of at least five square miles, outfalls of sewage treatment plants, and locations of U.S. Geological Survey gaging stations.

  9. Preliminary geology of eastern Umtanum Ridge, South-Central Washington

    SciTech Connect

    Goff, F.E.

    1981-01-01

    The basalt stratigraphy and geologic structures of eastern Umtanum Ridge have been mapped and studied in detail to help assess the feasibility of nuclear waste terminal storage on the Hanford Site in southeastern Washington State. Eastern Umtanum Ridge is an asymmetric east-west-trending anticline of Columbia River basalt that plunges 5 degrees eastward into the Pasco Basin. Geologic mapping and determination of natural remanent magnetic polarity and chemical composition reveal that flows of the Pomona and Umatilla Members (Saddle Mountains Basalt), Priest Rapids and Frenchman Springs Members (Wanapum Basalt), and Grande Ronde Basalt were erupted as fairly uniform sheets. The Wahluke and Huntzinger flows (Saddle Mountains Basalt) fill a paleovalley cut into Wanapum Basalt. No evidence was found to indicate Quaternary-age movement on any structures in the map area. The basalt strata on the south limb of the Umtanum anticline display relatively little tectonic deformation since Miocene-Pliocene time. Thus, the buried south flank of Umtanum Ridge may provide an excellent location for a nuclear waste repository beneath the Hanford Site.

  10. Central Heat and Power Plant Coal Dust and Silica Risk Management, Eielson Air Force Base, Alaska

    DTIC Science & Technology

    2014-12-11

    evaluation of potential ammonia exposures at the Eielson Air Force Base (EAFB) Central Heat and Power Plant (CHPP) following the installation of a new...boiler and emission controls. While the main purpose of the visit was an ammonia health risk assessment, the potential exposure to coal dust and...addition to the main ammonia health risk assessment letter and designed to inform EAFB of the status of the pending silica rule, exposure assessment

  11. Multistory duplexes with forward dipping roofs, north central Brooks Range, Alaska

    USGS Publications Warehouse

    Wallace, W.K.; Moore, T.E.; Plafker, G.

    1997-01-01

    The Endicott Mountains allochthon has been thrust far northward over the North Slope parautochthon in the northern Brooks Range. Progressively younger units are exposed northward within the allochthon. To the south, the incompetent Hunt Fork Shale has thickened internally by asymmetric folds and thrust faults. Northward, the competent Kanayut Conglomerate forms a duplex between a floor thrust in Hunt Fork and a roof thrust in the Kayak Shale. To the north, the competent Lisburne Group forms a duplex between a floor thrust in Kayak and a roof thrust in the Siksikpuk Formation. Both duplexes formed from north vergent detachment folds whose steep limbs were later truncated by south dipping thrust faults that only locally breach immediately overlying roof thrusts. Within the parautochthon, the Kayak, Lisburne, and Siksikpuk-equivalent Echooka Formation form a duplex identical to that in the allochthon. This duplex is succeeded abruptly northward by detachment folds in Lisburne. These folds are parasitic to an anticlinorium interpreted to reflect a fault-bend folded horse in North Slope "basement," with a roof thrust in Kayak and a floor thrust at depth. These structures constitute two northward tapered, internally deformed wedges that are juxtaposed at the base of the allochthon. Within each wedge, competent units have been shortened independently between detachments, located mainly in incompetent units. The basal detachment of each wedge cuts upsection forward (northward) to define a wedge geometry within which units dip regionally forward. These dips reflect forward decrease in internal structural thickening by forward vergent folds and hindward dipping thrust faults. Copyright 1997 by the American Geophysical Union.

  12. Multistory duplexes with forward dipping roofs, north central Brooks Range, Alaska

    NASA Astrophysics Data System (ADS)

    Wallace, Wesley K.; Moore, Thomas E.; Plafker, George

    1997-01-01

    The Endicott Mountains allochthon has been thrust far northward over the North Slope parautochthon in the northern Brooks Range. Progressively younger units are exposed northward within the allochthon. To the south, the incompetent Hunt Fork Shale has thickened internally by asymmetric folds and thrust faults. Northward, the competent Kanayut Conglomerate forms a duplex between a floor thrust in Hunt Fork and a roof thrust in the Kayak Shale. To the north, the competent Lisburne Group forms a duplex between a floor thrust in Kayak and a roof thrust in the Siksikpuk Formation. Both duplexes formed from north vergent detachment folds whose steep limbs were later truncated by south dipping thrust faults that only locally breach immediately overlying roof thrusts. Within the parautochthon, the Kayak, Lisburne, and Siksikpuk-equivalent Echooka Formation form a duplex identical to that in the allochthon. This duplex is succeeded abruptly northward by detachment folds in Lisburne. These folds are parasitic to an anticlinorium interpreted to reflect a fault-bend folded horse in North Slope "basement," with a roof thrust in Kayak and a floor thrust at depth/These structures constitute two northward tapered, internally deformed wedges that are juxtaposed at the base of the allochthon. Within each wedge, competent units have been shortened independently between detachments, located mainly in incompetent units. The basal detachment of each wedge cuts upsection forward (northward) to define a wedge geometry within which units dip regionally forward. These dips reflect forward decrease in internal structural thickening by forward vergent folds and hindward dipping thrust faults.

  13. Geologic Field Notes, Geochemical Analyses, and Field Photographs of Outcrops and Rock Samples from the Big Delta B-1 Quadrangle, East-Central Alaska

    USGS Publications Warehouse

    Day, Warren C.; O'Neill, J. Michael

    2008-01-01

    The U.S. Geological Survey, in cooperation with the Alaska Department of Natural Resources Division of Mining, Land, and Water, has released a geologic map of the Big Delta B-1 quadrangle of east-central Alaska (Day and others, 2007). This companion report presents the major element oxide and trace element geochemical analyses, including those for gold, silver, and base metals, for representative rock units and for grab samples from quartz veins and mineralized zones within the quadrangle. Also included are field station locations, field notes, structural data, and field photographs based primarily on observations by W.C. Day with additions by J.M. O'Neill and B.M. Gamble, all of the U.S. Geological Survey. The data are provided in both Microsoft Excel spread sheet format and as a Microsoft Access database.

  14. Whole-rock and sulfide-mineral geochemical data for samples from volcanogenic massive sulfide deposits of the Bonnifield district, east-central Alaska

    USGS Publications Warehouse

    Dusel-Bacon, Cynthia; Slack, John F.; Koenig, Alan E.; Foley, Nora K.; Oscarson, Robert L.; Gans, Kathleen D.

    2011-01-01

    This Open-File Report presents geochemical data for outcrop and drill-core samples from volcanogenic massive sulfide deposits and associated metaigneous and metasedimentary rocks in the Wood River area of the Bonnifield mining district, northern Alaska Range, east-central Alaska. The data consist of major- and trace-element whole-rock geochemical analyses, and major- and trace-element analyses of sulfide minerals determined by electron microprobe and laser ablation—inductively coupled plasma—mass spectrometry (LA-ICP-MS) techniques. The PDF consists of text, appendix explaining the analytical methods used for the analyses presented in the data tables, a sample location map, and seven data tables. The seven tables are also available as spreadsheets in several file formats. Descriptions and discussions of the Bonnifield deposits are given in Dusel-Bacon and others (2004, 2005, 2006, 2007, 2010).

  15. Late Cenozoic structure and stratigraphy of south-central Washington

    SciTech Connect

    Reidel, S.P. |; Campbell, N.P.; Fecht, K.R.; Lindsey, K.A.

    1993-09-01

    The structural framework of the Columbia Basin began developing before Columbia River Basalt Group (CRBG) volcanism. Prior to 17.5 Ma, the eastern part of the basin was a relatively stable area, with a basement of Paleozoic and older crystalline rock. The western part was an area of subsidence in which large volumes of sediment and volcanic rocks accumulated. Concurrent with eruption of the CRBG, anticlinal ridges of the Yakima Fold Belt (YFB) were growing under north-south compression. Topographic expression of these features was later masked by the large volume of CRBG basalt flowing west from fissures in the eastern Columbia Basin. The folds continued to develop after cessation of volcanism, leading to as much as 1,000 m of structural relief in the past 10 million years. Post-CRBG evolution of the Columbia Basin is recorded principally in folding and faulting in the YFB and sediments deposited in the basins. The accompanying tectonism resulted in lateral migration of major depositional systems into subsiding structural lows. Although known late Cenozoic faults are on anticlinal ridges, earthquake focal mechanisms and contemporary strain measurements indicate most stress release is occurring in the synclinal areas under north-south compression. There is no obvious correlation between focal mechanisms for earthquakes whose foci are in the CRBG and the location of known faults. High in situ stress values help to explain the occurrence of microseismicity in the Columbia Basin but not the pattern. Microseismicity appears to occur in unaltered fresh basalt. Faulted basalt associated with the YFB is highly brecciated and commonly altered to clay. The high stress, abundance of ground water in confined aquifers of the CRBG, and altered basalt in fault zones suggest that the frontal faults on the anticlinal ridges probably have some aseismic deformation. 85 refs.

  16. Lisburne Group (Mississippian-Lower Permian) petrography, paragenesis, and hydrocarbon potential, central Brooks Range, Alaska

    SciTech Connect

    Krutak, P.R.

    1989-03-01

    Subsurface Lisburne Group (Wahoo) rocks at Prudhoe Bay-Kuparuk fields produce 2 million bbl of oil/day and contain 2-3 billion bbl of oil in place. Lisburne reservoirs are early diagenetic dolomites encased in thick platform carbonates. Petrographic and geochemical study of 264 samples from eight newly discovered surface Lisburne sections comprising 4568 ft of strata in the Central Brooks Range provide new data concerning paragenesis and hydrocarbon potential of Lisburne facies farther west. A generalized paragenetic sequence for Lisburne equivalents of this region is (1) initial carbonate skeletal growth (both aragonite and calcite) during the Carboniferous, (2) subsequent recrystallization and inversion of aragonite to calcite, the change to calcite proceeding throughout late Paleozoic and Permian-Triassic time, (3) dolomitization in the Middle and Late Carboniferous, (4) chertification and silicification, postdating slightly or overlapping dolomitization, (5) development of porosity (moldic, intracrystal, etc.) in the middle to late Mesozoic, (6) formation of fracture porosity concurrent with the Brooks Range orogeny during Middle Jurassic-Cretaceous time, (7) oil generation, migration, and emplacement in Late Cretaceous-Tertiary time. Lisburne dolomites from the Central Brooks Range bear heavy hydrocarbons. Rock-Eval pyrolysis indicates part of the section is in the oil window and near the peak wet-gas generation zone. Shale samples from this region display thermal alteration indices and vitrinite reflectance values near the oil floor and also indicate potential for sourcing dry gas. Conodont color alteration indices show part of the Lisburn could produce dry gas.

  17. The last termination in the central South Atlantic

    NASA Astrophysics Data System (ADS)

    Ljung, Karl; Holmgren, Sofia; Kylander, Malin; Sjolte, Jesper; Van der Putten, Nathalie; Kageyama, Masa; Porter, Charles T.; Björck, Svante

    2015-09-01

    Lake sediments and peat deposits from two basins on Nightingale Island (37°S), in the Tristan da Cunha archipelago, South Atlantic, have been analyzed. The studies were focused on the time period 16.2-10.0 cal ka BP, determined by 36 14C dates from the two sequences. A wide variety of proxies were used, including pollen and diatom analyzes, biogenic silica content, C and N analyzes, stable isotopes (13C and 15N), elemental concentrations and magnetic susceptibility measurements, to detect environmental changes that can be related to shifts of the circulation belts of the Southern Ocean. In addition, climate model simulations were carried out. We find that the sediments are underlain by a >2 cal ka BP long hiatus, possibly representing a dried-out lake bed. The climate simulations corroborate that the area might have been exposed to arid conditions as a consequence of the Heinrich 1 event in the north and a southward displacement of the ITCZ. The development on the island after 16.2 cal ka BP is determined by the position of the Subtropical Front (STF) and the Southern Hemisphere Westerlies (SHW). The period 16.2-14.75 cal ka BP was characterized by varying influence from SHW and with STF situated south of Tristan da Cunha, ending with a humidity peak and cooler conditions. The stable conditions 14.7-14.1 cal ka BP with cool and fairly arid conditions imply that STF and SHW were both north of the islands during the first part of the Antarctic Cold Reversal. The most unstable period, 14.1-12.7 cal ka BP, indicates incessant latitudinal shifts of the zonal circulation, perhaps related to climate variability in the Northern Hemisphere and bipolar seesaw mechanisms as the strength of the Atlantic Meridional Overturning Circulation (AMOC) varied. At 12.7 cal ka BP the Holocene warming began with a gradually drier and warmer climate as a result of a dampened AMOC during the Younger Dryas cooling in the north with ITCZ, STF and SHW being displaced southwards. Peak warming

  18. Three-dimensional model of an ultramafic feeder system to the Nikolai Greenstone mafic large igneous province, central Alaska Range

    USGS Publications Warehouse

    Glen, J.M.G.; Schmidt, J.M.; Connard, G.G.

    2011-01-01

    The Amphitheater Mountains and southern central Alaska Range expose a thick sequence of Triassic Nikolai basalts that is underlain by several mafic-ultramafic complexes, the largest and best exposed being the Fish Lake and Tangle (FL-T) mafic-ultramafic sills that flank the Amphitheater Mountains synform. Three-dimensional (3-D) modeling of gravity and magnetic data reveals details of the structure of the Amphitheater Mountains, such as the orientation and thickness of Nikolai basalts, and the geometry of the FL-T intrusions. The 3-D model (50 ?? 70 km) includes the full geographic extent of the FL-T complexes and consists of 11 layers. Layer surfaces and properties (density and magnetic susceptibility) were modified by forward and inverse methods to reduce differences between the observed and calculated gravity and magnetic grids. The model suggests that the outcropping FL-T sills are apparently connected and traceable at depth and reveals variations in thickness, shape, and orientation of the ultramafic bodies that may identify paths of magma flow. The model shows that a significant volume (2000 km3) of ultramafic material occurs in the subsurface, gradually thickening and plunging westward to depths exceeding 4 km. This deep ultramafic material is interpreted as the top of a keel or root system that supplied magma to the Nikolai lavas and controlled emplacement of related magmatic intrusions. The presence of this deep, keel-like structure, and asymmetry of the synform, supports a sag basin model for development of the Amphitheater Mountains structure and reveals that the feeders to the Nikolai are much more extensive than previously known. Copyright 2011 by the American Geophysical Union.

  19. Detrital zircon geochronology of the Adams Argillite and Nation River Formation, east-central Alaska, U.S.A

    USGS Publications Warehouse

    Gehrels, G.E.; Johnsson, M.J.; Howell, D.G.

    1999-01-01

    The Cambrian Adams Argillite and the Devonian Nation River Formation are two sandstone-bearing units within a remarkably complete Paleozoic stratigraphic section in east-central Alaska. These strata, now foreshortened and fault-bounded, were originally contiguous with miogeoclinal strata to the east that formed as a passive-margin sequence along the northwestern margin of the North American continent. Seventy-five detrital zircon grains from the Adams Argillite and the Nation River Formation were analyzed in an effort to provide constraints on the original sources of the grains, and to generate a detrital zircon reference for miogeoclinal strata in the northern Cordillera. Thirty-five single zircon grains from a quartzite in the Adams Argillite yield dominant age clusters of 1047-1094 (n = 6), 1801-1868 (n = 10), and 2564-2687 (n = 5) Ma. Forty zircons extracted from a sandstone in the Nation River Formation yield clusters primarily of 424-434 (n = 6), 1815-1838 (n = 6), 1874-1921 (n = 7), and 2653-2771 (n = 4) Ma. The Early Proterozoic and Archean grains in both units probably originated in basement rocks in a broad region of the Canadian Shield. In contrast, the original igneous sources for mid-Protcrozoic grains in the Adams Argillite and ??? 430 Ma grains in the Nation River Formation are more difficult to identify. Possible original sources for the mid-Proterozoic grains include: (1) the Grenville Province of eastern Laurentia, (2) the Pearya terrane along the Arctic margin, and (3) mid-Proterozoic igneous rocks that may have been widespread along or outboard of the Cordilleran margin. The ??? 430 Ma grains may have originated in: (1) arc-type sources along the Cordilleran margin, (2) the Caledonian orogen, or (3) a landmass, such as Pearya, Siberia, or crustal fragments now in northern Asia, that resided outboard of the Innuitian orogen during mid-Paleozoic time. Copyright ?? 1999, SEPM (Society for Sedimentary Geology).

  20. Imaging the transition from Aleutian subduction to Yakutat collision in central Alaska, with local earthquakes and active source data

    USGS Publications Warehouse

    Eberhart-Phillips, D.; Christensen, D.H.; Brocher, T.M.; Hansen, R.; Ruppert, N.A.; Haeussler, P.J.; Abers, G.A.

    2006-01-01

    In southern and central Alaska the subduction and active volcanism of the Aleutian subduction zone give way to a broad plate boundary zone with mountain building and strike-slip faulting, where the Yakutat terrane joins the subducting Pacific plate. The interplay of these tectonic elements can be best understood by considering the entire region in three dimensions. We image three-dimensional seismic velocity using abundant local earthquakes, supplemented by active source data. Crustal low-velocity correlates with basins. The Denali fault zone is a dominant feature with a change in crustal thickness across the fault. A relatively high-velocity subducted slab and a low-velocity mantle wedge are observed, and high Vp/Vs beneath the active volcanic systems, which indicates focusing of partial melt. North of Cook Inlet, the subducted Yakutat slab is characterized by a thick low-velocity, high-Vp/Vs, crust. High-velocity material above the Yakutat slab may represent a residual older slab, which inhibits vertical flow of Yakutat subduction fluids. Alternate lateral flow allows Yakutat subduction fluids to contribute to Cook Inlet volcanism and the Wrangell volcanic field. The apparent northeast edge of the subducted Yakutat slab is southwest of the Wrangell volcanics, which have adakitic composition consistent with melting of this Yakutat slab edge. In the mantle, the Yakutat slab is subducting with the Pacific plate, while at shallower depths the Yakutat slab overthrusts the shallow Pacific plate along the Transition fault. This region of crustal doubling within the shallow slab is associated with extremely strong plate coupling and the primary asperity of the Mw 9.2 great 1964 earthquake. Copyright 2006 by the American Geophysical Union.

  1. Spatial and temporal variation in physicochemical properties of dairy lagoons in south-central Idaho

    Technology Transfer Automated Retrieval System (TEKTRAN)

    There are large quantities of wastewater generated on dairies in south-central Idaho, which can be a source of valuable nutrients as well contribute to air quality and climate change issues via ammonia (NH3) and greenhouse gas (GHG) emissions. The objective of this study was to examine the range of ...

  2. How to decide intervention thresholds based on FRAX in central south Chinese postmenopausal women.

    PubMed

    Zhang, Zhimin; Ou, Yangna; Sheng, Zhifeng; Liao, Eryuan

    2014-03-01

    The FRAX tool has been used to determine possible thresholds for therapeutic intervention; however, there are no FRAX-based intervention thresholds available for China, we proposed that the 10-year probability of major osteoporotic fracture and hip fracture of about 4.0 and 1.3%, respectively, may be acceptable intervention thresholds for central south Chinese postmenopausal women.

  3. PROCSEE: Policy Challenges for Professional Higher Education in Central and South-Eastern Europe

    ERIC Educational Resources Information Center

    Policnik, Jasmina; Sauli Miklavcic, Alicia Leonor; Alupei-Durach, Flavia; Nožica, Žarko; Chrást, Ondrej; Voldánová, Iva; Karpíšek, Michal; Dinya, László; Medve, Anna; Wéber, György; Racsko, Réka; Perényi, Petra; Camilleri, Anthony F.

    2016-01-01

    PROCSEE is a policy-oriented project, aimed at strengthening the provision of professional higher education, by strengthening the policy-work conducted by umbrella organizations representing professional higher education institutions in Central and South-Eastern in Europe. Working together over three years, the project intends to: (1) identify the…

  4. 77 FR 64316 - Endangered and Threatened Species; Recovery Plan South-Central California Coast Steelhead...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-19

    ... Plan South-Central California Coast Steelhead Distinct Population Segment AGENCY: National Marine...) (Oncorhynchus mykiss) Distinct Population (DPS). NMFS is soliciting review and comment from the public and all... soliciting relevant information on SCCC Steelhead DPS populations and their freshwater/marine habitats....

  5. Steelhead of the south-central/southern California coast: Population characterization for recovery planning

    USGS Publications Warehouse

    Boughton, David A.; Adams, P.B.; Anderson, E.; Fusaro, Craig; Keller, E.; Kelley, Elsie; Lentsch, Leo; Nielsen, J. L.; Perry, Katie; Regan, Helen; Swift, C.; Watson, Fred

    2006-01-01

    This report by the National Marine Fisheries Service applies a formal evaluation framework to the problem of delineating Oncorhynchus mykiss populations in the South-Central/Southern California Coast recovery domain, in support of recovery planning under the Endangered Species Act.

  6. 40 CFR 81.105 - South Central Pennsylvania Intrastate Air Quality Control Region.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) DESIGNATION OF AREAS FOR AIR QUALITY PLANNING PURPOSES... Region. The South Central Pennsylvania Intrastate Air Quality Control Region consists of the territorial... territorial area of all municipalities (as defined in section 302(f) of the Clean Air Act, 42 U.S.C....

  7. 40 CFR 81.105 - South Central Pennsylvania Intrastate Air Quality Control Region.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) DESIGNATION OF AREAS FOR AIR QUALITY PLANNING PURPOSES... Region. The South Central Pennsylvania Intrastate Air Quality Control Region consists of the territorial... territorial area of all municipalities (as defined in section 302(f) of the Clean Air Act, 42 U.S.C....

  8. Likely Autochthonous Transmission of Trypanosoma cruzi to Humans, South Central Texas, USA

    PubMed Central

    Gunter, Sarah M.; Murray, Kristy O.; Gorchakov, Rodion; Beddard, Rachel; Rossmann, Susan N.; Montgomery, Susan P.; Rivera, Hilda; Brown, Eric L.; Aguilar, David; Widman, Lawrence E.

    2017-01-01

    Chagas disease, caused by Trypanosoma cruzi, is a major neglected tropical disease affecting the Americas. The epidemiology of this disease in the United States is incomplete. We report evidence of likely autochthonous vectorborne transmission of T. cruzi and health outcomes in T. cruzi–seropositive blood donors in south central Texas, USA. PMID:28221110

  9. Looking south through east portion of Centralized Work Equipment (C.W.E.) ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Looking south through east portion of Centralized Work Equipment (C.W.E.) Storage Shed (Bldg. 126). Note overhead monorails for material-handling hoists. This shed stored track maintenance materials - Atchison, Topeka, Santa Fe Railroad, Albuquerque Shops, C.W.E. Storage Shed, 908 Second Street, Southwest, Albuquerque, Bernalillo County, NM

  10. Spiculitic chert reservoir in Glick Field, South-Central Kansas

    SciTech Connect

    Rogers, J.P.; Longman, M.W.; Lloyd, R.M.

    1995-01-01

    Glick Field, located in Kiowa and Comanche counties of southern Kansas, was discovered in 1957 and has produced more than 362 BCF from Mississippian Osage chert, commonly referred to as the {open_quotes}Chat.{close_quotes} Other {open_quotes}CHAT{close_quotes} reservoirs in Kansas and Oklahoma produce mainly from mixed chert and dolomite beneath the pre-Pennsylvanian unconformity, but Glick Field`s reservoir is dominated by chert containing abundant sponge spicules. Glick Field is a stratigraphic trap with production ending where the spiculitic facies pinches out into tight limestones to the south and west which provide a lateral seal. Additionally, updip, to the northeast, the productive facies is truncated by the unconformity. Reworked chert conglomerates overlying the spiculitic reservoir at the unconformity also produce some gas. The spiculitic chert forming the reservoir was desposited below storm wavebase and grades laterally in all directions into echinoderm and brachiopod-rich skeletal wackestones and lime mudstones. Even where completely silicified, these associated limestone are tight. Thus, the reservoir is an in situ oval-shaped complex of internally brecciated sponge mats and bioherms capped in part by the chert conglomerate. The spiculitic chert contains up to 50% porosity in molds after sponge spicules, matrix micropores and vugs are connected in part by fracture and breccia porosity. Distribution of the sponge bioherms which form the reservoir facies was partly controlled by a subtle change on the shallow Mississippian carbonate shelf from clean skeletal limestones southward into shaly (and probably more anoxic) carbonates known locally as the {open_quotes}Cowley Facies.{close_quotes} The sponge bioherms formed most commonly just updip from this boundary, which can be mapped across southern Kansas. Thus, lithologic mapping provides a potential exploration tool with which to find other stratigraphically trapped spiculitic reservoirs in the area.

  11. Modeling the mass balance of the Wolverine Glacier Alaska USA using the PTAA model

    NASA Astrophysics Data System (ADS)

    Korn, D.

    2010-12-01

    Glaciers in Alaska have been increasingly losing mass over the last several decades. This trend is especially apparent in South-Central Alaska where many glaciers are undergoing rapid changes and contributing substantially to rising sea levels (Arendt et al., 2002). It is important to understand the rates at which these glaciers are losing mass as well as the important climatic drivers to better prepare for what the future holds in this region and the rest of the world. This work compares glacier mass balance data modeled through the Precipitation-Temperature Area Altitude (PTAA) mass balance model for the Wolverine Glacier in the Kenai Peninsula in South-Central Alaska to observed data from the USGS “benchmark” glacier program in order to help validate the model. The mass balance data are also correlated with climate data in order to understand the main climatic drivers of the glacier mass balance in this region.

  12. Molecular phylogeny of Trypanosoma cruzi from Central America (Guatemala) and a comparison with South American strains.

    PubMed

    Iwagami, M; Higo, H; Miura, S; Yanagi, T; Tada, I; Kano, S; Agatsuma, T

    2007-12-01

    Molecular phylogenetic analysis was carried out for 21 strains of Trypanosoma cruzi, nine of which were obtained from Guatemala and 12 from South America. Phylogenetic trees were constructed using the nucleotide sequences of two nuclear gene regions, dihydrofolate reductase-thymidylate synthase (DHFR-TS) and trypanothione reductase (TR), and contiguous portions of two mitochondrial genes, cytochrome oxidase subunit II (COII) and reduced nicotinamide adenine dinucleotide dehydrogenase subunit 1 (ND1). Possible genetic exchange between the rather divergent lineages of T. cruzi II from South America was suggested in the trees of the two nuclear genes. T. cruzi I strains obtained from Guatemala and Colombia were identical in all the genes examined, but other T. cruzi I isolates from South America were rather polymorphic in the DHFR-TS and mitochondrial genes. No genetic exchange was identified between T. cruzi I populations from Central and South America in the present study.

  13. Lateral continuity of the Blarney Creek Thrust, Doonerak Windown, Central Brooks Range, Alaska

    SciTech Connect

    Seidensticker, C.M.; Julian, F.E.; Phelps, J.C.; Oldow, J.S.; Avellemant, H.G.

    1985-04-01

    The contact between Carboniferous and lower Paleozoic rocks, exposed along the northern margin of the Doonerak window in the central Brooks Range, is a major thrust fault called the Blarney Creek thrust (BCT). The BCT has been traced over a distance of 25 km, from Falsoola Mountain to Wien Mountain. The tectonic nature of this contact is demonstrated by: (1) omission of stratigraphic units above and below the BCT; (2) large angular discordance in orientation of first-generation cleavage at the BCT; (3) numerous thrust imbricates developed in the upper-plate Carboniferous section that sole into the BCT; and (4) truncation of an upper-plate graben structure at the BCT. Lack of evidence for pre-Carboniferous deformation in the lower plate casts doubt on the interpretation of the contact as an angular unconformity. However, the localized presence below the BCT of Mississippian Kekiktuk Conglomerate and Kayak Shale, in apparent depositional contact with lower Paleozoic rocks, suggests that the BCT follows an originally disconformable contact between the Carboniferous and lower Paleozoic rocks. The juxtaposition of younger over older rocks at the BCT is explained by calling upon the BCT to act as the upper detachment surface of a duplex structure. Duplex development involves initial imbrication of the Carboniferous section using the BCT as a basal decollement, followed by formation of deeper thrusts in the lower Paleozoic section, which ramp up and merge into the BCT.

  14. High prevalence of cardiovascular disease in South Asians: Central role for brown adipose tissue?

    PubMed

    Boon, Mariëtte R; Bakker, Leontine E H; van der Linden, Rianne A D; van Ouwerkerk, Antoinette F; de Goeje, Pauline L; Counotte, Jacqueline; Jazet, Ingrid M; Rensen, Patrick C N

    2015-01-01

    Cardiovascular disease (CVD) is the leading cause of death in modern society. Interestingly, the risk of developing CVD varies between different ethnic groups. A particularly high risk is faced by South Asians, representing over one-fifth of the world's population. Here, we review potential factors contributing to the increased cardiovascular risk in the South Asian population and discuss novel therapeutic strategies based on recent insights. In South Asians, classical ('metabolic') risk factors associated with CVD are highly prevalent and include central obesity, insulin resistance, type 2 diabetes, and dyslipidemia. A contributing factor that may underlie the development of this disadvantageous metabolic phenotype is the presence of a lower amount of brown adipose tissue (BAT) in South Asian subjects, resulting in lower energy expenditure and lower lipid oxidation and glucose uptake. As it has been established that the increased prevalence of classical risk factors in South Asians cannot fully explain their increased risk for CVD, other non-classical risk factors must underlie this residual risk. In South Asians, the prevalence of "inflammatory" risk factors including visceral adipose tissue inflammation, endothelial dysfunction, and HDL dysfunction are higher compared with Caucasians. We conclude that a potential novel therapy to lower CVD risk in the South Asian population is to enhance BAT volume or its activity in order to diminish classical risk factors. Furthermore, anti-inflammatory therapy may lower non-classical risk factors in this population and the combination of both strategies may be especially effective.

  15. Multiethnicity, pluralism, and migration in the south central Andes: An alternate path to state expansion

    PubMed Central

    Goldstein, Paul S.

    2015-01-01

    The south central Andes is known as a region of enduring multiethnic diversity, yet it is also the cradle of one the South America’s first successful expansive-state societies. Social structures that encouraged the maintenance of separate identities among coexistent ethnic groups may explain this apparent contradiction. Although the early expansion of the Tiwanaku state (A.D. 600–1000) is often interpreted according to a centralized model derived from Old World precedents, recent archaeological research suggests a reappraisal of the socio-political organization of Tiwanaku civilization, both for the diversity of social entities within its core region and for the multiple agencies behind its wider program of agropastoral colonization. Tiwanaku’s sociopolitical pluralism in both its homeland and colonies tempers some of archaeology’s global assumptions about the predominant role of centralized institutions in archaic states. PMID:26195732

  16. Multiethnicity, pluralism, and migration in the south central Andes: An alternate path to state expansion.

    PubMed

    Goldstein, Paul S

    2015-07-28

    The south central Andes is known as a region of enduring multiethnic diversity, yet it is also the cradle of one the South America's first successful expansive-state societies. Social structures that encouraged the maintenance of separate identities among coexistent ethnic groups may explain this apparent contradiction. Although the early expansion of the Tiwanaku state (A.D. 600-1000) is often interpreted according to a centralized model derived from Old World precedents, recent archaeological research suggests a reappraisal of the socio-political organization of Tiwanaku civilization, both for the diversity of social entities within its core region and for the multiple agencies behind its wider program of agropastoral colonization. Tiwanaku's sociopolitical pluralism in both its homeland and colonies tempers some of archaeology's global assumptions about the predominant role of centralized institutions in archaic states.

  17. Hydrology of the San Luis Valley, south-central Colorado

    USGS Publications Warehouse

    Emery, P.A.; Boettcher, A.J.; Snipes, R.J.; Mcintyre, H.J.

    1969-01-01

    An investigation of the water resources of the Colorado part of the San Luis Valley was begun in 1966 by the U.S. Geological Survey, in cooperation with the Colorado Water Conservation Board. (See index map, fig. 1). The purpose of the investigation is to provide information for planning and implementing improved water-development and management practices. The major water problems in the San Luis Valley include (1) waterlogging, (2) waste of water by nonbeneficial evapotranspiration, (3) deterioration of ground-water chemical quality, and (4) failure of Colorado to deliver water to New Mexico and Texas in accordance with the Rio Grande Compact. This report describes the hydrologic environment, extent of water-resource development, and some of the problems related to that development. Information presented is based on data collected from 1966 to 1968 and on previous studies. Subsequent reports are planned as the investigation progresses. The San Luis Valley extends about 100 miles from Poncha Pass near the northeast corner of Saguache County, Colo., to a point about 16 miles south of the Colorado-New Mexico State line. The total area is 3,125 square miles, of which about 3,000 are in Colorado. The valley is nearly flat except for the San Luis Hills and a few other small areas. The Colorado part of the San Luis Valley, which is described in this report, has an average altitude of about 7,700 feet. Bounding the valley on the west are the San Juan Mountains and on the east the Sangre de Cristo Mountains. Most of the valley floor is bordered by alluvial fans deposited by streams originating in the mountains, the most extensive being the Rio Grande fan (see block diagram, fig. 2 in pocket). Most of the streamflow is derived from snowmelt from 4,700 square miles of watershed in the surrounding mountains. The northern half of the San Luis Valley is internally drained and is referred to as the closed basin. The lowest part of this area is known locally as the "sump." The

  18. Microclimate, Water Potential, Transpiration, and Bole Dielectric Constant of Coniferous and Deciduous Tree Species in the Continental Boreal Ecotone of Central Alaska

    NASA Technical Reports Server (NTRS)

    Zimmermann, R.; McDonald, K.; Way, J.; Oren, R.

    1994-01-01

    Tree canopy microclimate, xylem water flux and xylem dielectric constant have been monitored in situ since June 1993 in two adjacent natural forest stands in central Alaska. The deciduous stand represents a mature balsam poplar site on the Tanana River floodplain, while the coniferous stand consists of mature white spruce with some black spruce mixed in. During solstice in June and later in summer, diurnal changes of xylem water potential were measured to investigate the occurrence and magnitude of tree transpiration and dielectric constant changes in stems.

  19. Spatial data for Eurycea salamander habitats associated With three aquifers in south-central Texas

    USGS Publications Warehouse

    Heitmuller, Franklin T.; Reece, Brian D.

    2006-01-01

    Eurycea salamander taxa comprise 12 known species that inhabit springs and caves in south-central Texas. Many of these are threatened or endangered species, and some are found only at one location. A number of the neotenic salamanders might be at risk from habitat loss associated with declines in ground-water levels. Eurycea salamander habitats are associated with three aquifers in south-central Texas: (1) the Edwards-Trinity (Plateau) aquifer, (2) the Edwards (Balcones Fault Zone) aquifer, and (3) the Trinity aquifer. The Edwards (Balcones fault zone) aquifer is commonly separated into three segments: from southwest to northeast, the San Antonio segment, the Barton Springs segment, and the northern segment. The Trinity aquifer south of the Colorado River can be divided into three permeable zones, the upper, middle, and lower zone. The U.S. Geological Survey, in cooperation with the U.S. Fish and Wildlife Service, developed this report (geodatabase) to aggregate the spatial data necessary to assess the potential effects of ground-water declines on known Eurycea habitat locations in south-central Texas. The geodatabase provides information about spring habitats, spring flow, cave habitats, aquifers, and projected water levels.

  20. Palaeomagnetism of lower cretaceous tuffs from Yukon-Kuskokwim delta region, western Alaska

    USGS Publications Warehouse

    Globerman, B.R.; Coe, R.S.; Hoare, J.M.; Decker, J.

    1983-01-01

    During the past decade, the prescient arguments1-3 for the allochthoneity of large portions of southern Alaska have been corroborated by detailed geological and palaeomagnetic studies in south-central Alaska 4-9 the Alaska Peninsula10, Kodiak Island11,12 and the Prince William Sound area13 (Fig. 1). These investigations have demonstrated sizeable northward displacements for rocks of late Palaeozoic, Mesozoic, and early Tertiary age in those regions, with northward motion at times culminating in collision of the allochthonous terranes against the backstop of 'nuclear' Alaska14,15. A fundamental question is which parts of Alaska underwent significantly less latitudinal translation relative to the 'stable' North American continent, thereby serving as the 'accretionary nucleus' into which the displaced 'microplates'16 were eventually incorporated17,18? Here we present new palaeomagnetic results from tuffs and associated volcaniclastic rocks of early Cretaceous age from the Yukon-Kuskokwin delta region in western Alaska. These rocks were probably overprinted during the Cretaceous long normal polarity interval, although a remagnetization event as recent as Palaeocene cannot be ruled out. This overprint direction is not appreciably discordant from the expected late Cretaceous direction for cratonal North America. The implied absence of appreciable northward displacement for this region is consistent with the general late Mesozoic-early Tertiary tectonic pattern for Alaska, based on more definitive studies: little to no poleward displacement for central Alaska, though substantially more northward drift for the 'southern Alaska terranes' (comprising Alaska Peninsula, Kodiak Island, Prince William Sound area, and Matunuska Valley) since late Cretaceous to Palaeocene time. ?? 1983 Nature Publishing Group.

  1. Early development of the south Central American margin: mechanisms and tectonic implications

    NASA Astrophysics Data System (ADS)

    Buchs, D. M.; Baumgartner, P. O.; Arculus, R.; Montes, C.; Bayona, G.; Cardona, A.

    2012-04-01

    The south Central American margin forms the SW border of the Caribbean Plate on top of the subducting Cocos and Nazca Plates between Nicaragua and Colombia. New and previous tectonostratigraphic, age and geochemical results show that the forearc basement between south Costa Rica and east Panama is composed of autochthonous and accreted sequences that provide important constraints on the development of the south Central American margin, the evolution of the Caribbean Plate and the formation of an inter-American land bridge. Autochtonous sequences in the forearc include three tectonostratigraphic units that occur at a regional scale: (1) a Late Cretaceous oceanic plateau considered to represent an extension of the Caribbean Large Igneous Province (CLIP) at the base of the arc; (2) Late Campanian to Maastrichtian protoarc sequences that cover or intrude the oceanic plateau; and (3) Maastrichtian to Eocene sequences of a more mature volcanic arc that overlies or intrude preceding units. These units clearly indicate that subduction initiation along the margin and, thus, the birth of the Caribbean Plate occurred in the Campanian. Incipient subduction was possibly triggered or facilitated by contrasted lithospheric strength across the edge of the CLIP and collision between the CLIP and South America during westward migration of South America. Accreted sequences in the forearc include mostly Late Cretaceous to Eocene seamount fragments between south Costa Rica and west Panama, with additional Eocene to Miocene olistostromal and hemipelagic sediments in south Costa Rica. The age and tectonostratigraphic relationships of accreted sequences, autochtonous sequences, and overlying forearc slope sediment suggest that subduction erosion, punctuated by local seamount or sediment accretion was the dominant process controlling the evolution of the outer margin at least until the Miocene. A major tectonic event affected the margin in the Middle Eocene, which is indicated by a

  2. Forest Fires Produce Dense Smoke over Alaska

    NASA Technical Reports Server (NTRS)

    2005-01-01

    On August 14, 2005, the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Terra satellite captured this stunning image of forest fires raging across the width of Alaska. Smoke from scores of fires (marked in red) filled the state's broad central valley and poured out to sea. Hemmed in by mountains to the north and the south, the smoke spreads westward and spills out over the Bering and Chukchi Seas (image left). More than a hundred fires were burning across the state as of August 14. Air quality warnings have been issued for about 90 percent of the Interior, according to the August 12 report from the Alaska Department of Environmental Conservation's Division of Air Quality. Conditions have ranged from 'very unhealthy' to 'hazardous' over the weekend in many locations, including Fairbanks. A large area of high atmospheric pressure spread over much of the state, keeping temperatures high and reducing winds that would clear the air.

