Morphology of sea-floor landslides on Horizon Guyot: application of steady-state geotechnical analysis
R. E. Kayen, W. C. Schwab, H.J. Lee, M.E. Torresan, J.R. Hein, P. J. Quinterno, L.A. Levin
1989, Deep Sea Research Part A, Oceanographic Research Papers (36) 1817-1839
Mass movement and erosion have been identified on the pelagic sediment cap of Horizon Guyot, a seamount in the Mid-Pacific Mountains. Trends in the size, shape and preservation of bedforms and sediment textural trends on the pelagic cap indicate that bottom-current-generated sediment transport direction is upslope. Slumping of the sediment...
Review of magnetic and electric field effects near active faults and volcanoes in the U.S.A.
M.J.S. Johnston
1989, Physics of the Earth and Planetary Interiors (57) 47-63
Synchronized measurements of geomagnetic field have been recorded along 800 km of the San Andreas fault and in the Long Valley caldera since 1974, and during eruptions on Mount St. Helens since 1980. For shorter periods of time, continuous measurements of geoelectric field measurements have been made on Mount St....
Early Proterozoic activity on Archean faults in the western Superior province - evidence from pseudotachylite
Z. E. Peterman, W. Day
1989, Geology (17) 1089-1092
Late Archean granitic plutons (∼2700 to 2665 Ma; U-Pb zircon) of the Superior structural province are cut by a variety of brittle discontinuities, including joints, fractures, and faults, the latter of which show evidence of cataclasis and meter to tens of meters displacements....
40Ar-39Ar dating of the Manson impact structure: A Cretaceous-Tertiary boundary crater candidate
Michael J. Kunk, G. A. Izett, R. A. Haugerud, J. F. Sutter
1989, Science (244) 1565-1568
The mineralogy of shocked mineral and lithic grains in the Cretaceous-Tertiary (K-T) boundary claystone worldwide is most consistent with a bolide impact on a continent. Both the concentrations and sizes of these shocked grains are greatest in the western interior of North America. These data suggest that the Manson impact...
Temporal and spatial patterns of phytoplankton production in Tomales Bay, California, U.S.A.
B.E. Cole
1989, Estuarine, Coastal and Shelf Science (28) 103-115
Primary productivity in the water column was measured 14 times between April 1985 and April 1986 at three sites in Tomales Bay, California, USA The conditions at these three stations encompassed the range of hydrographic conditions, phytoplankton biomass, phytoplankton community composition, and turbidity typical of this coastal embayment. Linear regression...
Organic markers as source discriminants and sediment transport indicators in south San Francisco Bay, California
F. D. Hostettler, J. B. Rapp, K.A. Kvenvolden, N L. Samuel
1989, Geochimica et Cosmochimica Acta (53) 1563-1576
Sediment samples from nearshore sites in south San Francisco Bay and from streams flowing into that section of the Bay have been characterized in terms of their content of biogenic and anthropogenic molecular marker compounds. The distributions, input sources, and applicability of these compounds in determining sediment movement are discussed....
A comparison of lead-isotope measurements on exploration-type samples using inductively coupled plasma and thermal ionization mass spectrometry
B.L. Gulson, A. L. Meier, S. E. Church, K.J. Mizon
1989, Journal of Geochemical Exploration (32) 311-313
Thermal ionization mass spectrometry (TI-MS) has long been the method of choice for Pb-isotope determinations. More recently, however, inductively coupled plasma mass spectrometry (ICP-MS) has been used to determine Pb-isotope ratios for mineral exploration. The ICP-MS technique, although not as precise...
Moderate-temperature zeolitic alteration in a cooling pyroclastic deposit
S. S. Levy, J. R. O’Neil
1989, Chemical Geology (76) 321-326
The locally zeolitized Topopah Spring Member of the Paintbrush Tuff (13 Myr.), Yucca Mountain, Nevada, U.S.A., is part of a thick sequence of zeolitized pyroclastic units. Most of the zeolitized units are nonwelded tuffs that were altered during low-temperature diagenesis, but the distribution and textural setting of zeolite (heulandite-clinoptilolite) and...
