Fossil Scenedesmus (Chlorococcales) from the Raton Formation, Colorado and New Mexico, U.S.A.
Fleming R. Farley
1989, Review of Palaeobotany and Palynology (59) 1-6
Fossilized coenobia of the alga Scenedesmus (Chlorococcales) were recovered in palynomorph assemblages from a lower Paleocene mudstone in the Upper Cretaceous and Paleocene Raton Formation of Colorado and New Mexico. This is the first description of fossil Scenedesmus from Tertiary rocks. Two species, Scenedesmus tschudyi sp. nov. and Scenedesmus hanleyi...
Sea-floor drainage features of Cascadia Basin and the adjacent continental slope, northeast Pacific Ocean
M. A. Hampton, Herman A. Karl, Neil H. Kenyon
1989, Marine Geology (87) 249-272
Sea-floor drainage features of Cascadia Basin and the adjacent continental slope include canyons, primary fan valleys, deep-sea valleys, and remnant valley segments. Long-range sidescan sonographs and associated seismic-reflection profiles indicate that the canyons may originate along a mid-slope escarpment and grow...
Late cretaceous pelagic sediments, volcanic ASH and biotas from near the Louisville hotspot, Pacific Plate, paleolatitude ∼42°S
Peter F. Ballance, John A. Barron, Charles D. Blome, David Bukry, Peter A. Cawood, George Chaproniere, Robyn Frisch, Richard H. Herzer, Campbell S. Nelson, Paula Quinterno, Holly F. Ryan, David W. Scholl, Andrew J. Stevenson, David G. Tappin, Tracy L. Vallier
1989, Palaeogeography, Palaeoclimatology, Palaeoecology (71) 281-299
Dredging on the deep inner slope of the Tonga Trench, immediately north of the intersection between the Louisville Ridge hotspot chain and the trench, recovered some Late Cretaceous (Maestrichtian) slightly tuffaceous pelagic sediments. They are inferred to have been scraped off a recently subducted Late Cretaceous guyot of the Louisville...
Chloritization and associated alteration at the Jabiluka unconformity-type uranium deposit, Northern Territory, Australia
Constance J. Nutt
1989, Canadian Mineralogist (27 pt 1) 41-58
Jabiluka is the largest of four known uncomformity-type uranium deposits that are hosted by brecciated and altered metasedimentary rocks in the Pine Creek geosyncline, Northern Territory, Australia. The alteration zone at Jabiluka is dominated by chlorite, but also contains white mica, tourmaline and apatite; hematite is present, but only in...
Morphology and growth history of Delgada Fan: Implications for the Neogene evolution of Point Arena Basin and the Mendocino Triple Junction
D.E. Drake, D.A. Cacchione, J.V. Gardner, D. S. McCulloch, D. Masson
1989, Journal of Geophysical Research Solid Earth (94) 3139-3158
Long-range side scan (GLORIA) sonographs and seismic reflection data acquired during a survey of the western U.S. Exclusive Economic Zone in 1984, coupled with information from Deep Sea Drilling Project sites, provide new insights into the growth and evolution of the Delgada Fan. Construction of the fan commenced in the...
Surface faulting along the Superstition Hills fault zone and nearby faults associated with the earthquakes of 24 November 1987
R. V. Sharp
1989, Bulletin of the Seismological Society of America (79) 252-281
The M 6.2 Elmore Desert Ranch earthquake of 24 November 1987 was associated spatially and probably temporally with left-lateral surface rupture on many northeast-trending faults in and near the Superstition Hills in western Imperial Valley. Three curving discontinuous principal zones of rupture among these breaks extended northeastward from near the...
New evidence for polyphase metamorphism of glaucophane schist and eclogite exotic blocks in the Franciscan Complex, California and Oregon
Diane E. Moore, M.C. Blake Jr.
1989, Journal of Metamorphic Geology (7) 211-228
The early metamorphic history of high-grade exotic blocks in the Franciscan Complex may be more complicated than previously supposed. The different assemblages of high-grade glaucophane schists, eclogite, amphibolite and hornblende schist are commonly considered to have formed at the same time from essentially unmetamorphosed oceanic crust. However, new textural and...
