Diverse primitive magmas in the Cascade arc, Northern Oregon and Southern Washington
R. M. Conrey, D. R. Sherrod, P. R. Hooper, D. A. Swanson
1997, Canadian Mineralogist (35) 367-396
Bulk-rock major- and trace-element composition, petrography and mineral compositions are presented for a diverse suite of 22 primitive mafic lavas in the Cascade Range of northern Oregon and southern Washington. With the exception of an early Western Cascade basalt, all the rocks are younger than 7 Ma. Intensive parameters [F(H2O),...
The Bishop Tuff: New insights from eruptive stratigraphy
C. J. N. Wilson, W. Hildreth
1997, Journal of Geology (105) 407-439
The 0.76 Ma Bishop Tuff, from Long Valley caldera in eastern California, consists of a widespread fall deposit and voluminous partly welded ignimbrite. The fall deposit (F), exposed over an easterly sector below and adjacent to the ignimbrite, is divided into nine units (F1‐F9), with no significant time breaks, except...
Cabauw experimental results from the Project for Intercomparison of Land-Surface Parameterization Schemes
T.H. Chen, A. Henderson-Sellers, P. C. D. Milly, A.J. Pitman, A.C.M. Beljaars, J. Polcher, F. Abramopoulos, A. Boone, S. Chang, F. Chen, Y. Dai, C.E. Desborough, R.E. Dickinson, L. Dumenil, M. Ek, J.R. Garratt, N. Gedney, Y.M. Gusev, J. Kim, R. Koster, E.A. Kowalczyk, K. Laval, J. Lean, D. Lettenmaier, X. Liang, Jean-Francois Mahfouf, H.-T. Mengelkamp, Ken Mitchell, O.N. Nasonova, J. Noilhan, A. Robock, C. Rosenzweig, J. Schaake, C.A. Schlosser, J.-P. Schulz, Y. Shao, A.B. Shmakin, D.L. Verseghy, P. Wetzel, E.F. Wood, Y. Xue, Z.-L. Yang, Q. Zeng
1997, Journal of Climate (10) 1194-1215
In the Project for Intercomparison of Land-Surface Parameterization Schemes phase 2a experiment, meteorological data for the year 1987 from Cabauw, the Netherlands, were used as inputs to 23 land-surface flux schemes designed for use in climate and weather models. Schemes were evaluated by comparing their outputs with long-term measurements of...
Climatic controls of western U.S. glaciers at the last glacial maximum
S. W. Hostetler, P.U. Clark
1997, Quaternary Science Reviews (16) 505-511
We use a nested atmospheric modeling strategy to simulate precipitation and temperature of the western United States 18,000 years ago (18 ka). The high resolution of the nested model allows us to isolate the regional structure of summer temperature and winter precipitation that is crucial to determination of the net...
Controls on accretion of flysch and melange belts at convergent margins: Evidence from the Chugach Bay thrust and Iceworm melange, Chugach accretionary wedge, Alaska
Timothy M. Kusky, Dwight Bradley, Peter J. Haeussler, Susan M. Karl
1997, Tectonics (16) 855-878
Controls on accretion of flysch and mélange terranes at convergent margins are poorly understood. Southern Alaska's Chugach terrane forms the outboard accretionary margin of the Wrangellia composite terrane, and consists of two major lithotectonic units, including Triassic-Cretaceous mélange of the McHugh Complex and Late Cretaceous flysch of the Valdez Group....
222Rn transport in a fractured crystalline rock aquifer: Results from numerical simulations
P. F. Folger, E. Poeter, R. B. Wanty, W. Day, D. Frishman
1997, Journal of Hydrology (195) 45-77
Dissolved 222Rn concentrations in ground water from a small wellfield underlain by fractured Middle Proterozoic Pikes Peak Granite southwest of Denver, Colorado range from 124 to 840 kBq m-3 (3360-22700 pCi L-1). Numerical simulations of flow and transport between two wells show that differences in equivalent hydraulic aperture of transmissive...
Estimating the diminution of shear-wave amplitude with distance: Application to the Los Angeles, California, urban area
S. C. Harmsen
1997, Bulletin of the Seismological Society of America (87) 888-903
The rate of decay with distance of shear-wave amplitude, computed from 20-sec S-wave spectra, is determined from TERRAscope records of small earthquakes in the greater Los Angeles area. Piecewise log-linear interpolation functions and traditional diminution functions are used to fit spectral decay to a...