  3. Can We Mitigate Climate Extremes using Managed Aquifer Recharge: Case Studies California Central Valley and South-Central Arizona, USA

    NASA Astrophysics Data System (ADS)

    Scanlon, B. R.; Reedy, R. C.; Faunt, C. C.; Pool, D. R.; Uhlman, K.

    2015-12-01

    Frequent long-term droughts interspersed with intense floods in the southwestern U.S. underscore the need to store more water to manage these climate extremes. Here we show how managed aquifer recharge can enhance drought resilience in the southwestern U.S. with ~ 70% of California under extreme drought and 75% of Arizona under moderate drought. Data on water sources, transportation, and users were compiled for managed aquifer recharge systems in the Central Valley and south-central Arizona. Groundwater depletion of 115 to 145 km3 in the 1900s created large subsurface reservoirs in thick alluvial basins in these regions. Large canals and aqueducts up to several 100 km long allow water to be imported from reservoirs, mostly in more humid regions. Imported water is either used instead of groundwater or is applied in surface spreading basins primarily during wet periods (≤1.3 km3/yr Central Valley, ≤0.7 km3/yr Arizona) and is extracted during droughts. The dominant water users include irrigators and municipalities both within and outside the managed aquifer recharge systems. Groundwater modeling indicates that recharge basins significantly increase groundwater storage in the Central Valley. Managed aquifer recharge systems significantly enhance drought resilience and increase sustainability of water resources in semiarid regions, complementing surface water reservoirs and conjunctive surface water/groundwater use by providing longer term storage.

  4. 78 FR 35957 - Notice of Intent To Prepare a Resource Management Plan for the Central Yukon Planning Area Alaska...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-14

    ... Framework Plan. Additionally, the RMP will cover lands in the Fairbanks North Star Borough that are... mining on fish and aquatic habitats; opening lands to new mineral entry; disposal of mineral material... governments; 7. The BLM will consider Department of the Interior guidance, Alaska Department of Fish and...

  5. Infectious etiologies of acute febrile illness among patients seeking health care in south-central Cambodia.

    PubMed

    Kasper, Matthew R; Blair, Patrick J; Touch, Sok; Sokhal, Buth; Yasuda, Chadwick Y; Williams, Maya; Richards, Allen L; Burgess, Timothy H; Wierzba, Thomas F; Putnam, Shannon D

    2012-02-01

    The agents of human febrile illness can vary by region and country suggesting that diagnosis, treatment, and control programs need to be based on a methodical evaluation of area-specific etiologies. From December 2006 to December 2009, 9,997 individuals presenting with acute febrile illness at nine health care clinics in south-central Cambodia were enrolled in a study to elucidate the etiologies. Upon enrollment, respiratory specimens, whole blood, and serum were collected. Testing was performed for viral, bacterial, and parasitic pathogens. Etiologies were identified in 38.0% of patients. Influenza was the most frequent pathogen, followed by dengue, malaria, and bacterial pathogens isolated from blood culture. In addition, 3.5% of enrolled patients were infected with more than one pathogen. Our data provide the first systematic assessment of the etiologies of acute febrile illness in south-central Cambodia. Data from syndromic-based surveillance studies can help guide public health responses in developing nations.

  6. Contextualizing the Trauma Experience of Women Immigrants From Central America, South America, and Mexico

    PubMed Central

    Kaltman, Stacey; de Mendoza, Alejandra Hurtado; Gonzales, Felisa A.; Serrano, Adriana; Guarnaccia, Peter J.

    2012-01-01

    Trauma has been understudied among Latina immigrants from Central and South America. This study examined the types and context of trauma exposure experienced by immigrant women from Central America, South America, and Mexico living in the United States. Twenty-eight women seeking care in primary care or social service settings completed life history interviews. The majority of the women reported some type of trauma exposure in their countries of origin, during immigration, and/or in the United States. In the interviews, we identified types of trauma important to the experience of these immigrants that are not queried by trauma assessments typically used in the United States. We also identified factors that are likely to amplify the impact of trauma exposure. The study highlights the importance of utilizing a contextualized approach when assessing trauma exposure among immigrant women. PMID:22144133

  7. Assessment of undiscovered oil and gas resources in Central and South America

    USGS Publications Warehouse

    ,

    2001-01-01

    The U.S. Geological Survey recently completed an assessment of undiscovered conventional oil and gas resources in 130 selected petroleum provinces of the world (USGS, 2000). Of these 130 provinces, 23 are in South America, Central America, and the Caribbean area (fig. 1). The assessed provinces range from established petroleum provinces with long histories of production such as the Maracaibo Basin to frontier provinces with little or no petroleum production such as the Guyana-Suriname Basin. Not all provinces with historic production or potential production were assessed for the USGS 2000 Assessment. At present we are assessing many of the remaining oil and gas provinces in Central and South America. In each province we (1) geologically defined total petroleum systems, (2) defined assessment units within total petroleum systems, and (3) assessed the volume of undiscovered conventional oil and gas in each assessment unit. We defined 26 total petroleum systems and 55 assessment units in the 23 provinces. 

  8. Genetic Diversity of the Ring-Tailed Lemur (Lemur catta) in South-Central Madagascar.

    PubMed

    Clarke, Tara A; Gray, Olivia; Gould, Lisa; Burrell, Andrew S

    2015-01-01

    Madagascar's lemurs, now deemed the most endangered group of mammals, represent the highest primate conservation priority in the world. Due to anthropogenic disturbances, an estimated 10% of Malagasy forest cover remains. The endangered Lemur catta is endemic to the southern regions of Madagascar and now occupies primarily fragmented forest habitats. We examined the influence of habitat fragmentation and isolation on the genetic diversity of L. catta across 3 different forest fragments in south-central Madagascar. Our analysis revealed moderate levels of genetic diversity. Genetic differentiation among the sites ranged from 0.05 to 0.11. These data suggest that the L. catta populations within south-central Madagascar have not yet lost significant genetic variation. However, due to ongoing anthropogenic threats faced by ring-tailed lemurs, continued conservation and research initiatives are imperative for long-term viability of the species.

  9. Geographic variation in age, growth and size structure of Percilia irwini from south-central Chile.

    PubMed

    Aedo, J R; Belk, M C; Habit, E M

    2009-01-01

    Percilia irwini from the Andalién and Biobío River basins of south-central Chile exhibited a mean age of 1.4 years with a maximum age of 4 years. Size at age differed among river zones and males were 10% larger than females at all ages. Compared to other locations, populations of P. irwini inhabiting areas subject to industrial and domestic effluents exhibited smaller size structure.

  10. Traditional use of medicinal plants in south-central Zimbabwe: review and perspectives

    PubMed Central

    2013-01-01

    Background Traditional medicine has remained as the most affordable and easily accessible source of treatment in the primary healthcare system of resource poor communities in Zimbabwe. The local people have a long history of traditional plant usage for medicinal purposes. Despite the increasing acceptance of traditional medicine in Zimbabwe, this rich indigenous knowledge is not adequately documented. Documentation of plants used as traditional medicines is needed so that the knowledge can be preserved and the utilized plants conserved and used sustainably. The primary objective of this paper is to summarize information on traditional uses of medicinal plants in south-central Zimbabwe, identifying research gaps and suggesting perspectives for future research. Methods This study is based on a review of the literature published in scientific journals, books, reports from national, regional and international organizations, theses, conference papers and other grey materials. Results A total of 93 medicinal plant species representing 41 families and 77 genera are used in south-central Zimbabwe. These plant species are used to treat 18 diseases and disorder categories, with the highest number of species used for gastro-intestinal disorders, followed by sexually transmitted infections, cold, cough and sore throat and gynaecological problems. Shrubs and trees (38% each) were the primary sources of medicinal plants, followed by herbs (21%) and climbers (3%). The therapeutic claims made on medicinal plants documented in south-central Zimbabwe are well supported by literature, with 82.8% of the plant species having similar applications in other regions of Zimbabwe as well as other parts of the world and 89.2% having documented biological and pharmacological properties. Conclusion This study illustrates the importance of traditional medicines in the treatment and management of human diseases and ailments in south-central Zimbabwe. Traditional medicines still play an important

  11. Notes on the distribution of eastern woodrats and hispid cotton rats in south-central Nebraska

    USGS Publications Warehouse

    Wills, H.D.; Geluso, Keith; Smits, E.J.; Springer, J.T.; Newton, W.E.

    2011-01-01

    The eastern woodrat (Neotoma floridana) and hispid cotton rat (Sigmodon hispidus) reach distributional limits in southern Nebraska (Jones 1964, Farney 1975). In the last half century, both species have expanded their distributional ranges in the region (Kugler and Geluso 2009, Wright et al. 2010). Herein, we report new localities of occurrence for both species that extend known distributional boundaries in south-central Nebraska beyond those reported by Kugler and Geluso (2009) and Wright et al. (2010).

  12. A new Starlight Reserve for the central South Island of New Zealand

    NASA Astrophysics Data System (ADS)

    Hearnshaw, John

    2015-03-01

    The Aoraki Mackenzie International Dark Sky Reserve is a new reserve created in 2012 by the International Dark-Sky Association in the central South Island of New Zealand, and covers over 4300 square kilometres around Mt John University Observatory. It is the first such reserve to be recognized at gold tier level and is the largest dark sky reserve in the world. Astro-tourism in the new reserve will be a prominent activity in the coming years.

  13. Selected water-quality data for the Minidoka Irrigation District, south-central Idaho, June 1987

    USGS Publications Warehouse

    Young, H.W.; Parliman, D.J.; O'Dell, I.

    1987-01-01

    This map report presents June 1987 water-quality data, principally dissolved nitrite plus nitrate (as nitrogen), and depth-to-water measurements for 67 wells in the Minidoka Irrigation District, south-central Idaho. Nitrogen concentrations ranged from 0.2 to 76 milligrams per liter; the median concentrations was 6.6 milligrams per liter. Nitrogen concentrations in 9 samples exceeded the U. S. Environmental Protection Agency public drinking-water limit of 10 milligrams per liter. (USGS)

  14. Hydrocarbon potential of Cambrian-Ordovician Knox Group in south-central Kentucky

    SciTech Connect

    Gooding, P.J.

    1987-09-01

    In the eastern US, the carbonate rocks of the Cambrian-Ordovician Knox Group were deposited on a broad, gently sloping continental shelf in shallow hypersaline waters. A major unconformity occurs at the top of the Knox Group. This regional unconformity developed when the Sauk Sea retreated at the close of the Early Ordovician. In south-central Kentucky, the paleotopographic surface is characterized by extensive paleokarst developed on the upper Knox surface. The study area is located on the crest of the Cincinnati arch, a major structural feature that separates the Appalachian basin to the east from the Illinois basin on the west. Oil and gas are being produced from Cambrian-Ordovician rocks throughout the US, and south-central Kentucky is no exception. In south-central Kentucky, the Knox is of considerable economic importance. Hydrocarbon entrapment occurs at or near the unconformity at the top of the Knox. Approximately 3500 oil and gas wells and mineral exploration holes have penetrated the upper Knox Group in south-central Kentucky. Over 32 million bbl of oil have been recovered from 11 relatively shallow stratigraphic zones in 120 oil pools. These stratigraphic zones are generally encountered at depths of less than 2000 ft. A substantial amount of oil has been recovered from pools that produce exclusively from the Knox. Brecciated and fractured zones at the top of the Knox have also served as the host rock for sulfide mineralization, and these deposits may contain significant amounts of lead, zinc, and barium resources for future exploitation.

  15. Holocene deposits of reservoir-quality sand along the Central South Carolina coastline

    SciTech Connect

    Sexton, W.J.; Hayes, M.O.

    1996-06-01

    The Holocene coastal sand deposits of the central South Carolina coastline were investigated to estimate volumes of reservoir-quality (RQ) sediments. These sand bodies, which vary considerably in size, thickness, shape, and continuity, were deposited in a variety of depositional settings including barrier islands, ebb-tidal deltas, exposed sand flats, tidal sand ridges, and tidal point bars. To identify the RQ sediment for each sand-body type, a conservative mud cutoff value of 15% was chosen. Average thickness values ranged from 6 m for barrier island deposits to 15 m for ebb-tidal deltas. Of the six most significant RQ sand depositional environments on the central portion of the South Carolina coast, ebb-tidal delta complexes accounted for 77% of all RQ sediments. This dominance of the ebb-tidal delta deposits is attributed to the relatively large tidal range in the area (up to 3 m) and to the presence of a number of large, incised alluvial valleys, which are host to estuarine complexes with large tidal prisms. If the Holocene sand deposits along the central 115 km of the South Carolina coast were preserved in the rock record, a total of 1.3 X 10{sup 6} ac-ft of RQ sands would be present, a significant amount considering the short time interval of approximately 5000 yr.

  16. Tribal engagement strategy of the South Central Climate Science Center, 2014

    USGS Publications Warehouse

    Andrews, William J.; Taylor, April; Winton, Kimberly T.

    2014-01-01

    The South Central Climate Science Center was established by the U.S. Department of the Interior in 2012 to increase understanding of climate change and coordinate an effective response to climate-change effects on Native American tribes and natural and cultural resources that the Department manages. The eight regional Climate Science Centers of the U.S. Department of the Interior work closely with natural-resource management agencies, university researchers, and others such as tribes and private landowners on climate-change issues. The relatively large number of Native Americans in the south central United States and their special knowledge of changing ecosystems make working with tribes and tribal members on climate-change issues particularly important in this part of the Nation. This circular describes priorities of the South Central Climate Science Center and provides information about resources available from Climate Science Centers and partner agencies regarding climate change. The circular also describes how this Climate Science Center, tribes and tribal members, and others can collaborate to minimize potential harmful effects of climate change on human society and our surrounding ecosystems.

  17. Methane and Carbon Cioxide Emissions from 40 Lakes Along a North-South Latitudinal Transect in Alaska

    NASA Astrophysics Data System (ADS)

    Walter Anthony, K. M.; Sepulveda-Jauregui, A.; Anthony, P.; Grosse, G.; Chanton, J.

    2014-12-01

    We assessed the relationship between CH4 and CO2 emission modes in 40 lakes along a latitudinal transect in Alaska to physicochemical limnology, geographic characteristics and permafrost soil types and carbon stocks surrounding lakes. We found that all lakes were net sources of atmospheric CH4 and CO2 but that the climate warming impact of lake CH4 emissions was two times higher than that of CO2. Ebullition and Diffusion were the dominant modes of CH4 and CO2 emissions respectively. Geographically, CH4 emissions from stratified, dystrophic interior Alaska thermokarst (thaw) lakes formed in icy, organic-rich yedoma permafrost soils were 6-fold higher than from non-yedoma lakes near Toolik Field Station and the rest of Alaska. Total CH4 emission was correlated with soil carbon stocks adjacent to lakes, concentrations of phosphate and total nitrogen in lake water, Secchi depth and lake area, with yedoma lakes having higher carbon stocks and nutrient concentrations, shallower Secchi depth, and smaller lake areas. Our findings suggest that permafrost type plays important roles in determining CH4 emissions from lakes by both supplying organic matter to methanogenesis directly from thawing permafrost and by enhancing nutrient availability to primary production, which can also fuel decomposition and methanogenesis.

  18. Deglaciation events in part of the Manchester South 7.5 degrees quadrangle south-central New Hampshire

    USGS Publications Warehouse

    Stone, Byron D.

    1971-01-01

    The study-area lies in south-central New Hampshire, and is bordered on the west by the Merrimack River, the principal north-south drainage route of central New Hampshire. The classical two tills of New England outcrop in the area. In a unique exposure of the sandy upper till, a loose ablation unit overlies a compact basal unit. Both upper till facies overlie a sheared section of dense, olive-gray lower till. Outwash sequences mapped in the study-area are progressively younger to the north, indicating backwastage of the Wisconsinan ice sheet. Primary structures in proglacial Lake Merrimack sediments include contorted bedding, buckled laminae, and folds. A large slumped section in lake sediments exhibits three distinct deformation zones, characterized by brittle, ductile, and unconsolidated deformation. Cross-cutting relationships establish four fold generations and a deformation sequence in the slumped section. Slip in each fold generation was along nearly parallel slip-lines, as deduced from analyses of fold rotation senses. The primary and slump deformation features contrast sharply with the intense style of deformation of lake beds below till at an apparent ice readvance cut. The deduced drag fold slip-line agrees with till fabric point maxima and dip-slip on one group of thrust faults. A southerly movement of readvancing ice is inferred. The study-area was deglaciated about 13,000 years ago, according to a proposed deglaciation model for New Hampshire. The model is based on Nye's theoretical glacier surface gradient, and evidence for active retreat of the Wisconsinan ice sheet.

  19. Distribution of planktonic cnidarians in response to South Atlantic Central Water intrusion in the South Brazilian Bight

    NASA Astrophysics Data System (ADS)

    Nogueira Júnior, Miodeli; Brandini, Frederico P.; Codina, Juan C. U.

    2014-10-01

    Five oceanographic cruises were made between November 2005 and June 2006, sampling a cross-shelf transect off the South Brazilian Bight (SBB; 26°46‧S) to follow the seasonal development of the South Atlantic Central Water (SACW) intrusion over the shelf and its influence on the assemblage of planktonic cnidarians. An onshore wind-driven bottom intrusion of the SACW was clearly perceptible, reaching the coast in January. From March onward, the SACW influence was gradually displaced seaward due to wind and tidal mixing. By late June the SACW influence was offshore and the inshore was dominated by low-salinity waters (<34.5). The abundance, distribution, and general taxonomic composition of both medusae and siphonophores were strongly influenced by the onshore intrusion of the SACW. An inshore-offshore gradient was clear. The Canonical Correspondence Analysis suggested that coastal species - dominated by Liriope tetraphylla, actinula larvae and Muggiaea kochi - were mostly related to food availability and a vertically mixed environment inshore, and their abundance and extent were reduced during intrusion periods. In contrast, species with offshore affinities tended to increase their abundance and distribution during intrusion periods, and were mostly related to the presence of thermal stratification and a deep chlorophyll maximum layer. Most of these offshore species, such as Aglaura hemistoma, Rhopalonema velatum and many calycophorans, are associated with the warm upper layer. However, high concentrations of large (>20 mm in diameter) Solmaris corona were observed exclusively in cold waters, suggesting this medusa is a SACW indicator.

  20. Compositional heterogeneity of central peaks within the South Pole-Aitken Basin

    NASA Astrophysics Data System (ADS)

    Moriarty, D. P.; Pieters, C. M.; Isaacson, P. J.

    2013-11-01

    high-spectral and -spatial resolution Moon Mineralogy Mapper data, we investigate compositional variations across the central peak structures of four impact craters within the South Pole-Aitken Basin (SPA). Two distinct causes of spectral diversity are observed. Spectral variations across the central peaks of Bhabha, Finsen, and Lyman are dominated by soil development, including the effects of space weathering and mixing with local materials. For these craters, the central peak structure is homogeneous in composition, although small compositional differences between the craters are observed. This group of craters is located within the estimated transient cavity of SPA, and their central uplifts exhibit similar mafic abundances. Therefore, it is plausible that they have all uplifted material associated with melts of the lower crust or upper mantle produced during the SPA impact. Compositional differences observed between the peaks of these craters reflect heterogeneities in the SPA subsurface, although the origin of this heterogeneity is uncertain. In contrast to these craters, Leeuwenhoek exhibits compositional heterogeneity across its central peak structure. The peak is areally dominated by feldspathic materials, interspersed with several smaller exposures exhibiting a mafic spectral signature. Leeuwenhoek is the largest crater included in the study and is located in a region of complex stratigraphy involving both crustal (feldspathic) and SPA (mafic melt and ejecta) materials. The compositional diversity observed in Leeuwenhoek's central peak indicates that kilometer-scale heterogeneities persist to depths of more than 10 km in this region.

  1. The tectonic development of south-central Asia and the paleogeographic setting of its hydrocarbon resources

    SciTech Connect

    Scotese, C.R. ); Tyrell, W.W. Jr. ); Maher, K.A. )

    1990-05-01

    The countries of south-central Asia (Afghanistan to Thailand) are made up of fragments of Gondwana that collided with the southern margin of Eurasia during the Mesozoic and Cenozoic. The Cimmerian terranes (Turkey, Iran, Afghanistan, Qiang Tang, and Burma-Malaya) rifted away from Gondwana beginning in the Late Carboniferous and were accreted to Asia during the Late Triassic-Jurassic. The Lhasa terrane, presumably also derived from Gondwana, was accreted during the Late Jurassic. By the Early Cretaceous, India-Madagascar had separated from Africa and from Australia-Antarctica. In the middle Cretaceous, India rapidly rifted away from Madagascar, and during the early Eocene collided with Asia giving rise to the Tibetam Plateau and the mountain belts from Afghanistan through Burma. The sedimentary basins and petroleum provinces adjacent to and south of these collision zones are best understood when viewed in the context of their tectonic history and paleogeographic setting. About 7 billion bbl of oil and 50 tcf of gas have been discovered in south-central Asia, mostly in Cenozoic deltaic sandstones or marine carbonate reservoirs in rift (Cambay), passive margin (Bombay shelf), and foreland basins (Assam, Indux, Potwar, Bengal) in India, Pakistan, and Bangladesh, and in a fore-arc setting in Burma. Source rocks are mostly Paleogene shale, but some Paleozoic and Mesozoic sources be present in Pakistan. New exploration is underway or will begin soon in India, Bangladesh, Nepal, and Burma.

  2. Multi-resolution Changes in the Spatial Extent of Perennial Arctic Alpine Snow and Ice Fields with Potential Archaeological Significance in the Central Brooks Range, Alaska

    NASA Astrophysics Data System (ADS)

    Tedesche, M. E.; Freeburg, A. K.; Rasic, J. T.; Ciancibelli, C.; Fassnacht, S. R.

    2015-12-01

    Perennial snow and ice fields could be an important archaeological and paleoecological resource for Gates of the Arctic National Park and Preserve in the central Brooks Range mountains of Arctic Alaska. These features may have cultural significance, as prehistoric artifacts may be frozen within the snow and ice. Globally significant discoveries have been made recently as ancient artifacts and animal dung have been found in melting alpine snow and ice patches in the Southern Yukon and Northwest Territories in Canada, the Wrangell mountains in Alaska, as well as in other areas. These sites are melting rapidly, which results in quick decay of biological materials. The summer of 2015 saw historic lows in year round snow cover extent for most of Alaska. Twenty mid to high elevation sites, including eighteen perennial snow and ice fields, and two glaciers, were surveyed in July 2015 to quantify their areal extent. This survey was accomplished by using both low flying aircraft (helicopter), as well as with on the ground in-situ (by foot) measurements. By helicopter, visual surveys were conducted within tens of meters of the surface. Sites visited by foot were surveyed for extent of snow and ice coverage, melt water hydrologic parameters and chemistry, and initial estimates of depths and delineations between snow, firn, and ice. Imagery from both historic aerial photography and from 5m resolution IKONOS satellite information were correlated with the field data. Initial results indicate good agreement in permanent snow and ice cover between field surveyed data and the 1985 to 2011 Landsat imagery-based Northwest Alaska snow persistence map created by Macander et al. (2015). The most deviation between the Macander et al. model and the field surveyed results typically occurred as an overestimate of perennial extent on the steepest aspects. These differences are either a function of image classification or due to accelerated ablation rates in perennial snow and ice coverage

  3. Geologic studies in Alaska by the U.S. Geological Survey, 1993

    USGS Publications Warehouse

    Till, Alison B.; Moore, Thomas E.

    1994-01-01

    This collection of 19 papers continues the annual series of U.S. Geological Survey reports on geologic investigations in Alaska. Contributions include 14 Articles and 5 shorter Geologic Notes that report results from all corners of the State.USGS activities in Alaska cover a broad spectrum of earth science topics, including the environment, hazards, resources, and geologic framework studies. Three articles focus on the environmental geochemistry of parts of south-central, west-central, and southwestern Alaska. An article on methane released from permafrost near Fairbanks and a note on paleowind direction indicators on the Arctic coastal plain contribute to ongoing climate and paleoclimate investigations. Landslide hazards in the Talkeetna Mountains and Wrangell-St. Elias National Park are discussed in two notes. Possible active fault traces near Alaska's main population center are described in an article on the Castle Mountain fault. An article on Aniakchak volcano presents evidence for a previously unrecognized catastrophic flooding event. Resources and resource assessment on gold, base metals, and coal are discussed in several articles and a note. Geologic framework studies cover tectonics, paleontology, stratigraphy, and metamorphic petrology. One contribution involves field methods; it evaluates the relative accuracy of global positioning systems and topographic map-based methods for deriving location data for field stations.Two bibliographies at the end of the volume list reports about Alaska in USGS publications released in 1993 and reports about Alaska by USGS authors in non-USGS publications in 1993.

  4. Methane and carbon dioxide emissions from 40 lakes along a north–south latitudinal transect in Alaska

    DOE PAGES

    Sepulveda-Jauregui, A.; Walter Anthony, K. M.; Martinez-Cruz, K.; ...

    2014-09-12

    Uncertainties in the magnitude and seasonality of various gas emission modes, particularly among different lake types, limit our ability to estimate methane (CH4) and carbon dioxide (CO2) emissions from northern lakes. Here we assessed the relationship between CH4 and CO2 emission modes in 40 lakes along a latitudinal transect in Alaska to physicochemical limnology and geographic characteristics, including permafrost soil type surrounding lakes. Emission modes included Direct Ebullition, Diffusion, Storage flux, and a newly identified Ice-Bubble Storage (IBS) flux. We found that all lakes were net sources of atmospheric CH4 and CO2, but the climate warming impact of lake CH4more » emissions was two times higher than that of CO2. Ebullition and Diffusion were the dominant modes of CH4 and CO2 emissions respectively. IBS, ~ 10% of total annual CH4 emissions, is the release to the atmosphere of seasonally ice-trapped bubbles when lake ice confining bubbles begins to melt in spring. IBS, which has not been explicitly accounted for in regional studies, increased the estimate of springtime emissions from our study lakes by 320%. Geographically, CH4 emissions from stratified, dystrophic interior Alaska thermokarst (thaw) lakes formed in icy, organic-rich yedoma permafrost soils were 6-fold higher than from non-yedoma lakes throughout the rest of Alaska. Total CH4 emission was correlated with concentrations of phosphate and total nitrogen in lake water, Secchi depth and lake area, with yedoma lakes having higher nutrient concentrations, shallower Secchi depth, and smaller lake areas. Our findings suggest that permafrost type plays important roles in determining CH4 emissions from lakes by both supplying organic matter to methanogenesis directly from thawing permafrost and by enhancing nutrient availability to primary production, which can also fuel decomposition and methanogenesis.« less

  5. Methane and carbon dioxide emissions from 40 lakes along a north-south latitudinal transect in Alaska

    NASA Astrophysics Data System (ADS)

    Sepulveda-Jauregui, A.; Anthony, K. M. Walter; Martinez-Cruz, K.; Greene, S.; Thalasso, F.

    2014-09-01

    Uncertainties in the magnitude and seasonality of various gas emission modes, particularly among different lake types, limit our ability to estimate methane (CH4) and carbon dioxide (CO2) emissions from northern lakes. Here we assessed the relationship between CH4 and CO2 emission modes in 40 lakes along a latitudinal transect in Alaska to physicochemical limnology and geographic characteristics, including permafrost soil type surrounding lakes. Emission modes included Direct Ebullition, Diffusion, Storage flux, and a newly identified Ice-Bubble Storage (IBS) flux. We found that all lakes were net sources of atmospheric CH4 and CO2, but the climate warming impact of lake CH4 emissions was two times higher than that of CO2. Ebullition and Diffusion were the dominant modes of CH4 and CO2 emissions respectively. IBS, ~ 10% of total annual CH4 emissions, is the release to the atmosphere of seasonally ice-trapped bubbles when lake ice confining bubbles begins to melt in spring. IBS, which has not been explicitly accounted for in regional studies, increased the estimate of springtime emissions from our study lakes by 320%. Geographically, CH4 emissions from stratified, dystrophic interior Alaska thermokarst (thaw) lakes formed in icy, organic-rich yedoma permafrost soils were 6-fold higher than from non-yedoma lakes throughout the rest of Alaska. Total CH4 emission was correlated with concentrations of phosphate and total nitrogen in lake water, Secchi depth and lake area, with yedoma lakes having higher nutrient concentrations, shallower Secchi depth, and smaller lake areas. Our findings suggest that permafrost type plays important roles in determining CH4 emissions from lakes by both supplying organic matter to methanogenesis directly from thawing permafrost and by enhancing nutrient availability to primary production, which can also fuel decomposition and methanogenesis.

  6. Variation of the upper mantle velocity structure along the central-south Andes

    NASA Astrophysics Data System (ADS)

    Liang, X.; Sandvol, E. A.; Shen, Y.; Gao, H.; Zhang, Z.

    2013-12-01

    Variations in the subduction angle of the Nazca plate beneath the South American plate has lead to different modes of deformation and volcanism along the Andean active margin. The volcanic gap between the central and southern Andean volcanic zones is correlated with the Pampean flat-slab subduction zone, where the subducting Nazca slab changes from a 30-degree dipping slab beneath the Puna plateau to a horizontal slab beneath the Sierras Pampeanas, and then to a 30-degree dipping slab beneath the south Andes from north to south. The Pampean flat-slab subduction correlates spatially with the track of the Juan Fernandez Ridge, and is associated with the inboard migration of crustal deformation. A major Pliocene delamination event beneath the southern Puna plateau has previously been inferred from geochemical, geological, and preliminary geophysical data. The mechanisms for the transition between dipping- and flat-subduction slab and the mountain building process of the central Andean plateau are key issues to understanding the Andean-type orogenic process. We use a new frequency-time normalization approach to extract very-broadband (up to 300 second) empirical Green's functions (EGFs) from continuous seismic records. The long-period EGFs provide the sensitivity needed to constrain the deep mantle structure. The broadband waveform data are from 393 portable stations of eight temporary networks: PUNA, SIEMBRA, CHARGE, RAMP, East Sierras Pampeanas, BANJO/SEDA, REFUCA, ANCORP, and 31 permanent stations accessed from both the IRIS DMC and GFZ GEOFON DMC. A finite difference wave propagation method is used to generate synthetic seismograms from 3-D velocity model. We use 3-D traveltime sensitivity kernels, and traveltime residuals measured by waveform cross-correlation to directly invert the upper mantle shear-wave velocity structure. The preliminary model shows strong along-strike velocity variations within in the mantle wedge and the subducting NAZCA slab. Low upper

  7. Variation of the upper mantle velocity structure along the central-south Andes

    NASA Astrophysics Data System (ADS)

    Liang, Xiaofeng; Sandvol, Eric; Shen, Yang; Gao, Haiying

    2014-05-01

    Variations in the subduction angle of the Nazca plate beneath the South American plate has lead to different modes of deformation and volcanism along the Andean active margin. The volcanic gap between the central and southern Andean volcanic zones is correlated with the Pampean flat-slab subduction zone, where the subducting Nazca slab changes from a 30-degree dipping slab beneath the Puna plateau to a horizontal slab beneath the Sierras Pampeanas, and then to a 30-degree dipping slab beneath the south Andes from north to south. The Pampean flat-slab subduction correlates spatially with the track of the Juan Fernandez Ridge, and is associated with the inboard migration of crustal deformation. A major Pliocene delamination event beneath the southern Puna plateau has previously been inferred from geochemical and geological and preliminary geophysical data. The mechanisms for the transition between dipping- and flat-subduction slab and the mountain building process of the central Andean plateau are key issues to understanding the Andean-type orogenic process. We use a new frequency-time normalization approach with non-linear stacking to extract very-broadband (up to 300 second) empirical Green's functions (EGFs) from continuous seismic records. The long-period EGFs provide the deeper depth-sensitivity needed to constrain the mantle structure. The broadband waveform data are from 393 portable stations of four temporary networks: PUNA, SIEMBRA, CHARGE, RAMP, East Sierras Pampeanas, BANJO/SEDA, REFUCA, ANCORP, and 31 permanent stations accessed from both the IRIS DMC and GFZ GEOFON DMC. A finite difference waveform propagation method is used to generate synthetic seismograms from 3-D velocity model. We use 3-D traveltime sensitivity kernels, and traveltime residuals measurement by waveform cross-correlation to directly invert the upper mantle shear-wave velocity structure. The preliminary model shows strong along-strike velocity variations within in the mantle wedge and

  8. Seismic hazard maps of Mexico, the Caribbean, and Central and South America

    USGS Publications Warehouse

    Tanner, J.G.; Shedlock, K.M.

    2004-01-01

    The growth of megacities in seismically active regions around the world often includes the construction of seismically unsafe buildings and infrastructures due to an insufficient knowledge of existing seismic hazard and/or economic constraints. Minimization of the loss of life, property damage, and social and economic disruption due to earthquakes depends on reliable estimates of seismic hazard. We have produced a suite of seismic hazard estimates for Mexico, the Caribbean, and Central and South America. One of the preliminary maps in this suite served as the basis for the Caribbean and Central and South America portion of the Global Seismic Hazard Map (GSHM) published in 1999, which depicted peak ground acceleration (pga) with a 10% chance of exceedance in 50 years for rock sites. Herein we present maps depicting pga and 0.2 and 1.0 s spectral accelerations (SA) with 50%, 10%, and 2% chances of exceedance in 50 years for rock sites. The seismicity catalog used in the generation of these maps adds 3 more years of data to those used to calculate the GSH Map. Different attenuation functions (consistent with those used to calculate the U.S. and Canadian maps) were used as well. These nine maps are designed to assist in global risk mitigation by providing a general seismic hazard framework and serving as a resource for any national or regional agency to help focus further detailed studies required for regional/local needs. The largest seismic hazard values in Mexico, the Caribbean, and Central and South America generally occur in areas that have been, or are likely to be, the sites of the largest plate boundary earthquakes. High hazard values occur in areas where shallow-to-intermediate seismicity occurs frequently. ?? 2004 Elsevier B.V. All rights reserved.

  9. Possible fault-bounded Early Mississippian Antler flysch trough in south-central Idaho

    SciTech Connect

    Wilson, E.; Link, P.K. . Dept. of Geology)

    1993-04-01

    The Mississippian Copper Basin Formation of south-central Idaho represents a submarine fan complex associated with the late Devonian to Early Mississippian Antler orogeny. Recent geologic investigations in the Pioneer Mountains demonstrate that the Copper Basin Formation contains over 5,500 meters of continuous section, as suggested years ago by R.A. Paull and students. The Early Mississippian paleogeography of east-central Idaho indicates a westward deepening asymmetric basin consistent with a foreland basin model. The authors estimated subsidence rate of 750 m/m.y. for the Copper Basin Formation is, however, higher than the most rapid foreland basin subsidence (300 m/m.y.), but is comparable with observed rates of 500 to 4,000 m/m.y. for pull-apart basins. Other evidence for a pull-apart basin is present in the Wildhorse Window, where up to 1,500m of Copper Basin Formation strata unconformably overlie tilted Ordovician, Silurian, and Devonian platform-facies sediments. A micrite-supported sedimentary breccia, possibly derived from erosion of the upthrown side of a syn-sedimentary fault, containing clasts of the lowest member of the Copper Basin Formation, stratigraphically overlies Devonian carbonates. These relations indicate a steep sided topographic high. It has long been recognized that neither coarse grained Antler flysch nor a demonstrable trace of an Antler thrust fault are present in Idaho south of the Snake River Plain. In Canada, the antler orogeny is associated with strike-slip tectonics and the formation of pull-apart basins. The authors work suggests that in south-central Idaho a strike-slip Antler orogen may be more reasonable than a thrust faulted highland and foreland basin.

  10. Age, Distribution, and Style of Deformation in Alaska North of 60°N: Implications for Assembly of Alaska

    NASA Astrophysics Data System (ADS)

    Moore, T. E.; Box, S. E.

    2015-12-01

    The structural architecture of Alaska is the product of a complex history of deformation along both the Cordilleran and Arctic margins of North America through interactions with ocean plates and with continental elements of Laurentia, Siberia, and Baltica. We use geological constraints to assign areal deformation to 14 time intervals and map their distributions in Alaska. Alaska can be divided into three domains with differing histories of deformation. The northern domain experienced the Early Cretaceous Brookian orogeny, an oceanic arc-continent collisional orogeny, followed by a mid-Cretaceous extensional overprint. Opening of the oceanic Canada Basin rifted the orogen from the Canadian Arctic margin, producing the bent trends of the orogen. The second domain constitutes the Phanerozoic Peninsular-Wrangellia-Alexander arc terrane and its paired Mesozoic accretionary prisms. Its structural history is unrelated to domains to the north until a shared history of Late Cretaceous deformation. The third domain, situated between the first two domains and roughly bounded by the Cenozoic dextral Denali and Tintina faults, includes the Yukon Composite terrane (Laurentian origin) and the large Farewell (Baltica origin) terrane. These terranes are not linked until Late Cretaceous sedimentary overlap, but we have not identified a shared deformation between these two terranes that might mark their juxtaposition by collisional processes. Similar early Late Cretaceous sedimentary linkages stitch the northern and central domains. Late Late Cretaceous folding and thrusting across much of Alaska south of the Brooks Range correlates temporally with the collision of the southern domain with the remainder of Alaska. Early Cenozoic shortening is mild across much of the state but is significant in the Brooks Range, and correlates in time with dextral faulting, ridge subduction, and rotation of western Alaska. Late Cenozoic shortening is significant in southern Alaska inboard of the

  11. Combined Ice and Water Balances of Gulkana and Wolverine Glaciers, Alaska, and South Cascade Glacier, Washington, 1965 and 1966 Hydrologic Years

    USGS Publications Warehouse

    Meier, Mark Frederick; Tangborn, Wendell V.; Mayo, Lawrence R.; Post, Austin

    1971-01-01

    Glaciers occur in northwestern North America between lat 37 deg and 69 deg N. in two major mountain systems. The Pacific Mountain System, near the west coast, receives large amounts of precipitation, has very mild temperatures, and contains perhaps 90 percent of the glacier ice. The Rocky Mountain or Eastern System, on the other hand, receives nearly an order of magnitude less precipitation, has temperatures that range from subpolar to subtropic, and contains glaciers that are much smaller in both size and total area. As a contribution to the International Hydrological Decade program on combined balances at selected glaciers, the U.S. Geological Survey is conducting studies of ice and water balance on four glaciers in the Pacific Mountain System: Wolverine and Gulkana Glaciers in Alaska, South Cascade Glacier in Washington, and Maclure Glacier in California. Similar data are being collected by other organizations at five glaciers in western Canada, including two in the Rocky Mountain System, and at one glacier in the Rocky Mountain System in northern Alaska. Gulkana, Wolverine, South Cascade, and Maclure Glaciers have dissimilar mass balances, and each is fairly representative of the glaciers for its particular region. Gulkana Glacier (lat 63 deg 15' N., Alaska Range, Alaska) normally has an equilibrium line at an altitude of 1,800 m (meters), an activity index of about 6 mm/m (millimeters per meter), a winter balance of about 1.0 m, and an annual exchange of about 2.2 m. (Balance values are given in terms of water-equivalent measure; the winter balance of 1 m, for example, indicates a volume of ice equal in mass to a volume of water 1 m in depth covering the area of the glacier.) The normal approximate parameters for the other glaciers studied are as follows: Wolverine Glacier (lat 60 deg 24' N., Kenai Mountains, Alaska) - equilibrium-line altitude 1,200 m, activity index 9 mm/m, winter balance 2.5 m, and annual exchange 5.5 m; South Cascade Glacier (lat 48 deg 22

  12. Physical characteristics of stream subbasins in the lower Minnesota River basin, south-central Minnesota

    USGS Publications Warehouse

    Sanocki, C.A.