A channel dynamics model for real-time flood forecasting
Anne B. Hoos, Antonis D. Koussis, Guy O. Beale
1989, Water Resources Research (25) 691-705
A new channel dynamics scheme (alternative system predictor in real time (ASPIRE)), designed specifically for real-time river flow forecasting, is introduced to reduce uncertainty in the forecast. ASPIRE is a storage routing model that limits the influence of catchment model forecast errors to the downstream station closest to the catchment....
Rates and processes of channel development and recovery following the 1980 eruption of Mount St. Helens, Washington
D. F. Meyer, H. A. Martinson
1989, Hydrological Sciences Journal (34) 115-127
Stream channel development in response to the eruption of Mount St. Helens on 18 May 1980, resulted in some of the largest sediment yields documented anywhere on earth. Development of new channels on the 2.7 km3 debris-avalanche deposit in the North Fork Toutle River caused net erosion of as much as...
Rupture process of the Ms 6.6 Superstition Hills, California, earthquake determined from strong-motion recordings: application of tomographic source inversion
Arthur D. Frankel, Leif Wennerberg
1989, Bulletin of the Seismological Society of America (79) 515-541
We analyze strong-motion recordings of the Ms 6.6 Superstition Hills earthquake to determine the timing, location, spatial extent, and rupture velocity of the subevents that produced the bulk of the high-frequency (0.5 to 4 Hz) seismic energy radiated by this shock. The earthquake can be characterized by three principal subevents,...
A high-resolution seismic reflection/refraction study of the Chugach-Peninsular terrane boundary, southern Alaska
T.M. Brocher, M. A. Fisher, E.L. Geist, N.I. Christensen
1989, Journal of Geophysical Research Solid Earth (94) 4441-4455
We present results from a high-resolution seismic refraction analysis of the shallow (approximately 2 km) crustal structure along the 107-km-long Trans-Alaska Crustal Transect Chugach reflection line in southern Alaska and a comparison with laboratory measurements of field samples. The refraction analysis includes the two-dimensional interpretation of several thousand first- and...
Paleomagnetism of the Oligocene Kalamazoo Tuff: implications for middle Tertiary extension in east central Nevada
J.T. Hagstrum, P. B. Gans
1989, Journal of Geophysical Research Solid Earth (94) 1827-1842
The Oligocene Kalamazoo Tuff (≃35 Ma) was sampled for paleomagnetic analysis across a 100-km-wide zone of highly extended crust in east central Nevada to estimate between-site vertical axis rotations and thus the relative importance of strike-slip faulting to the mechanism of extension. Subordinate sampling was also undertaken in a younger...
Upper Jurassic mafic magmatic rocks of the eastern Klamath Mountains, northern California: remnant of a volcanic arc built on young continental crust
M. Brouxel, H. Lapierre, J.-L. Zimmermann
1989, Geology (17) 273-276
Diabasic and gabbroic dikes intruding the lower Paleozoic Trinity Ophiolite in the Lovers Leap section, Klamath Mountains, California, display strong calc-alkalic petrological and geochemical features (occurrence of primary amphiboles, zoned plagioclase phenocrysts and biotite, low TiO2, high incompatible trace-element contents, and light rare...
Assessing the validity of the channel model of fracture aperture under field conditions
Allen M. Shapiro, James R. Nicholas
1989, Water Resources Research (25) 817-828
In recent investigations of fluid and solute movement in discrete fractures, spatial heterogeneity of the fracture aperture has been conceptualized as a series of noninterconnecting constant aperture flow paths, or channels. Two methods of estimating the distribution of the aperture sizes are presented using information from a single-hole pumping test...
Stress origins and earthquake potentials in Cascadia
W. Spence
1989, Journal of Geophysical Research Solid Earth (94) 3076-3088
Focal mechanism solutions for shallow earthquakes throughout the Cascadia plate system indicate that the primary regional stress is northerly compression, even though the Juan de Fuca plate generally is thought to be subducting N50°E. This compressional stress is pervasive throughout the Gorda-Juan de Fuca-Explorer plate system and much of the...