Watershed responses to climate change at Glacier National Park
D.B. Fagre, P.L. Comanor, J.D. White, F. Richard Hauer, S. W. Running
1997, Journal of the American Water Resources Association (33) 755-765
We have developed an approach which examines ecosystem function and the potential effects of climatic shifts. The Lake McDonald watershed of Glacier National Park was the focus for two linked research activities: acquisition of baseline data on hydrologic, chemical and aquatic organism attributes that characterize this pristine northern rocky mountain...
Roadblocks on the kill curve: Testing the Raup hypothesis
C. W. Poag
1997, Palaios (12) 582-590
The documented presence of two large (~100-km diameter), possibly coeval impact craters of late Eocene age, requires modification of the impact-kill curve proposed by David M. Raup. Though the estimated meteorite size for each crater alone is large enough to have produced considerable global environmental stress, no horizons of mass...
Supercritical fluid carbon dioxide extraction and liquid chromatographic separation with electrochemical detection of methylmercury from biological samples
N.S. Simon
1997, International Journal of Environmental Analytical Chemistry (68) 313-330
Using the coupled methods presented in this paper, methylmercury can be accurately and rapidly extracted from biological samples by modified supercritical fluid carbon dioxide and quantitated using liquid chromatography with reductive electrochemical detection. Supercritical fluid carbon dioxide modified with methanol effectively extracts underivatized methylmercury from certified reference materials Dorm-1 (dogfish...
Viscoelastic coupling model of the San Andreas fault along the Big Bend, southern California
J.C. Savage, M. Lisowski
1997, Journal of Geophysical Research B: Solid Earth (103) 7281-7292
The big bend segment of the San Andreas fault is the 300-km-long segment in southern California that strikes about N65°W, roughly 25° counterclockwise from the local tangent to the small circle about the Pacific-North America pole of rotation. The broad distribution of deformation of trilateration networks along this segment implies...
Surfactant-enhanced remediation of a trichloroethene-contaminated aquifer. 1. Transport of triton X-100
J. A. Smith, D. Sahoo, H.M. Mclellan, T.E. Imbrigiotta
1997, Environmental Science & Technology (31) 3565-3572
Transport of a nonionic surfactant (Triton X-100) at aqueous concentrations less than 400 mg/L through a trichloroethene-contaminated sand-and-gravel aquifer at Picatinny Arsenal, NJ, has been studied through a series of laboratory and field experiments. In the laboratory, batch and column experiments were conducted to quantify the rate and amount of...
Complexities of plinian fall deposition at vent: An example from the 1912 Novarupta eruption (Alaska)
J. Fierstein, Bruce F. Houghton, C. J. N. Wilson, W. Hildreth
1997, Journal of Volcanology and Geothermal Research (76) 215-227
An extremely proximal ejecta ring, with exposures to within 100 m of vent, was deposited during later-stage plinian fall activity during the 1912 Novarupta eruption in Alaska. One bed in the ejecta ring (bed S) contains predominantly andesitic clasts which serve to delineate the striking contrast in thinning rates along...
Transient triggering of near and distant earthquakes
J. Gomberg, M.L. Blanpied, N.M. Beeler
1997, Bulletin of the Seismological Society of America (87) 294-309
We demonstrate qualitatively that frictional instability theory provides a context for understanding how earthquakes may be triggered by transient loads associated with seismic waves from near and distance earthquakes. We assume that earthquake triggering is a stick-slip process and test two hypotheses about the effect of transients on the timing...
Deep well injection of brine from Paradox Valley, Colorado: Potential major precipitation problems remediated by nanofiltration
Yousif K. Kharaka, Gil Ambats, James J. Thordsen, Roy A. Davis
1997, Water Resources Research (33) 1013-1020
Groundwater brine seepage into the Dolores River in Paradox Valley, Colorado, increases the dissolved solids load of the Colorado River annually by ∼2.0 × 108 kg. To abate this natural contamination, the Bureau of Reclamation plans to pump ∼3540 m3/d of brine from 12 shallow wells located along the Dolores River....
Late Paleozoic crustal history of central coastal Queensland interpreted from geochemistry of Mesozoic plutons: The effects of continental rifting
C. M. Allen, J. L. Wooden, B. W. Chappell
1997, LITHOS (42) 67-88
The eastern margin of Australia is understood to be the result of continental rifting during the Cretaceous and Tertiary. Consistent with this model, Cretaceous igneous rocks (granites to basalts) in a continental marginal setting near Bowen, Queensland are isotonically retarded, having isotopic ratios similar to those of most island arcs...