    1997-01-01

    Data that describe the physical characteristics of stream subbasins upstream from selected sites on streams in the Lower Minnesota River Basin, located in south-central Minnesota are presented in this report. The physical characteristics are the drainage area of the subbasin, the percentage area of the subbasin covered only by lakes, the percentage area of the subbasin covered by both lakes and wetlands, the main-channel length, and the main-channel slope. Stream sites include outlets of subbasins of at least 5 square miles, outfalls of sewage treatment plants, and locations of U.S. Geological Survey low-flow, high-flow, and continuous-record gaging stations.

  13. Diarrhea and respiratory symptoms among travelers to Asia, Africa, and South and Central America from Scotland.

    PubMed

    Redman, Christopher Allan; Maclennan, Alice; Wilson, Eleanor; Walker, Eric

    2006-01-01

    Surveillance using admissions to hospital, while being useful, is a poor indicator of the real incidence of disease encountered by travelers. An alternative is self-reported illness among those who attended at a pretravel clinic prior to their travels. Estimates of incidence and risk factors were determined for attendees at a travel clinic in Scotland using a questionnaire. Analysis for risk factors was carried out for those travelers visiting countries in Africa, Asia, or South and Central America, who had traveled for 1 week or more and had returned between 1997 and 2001 (N= 4,856). Multivariate logistic regression was used to test the hypotheses that time abroad and age-group would be significant for both respiratory and diarrheal symptoms regardless of which of the three geographical areas are visited. From 2006 returned questionnaires (response rate = 41.3%), diarrhea and respiratory symptoms were reported by 44.2 and 16.8% of respondents, respectively; the incidence was significantly greater among travelers to Asia for both diarrheal (55.5%) and respiratory (23.7%) symptoms than among travelers to Africa (36.6 and 12.2%, respectively) or South and Central America (39.5 and 16.2%, respectively). For diarrhea, age was a highly significant risk factor for travelers to Asia, South and Central America, and Africa. Being a self-organized tourist/backpacker, traveling to Asia was associated with increased risk, while for Africa and South and Central America visiting family or friends was associated with a lower risk. For travelers to Asia, traveling to the Indian subcontinent was significantly associated with increased risk. The majority of travelers had an adverse event while traveling abroad, with diarrhea and respiratory conditions being especially common despite attending a travel clinic for advice prior to departure. However, the limitations of this surveillance-based strategy have highlighted the requirement for more research to understand more fully the

  14. Palynological and Iridium Anomalies at Cretaceous-Tertiary Boundary, South-Central Saskatchewan

    NASA Astrophysics Data System (ADS)

    Nichols, D. J.; Jarzen, D. M.; Orth, C. J.; Oliver, P. Q.

    1986-02-01

    The Cretaceous-Tertiary boundary in south-central Saskatchewan is marked by coincident anomalies in abundance of iridium and fern spores at the extinction level of a suite of Cretaceous pollen taxa. Evidence of disruption of the terrestrial flora includes the fern-spore abundance anomaly and local extinction of as much as 30 percent of angiosperm species. The reorganized earliest Tertiary flora is made up largely of surviving species that assumed new roles of dominance. Persistence of climatically sensitive taxa across the boundary indicates that if paleoclimate was altered by the terminal Cretaceous event, it returned quickly to the pre-event condition.

  15. Palynological and iridium anomalies at Cretaceous-Tertiary boundary, south-central Saskatchewan

    USGS Publications Warehouse

    Nichols, D.J.; Jarzen, D.M.; Orth, C.J.; Oliver, P.Q.

    1986-01-01

    The Cretaceous-Tertiary boundary in south-central Saskatchewan is marked by coincident anomalies in abundance of iridium and fern spores at the extinction level of a suite of Cretaceous pollen taxa. Evidence of disruption of the terrestrial flora includes the fern-spore abundance anomaly and local extinction of as much as 30 percent of angiosperm species. The reorganized earliest Tertiary flora is made up largely of surviving species that assumed new roles of dominance. Persistence of climatically sensitive taxa across the boundary indicates that if paleoclimate was altered by the terminal Cretaceous event, it returned quickly to the pre-event condition.

  16. Molecular characterization of adenovirus circulating in Central and South America during the 2006–2008 period

    PubMed Central

    García, Josefina; Sovero, Merly; Laguna‐Torres, Victor Alberto; Gomez, Jorge; Chicaiza, Wilson; Barrantes, Melvin; Sanchez, Felix; Jimenez, Mirna; Comach, Guillermo; De Rivera, Ivette L.; Agudo, Roberto; Arango, Ana E.; Barboza, Alma; Aguayo, Nicolas; Kochel, Tadeusz J.

    2009-01-01

    Background  Human Adenoviruses are recognized pathogens, causing a broad spectrum of diseases. Serotype identification is critical for epidemiological surveillance, detection of new strains and understanding of HAdvs pathogenesis. Little data is available about HAdvs subtypes in Latin America. Methods  In this study, we have molecularly characterized 213 adenoviruses collected from ILI presenting patients, during 2006‐08, in Central and South America. Results  Our results indicate that 161(76%) adenoviruses belong to subgroup C, 45 (21%) to subgroup B and 7 (3%) to subtype E4. PMID:19903214

  17. Reconnaissance geologic map of the Sangre de Cristo Wilderness Study Area, south-central Colorado

    USGS Publications Warehouse

    Johnson, Bruce R.; Lindsey, David A.; Bruce, R.M.; Soulliere, Sandra J.

    1987-01-01

    The Wilderness Act (Public Law 88-577, September 3, 1964) and related acts require the U.S. Geological Survey and the U.S. Bureau of Mines to survey certain areas on Federal lands to determine the mineral values, if any, that may be present. Results must be made available to the public and to be submitted to the President and Congress. This report presents the results of geologic studies in the Sangre de Cristo Wilderness Study Area in the Rio Grande and San Isabel National Forests, south-central Colorado. The area was designated as a wilderness study area under Public Lay 96-560 in 1980. 

  18. Organic pollutant burden of the giant mussels Choromytilus chorus from the south-central Chilean coast.

    PubMed

    Toro, Beatriz; Palma-Fleming, Hernán; Navarro, Jorge M

    2004-04-01

    A comparative quantitative analysis was made on the contents of organochlorines (OCh) and polycyclic aromatic hydrocarbons (PAH) in tissues of the giant mussel Choromytilus chorus from three bays in south-central Chile exposed to various degrees of pollutant input. Mussels from the three bays contained levels of OCh near the detection limits of method, with a tendency to be slightly higher in the polluted bay (San Vicente) than in the other bays (Corral and Yaldad). PAH levels and types in Corral and Yaldad were well below of carcinogenicity permitted in mussels for human consumption.

  19. Escherichia Coli monitoring in the Spring Mill Lake watershed in south-central Indiana

    USGS Publications Warehouse

    Hasenmueller, N.R.; Comer, J.B.; Zamani, D.D.; ,

    2003-01-01

    The escherichila (E) coli monitoring in the Spring Mill lake watershed in South-Central Indiana was presented. Water flowing from the springs in the park were analyzed to determine potential nonpoint-source contaminants entering Spring Mill Lake. E. Coli concentrations from the monitoring sites within the Spring Mill Lake watersheds varied greatly from concentrations below the detection limit, <1 most probable number (MPN) of organisms per 100 milliliters (mL) of water, to 980,000 MPN/100 mL. E. coli appears to be a potential health risk at several of the springs within the park, particularly at the Rubble site.

  20. Trace element content of leaves of desert shrubs in south-central Washington

    SciTech Connect

    Rickard, W.H.; Garland, T.R.

    1983-01-01

    Analyses of leaves of desert shrubs showed strong differences in macroelements according to species and location on the Arid Lands Ecology (ALE) site in south-central Washington. Halophytes were characterized by high levels of K, Cl, Br, Mn, and Na, and glycophytes by high levels of Ca and Mg. However, trace element content was not significantly different. Big sagebrush (Artemisia tridentata) leaves from Wyoming and the ALE site were not greatly different in trace element content. Natural leaf fall collections can be used to monitor changing levels of trace element content induced by coal combustion steam-electric plants.

  1. Impacts of land use and climate change on carbon dynamics in south-central Senegal

    USGS Publications Warehouse

    Liu, Shu-Guang; Kaire, M.; Wood, Eric C.; Diallo, O.; Tieszen, Larry L.

    2004-01-01

    Total carbon stock in vegetation and soils was reduced 37% in south-central Senegal from 1900 to 2000. The decreasing trend will continue during the 21st century unless forest clearing is stopped, selective logging dramatically reduced, and climate change, if any, relatively small. Developing a sustainable fuelwood and charcoal production system could be the most feasible and significant carbon sequestration project in the region. If future climate changes dramatically as some models have predicted, cropland productivity will drop more than 65% around 2100, posing a serious threat to food security and the efficiency of carbon sequestration projects.

  2. CYP2A6 and CYP2B6 genetic variation and its association with nicotine metabolism in South Western Alaska Native people

    PubMed Central

    Binnington, Matthew J.; Zhu, Andy Z.X.; Renner, Caroline C.; Lanier, Anne P.; Hatsukami, Dorothy K.; Benowitz, Neal L; Tyndale, Rachel F.

    2012-01-01

    Objectives Alaska Native people (AN) have a high prevalence of tobacco use and associated morbidity and mortality when compared to the general U.S. population. Variation in the CYP2A6 and CYP2B6 genes, encoding enzymes responsible for nicotine metabolic inactivation and procarcinogen activation, has not been characterized in AN and may contribute to the increased risk. Methods AN people (n = 400) residing in the Bristol Bay region of South Western Alaska were recruited for a cross-sectional study on tobacco use. They were genotyped for CYP2A6*1X2A, *1X2B, *1B, *2, *4, *7, *8, *9, *10, *12, *17, *35 and CYP2B6*4, *6, *9 and provided plasma and urine samples for measurement of nicotine and metabolites. Results CYP2A6 and CYP2B6 variant frequencies among the AN Yupik people (n=361) were significantly different from other ethnicities. Nicotine metabolism (as measured by the plasma and urinary ratio of metabolites trans-3’hydroxycotinine to cotinine [(3HC/COT)] was significantly associated with CYP2A6 (P< 0.001) but not CYP2B6 genotype (P = 0.95) when controlling for known covariates. Of note, plasma 3HC/COT ratios were high in the entire Yupik people, and among the Yupik CYP2A6 wild-type participants they were substantially higher than previously characterized racial/ethnic groups (P < 0.001 vs. Caucasians and African Americans). Conclusions Yupik AN people have a unique CYP2A6 genetic profile which associated strongly with in vivo nicotine metabolism. More rapid CYP2A6-mediated nicotine and nitrosamine metabolism in the Yupik people may modulate tobacco-related disease risk. PMID:22569203

  3. The nature of the crust in the Yukon-Koyukuk province as inferred from the chemical and isotopic composition of five Late Cretaceous to Early Tertiary volcanic fields in western Alaska

    USGS Publications Warehouse

    Moll-Stalcup, E.; Arth, Joseph G.

    1989-01-01

    Late Cretaceous and early Tertiary volcanic and plutonic rocks in western Alaska comprise a vast magmatic province extending from the Alaska Range north to the Arctic Circle, south to Bristol Bay, and west to the Bering Sea Shelf. The chemical and isotopic composition of five of these Late Cretaceous to early Tertiary volcanic fields in the north central part of this province were studied to determine if Paleozoic or older continental crust underlies the Yukon-Koyukuk province. -from Authors

  4. Crustal Rheology and Rifted Margin Architecture: Comparing Iberia-Newfoundland, Central South Atlantic, and South China Sea

    NASA Astrophysics Data System (ADS)

    Brune, Sascha

    2015-04-01

    Crustal rheology controls the style of rifting and ultimately the architecture of rifted margins: Hot, weak, or thick continental crust is dominated by ductile deformation and extends symmetrically into a wide rift system. Extension in cold, strong, or thin crust is accommodated by brittle faults and ductile shear zones that facilitate narrow rifts with asymmetric fault geometries. This recipe provides the standard framework to understand 2D rift geometry, however, a variety of processes exert significant control on subsequent rift evolution and ultimately on the architecture of rifted margins: inherited structures, melting and volcanism, 3D effects, extension rate, and weakening mechanisms. Numerical forward modelling studies have the opportunity to evaluate the influence of these processes on rift evolution in order to understand the complex interaction between rheology and tectonic history of specific margins. Here I compare the formation of three different magma-poor margin pairs, Iberia-Newfoundland, the Central South Atlantic Rift Segment, and the South China Sea margins within a numerical forward modelling framework. I apply a 2D version of the finite element code SLIM3D, which includes nonlinear temperature- and stress-dependent elasto-visco-plastic rheology and is able to reproduces a wide range of rift-related deformation processes such as flexure, lower crustal flow, and faulting. The Iberia-Newfoundland rifted margins are marked by moderate crustal asymmetry, with ~70 km of hyper-extended crust (less than 10 km thick) on the Iberian side and a very narrow margin on the Newfoundland counterpart. Similar to the Iberia-Newfoundland conjugates, the Central South Atlantic margins are predominantly asymmetric, however involve a much stronger degree of asymmetry with more than 200 km of hyper-extended crust offshore Angola, but only few tens of km at the Brazilian side. Kinematic and numerical modelling suggests that the asymmetry is caused by lateral

  5. Structural and kinematic evolution of the Yukon-Tanana upland tectonites, east-central Alaska: A record of late Paleozoic to Mesozoic crustal assembly

    USGS Publications Warehouse

    Hansen, V.L.; Dusel-Bacon, C.

    1998-01-01

    The Yukon-Tanana terrane, the largest tectonostratigraphic terrane in the northern North American Cordillera, is polygenetic and not a single terrane. Lineated and foliated (L-S) tectonites, which characterize the Yukon-Tanana terrane, record multiple deformations and formed at different times. We document the polyphase history recorded by L-S tectonites within the Yukon-Tanana upland, east-central Alaska. These upland tectonites compose a heterogeneous assemblage of deformed igneous and metamorphic rocks that form the Alaskan part of what has been called the Yukon-Tanana composite terrane. We build on previous kinematic data and establish the three-dimensional architecture of the upland tectonites through kinematic and structural analysis of more than 250 oriented samples, including quartz c-axis fabric analysis of 39 samples. Through this study we distinguish allochthonous tectonites from parautochthonous tectonites within the Yukon-Tanana upland. The upland tectonites define a regionally coherent stacking order: from bottom to top, they are lower plate North American parautochthonous attenuated continental margin; continentally derived marginal-basin strata; and upper plate ocean-basin and island-arc rocks, including some continental basement rocks. We delineate three major deformation events in time, space, and structural level across the upland from the United States-Canada border to Fairbanks, Alaska: (1) pre-Early Jurassic (>212 Ma) northeast-directed, apparent margin-normal contraction that affected oceanic rocks; (2) late Early to early Middle Jurassic (>188-185 Ma) northwest-directed, apparent margin-parallel contraction and imbrication that resulted in juxtaposition of the allochthonous tectonites with parautochthonous continental rocks; and (3) Early Cretaceous (135-110 Ma) southeast-directed crustal extension that resulted in exposure of the structurally deepest, parautochthonous continental rocks. The oldest event represents deformation within a west

  6. A conceptual model for the link between Central American biomass burning aerosols and severe weather over the south central United States

    NASA Astrophysics Data System (ADS)

    Wang, Jun; van den Heever, Susan C.; Reid, Jeffrey S.

    2009-01-01

    Each spring, smoke particles from fires over the Yucatan Peninsula and south Mexico cross over the Gulf of Mexico into the United States (US) under the control of moist oceanic air flow from the southwestern branch of the subtropical (Bermuda) high. Smoke can be transported deep into the south central US, where dry lines and warm conveyor belts are frequently formed and cause deep convection and severe weather. Lyons et al (1998 Science 282 77-80) and Murray et al (2000 Geophys. Res. Lett. 27 2249-52) noticed a ~50% increase of lightning along the smoke transport path over the south central US during the May 1998 Central American smoke episode. Here we present a conceptual model of coherent microphysical and meteorological mechanisms through which smoke may impact convective clouds and subsequently result in more severe weather over the south central US. The conceptual model depicts a chain of processes in which smoke particles are first activated as cloud condensation nuclei when they are entrained into the warm conveyor belt, a convective zone formed over the south central US as a result of the encounter between the mid-latitude trough and the subtropical Bermuda high. As the convection continues with deepening of the mid-latitude trough, the greater concentration of water cloud condensation nuclei delays the warm rain processes, enhances the development of ice clouds, and invigorates the updrafts, all of which contribute to the formation of severe weather such as hail and lightning. The conceptual model is based on the reasoning of physical mechanisms revealed in previous studies (over the tropical biomass region), and is supported here through the analysis of satellite data, ground observations, aerosol transport model results, and idealized cloud resolving simulations of a day in May 2003 when record tornado events occurred over the south central US. Further assessment of this conceptual model is discussed for future investigations.

  7. Ages for hominin occupation in Lushi Basin, middle of South Luo River, central China.

    PubMed

    Lu, Huayu; Sun, Xuefeng; Wang, Shejiang; Cosgrove, Richard; Zhang, Hongyan; Yi, Shuangwen; Ma, Xiaolin; Wei, Ming; Yang, Zhenyu

    2011-05-01

    A newly discovered Paleolithic site in loess deposits in the Lushi Basin, South Luo River, central China, is dated using pedostratigraphic analysis, optically stimulated luminescence (OSL) and magnetostratigraphic analysis. This region is regarded as an important place for hominin occupation and settlement during the early to middle Pleistocene. Results indicate that the archaeological site dates from 600ka to 620ka, reinforcing the view that Homo erectus had occupied a large area of eastern Asia by 620ka. The lithic assemblages of Lushi Basin is a flake and core technology, typical for this time period in north-central China. It may be compared with that at the Zhoukoudian locality 1 in north China and some sites in the Luonan Basin, and provides important data for understanding the behavior and stone tool technology of early Chinese hominins.

  8. Central and South West Services (CSWS) transmission system studies: (Rio Grande Valley FACTS studies). Final report

    SciTech Connect

    Arabi, S.; Hamadanizadeh, H.

    1998-12-01

    Stability limitations impose constraints on power imports into the Rio Grande Valley, the southern region of Central Power and Light`s (CPL) system. CPL`s parent company, Central and South West Services, sought to identify viable plans for eliminating these constraints to enable power transfers via two 345-kV transmission lines. This project conducted assessment studies of the CPL system, using applications from EPRI`s Power System Analysis Package, and identified two scenarios as the most likely remedial measures required. These consisted of the addition of generating units and the use of series compensation of the two transmission lines, in conjunction with shunt compensation. While Flexible AC Transmission System (FACTS) devices were not indicated in this study phase, the researchers indicated a Thyristor Controlled Series Compensation device could be considered to address a potential subsynchronous resonance issue.

  9. Seismic Stratigraphy of the Central South China Sea Basin and Implications for Neotectonics

    NASA Astrophysics Data System (ADS)

    Li, C. F.; Ding, W.; Franke, D.; Yao, Y.; Pang, X.; Shi, H.; Li, J.; Cao, Y.

    2014-12-01

    International Ocean Discovery Program (IODP) Expedition 349 drilled five sites in the central South China Sea Basin. Three sites (U1431 in the East Subbasin, and U1433 and U1434 in the Southwest Subbasin) reached basalt interpreted to be igneous basement of the oceanic crust. Site U1435 on the northern continent-ocean boundary recovered pre-Oligocene sedimentary rocks deposited prior to the opening of the South China Sea. Furthermore, a full suite of geophysical logging was also carried out at Sites U1431 and U1433. These coring and logging data and physical property measurements are integrated with, and correlated to, regional reflection seismic data to map regional sequence stratigraphic boundaries and seismic facies of the central basin and the continent-ocean transition zone. With our carefully selected seismic profiles, stratigraphic correlation is possible even between the continent-ocean transition zone and the central basin, circumventing preexisting basement highs near the continent-ocean boundary that often prevent direct correlation. We interpret four sequence boundaries, which are Oligocene/Miocene, middle Miocene/late Miocene, Miocene/Pliocene, and Pliocene/Pleistocene boundaries. Seismic facies between sequence boundaries are often characteristic and distinctive, allowing relatively straightforward regional correlation. For example, massive Miocene carbonate deposits, if well consolidated, are readily distinguishable by strong seismic reflectivities, caused by their relatively higher density and velocity in contrast to those of interbedded turbidite clastic sediments. However, we found abrupt seismic facies changes both temporally and spatially. In particular, the fossil spreading ridge and the Zhongnan ridge between the East and Southwest Subbasins acted as major sedimentary barriers, across which seismic facies changes sharply and cannot be easily correlated. The well-constrained seismic sequence boundaries also allow us to estimate the timing of

  10. Coordination and establishment of centralized facilities and services for the University of Alaska ERTS survey of the Alaskan environment

    NASA Technical Reports Server (NTRS)

    Belon, A. E. (Principal Investigator); Miller, J. M.

    1973-01-01

    The author has identified the following significant results. Scene 1072-21173 of the Anaktuvuk Pass region of the Brooks Range, Alaska, was studied from the point of view of a resource survey for purposes of land use planning as part of the effort to develop ERTS data processing and interpretation techniques. Other data sources and surface observations were utilized to produce a resource survey of a remote and undeveloped region of Alaska. Three vegetative types are apparent: moist tundra, low brush, and high brush. Watersheds are easily defined on the multispectral imagery. Features related indirectly to economic minerals are discernible from ERTS-1 imagery supported by ground truth data. These include mountains, outwash plains and alluvial deposits, drainage patterns, lineaments and probable bedding planes. This region falls within present land class categories which are not inconsistent with the imperatives of the resources. These land class categories include native village withdrawals, regional deficiency area, national interest study area for possible inclusion in a national system, public interest areas, utility corridor, and state land selection.

  11. Methane and carbon dioxide emissions from 40 lakes along a north-south latitudinal transect in Alaska

    NASA Astrophysics Data System (ADS)

    Sepulveda-Jauregui, A.; Anthony, K. M. Walter; Martinez-Cruz, K.; Greene, S.; Thalasso, F.

    2015-06-01

    Uncertainties in the magnitude and seasonality of various gas emission modes, particularly among different lake types, limit our ability to estimate methane (CH4) and carbon dioxide (CO2) emissions from northern lakes. Here we assessed the relationship between CH4 and CO2 emission modes in 40 lakes along a latitudinal transect in Alaska to lakes' physicochemical properties and geographic characteristics, including permafrost soil type surrounding lakes. Emission modes included direct ebullition, diffusion, storage flux, and a newly identified ice-bubble storage (IBS) flux. We found that all lakes were net sources of atmospheric CH4 and CO2, but the climate warming impact of lake CH4 emissions was 2 times higher than that of CO2. Ebullition and diffusion were the dominant modes of CH4 and CO2 emissions, respectively. IBS, ~10% of total annual CH4 emissions, is the release to the atmosphere of seasonally ice-trapped bubbles when lake ice confining bubbles begins to melt in spring. IBS, which has not been explicitly accounted for in regional studies, increased the estimate of springtime emissions from our study lakes by 320%. Geographically, CH4 emissions from stratified, mixotrophic interior Alaska thermokarst (thaw) lakes formed in icy, organic-rich yedoma permafrost soils were 6-fold higher than from non-yedoma lakes throughout the rest of Alaska. The relationship between CO2 emissions and geographic parameters was weak, suggesting high variability among sources and sinks that regulate CO2 emissions (e.g., catchment waters, pH equilibrium). Total CH4 emission was correlated with concentrations of soluble reactive phosphorus and total nitrogen in lake water, Secchi depth, and lake area, with yedoma lakes having higher nutrient concentrations, shallower Secchi depth, and smaller lake areas. Our findings suggest that permafrost type plays important roles in determining CH4 emissions from lakes by both supplying organic matter to methanogenesis directly from thawing

  12. Methane and carbon dioxide emissions from 40 lakes along a north–south latitudinal transect in Alaska

    DOE PAGES

    Sepulveda-Jauregui, A.; Walter Anthony, K. M.; Martinez-Cruz, K.; ...

    2015-06-02

    Uncertainties in the magnitude and seasonality of various gas emission modes, particularly among different lake types, limit our ability to estimate methane (CH4) and carbon dioxide (CO2) emissions from northern lakes. Here we assessed the relationship between CH4 and CO2 emission modes in 40 lakes along a latitudinal transect in Alaska to lakes' physicochemical properties and geographic characteristics, including permafrost soil type surrounding lakes. Emission modes included direct ebullition, diffusion, storage flux, and a newly identified ice-bubble storage (IBS) flux. We found that all lakes were net sources of atmospheric CH4 and CO2, but the climate warming impact of lakemore » CH4 emissions was 2 times higher than that of CO2. Ebullition and diffusion were the dominant modes of CH4 and CO2 emissions, respectively. IBS, ~10% of total annual CH4 emissions, is the release to the atmosphere of seasonally ice-trapped bubbles when lake ice confining bubbles begins to melt in spring. IBS, which has not been explicitly accounted for in regional studies, increased the estimate of springtime emissions from our study lakes by 320%. Geographically, CH4 emissions from stratified, mixotrophic interior Alaska thermokarst (thaw) lakes formed in icy, organic-rich yedoma permafrost soils were 6-fold higher than from non-yedoma lakes throughout the rest of Alaska. The relationship between CO2 emissions and geographic parameters was weak, suggesting high variability among sources and sinks that regulate CO2 emissions (e.g., catchment waters, pH equilibrium). Total CH4 emission was correlated with concentrations of soluble reactive phosphorus and total nitrogen in lake water, Secchi depth, and lake area, with yedoma lakes having higher nutrient concentrations, shallower Secchi depth, and smaller lake areas. Our findings suggest that permafrost type plays important roles in determining CH4 emissions from lakes by both supplying organic matter to methanogenesis directly from

  13. Geologic map of the Alamosa 30’ × 60’ quadrangle, south-central Colorado

    USGS Publications Warehouse

    Thompson, Ren A.; Shroba, Ralph R.; Michael N. Machette,; Fridrich, Christopher J.; Brandt, Theodore R.; Cosca, Michael A.

    2015-10-15

    The Alamosa 30'× 60' quadrangle is located in the central San Luis Basin of southern Colorado and is bisected by the Rio Grande. The Rio Grande has headwaters in the San Juan Mountains of Colorado and ultimately discharges into the Gulf of Mexico 3,000 kilometers (km) downstream. Alluvial floodplains and associated deposits of the Rio Grande and east-draining tributaries, La Jara Creek and Conejos River, occupy the north-central and northwestern part of the map area. Alluvial deposits of west-draining Rio Grande tributaries, Culebra and Costilla Creeks, bound the Costilla Plain in the south-central part of the map area. The San Luis Hills, a northeast-trending series of flat-topped mesas and hills, dominate the landscape in the central and southwestern part of the map and preserve fault-bound Neogene basin surfaces and deposits. The Precambrian-cored Sangre de Cristo Mountains rise to an elevation of nearly 4,300 meters (m), almost 2,000 m above the valley floor, in the eastern part of the map area. In total, the map area contains deposits that record surficial, tectonic, sedimentary, volcanic, magmatic, and metamorphic processes over the past 1.7 billion years.

  14. Tectonics and depositional environments in early Pennsylvanian of south-central New Mexico

    SciTech Connect

    Kalesky, J. )

    1987-02-01

    The Pennsylvanian Magdalena Group unconformably overlies Precambrian to Mississippian strata throughout south-central New Mexico. Regional southward tilting, warping, and erosion resulted in progressively older pre-Pennsylvanian subcrop relations from south to north. Normal marine shelf sedimentation was represented by upward shoaling cycles containing mixed siliciclastics and carbonates. Channels cut into Ordovician strata in the southern Caballo Mountain area suggest that this area was a relatively deep valley or trough during Late Mississippian-Early Pennsylvanian erosion. Marine transgression from the south backfilled the preexisting stream valleys with sequences of packstone, wackestone, shale, and coarse quartzarenite. Topographically higher areas were blanketed with thin beds of laminated bioclastic packstone, grainstone, lime mudstone, and shale. Semirestricted tidal to nearshore environments are reflected in local sections by finely laminated hematitic dolomites, oncolitic wackestones, limestone conglomerates containing reworked Mississippian chert, and terrigenous shales supporting petrified wood float. Depositional onlap farther north resulted in a thinner and younger sequence. The cyclic nature of these deposits reflects a proximity to the shoreline and suggests an abruptly shifting base level, possibly controlled by Early Pennsylvanian glacial eustasy. The time-stratigraphic position of the valley-fill depositional unit may be broadly correlated to other Late Mississippian-Early Pennsylvanian valley-fill sequences recognized in the Delaware basin and Grand Canyon.

  15. The 'loessic palaeolithic' in South Tadjikistan, central Asia: Its industries, chronology and correlation

    NASA Astrophysics Data System (ADS)

    Ranov, Vadim

    This paper starts with an introductory account of the Loessic Palaeolithic, a term used by the author from 1987 to describe those Palaeolithic sites which are associated with very thick loess-palaeosol successions. Following a discussion on Movius' hypothesis on the Lower Palaeolithic industry of Eurasia, a brief description of four major Palaeolithic sites in South Tadjikistan is given.'The main sites are Kuldara (0.8 Ma), Karatau 1(0.2 Ma), Lakhuti 1(0.13 Ma) and Obi-Mazar (0.09 Ma). They represent different periods of slowly evolved pebble culture without new influence from other regions. The main features of the Stone Age industry called 'Karatau culture' are as follows: the clear pebble technique without prepared core, bifacial and Levallois techniques; dispersion of the pebble-tools-choppers, stone slices, wedges, unifaces; and flakes which are not stable for this form and dimensions. The blades are practically absent. No series of the tools is observed and they are the side scrapers, 'scrapers on occasion', borers, points, carinate tools. The Karatau culture is similar to the lower Palaeolithic industries of China. The Karatau culture in South Tadjikistan has better geological context than other pebble industries of Central and South Asia.

  16. Holocene coseismic and aseismic uplift of Isla Mocha, south-central Chile

    USGS Publications Warehouse

    Nelson, A.R.; Manley, W.F.

    1992-01-01

    During the past 6000 years Isla Mocha, a 12 km-long island 30 km off the coast of south-central Chile, experienced a 38 m fall of relative sea level caused primarily by rapid tectonic uplift of the island. As many as 18 raised shorelines (strandlines) record this uplift. Historic accounts of uplift during the great earthquakes (M > 8) of 1835 and 1960 suggest some of the more prominent prehistoric strandlines also emerged during great earthquakes on the interface between the Nazca and South America plates. But the close elevational spacing of strandlines, subdued morphology of strandline beaches, scarcity of exposed bedrock wave-cut platforms, and the extremely high rates of aseismic uplift (ca. 70 mm/yr) of the island since the last great earthquake suggest that many strandlines were raised by aseismic rather than coseismic uplift. Strandline heights and 14 new radiocarbon ages on marine shells show that the present-day uplift rate is more than three times the net rate (ca. 20 mm/yr) of the past 1000 years. The recent high rate probably reflects increased aseismic slip on an inferred thrust fault in the overriding South America plate. Isla Mocha overlies an area of high stress concentration between two major segments of the Chilean subduction zone. The inferred high rate of slip on the thrust fault may be a response to stress changes on the plate interface near the boundary between the segments. ?? 1992.

  17. A preliminary evaluation of regional ground-water flow in south-central Washington

    USGS Publications Warehouse

    La Sala, A. M.; Doty, G.C.; Pearson, F.J.

    1973-01-01

    The characteristics of regional ground-water flow were investigated in a 4,500-square-mile region of south-central Washington, centered on the U.S. Atomic Energy Commission Hanford Reservation. The investigation is part of the Commission's feasibility study on storing high-level radioactive waste in chambers mined in basaltic rocks at a. depth of about 3,000 feet or more below the surface. Ground-water flow., on a regional scale, occurs principally in the basalt and-in interbedded sediments of the Columbia River Group, and is controlled by topography, the structure of the basalt, and the large streams--the Columbia, Snake, and Yakima Rivers. The ground water beneath the main part of the Hanford Reservation, south and west of the Columbia River, inures southeastward from recharge areas in the uplands, including Cold Creek and Dry Creek valleys, and ultimately discharges to the Columbia River south of the reservation: East and southeast of the Columbia River, ground water flows generally southwestward and discharges to the River. The Yakima River valley contains a distinct flow system in which movement is toward the Yakima River from the topographic divides. A large southward-flowing ground-water system beneath the southern flank of the Horse Heaven Hills discharges to the Columbia River in the westward-trending reach downstream from Wallula Gap.

  18. Lower Paleozoic deep-water facies of the Medfra area, central Alaska: A section in Geologic studies in Alaska by the U.S. Geological Survey, 1997

    USGS Publications Warehouse

    Dumoulin, Julie A.; Bradley, Dwight C.; Harris, Anita G.; Repetski, John E.

    1999-01-01

    Deep-water facies, chiefly hemipelagic deposits and turbidites, of Cambrian through Devonian age are widely exposed in the Medfra and Mt. McKinley quadrangles. These strata include the upper part of the Telsitna Formation (Middle-Upper Ordovician) and the Paradise Fork Formation (Lower Silurian-Lower Devonian) in the Nixon Fork terrane, the East Fork Hills Formation (Upper Cambrian-Lower Devonian) in the East Fork subterrane of the Minchumina terrane, and the chert and argillite unit (Ordovician) and the argillite and quartzite unit (Silurian- Devonian? and possibly older) in the Telida subterrane of the Minchumina terrane.In the western part of the study area (Medfra quadrangle), both hemipelagic deposits and turbidites are largely calcareous and were derived from the Nixon Fork carbonate platform. East- ern exposures (Mt. McKinley quadrangle; eastern part of the Telida subterrane) contain much less carbonate; hemipelagic strata are mostly chert, and turbidites contain abundant rounded quartz and lesser plagioclase and potassium feldspar. Deep-water facies in the Medfra quadrangle correlate well with rocks of the Dillinger terrane exposed to the south (McGrath quadrangle), but coeval strata in the Mt. McKinley quadrangle are compositionally similar to rocks to the northeast (Livengood quadrangle). Petrographic data thus suggest that the Telida subterranes presently defined is an artificial construct made up of two distinct sequences of disparate provenance.Restoration of 90 and 150 km of dextral strike-slip on the Iditarod and Farewell faults, respectively, aligns the deep-water strata of the Minchumina and Dillinger terranes in a position east of the Nixon Fork carbonate platform. This restoration supports the interpretation that lower Paleozoic rocks in the Nixon Fork and Dillinger terranes, and in the western part of the Minchumina terrane (East Fork subterrane and western part of the Telida subterrane), formed along a single continental margin. Rocks in the

  19. Geologic studies in Alaska by the U.S. Geological Survey, 1992

    USGS Publications Warehouse

    Dusel-Bacon, Cynthia; Till, Alison B.

    1993-01-01

    This collection of 19 papers continues the annual series of U.S. Geological Survey reports on the geology of Alaska. The contributions, which include full-length Articles and shorter Geologic Notes, cover a broad range of topics including dune formation, stratigraphy, paleontology, isotopic dating, mineral resources, and tectonics. Articles, grouped under four regional headings, span nearly the entire State from the North Slope to southwestern, south-central, and southeastern Alaska (fig. 1).In the section on northern Alaska, Galloway and Carter use new data on dune morphology and radiocarbon ages from the western Arctic Coastal Plain to develop a late Holocene chronology of multiple episodes of dune stabilization and reactivation for the region. Their study has important implications for climatic changes in northern Alaska during the past 4,000 years. In two papers, Dumoulin and her coauthors describe lithofacies and conodont faunas of Carboniferous strata in the western Brooks Range, discuss depositional environments, and propose possible correlations and source areas for some of the strata. Schenk and Bird propose a preliminary division of the Lower Cretaceous stratigraphic section in the central part of the North Slope into depositional sequences. Aleinikoff and others present new U-Pb data for zircons from metaigneous rocks from the central Brooks Range. Karl and Mull, reacting to a proposal regarding terrane nomenclature for northern Alaska that was published in last year's Alaskan Studies Bulletin, provide a historical perspective of the evolution of terminology for tectonic units in the Brooks Range and present their own recommendations.

  20. Helicopter electromagnetic and magnetic geophysical survey data, Hunton anticline, south-central Oklahoma

    USGS Publications Warehouse

    Smith, Bruce D.; Smith, David V.; Deszcz-Pan, Maryla; Blome, Charles D.; Hill, Patricia

    2011-01-01

    This report is a digital data release for multiple geophysical surveys conducted in the Hunton anticline area of south-central Oklahoma. The helicopter electromagnetic and magnetic surveys were flown on March 16–17, 2007, in four areas of the Hunton anticline in south-central Oklahoma. The objective of this project is to improve the understanding of the geohydrologic framework of the Arbuckle-Simpson aquifer. The electromagnetic sensor for the helicopter electromagnetic survey consisted of six different transmitter-receiver orientations that measured the earth's electrical response at six distinct frequencies from approximately 500 Hertz to approximately 115,000 Hertz. The electromagnetic measurements were converted to electrical resistivity values, which were gridded and plotted on georeferenced maps. The map from each frequency represents a different depth of investigation for each area. The range of subsurface investigation is comparable to the depth of shallow groundwater. The four areas selected for the helicopter electromagnetic study, blocks A–D, have different geologic and hydrologic settings. Geophysical and hydrologic information from U.S. Geological Survey studies are being used by modelers and resource managers to develop groundwater resource plans for the Arbuckle-Simpson aquifer.

  1. Three-dimensional geologic model of the Arbuckle-Simpson aquifer, south-central Oklahoma

    USGS Publications Warehouse

    Faith, Jason R.; Blome, Charles D.; Pantea, Michael P.; Puckette, James O.; Halihan, Todd; Osborn, Noel; Christenson, Scott; Pack, Skip

    2010-01-01

    The Arbuckle-Simpson aquifer of south-central Oklahoma encompasses more than 850 square kilometers and is the principal water resource for south-central Oklahoma. Rock units comprising the aquifer are characterized by limestone, dolomite, and sandstones assigned to two lower Paleozoic units: the Arbuckle and Simpson Groups. Also considered to be part of the aquifer is the underlying Cambrian-age Timbered Hills Group that contains limestone and sandstone. The highly faulted and fractured nature of the Arbuckle-Simpson units and the variable thickness (600 to 2,750 meters) increases the complexity in determining the subsurface geologic framework of this aquifer. A three-dimensional EarthVision (Trademark) geologic framework model was constructed to quantify the geometric relationships of the rock units of the Arbuckle-Simpson aquifer in the Hunton anticline area. This 3-D EarthVision (Trademark) geologic framework model incorporates 54 faults and four modeled units: basement, Arbuckle-Timbered Hills Group, Simpson Group, and post-Simpson. Primary data used to define the model's 54 faults and four modeled surfaces were obtained from geophysical logs, cores, and cuttings from 126 water and petroleum wells. The 3-D framework model both depicts the volumetric extent of the aquifer and provides the stratigraphic layer thickness and elevation data used to construct a MODFLOW version 2000 regional groundwater-flow model.

  2. The role of sandstone in the development of an Ozark karst system, south-central Missouri

    USGS Publications Warehouse

    Orndorff, R.C.; Weary, D.J.; Harrison, R.W.

    2006-01-01

    Cave, spring, and sinkhole development in the Ozarks of south-central Missouri is placed in a geologic framework through detailed geologic mapping. Geologic mapping shows that initial dissolution and inception of cave development is concentrated just beneath sandstone beds within Upper Cambrian and Lower Ordovician dolostone. Although rocks of the Ozarks have systematic and pervasive vertical joints, the development of karst conduits is controlled by bedding planes and stratigraphic variability. In the Salem Plateau of south-central Missouri, sinkholes occur in the lower part of the Ordovician Roubidoux Formation, where sinkholes are rimmed with and contain sandstone that has collapsed into voids in the underlying Ordovician Gasconade Dolomite. Cave diving by the Ozark Cave Diving Alliance into Alley Spring, a large (average flow 3.7 m3/s) spring along the Jacks Fork in the Ozark National Scenic Riverways, shows that although the spring discharges from the middle part of the Gasconade, the source of water is a cave passage just beneath the Gunter Sandstone Member of the Gasconade Dolomite. Artesian conditions cause the upward movement of groundwater from cavernous dolostone beneath the sandstone aquitards to the large springs. We hypothesize that sandstone, which is largely impermeable due to silica cementation, acts as a confining unit where hydraulic pressure, combined with mixing of water of differing chemistry, increases dissolution in the underlying dolostone beds. ?? 2006 Geological Society of America.