Spectral characteristics of chlorites and Mg‐serpentines using high‐resolution reflectance spectroscopy
T. V. V. King, Roger N. Clark
1989, Journal of Geophysical Research: Solid Earth (94) 13997-14008
The present laboratory study using high‐resolution reflectance spectroscopy (0.25–2.7 μm) focuses on two primary phyllosilicate groups, serpentines and chlorites. The results show that it is possible to spectrally distinguish between isochemical end‐members of the Mg‐rich serpentine group (chrysotile, antigorite, and lizardite) and to recognize spectral variations in chlorites as a...
Use of on-site high performance liquid chromatography to evaluate the magnitude and extent of organic contaminants in aquifers
D.F. Goerlitz, B.J. Franks
1989, Ground Water Monitoring Review (9) 122-129
Appraisal of ground water contaminated by organic substances raises problems of difficult sample collection and timely chemical analysis. High-performance liquid chromatography was evaluated for on-site determination of specific organic contaminants in ground water samples and was used at three study sites. Organic solutes were determined directly in water samples, with...
Plans for national flood frequency by microcomputer
M.E. Jennings, E.N. Cookmeyer
1989, Conference Paper
Work is underway on a planned microcomputer program that will include about 1500 prediction equations for 214 flood regions of the United States and Puerto Rico. The program will include calculation routines for rural and urban flood frequency and hydrograph characteristics and will have links to a detention-pond routing model....
Transformation of dilative and contractive landslide debris into debris flows-An example from Marin County, California
R. W. Fleming, S. D. Ellen, M.A. Algus
1989, Engineering Geology (27) 201-223
The severe rainstorm of January 3, 4 and 5, 1982, in the San Francisco Bay area, California, produced numerous landslides, many of which transformed into damaging debris flows. The process of transformation was studied in detail at one site where only...
Late Quaternary paleolimnology of Walker Lake, Nevada
Bradbury J. Platt, R. M. Forester, R.S. Thompson
1989, Journal of Paleolimnology (1) 249-267
Diatoms, crustaceans, and pollen from sediment cores, in conjunction with dated shoreline tufas provide evidence for lake level and environmental fluctuations of Walker Lake in the late Quaternary. Large and rapid changes of lake chemistry and level apparently resulted from variations in the course and discharge of the Walker River....
Igneous history of the Koyukuk terrane, western Alaska: Constraints on the origin, evolution, and ultimate collision of an accreted island arc terrane
S. E. Box, W. W. Patton Jr.
1989, Journal of Geophysical Research Solid Earth (94) 15843-15867
The Koyukuk terrane of western Alaska consists of volcanic, volcaniclastic, and plutonic rocks which range from Late Paleozoic to Early Cretaceous in age. The terrane crops out in a U-shaped belt which is roughly paralleled by outer belts of ultramafic rocks, oceanic plate basalts and cherts, and retrograded blueschist facies...
Significance of loessite in the Maroon Formation (Middle Pennsylvanian to Lower Permian), Eagle Basin, northwest Colorado
S. Y. Johnson
1989, Journal of Sedimentary Petrology (59) 782-791
Quaternary loess deposits are widespread on the earth's surface, yet pre-Quaternary loess deposits have rarely been reported. The Maroon Formation (Middle Pennsylvanian to Lower Permian) of the Eagle Basin, northwest Colorado, includes a siltstone-dominated facies interpreted as loessite (lithified loess) along its downwind...
Comparison of metasomatic reactions between a common CO2-rich vein fluid and diverse wall rocks: Intensive variables, mass transfers, and Au mineralization at Alleghany, California
J.K. Böhlke
1989, Economic Geology (84) 291-327
The gold deposits at Alleghany, California, are typical of many epigenetic gold-bearing hydrothermal vein systems in metamorphic terranes worldwide. Detailed analyses of alteration halos in serpentinite, mafic amphibolite, and granite wall rocks at Alleghany indicate that widely contrasting deposit types, ranging from fuchsite-carbonate schists to pyrite-albitites, resulted when different wall...