An empirical comparison of stock identification techniques applied to striped bass
John R. Waldman, R. Anne Richards, W. Bane Schill, Isaac Wirgin, Mary C. Fabrizio
1997, Transactions of the American Fisheries Society (126) 369-385
Managers of migratory striped bass stocks that mix along the Atlantic coast of the USA require periodic estimates of the relative contributions of the individual stocks to coastal mixed- stock fisheries; however, to date, a standard approach has not been adopted. We compared the performances of alternative stock identification...
Subsidence of ash-flow calderas: Relation to caldera size and magma-chamber geometry
P. W. Lipman
1997, Bulletin of Volcanology (59) 198-218
Diverse subsidence geometries and collapse processes for ash-flow calderas are inferred to reflect varying sizes, roof geometries, and depths of the source magma chambers, in combination with prior volcanic and regional tectonic influences. Based largely on a review of features at eroded pre-Quaternary calderas, a continuum of geometries and subsidence...
Relationships between salt marsh loss and dredged canals in three Louisiana Estuaries
A.S. Bass, R.E. Turner
1997, Journal of Coastal Research (13) 895-903
Coastal land loss rates were quantified for 27 salt marshes in three estuaries of the Louisiana Mississippi Deltaic plain: Barataria, Terrebonne and St. Bernard. The sites ranged from 23 ha to 908 ha and the total area of all sites was 6,367 ha. Two methods were used to calculate open...
Temperature effects on stocks and stability of a phytoplankton-zooplankton model and the dependence on light and nutrients
J. Norberg, D.L. DeAngelis
1997, Ecological Modelling (95) 75-86
A model of a closed phytoplankton—zooplankton ecosystem was analyzed for effects of temperature on stocks and stability and the dependence of these effects on light and total nutrient concentration of the system. An analysis of the steady state equations showed that the effect of temperature on zooplankton and POM biomass...
Continents as lithological icebergs: The importance of buoyant lithospheric roots
D.H. Abbott, R. Drury, Walter D. Mooney
1997, Earth and Planetary Science Letters (149) 15-27
An understanding of the formation of new continental crust provides an important guide to locating the oldest terrestrial rocks and minerals. We evaluated the crustal thicknesses of the thinnest stable continental crust and of an unsubductable oceanic plateau and used the...
Using δ87Sr values to identify sources of salinity to a freshwater aquifer, Greater Aneth Oil Field, Utah, USA
D. L. Naftz, Z. E. Peterman, L.E. Spangler
1997, Chemical Geology (141) 195-209
Salinity increases in water from the freshwater Navajo aquifer in the Aneth area have been documented in recent years. Previous studies during the 1980s in the Aneth area suggested that brines associated with oil production and their subsequent re-injection were the probable source of salinity in the Navajo aquifer. Differences...
Use of geochemical mass balance modelling to evaluate the role of weathering in determining stream chemistry in five mid-Atlantic watersheds on different lithologies
Anne K. O’Brien, Karen C. Rice, Owen P. Bricker, Margaret M. Kennedy, R. Todd Anderson
1997, Hydrological Processes (11) 719-744
The importance of mineral weathering was assessed and compared for five mid-Atlantic watersheds receiving similar atmospheric inputs but underlain by differing bedrock. Annual solute mass balances and volume-weighted mean solute concentrations were calculated for each watershed for each year of record. In addition, primary and secondary mineralogy were determined for...
Sedimentary phosphorus cycling and a phosphorus mass balance for the Green Bay (Lake Michigan) ecosystem
Klump J. Val, D.N. Edgington, P.E. Sager, Dale M. Robertson
1997, Canadian Journal of Fisheries and Aquatic Sciences (54) 10-26
The tributaries of Green Bay have long been recognized as major sources of phosphorus in the Lake Michigan basin. The status of Green Bay as a sink or source of phosphorus for Lake Michigan proper has been less well defined. The bay receives nearly 70% of its annual load of...
Geochemical mole-balance modeling with uncertain data
David L. Parkhurst
1997, Water Resources Research (33) 1957-1970
Geochemical mole-balance models are sets of chemical reactions that quantitatively account for changes in the chemical and isotopic composition of water along a flow path. A revised mole-balance formulation that includes an uncertainty term for each chemical and isotopic datum is derived. The revised formulation is comprised of mole-balance equations...