  3. Hydrology of Lake June in winter, Highlands County, South-central Florida

    USGS Publications Warehouse

    Belles, Roger G.; Martin, Edward H.

    1985-01-01

    Lake June in Winter is in central Highlands County near the town of Lake Placid in south-central Florida. Recreation and citrus-grove irrigation are the major uses of lake water. Land use around the lake is residential citrus, and undeveloped. Most of the land use in the 44-square mile lake-drainage area is undeveloped. The surface area of the lake is approximately 5.7 square miles with water-surface altitude average of 74 feet. The extremes in lake altitude for the period 1945-82 were 77.58 feet in October 1948, and 71.62 feet in May 1981. Flow into Lake June in Winter is from Lake Placid to the south through Catfish Creek. Flow out of the Lake is northward through Stearns Creek to Lake Francis, and eventually by Josephine Creek to Lake Istokpoga. The quality of water in Lake June in Winter is good. Specific conductance was found to be generally low, ranging between 90 umho/cm to 170 umho/cm, indicating a lack of dissolved solids present in the lake. The lake is clear, with transparency values between 3 and 14 feet. Total nitrogen was found to be 0.60 mg/L indicating a minimal effect from nitrogen fertilizer washoff or septic-tank discharge. (USGS)

  4. Mosquito biodiversity patterns around urban environments in South-central okinawa island, Japan.

    PubMed

    Hoshi, Tomonori; Imanishi, Nozomi; Higa, Yukiko; Chaves, Luis Fernando

    2014-12-01

    Okinawa is the largest, most urbanized, and densely populated island in the Ryukyus Archipelago, where mosquito species diversity has been thoroughly studied. However, the south-central Okinawa mosquito fauna has been relatively poorly studied. Here, we present results from a mosquito faunal survey in urban environments of Nishihara city, south-central Okinawa. Mosquitoes were sampled biweekly, from April 2007 to March 2008, at 3 different environments: a forest preserve, an animal farm, and a water reservoir. We employed 4 mosquito collection methods: 1) oviposition traps; 2) light traps; 3) sweep nets; and 4) larval surveys of tree holes, leaf axils, and artificial water containers. We collected a total of 568 adults and 10,270 larvae belonging to 6 genera and 13 species, including 6 species of medical importance: Aedes albopictus, Armigeres subalbatus, Anopheles Hyrcanus group, Culex bitaeniorhynchus, Cx. quinquefasciatus, and Cx. tritaeniorhynchus. Mosquito species composition was similar to data from previous studies in Okinawa Island. The flattening of the species accumulation curve suggests that our diversity sampling was exhaustive with light and oviposition traps, as well as the coincidence between the species richness we found in the field and estimates from the Chao2 index, a theoretical estimator of species richness based on species abundance. This study highlights the importance of combining several sampling techniques to properly characterize regional mosquito fauna and to monitor changes in the presence of mosquito species.

  5. Lead in drinking water: sampling in primary schools and preschools in south central Kansas.

    PubMed

    Massey, Anne R; Steele, Janet E

    2012-03-01

    Studies in Philadelphia, New York City, Houston, Washington, DC, and Greenville, North Carolina, have revealed high lead levels in drinking water. Unlike urban areas, lead levels in drinking water in suburban and rural areas have not been adequately studied. In the study described in this article, drinking water in primary schools and preschools in five suburban and rural south central Kansas towns was sampled to determine if any exceeded the U.S. Environmental Protection Agency (U.S. EPA) guidance level for schools and child care facilities of 20 parts per billion (ppb). The results showed a total of 32.1% of the samples had detectable lead levels and 3.6% exceeded the U.S. EPA guidance level for schools and child care providers of 20 ppb. These results indicate that about one-third of the drinking water consumed by children age six and under in the five suburban and rural south central Kansas towns studied has some lead contamination, exposing these children to both short-term and long-term health risks. The authors suggest a need for increased surveillance of children's drinking water in these facilities.

  6. Diet, dietary selectivity and density of South American Grey Fox, Lycalopex griseus, in Central Chile.

    PubMed

    Muñoz-Pedreros, Andrés; Yáñez, José; Norambuena, Heraldo V; Zúñiga, Alfredo

    2017-03-06

    The South American Grey Fox (Lycalopex griseus) is a canid widely distributed in southern South America, however some aspects of its biology are still poorly known. We studied the diet and density of L. griseus in the Lago Peñuelas Biosphere Reserve, in Central Chile. The trophic niche breadth was B = 6.16 (Bsta = 0.47) and prey diversity was H ' = 2.46 (Hmax' = 3.17, J' = 0.78). The highest proportions of prey consumed in the diet were Oryctolagus cuniculus (52.21%) and other mammals (32.78%). We compared these results with a latitudinal gradient of diet results for this species in Chile. L. griseus eats mostly mammals (> 90% of total prey), consuming the rodent Phyllotis darwini and reptiles in the Northern zone; O. cuniculus, Octodon degus and Abrocoma bennetti in the Central zone; Abrothrix spp. and lagomorphs in the Southern zone; and Lepus capensis and Ovis aries in the Austral zone. The estimated density of L. griseus in Lago Peñuelas NR was 1.3 foxes /km(2) . This article is protected by copyright. All rights reserved.

  7. U.S. Department of the Interior South Central Climate Science Center

    USGS Publications Warehouse

    Shipp, Allison A.

    2012-01-01

    On September 14, 2009, the Secretary of the Interior signed a Secretarial Order (No. 3289) entitled, "Addressing the Impacts of Climate Change on America's Water, Land, and Other Natural and Cultural Resources." The Order effectively established the U.S. Department of the Interior (DOI) Climate Science Centers (CSCs) for the purpose of integrating DOI science and management expertise with similar contributions from our partners to provide information to support strategic adaptation and mitigation efforts on public and private lands across the United States and internationally. The South Central Climate Science Center (SC CSC) is supported by a consortium of partners that include The University of Oklahoma, Texas Tech University, Louisiana State University, The Chickasaw Nation, The Choctaw Nation of Oklahoma, Oklahoma State University, and the National Oceanic and Atmospheric Administration's Geophysical Fluid Dynamics Laboratory. Additionally, the SC CSC will collaborate with a number of other universities, State and federal agencies, and nongovernmental organizations (NGOs) with interests and expertise in climate science. The primary partners of the SC CSC are the Landscape Conservation Cooperatives (LCCs), which include the Desert, Eastern Tallgrass Prairie and Big Rivers, Great Plains, Gulf Coast Prairie, Gulf Coastal Plains and Ozarks, and Southern Rockies. CSC collaborations are focused on common science priorities that address priority partner needs, eliminate redundancies in science, share scientific information and findings, and expand understanding of climate change impacts in the south-central United States and Mexico.

  8. Interseismic strain accumulation in seismic gap of south central Chile from GPS measurements

    NASA Astrophysics Data System (ADS)

    Rudloff, A.; Vigny, C.; Ruegg, J. C.; Campos, J.

    2003-04-01

    Three campaigns of Global Positioning System (GPS) measurements were carried out in the Concepcion-Constitucion seismic gap in South Central Chile in 1996, 1999, and 2002. We observed a network of about 40 sites, made of 2 east-west transects roughly perpendicular to the trench ranging from the coastal area to the Argentina border and 1 north-south profile along the coast. Data sets were processed with MIT's GAMIT/GLOBK package. Horizontal velocities have formal uncertainties around 1 to 2 mm/yr in average. Vertical velocities are also determined and have uncertainties around 2 to 5 mm/yr. We find that the convergence between Nazca and South-America plates better matches the pole previously estimated by (Larson et al, 1997) than the Nuvel-1A estimate. Our estimate predicts a convergence of 72 mm/yr at N70 to be compared with Nuvel-1A 80 mm/yr at N79. With respect to stable South America, horizontal velocities decrease from 35 mm/yr on the coast to 14 mm/yr in the Cordillera. Vertical velocities help constraint lithospheric flecture. Partionning of the slightly oblique convergence will be investigated. The gradient of convergent parallel velocities reflects aseismic elastic loading on a zone of about 400 km width. Interestingly enough, this gradient exhibit a linear pattern, marginally compatible with the expected arctangent shape. 70 mm/yr of motion accumulated since the last big event in this area (1835 Earthquake described by Darwin) represent more than 10 m of displacement. Therefore, this area is probably mature for a next large earthquake, the magnitude of which could reach 8.5.

  9. A Storm-by-Storm Analysis of Alpine and Regional Precipitation Dynamics at the Mount Hunter Ice Core Site, Denali National Park, Central Alaska Range

    NASA Astrophysics Data System (ADS)

    Saylor, P. L.; Osterberg, E. C.; Kreutz, K. J.; Wake, C. P.; Winski, D.

    2014-12-01

    In May-June 2013, an NSF-funded team from Dartmouth College and the Universities of Maine and New Hampshire collected two 1000-year ice cores to bedrock from the summit plateau of Mount Hunter in Denali National Park, Alaska (62.940291, -151.087616, 3912 m). The snow accumulation record from these ice cores will provide key insight into late Holocene precipitation variability in central Alaska, and compliment existing precipitation paleorecords from the Mt. Logan and Eclipse ice cores in coastal SE Alaska. However, correct interpretation of the Mt. Hunter accumulation record requires an understanding of the relationships between regional meteorological events and micrometeorological conditions at the Mt. Hunter ice core collection site. Here we analyze a three-month window of snow accumulation and meteorological conditions recorded by an Automatic Weather Station (AWS) at the Mt. Hunter site during the summer of 2013. Snow accumulation events are identified in the Mt. Hunter AWS dataset, and compared on a storm-by-storm basis to AWS data collected from the adjacent Kahiltna glacier 2000 m lower in elevation, and to regional National Weather Service (NWS) station data. We also evaluate the synoptic conditions associated with each Mt. Hunter accumulation event using NWS surface maps, NCEP-NCAR Reanalysis data, and the NOAA HYSPLIT back trajectory model. We categorize each Mt. Hunter accumulation event as pure snow accumulation, drifting, or blowing snow events based on snow accumulation, wind speed and temperature data using the method of Knuth et al (2009). We analyze the frequency and duration of events within each accumulation regime, in addition to the overall contribution of each event to the snowpack. Preliminary findings indicate that a majority of Mt. Hunter accumulation events are of pure accumulation nature (55.5%) whereas drifting (28.6%) and blowing (15.4%) snow events play a secondary role. Our results will characterize the local accumulation dynamics on

  10. Metamorphic facies map of Alaska

    SciTech Connect

    Dusel-Bacon, C.; O-Rourke, E.F.; Reading, K.E.; Fitch, M.R.; Klute, M.A.

    1985-04-01

    A metamorphic-facies of Alaska has been compiled, following the facies-determination scheme of the Working Group for the Cartography of the Metamorphic Belts of the World. Regionally metamorphosed rocks are divided into facies series where P/T gradients are known and into facies groups where only T is known. Metamorphic rock units also are defined by known or bracketed age(s) of metamorphism. Five regional maps have been prepared at a scale of 1:1,000,000; these maps will provide the basis for a final colored version of the map at a scale of 1:2,500,000. The maps are being prepared by the US Geological Survey in cooperation with the Alaska Division of Geological and Geophysical Surveys. Precambrian metamorphism has been documented on the Seward Peninsula, in the Baird Mountains and the northeastern Kuskokwim Mountains, and in southwestern Alaska. Pre-Ordovician metamorphism affected the rocks in central Alaska and on southern Prince of Wales Island. Mid-Paleozoic metamorphism probably affected the rocks in east-central Alaska. Most of the metamorphic belts in Alaska developed during Mesozoic or early Tertiary time in conjuction with accretion of many terranes. Examples are Jurassic metamorphism in east-central Alaska, Early Cretaceous metamorphism in the southern Brooks Range and along the rim of the Yukon-Kovyukuk basin, and late Cretaceous to early Tertiary metamorphism in the central Alaska Range. Regional thermal metamorphism was associated with multiple episodes of Cretaceous plutonism in southeastern Alaska and with early Tertiary plutonism in the Chugach Mountains. Where possible, metamorphism is related to tectonism. Meeting participants are encouraged to comment on the present version of the metamorphic facies map.

  11. Accretion of southern Alaska

    USGS Publications Warehouse

    Hillhouse, J.W.

    1987-01-01

    Paleomagnetic data from southern Alaska indicate that the Wrangellia and Peninsular terranes collided with central Alaska probably by 65 Ma ago and certainly no later than 55 Ma ago. The accretion of these terranes to the mainland was followed by the arrival of the Ghost Rocks volcanic assemblage at the southern margin of Kodiak Island. Poleward movement of these terranes can be explained by rapid motion of the Kula oceanic plate, mainly from 85 to 43 Ma ago, according to recent reconstructions derived from the hot-spot reference frame. After accretion, much of southwestern Alaska underwent a counterclockwise rotation of about 50 ?? as indicated by paleomagnetic poles from volcanic rocks of Late Cretaceous and Early Tertiary age. Compression between North America and Asia during opening of the North Atlantic (68-44 Ma ago) may account for the rotation. ?? 1987.

  12. New Vitrinite Reflectance Data for the Bighorn Basin, North-Central Wyoming and South-Central Montana

    USGS Publications Warehouse

    Finn, Thomas M.; Pawlewicz, Mark J.

    2007-01-01

    Introduction The Bighorn Basin is a large Laramide (Late Cretaceous through Eocene) structural and sedimentary basin that encompasses about 10,400 mi2 in north-central Wyoming and south-central Montana (fig. 1). Important conventional oil and gas resources have been discovered and produced from reservoirs ranging in age from Cambrian through Tertiary (Fox and Dolton, 1989, 1996a, b; De Bruin, 1993). In addition, a potential unconventional basin-centered gas accumulation may be present in Cretaceous reservoirs (Johnson and Finn, 1998; Johnson and others, 1999). The purpose of this report is to present new vitrinite reflectance data to be used in support of the U.S Geological Survey's assessment of undiscovered oil and gas resources of the Bighorn Basin. These new data supplement previously published data by Nuccio and Finn (1998), and Yin (1997), and lead to a better understanding and characterization of the thermal maturation and burial history of potential source rocks. Eighty-nine samples of Cretaceous and Tertiary strata (fig. 2) were collected and analyzed - 15 samples were from outcrops around the margins of the basin and 74 samples were well cuttings (fig. 1). Forty-one of the samples were shale, two were carbonaceous shale, and the remainder from coal. All samples were analyzed by vitrinite reflectance to determine levels of thermal maturation. Preparation of samples for reflectance analysis required (1) crushing the larger pieces into 0.25-to 1-mm pieces, (2) casting the pieces with epoxy in pre-cut and drilled plugs, and (3) curing the samples overnight. Subsequently, a four-step grinding and polishing process was implemented that included sanding with progressively finer sandpaper (60 and 600 grit) followed with a two-step polishing process (0.3 and 0.05 micron). Vitrinite reflectance measurements were determined at 500 X magnification using plane-polarized incident white light and a 546-nm monochromatic filter in immersion oil. For samples containing

  13. Permafrost thaw in upland catchments of central Alaska: groundwater connection and landscape evolution as discerned from U isotopes and dissolved organic carbon

    NASA Astrophysics Data System (ADS)

    Ewing, S. A.; O'Donnell, J. A.; Paces, J. B.; Jorgenson, M. T.; Kanevskiy, M. Z.; Harden, J. W.; Aiken, G.; Striegl, R. G.

    2009-12-01

    Permafrost thaw mobilizes carbon and transforms hydrologic flowpaths, with the potential for large feedback effects on climate. Permafrost thaw also results in poorly quantified geomorphic effects that depend on ground ice volumes, sediment texture, and thermal effects of thaw waters. Here we use 234U/238U activity ratios (ARs) to indicate the influence of deep groundwater following fire-induced permafrost thaw in geologically distinct upland catchments in central Alaska. The 234U/238U AR in water or ice increases as a function of contact time with sediment, at a rate that depends on sediment and water U concentrations, surface area, and sediment/water ratio. Combining U series data with solute concentrations for soil porewaters, shallow permafrost and surface streams, we make inferences about the influence of recent thaw (last 100 y) on landscapes, hydrology and dissolved organic carbon (DOC) dynamics in central Alaska. In a loess-dominated catchment where ice-rich silt is present to depths of up to 25 m, the depth of fire-induced thaw is limited to ~50 cm. DOC concentrations in surface waters and soil porewaters showed little seasonal or spatial variation (40±7 ppm in spring and fall 2008) and were positively correlated with solutes indicating mineral contact in fall 2008. In soil porewaters, surface waters and upper permafrost (2 m depth), 234U/238U ARs (1.15-1.27) were lower than those in deep permafrost (up to 1.55) and groundwater (1.54), suggesting no deep thaw or connection to deeper groundwater regardless of time-since-fire. Shallow thaw and soil wetting allowed for post-fire recovery of shallow permafrost and hence black spruce communities on the order of 100 y. Yet we observed landscape responses to thaw including thermokarst pits and channels, bank collapse, and stream incision, suggesting longer-term landscape equilibration. By contrast, in a colluvium-dominated catchment, gravelly textures allow better drainage of thaw water, resulting in deep thaw

  14. Ground-water resources of the St. James area, South-central Minnesota

    USGS Publications Warehouse

    Ropes, L.H.

    1969-01-01

    The purpose of this investigation was to evaluate the quality and quantity of the ground-water resources in the area of St. James, Minnesota. St. James is located in the center of Watonwan County in south-central Minnesota. The area is covered by a thick layer of glacial drift which is underlain by Cretaceous, Cambrian, and Precambrian rocks. St. James presently obtains its water supply from two aquifers. One is a Cretaceous sandstone 160 feet below the surface, in which two wells are completed. This aquifer yields abundant water but it is of poor quality and is expensive to treat. The second source, tapped by three municipal wells, is a surficial sand and gravel deposit less than 40 feet thick at the well field. This aquifer produces water of better quality, but its extent and capacity are not known. There are other wells in the area completed at depths ranging from 15 to 500 feet.

  15. Salt-dome locations in the Gulf Coastal Plain, South-Central United States

    USGS Publications Warehouse

    Beckman, J.D.; Williamson, A.K.

    1990-01-01

    Information on salt domes in Gulf of Mexico Coastal Plain, south-central United States and the adjacent Continental Shelf were compiled from major published sources, 1973-84. The location of 624 salt domes is shown on a map at a scale of 1:1 ,500,000. A color-coding system was used to show that the occurrence, size, shape, and location of these domes varies among sources. Two tables of additional data accompany the map and include other available information such as: identifying sources, depth to salt and caprock, diameter, volume, name, and uppermost zone of surrounding sediment that is penetrated, as well as the number of matches between sources. The locations of salt domes that penetrate specific zones within the gulf coast regional aquifer system are shown on maps. (USGS)

  16. Hydrologic reconnaissance of the Kolob, Alton, and Kaiparowits Plateau coal fields, south-central Utah

    USGS Publications Warehouse

    Plantz, Gerald G.

    1985-01-01

    The study area in south-central Utah (fig. 1) is noted for its large coal reserves in the Alton, Kolob, and Kaiparowits Plateau coal fields. The area also is noted for its scenic beauty and general scarcity of water. Although there has been very little development of the coal resources through 1983, there is a potential for large-scale development with both surface- and underground-mining methods. Mining of coal could have significant effects on the quantity and quality of the water resources. The purpose of this atlas is to define the surface- and ground-water resources of the area and to identify the potential effects on these resources by coal mining.

  17. Digital data from the Great Sand Dunes airborne gravity gradient survey, south-central Colorado

    USGS Publications Warehouse

    Drenth, B.J.; Abraham, J.D.; Grauch, V.J.S.; Labson, V.F.; Hodges, G.

    2013-01-01

    This report contains digital data and supporting explanatory files describing data types, data formats, and survey procedures for a high-resolution airborne gravity gradient (AGG) survey at Great Sand Dunes National Park, Alamosa and Saguache Counties, south-central Colorado. In the San Luis Valley, the Great Sand Dunes survey covers a large part of Great Sand Dunes National Park and Preserve. The data described were collected from a high-resolution AGG survey flown in February 2012, by Fugro Airborne Surveys Corp., on contract to the U.S. Geological Survey. Scientific objectives of the AGG survey are to investigate the subsurface structural framework that may influence groundwater hydrology and seismic hazards, and to investigate AGG methods and resolution using different flight specifications. Funding was provided by an airborne geophysics training program of the U.S. Department of Defense's Task Force for Business & Stability Operations.

  18. Cephalopods and cetaceans as indicators of offshore bioavailability of cadmium off Central South Brazil Bight.

    PubMed

    Dorneles, Paulo Renato; Lailson-Brito, José; Dos Santos, Roberta Aguiar; Silva da Costa, Paulo Alberto; Malm, Olaf; Azevedo, Alexandre Freitas; Machado Torres, João Paulo

    2007-07-01

    Regarding Brazilian coast, industrial and urban developments are concentrated along Central South Brazil Bight. Samples from inshore and offshore species from the concerned area were analyzed, comprising 24 cetaceans (9 species) and 32 squids (2 species). Cadmium was determined by GFAAS and our results were in agreement with certified values (DOLT-2, NRCC). Mean cadmium concentration (in microg/g, wet weight) observed in the digestive gland of sexually mature Argentine short-finned squids (Illex argentinus) was 1002.9. To our knowledge this is the highest cadmium level ever reported for a cephalopod. Concerning cetaceans, our results include one of the highest renal cadmium concentrations described for striped dolphins (71.29 microg/g, wet weight). Anthropogenic action, upwelling and cannibalism of Argentine short-finned squid on the studied area are possible reasons for such remarkable cadmium concentrations.

  19. Oil and gas developments in South America, Central America, Caribbean area, and Mexico in 1985

    SciTech Connect

    Wiman, W.D.

    1986-10-01

    Exploration activity in South America, Central America, the Caribbean area, and Mexico in 1985 was concentrated in proven petroleum provinces. Successful exploration and development efforts were most intense in Colombia and Venezuela, where activity centered around the Cano Limon field area. Initial production of 30,000 BOPD from Cano Limon started in December, raising Colombia again to the ranks of an exporting nation. Another significant discovery in Colombia was San Francisco field in the Upper Magdalena basin. Argentina reported significant discoveries by YPF in the Northwest Cretaceous and Neuquen basins and by Total offshore Tierra del Fuego. Brazil continued to discover major reserves in the offshore Campos basin in ever-increasing water depths. At year end, Venezuela was drilling Furrial-1 in eastern Venezuela. The well is reported to be the outstanding discovery of 1985, if not of the last 2 decades. 4 figures, 7 tables.

  20. Farm crisis and rural revitalization in south-central New York during the early twentieth century.

    PubMed

    Osterud, Grey

    2010-01-01

    In contrast to both the critique of rural backwardness made by the Country Life Movement and the lament about rural declension expressed by proponents of agrarianism, the history of the Nanticoke Valley of south-central New York State demonstrates the possibilities for rural revitalization that lay in connections between the countryside and the city. In the early twentieth century, as long-settled families departed for urban employment, European immigrant families escaping the mines and mills bought abandoned farms. Motorized transport enabled farming families to send household members to the city each day and furnished them with a local market for their produce. This flexible combination of subsistence production, wage labor, and petty commodity production revitalized the rural economy and sustained the community in spite of the consolidation of the dairy industry. This essay explores the social changes that accompanied this profound reorientation of local life.

  1. The Protective Effects of Adolescent Motherhood in South Central Appalachia: Salvation From Drugs and Emptiness.

    PubMed

    Dalton, Elizabeth D

    2015-09-01

    This study qualitatively explored the meaning of teenage motherhood to young Appalachian mothers. Fourteen in-depth interviews at the homes of mothers between the ages of 18 and 22 from the South Central Appalachian region were conducted. Findings indicate that teenage motherhood is symbolically reproduced by filling a void and providing escape from the drug culture. Analysis of these findings indicates that the meaning of motherhood is characterized by salvation. This salvation is shaped by the emotional chasm that motherhood fills, as well as the protective barrier it provides between the mother and the surrounding drug culture. Implications of these findings might include a need to examine the protective effects of motherhood from negative sociocultural forces among other subcultures. Also, the pervasive drug culture that surrounds young people in Appalachia should be taken into consideration when shaping policy and interventions for teenage pregnancy prevention.

  2. Oil and gas developments in South America, Central America, Caribbean area, and Mexico in 1986

    SciTech Connect

    Wiman, W.D.

    1987-10-01

    Exploration activity in South America, Central America, the Caribbean area, and Mexico in 1986 was considerably reduced compared to 1985. Brazil, Colombia, Ecuador, Guatemala, and Venezuela had increased oil production, with Colombia showing a dramatic 71% increase attributed mainly to bringing on-stream the pipeline connecting Occidental-Shell-Ecopetrol's Cano Limon complex to the port of Covenas. Significant discoveries were reported from Argentina in the Olmedo, Oran, and San Jorge basins; Brazil in the offshore Campos and Amazon basins; Colombia in the Llanos basin; Ecuador in the Oriente basin; Mexico in the Bay of Campeche; Peru in the Ucayali basin; and Venezuela in the Eastern Venezuela basin. Eastern Venezuela's Furrial discovery is reported to have recoverable reserves of more than 1 million bbl of oil, and Shell's Ucayali basin discovery is reported to hold more than 7 tcf of gas. 7 figures, 10 tables.

  3. Tectonic framework of petroliferous rocks in Alaska: hydrocarbons

    USGS Publications Warehouse

    Grantz, Arthur; Kirschner, C.E.

    1976-01-01

    Alaska, which contains about 28% of the land and continental shelf of the United States, is estimated by the U.S. Geological Survey to contain about one third of the nation's undiscovered oil and about one sixth of its undiscovered natural gas. The Survey estimates that fields discovered in Alaska through 1972 ultimately may produce about 26 billion bbl of oil and 68 Tcf of natural gas. In northern Alaska, Paleozoic and Mesozoic shelf and slope carbonate and clastic rocks of the Brooks Range orogen were thrust relatively northward over the depressed south margin of the Paleozoic and Mesozoic Arctic platform. A foredeep, the Colville geosyncline, developed across the depressed margin of the platform in earliest Cretaceous time. Detritus from the Brooks Range filled the foredeep and prograded northward to fill the Cretaceous and Tertiary North Chukchi and Umiat-Camden basins and form the progradational Beaufort shelf. The largest petroleum reserves (Prudhoe Bay and associated fields) and the best prospects for additional large discoveries in Alaska lie in the areally extensive upper Paleozoic to Tertiary carbonate and clastic rocks of northern Alaska. In southern Alaska, a series of arc-trench systems developed on oceanic rocks during Jurassic and Cretaceous time. Between these arcs and the metamorphic (continental) terranes of east-central and northern Alaska, large back-arc and arc-trench gap basins received thick volcanic and detrital deposits. These deposits were extensively, and commonly intensely, deformed and disrupted by mid-Jurassic to Tertiary plutonism, Laramide oroclinal bending, wrench faulting, and arc-related compression. This deformation, coupled with low porosity (in part produced by diagenetic mobilization of labile constituents), has left these rocks with only modest, local prospects for petroleum. Laramide events compressed and consolidated ("continentalized") the late Mesozoic back-arc basin deposits and welded them to the older continental

  4. The opening of central segment of the South Atlantic: symmetry and the extension discrepancy

    NASA Astrophysics Data System (ADS)

    Reston, Timothy

    2010-05-01

    The rifted margins of the central segment of the South Atlantic are considered in terms of magmatism, symmetry and the amount and timing of extension, in comparison to the margins of the North Atlantic. I set out to explain the apparent lack of significant faulting in the pre-salt "sag basins" observed on these margins and the inferred transition from terrestrial to lacustrine to evaporitic to open marine sedimentation. It is suggested that the South Atlantic margins are probably moderately magmatic, with most of the magmatism occurring in the Hauterivian-Barremian, after the onset of rifting in the Berriasian. Most of the crustal extension also took place between the Berriasian and Hauterivian, before focusing along a narrow line of breakup in the Aptian that cut obliquely across the earlier rift structures. The changing locus of the rifting with time led to the development of considerable asymmetry, and the stranding of the large part of the salt basins on variously the African and South American margin. The amount of Berriasian-Hauterivian extension may have been underestimated and may be sufficient to explain the majority of the observed crustal thinning. An apparent subsidence deficit by the time of the deposition of the Aptian evaporites is a likely consequence of either delayed thermal subsidence due to the influx of hot asthenosphere or the effect of a local water level in the isolated early Cretaceous basin well below global sealevel throughout both lacustrine and evaporitic deposition. No erosional unconformity resulting from drawdown is observed as no drawdown occurred: the basin developed with the subdued topography of a subaerial rift before being gradually invaded by seawater during the Aptian (leading to the evaporite sequences), with the transgression leading to open marine conditions in the Albian.

  5. Tectonic geomorphology of the south-central Appalachians: The influence of Triassic extension

    SciTech Connect

    Webb, J.A. . Geology Dept.); Henika, W.S. . Division of Mineral Resources)

    1994-03-01

    During the final phase of the Alleghanian Orogeny, which ended probably in the mid-Permian, intense thrusting created a high mountain range with relief of up to 4.5 km and a width of 250--300 km. The drainage divide presumably lay within the Piedmont or Blue ridge Provinces, and probably ran subparallel to the present-day mid-Atlantic coastline. In the Middle and Late Triassic this mountain range was disrupted by the initial phases of rifting between the African and North American Plates. Many of the Alleghanian thrusts were reactivated as listric normal faults, creating a series of long, narrow asymmetric half grabens, and resulting in extensive delamination and thinning of the crust, particularly in the eastern Piedmont. South of the Salisbury Embayment the western limit of the Triassic basins steps consistently eastward, mirroring the offset of the ocean floor anomalies south of the Bermuda Fault Zone. The offset is also reflected by the easterly displacement of the present-day Appalachian drainage divide in southern virginia. This strongly suggests that the divide is largely inherited from the Triassic faulting episode. Rivers flowing westwards from the present-day Appalachians, including those like the New River crossing the Valley and Ridge Province, have retained more or less their pre-Triassic orientation, when they flowed down the western flanks of the Alleghanian mountains. The Triassic basins were separated by coast-parallel ranges with as much as 1 km of relief; these were largely eroded in the mid-Jurassic, so that by the Early Cretaceous the south-central Appalachians had more or less their present appearance. Subsequent erosion has probably resulted in westward retreat of the drainage divide.

  6. Seismic structure in central Mexico: Possible fragmentation of the subducted South Cocos plate

    NASA Astrophysics Data System (ADS)

    Dougherty, S. L.; Clayton, R. W.

    2012-12-01

    The fine-scale seismic structure of the central Mexico subduction zone is studied using moderate-sized (M4-6) intraslab earthquakes. Regional waveforms from the Meso America Subduction Experiment (MASE), Veracruz-Oaxaca (VEOX), and Servicio Sismológico Nacional (SSN) seismic arrays are complicated and contain detailed information about the subduction zone structure, including evidence of lateral heterogeneity. This waveform information is used to model the structure of the subducted plate, particularly along the transition from flat to normal subduction located to the east of the MASE array. Based on the results of plate motion studies showing that the Cocos plate moves differently on either side of the Orozco Fracture Zone (OFZ) coupled with our own structural modeling results across the flat-to-normal slab transition west of the MASE array, we recently proposed that the Cocos slab is currently fragmenting into a North Cocos plate and a South Cocos plate along the eastern projection of the OFZ. In the east, observations of a sudden change in slab dip combined with the abrupt end of the Trans Mexican Volcanic Belt suggest a second possible slab tear located within the South Cocos plate. The eastern lateral extent of a thin ultra-slow velocity layer (USL) imaged atop the Cocos slab in recent studies along the MASE array is examined here using MASE, VEOX, and SSN waveforms to test if the USL ends along a lineament related to the potential slab tear. We observe changes in waveform complexity across the sharp transition in slab dip, which may indicate a possible tear in the South Cocos plate. We perform 1D and 2D waveform modeling in order to image the structure of the slab and overriding plate in this region. The tears could indicate a slab rollback mechanism in which separate slab segments move independently.

  7. Characterization and geochemistry of Devonian oil shale North Alabama - South Central Tennessee

    USGS Publications Warehouse

    Rheams, K.F.; Neathery, T.L.

    1984-01-01

    Based on the physical and chemical data obtained to date, the Devonian oil shale rock of north Alabama and south-central Tennessee appears to offer an attractive potential for future resource development. The shale rock appears to have formed in a restrictive marine environment which provided opportunity for the accumulation of marine organic matter to form sufficient kerogen. The shale contains approximately 18% to 22% organic matter which is primarily kerogen. The kerogen has a relatively high H:C ratio indicative of an alginite and/or exinite source (Type 1 and Type II kerogen) and a high proportion of alkane and saturated ring hydrocarbons. However, a few samples have low H:C ratio values and are interpreted to have been formed in a shallow water oxidizing environment. Also, there is a possibility that these low H:C values may represent mixtures of terrestrial and marine organic material suggesting lateral facies changes of the rock from marine to near shore depositional environments. Trace metal values for both the whole rock and the shale oil fraction indicate a generally high V:Ni ratio, also indicative of a marine environment. Other trace metal values are in good agreement with data from other Devonian shales. Throughout the north Alabama and south-central Tennessee study area, the average oil yield from the shale is 13.9 gallon per ton. The highest oil yield values were obtained from the middle and upper parts of the shale sequence. Based on the crude oil composition diagram (11), the Alabama-Tennessee shale oil is classified as a aromatic-intermediate oil Estimated reserves of inplace shale oil resources in the principal study area, under less than 200 feet of overburden, exceeds 12.5 billion barrels.

  8. Paleotectonic implications of arkose beds in Park Shale (Middle Cambrian), Bridger Range, south-central Montana

    SciTech Connect

    Fryxell, J.C.; Smith, D.L.

    1983-08-01

    The Cambrian System in the Bridger Range of south-central Montana is part of a 450 to 500-m (1475 to 1640-ft) thick transgressive-regressive sequence of fine-grained clastic and carbonate rocks. In south-central Montana, the Park Shale is 50 m (165 ft) of green, micaceous shale with interbedded siltstone at the base and intercalated limestone at the top. However, in the northern Bridger Range, the lower 30 m (100 ft) is a prominent interval of interbedded arkosic sandstone and micaceous shale. These arkosic sandstone beds are localized in the northern Bridger Range and are unknown in the southern Bridgers and in Cambrian outcrops of surrounding areas. The occurrence of Park sandstone beds that contain orthoclase and plagioclase grains and pebbles of quartzofeldspathic gneiss requires 1) the presence of a localized island of Precambrian crystalline rock, an erosional remnant that must have risen at least 200 m (650 ft) above the surrounding Cambrian/Precambrian erosion surface and was exposed above the depositional interface through most of the Middle Cambrian, or 2) an island of Precambrian crystalline rock that was exposed by late Middle Cambrian reactivation of zones of Precambrian structural weakness. The most spatially and lithologically feasible tectonic feature along which late Middle Cambrian movement might have produced an island or series of islands is the Willow Creek-Jefferson Canyon fault zone, along which significant movement occurred during deposition of the LaHood Formation (Precambrian Y); the fault zone structurally divides the northern and southern parts of the Bridger Range, and later Paleozoic movement has been documented along this zone.

  9. Genetic Divergence Disclosing a Rapid Prehistorical Dispersion of Native Americans in Central and South America

    PubMed Central

    He, Yungang; Wang, Wei R.; Li, Ran; Wang, Sijia; Jin, Li

    2012-01-01

    An accurate estimate of the divergence time between Native Americans is important for understanding the initial entry and early dispersion of human beings in the New World. Current methods for estimating the genetic divergence time of populations could seriously depart from a linear relationship with the true divergence for multiple populations of a different population size and significant population expansion. Here, to address this problem, we propose a novel measure to estimate the genetic divergence time of populations. Computer simulation revealed that the new measure maintained an excellent linear correlation with the population divergence time in complicated multi-population scenarios with population expansion. Utilizing the new measure and microsatellite data of 21 Native American populations, we investigated the genetic divergences of the Native American populations. The results indicated that genetic divergences between North American populations are greater than that between Central and South American populations. None of the divergences, however, were large enough to constitute convincing evidence supporting the two-wave or multi-wave migration model for the initial entry of human beings into America. The genetic affinity of the Native American populations was further explored using Neighbor-Net and the genetic divergences suggested that these populations could be categorized into four genetic groups living in four different ecologic zones. The divergence of the population groups suggests that the early dispersion of human beings in America was a multi-step procedure. Further, the divergences suggest the rapid dispersion of Native Americans in Central and South Americas after a long standstill period in North America. PMID:22970308

  10. Petrogenesis of the Fifes Peak volcanics, south-central Cascades Range, Washington

    SciTech Connect

    Babcock, R.S.; Thompson, J.M.S. . Geology Dept.)

    1993-04-01

    During the late Oligocene (ca. 27--23 Ma.), a voluminous section of subduction-related basalt to rhyolite flows and interbedded pyroclastics, comprising the Fifes Peak Formation, were extruded in the south-central Cascades Range of Washington State. Microprobe analyses reveal that basalts and basaltic andesites contain megacrysts of aluminous clinopyroxene and spinel (hercynite) that may be xenocrysts derived from an upper mantle source zone or early, high pressure magmatic phases. Mass balance calculations indicate that the compositional variation of the Fifes Peak basalt and andesite was controlled mainly by high-pressure clinopyroxene-dominated fractionation, coupled with lower pressure fractionation of plagioclase + orthopyroxene + magnetite/ilmenite. Trace element data and mass balances also show that the more silicic lavas must contain a significant crustal component (such as a high Ba/Nb pelagic sediment). The dacites and rhyolites were probably formed mainly by crustal melting, rather than contamination of mantle-derived magmas. The Fifes Peak volcanics have a typical arc-type trace-element distribution with distinct depletions in Ta, Nb, and Ti and enrichment in Th and large-ion-lithophile elements. All of the analyzed Fifes Peak flows are light-rare-earth-element enrichment, with a mean La/Yb ratio of 7.6. There is no indication of an OIB mantle source array, nor the low fluid-flux subduction conditions that characterize magmas generated in the southwest Cascades. Apparently the anomalous nature of the subduction zone in that region of the Cascades arc does not extend northward to the south-central Cascades.

  11. Genetic divergence disclosing a rapid prehistorical dispersion of Native Americans in Central and South America.

    PubMed

    He, Yungang; Wang, Wei R; Li, Ran; Wang, Sijia; Jin, Li

    2012-01-01

    An accurate estimate of the divergence time between Native Americans is important for understanding the initial entry and early dispersion of human beings in the New World. Current methods for estimating the genetic divergence time of populations could seriously depart from a linear relationship with the true divergence for multiple populations of a different population size and significant population expansion. Here, to address this problem, we propose a novel measure to estimate the genetic divergence time of populations. Computer simulation revealed that the new measure maintained an excellent linear correlation with the population divergence time in complicated multi-population scenarios with population expansion. Utilizing the new measure and microsatellite data of 21 Native American populations, we investigated the genetic divergences of the Native American populations. The results indicated that genetic divergences between North American populations are greater than that between Central and South American populations. None of the divergences, however, were large enough to constitute convincing evidence supporting the two-wave or multi-wave migration model for the initial entry of human beings into America. The genetic affinity of the Native American populations was further explored using Neighbor-Net and the genetic divergences suggested that these populations could be categorized into four genetic groups living in four different ecologic zones. The divergence of the population groups suggests that the early dispersion of human beings in America was a multi-step procedure. Further, the divergences suggest the rapid dispersion of Native Americans in Central and South Americas after a long standstill period in North America.