Whitings, a sedimentologic dilemma
E.A. Shinn, R.P. Steinen, B. H. Lidz, Peter K. Swart
1989, Journal of Sedimentary Petrology (59) 147-161
Whitings, drifting clouds of water, milky because of suspended carbonate, have been claimed to originate from either the action of bottom-feeding fish or direct precipitation of calcium carbonate. Five cruises during different seasons were made to the Great Bahama Bank to collect data...
Circular convection during subsurface injection of liquid waste, St. Petersburg, Florida
John J. Hickey
1989, Water Resources Research (25) 1481-1494
Injection of liquid waste into a highly transmissive, saltwater-bearing, fractured dolomite underlying the city of St. Petersburg, Florida, provided an opportunity to study density-dependent flow associated with two miscible and density-different liquids. The injection zone was 98 m thick with a radial hydraulic conductivity of 762 m/d and a vertical...
Singularity spectrum of intermittent seismic tremor at Kilauea Volcano, Hawaii
H. R. Shaw, B. Chouet
1989, Geophysical Research Letters (16) 195-198
Fractal singularity analysis (FSA) is used to study a 22-year record of deep seismic tremor (30–60 km depth) for regions below Kilauea Volcano on the assumption that magma transport and fracture can be treated as a system of coupled nonlinear oscillators. Tremor episodes range from 1...
Thermal stresses due to cooling of a viscoelastic oceanic lithosphere
R.P. Denlinger, W. Z. Savage
1989, Journal of Geophysical Research Solid Earth (94) 744-752
Theories based upon thermal contraction of cooling oceanic lithosphere provide a successful basis for correlating seafloor bathymetry and heat flow. The horizontal components of the contraction of the lithosphere as it cools potentially give rise to large thermal stresses. Current methods to calculate these stresses assume that on the time...
Influence of coupling of sorption and photosynthetic processes on trace element cycles in natural waters
C. C. Fuller, J.A. Davis
1989, Nature (340) 52-57
Chemical and biological processes have important roles in the transport and cycling of trace elements in natural waters, but their complex interactions are often not well understood. Trace-element concentrations may, for example, be controlled by adsorption-desorption reactions at mineral surfaces, with the equilibrium strongly influenced by pH. Variations in pH...
Physical and chemical characteristics of a metal-contaminated overbank deposit, west-central South Dakota, USA
D. C. Marron
1989, Earth Surface Processes and Landforms (14) 419-432
The deposit along the Belle Fourche River is typically up to 2 m thick and extends about 90 m away from the channel along the insides of meander bends. The sediments contain above-background levels of copper, iron, manganese, zinc, and particularly arsenic. An influx at high streamflow of uncontaminated sediment...
Interrelationships among hydrologic-budget components of a northern Wisconsin seepage lake and implications for acid-deposition modeling
Dennis A. Wentz, William J. Rose
1989, Archives of Environmental Contamination and Toxicology (18) 147-155
Components of the hydrologic budget for a northern Wisconsin seepage lake were analyzed by applying correlation and regression techniques to monthly data. Analyses for the 1981–83 water years revealed a statistically significant, direct relationship between storage change and precipitation-evaporation balance. Ground-water outflow was negatively correlated with ground-water inflow, and this...
A terracing operator for physical property mapping with potential field data
L. Cordell, A. E. McCafferty
1989, Geophysics (54) 621-634
The terracing operator works iteratively on gravity or magnetic data, using the sense of the measured field's local curvature, to produce a field comprised of uniform domains separated by abrupt domain boundaries. The result is crudely proportional to a physical-property function defined in one (profile case) or two (map case)...
Interaction of fine sediment with alluvial streambeds
Harvey E. Jobson, William P. Carey
1989, Water Resources Research (25) 135-140
More knowledge is needed about the physical processes that control the transport of fine sediment moving over an alluvial bed. The knowledge is needed to design rational sampling and monitoring programs that assess the transport and fate of toxic substances in surface waters because the toxics are often associated with...
Use of the variable gain settings on SPOT
P.S. Chavez Jr.
1989, Photogrammetric Engineering and Remote Sensing (55) 195-201
Often the brightness or digital number (DN) range of satellite image data is less than optimal and uses only a portion of the available values (0 to 255) because the range of reflectance values is small. Most imaging systems have been designed with only two gain settings, normal and high....