Monitoring and design of stormwater control basins
J.E. Veenhuis, J.H. Parrish, M.E. Jennings
1989, Conference Paper
The City of Austin, Texas, has played a pioneering role in the control of urban nonpoint source pollution by enacting watershed and stormwater ordinances, overseeing detailed monitoring programs, and improving design criteria for stormwater control methods. The effectiveness of the methods used in Austin, and perhaps in other areas of...
Experimental studies of compaction and dilatancy during frictional sliding on faults containing gouge
C.A. Morrow, J.D. Byerlee
1989, Journal of Structural Geology (11) 815-825
Transient strength changes are observed in fault gouge materials when the velocity of shearing is varied. A transient stress peak is produced when the strain rate in the gouge is suddenly increased, whereas a transient stress drop results from a sudden...
On numerical modeling of one-dimensional geothermal histories
R. A. Haugerud
1989, Computers & Geosciences (15) 825-836
Numerical models of one-dimensional geothermal histories are one way of understanding the relations between tectonics and transient thermal structure in the crust. Such models can be powerful tools for interpreting geochronologic and thermobarometric data. A flexible program to calculate these models on a microcomputer is available and examples of its...
The influence of formation material properties on the response of water levels in wells to Earth tides and atmospheric loading
S. Rojstaczer, D.C. Agnew
1989, Journal of Geophysical Research Solid Earth (94) 12403-12411
The water level in an open well can change in response to deformation of the surrounding material, either because of applied strains (tidal or tectonic) or surface loading by atmospheric pressure changes. Under conditions of no vertical fluid flow and negligible well bore storage (static-confined conditions), the sensitivities to these...
Direct evidence for the origin of low-18O silicic magmas: quenched samples of a magma chamber's partially-fused granitoid walls, Crater Lake, Oregon
Charles R. Bacon, Lanford H. Adami, Marvin A. Lanphere
1989, Earth and Planetary Science Letters (96) 199-208
Partially fused granitoid blocks were ejected in the climactic eruption of Mount Mazama, which was accompanied by collapse of Crater Lake caldera. Quartz, plagioclase, and glass in the granitoids have much lower δ18O values (−3.4 to +4.9‰) than any fresh lavas of Mount Mazama and the surrounding region (+5.8 to +7.0‰). Oxygen...
Potentiometric surface of the lower Cape Fear aquifer in the central coastal plain of North Carolina, December 1986
M. D. Winner Jr., William L. Lyke, Allen R. Brockman
1989, Water-Resources Investigations Report 87-4234
Water level measurements were made in four wells open to the lower Cape Fear aquifer at the end of 1986 to determine the configuration of its potentiometric surface over an area of approximately 4,100 sq mi. Because of the scarcity of data, five earlier measurements were also used to help...
A thrust-ridge paleodepositional model for the Upper Freeport coal bed and associated clastic facies, Upper Potomac coal field, Appalachian basin, U.S.A.
Edward S. Belt, P.C. Lyons
1989, International Journal of Coal Geology (12) 293-328
A blind-thrust-ridge model is proposed to explain the lack of coarse clastic material in the vast minable Upper Freeport coal bed (UF). This coal bed contains only fine elastic partings and is overlain by regionally extensive, closely spaced channel-belt deposits in...
Three-dimensional records of surface displacement on the Superstition Hills fault zone associated with the earthquakes of 24 November 1987
R. V. Sharp, J.L. Saxton
1989, Bulletin of the Seismological Society of America (79) 376-389
Seven quadrilaterals, constructed at broadly distributed points on surface breaks within the Superstition Hills fault zone, were repeatedly remeasured after the pair of 24 November 1987 earthquakes to monitor the growing surface displacement. Changes in the dimensions of the quadrilaterals are recalculated to right-lateral and extensional components at millimeter resolution,...
Field measurements of dry deposition to spruce foliage and petri dishes in the Black Forest, F.R.G.
J. B. Shanley
1989, Atmospheric Environment (23) 403-414
Dry deposition fluxes of Ca2+, Mg2+ , K+, Mn2+, Pb2+ and SO2−4 to spruce foliage and petri dishes were measured in two high-elevation sites ( > 900 m) in the southern Black Forest, F.R.G., during 12 periods (2–7 days, each) from mid-September to mid-November, 1983, In situ extraction of deposited material from small spruce branches...