  12. The Early Proterozoic structural and tectonic history of the south central Lake Superior Region

    NASA Astrophysics Data System (ADS)

    Ueng, Wen-Long C.; Larue, Dave K.

    1988-06-01

    The early Proterozoic tectonic evolution of the south central Lake Superior region is complex, owing to the presence of four tectonostratigraphic terranes, which were affected by six phases of deformation. The four terranes are the passive margin of the Superior craton, two paraautochthonous passive margin terranes (Crystal Falls and Florence-Niagara terranes), and a southern magmatic arc complex which is probably allochthonous with respect to the other terranes. Four of the six deformational episodes accompanied subhorizontal shortening, while two were caused by subvertical shortening. The first and the most penetrative phase of deformation is marked by subhorizontal shortening in a NNE-SSW direction. The second and fourth deformations were characterized by subvertical shortening and did not significantly modify the structural orientations from previous events in the study area. The third, fifth, and sixth deformations mostly caused open folding, and shortening directions were NW, NE, and W, respectively. Because all the terranes in the south central Lake Superior region share parallel deformational histories, it is suggested that the accretion of these terranes occurred during the first deformational episode. After removal of younger deformational effects, including open folding of the suture zone, the tectonostratigraphic assemblages in this region show the following sequence from NNE to SSW: a platformal assemblage overlying sialic basement, a basinal assemblage of tholeiitic volcanic rocks overlain by deep-water turbidites, an assemblage of basin floor deposits (Crystal Falls terrane) with apparently no demonstratably underlying crystalline basement, a fault-bounded terrane with highly strained passive margin strata (Florence-Niagara terrane), and a calc-alkaline magmatic arc assemblage. Such an arrangement of tectonostratigraphic assemblages is comparable with cross sections through Phanerozoic accretionary continental margins and therefore supports an arc

  13. Spatial and temporal interactions between livestock and wildlife in South Central Spain assessed by camera traps.

    PubMed

    Kukielka, E; Barasona, J A; Cowie, C E; Drewe, J A; Gortazar, C; Cotarelo, I; Vicente, J

    2013-11-01

    The diversification of livestock farms into hunting estates in South Central Spain (SCS) may impede the success of Mycobacterium bovis eradication programmes by facilitating transmission between wildlife and livestock. In this observational study we aimed to provide information of relevance about the nature and frequency of interactions (observed visits to study points) between livestock (cattle and domestic pigs) and wildlife (wild boar and red deer). The study was conducted in an extensive cattle farm in SCS where the land is also used for game hunting. During a period of one year, camera traps (n=16) were placed at a priori risk points for interspecies interactions: water (natural and artificial troughs), food placed on the ground for baiting wildlife, and pasture. To define indirect interspecies interactions, a critical time window for M. bovis to survive in the environment was selected based on the literature. Results suggest that wildlife frequented food and pasture points more often than water points, and that the number of visits increased through the dry season, peaking during the acorn season (October-January) and the deer breeding season (June-July). Direct interactions were rare (n=10), as opposed to indirect interactions (n=8992). Wildlife-followed-by-livestock interactions (n=7714) occurred much more often than livestock-followed-by-wildlife (n=1278) and were frequent at water points (66% water points, 17% food, 17% pasture). Results also suggest that water points are a hotspot for indirect interactions and might therefore be a source of infection at the wildlife-livestock interface in the territory covered, particularly for M. bovis, as it is around water where the bacteria seem to survive the longest. Preventing aggregation and therefore reducing contact rates between domestic and wild animals especially at water points may be valuable for disease control in South Central Spain.

  14. Watershed Governance in South-Central Texas: Working from the Bottom up

    NASA Astrophysics Data System (ADS)

    Lopes, V. L.

    2014-12-01

    The purpose of this presentation is to introduce a set of key concepts that can guide the development of ecological governance systems and briefly describe a watershed ecological governance project in south-central Texas. Ecological governance is a form of governance embedding ecological principles and values in all levels of decision making and action, from the personal to the global. The model of ecological governance discussed here incorporates ideas and approaches that are already being put into practice in many watershed governance projects in the US and abroad; it is based on the premise that contemporary governance systems will continue to evolve in this direction, incorporating more and more of the features of ecological governance. The watershed governance project described here was devised to ensure that the long-term ecological integrity of a small urbanazing waterhed in south-central Texas is preserved and that the water quality standards are maintained for present and future generations. The ecological integrity of small spring-fed watersheds in Texas are under serious threat due to rapid urban development dependent on groundwater supplies, continued drilling of personal wells that are exempt from pumping regulation, and lack of adequate legal jurisdiction for managing development in rural and semi-rural areas. The watershed governance project was motivated by a firm belief of local stakeholders that watershed protection is an individual as well as a community responsibility, and the recognition that a balance between growth and protection is essential to maintain watershed integrity. It is concluded that whereas emergent systems of ecological governance struggle to succeed in an institutional context oriented towards the pursuit of self-interest and competition, their acceptance will happen more readily as ecological principles and values diffuses throughout modern society.

  15. Digital Data from the Great Sand Dunes and Poncha Springs Aeromagnetic Surveys, South-Central Colorado

    USGS Publications Warehouse

    Drenth, B.J.; Grauch, V.J.S.; Bankey, Viki; New Sense Geophysics, Ltd.

    2009-01-01

    This report contains digital data, image files, and text files describing data formats and survey procedures for two high-resolution aeromagnetic surveys in south-central Colorado: one in the eastern San Luis Valley, Alamosa and Saguache Counties, and the other in the southern Upper Arkansas Valley, Chaffee County. In the San Luis Valley, the Great Sand Dunes survey covers a large part of Great Sand Dunes National Park and Preserve and extends south along the mountain front to the foot of Mount Blanca. In the Upper Arkansas Valley, the Poncha Springs survey covers the town of Poncha Springs and vicinity. The digital files include grids, images, and flight-line data. Several derivative products from these data are also presented as grids and images, including two grids of reduced-to-pole aeromagnetic data and data continued to a reference surface. Images are presented in various formats and are intended to be used as input to geographic information systems, standard graphics software, or map plotting packages.

  16. Multi-year GNSS monitoring of atmospheric IWV over Central and South America for climate studies

    NASA Astrophysics Data System (ADS)

    Bianchi, Clara Eugenia; Mendoza, Luciano Pedro Oscar; Fernández, Laura Isabel; Natali, María Paula; Meza, Amalia Margarita; Francisco Moirano, Juan

    2016-07-01

    Atmospheric water vapour has been acknowledged as an essential climate variable. Weather prediction and hazard assessment systems benefit from real-time observations, whereas long-term records contribute to climate studies. Nowadays, ground-based global navigation satellite system (GNSS) products have become widely employed, complementing satellite observations over the oceans. Although the past decade has seen a significant development of the GNSS infrastructure in Central and South America, its potential for atmospheric water vapour monitoring has not been fully exploited. With this in mind, we have performed a regional, 7-year-long and homogeneous analysis, comprising 136 GNSS tracking stations, obtaining high-rate and continuous observations of column-integrated water vapour and troposphere zenith total delay. As a preliminary application for this data set, we have estimated local water vapour trends, their significance, and their relation with specific climate regimes. We have found evidence of drying at temperate regions in South America, at a rate of about 2 % per decade, while a slow moistening of the troposphere over tropical regions is also weakly suggested by our results. Furthermore, we have assessed the regional performance of the empirical model GPT2w to blindly estimate troposphere delays. The model reproduces the observed mean delays fairly well, including their annual and semi-annual variations. Nevertheless, a long-term evaluation has shown systematical biases, up to 20 mm, probably inherited from the underlying atmospheric reanalysis. Additionally, the complete data set has been made openly available as supplementary material.

  17. Applications of SEASAT altimeter data in seismotectonic studies of the South-Central Pacific

    SciTech Connect

    Sailor, R.V.; Okal, E.A.

    1983-02-28

    Individual tracks of SEASAT altimeter data can be used effectively to identify significant bathymetric features in remote and unsurveyed ocean areas. It is especially important, for studies of oceanic seismicity, to identify correlation (or lack of correlation) between seismicity and bathymetric features. However, in many seismically active regions, bathymetric data are sparse or nonexistent. A typical example is the south-central Pacific, an area studied by Okal et al. (1980), who identified several sites of active intraplate seismicity. The purpose of the present paper is to demonstrate how SEASAT data can be used to aid in bathymetric and seismotectonic interpretation of this remote ocean area. We present two illustrations: (1) SEASAT observations of Macdonald seamount, a volcanically active seamount representing the youngest member in the Austral Island chain, and (2) SEASAT observation of a previously undiscovered fracture zone located at approximately 21.4 /sup 0/S and trending east-west between 232 /sup 0/E and 236 /sup 0/E. This fracture zone is located approximately 70 km to the south of a small region of active seismicity (96 events of magnitude greater than 2.7 from 1976 to 1980). On the basis of the demonstrated ability to observe active seamounts such as Macdonald and small fracture zones, we conclude that the observed seismicity in the region near 21 /sup 0/S, 233 /sup 0/E is due to intraplate stresses but is not associated with large-scale volcanism or with an active or fossil fracture zone.

  18. GPS Constraints on Strain Partitioning and Transfer in Alaska

    NASA Astrophysics Data System (ADS)

    Elliott, J.; Freymueller, J. T.; Larsen, C. F.

    2012-12-01

    GPS data from southern Alaska and eastern Canada have helped redraw the picture of how strain is partitioned and transferred within the region. Instead of a relatively simple boundary, the interactions of the Pacific plate and the Yakutat block with Alaska have created a complex margin made up of a number of small blocks and deformation zones. Relative motion is distributed along a variety of structures, including the Fairweather-Queen Charlotte, Denali, and Totschunda strike-slip fault systems. We present GPS data from across the region and use it to constrain a model for strain partitioning and transfer in southern and central Alaska and the adjacent region of Canada. In southeast Alaska, which contains the eastern boundary of the Yakutat block, the major tectonic feature is the dextral Fairweather-Queen Charlotte fault system. Most the relative plate motion is accommodated by 45 mm/yr of slip along this fault. Some of this motion may be transferred north along a fault connecting the Fairweather and Totschunda faults, but the majority is transferred west into the St. Elias orogen. The remaining relative plate motion in southeast Alaska is transferred east of the Fairweather-Queen Charlotte system, causing the region inboard of the Fairweather fault to undergo a clockwise rotation into the Northern Cordillera. About 2 mm/yr of relative motion is accommodated by dextral oblique motion along the Eastern Denali fault while 5% is transferred further east into the Northern Cordillera. Strain partitioning in south central Alaska, which contains the northern and western boundaries of the Yakutat block and the eastern end of the Aleutian megathrust, is more complicated. Most of the relative plate motion is accommodated along a narrow band of thrust faults within the St. Elias orogen. About 10-15% of the relative motion is transferred north of the St. Elias and causes the counterclockwise rotation of southern Alaska. Motion between this rotating block, the Northern

  19. Evaluating potential effects of an industrial road on winter habitat of caribou in North-Central Alaska

    USGS Publications Warehouse

    Wilson, Ryan R.; Gustine, David D.; Joly, Kyle

    2014-01-01

    Worldwide, some caribou (Rangifer tarandus) populations are experiencing declines due partially to the expansion of industrial development. Caribou can exhibit behavioral avoidance of development, leading to indirect habitat loss, even if the actual footprint is small. Thus, it is important to understand before construction begins how much habitat might be affected by proposed development. In northern Alaska, an industrial road that has been proposed to facilitate mining transects a portion of the Western Arctic caribou herd's winter range. To understand how winter habitat use might be affected by the road, we estimated resource selection patterns during winter for caribou in a study area surrounding the proposed road. We assessed the reductions of habitat value associated with three proposed routes at three distance thresholds for disturbance. High-value winter habitat tended to occur in locally rugged areas that have not burned recently and have a high density of lichen and early dates of spring snowmelt. We found that 1.5% to 8.5% (146-848 km2) of existing high-value winter habitat in our study area might be reduced in quality. The three alternative routes were only marginally different. Our results suggest that the road would have minimal direct effects on high-value winter habitat; however, additional cumulative impacts to caribou (e.g., increased access by recreationists and hunters) should be considered before the full effects of the road can be estimated.

  20. Transient rheology of the upper mantle beneath central Alaska inferred from the crustal velocity field following the 2002 Denali earthquake

    USGS Publications Warehouse

    Pollitz, F.F.

    2005-01-01

    The M7.9 2002 Denali earthquake, Alaska, is one of the largest strike-slip earthquakes ever recorded. The postseismic GPS velocity field around the 300-km-long rupture is characterized by very rapid horizontal velocity up to ???300 mm/yr for the first 0.1 years and slower but still elevated horizontal velocity up to ???100 mm/yr for the succeeding 1.5 years. I find that the spatial and temporal pattern of the displacement field may be explained by a transient mantle rheology. Representing the regional upper mantle as a Burghers body, I infer steady state and transient viscosities of ??1 = 2.8 ?? 1018 Pa s and ??2 = 1.0 ?? 1017 Pa s, respectively, corresponding to material relaxation times of 1.3 and 0.05 years. The lower crustal viscosity is poorly constrained by the considered horizontal velocity field, and the quoted mantle viscosities assume a steady state lower crust viscosity that is 7??1. Systematic bias in predicted versus observed velocity vectors with respect to a fixed North America during the first 3-6 months following the earthquake is reduced when all velocity vectors are referred to a fixed site. This suggests that the post-Denali GPS time series for the first 1.63 years are shaped by a combination of a common mode noise source during the first 3-6 months plus viscoelastic relaxation controlled by a transient mantle rheology.

  1. UNIT, ALASKA.

    ERIC Educational Resources Information Center

    Louisiana Arts and Science Center, Baton Rouge.

    THE UNIT DESCRIBED IN THIS BOOKLET DEALS WITH THE GEOGRAPHY OF ALASKA. THE UNIT IS PRESENTED IN OUTLINE FORM. THE FIRST SECTION DEALS PRINCIPALLY WITH THE PHYSICAL GEOGRAPHY OF ALASKA. DISCUSSED ARE (1) THE SIZE, (2) THE MAJOR LAND REGIONS, (3) THE MOUNTAINS, VOLCANOES, GLACIERS, AND RIVERS, (4) THE NATURAL RESOURCES, AND (5) THE CLIMATE. THE…

  2. Gravity investigations of the Chickasaw National Recreation Area, south-central Oklahoma

    USGS Publications Warehouse

    Scheirer, Daniel S.; Scheirer, Allegra Hosford

    2006-01-01

    The geological configuration of the Arbuckle Uplift in the vicinity of Chickasaw National Recreation Area in south-central Oklahoma plays a governing role in the distribution of fresh and mineral springs within the park and in the existence of artesian wells in and around the park. A confining layer of well-cemented conglomerate lies immediately below the surface of the recreation area, and groundwater migrates from an area of meteoric recharge where rocks of the Arbuckle-Simpson Aquifer crop out as close as two kilometers to the east of the park. Prominent, Pennsylvanian-aged faults are exposed in the aquifer outcrop, and two of the fault traces project beneath the conglomerate cover toward two groups of springs within the northern section of the park. We conducted gravity fieldwork and analysis to investigate the subsurface extensions of these major faults beneath Chickasaw National Recreation Area. By defining gravity signatures of the faults where they are exposed, we infer that the Sulphur and Mill Creek Faults bend to the south-west where they are buried. The South Sulphur Fault may project westward linearly if it juxtaposes rocks that have a density contrast opposite that of that fault's density configuration in the Sulphur Syncline area. The Sulphur Syncline, whose eastern extent is exposed in the outcrop area of the Arbuckle-Simpson Aquifer, does not appear to extend beneath Chickasaw National Recreation Area nor the adjacent City of Sulphur. The South Sulphur Fault dips steeply northward, and its normal sense of offset suggests that the Sulphur Syncline is part of a graben. The Mill Creek Fault dips vertically, and the Reagan Fault dips southward, consistent with its being mapped as a thrust fault. The Sulphur and Mill Creek Synclines may have formed as pull-apart basins in a left-lateral, left-stepping strike-slip environment. The character of the gravity field of Chickasaw National Recreation Area is different from the lineated gravity field in the area

  3. Estrogen pollution in a highly productive ecosystem off central-south Chile.

    PubMed

    Bertin, Angéline; Inostroza, Pedro A; Quiñones, Renato A

    2011-07-01

    While the presence of steroid estrogens in the environment has become a major environmental and health concern, their occurrence in coastal sediments remains poorly characterized. In this study, we measured the levels of three natural (estrone, 17β-estradiol, estriol) and one synthetic (17α-ethinylestradiol) estrogens in 54 coastal sediment samples collected from nine locations off central-southern Chile. Steroid estrogens were found in every sample. Remarkably high levels of 17α-ethinylestradiol were detected, reaching up to 48.14 ng/g dry weight. As a result, the global estrogenic loads were estimated to be high at all sites. Interestingly, they were found to correlate with the size of human populations served by sewage plants. Our study indicates that 17α-ethinylestradiol may accumulate in coastal sediments. The possible impact of this highly potent synthetic estrogen on the biota of the marine ecosystem off central-south Chile and on human health remains an open question.

  4. Miocene and Pliocene lacustrine and fluvial sequences, Upper Ramparts and Canyon village, Porcupine river, east-central Alaska

    USGS Publications Warehouse

    Fouch, T.D.; Carter, L.D.; Kunk, M.J.; Smith, C.A.S.; White, J.M.

    1994-01-01

    Cenozoic strata exposed along the Porcupine River between the Upper Ramparts and Canyon Village, Alaska, can be divided into five unconformity-bounded units (sequences) which are: lower and middle Miocene unit A, the white sandy fluvial sequence with peat beds; middle Miocene unit B, the basalt sequence-part B1 is basalt, and part B2 is organic-rich sedimentary beds; upper Miocene unit C, mudrock-dominated lake sequence; late Miocene or Pliocene to Pleistocene unit D, terrace gravels, detrital organic matter and associated sediments, and Holocene unit E, mixed sand and gravel-rich sediment and other sedimentary material including peat and eolian silt. The sequence (unit A) of lower and middle Miocene fluvial deposits formed in streams and on flood plains, just before the inception of local volanism. Fossil pollen from unit A suggests conifer-dominated regional forests and cool temperate climates. Peat beds and lake deposits from unit B contain pollen that indicates a warmer temperate climate coinciding with the middle Miocene thermal maximum. The lake deposits (unit C) downstream from the basalts accumulated in a small basin which resulted from a hydrologic system that was dammed in the late Miocene but breached soon thereafter. The lower part of the terrace gravels (unit D) expresses breaching of the dammed hydrologic system (of unit C). The Porcupine River became a major tributary of the Yukon River in late Pleistocene time when Laurentide ice blocked drainage from the Yukon interior basins causing meltwater to spill over the low divide separating it from the Porcupine River drainage initiating erosion and capture of the Yukon interior basins. ?? 1994.

  5. The deep structure of south-central Taiwan illuminated by seismic tomography and earthquake hypocenter data

    NASA Astrophysics Data System (ADS)

    Camanni, Giovanni; Alvarez-Marron, Joaquina; Brown, Dennis; Ayala, Concepcion; Wu, Yih-Min; Hsieh, Hsien-Hsiang

    2016-06-01

    The Taiwan mountain belt is generally thought to develop above a through-going basal thrust confined to within the sedimentary cover of the Eurasian continental margin. Surface geology, magnetotelluric, earthquake hypocenter, and seismic tomography data suggest, however, that crustal levels below this basal thrust are also currently being involved in the deformation. Here, we combine seismic tomography and earthquake hypocenter data to investigate the deformation that is taking place at depth beneath south-central Taiwan. In this paper, we define the basement as any pre-Eocene rifting rocks, and use a P-wave velocity of 5.2 km/s as a reference for the interface between these rocks and their sedimentary cover. We found that beneath the Coastal Plain and the Western Foothills clustering of hypocenters near the basement-cover interface suggests that this interface is acting as a detachment. This detachment is located below the basal thrust proposed from surface geology for this part of the mountain belt. Inherited basement faults appear to determine the geometry of this detachment, and their inversion in the Alishan area result in the development of a basement uplift and a lateral structure in the thrust system above them. However, across the Shuilikeng and the Chaochou faults, earthquake hypocenters define steeply dipping clusters that extend to greater than 20 km depth, above which higher velocity basement rocks are uplifted beneath the Hsuehshan and Central ranges. We interpret these clusters to form a deeply penetrating, east-dipping ramp that joins westward with the detachment at the basement-cover interface. It is not possible to define a basal thrust to the east, beneath the Central Range.

  6. Prevalence of Pulmonary Tuberculosis among Prison Inmates at Mbarara Central Prison, South Western Uganda

    PubMed Central

    Owokuhaisa, Judith; Thokerunga, Eric; Bazira, Joel

    2015-01-01

    Aims This study was conducted to determine the prevalence of tuberculosis among prison inmates at Mbarara Central prison Design A cross sectional study was carried out at Mbarara Central Prison in Mbarara district, Kiswahili cell in Mbarara municipality among female and male prison in mates between June 2012 to August 2012. A questionnaire was administered to each prison inmate who consented in writing and two sputum specimens were collected and examined by Ziehl-Neelsen technique. Results At the time of the study, the prison had 900 inmates (both males and females). A total of 648 in mates were screened and 248 inmates enrolled in the study. Of the 248 inmates, 5 inmates were new cases of TB while 29 inmates were already on TB treatment. The median age of participants was 28 years (23.5-33 IQR) and 96.4% were males with majority (22.6%) coming from Mbarara as a home district. The participants had stayed in prison for a median duration of 2 years (1-3 IQR) and 23.7% had ever been in prison before. The median number of inmates per cell was 140 (138-149 IQR) and inmates (female and male) had a body mass index of 21.4 (19.9-22.6 IQR) and 20.2 (19.2-26.7 IQR) respectively. Of the inmates evaluated, 68.8% reported cough for 2 or more weeks. Other symptoms reported were weight loss (in 40.7%) and night sweats (in 35.8%). Of the 248 inmates evaluated, 95 inmates were tested for HIV and 4.1% were HIV serology positive. Conclusion The prevalence of TB in Mbarara Central prison South Western Uganda is low but calls for continued surveillance through regular TB screening. PMID:26949722

  7. A seismological study of the 1835 seismic gap in south-central Chile

    NASA Astrophysics Data System (ADS)

    Campos, J.; Hatzfeld, D.; Madariaga, R.; Lopez, G.; Kausel, E.; Zollo, A.; Iannacone, G.; Fromm, R.; Barrientos, S.; Lyon-Caen, H.

    2002-09-01

    We study the possible seismic gap in the Concepción-Constitución region of south-central Chile and the nature of the M=7.8 earthquake of January 1939. From 1 March to 31 May 1996 a seismic network of 26 short period digital instruments was deployed in this area. We located 379 hypocenters with rms travel time residuals of less than 0.50 s using an approximate velocity distribution. Using the VELEST program, we improved the velocity model and located 240 high precision hypocenters with residuals less than 0.2 s. The large majority of earthquakes occurred along the Wadati-Benioff zone along the upper part of the downgoing slab under central Chile. A few shallow events were recorded near the chain of active volcanos on the Andes; these events are similar to those of Las Melozas near Santiago. A few events took place at the boundary between the coastal ranges and the central valley. Well constrained fault plane solutions could be computed for 32 of the 240 well located events. Most of the earthquakes located on the Wadati-Benioff zone had "slab-pull" fault mechanism due to tensional stresses sub-parallel to the downgoing slab. This "slab-pull" mechanism is the same as that of eight earthquakes of magnitude around 6 that are listed in the CMT catalog of Harvard University for the period 1980-1998. This is also the mechanism inferred for the large 1939 Chilean earthquake. A very small number of events in the Benioff zone had "slab-push" mechanisms, that is events whose pressure axis is aligned with the slab. These events are found in double layered Wadati-Benioff zones, such as in northern Chile or Japan. Our spatial resolution is not good enough to detect the presence of a double layer, but we suspect there may be one.

  8. Developing a chironomid training set for western South America (South-Central Chile): potential for quantitative temperature reconstructions

    NASA Astrophysics Data System (ADS)

    Araneda, A.; Larocque-Tobler, I.; Torrejon, F.; Grosjean, M.; Jana-Pinninghoff, P.; Ortega, C.; Urrutia, R.

    2012-12-01

    Quantitative climate reconstructions of the last two millennia are a fundamental issue in order to compare the current trends in climate observed nowadays. At global scale most of the climate reconstructions have been developed for the Northern Hemisphere, while for the Southern Hemisphere quantitative reconstructions are very rare and very limited geographically. The recognition of such disparity has generated among other research initiatives the LOTRED-SA Long-Term climate Reconstruction and Dynamics of (southern) South America, a collaborative, high-resolution multi-proxy approach within the framework of the IGBP-PAGES program. In this context our work presents the results of a 50-lakes training set in Central-Southern Chile developed with the aim to generate a basis for quantitative chironomid-inferred temperature reconstructions for this part of the continent. Chironomids (Insecta: Diptera) are aquatic insects that develop a great proportion of their life cycle as larvae in aquatic ecosystems. Several studies, developed mainly in the Northern Hemisphere, have proven their usefulness in reconstructing past climate due to the larvae's relationship to temperature. The training set developed here includes lakes located between 34 and 48 S, covering a broad temperature (as latitudinal) gradient. The surface (0-1 cm) sediment of each lake was sampled and chironomids, organic matter and nutrient were analyzed. Water analyses included the measurement of 10 variables (AirT, WBT, WST, N-tot, P-tot, Fe, Na, pH among others). In order to identify the most important variables explaining the highest variance in the chironomid assemblages, ordinations analyses were performed. A preliminary DCA analysis indicated, according to the length of gradients smaller than 3 STD, that a linear model was more appropriate for further analysis. Hence a RDA analysis was applied to the environmental and species data, indicating that the most important variables to determine chironomid

  9. South Central Kansas Gender Equity Project. 1994-95 Annual Report, Field Trip Guide, and Library Resource Catalog.

    ERIC Educational Resources Information Center

    Dodson-Pennington, Laura S.; And Others

    Cowley County Community College established the South Central Kansas Gender Equity Educational Resource Center in 1991-92 to facilitate career awareness, exploration, and preparation by students of all ages, focusing on opportunities in non-traditional fields for both females and males. This document presents an annual report for the Center for…

  10. A COMPARISON OF INTER-ANALYST DIFFERENCES IN THE CLASSIFICATION OF A LANDSAT TEM+ SCENE IN SOUTH-CENTRAL VIRGINIA

    EPA Science Inventory

    This study examined inter-analyst classification variability based on training site signature selection only for six classifications from a 10 km2 Landsat ETM+ image centered over a highly heterogeneous area in south-central Virginia. Six analysts classified the image...

  11. The Out-of-State Placement of Children: South Central State Profiles. Major Issues in Juvenile Justice Information and Training.

    ERIC Educational Resources Information Center

    Hall, John C.; And Others

    This document, 1 in a series of 10, presents state profiles of the results of a systematic examination of child care agencies and their involvement with out-of-state residential care for children. This volume contains profiles of the South Central states of Arkansas, Colorado, Kansas, Louisiana, Mississippi, Missouri, New Mexico, Oklahoma, and…

  12. The Wallula fault and tectonic framework of south-central Washington, as interpreted from magnetic and gravity anomalies

    SciTech Connect

    Blakely, Richard J.; Sherrod, Brian; Weaver, Craig; Wells, Ray E.; Rohay, Alan C.

    2013-11-13

    Magnetic and gravity data, collected in south-central Washington near the Yakima Fold and Thrust Belt (YFTB) are used to model upper crustal structure, the extent of the late Columbia River Basalt flow named the Ice Harbor member, the vertical conduits (dikes) that the Ice Harbor erupted from, and whether the dikes are offset or affected by faulting on the Wallula Fault zone.

  13. Dancing between Two Worlds: A Portrait of the Life of a Black Male Teacher in South Central LA

    ERIC Educational Resources Information Center

    Lynn, Marvin

    2006-01-01

    This article offers a portrait of a young black male teacher in an urban school in South Central Los Angeles. In the portrait, the words of the subject are intertwined with the thoughts and reactions of the researcher as a way in which to capture his life history narrative and offer his reading of the world. The article discusses the participant's…

  14. A Comparative Overview of the Education of Deaf Children in Central America, the Caribbean and Parts of South America.

    ERIC Educational Resources Information Center

    Delgado, Gilbert L.

    This paper describes the current state of education for deaf children in Central America and the Caribbean (with some mention of parts of South America), focusing on an historical description of events and forces impacting these regions; current educational philosophies; adult associations of deaf people; intra/intercountry networking; educational…

  15. Immigration and the Challenge of Education: A Social Drama Analysis in South Central Los Angeles. Education, Politics and Public Life

    ERIC Educational Resources Information Center

    Jaramillo, Nathalia E.

    2012-01-01

    Part enthnograpy and part testimony, this book analyzes a school setting and community from the standpoint of a group of immigrant mothers (las madres) in South Central Los Angeles who were concerned about the education of their children and the violence in their communities. Written in both the first and third person, in Spanish and English, the…

  16. Transition from the Farallon Plate subduction to the collision between South and Central America: Geological evolution of the Panama Isthmus

    NASA Astrophysics Data System (ADS)

    Barat, Flore; Mercier de Lépinay, Bernard; Sosson, Marc; Müller, Carla; Baumgartner, Peter O.; Baumgartner-Mora, Claudia

    2014-05-01

    This paper presents new geological constraints on the collision of southern Central America with South America, and the resulting deformational episodes that have affected the Panama Isthmus since the Late Cretaceous. The Panama Isthmus is located in southwestern Central America, and it represents the zone of contact between the two land masses: Central America and South America. This collision event is still active today. It has resulted in regional uplift since the Late Miocene/Pliocene and is responsible for the Great American Biotic Interchange between South and North America. Depending on the methods of investigation used, and due to the lack of data available, the time when this collision began is still widely debated and poorly constrained. To better constrain this age, we have studied the rock formations and the tectonic deformations in central and eastern Panama that have occurred since the Late Cretaceous. This study presents new rock ages, field-work documentation and analyses, and seismic-line interpretations, and it is complemented by spatial images for the eastern Panama area. During the Middle Eocene, a number of changes suddenly appeared in the geological records that were synchronous with the break-up of southern Central America into two smaller blocks: Chorotega and Chocó. Our main results identify the prevalence of an extensional tectonic regime from the Middle Eocene to the Middle Miocene that caused the formation of horst and graben structures with thick sedimentary basin fills, and a synchronous clockwise block rotation. Here, we propose that these geologic events are associated with the initiation of the oblique collision of southern Central America with South America. The first contact of the southeastern extremity of Central America occurred around 40 Ma to 38 Ma, and then propagated northwestwards. We describe here this long-term collision episode in relation to the history of the Panama Isthmus.

  17. Sedimentology and Sequence Stratigraphy of the Lower Cretaceous Fortress Mountain and Torok Formations Exposed Along the Siksikpuk River, North-Central Alaska

    USGS Publications Warehouse

    Houseknecht, David W.; Schenk, Christopher J.; Wartes, Marwan A.

    2007-01-01

    An exposure of the Lower Cretaceous Fortress Mountain and Torok Formations along the Siksikpuk River in north-central Alaska provides a rare opportunity to observe the stratigraphic contact between these two formations and to interpret the depositional facies and sequence stratigraphy of the exposed strata. The Fortress Mountain Formation at the base of the measured section includes braided-fluvial and coastal-plain facies deposited in a lowstand-systems tract, and an overlying succession of mostly shallow marine facies deposited in the basal part of a transgressive-systems tract. The overlying Torok Formation includes a thick, upward-deepening succession of marine-shelf to marine-slope facies deposited in the upper part of the transgressive-systems tract. The upper part of the section includes marine-slope and incised-slope-channel turbidite deposits of the Torok Formation, interpreted as a highstand-systems tract. Consideration of the balance between accommodation and sediment flux inferred from the sequence-stratigraphic analysis suggests that both tectonics and eustasy may have influenced deposition of the lowstand-systems and transgressive-systems tracts. In contrast, the highstand-systems tract may have been primarily influenced by progradation of a regional sediment-dispersal system and by subsidence induced by sediment loading.

  18. Extending airborne electromagnetic surveys for regional active layer and permafrost mapping with remote sensing and ancillary data, Yukon Flats ecoregion, central Alaska

    USGS Publications Warehouse

    Pastick, Neal J.; Jorgenson, M. Torre; Wylie, Bruce K.; Minsley, Burke J.; Ji, Lei; Walvoord, Michelle A.; Smith, Bruce D.; Abraham, Jared D.; Rose, Joshua R.

    2013-01-01

    Machine-learning regression tree models were used to extrapolate airborne electromagnetic resistivity data collected along flight lines in the Yukon Flats Ecoregion, central Alaska, for regional mapping of permafrost. This method of extrapolation (r = 0.86) used subsurface resistivity, Landsat Thematic Mapper (TM) at-sensor reflectance, thermal, TM-derived spectral indices, digital elevation models and other relevant spatial data to estimate near-surface (0–2.6-m depth) resistivity at 30-m resolution. A piecewise regression model (r = 0.82) and a presence/absence decision tree classification (accuracy of 87%) were used to estimate active-layer thickness (ALT) (< 101 cm) and the probability of near-surface (up to 123-cm depth) permafrost occurrence from field data, modelled near-surface (0–2.6 m) resistivity, and other relevant remote sensing and map data. At site scale, the predicted ALTs were similar to those previously observed for different vegetation types. At the landscape scale, the predicted ALTs tended to be thinner on higher-elevation loess deposits than on low-lying alluvial and sand sheet deposits of the Yukon Flats. The ALT and permafrost maps provide a baseline for future permafrost monitoring, serve as inputs for modelling hydrological and carbon cycles at local to regional scales, and offer insight into the ALT response to fire and thaw processes.

  19. Evolution of the snow area index of the subarctic snowpack in central Alaska over a whole season. consequences for the air to snow transfer of pollutants.

    PubMed

    Taillandier, A S; Domine, F; Simpson, W R; Sturm, M; Douglas, T A; Severin, K

    2006-12-15

    The detailed physical characteristics of the subarctic snowpack must be known to quantify the exchange of adsorbed pollutants between the atmosphere and the snow cover. For the first time, the combined evolutions of specific surface area (SSA), snow stratigraphy, temperature, and density were monitored throughout winter in central Alaska. We define the snow area index (SAI) as the vertically integrated surface area of snow crystals, and this variable is used to quantify pollutants' adsorption. Intense metamorphism generated by strong temperature gradients formed a thick depth hoar layer with low SSA (90 cm(2) g-1) and density (200 kg m(-3)), resulting in a low SAI. After snowpack buildup in autumn, the winter SAI remained around 1000 m(2)/m(2) of ground, much lower than the SAI of the Arctic snowpack, 2500 m(2) m-(2). With the example of PCBs 28 and 180, we calculate that the subarctic snowpack is a smaller reservoir of adsorbed pollutants than the Arctic snowpack and less efficiently transfers adsorbed pollutants from the atmosphere to ecosystems. The difference is greater for the more volatile PCB 28. With climate change, snowpack structure will be modified, and the snowpack's ability to transfer adsorbed pollutants from the atmosphere to ecosystems may be reduced, especially for the more volatile pollutants.

  20. Northwest coast of United States to Central South America at Night

    NASA Video Gallery

    This video was taken on August 19, 2011 from 08:56:00 to 09:22:18 GMT from the ISS. This pass begins just southeast of Alaska, and the first cities that the ISS passes over (seen approximately 10 s...

  1. 3. Northwest coast of United States to Central South America at Night

    NASA Video Gallery

    This video was taken on August 19, 2011 from 08:56:00 to 09:22:18 GMT from the ISS. This pass begins just southeast of Alaska, and the first cities that the ISS passes over (seen approximately 10 s...

  2. Effects of the earthquake of March 27, 1964, at Whittier, Alaska: Chapter B in The Alaska earthquake, March 27, 1964: effects on communities

    USGS Publications Warehouse

    Kachadoorian, Reuben

    1965-01-01

    Whittier, Alaska, lying at the western end of Passage Canal, is an ocean terminal of The Alaska Railroad. The earthquake that shook south-central Alaska at 5:36 p.m. (Alaska Standard Time) on March 27, 1964, took the lives of 13 persons and caused more than $5 million worth of damage to Government and private property at Whittier. Seismic motion lasted only 2½-3 minutes, but when it stopped the Whittier waterfront was in shambles land the port facilities were inoperable. Damage was caused by (1) a 5.3-foot subsidence of the landmass, sufficient to put some of the developed land under water during high tides, (2) seismic shock, (3) fracturing of fill and unconsolidated sediments, (4) compaction of fill and unconsolidated deposits, (5) submarine landslides which generated waves that destroyed part of The Alaska Railroad roadbed and other property, (6) at least two, but probably three, waves generated by landslides, which completely wrecked the buildings of two lumber companies, the stub pier, the small-boat harbor, the car-barge slip dock, and several homes, and (7) fire that destroyed the fuel-storage tanks at the Whittier waterfront. Many buildings and other facilities were totally wrecked, others were damaged to lesser degrees. For example, the 14-story reinforced concrete Hodge Building, which rests upon at least 44 feet of sandy gravel, was moderately damaged by seismic shock, but the six-story reinforced-concrete Buckner Building, which rests upon bedrock, was only slightly damaged.

  3. Vitrinite reflectance data for Cretaceous marine shales and coals in the Bighorn Basin, north-central Wyoming and south-central Montana

    USGS Publications Warehouse

    Pawlewicz, Mark J.; Finn, Thomas M.

    2012-01-01

    The Bighorn Basin is a large Laramide (Late Cretaceous through Eocene) structural and sedimentary basin that encompasses about 10,400 square miles in north-central Wyoming and south-central Montana. The purpose of this report is to present new vitrinite reflectance data collected from Cretaceous marine shales and coals in the Bighorn Basin to better characterize the thermal maturity and petroleum potential of these rocks. Ninety-eight samples from Lower Cretaceous and lowermost Upper Cretaceous strata were collected from well cuttings from wells stored at the U.S. Geological Survey (USGS) Core Research Center in Lakewood, Colorado.

  4. Risk for transfusion-transmitted infectious diseases in Central and South America.

    PubMed Central

    Schmunis, G. A.; Zicker, F.; Pinheiro, F.; Brandling-Bennett, D.

    1998-01-01

    We report the potential risk for an infectious disease through tainted transfusion in 10 countries of South and Central America in 1993 and in two countries of South America in 1994, as well as the cost of reagents as partial estimation of screening costs. Of the 12 countries included in the study, nine screened all donors for HIV; three screened all donors for hepatitis B virus (HBV); two screened all donors for Trypanosoma cruzi; none screened all donors for hepatitis C virus (HCV); and six screened some donors for syphilis. Estimates of the risk of acquiring HIV through blood transfusion were much lower than for acquiring HBV, HCV, or T. cruzi because of significantly higher screening and lower prevalence.rates for HIV. An index of infectious disease spread through blood transfusion was calculated for each country. The highest value was obtained for Bolivia (233 infections per 10,000 transfusions); in five other countries, it was 68 to 103 infections per 10,000. The risks were lower in Honduras (nine per 10,000), Ecuador (16 per 10,000), and Paraguay (19 per 10,000). While the real number of potentially infected units or infected persons is probably lower than our estimates because of false positives and already infected recipients, the data reinforce the need for an information system to assess the level of screening for infectious diseases in the blood supply. Since this information was collected, Chile, Colombia, Costa Rica, and Venezuela have made HCV screening mandatory; serologic testing for HCV has increased in those countries, as well as in El Salvador and Honduras. T. cruzi screening is now mandatory in Colombia, and the percentage of screened donors increased not only in Colombia, but also in Ecuador, El Salvador, and Paraguay. Laws to regulate blood transfusion practices have been enacted in Bolivia, Guatemala, and Peru. However, donor screening still needs to improve for one or more diseases in most countries. PMID:9452393

  5. 3D Anisotropic structure of the south-central Mongolia from Rayleigh and Love wave tomography

    NASA Astrophysics Data System (ADS)

    Yu, D.; Wu, Q.; Montagner, J. P.

    2014-12-01

    A better understanding of the geodynamics of the crust and mantle below Baikal-Mongolia is required to identify the role of mantle processes versus that of far-field tectonic effects from India-Asia collision. Anisotropy tomography can provide new perspective to the continental growth mechanism. In order to study the 3D anisotropic structure of the upper mantle in the south-central Mongolia, we collected the vertical and transverse components of seismograms recorded at 69 broadband seismic stations. We have measured inter-station phase velocities of 7181 Rayleigh waves and 901 Love waves using the frequency-time analysis of wavelet transformation method for the fundamental mode at period range 10~80s. The lateral phase velocity variations are computed by using a regionalization method. These phase velocities have been inverted to obtain the first anisotropic model including Sv velocities, azimuthal and radial anisotropy. The Middle Gobi is associated with low velocity. Based on the distribution of the Cenozoic basalts in the Middle Gobi, it refers that the low velocity anomaly is related to the Cenozoic volcanism. In the northern domain, near to Baikal zone, the azimuthal anisotropy is normal to the Baikal rift and consistent with the fast direction of previous SKS splitting measurements. In the South Gobi, north to Main Mongolian Lineament, the azimuthal anisotropy is NEE-SWW in the crust and NW-SE in the mantle. It indicates that the crust and mantle are decoupled. We propose that the crustal deformation is related to the far-field effects of India-Asia collision and that the mantle flow is correlated with the Baikal rift activity. Further study in process will provide more evidence and insight to better understand the geodynamics in this region.

  6. Risk for transfusion-transmitted infectious diseases in Central and South America.

    PubMed

    Schmunis, G A; Zicker, F; Pinheiro, F; Brandling-Bennett, D

    1998-01-01

    We report the potential risk for an infectious disease through tainted transfusion in 10 countries of South and Central America in 1993 and in two countries of South America in 1994, as well as the cost of reagents as partial estimation of screening costs. Of the 12 countries included in the study, nine screened all donors for HIV; three screened all donors for hepatitis B virus (HBV); two screened all donors for Trypanosoma cruzi; none screened all donors for hepatitis C virus (HCV); and six screened some donors for syphilis. Estimates of the risk of acquiring HIV through blood transfusion were much lower than for acquiring HBV, HCV, or T. cruzi because of significantly higher screening and lower prevalence.rates for HIV. An index of infectious disease spread through blood transfusion was calculated for each country. The highest value was obtained for Bolivia (233 infections per 10,000 transfusions); in five other countries, it was 68 to 103 infections per 10,000. The risks were lower in Honduras (nine per 10,000), Ecuador (16 per 10,000), and Paraguay (19 per 10,000). While the real number of potentially infected units or infected persons is probably lower than our estimates because of false positives and already infected recipients, the data reinforce the need for an information system to assess the level of screening for infectious diseases in the blood supply. Since this information was collected, Chile, Colombia, Costa Rica, and Venezuela have made HCV screening mandatory; serologic testing for HCV has increased in those countries, as well as in El Salvador and Honduras. T. cruzi screening is now mandatory in Colombia, and the percentage of screened donors increased not only in Colombia, but also in Ecuador, El Salvador, and Paraguay. Laws to regulate blood transfusion practices have been enacted in Bolivia, Guatemala, and Peru. However, donor screening still needs to improve for one or more diseases in most countries.

  7. Biomarker evidence for increasing aridity in south-central India over the Holocene

    NASA Astrophysics Data System (ADS)

    Sarkar, S.; Wilkes, H.; Prasad, S.; Brauer, A.; Basavaiah, N.; Strecker, M. R.; Sachse, D.

    2012-12-01

    Summer monsoonal rainfall has played an important role in the development and sustenance of the largely agro-based economy in the Indian subcontinent in the recent past. A better understanding of past variations in monsoonal rainfall can therefore lead to an assessment of its potential impact on early human societies. However, our knowledge of spatiotemporal patterns of past monsoon strength, as inferred from proxy records, is limited due to the lack of high-resolution paleo-hydrological records from continental archives. Here, we reconstruct centennial-scale hydrological variability associated with changes in the intensity of the Indian Summer Monsoon based on a record of lipid biomarker abundances and compound-specific stable isotopic composition of a 10-m-long sediment core from saline-alkaline Lonar Lake, situated in the core 'monsoon zone' of south-central India. We identified three periods of distinct hydrology over the Holocene in south-central India. The period between 10.4 and 6.5 ka BP was characterized by a relatively high abundance of land-plant biomarkers, such as long-chain n-alkanes. The composition of these leaf-wax n-alkanes (weighted average of concentration of different chain-length n-alkanes, expressed as the ACL index) and their negative δ13C (-30‰ to -33 ‰) indicate the dominance of woody C3 vegetation in the catchment, and negative δD (-170‰ to -175‰) values argue for a wet period due to an intensified monsoon. Rapid fluctuations in abundance of both terrestrial and aquatic biomarkers between 6.5 and 4 ka BP indicate an unstable lake ecosystem, culminating in a transition to arid conditions. Higher ACL values and a pronounced shift to more positive δ13C values (up to -22‰) of leaf-wax n-alkanes over this period indicate a change of dominant vegetation to C4 grasses. Along with a 40‰ increase in leaf wax n-alkane δD values, which likely resulted from less rainfall and/or higher plant evapotranspiration, we interpret this period

  8. Late Quaternary vegetation history of Rough Canyon, south-central New Mexico, USA

    USGS Publications Warehouse

    Betancourt, J.L.; Aasen, Rylander K.; Penalba, C.; McVickar, J.L.

    2001-01-01

    South-central New Mexico, USA, at the junction of the Rocky Mountains, High Plains and Chihuahuan Desert, is one of the better known regions in the late Quaternary of North America. Plant macrofossils and pollen from a packrat midden series in Rough Canyon, New Mexico allows refinement of plant distributions and paleoclimates in this transitional area since full glacial times. From 17000 to 12000 14C yr BP, Pinus edulis-Juniperus scopulorum woodlands dominated limestone substrates between 1800 and 1490 m, with Pseudotsuga menziesii and other mixed-conifer species restricted to shady, north-facing slopes. Juniperus deppeana, the dominant juniper today above 2000 m in southern New Mexico, is conspicuously absent from glacial middens and must have been displaced south of the US-Mexico border. The minimum climatic conditions for P. edulis-J. scopulorum woodlands are ca 20% wetter and 3.5-5??C cooler (July mean maximum temperatures) than the modern climate at Rough Canyon. Holocene warming/drying may have started as early as 12000 14C yr BP with the extirpation of J. scopulorum from Rough Canyon, and was completed by at least 10540 14C yr BP. The record for arrivals of some desert species is confounded by traces of pollen and macrofossils in some of the glacial middens, which could signify either earliest occurrence or temporal mixing (contamination) of assemblages. AMS 14C dating can discriminate between early arrival and contamination in midden macrofossils but not in pollen. AMS dates show that Choisya dumosa, presently near its northern (cold) limits at Rough Canyon, endured late glacial winters, possibly as clonal populations. Some Larrea tridentata leaves and pollen occur in middens dominated by conifers and oaks no longer at the site; an AMS date of 3205 14C yr BP on Larrea leaves from one midden indicates contamination. Evidence for some macrofossil contamination, however, does not rule out the possibility that pollen of desert elements (e.g. Larrea, Prosopis

  9. Tephrochronology of rare Plio-Pleistocene fossiferous strata in south-central Afar, Ethiopia

    NASA Astrophysics Data System (ADS)

    DiMaggio, E.; Arrowsmith, R.; Campisano, C. J.; Deino, A. L.

    2013-12-01

    Sedimentary basins in the south and central Afar Depression archive the complex structural, climatic, volcanic, and biologic development of the region during the Pliocene and Pleistocene. The lower Awash Valley in central Afar has long served as a focus for these investigations, including the extensive work conducted to place fossil assemblages (including hominins) into stratigraphic and temporal context. Here we present a detailed analysis of tephra chemistry, correlations, and ages of the newly mapped and fossiliferous area of eastern Ledi-Geraru (ELG) in the lower Awash Valley (~3-2.5 Ma). Our results allow us to construct a tephrostratigraphic framework that provides important constraints for regional studies previously lacking a calibrated sedimentary record spanning 3 to 2.7 Ma. Based on glass chemistry and morphology, 40Ar/39Ar dating of feldspars, and stratigraphic mapping, we identified 23 distinct tephras (8 of which were dated) in >100 m of newly mapped fluvial and lacustrine sediments at ELG. The oldest tuff at ELG (Kuhulta Tuff; 2.994 Ma) is exposed in lake sediments (diatomite) that lie 3-5 m above basalt flows dated to ca. 3 Ma. The youngest ELG tephra (ca. 2.44 Ma) outcrops as a lenticular channel tuff in sediments faulted against older strata (~2.7 Ma). Between these two tephras lies the Gurumaha Tuff (ca. 2.82 Ma) and the Daáma and Bulinan Tuffs (both ca. 2.85 Ma), which provide excellent stratigraphic ties across a distance of 7.5 km, allowing us to document a lateral facies change from lacustrine in northern ELG to more nearshore in the south. These tuffs also confirm the presence of a fossiferous sedimentary record spanning the late Pliocene sedimentary gap in lower Awash Valley stratigraphy (ca. 2.94 - 2.7 Ma). While the youngest and oldest tephras at ELG temporally overlap with dated tephras from the well-described Hadar (3.8 - 2.94 Ma) and Busidima (2.7 - 0.016 Ma) Formations, we have yet to confirm geochemical correlates to any tephra

  10. How Socio-Economic Conditions Influence Forest Policy Development in Central and South-East Europe

    NASA Astrophysics Data System (ADS)

    Vuletić, Dijana; Potočić, Nenad; Krajter, Silvija; Seletković, Ivan; Fürst, Christine; Makeschin, Franz; Galić, Zoran; Lorz, Carsten; Matijašič, Dragan; Zupanič, Matjaž; Simončič, Primož; Vacik, Harald

    2010-12-01

    In this article, several findings on socio-economic conditions derived from national reports and a web-based questionnaire are discussed and related to the changing role of forestry and the future forest policy development. A number of Central and South-eastern European countries taking part in a SEE-ERA-NET project ReForMan project ( www.reforman.de ) participated in data acquisition: Austria, Bosnia and Herzegovina, Croatia, Germany, Serbia and Slovenia. The aim of the research was to illustrate the present structure of forestry sector, as well as investigate newly emerging topics in forestry of Central and South-eastern Europe. The results indicated certain patterns in attitudes and perceptions among stakeholders that can be related to socio-economic conditions defined for each country. Clear differences between member and non-member countries exist only in level of implementation of EU legislation. Results showed consensus on main threats to the forests among all countries, but also some country specifics in perceptions of factors influencing forestry, their importance and professional competencies. These results could be additionally explained by influence of historical conditions which shaped development of forest sector in SEE region especially in its organizational dimension as well as in perceived role of forestry expressed through recognition of main forest functions. The influence of European forest policy processes in the region is evident through adaptation of EU legislation and perceived implications of international processes on national levels. Based on this observation, two possible options for future development of the forestry sector can be foreseen: (i) focusing on the productive function of forests and fostering its' sustainable use; or (ii) putting an emphasis on environmental and social issues. In both cases supporting public

  11. Geostatistical applications in ground-water modeling in south-central Kansas

    USGS Publications Warehouse

    Ma, T.-S.; Sophocleous, M.; Yu, Y.-S.

    1999-01-01

    This paper emphasizes the supportive role of geostatistics in applying ground-water models. Field data of 1994 ground-water level, bedrock, and saltwater-freshwater interface elevations in south-central Kansas were collected and analyzed using the geostatistical approach. Ordinary kriging was adopted to estimate initial conditions for ground-water levels and topography of the Permian bedrock at the nodes of a finite difference grid used in a three-dimensional numerical model. Cokriging was used to estimate initial conditions for the saltwater-freshwater interface. An assessment of uncertainties in the estimated data is presented. The kriged and cokriged estimation variances were analyzed to evaluate the adequacy of data employed in the modeling. Although water levels and bedrock elevations are well described by spherical semivariogram models, additional data are required for better cokriging estimation of the interface data. The geostatistically analyzed data were employed in a numerical model of the Siefkes site in the project area. Results indicate that the computed chloride concentrations and ground-water drawdowns reproduced the observed data satisfactorily.This paper emphasizes the supportive role of geostatistics in applying ground-water models. Field data of 1994 ground-water level, bedrock, and saltwater-freshwater interface elevations in south-central Kansas were collected and analyzed using the geostatistical approach. Ordinary kriging was adopted to estimate initial conditions for ground-water levels and topography of the Permian bedrock at the nodes of a finite difference grid used in a three-dimensional numerical model. Cokriging was used to estimate initial conditions for the saltwater-freshwater interface. An assessment of uncertainties in the estimated data is presented. The kriged and cokriged estimation variances were analyzed to evaluate the adequacy of data employed in the modeling. Although water levels and bedrock elevations are well described

  12. Geomorphology and sedimentology of hummocky terrain, south-central Alberta, Canada

    NASA Astrophysics Data System (ADS)

    Munro-Stasiuk, Mandy J.

    The landscape in south-central Alberta, Canada, is dominated by a suite of landforms that formed beneath the Laurentide Ice Sheet. This thesis explores the origins of those landforms, specifically hummocky terrain. Sediments in the hummocks, hummock form, and associations with other landforms are examined to determine hummock genesis. Sediment was examined from over one hundred exposures through the "Buffalo Lake Moraine" at Travers Reservoir, McGregor Reservoir, and the Little Bow River. This belt of hummocky terrain (like most hummocky terrain regions) is traditionally interpreted as forming at, or near, the stagnating margins of the Laurentide Ice Sheet by supraglacial letdown. However, hummocks in south-central Alberta contain a complex variety of sediments and materials atypical of supraglacial letdown: in situ bedrock, thrust bedrock, lodgement till, melt-out till, sorted sand and gravel, rippled sand, rhythmically-bedded sand, silt, and clay, and pervasively sheared beds. All sediment types and deformation structures were deposited, or formed, subglacially. Also, the deposits make up in situ stratigraphies that record the history of initial Laurentide Ice Sheet advance into the area (lodgment till and thrust bedrock), the extensive accumulation of water at the bed (glaciolacustrine beds), and ice stagnation (melt-out till). Regardless of the genesis of sediments in hummocks, sedimentary units and structures are abruptly truncated by the surface that represents the hummock and trough morphology, demonstrating that the hummocks are erosional forms and that they represent a landscape unconformity. Subglacial sediments predating the erosion and subglacial eskers overlying the erosion surface strongly suggest that hummock erosion was subglacial. Also, hummock morphology, lithostratigraphy correlated from hummock to hummock, abrupt truncation at the land surface, and widespread boulder lags support meltwater erosion for hummocky terrain in the region. Well

  13. Recurrent giant earthquakes in South-Central Chile revealed by lacustrine sedimentary records

    NASA Astrophysics Data System (ADS)

    Moernaut, J.; de Batist, M. A.; Heirman, K.; van Daele, M.; Brümmer, R.; Pino, M.; Urrutia, R.; Wolff, C.; Brauer, A.; Roberts, S.; Kilian, R.

    2009-12-01

    Megathrust (‘giant’) earthquakes in the South-Central Chilean subduction zone (e.g. 1960 earthquake; Mw: 9.5) cause landslides, tsunamis, soil liquefaction, coastal uplift/subsidence, volcanic eruptions, all of which pose a major threat to society. A reliable seismic hazard assessment requires establishing if such mega-events occurred in the past and determining their recurrence pattern. The Lake District (39-42°S) in South-Central Chile, located in the northern half of the 1960 earthquake rupture zone, contains several large, steep-sloped glacigenic lakes with high sedimentation rates, and whose sedimentary deposits are highly susceptible to earthquake-triggered slope instability. To establish the reoccurrence interval of earthquakes during the Late Holocene, we mapped the spatial distribution of seismically-induced sedimentary ‘event’ deposits and structures in each lake using very-high resolution seismic data, and collected a series of short gravity cores and long piston cores. Multi-proxy sedimentary analyses (color, magnetic susceptibility, density, geochemistry, grain size), radiocarbon dating, varve-counting, and tephro-stratigraphy were used to identify ‘event’ deposits in each core and correlate paleoseismic horizons across basins. The sediment sequences investigated contain four main types of earthquake-induced structures: 1) multiple mass-wasting deposits on a single stratigraphic level, which are relicts of a basin-wide, subaqueous slope instability ‘event’; 2) homogenite deposits in the deepest parts of steep basins indicative of lake seiches and tsunamis; 3) fluid-escape structures (e.g. sediment volcanoes), which reflect sudden liquefaction in buried mass-wasting deposits and subsequent vertical fluidization flow; 4) in-situ deformed units (e.g., contorted bedding) in nearly-flat layers, which reflect strong horizontal ground acceleration events. Comparison with historical earthquakes suggests the spatial extent, thickness, nature of

  14. Mobile LiDAR Measurement for Aerosol Investigation in South-Central Hebei, China

    NASA Astrophysics Data System (ADS)

    qin, kai; Wu, Lixin; Zheng, Yunhui; Wong Man, Sing; Wang, Runfeng; Hu, Mingyu; Lang, Hongmei; Wang, Luyao; Bai, Yang; Rao, Lanlan

    2016-04-01

    With the rapid industrialization and urbanization in China during the last decades, the increasing anthropogenic pollutant emissions have significantly caused serious air pollution problems which are adversely influencing public health. Hebei is one of the most air polluted provinces in China. In January 2013, an extremely severe and persistent haze episode with record-breaking PM2.5 outbreak affecting hundreds of millions of people occurred over eastern and northern China. During that haze episode, 7 of the top 10 most polluted cities in China were located in the Hebei Province according to the report of China's Ministry of Environmental Protection. To investigate and the spatial difference and to characterize the vertical distribution of aerosol in different regions of south-central Hebei, mobile measurements were carried out using a mini micro pulse LiDAR system (model: MiniMPL) in March 2014. The mobile LiDAR kit consisting of a MiniMPL, a vibration reduction mount, a power inverter, a Windows surface tablet and a GPS receiver were mounted in a car watching though the sunroof opening. For comparison, a fixed measurement using a traditional micro pulse LiDAR system (model: MPL-4B) was conducted simultaneously in Shijiazhuang, the capital of Hebei Province. The equipped car was driven from downtown Shijiazhuang by way of suburban and rural area to downtown Cangzhou, Handan, and Baoding respectively at almost stable speed around 100Km per hour along different routes which counted in total more than 1000Km. The results can be summarized as: 1) the spatial distribution of total aerosol optical depth along the measurement routes in south-central Hebei was controlled by local terrain and population in general, with high values in downtown and suburban in the plain areas, and low values in rural areas along Taihang mountain to the west and Yan mountain to the north; 2) obviously high AODs were obtained at roads crossing points, inside densely populated area and nearby

  15. Mesozoic thermal history and timing of structural events for the Yukon-Tanana Upland, east-central Alaska: 40Ar/39Ar data from metamorphic and plutonic rocks

    USGS Publications Warehouse

    Dusel-Bacon, C.; Lanphere, M.A.; Sharp, W.D.; Layer, P.W.; Hansen, V.L.

    2002-01-01

    We present new 40Ar/39Ar ages for hornblende, muscovite, and biotite from metamorphic and plutonic rocks from the Yukon-Tanana Upland, Alaska. Integration of our data with published 40Ar/39Ar, kinematic, and metamorphic pressure (P) and temperature (T) data confirms and refines the complex interaction of metamorphism and tectonism proposed for the region. The oldest metamorphic episode(s) postdates Middle Permian magmatism and predates the intrusion of Late Triassic (215-212 Ma) granitoids into the Fortymile River assemblage (Taylor Mountain assemblage of previous papers). In the eastern Eagle quadrangle, rapid and widespread Early Jurassic cooling is indicated by ???188-186 Ma 40Ar/39Ar plateau ages for hornblende from plutons that intrude the Fortymile River assemblage, and for metamorphic minerals from the Fortymile River assemblage and the structurally underlying Nasina assemblage. We interpret these Early Jurassic ages to represent cooling resulting from northwest-directed contraction that emplaced the Fortymile River assemblage onto the Nasina assemblage to the north as well as the Lake George assemblage to the south. This cooling was the final stage of a continuum of subduction-related contraction that produced crustal thickening, intermediate- to high-P metamorphism within both the Fortymile River assemblage and the structurally underlying Lake George assemblage, and Late Triassic and Early Jurassic plutonism in the Fortymile River and Nasina assemblages. Although a few metamorphic samples from the Lake George assemblage yield Jurassic 40Ar/39Ar cooling ages, most yield Early Cretaceous 40Ar/39Ar ages: hornblende ???135-115 Ma, and muscovite and biotite ???110-108 Ma. We interpret the Early Cretaceous metamorphic cooling, in most areas, to have resulted from regional extension and exhumation of the lower plate, previously tectonically thickened during Early Jurassic and older convergence.

  16. GIS Representation of Coal-Bearing Areas in North, Central, and South America

    USGS Publications Warehouse

    Tewalt, Susan J.; Kinney, Scott A.; Merrill, Matthew D.

    2008-01-01

    Worldwide coal consumption and international coal trade are projected to increase in the next several decades (Energy Information Administration, 2007). A search of existing literature indicates that in the Western Hemisphere, coal resources are known to occur in about 30 countries. The need exists to be able to depict these areas in a digital format for use in Geographic Information System (GIS) applications at small scales (large areas) and in visual presentations. Existing surficial geology GIS layers of the appropriate geologic age have been used as an approximation to depict the extent of coal-bearing areas in North, Central, and South America, as well as Greenland (fig. 1). Global surficial geology GIS data were created by the U.S. Geological Survey (USGS) for use in world petroleum assessments (Hearn and others, 2003). These USGS publications served as the major sources for the selection and creation of polygons to represent coal-bearing areas. Additional publications and maps by various countries and agencies were also used as sources of coal locations. GIS geologic polygons were truncated where literature or hardcopy maps did not indicate the presence of coal. The depicted areas are not adequate for use in coal resource calculations, as they were not adjusted for geologic structure and do not include coal at depth. Additionally, some coal areas in Central America could not be represented by the mapped surficial geology and are shown only as points based on descriptions or depictions from scientific publications or available maps. The provided GIS files are intended to serve as a backdrop for display of coal information. Three attributes of the coal that are represented by the polygons or points include geologic age (or range of ages), published rank (or range of ranks), and information source (published sources for age, rank, or physical location, or GIS geology base).

  17. Reduced admixture of North Atlantic Deep Water to the deep central South Pacific during the last two glacial periods

    NASA Astrophysics Data System (ADS)

    Molina-Kescher, Mario; Frank, Martin; Tapia, Raúl; Ronge, Thomas A.; Nürnberg, Dirk; Tiedemann, Ralf

    2016-06-01

    The South Pacific is a sensitive location for the variability of the global oceanic thermohaline circulation given that deep waters from the Atlantic Ocean, the Southern Ocean, and the Pacific Basin are exchanged. Here we reconstruct the deep water circulation of the central South Pacific for the last two glacial cycles (from 240,000 years ago to the Holocene) based on radiogenic neodymium (Nd) and lead (Pb) isotope records complemented by benthic stable carbon data obtained from two sediment cores located on the flanks of the East Pacific Rise. The records show small but consistent glacial/interglacial changes in all three isotopic systems with interglacial average values of -5.8 and 18.757 for ɛNd and 206Pb/204Pb, respectively, whereas glacial averages are -5.3 and 18.744. Comparison of this variability of Circumpolar Deep Water (CDW) to previously published records along the pathway of the global thermohaline circulation is consistent with reduced admixture of North Atlantic Deep Water to CDW during cold stages. The absolute values and amplitudes of the benthic δ13C variations are essentially indistinguishable from other records of the Southern Hemisphere and confirm that the low central South Pacific sedimentation rates did not result in a significant reduction of the amplitude of any of the measured proxies. In addition, the combined detrital Nd and strontium (87Sr/86Sr) isotope signatures imply that Australian and New Zealand dust has remained the principal contributor of lithogenic material to the central South Pacific.

  18. ERTS-1, earthquakes, and tectonic evolution in Alaska

    NASA Technical Reports Server (NTRS)

    Gedney, L.; Vanwormer, J.

    1974-01-01

    In comparing seismicity patterns in Alaska with ERTS-1 imagery, it is striking to see the frequency with which earthquake epicenters fall on, or near, lineaments visible on the imagery. Often these lineaments prove to be tectonics faults which have been mapped in the field. But equally as often, existing geologic and tectonic maps show no evidence of these features. The remoteness and inaccessibility of most of Alaska is responsible, in large part, for the inadequacy of the mapping. ERTS-1 imagery is filling a vital need in providing much of the missing information, and is pointing out many areas of potential earthquake hazard. Earthquakes in central and south-central Alaska result when the northeastern corner of the north Pacific lithospheric plate underthrusts the continent. North of Mt. McKinley, the seismicity is continental in nature and of shallow origin, with earthquakes occurring on lineaments, and frequently at intersections of lineaments. The shallower events tend to align themselves with lineaments visible on the imagery.

  19. Ground-water quality in Quaternary deposits of the central High Plains aquifer, south-central Kansas, 1999

    USGS Publications Warehouse

    Pope, Larry M.; Bruce, Breton W.; Hansen, Cristi V.

    2001-01-01

    Water samples from 20 randomly selected domestic water-supply wells completed in the Quaternary deposits of south-central Kansas were collected as part of the High Plains Regional Ground-Water Study conducted by the U.S. Geological Survey's National Water-Quality Assessment Program. The samples were analyzed for about 170 water-quality constituents that included physical properties, dissolved solids and major ions, nutrients and dissolved organic carbon, trace elements, pesticides, volatile organic compounds, and radon. The purpose of this study was to provide a broad overview of ground-water quality in a major geologic subunit of the High Plains aquifer. Water from five wells (25 percent) exceeded the 500-milligrams-per-liter of dissolved solids Secondary Maximum Contaminant Level for drinking water. The Secondary Maximum Contaminant Levels of 250 milligrams per liter for chloride and sulfate were exceeded in water from one well each. The source of these dissolved solids was probably natural processes. Concentrations of most nutrients in water from the sampled wells were small, with the exception of nitrate. Water from 15 percent of the sampled wells had concentrations of nitrate greater than the 10-milligram-per-liter Maximum Contaminant Level for drinking water. Water from 80 percent of the sampled wells showed nitrate enrichment (concentrations greater than 2.0 milligrams per liter), which is more than what might be expected for natural background concentrations. This enrichment may be the result of synthetic fertilizer applications, the addition of soil amendment (manure) on cropland, or livestock production. Most trace elements in water from the sampled wells were detected only in small concentrations, and few exceeded respective water-quality standards. Only arsenic was detected in one well sample at a concentration (240 micrograms per liter) that exceeded its proposed Maximum Contaminant Level (5.0 micrograms per liter). Additionally, one concentration of

  20. Permian Dollarhide formation, southern Smoky Mountains, south-central Idaho: depositional environment and petroleum potential

    SciTech Connect

    Geslin, J.K.; Link, P.K.

    1986-08-01

    The Permian Dollarhide formation occurs as an allochthon west of the Big Wood River in the Smoky Mountains of south-central Idaho. It is part of the Idaho Black Shale belt described during pioneering studies by W.E. Hall. The formation contains carbonaceous limestones, fine-grained calcareous sandstones, and carbonaceous, siliceous, or calcareous siltites. The rocks contain high amounts of carbonaceous matter and local concentrations of syngenetic silver, zinc, and lead. The Dollarhide has been contact-metamorphosed by the Cretaceous Idaho batholith. The carbonaceous matter occurs as graphite. However, the possibility exists that unmetamorphosed Dollarhide with petroleum source rock potential occurs outside the Smoky Mountains. It is also possible that other allochthons within the Black Shale belt, if unmetamorphosed, could have petroleum source rock material. Near Willow Creek, SW 1/4 Buttercup Mountain Quadrangle, Blaine and Camas Counties, Idaho, the Dollarhide is 2100 m thick and was deposited in a submarine slope environment. Sandy graded beds with convolute bedding, cross-bedding, synsedimentary folds, and load casts are evidence of turbidite and debris flow deposition. Interbedded laminated and massive siltites, which are more abundant upward, represent pelagic deposition between times of turbidite activity. Stratigraphic marker horizons with anomalously high amounts of carbonaceous material and trace metals represent more euxinic conditions in the basin. These markers serve as valuable correlation lines in the dominantly unfossiliferous strata.

  1. Deep Earthquake Mechanics Inferred From Fault-Plane Orientations in Central South America

    NASA Astrophysics Data System (ADS)

    Warren, L. M.; Biryol, C. B.; Beck, S. L.

    2007-05-01

    To place constraints on the physical mechanisms of deep earthquakes, we analyze the rupture properties of >30 intraslab earthquakes with MW ≥ 5.7 in central South America. For each earthquake, we combine a directivity analysis with mapping of the slip distribution to estimate the rupture vector and identify the fault plane. We can distinguish the fault plane of the focal mechanism for ~1/3 of these earthquakes. At intermediate depths, we test whether earthquakes result from dehydration embrittlement reactivating the steep, trenchward- dipping faults of the outer rise. After accounting for the angle of subduction, the outer-rise faults would be approximately vertical. This prediction disagrees with our identified fault planes between 100-300 km depth, which are all subhorizontal. Subhorizontal faults are consistent with only one of the two failure planes expected from the slab stress field, suggesting that the slab fabric or an isobaric rupture process may also influence fault- plane orientations. The occurrence of exclusively subhorizontal faults at intermediate depths agrees with previous studies in the Tonga-Kermadec and Middle America subduction zones. The similarity in results between the three subduction zones despite large differences in temperature, lithospheric thickness, subduction velocity, and subduction angle suggests that the earthquake-generating mechanism is controlled by pressure rather than temperature or other tectonic parameters. Deeper than 300 km, earthquakes slip along both subhorizontal and subvertical fault planes, in agreement with the ambient stress field.

  2. Deep Earthquake Mechanics Inferred From Fault-Plane Orientations in Central South America

    NASA Astrophysics Data System (ADS)

    Warren, L. M.; Biryol, C. B.; Beck, S. L.

    2007-12-01

    To place constraints on the physical mechanisms of deep earthquakes, we analyze the rupture properties of >30 intraslab earthquakes with MW >5.7 in central South America (15°--25°S). For all earthquakes, we perform a directivity analysis to estimate the rupture vector and identify the fault plane. After comparing the results with synthetics, we can distinguish the fault plane of the focal mechanism for ~1/3 of these earthquakes. For the largest earthquakes, we also invert for the slip distribution on the fault plane. At intermediate depths, we test whether earthquakes result from dehydration embrittlement reactivating the steep, trenchward-dipping faults of the outer rise. After accounting for the angle of subduction, these faults would be approximately vertical. This prediction contrasts with the orientation of faults identified between 100--300 km depth, which are all subhorizontal and instead suggest the creation of a new system of faults. The exclusive occurrence of subhorizontal faults agrees with previous studies in the Tonga-Kermadec and Middle America subduction zones. The similarity in results between the three subduction zones despite large differences in temperature, subduction velocity, and subduction angle suggests that the earthquake-generating mechanism is controlled by pressure rather than tectonic parameters. Deeper than 300 km, earthquakes occur along both subhorizontal and subvertical fault planes.

  3. Fluvial architecture of dinosaur bonebeds in the Cretaceous Judith River Formation, south-central Montana

    SciTech Connect

    Wilson, K.M. ); Dodson, P. ); Fiorillo, A.R. )

    1991-03-01

    Fluvial architecture of dinosaur bonebeds in the Cretaceous Judith River Formation, south-central Montana, has been the subject of intensive paleontological study for many years. However, little has been published on the sedimentology of the formation in this area. The authors have completed a preliminary field study of fluvial facies, with a view towards correcting this omission. Initial results include detailed facies descriptions and maps for five quarries along a line of transect stretching some 40 km parallel to depositional dip. Facies identified are predominantly overbank splays and levees, with common point bar/alluvial channel units and occasional small, possibly estuarine sand bodies in parts of the section. Shell beds (mainly oysters) and bedded, 1 m thick coals are also significant in some sections. Preliminary attempts at paleohydrology suggest river channels in some parts of the section were about 100 m wide and 2 m deep; however, other parts of the section exhibit much larger channel widths. Channel stacking is common. Preliminary results suggest a strong correlation between the occurrence of reddish brown carbonaceous silty shales, and dinosaur bone deposits.

  4. Thermal springs in the Boise River basin, south-central Idaho

    USGS Publications Warehouse

    Lewis, R.E.; Young, H.W.

    1982-01-01

    The Boise River Basin, characterized by steep, rugged mountains and narrow river valleys, drains an area of about 2,680 square miles in south-central Idaho. Granitic rocks of the Idaho batholith predominate in the basin. Temperature of waters from thermal springs in the basin range from 33 degrees to 87 degrees Celsius, are sodium carbonate type and are slightly alkaline. Dissolved-solids concentrations are less than 280 milligrams per liter. Estimated reservoir temperatures determined by the silica and sodium-potassium-calcium geothermometers range from 50 degrees to 98 degrees Celsius. Tritium concentrations in sampled thermal springs are near zero and indicate these waters were recharged prior to 1954. Stable-isotope data are not conclusive insofar as indicating a source area of recharge for the thermal springs in the basin. Thermal springs discharged at least 4,900 acre-feet of water in 1981, and the associated convective heat flux is 11,000,000 calories per second. (USGS)

  5. Greenhouse gas fluxes of a shallow lake in south-central North Dakota, USA

    USGS Publications Warehouse

    Tangen, Brian; Finocchiaro, Raymond; Gleason, Robert A.; Dahl, Charles F.

    2016-01-01

    Greenhouse gas (GHG) fluxes of aquatic ecosystems in the northern Great Plains of the U.S. represent a significant data gap. Consequently, a 3-year study was conducted in south-central North Dakota, USA, to provide an initial estimate of GHG fluxes from a large, shallow lake. Mean GHG fluxes were 0.02 g carbon dioxide (CO2) m−2 h−1, 0.0009 g methane (CH4) m−2 h−1, and 0.0005 mg nitrous oxide (N2O) m−2 h−1. Fluxes of CO2 and CH4 displayed temporal and spatial variability which is characteristic of aquatic ecosystems, while fluxes of N2O were consistently low throughout the study. Comparisons between results of this study and published values suggest that mean daily fluxes of CO2, CH4, and N2O fromLong Lakewere low, particularly when compared to the well-studied prairie pothole wetlands of the region. Similarly, cumulative seasonal CH4 fluxes, which ranged from 2.68–7.58 g CH4 m−2, were relatively low compared to other wetland systems of North America. The observed variability among aquatic ecosystems underscores the need for further research.

  6. Studying the NDVI dynamics features for vegetation monitoring method development in the south of Central Siberia

    NASA Astrophysics Data System (ADS)

    Pugacheva, Irina

    Monitoring of vegetation state can be based on studying their dynamics features. Effective methods of satellite data interpretation using spectral feature distinctions should be applied for this purpose. Studying the time series of Normalized Difference Vegetation Index (NDVI) during growth period is one of such approaches. The analysis of NDVI temporal profile shape allows to identify vegetation objects on satellite image. The NDVI curve transformation regularities during growth period are studied in the process of study carried out. Growth rate in specific phenological phases (growth of vegetative organs; maturation and fruiting) and extreme NDVI values during total growth period are detected. Growth rate is calculated as a NDVI curve slope. The NDVI dynamics of different vegetation types (agricultural crops - wheat, oats, buckwheat; abandoned fields of different age, meadow steppe, stony steppe, feather-grass steppe, flood meadow etc.), located in the south of Central Siberia (Krasnoyarsk krai, Khakasia), has been derived and analyzed. Results of this study are as the basis for developed software, which produces the automatic identification of canopy using Terra Modis satellite measurement data.

  7. Wisconsinan and Sangamonian climate interpreted from fossil ostracodes and vegetation in south-central Illinois

    SciTech Connect

    Curry, B.B. ); Forester, R.M. ); Zhu, Hong; Baker, R.G. . Dept. of Geology)

    1992-01-01

    The interpretation of paleoclimate during the late Illinoian, Sangamonian, and Wisconsinan Ages in the region of present south-central Illinois has been based on plant macrofossil, pollen, and vertebrate records. The ostracode records identify periods of flow across the basins and perhaps characteristics of groundwater discharge or recharge. Basins with the largest lake-to-catchment-area ratio were most sensitive to changes in effective moisture and hydrochemistry. The Sangamonian included three intervals during which the winters were warmer than those of historical record. These intervals are represented by sediment containing relatively abundant arboreal pollen, notably bald cypress and sweet gum, and the ostracode Heterocypris punctata, which lives in subtropical to tropical lakes and estuaries. H. punctata occurs with other ostracodes that require low salinity; their association indicates that precipitation typically exceeded evaporation and that the basin was affected by throughflow. The Sangamonian ended with two warm, wet episodes that sandwich an interval implying prairie lake conditions. Warmth-loving species are abundantly represented in upper Sangamonian sediments. Such warm, wet episodes are not known to have occurred in the Midcontinent during the Holocene. The top of the Sangamonian in all except the Pittsburgh Basin is capped by a layer of reworked sediment containing fluvial ostracodes and exotic mixtures of pollen, including both spruce and sweet gum but dominated by chenopods. The reworked layer is overlain by Wisconsinan sediment containing abundant pollen of boreal taxa and ostracodes that indicate basin throughflow.

  8. Controls on ground-water chemistry in the Horse Heaven Hills, south-central Washington

    USGS Publications Warehouse

    Steinkampf, W.C.; Bortleson, Gilbert C.; Packard, F.A.

    1985-01-01

    Miocene basaltic aquifers are the source of domestic and municipal water, and about 20,000 acre-feet of irrigation water annually, in the Horse Heaven Hills in south-central Washington State. Groundwater chemical variations derive from the hydraulic characteristics is of the geohydrologic system, from groundwater basalt reactions, and from irrigation. Some dissolved species concentrations increase with residence time; others decrease. Recharge area groundwaters are calcium magnesium sodium bicarbonate waters with sodium-adsorption ratios (SAR's) less than 1.0. They evolve to sodium potassium bicarbonate waters with SAR 's as high as 17. Glassy and cryptocrystalline phases of the basalt are the main sources of dissolved sodium. They dissolve by silicate hydrolysis in carbon dioxide charged waters that recharge the aquifer system. Dissolved silicon, iron, and aluminum concentrations are controlled by the solubilities of amorphous secondary alteration products, which order to silica phases, oxyhydroxides, and smectite. Carbonate mineral precipitation is induced by increasing pH from the hydrolysis reaction. Sodium and potassium concentrations increase until clinoptilolite saturation is reached and precipitation begins. Deviations from the general variation patterns are due to localized geologic structures which distort the groundwater flow system, and to the irrigation use of Columbia River water. (USGS)

  9. Preimpoundment water quality of Raystown Branch Juniata River and six tributary streams, south-central Pennsylvania

    USGS Publications Warehouse

    Williams, Donald R.

    1976-01-01

    The Raystown Branch Juniata River watershed, which is the main water source for Raystown Lake, is a 960-square-mile (2,490 square kilometres) drainage basin in south-central Pennsylvania. Preimpoundment water-quality data were collected on the Raystown Branch and six tributary st.reams in the basin. Specific conductance values varied inversely with water discharge. The pH values were extremely low only at the Shoup Run site. Dissolved oxygen concentrations observed at all sites indicated a relatively high oxygen saturation level throughout the year. Seasonal variations in nitrate-N and orthophosphate-P levels were measured at the main inflow station at Saxton, Pa. The highest concentrations of nitrate-N and orthophosphate-P occurred in the winter and spring months and the lowest concentrations were measured dur:l.ng the swnmer and fall. Bacteriological data indicated no excessive -amounts of fecal matter present at the inflows. Soil samples collected at four sites in the impoundment area were predominantly of the Barbour, Philo, and Basher series, which are considered to be highly fertile soils with silt-loam and sandy~loam textures. Morphological features of the lake basin and low nutrient levels at the inflows should prevent excessive weed growth around the lake perimeter.

  10. Magnetostratigraphy, paleomagnetic correlation, and deformation of Pleistocene deposits in the south central Puget Lowland, Washington

    NASA Astrophysics Data System (ADS)

    Hagstrum, Jonathan T.; Booth, Derek B.; Troost, Kathy G.; Blakely, Richard J.

    2002-04-01

    Paleomagnetic results from Pleistocene sedimentary deposits in the central Puget Lowland indicate that the region has experienced widespread deformation within the last 780 kyr. Three oriented samples were collected from unaltered fine-grained sediments mostly at sea level to determine the magnetostratigraphy at 83 sites. Of these, 47 have normal, 18 have reversed, and 18 have transitional (8 localities) polarities. Records of reversed- to normal-polarity transitions of the geomagnetic field were found in thick sections of silt near the eastern end of the Tacoma Narrows Bridge, and again at Wingehaven Park near the northern tip of Vashon Island. The transitional horizons, probably related to the Bruhnes-Matuyama reversal, apparently fall between previously dated Pleistocene sediments at the Puyallup Valley type section (all reversed-polarity) to the south and the Whidbey Island type section (all normal-polarity) to the north. The samples, in general, are of sufficient quality to record paleosecular variation (PSV) of the geomagnetic field, and a statistical technique is used to correlate horizons with significant agreement in their paleomagnetic directions. Our data are consistent with the broad structures of the Seattle uplift inferred at depth from seismic reflection, gravity, and aeromagnetic profiles, but the magnitude of vertical adjustments is greatly subdued in the Pleistocene deposits.

  11. Lake whitefish and lake herring population structure and niche in ten south-central Ontario lakes

    USGS Publications Warehouse

    Carl, Leon M.; McGuiness, Fiona

    2006-01-01

    This study compares simple fish communities of ten oligotrophic lakes in south-central Ontario. Species densities and population size structure vary significantly among these lake communities depending on fish species present beyond the littoral zone. Lake whitefish are fewer and larger in the presence of lake herring than in their absence. Diet analysis indicates that lake whitefish shift from feeding on both plankton and benthic prey when lake herring are absent to a primarily benthic feeding niche in the presence of lake herring. When benthic round whitefish are present, lake whitefish size and density decline and they move lower in the lake compared to round whitefish. Burbot are also fewer and larger in lakes with lake herring than in lakes without herring. Burbot, in turn, appear to influence the population structure of benthic coregonine species. Lower densities of benthic lake whitefish and round whitefish are found in lakes containing large benthic burbot than in lakes with either small burbot or where burbot are absent. Predation on the pelagic larvae of burbot and lake whitefish by planktivorous lake herring alters the size and age structure of these populations. As life history theory predicts, those species with poor larval survival appear to adopt a bet-hedging life history strategy of long-lived individuals as a reproductive reserve.

  12. Moho geometry along a north-south passive seismic transect through Central Australia

    NASA Astrophysics Data System (ADS)

    Sippl, Christian

    2016-04-01

    Receiver functions from a temporary deployment of 25 broadband stations along a north-south transect through Central Australia are used to retrieve crustal and uppermost mantle structural constraints from a combination of different methods. Using H-K stacking as well as receiver function inversion, overall thick crust with significant thickness variation along the profile (40 to ≥ 55 km) is found. Bulk crustal vp/vs values are largely in the felsic to intermediate range, with the southernmost stations on the Gawler Craton exhibiting higher values in excess of 1.8. A common conversion point (CCP) stacking profile shows three major discontinuities of the crust-mantle boundary: (1) a two-sided Moho downwarp beneath the Musgrave Province, which has previously been associated with the Neoproterozoic to early Cambrian Petermann Orogeny, (2) a Moho offset along the Redbank Shear Zone further north attributed to the Middle to Late Paleozoic Alice Springs Orogeny, and (3) another Moho offset further north, located at the boundary between the Davenport and Warramunga Provinces, which has not been imaged before. In all cases, the difference in crustal thickness between the two sides of the offset is > 8-10 km. Unlike the two southern Moho offsets, the northernmost one does not coincide with a prominent gravity anomaly. Its location and the absence of known reactivation events in the region make it likely that it belongs to a Proterozoic suture zone that marks a previously unknown block boundary within the North Australian Craton.

  13. Modeling and mapping regional land use/land cover change in South Central Texas

    NASA Astrophysics Data System (ADS)

    Ranatunga, T.; Messen, D.

    2014-12-01

    Houston-Galveston Area Council (H-GAC) conducted a land use/land cover (LULC) change detection study to generate information about the LULC changes in a 15-county area of South Central Texas. Such information is essential in regional planning, natural resource management, monitoring and modeling of environmental characteristics. The objectives of this study are (1) Identification of regional spatial patterns of each LULC conversion, (2) Estimation of the area coverage of each LULC conversion, and (3) Estimation of the net gain and losses of each LULC classes. To achieve these objectives, ArcGIS Spatial analysis functions and data management tools were employed in python environment. Change detection was estimated from 1992 to 2011 using datasets from NLCD (National Land Cover Database) 1992, NLCD 2001 and NOAA C-CAP (National Oceanic and Atmospheric Administration, Coastal Change Analysis Program) 2011. Through visual analysis and comparisons with aerial imagery, we established that NLCD 1992 and 2001 datasets contained more classification inaccuracies than the NOAA 2011 dataset. The misclassified cells in the 1992 and 2001 NLCD datasets were corrected to be consistent with the 2011 C-CAP dataset. The NLCD 2001 dataset was first corrected using a logical evaluation with 2011 classes in each pixel. Then the NLCD 1992 dataset was corrected using the correct 2001 dataset. After correcting 1992 dataset, a cell by cell comparison was conducted with the NOAA 2011 dataset, and individual changes were recorded.

  14. The formation of basal-type uranium deposits in south central British Columbia

    SciTech Connect

    Boyle, D.R.

    1982-08-01

    The basal-type uranium deposits in south central British Columbia occur within unconsolidated, late Miocene fluvial paleochannel sediments that overlie major fault zones within the Okanagan Highlands Intrusive Complex. Five uranium deposits have been outlined to date, of which the Blizzard (4,020 metric tons U) and Tyee (650 metric tons U) are the largest. The basement intrusive complex underlying the deposits varies in age from early Cretaceous to Eocene and is comprised of quartz monzonite, granodiorite, Coryell monzonite, porphyritic granite, and pegmatite. Uranium mineralization is present in the form of uranous (ningyoite) or uranyl (saleeite, autunite) phosphates coating clastic grains and filling voids. Because of very strong reducing conditions related to large concentrations of marcasite and organic material, ningyoite is the only uranium mineral in the Tyee deposit, whereas the Blizzard deposit contains a more complex assemblage of minerals (saleeite, autunite, ningyoite). The observed paragenetic sequence of mineral precipitation in the Blizzard deposit (autunite-saleeite-ningyoite) indicates that the uranyl minerals, saleeite and autunite, are primary. Investigations of the source of the ore-forming elements (U, Ca, Mg, PO/sub 4/) showed the deposits to be formed by the infiltration into fluvial sediments of deep-seated, structurally controlled, ground waters that migrated in a well-developed regional hydrologic system within the Complex. Research indicates that the ore-forming ground waters were cold, slightly bicarbonated (150-400 ppm), highly uraniferous (10-50 ppb), and slightly oxidizing (dissolved oxygen = 2-4 ppm).

  15. Validity of Drought Indices as Drought Predictors in the South-Central United States

    NASA Astrophysics Data System (ADS)

    Rohli, R. V.; Bushra, N.; Lam, N.; Zou, L.; Mihunov, V.; Reams, M.; Argote, J.

    2015-12-01

    Drought is among the most insidious types of natural disasters and can have tremendous economic and human health impacts. This research analyzes the relationship between two readily-accessible drought indices - the Palmer Drought Severity Index (PDSI) and Palmer Hydrologic Drought Index (PHDI) - and the damage incurred by such droughts in terms of monetary loss, over the 1975-2010 time period on monthly basis, for five states in the south-central U.S.A. Because drought damage in the Spatial Hazards Events and Losses Database for the United States (SHELDUSTM) is reported at the county level, statistical downscaling techniques were used to estimate the county-level PDSI and PHDI. Correlation analysis using the downscaled indices suggests that although relatively few months contain drought damage reports, in general drought indices can be useful predictors of drought damage at the monthly temporal scale extended to 12 months and at the county-wide spatial scale. The varying time lags between occurrence of drought and reporting of damage, perhaps due to varying resilience to drought intensity and duration by crop types across space, irrigation methods, and adaptation measures of the community to drought varies over space and time, are thought to contribute to weakened correlations. These results present a reminder of the complexities of anticipating the effects of drought but they contribute to the effort to improve our ability to mitigate the effects of incipient drought.

  16. Indoor radon and thoron concentrations in some towns of central and South Serbia.

    PubMed

    Vuckovic, Biljana; Gulan, Ljiljana; Milenkovic, Biljana; Stajic, Jelena M; Milic, Gordana

    2016-12-01

    This study presents the results of indoor radon and thoron activity concentrations of some municipalities in central and south part of Serbia: Krusevac, Brus, Blace and Kursumlija. Measurements were carried out in 60 dwellings during the winter season. Passive discriminative radon-thoron detectors known as UFO detectors were used. The mean values of indoor radon and thoron concentrations were 82 Bq m(-3) and 42 Bq m(-3), respectively. Population-weighted mean values were 76 Bq m(-3) and 40 Bq m(-3), respectively. 26.7% of dwellings had radon concentration higher than 100 Bq m(-3) (one location had even more than 300 Bq m(-3)). There are no statistically significant correlations of indoor radon and thoron concentrations neither with the period of house construction, nor with the existence of a basement. The results of this study represent the first step of investigating radon and thoron levels in these parts of Serbia and therefore could be the basis for creating a radon map.

  17. Magnetostratigraphy, paleomagnetic correlation, and deformation of pleistocene deposits in the south central Puget Lowland, Washington

    USGS Publications Warehouse

    Hagstrum, J.T.; Booth, D.B.; Troost, K.G.; Blakely, R.J.

    2002-01-01

    Paleomagnetic results from Pleistocene sedimentary deposits in the central Puget Lowland indicate that the region has experienced widespread deformation within the last 780 kyr. Three oriented samples were collected from unaltered fine-grained sediments mostly at sea level to determine the magnetostratigraphy at 83 sites. Of these, 47 have normal, 18 have reversed, and 18 have transitional (8 localities) polarities. Records of reversed- to normal-polarity transitions of the geomagnetic field were found in thick sections of silt near the eastern end of the Tacoma Narrows Bridge, and again at Wingehaven Park near the northern tip of Vashon Island. The transitional horizons, probably related to the Bruhnes-Matuyama reversal, apparently fall between previously dated Pleistocene sediments at the Puyallup Valley type section (all reversed-polarity) to the south and the Whidbey Island type section (all normal-polarity) to the north. The samples, in general, are of sufficient quality to record paleosecular variation (PSV) of the geomagnetic field, and a statistical technique is used to correlate horizons with significant agreement in their paleomagnetic directions. Our data are consistent with the broad structures of the Seattle uplift inferred at depth from seismic reflection, gravity, and aeromagnetic profiles, but the magnitude of vertical adjustments is greatly subdued in the Pleistocene deposits.

  18. Methane occurrence in groundwater of south-central New York State, 2012: summary of findings

    USGS Publications Warehouse

    Heisig, Paul M.; Scott, Tia-Marie

    2013-01-01

    A survey of methane in groundwater was undertaken to document methane occurrence on the basis of hydrogeologic setting within a glaciated 1,810-square-mile area of south-central New York that has not seen shale-gas resource development. The adjacent region in northeastern Pennsylvania has undergone shale-gas resource development from the Marcellus Shale. Well construction and subsurface data were required for each well sampled so that the local hydrogeologic setting could be classified. All wells were also at least 1 mile from any known gas well (active, exploratory, or abandoned). Sixty-six domestic wells and similar purposed supply wells were sampled during summer 2012. Field water-quality characteristics (pH, specific conductance, dissolved oxygen, and temperature) were measured at each well, and samples were collected and analyzed for dissolved gases, including methane and short-chain hydrocarbons. Carbon and hydrogen isotopic ratios of methane were measured in 21 samples that had at least 0.3 milligram per liter (mg/L) methane.

  19. Comparison of GNSS integrated water vapor and NWM reanalysis data over Central and South America

    NASA Astrophysics Data System (ADS)

    Fernández, Laura Isabel; Natali, Maria Paula; Meza, Amalia; Mendoza, Luciano; Bianchi, Clara

    2016-07-01

    Integrated water vapor (IWV) derived from Global Navigation Satellite Systems (GNSS) and Numerical Weather Models (NWM) reanalysis data were compared in order to assess the consistency between the different datasets over the extended geographical region of Central and South America. The analysis was performed for the seven years period between 2007 and 2013. We analyzed two different NWM: the European Centre for Medium-Range Weather Forecast (ECMWF) reanalysis data (ERA Interim) and the Modern-Era Retrospective analysis for Research and Applications (MERRA) from the National Aeronautics and Space Administration (NASA). The statistical analysis of the differences was performed in 110 GNSS sites (GPS + GLONASS), although the most interesting results came from the 73 sites which have more than 5 years of data. The selected area involves different climate types, from polar to tropical, and it is characterized by large temporal variability of the integrated total humidity content. Moreover, the scarce coverage of operational radio sounding stations is noticeable in large areas of the selected region; hence the contribution of IWV-GNSS is essential to improve the weather understanding. Considering that the atmospheric water vapor has a highly variable and complex distribution which knowledge is essential for weather prediction and local meteorological studies. This study aims to provide IWV-GNSS observations able to be assimilated by operational weather centers, for both prediction and simulation, as well for improving regional modeling.

  20. Quality of ground water in agricultural areas of the San Luis Valley, south-central Colorado

    USGS Publications Warehouse

    Edelmann, Patrick; Buckles, D.R.

    1984-01-01

    The quality of ground water in the principal agricultural areas of the San Luis Valley, south-central Colorado was evaluated using chemical analyses of water collected from 57 wells completed in the unconfined aquifer and from 25 wells completed in the confined aquifer. Ground water in both aquifers generally contains dissolved-solids concentrations of less than 500 milligrams per liter. In most areas, calcium is the principal cation in the ground water. Nitrite plus nitrate concentrations expressed as nitrogen, are generally less than 1 milligram per liter. However, the quality of ground water in certain areas may pose health and agricultural hazards. Water in the unconfined aquifer near Center contains high nitrite plus nitrate as nitrogen concentrations. The highest measured concentration in this area was 33 milligrams per liter. Water containing more than 1 milligram per liter of nitrite as nitrogen, or 10 milligrams per liter nitrate, as nitrogen, poses a potential health hazard for infants and should not be used for drinking. In addition, dissolved-solids concentration in the ground water in some areas is greater than 500 milligrams per liter and, if used for irrigation may reduce crop yields. (USGS)

  1. Regional and Seasonal Diet of the Western Burrowing Owl in South-Central Nevada

    SciTech Connect

    Derek B. Hall, Paul D. Greger, Jeffrey R. Rosier

    2009-04-01

    We examined diets of Western Burrowing Owls (Athene cunicularia hypugaea) based on contents of pellets and large prey remains collected year-round at burrows in each of the 3 regions in south central Nevada (Mojave Desert, Great Basin Desert, and Transition region). The most common prey items, based on percent frequency of occurrence, were crickets and grasshoppers, beetles, rodents, sun spiders, and scorpions. The most common vertebrate prey was kangaroo rats (Dipodomys spp.). True bugs (Hemiptera), scorpions, and western harvest mice (Reithrodontomys megalotis) occurred most frequently in pellets from the Great Basin Desert region. Kangaroo rats (Dipodomys spp.) and pocket mice (Perognathinae) were the most important vertebrate prey items in the Transition and Mojave Desert regions, respectively. Frequency of occurrence of any invertebrate prey was high (>80%) in samples year-round but dropped in winter samples, with scorpions and sun spiders exhibiting the steepest declines. Frequency of occurrence of any vertebrate prey peaked in spring samples, was intermediate for winter and summer samples, and was lowest in fall samples. With the possible exception of selecting for western harvest mice in the Great Basin Desert region, Western Burrowing Owls in our study appeared to be opportunistic foragers with a generalist feeding strategy.

  2. Mapping capacity to conduct health technology assessment in Central, Eastern and South-Eastern Europe

    PubMed Central

    Olry de Labry Lima, Antonio; García Mochón, Leticia; Caro Martínez, Araceli; Martín Ruiz, Eva; Espín Balbino, Jaime

    2016-01-01

    Aim To provide insights into the capacity to conduct health technology assessment (HTA) in Central, Eastern, and South-Eastern Europe (CESEE), taking account of technical, financial, networking, and human resources. Methods An e-mail survey of 257 CESEE key informants involved in HTA was undertaken between March and April 2014. Contact e-mail addresses were identified from the internet. The survey questionnaire consisted of 3 sections: i) characteristics of the organization performing HTA, (ii) networking in HTA, and (iii) resources allocated for HTA. Results The survey was completed by 41 respondents representing a wide range of institutions from CESEE countries (response rate of 19.8%). Less than a quarter of respondents reported that their institutions had HTA-specific budgets, whereas the majority indicated that their institutions participated in HTA networks either at domestic or international levels. Although almost half of respondents indicated that their institutions offered HTA training, a shortage in skills training was suggested as the main barrier to HTA. Conclusion This is the first survey to thoroughly assess the state of HTA capacity in the CESEE region. To strengthen HTA capacity, CESEE countries should increase financial, technical, and training resources. To strengthen collaboration, the European Union and other international bodies should assist existing HTA networks in fulfilling their regional activities through leadership, advocacy to local policymakers, funding, and technical assistance. PMID:26935616

  3. The environment of south-central Tunisia as observed on Landsat scene 206/036

    USGS Publications Warehouse

    Grolier, M.J.; Schultejann, P.A.

    1982-01-01

    One Landsat image in south-central Tunisia was analyzed to demonstrate the application of remote-sensing technology to regional development. A preliminary analysis included I) major landscape features; 2) gypsum-encrusted soils; and 3) phosphate-bearing beds exposed in the Gafsa mining district. The products specifically used for this report include: 1) A false-color composite (FCC), which had been linearly stretched to enhance contrast, and to which a modulation transfer function correction (a high-pass filter 3 pixels by 3 pixels wide) had been applied to enhance fine topographic relief. 2) A sinusoidally stretched false-color composite, on which mappable gypsum-encrusted soils and saline soils are detectable in greater detail than on the existing soil map of Tunisia at 1:500,000 scale. 3) A sinusoidally stretched band-ratio false-color composite, from which a thematic map of most phosphate-bearing beds in the Gafsa mining district was prepared. Recommendations for future Landsat image interpretation in Tunisia are offered.

  4. Ground beetles (Coleoptera, Carabidae) of the Hanford Nuclear Site in south-central Washington State

    PubMed Central

    Looney, Chris; Zack, Richard S.; LaBonte, James R.

    2014-01-01

    Abstract In this paper we report on ground beetles (Coleoptera: Carabidae) collected from the Hanford Nuclear Reservation and Hanford National Monument (together the Hanford Site), which is located in south-central Washington State. The Site is a relatively undisturbed relict of the shrub-steppe habitat present throughout much of the western Columbia Basin before the westward expansion of the United States. Species, localities, months of capture, and capture method are reported for field work conducted between 1994 and 2002. Most species were collected using pitfall traps, although other capture methods were employed. Trapping results indicate the Hanford Site supports a diverse ground beetle community, with over 90% of the 92 species captured native to North America. Four species collected during the study period are newly recorded for Washington State: Bembidion diligens Casey, Calosoma obsoletum Say, Pseudaptinus rufulus (LeConte), and Stenolophus lineola (Fabricius). Based on these data, the Site maintains a diverse ground beetle fauna and, due to its size and diversity of habitats, is an important repository of shrub-steppe biodiversity. PMID:24715791

  5. Drainage effects on stream nitrate-N and hydrology in south-central Minnesota (USA)

    USGS Publications Warehouse

    Magner, J.A.; Payne, G.A.; Steffen, J.

    2004-01-01

    Excessive nitrate-N in south-central Minnesota ditches and streams is related to land-use change, and may be contributing to the development of the zone of hypoxia in the Gulf of Mexico. Intensive land-use (agricultural management) has progressively increased as subsurface drainage has improved crop productivity over the past 25 years. We have examined water at varying scales for ??18O and, nitrate-N concentrations. Additionally, analysis of annual peak flows, and channel geomorphic features provided a measure of hydrologic change. Laboratory and field results indicate that agricultural drainage has influenced riverine source waters, concentrations of nitrate-N, channel dimensions and hydrology in the Blue Earth River (BER) Basin. At the mouth of the BER shallow ground water comprises the largest source water component. The highest nitrate-N concentrations in the BER and tributaries typically occurred in May and June and ranged from 7-34 mg L-1. Peak flows for the 1.01-2-yr recurrence intervals increased by 20-to-206% over the past 25 years. Geomorphic data suggest that small channels (ditches) were entrenched by design, whereas, natural channels incised. Increased frequent peak flows in the BER have created laterally confined channels that are disconnected from an accessible riparian corridor. Frequent access to a functioning riparian zone is important for denitrification.

  6. An arid-adapted middle Pleistocene vertebrate fauna from south-central Australia.

    PubMed

    Prideaux, Gavin J; Long, John A; Ayliffe, Linda K; Hellstrom, John C; Pillans, Brad; Boles, Walter E; Hutchinson, Mark N; Roberts, Richard G; Cupper, Matthew L; Arnold, Lee J; Devine, Paul D; Warburton, Natalie M

    2007-01-25

    How well the ecology, zoogeography and evolution of modern biotas is understood depends substantially on knowledge of the Pleistocene. Australia has one of the most distinctive, but least understood, Pleistocene faunas. Records from the western half of the continent are especially rare. Here we report on a diverse and exceptionally well preserved middle Pleistocene vertebrate assemblage from caves beneath the arid, treeless Nullarbor plain of south-central Australia. Many taxa are represented by whole skeletons, which together serve as a template for identifying fragmentary, hitherto indeterminate, remains collected previously from Pleistocene sites across southern Australia. A remarkable eight of the 23 Nullarbor kangaroos are new, including two tree-kangaroos. The diverse herbivore assemblage implies substantially greater floristic diversity than that of the modern shrub steppe, but all other faunal and stable-isotope data indicate that the climate was very similar to today. Because the 21 Nullarbor species that did not survive the Pleistocene were well adapted to dry conditions, climate change (specifically, increased aridity) is unlikely to have been significant in their extinction.

  7. The phylogeography and spatiotemporal spread of south-central skunk rabies virus.

    PubMed

    Kuzmina, Natalia A; Lemey, Philippe; Kuzmin, Ivan V; Mayes, Bonny C; Ellison, James A; Orciari, Lillian A; Hightower, Dillon; Taylor, Steven T; Rupprecht, Charles E

    2013-01-01

    The south-central skunk rabies virus (SCSK) is the most broadly distributed terrestrial viral lineage in North America. Skunk rabies has not been efficiently targeted by oral vaccination campaigns and represents a natural system of pathogen invasion, yielding insights to rabies emergence. In the present study we reconstructed spatiotemporal spread of SCSK in the whole territory of its circulation using a combination of Bayesian methods. The analysis based on 241 glycoprotein gene sequences demonstrated that SCSK is much more divergent phylogenetically than was appreciated previously. According to our analyses the SCSK originated in the territory of Texas ~170 years ago, and spread geographically during the following decades. The wavefront velocity in the northward direction was significantly greater than in the eastward and westward directions. Rivers (except the Mississippi River and Rio Grande River) did not constitute significant barriers for epizootic spread, in contrast to deserts and mountains. The mean dispersal rate of skunk rabies was lower than that of the raccoon and fox rabies. Viral lineages circulate in their areas with limited evidence of geographic spread during decades. However, spatiotemporal reconstruction shows that after a long period of stability the dispersal rate and wavefront velocity of SCSK are increasing. Our results indicate that there is a need to develop control measures for SCSK, and suggest how such measure can be implemented most efficiently. Our approach can be extrapolated to other rabies reservoirs and used as a tool for investigation of epizootic patterns and planning interventions towards disease elimination.

  8. Assessment of Hazards Associated with the Bluegill Landslide, South-Central Idaho

    USGS Publications Warehouse

    Ellis, William L.; Schuster, Robert L.; Schulz, William H.

    2004-01-01

    The Bluegill landslide, located in south-central Idaho, is part of a larger landslide complex that forms an area the Salmon Falls Creek drainage named Sinking Canyon Recent movement of the Bluegill landslide, apparently beginning sometime in late 1998 or early 1999, has caused a 4.5 ha area of the canyon rim to drop as much as 8 m and move horizontally several meters into the canyon. Upward movement of the toe of the landslide in the bottom of canyon has created a dam that impounds a lake approximately 2 km in length. The landslide is on public administered by the U.S. Bureau of Land Management (BLM). As part of ongoing efforts to address possible public safety concerns, the BLM requested that the U.S. Geological Survey (USGS) conduct a preliminary hazard assessment of the landslide, examine possible mitigation options, and identify alternatives for further study and monitoring of the landslide. This report presents the findings of that assessment based on a field reconnaissance of the landslide on September 24, 2003, a review of data and information provided by BLM and researchers from Idaho State University, and information collected from other sources.

  9. Constraining rates and trends of historical wetland loss, Mississippi River Delta Plain, south-central Louisiana

    USGS Publications Warehouse

    Bernier, Julie C.; Morton, Robert A.; Barras, John A.

    2006-01-01

    The timing, magnitude, and rate of wetland loss were described for five wetland-loss hotspots in the Terrebonne Basin of the Mississippi River delta plain. Land and water areas were mapped for 34 dates between 1956 and 2004 from historical National Wetlands Inventory (NWI) datasets, aerial photographs, and Landsat Thematic Mapper (TM) satellite images. Since 1956, the emergent land area at the five study areas in south-central Louisiana has decreased by about 50%. Comparison of the water-area curve derived from the 29 TM images with water-level records from the nearby Grand Isle, Louisiana tide gauge (NOS #8761724) clearly shows that changes in land and water areas fluctuate in response to variations in regional water levels. The magnitude of water-area fluctuations decreased from the 1980s to the 1990s as former areas of wet marsh within and immediately adjacent to the wetland-loss hotspots became permanently submerged. The most rapid wetland loss occurred during the late 1960s and 1970s. Peak wetland-loss rates during this period were two to four times greater than both the pre-1970s background rates and the most recent wetland-loss rates. These results provide constraints on predicting future delta-plain wetland losses and identify Landsat TM imagery as an important source for analyzing land- and water-area changes across the entire delta plain.

  10. Characterization and simulation of flow in the lower Arkansas River alluvial aquifer, south-central Kansas

    USGS Publications Warehouse

    Jian, Xiaodong; Combs, Lanna J.; Hansen, Cristi V.

    2004-01-01

    Large parts of the lower Arkansas, Ninnescah, and Walnut River Basins in south-central Kansasan area that includes Wichita, the largest city in Kansasare experiencing rapid population growth and, consequently, increasing demands on surface- and ground-water resources in addition to agricultural irrigation in the area. The quantity and quality of water available in the lower Arkansas, Ninnescah, and Walnut River Basins in Butler, Cowley, Sedgwick, and Sumner Counties are crucial as population and water use continue to increase in the region. A steady-state model was constructed to simulate flow in the Arkansas River alluvial aquifer between Wichita and Arkansas City. Calibration was achieved using March 2001 measured water levels and streamflow gain using long-term (19402001) streamflow records. Average recharge about 5 inches per year; average aquifer hydraulic conductivity was about 500 feet per day; well pumpage (average of reported 19982001 use) was 56 cubic feet per second; and net flow from the alluvial aquifer to streams in the modeled area was computed by hydrograph separation to be 157 cubic feet per second. Nine hypothetical simulations were conducted with ground-water pumpage varying from zero to double authorized pumpage (206 cubic feet per second). Net remaining aquifer thickness declined for the largest simulated pumpage increases in comparison to 19982001 average pumping, as did flow from the aquifer to the Arkansas River. Simulated aquifer thickness decreases were more pronounced in areas where pumpage is currently (2004) greatest.

  11. Oil and gas developments in South America, Central America, Caribbean area, and Mexico in 1987

    SciTech Connect

    Wiman, W.D.

    1988-10-01

    Exploration activity in South America, Central America, the Caribbean area, and Mexico in 1987 showed significant increases in seismic acquisition in Belize, Bolivia, Brazil, Costa Rica, Guatemala, Mexico, Paraguay, and Peru, and a decrease in Chile and Venezuela. Exploratory drilling increased in most major producing countries but was accompanied by a decline in development drilling. Most of the increase could be attributed to private companies fulfilling obligations under risk contracts; however, state oil companies in Bolivia, Chile, and Colombia showed significant increased activity, with only Mexico showing a decrease. Colombia again had a dramatic increase in production (29% from 1986). Noteworthy discoveries were made in Bolivia (Villamontes-1); Brazil, in the Solimoes basin (1-RUC-1-AM); Chile (Rio Honda-1); Colombia, in the Llanos basin (Austral-1, La Reforma-1, Libertad Norte-1, Cravo Este-1, and Cano Yarumal-1), in the Upper Magdalena basin (Toldado-1 and Los Mangos-1); Ecuador (Frontera-1, a joint-exploration venture with Colombia); Mexico, in the Chiapas-Tabasco region (Guacho-1 and Iridi-1), in the Frontera Norte area (Huatempo-1); Peru, in the Madre de Dios basin (Armihuari-4X); Trinidad (West East Queen's Beach-1); and Venezuela (Musipan-1X). Brazil's upper Amazon (Solimoes basin) discovery, Colombia's Upper Magdalena basin discoveries Toldado-1 and Los Mangos-1, Mexico's Chiapas-Tabasco discoveries, Peru's confirmation of the giant Cashiriari discovery of 1986, and Venezuela's success in Monagas state were the highlights of 1987. 5 figs., 8 tabs.

  12. Modeling water quality, temperature, and flow in Link River, south-central Oregon

    USGS Publications Warehouse

    Sullivan, Annett B.; Rounds, Stewart A.

    2016-09-09

    The 2.1-km (1.3-mi) Link River connects Upper Klamath Lake to the Klamath River in south-central Oregon. A CE-QUAL-W2 flow and water-quality model of Link River was developed to provide a connection between an existing model of the upper Klamath River and any existing or future models of Upper Klamath Lake. Water-quality sampling at six locations in Link River was done during 2013–15 to support model development and to provide a better understanding of instream biogeochemical processes. The short reach and high velocities in Link River resulted in fast travel times and limited water-quality transformations, except for dissolved oxygen. Reaeration through the reach, especially at the falls in Link River, was particularly important in moderating dissolved oxygen concentrations that at times entered the reach at Link River Dam with marked supersaturation or subsaturation. This reaeration resulted in concentrations closer to saturation downstream at the mouth of Link River.

  13. Hydrogeology and structure of the Bluewater Springs area south central Montana

    SciTech Connect

    Padilla, C.E.; Osborne, T.J.

    1996-06-01

    The Bluewater springs area in south central Montana was the site of oil and gas exploration in the first half of this century. Though no significant oil was found, artesian water wells produced over 3,000 gallons per minute. Artesian springs in the area produce tufa deposits over faulted, northwest dipping Mesozoic and upper Paleozoic sediments. Two new faults were mapped in the vicinity, one of these a high angle vertical fault dissects an anticline. The Tensleep and Madison aquifers (700-1,000 feet deep) leak water to the surface through faults and fractures, producing variable water quality depending on the minerals dissolved from overlying rock formations. Evaluation of limited aquifer data reveals the following: (1) hydraulic conductivity of 40,000 to 300,000 gpd/ft, (2) hydrostatic head greater than 400 feet above land surface. (3) Total dissolved solids concentrations were 2,370 ppm in Big Bluewater Springs, but only 1,200 ppm in a Tensleep well in the vicinity. Flowing wells 45 to 70 years old have failed leading to major yield reductions, and cessation of flow. Potentially corrosive groundwater coupled with excessive flow velocities and inadequate well construction has likely led to well failures. In response, major uncontrolled alterations of groundwater flow systems have occurred with outbreaks of new springs and sinkholes near failed wells. New wells must be carefully planned, constructed and tested to avoid excessive interference, depressurization and failure.

  14. Sea-floor geology in central Rhode Island Sound south of Sakonnet Point, Rhode Island

    USGS Publications Warehouse

    McMullen, K.Y.; Poppe, L.J.; Ackerman, S.D.; Worley, C.R.; Nadeau, M.A.; Van Hoy, M. V.

    2012-01-01

    The U.S. Geological Survey (USGS) and the National Oceanic and Atmospheric Administration (NOAA) are working together to study the sea floor along the northeastern coast of the United States. NOAA collected multibeam-echosounder data during hydrographic survey H11995 in a 63-square-kilometer area in central Rhode Island Sound, south of Sakonnet Point, Rhode Island. The USGS collected sediment samples, bottom video, and still photographs from 27 stations in this study area to verify an interpretation of the bathymetric data. Collected data are used to map areas of scour depressions and erosional outliers, megaripples, boulders, and relatively undisturbed modern marine sediments. In general, much of the eastern part of the study area, a submerged segment of the Harbor Hill-Roanoke Point-Charlestown-Buzzards Bay moraine, is bouldery. Bottom photography shows boulders are generally encrusted with hydrozoans, algae, and anemone. Scour depressions, presumably formed by long-period storm waves, and erosional outliers of Holocene sediments dominate the western part of the study area and several large areas in the east. The scour depressions tend to have coarser grained sediment than intervening erosional outliers. The coarseness likely creates turbulence in the water over these areas, which prevents fine-grained sediment deposition. Several small areas of megaripples are visible in the bathymetry data in the west. Other sandy areas are typically rippled, with burrows, worm tubes, and starfish present.

  15. Modeling saltwater upconing in a freshwater aquifer in south-central Kansas

    USGS Publications Warehouse

    Ma, T.-S.; Sophocleous, M.; Yu, Y.-S.; Buddemeier, R.W.

    1997-01-01

    The Great Bend Prairie freshwater alluvial aquifer in south-central Kansas overlies a bedrock brine aquifer of Permian age. The continuous extraction of freshwater mainly for irrigation in this area has accelerated the upward movement of the saltwater, resulting in the deterioration of water quality. Predicting saltwater upconing is critical for maintaining a long-term supply of water of good quality to the Groundwater Management District No. 5. This paper uses a numerical model to predict the effect of saltwater upconing on the salinity of pumped water. A sensitivity analysis was conducted for estimating the effects of uncertainties in model parameters on the numerical results. The most important factors affecting the salinity of discharged water are found to be the location and nature of clay layers in the aquifer, the pumping rate, the location of the well screen, and the hydraulic conductivities of the medium. The effect of uncertainties in aquifer porosity and dispersivity on salinity is appreciable but not substantial, whereas that of recharge from precipitation in the study area is relatively insignificant. In addition, a numerical model based on the field conditions observed at the Siefkes site was constructed and calibrated to reproduce and project the variation of measured water levels and discharged groundwater concentration. Finally, a number of practical management recommendations based on this study are presented.

  16. Adapting natural resource management to climate change: The South Central Oregon and Northern Rockies Adaptation Partnerships

    NASA Astrophysics Data System (ADS)

    Halofsky, J.; Peterson, D. L.

    2015-12-01

    Concrete ways to adapt to climate change are needed to help natural resource managers take the first steps to incorporate climate change into management and take advantage of opportunities to balance the negative effects of climate change. We recently initiated two science-management climate change adaptation partnerships, one with three national forests and one national park in south central Oregon, and the other with 16 national forests, three national parks and other stakeholders in the northern Rockies region. Goals of both partnerships were to: (1) synthesize published information and data to assess the exposure, sensitivity, and adaptive capacity of key resource areas, including water use, infrastructure, fisheries, and vegetation and disturbance; (2) develop science-based adaptation strategies and tactics that will help to mitigate the negative effects of climate change and assist the transition of biological systems and management to a warmer climate; (3) ensure adaptation strategies and tactics are incorporated into relevant planning documents; and (4) foster an enduring partnership to facilitate ongoing dialogue and activities related to climate change in the partnerships regions. After an initial vulnerability assessment by agency and university scientists and local resource specialists, adaptation strategies and tactics were developed in a series of scientist-manager workshops. The final vulnerability assessments and adaptation actions are incorporated in technical reports. The partnerships produced concrete adaptation options for national forest and other natural resource managers and illustrated the utility of place-based vulnerability assessments and scientist-manager workshops in adapting to climate change.

  17. Mitochondrial DNA diversity and origins of South and Central American goats.

    PubMed

    Amills, M; Ramírez, O; Tomàs, A; Badaoui, B; Marmi, J; Acosta, J; Sànchez, A; Capote, J

    2009-06-01

    We have analysed the genetic diversity of South and Central American (SCA) goats by partially sequencing the mitochondrial control region of 93 individuals with a wide geographical distribution. Nucleotide and haplotype diversities reached values of 0.020 +/- 0.00081 and 0.963 +/- 0.0012 respectively. We have also observed a rather weak phylogeographic structure, with almost 69% of genetic variation included in the within-breed variance component. The topology of a median-joining network analysis including 286 European, Iberian, Atlantic and SCA mitochondrial sequences was very complex, with most of the haplotypes forming part of independent small clusters. SCA sequences showed a scattered distribution throughout the network, and clustering with Spanish and Portuguese sequences occurred only occasionally, not allowing the distinguishing of a clear Iberian signature. Conversely, we found a prominent cluster including Canarian, Chilean, Argentinian and Bolivian mitochondrial haplotypes. This result was independently confirmed by constructing a Bayesian phylogenetic tree (posterior probability of 0.97). Sharing of mitochondrial haplotypes by SCA and Canarian goats suggests that goat populations from the Atlantic archipelagos, where Spanish and Portuguese ships en route to the New World used to stow food and supplies, participated in the foundation of SCA caprine breeds.

  18. Sequence stratigraphy and hydrocarbon potential of the Phu Khanh Basin offshore central Vietnam, South China Sea

    SciTech Connect

    Lee, G.H.; Watkins, J.S.

    1996-12-31

    The Phu Khanh Basin offshore central Vietnam is one of the few untested basins on the Vietnam margin of the South China Sea. Analysis of over 1,600 km of multi-channel seismic reflection data indicates that the Phu Khanh Basin follows a typical rift-margin order: faulted basement, synrift sedimentation, a breakup unconformity, and postrift sedimentation. Postrift sedimentation consists of a transgressive phase characterized by ramp-like depositional geometries followed by a regressive phase characterized by prograding sequences. An early middle Miocene unconformity separates these two phases. During the transgressive phase rising sea level provided favorable conditions for carbonate buildup development. The regressive interval contains a number of third-order depositional sequences composed of seismically resolvable lowstand, highstand, and rarely, transgressive systems tracts. Lacustrine sediments deposited in graben and half-graben lakes during the rifting stage are probably the principal source rocks. Fractured and/or weathered basement, carbonate complexes, basinfloor fans, and shallows water sands may have good reservoir quality. Potential traps include basement hills, carbonate complexes, fault taps, and stratigraphic traps within lowstand systems tracts. Hydrocarbon indicators such as flat spots, bright spots, gas chimneys with gas mounds on the seafloor occur at a number of locations.

  19. Sequence stratigraphy and hydrocarbon potential of the Phu Khanh Basin offshore central Vietnam, South China Sea

    SciTech Connect

    Lee, G.H. ); Watkins, J.S. )

    1996-01-01

    The Phu Khanh Basin offshore central Vietnam is one of the few untested basins on the Vietnam margin of the South China Sea. Analysis of over 1,600 km of multi-channel seismic reflection data indicates that the Phu Khanh Basin follows a typical rift-margin order: faulted basement, synrift sedimentation, a breakup unconformity, and postrift sedimentation. Postrift sedimentation consists of a transgressive phase characterized by ramp-like depositional geometries followed by a regressive phase characterized by prograding sequences. An early middle Miocene unconformity separates these two phases. During the transgressive phase rising sea level provided favorable conditions for carbonate buildup development. The regressive interval contains a number of third-order depositional sequences composed of seismically resolvable lowstand, highstand, and rarely, transgressive systems tracts. Lacustrine sediments deposited in graben and half-graben lakes during the rifting stage are probably the principal source rocks. Fractured and/or weathered basement, carbonate complexes, basinfloor fans, and shallows water sands may have good reservoir quality. Potential traps include basement hills, carbonate complexes, fault taps, and stratigraphic traps within lowstand systems tracts. Hydrocarbon indicators such as flat spots, bright spots, gas chimneys with gas mounds on the seafloor occur at a number of locations.

  20. Pliocene terrace gravels of the ancestral Yukon River near Circle, Alaska: Palynology, paleobotany, paleoenvironmental reconstruction and regional correlation

    USGS Publications Warehouse

    Ager, T.A.; Matthews, J.V.; Yeend, W.

    1994-01-01

    Gravels deposited by the ancestral Yukon River are preserved in terrace remnants on the margins of the Yukon River valley near the village of Circle in east-central Alaska. Plant fossils recovered from sandy silt lenses within these gravels include cones and needles of Picea and Larix and a variety of seeds. Seed types include several taxa which no longer grow in Alaska, such as Epipremnum, Prunus and Weigela. Pollen types recovered from these deposits represent tree and shrub taxa that grow in interior Alaska today, such as Picea, Larix, Betula and Alnus, as well as several taxa that no longer grow in interior Alaska today, such as Pinus, Tsuga, Abies and Corylus. Pollen of herb taxa identified include Gramineae, Cyperaceae, Caryophyllaceae, Compositae, Polemonium and Epilobium. The fossil flora from the gravels near Circle are similar and probably age-equivalent to the flora recovered from the Nenana Gravel in the Alaska Range 250 km to the south. Palynological and tectonic evidence summarized in this paper now suggests that the Nenana Gravel was deposited during the early and middle Pliocene. The presence of plant fossils of Tsuga, Abies, Pinus, Weigela and Prunus suggests that the mean annual temperature (MAT) of eastern interior Alaska during the early and middle Pliocene was perhaps 7-9??C warmer and less continental than today's MAT of -6.4??C. ?? 1994.

  1. Water-column cooling and sea surface salinity increase in the upwelling region off central-south Chile driven by a poleward displacement of the South Pacific High

    NASA Astrophysics Data System (ADS)

    Schneider, Wolfgang; Donoso, David; Garcés-Vargas, José; Escribano, Rubén

    2017-02-01

    Here we present results of direct observations of seawater temperature and salinity over the continental shelf off central-south Chile that shows an unprecedented cooling of the entire water column and an increase in upper layer salinity during 2002 to 2013. We provide evidence that this phenomenon is related to the intensification but mostly to a recent southward displacement of the South Pacific High over the same period, from 2007 on. This in turn has accelerated alongshore, equatorward, subtropical coastal upwelling favorable winds, particularly during winter, injecting colder water from below into the upper water column. Consequently, the environmental conditions on the shelf off central-south Chile shifted from a warmer (fresher) to a cooler (saltier) phase; water column temperature dropped from 11.7 °C (2003-2006) to 11.3 °C (2007-2012) and upper layer salinity rose by 0.25; water column stratification gradually decreased. The biological impacts of such abrupt cooling are apparently already happening in this coastal ecosystem, as recent evidence shows substantial changes in the plankton community and negative trends in zooplankton biomass over the same period.

  2. Multi-decadal trends in spring arrival of avian migrants to the central Arctic coast of Alaska: Effects of environmental and ecological factors

    USGS Publications Warehouse

    Ward, David; Helmericks, J.; Hupp, Jerry; McManus, L.; Budde, Michael; Douglas, David C.; Tape, K.D.

    2016-01-01

    Warming in the Arctic has caused the transition from winter to summer to occur weeks earlier over the last half century, yet little is known about whether avian migrants have altered their timing of arrival on breeding areas to match this earlier seasonal transition. Over a 50-yr period, we examined trends in the timing of the first arrival for 16 avian migrant species at the terminus of their northward migration along the central Arctic coast of Alaska and compared these trends to factors potentially influencing migration phenology. Date of first arrival occurred an average of 0.12 d yr−1 or 6 d (range = 3–10 d) earlier across all species and did not differ significantly among species between 1964 and 2013. Local climatic variables, particularly temperature, had a greater effect on a species first arrival date than did large-scale climatic predictors. First arrival date was 1.03 d earlier for every 1°C annual change in temperature, but there was nearly a 2-fold difference in the range of responses across species (0.69–1.33 d °C−1), implying that some species did better than others at timing their arrival with changing temperature. There was weak support for an influence of foraging strategy, migration distance, and flight path on timing of first arrival. Our findings, like others from temperate latitudes, indicate that avian migrants are responsive to changing environmental conditions, though some species appear to be more adaptive than others.

  3. Geochronology of the western and central Brooks Range, Alaska: Implications for the geologic evolution of the Anarraaq and Red Dog Zn-Pb-Ag deposits

    USGS Publications Warehouse

    Rombach, C.S.; Layer, P.W.

    2004-01-01

    A compilation of published geochronology of rocks and minerals from the western and central Brooks Range provides a framework for understanding the complex history of the Brooks Range and northern Alaska. A simplified timeline of events comprises (1) Devonian extension, (2) Mississippian extension and Zn-Pb-Ag mineralization, (3) a passive interval, (4) pre-Brooks Range orogeny rock-formation and thermal event, (5) inception of Brooks Range orogeny, (6) exhumation and the end of main-stage deformation, and (7) subsequent episodic deformation. This compilation is supplemented by new 40Ar/39Ar dates of white mica from the Anarraaq and Red Dog Zn-Pb-Ag (+ barite) deposits from the western Brooks Range. The deposits are hosted in black shale and carbonate rocks of the Late Mississippian-Early Pennsylvanian Kuna Formation. Quartz-pyrite-white mica grains in sedimentary rocks above the Anarraaq deposit yield an age of 195.0 ?? 2.0 Ma, and paragenetically late quartz-pyrite-white mica from the Main orebody at the Red Dog deposit has an age of 126.1 ?? 0.7 Ma. These white micas are much younger than the age of Zn-Pb-Ag mineralization at Red Dog (338 ?? 5.8 Ma Re-Os age of pyrite). The date for white mica from Anarraaq (???195 Ma) appears to be related to a large-scale thermal event in the region immediately before the inception of the Brooks Range orogeny. The white mica from the Red Dog deposit (???126 Ma) correlates with the later stages of the orogeny, a period of blueschist metamorphism, extension, and rapid exhumation, which varied with geographic location. These dates suggest that the Red Dog deposits underwent significant hydrothermal overprinting during multiple episodes of the Brooks Range orogeny. ?? 2004 by Economic Geology.

  4. Preliminary results, Central Gneiss Complex of the Coast Range batholith, southeastern Alaska: the roots of a high-K, calc-alkaline arc?

    USGS Publications Warehouse

    Barker, F.; Arth, Joseph G.

    1984-01-01

    The Central Gneiss Complex (CGC) of the Coast Range batholith is the oldest unit of the batholith east of Ketchikan, Alaska, being dated by the zircon UPb method (by T.W. Stern) at 128-140 Ma. Heterogeneous, layered, commonly migmatitic, orthogneiss of hornblende-biotite quartz diorite, tonalite, quartz monzodiorite and granodiorite compositions (IUGS terminology) form the major part of the CGC. These gneisses show a range of 50-65% SiO2 and are high in Al2O3 (c. 15-19%), K2O (1.5-4%) and Sr (800-900 ppm). Most major elements show coherent, typically magmatic trends with SiO2. La and Rb show maxima at ??? 58% SiO2. Initial 87Sr/86Sr ratios are relatively high and range from 0.7052 to 0.7066. Wallrocks of the CGC are mostly metagraywacke, pelite and metavolcanic rocks at amphibolite facies; they are geochemically dissimilar to the CGC. Major and minor elements of the CGC are very similar to those of high-K orogenic, calc-alkaline andesitic suites. The CGC may have formed largely by fractionation of mantle-derived, high AlKSr basaltic liquid in an ascending diapir, having hornblende, plagioclase, and biotite as major precipitating phases. The CGC probably represents the plutonic equivalent of a continental-margin or Andean arc that formed when the Taku terrane of the Insular belt on the west collided with the previously emplaced (but also allochthonous) Stikine terrane on the east in Late Jurassic or Early Cretaceous time. ?? 1984.

  5. Hydrological processes and chemical characteristics of low-alpine patterned wetlands, south-central New Zealand

    NASA Astrophysics Data System (ADS)

    Chagué-Goff, Catherine; Mark, Alan F.; Dickinson, Katharine J. M.

    2010-05-01

    SummaryPatterned wetlands in New Zealand are not only rare, but they are distinguished from their Northern Hemisphere counterparts by their vegetation and the supply of rainfall which is relatively free of pollution. Hydrological processes in two low-alpine patterned wetlands (5 and 220 ha) on block-faulted uplands in south-central South Island, New Zealand were investigated using hydraulic head gradients, and chemical and isotope data. There was no significant spatial variability in chemical parameters within either wetland, although the larger wetland is characterised by a lower trophic status than the smaller one. Ca 2+ concentrations and pH of surface water of both wetlands are within the range of that of Northern Hemisphere ombrotrophic/mesotrophic bogs and poor fens. Pool water chemistry only partially overlaps with the lower end of the Ca 2+ distribution for the Northern Hemisphere wetlands, likely to be caused by the low level of Ca 2+ in aeolian dust. The pH in the pools of the small wetland was generally higher, probably as a result of differing organic acid production by the Sphagnum and sedge species, both of which were common and dominant or sub-dominant in the wetlands. Some temporal variability was observed, possibly due to seasonal variations in plant uptake and/or rainfall. A steady increase in Na + concentrations in the pools over 4 years was tentatively attributed to an excess of supply from rainfall and/or groundwater. Cation and stable isotope data indicate strong evaporation in pools and surface water, despite the high ambient relative humidity, and mixing within the top of the wetland sequence. Stratigraphy indicates that peat formation has been interrupted by flooding or runoff, bringing mineral matter into the wetlands, particularly in the earlier development stages of the larger wetland. The peat sequence is thicker in the smaller wetland, reaching up to 2.8 m, with limited mineral input during wetland development. The relatively low p

  6. Particulate carbonate matter in snow from selected sites in the south-central Rocky Mountains

    USGS Publications Warehouse

    Clow, David W.; Ingersoll, George P.

    1994-01-01

    Trends in snow acidity reflect the balance between strong acid inputs and reactions with neutralizing materials. Carbonate dust can be an important contributor of buffering capacity to snow however, its concentration in snow is difficult to quantify because it dissolves rapidly in snowmelt. In snow with neutral or acidic pH, most calcite would dissolve during sample melting if snow samples were processed using standard techniques. Here a method is described for separating particulate carbonate matter from snow. Snow samples were melted in solutions close to saturation with calcite, decreasing the dissolution rate by a factor of 100-200 compared with natural melting of snow. Particulate matter larger than 0.45 ??m in diameter was then filtered from solution and analysed for carbonate content. Particulate carbonate matter concentrations are reported for 25 sites in the south-central Rocky Mountains. Results are compared with Ca2+ and H+ concentrations and regional trends are evaluated. In Colorado, mean particulate carbonate in snow was 43 ??g kg-1 at sampling sites in the southern mountains and only 4 ??g kg-1 at sites in the northern mountains. The higher calcite concentrations in the south probably are related to the proximity of sampling sites to major outcrops of limestone. Particulate carbonate at sampling sites in Utah and Wyoming ranged from 3-35 ??g kg-1. The levels of particulate calcite measured in snow samples are sufficient to neutralize an average of 0.4 ??eq H+ kg-1 snow. Strong acid anion concentrations in samples from east of Craig, Colorado, were 30-50% higher than in samples from the Colorado Front Range, but H+ concentrations were 400-600% higher east of Craig. Relatively low Ca2+ concentrations in the samples from east of Craig indicate that the difference in snow acidity was due mostly to lower concentrations of neutralizing materials.Trends in snow acidity reflect the balance between strong acid inputs and reactions with neutralizing materials

  7. GREYBULL SANDSTONE PETROLEUM POTENTIAL ON THE CROW INDIAN RESERVATION, SOUTH-CENTRAL MONTANA

    SciTech Connect

    David A. Lopez

    2000-12-14

    Evaluation of the Lower Cretaceous Greybull Sandstone on the Crow Indian Reservation for potential stratigraphic traps in the valley-fill sandstone was the focus of this project. The Crow Reservation area, located in south-central Montana, is part of the Rocky Mountain Foreland structural province, which is characterized by Laramide uplifts and intervening structural basins. The Pryor and Bighorn mountains, like other foreland uplifts, are characterized by asymmetrical folds associated with basement-involved reverse faults. The reservation area east of the mountains is on the northwestern flank of the Powder River Basin. Therefore, regional dips are eastward and southeastward; however, several prominent structural features interrupt these regional dips. The nearly 4,000 mi{sup 2} reservation is under explored but has strong potential for increased oil and gas development. Oil and gas production is well established in the Powder River Basin of Wyoming to the south as well as in the areas north and west of the reservation. However, only limited petroleum production has been established within the reservation. Geologic relations and trends indicate strong potential for oil and gas accumulations, but drilling has been insufficient for their discovery. The Greybull Sandstone, which is part of the transgressive systems tract that includes the overlying Fall River Sandstone, was deposited on a major regional unconformity. The erosional surface at the base of the Greybull Sandstone is the +100 Ma, late Aptian-Early Albian regional unconformity of Weimer (1984). This lowstand erosional surface was controlled by a basin-wide drop in sea level. In areas where incised Greybull channels are absent, the lowstand erosional unconformity is at the base of the Fall River Sandstone and equivalent formations. During the pre-Greybull lowstand, sediment bypassed this region. In the subsequent marine transgression, streams began to aggrade and deposit sand of the lower Greybull Sandstone

  8. The importance of subarctic intertidal habitats to shorebirds: A study of the central Yukon-Kuskokwim Delta, Alaska

    USGS Publications Warehouse

    Gill, Robert E.; Handel, Colleen M.

    1990-01-01

    A 6-year study of shorebird use of intertidal habitats of the Yukon-Kuskokwim Delta revealed this area to be one of the premiere sites for shorebirds throughout the Holarctic and worthy of designation as a Hemispheric Shorebird Reserve in the Western Hemisphere Shorebird Reserve Network. The study area, which covered 10% (300 km2) of the delta's intertidal flats, regularly hosted 17 species of shorebirds between late April and mid-October. The greatest use was during the postbreeding period (late June-October), when Dunlins (Calidris alpina), Western Sandpipers (C. mauri), and Rock Sandpipers (C. ptilocnemis), each with large local nesting populations, accounted for 95% of the shorebirds recorded. Peak counts during autumn approached 300,000 birds. Considering the seasonal occurrence and turnover of populations, we estimate 1-2 million shorebirds use the central delta each year. The delta supports large fractions of the Pacific Rim or world populations of Bar-tailed Godwits (Limosa lapponica), Black Turnstones (Arenaria melanocephala), Red Knots (C. canutus), Western Sandpipers, Dunlins, and Rock Sandpipers. Densities of shorebirds using the central delta's four major bays and connecting coastal areas peaked at 950 shorebirds/km2 in early September. Hazen Bay frequently hosted more than 1,200 shorebirds/km2. Postbreeding shorebirds used intertidal habitats in three distinct patterns according to age class. For most species (n = 7), there was a period when adults appeared first, followed by a brief interval when adults and juveniles mixed, then by a prolonged period when only juveniles remained. In the second pattern (n = 3 species), adults moved onto the intertidal flats first, were later joined by juveniles for a prolonged staging period, then migrated with them. In the third pattern (n = 3 species), only juveniles used the delta's intertidal habitat. Temporal segregation among species and age groups may minimize competition for food and thereby allow the delta to

  9. Preface to the special issue on "Regional moment tensors and stress field in South and Central America"

    NASA Astrophysics Data System (ADS)

    Audemard, Franck; Zahradnik, Jiri; Assumpção, Marcelo

    2016-11-01

    This special issue follows from the Symposium "Regional Moment Tensor Solutions: advances and new applications" held in Bogotá, Colombia, at the I Regional Assembly of the IASPEI's Latin American and Caribbean Seismological Commission (LACSC) in 2014. Seven papers are presented dealing with determination of moment tensors, focal mechanisms and the stress field in Central and South America. The study areas of each paper are indicated in the index Map of Fig. 1.

  10. Amanita viscidolutea, a new species from Brazil with a key to Central and South American species of Amanita section Amanita.

    PubMed

    Menolli, Nelson; Capelari, Marina; Baseia, Iuri Goulart

    2009-01-01

    We described and illustrated Amanita viscidolutea sp. nov. from specimens collected in the state of Rio Grande do Norte, northeastern Brazil. The main characteristics of the new species are its yellow pileus with white margin, the viscidity of the pileal surface, an exannulate stipe and inamyloid basidiospores. We also present an artificial dichotomous key to Central and South American species of Amanita (subgenus Amanita) section Amanita.

  11. Paleogeographic and Tectonic Implications of Paleomagnetic Data From Mexico, Central America, Northern South America and Caribbean Arc

    NASA Astrophysics Data System (ADS)

    Urrutia-Fucugauchi, J.; Alva-Valdivia, L.; Goguitchaishvili, A.; Soler-Arechalde, A.; Benammi, M.

    2006-05-01

    Results from recent paleomagnetic studies in Mexico, Cuba, Dominican Republic, El Salvador, Nicaragua and Costa Rica are summarized and discussed in terms of their tectonic and paleogeographic implications. Rock units studied range in age from Jurassic to Neogene. Additionally, we present an updated paleomagnetic database for widely distributed localities from Mexico, Central America, northern South America and the Caribbean. Paleomagnetic constraints are analyzed within a paleogeographic and tectonic framework, which departs from models for continental plate collision of North and South America, including intervening terranes, and subsequent evolution of the Atlantic bordering continental land masses. Most paleoreconstructions imply an allochthonous nature for most of Mexico, Central America and Caribbean. Mesozoic and early Cenozoic evolution of the region has been dominated by Pangea assembly and subsequent drift apart of major continental plates of North and South America following break up of the Pangea supercontinent. Separation of North and South America and opening of the central North Atlantic Ocean permitted development of the Gulf of Mexico and eastward motion of the proto Caribbean plate. Terrane accretion, block rotation and lateral movements are recorded for terranes in Mexico, associated with terrane amalgamation, Gulf of Mexico opening, plate tectonic re-organizations, margin truncation and compression/extensional intra-plate and margin deformation. Paleomagnetic data from the Antilles arc document the occurrence of vertical-axis block rotations, associated with arc development and pull-apart basins. Data from volcanic units in El Salvador do not support occurrence of vertical-axis rotations during the Neogene, as had been proposed for the Central American arc. Paleomagnetic studies provide quantitative information on paleolatitude, latitudinal translations and relative rotations of large and small tectonic blocks, assisting in distinguishing and

  12. Concentrations of Selected Pharmaceuticals and Antibiotics in South-Central Pennsylvania Waters, March through September 2006

    USGS Publications Warehouse

    Loper, Connie A.; Crawford, J. Kent; Otto, Kim L.; Manning, Rhonda L.; Meyer, Michael T.; Furlong, Edward T.

    2007-01-01

    This report presents environmental and quality-control data from analyses of 15 pharmaceutical and 31 antibiotic compounds in water samples from streams and wells in south-central Pennsylvania. The analyses are part of a study by the U.S. Geological Survey (USGS) in cooperation with the Pennsylvania Department of Environmental Protection (PADEP) to define concentrations of selected emerging contaminants in streams and well water in Pennsylvania. Sampling was conducted at 11 stream sites and at 6 wells in 9 counties of south-central Pennsylvania. Five of the streams received municipal wastewater and 6 of the streams received runoff from agricultural areas dominated by animal-feeding operations. For all 11 streams, samples were collected at locations upstream and downstream of the municipal effluents or animal-feeding operations. All six wells were in agricultural settings. A total of 120 environmental samples and 21 quality-control samples were analyzed for the study. Samples were collected at each site in March/April, May, July, and September 2006 to obtain information on changes in concentration that could be related to seasonal use of compounds. For streams, 13 pharmaceuticals and 11 antibiotics were detected at least 1 time. Detections included analytical results that were estimated or above the minimum reporting limits. Seventy-eight percent of all detections were analyzed in samples collected downstream from municipal-wastewater effluents. For streams receiving wastewater effluents, the pharmaceuticals caffeine and para-xanthine (a degradation product of caffeine) had the greatest concentrations, 4.75 ug/L (micrograms per liter) and 0.853 ug/L, respectively. Other pharmaceuticals and their respective maximum concentrations were carbamazepine (0.516 ug/L) and ibuprofen (0.277 ug/L). For streams receiving wastewater effluents, the antibiotic azithromycin had the greatest concentration (1.65 ug/L), followed by sulfamethoxazole (1.34 ug/L), ofloxacin (0.329 ug

  13. Seismic stratigraphy and late Quaternary shelf history, south-central Monterey Bay, California

    USGS Publications Warehouse

    Chin, J.L.; Clifton, H.E.; Mullins, H.T.

    1988-01-01

    The south-central Monterey Bay shelf is a high-energy, wave-dominated, tectonically active coastal region on the central California continental margin. A prominent feature of this shelf is a sediment lobe off the mouth of the Salinas River that has surface expression. High-resolution seismic-reflection profiles reveal that an angular unconformity (Quaternary?) underlies the entire shelf and separates undeformed strata above it from deformed strata below it. The Salinas River lobe is a convex bulge on the shelf covering an area of approximately 72 km2 in water depths from 10 to 90 m. It reaches a maximum thickness of 35 m about 2.5 km seaward of the river mouth and thins in all directions away from this point. Adjacent shelf areas are characterized by only a thin (2 to 5 m thick) and uniform veneer of sediment. Acoustic stratigraphy of the lobe is complex and is characterized by at least three unconformity-bounded depositional sequences. Acoustically, these sequences are relatively well bedded. Acoustic foresets occur within the intermediate sequence and dip seaward at 0.7?? to 2.0??. Comparison with sedimentary sequences in uplifted onshore Pleistocene marine-terrace deposits of the Monterey Bay area, which were presumably formed in a similar setting under similar processes, suggests that a general interpretation can be formulated for seismic stratigraphic patterns. Depositional sequences are interpreted to represent shallowing-upwards progradational sequences of marine to nonmarine coastal deposits formed during interglacial highstands and/or during early stages of falling sea level. Acoustic foresets within the intermediate sequence are evidence of seaward progradation. Acoustic unconformities that separate depositional sequences are interpreted as having formed largely by shoreface planation and may be the only record of the intervening transgressions. The internal stratigraphy of the Salinas River lobe thus suggests that at least several late Quaternary

  14. Reconnaissance of water quality in the High Plains Aquifer beneath agricultural lands, south-central Kansas

    USGS Publications Warehouse

    Stullken, L.E.; Stamer, J.K.; Carr, J.E.

    1987-01-01

    The High Plains of western Kansas was one of 14 areas selected for preliminary groundwater quality reconnaissance by the U.S. Geological Survey 's Toxic Waste--Groundwater Contamination Program. The specific objective was to evaluate the effects of land used for agriculture (irrigated cropland and non-irrigated rangeland) on the water in the High Plains aquifer. Conceptual inferences, based on the information available, would lead one to expect groundwater beneath irrigated cropland to contain larger concentrations of sodium, sulfate, chloride, nitrite plus nitrate, and some water soluble pesticides than water beneath non-irrigated land (range-land) The central part of the Great Bend Prairie, an area of about 1,800 sq mi overlying the High Plains aquifer in south-central Kansas, was selected for the study of agricultural land use because it has sand soils, a shallow water table, relatively large annual precipitation, and includes large areas that are exclusively irrigated cropland or non-irrigated rangeland. As determined by a two-tailed Wilcoxon rank-sum test, concentrations of sodium and alkalinity were significantly larger at the 95% confidence level for water samples from beneath irrigated cropland than from beneath rangeland. No statistically significant difference in concentrations of sulfate, chloride, nitrite plus nitrate, and ammonia, was detected. Concentrations of 2,4-D found in water samples from beneath the rangeland were larger at the 99% confidence level as compared to concentrations of 2,4-D in samples from beneath irrigated cropland. Larger concentrations of sodium and alkalinity were found in water beneath irrigated cropland, and the largest concentration of the pesticide atrazine (triazines were found in three samples) was found in water from the only irrigation well sampled. The sodium and atrazine concentrations found in water from the irrigation well support the premise that water-level drawdown develops under irrigated fields. This diverts

  15. Stream and aquifer biology of south-central Texas; a literature review, 1973-97

    USGS Publications Warehouse

    Ourso, R.T.; Hornig, C.E.

    1999-01-01

    This report summarizes in table format 32 aquatic vertebrate (primarily fish), 54 aquatic invertebrate, and 13 aquatic plant studies available for the area of the South-Central Texas study unit of the U.S. Geological Survey National Water-Quality Assessment. The studies, published mostly during 1973?97, pertain to the Guadalupe, San Antonio, and Nueces River Basins, the San Antonio-Nueces and Nueces-Rio Grande Coastal Basins, and the Edwards aquifer where it underlies the upper parts of the three river basins. The biology of the study-unit streams is determined mostly by the characteristics of the ecoregions they transect?the Edwards Plateau, Texas Blackland Prairies, East Central Texas Plains, Western Gulf Coastal Plain, and Southern Texas Plains. About 20 percent of the previous fish and invertebrate studies and about 75 percent of the aquatic plant surveys have centered on Comal Springs in Comal County and San Marcos Springs in Hays County. Although several important studies are available for the San Antonio region, documentation of aquatic biology for the remainder of the study unit is relatively sparse. The streams in the study unit, particularly in the Edwards Plateau, support three dominant biological groups?fish, aquatic invertebrates, and plants. Potential threats to these organisms include impoundments and flood-control projects, siltation from erosion, ground-water pumping, recreational activities, wastewater discharge, and introduction of non-native species. More than 30 non-native fish, invertebrate, and plant species have been introduced into the region. Of the 19 aquatic species Federally listed as endangered or threatened in Texas, 8 are associated with springs and spring runs in the study unit. All of the endangered species in the study unit are associated with springs and spring runs. A large number of endemic species in the study unit are associated with subterranean aquatic ecosystems, most likely a consequence of the unique proximity of the

  16. Cancer in HIV-infected Persons from the Caribbean, Central and South America

    PubMed Central

    Fink, Valeria I.; Shepherd, Bryan E.; Cesar, Carina; Krolewiecki, Alejandro; Wehbe, Firas; Cortés, Claudia P.; Crabtree-Ramírez, Brenda; Padgett, Denis; Shafaee, Maryam; Schechter, Mauro; Gotuzzo, Eduardo; Bacon, Melanie; McGowan, Catherine; Cahn, Pedro; Masys, Daniel

    2011-01-01

    Background HIV infected individuals have heightened cancer risk. With the advent of HAART, the frequency of some AIDS defining cancers (ADC) has decreased while certain non-AIDS defining cancers (NADC) are becoming more frequent. Cancers among HIV-infected individuals in Latin American and the Caribbean have not yet been carefully studied. Methods Cancer cases among the Caribbean, Central and South American network for HIV Research (CCASAnet) cohort were identified reviewing clinical records and preexisting databases. Results There were 406 cancers reported: 331 ADC (224 Kaposi´s sarcomas and 98 non Hodgkin lymphomas). Most frequent NADC (n=75) were Hodgkin lymphoma and skin cancers. Seventy-three percent of NADC and 45% of ADC were diagnosed >1 year after HIV diagnosis. 56% of ADC occurred before HAART start. Median time from HAART start until cancer diagnosis was 2.5 years for NADC and 0.5 years for ADC (p=<0.001). Within 3372 HAART starters, 158 were diagnosed with 165 cancers (82.4% ADC); 85 cases were previous to or concomitant with HAART initiation. Incidence of cancer after HAART initiation in 8080 person-years of follow-up was 7.2 per 1000 person-years (95%CI= 5.5–9.3) for ADC and 2.7 (95%CI= 1.8–4.1) for NADC; incidence was higher in the first two months, particularly for ADC (47.6). A pre-HAART ADC was a predictor of mortality after adjusting for age, sex, and CD4 at HAART initiation. Conclusions ADC were the most frequent cancers in this region and were often diagnosed close to HIV diagnosis and HAART start. Incidence of cancer was highest around HAART initiation. PMID:21239992

  17. Spring-migration ecology of Northern Pintails in south-central Nebraska

    USGS Publications Warehouse

    Pearse, Aaron T.; Krapu, Gary L.; Cox, Robert R.; Davis, Bruce E.

    2011-01-01

    Spring-migration ecology of staging Northern Pintails, Anas acuta, was investigated in south-central Nebraska, USA. Habitat associations, local movements, settling patterns, arrival dates, residency times and survival were estimated from 71 radiomarked pintails during spring 2001, 2003 and 2004, and diet determined from 130 females collected during spring 1998 and 1999. Seventy-two percent of pintail diurnal locations were in palustrine wetlands, 7% in riverine wetlands, 3% in lacustrine wetlands, 6% in municipal sewage lagoons and irrigation reuse pits and 10.5% in croplands. Emergent wetlands with hemi-marsh conditions were used diurnally more often than wetlands with either open or closed vegetation structures. Evening foraging flights averaged 4.3 km (SE = 0.6) and 72% were to cornfields. In accord with these findings, 87% of 93 pintails collected during spring 1998 and 1999 returning to evening roosts consumed corn, which represented 84% dry mass of all foods. Pintails collected on non-cropped wetlands ingested invertebrates and seeds from wetland plants more frequently than birds returning to roost. Radiomarked pintails arrived in Nebraska on 7 March 2003 and 18 February 2004; average arrival date was six days earlier during 2004 compared to 2003. Residency time for individuals varied greatly (1–40 days) yet yearly means were similar and averaged 9.5 days within the region. No mortality was detected for 71 birds monitored over 829 exposure days. Conservation planners linking population dynamics and habitat conditions at spring-staging areas need to focus on pintail body condition during spring and its connection with reproductive success and survival during the breeding season.

  18. Metamorphic evolution of pelitic-semipelitic granulites in the Kon Tum massif (south-central Vietnam)

    NASA Astrophysics Data System (ADS)

    Tích, Vu Van; Leyreloup, Andrey; Maluski, Henry; Lepvrier, Claude; Lo, Chinh-hua; Vượng, Nguyễn V.

    2013-09-01

    Pelitic and semipelitic anatectic granulites form one of the major lithological units in Kan Nack complex of the Kon Tum massif (in south-central Vietnam), which comprises HT metamorphic and magmatic rocks including granulites and charnockites is classically regarded as the older part of the Gondwana-derived Indosinia terrain. Metamorphic evolution study of pelitic granulite, the most abundant among granulites exposed in this massif, facilitates to understand that tectonic setting take place during the Indosinian time. The paragenetic assemblages, mineral chemistry, thermobarometry and P-T evolution path of pelitic-semipelitic granulites from Kon Tum massif has been studied in detail. Petrographic feature demonstrates that the pelitic granulite experienced prograde history, from pregranulitic conditions in the amphibolite facies up to the peak granulitic assemblages. Successive prograde reactions led to the temperature-climax giving rise to assemblages with cordierite-hercynite and cordierite-hercynite-K-feldspar. Then, as attested by the mineralogic association occurring in cordieritic coronas, these rocks have been affected by retrograde conditions coeval with a decrease of the pressure. Thermobarometic results show that the highest temperature obtained by ksp/pl thermometry is 850 °C and the highest pressure obtained by GASP (Garnet Alumino-Silicate Plagioclase) is 7.8 kbar. The obtained clockwise P-T evolution path involving heating decompression, then nearly isothermal decompression and nearly isobar cooling conditions shows that high temperature-low pressure metamorphism of the studied pelitic anatectic granulites of Kan Nack complex occurred possibly in extensional setting during the Indosinian orogeny of 260-240 Ma in age.

  19. Micro and Macroscale Drivers of Nutrient Concentrations in Urban Streams in South, Central and North America.

    PubMed

    Loiselle, Steven A; Gasparini Fernandes Cunha, Davi; Shupe, Scott; Valiente, Elsa; Rocha, Luciana; Heasley, Eleanore; Belmont, Patricia Pérez; Baruch, Avinoam

    Global metrics of land cover and land use provide a fundamental basis to examine the spatial variability of human-induced impacts on freshwater ecosystems. However, microscale processes and site specific conditions related to bank vegetation, pollution sources, adjacent land use and water uses can have important influences on ecosystem conditions, in particular in smaller tributary rivers. Compared to larger order rivers, these low-order streams and rivers are more numerous, yet often under-monitored. The present study explored the relationship of nutrient concentrations in 150 streams in 57 hydrological basins in South, Central and North America (Buenos Aires, Curitiba, São Paulo, Rio de Janeiro, Mexico City and Vancouver) with macroscale information available from global datasets and microscale data acquired by trained citizen scientists. Average sub-basin phosphate (P-PO4) concentrations were found to be well correlated with sub-basin attributes on both macro and microscales, while the relationships between sub-basin attributes and nitrate (N-NO3) concentrations were limited. A phosphate threshold for eutrophic conditions (>0.1 mg L-1 P-PO4) was exceeded in basins where microscale point source discharge points (eg. residential, industrial, urban/road) were identified in more than 86% of stream reaches monitored by citizen scientists. The presence of bankside vegetation covaried (rho = -0.53) with lower phosphate concentrations in the ecosystems studied. Macroscale information on nutrient loading allowed for a strong separation between basins with and without eutrophic conditions. Most importantly, the combination of macroscale and microscale information acquired increased our ability to explain sub-basin variability of P-PO4 concentrations. The identification of microscale point sources and bank vegetation conditions by citizen scientists provided important information that local authorities could use to improve their management of lower order river ecosystems.

  20. First LiDAR images of the Alpine Fault, central South Island, New Zealand

    NASA Astrophysics Data System (ADS)

    Langridge, R. M.; Toy, V. G.; Barth, N.; de Pascale, G. P.; Sutherland, R.; Farrier, T.

    2010-12-01

    In central South Island, New Zealand, the dextral-reverse Alpine fault forms the principal component of the Australia-Pacific plate boundary. The fault typically accommodates slip rates of the order of ~27-29 mm/yr (dextral) and up to 6-11 mm/yr (reverse), mostly uplifting Pacific plate rocks that form the Southern Alps. However, the associated high relief, rapid uplift and erosion and high rainfall and accompanying dense temperate rainforest along the western side of the island has typically hampered geological efforts to better understand the neotectonics of the Alpine fault. LiDAR data have been acquired over a 34 km stretch of the fault between Whataroa in the northeast and Franz Josef in the southwest to test the viability of this technique under dense vegetation and in steep, dissected terrain. LiDAR has been collected from a fixed wing base (1300m above ground level) at a frequency of 70k Hz, with 33.5 Hz scan frequency and a 39° field of view. We employed a strategy of flying a dense pattern of 6 flight lines across a swath width of 1.3 km. This creates areas of both single and double overlap coverage that have allowed for accurate landscape models to be created. Results show that this strategy has provided an optimum level of forest penetration and ground returns. Initial results show remarkable level of detail in DEM’s of the landscape along the Alpine fault. Examples of results presented here include: Franz Josef, where the fault traverses the township; and Gaunt Creek, where a Deep Fault Drilling Project will be sited in early 2011.

  1. Spring-migration ecology of Northern Pintails in south-central Nebraska

    USGS Publications Warehouse

    Pearse, A.T.; Krapu, G.L.; Cox, R.R.; Davis, B.E.

    2011-01-01

    Spring-migration ecology of staging Northern Pintails, Anas acuta, was investigated in south-central Nebraska, USA. Habitat associations, local movements, settling patterns, arrival dates, residency times and survival were estimated from 71 radiomarked pintails during spring 2001, 2003 and 2004, and diet determined from 130 females collected during spring 1998 and 1999. Seventy-two percent of pintail diurnal locations were in palustrine wetlands, 7% in riverine wetlands, 3% in lacustrine wetlands, 6% in municipal sewage lagoons and irrigation reuse pits and 10.5% in croplands. Emergent wetlands with hemi-marsh conditions were used diurnally more often than wetlands with either open or closed vegetation structures. Evening foraging flights averaged 4.3 km (SE = 0.6) and 72% were to cornfields. In accord with these findings, 87% of 93 pintails collected during spring 1998 and 1999 returning to evening roosts consumed corn, which represented 84% dry mass of all foods. Pintails collected on non-cropped wetlands ingested invertebrates and seeds from wetland plants more frequently than birds returning to roost. Radiomarked pintails arrived in Nebraska on 7 March 2003 and 18 February 2004; average arrival date was six days earlier during 2004 compared to 2003. Residency time for individuals varied greatly (1-40 days) yet yearly means were similar and averaged 9.5 days within the region. No mortality was detected for 71 birds monitored over 829 exposure days. Conservation planners linking population dynamics and habitat conditions at spring-staging areas need to focus on pintail body condition during spring and its connection with reproductive success and survival during the breeding season.

  2. Quality of ground water in southeastern and south-central Washington, 1982

    USGS Publications Warehouse

    Turney, G.L.

    1986-01-01

    In 1982 groundwater was sampled at over 100 sites in the southeastern-south central region of Washington and analyzed for pH, specific conductance, and concentrations of fecal-coliform bacteria, major dissolved irons, and dissolved iron, manganese, and nitrate. Twenty percent of the samples were analyzed for concentrations of dissolved aluminum, arsenic, barium, cadmium, chromium, cooper, lead, mercury, selenium, silver, and zinc. The predominant water type was calcium bicarbonate. Some sodium bicarbonate water was found in samples from the Lower Yakima, Horse Heaven Hills, and Walla Walla-Tucannon subregions. Dissolved solids concentrations were typically less than 500 mg/L (milligrams per liter). Median iron and manganese concentrations were less than 20 micrograms/L except in the Palouse subregion, where the median concentration of iron was 200 micrograms/L and the median concentrations of manganese was 45 micrograms/L. Generally, trace-metal concentrations were also less than 10 micrograms/L except for barium, copper, and zinc. Nitrate concentrations were less than 1.0 mg/L in waters from half the wells sampled. Concentrations greater than 5.0 mg/L were found in areas of the Lower Yakima, Walla Walla-Tucannon and Hanford subregions. No fecal-coliform bacteria were detected. U.S. Environmental Protection Agency drinking water regulation limits were generally not exceeded, except for occasional high concentrations of nitrate or dissolved solids. The historical data for the region were evaluated for these same constituents. Quantitative differences were found, but the historical and 1982 data led to similar qualitative conclusions. (USGS)

  3. Structural Model of the Basement in the Central Savannah River Area, South Carolina and Georgia

    SciTech Connect

    Stephenson, D.; Stieve, A.

    1992-03-01

    Interpretation of several generations of seismic reflection data and potential field data suggests the presence of several crustal blocks within the basement beneath the Coastal Plain in the Central Savannah River Area (CSRA). The seismic reflection and refraction data include a grid of profiles that capture shallow and deep reflection events and traverse the Savannah River Site and vicinity. Potential field data includes aeromagnetic, ground magnetic surveys, reconnaissance and detailed gravity surveys. Subsu