Mineral and whole-rock compositions of seawater-dominated hydrothermal alteration at the Arctic volcanogenic massive sulfide prospect, Alaska
J.M. Schmidt
1988, Economic Geology (83) 822-842
The Arctic volcanogenic massive sulfide prospect, located in the Ambler mineral district of northwestern Alaska, includes three types of hydrothermally altered rocks overlying, underlying, and interlayered with semimassive sulfide mineralization. Hydrothermal alteration of wall rocks and deposition of sulfide and gangue minerals were contemporaneous with Late Devonian or Early Mississippian...
Age and petrology of alkalic postshield and rejuvenated-stage lava from Kauai, Hawaii
D.A. Clague, G. B. Dalrymple
1988, Contributions to Mineralogy and Petrology (99) 202-218
At the top of the Waimea Canyon Basalt on the island of Kauai, rare flows of alkalic postshield-stage hawaiite and mugearite overlie tholeiitic flows of the shield stage. These postshield-stage flows are 3.92 Ma and provide a younger limit for the age of the tholeiitic shield stage. The younger Koloa...
Analytical approach to calculation of response spectra from seismological models of ground motion
Erdal Safak
1988, Earthquake Engineering and Structural Dynamics (16) 121-134
An analytical approach to calculate response spectra from seismological models of ground motion is presented. Seismological models have three major advantages over empirical models: (1) they help in an understanding of the physics of earthquake mechanisms, (2) they can be used to predict ground motions for future earthquakes and (3)...
Seismic imaging of extended crust with emphasis on the western United States
J. McCarthy, G. A. Thompson
1988, Geological Society of America Bulletin (100) 1361-1374
Understanding of the crust has improved dramatically following the application of seismic reflection and refraction techniques to studies of the deep crust. This is particularly true in areas where the last tectonic event was extensional, such as the Basin and Range province of the western United States and much of...
Two-dimensional Lagrangian simulation of suspended sediment
David H. Schoellhamer
1988, Journal of Hydraulic Engineering (114) 1192-1209
A two‐dimensional laterally averaged model for suspended sediment transport in steady gradually varied flow that is based on the Lagrangian reference frame is presented. The layered Lagrangian transport model (LLTM) for suspended sediment performs laterally averaged Lagrangian calculations with steady or unsteady upstream boundary concentration. The elevations of nearly horizontal...
Aftershock patterns and main shock faulting
C. Mendoza, S.H. Hartzell
1988, Bulletin of the Seismological Society of America (78) 1438-1449
We have compared aftershock patterns following several moderate to large earthquakes with the corresponding distributions of coseismic slip obtained from previous analyses of the recorded strong ground motion and teleseismic waveforms. Well-located aftershock hypocenters are projected onto the main shock fault plane, and their positions are examined relative to the...
Detection of tannins in modern and fossil barks and in plant residues by high-resolution solid-state 13C nuclear magnetic resonance
M. A. Wilson, Patrick G. Hatcher
1988, Organic Geochemistry (12) 539-546
Bark samples isolated from brown coal deposits in Victoria, Australia, and buried wood from Rhizophora mangle have been studies by high-resolution solid-state nuclear magnetic resonance (NMR) techniques. Dipolar dephasing 13C NMR appears to be a useful method of detecting the presence of tannins in geochemical samples including barks, buried woods, peats and leaf...
Nationwide regression models for predicting urban runoff water quality at unmonitored sites
Gary D. Tasker, N. E. Driver
1988, Water Resources Bulletin (24) 1091-1101
Regression models are presented that can be used to estimate mean loads for chemical oxygen demand, suspended solids, dissolved solids, total nitrogen, total ammonia plus nitrogen, total phosphorous, dissolved phosphorous, total copper, total lead, and total zinc at unmonitored sites in urban areas. Explanatory variables include drainage area, imperviousness of...
Waveform modelling using locked-mode synthetic and differential seismograms: application to determination of the structure of Mexico
J.S. Gomberg, T. Guy Masters
1988, Geophysical Journal International (94) 193-218
We have developed algorithms for modelling seismic waveforms to constrain regional Earth structure. The seismogram is represented as a sum of locked-mode travelling waves in a layered medium. This representation is convenient as it allows us to model structures with slowly varying heterogeneity and to construct differential seismograms. Describes the...
Statistical methods for investigating quiescence and other temporal seismicity patterns
M.V. Matthews, P.A. Reasenberg
1988, Pure and Applied Geophysics PAGEOPH (126) 357-372
We propose a statistical model and a technique for objective recognition of one of the most commonly cited seismicity patterns:microearthquake quiescence. We use a Poisson process model for seismicity and define a process with quiescence as one with a particular type of piece-wise constant intensity function. From this model, we...
High-performance liquid-chromatographic separation of subcomponents of antimycin-A
S. L. Abidi
1988, Journal of Chromatography (447) 65-79
Using a reversed-phase high-performance liquid chromatographic (HPLC) technique, a mixture of antimycins A was separated into eight hitherto unreported subcomponents, A1a, A1b, A2a, A2b, A3a, A3b, A4a, and A4b. Although a base-line resolution of the known four major antimycins A1, A2, A3, and A4 was readily achieved with mobile phases containing...
Semianalytical computation of path lines for finite-difference models
D.W. Pollock
1988, Ground Water (26) 743-750
A semianalytical particle tracking method was developed for use with velocities generated from block centered finite-difference ground-water flow models. The method is based on the assumption that each directional velocity component varies linearly within a grid cell in its own coordinate directions. This assumption allows...
Absence of strain accumulation in the Shumagin seismic gap, Alaska, 1980-1987
M. Lisowski, J.C. Savage, W.H. Prescott, W.K. Gross
1988, Journal of Geophysical Research Solid Earth (93) 7909-7922
Measurements of the deformation of a trilateration network in the Shumagin seismic gap in the interval 1980–1987 failed to detect any significant strain accumulation (observed extension rate in the direction of plate convergence 0.00±0.03 μstrain/yr). Dislocation models of the subduction process and measurements at a comparable network at a known...
Seismic stratigraphy of the Mississippi-Alabama shelf and upper continental slope
J. L. Kindinger
1988, Marine Geology (83) 79-94
The Mississippi-Alabama shelf and upper continental slope contain relatively thin Upper Pleistocene and Holocene deposits. Five stages of shelf evolution can be identified from the early Wisconsinan to present. The stages were controlled by glacioeustatic or relative sea-level changes and are...
The response of creeping parts of the San Andreas fault to earthquakes on nearby faults: Two examples
R.W. Simpson, S.S. Schulz, L.D. Dietz, Robert O. Burford
1988, Pure and Applied Geophysics PAGEOPH (126) 665-685
Rates of shallow slip on creeping sections of the San Andreas fault have been perturbed on a number of occasions by earthquakes occurring on nearby faults. One example of such perturbations occurred during the 26 January 1986 magnitude 5.3 Tres Pinos earthquake located about 10 km southeast of Hollister, California....
The origin of Chubutolithes Ihering, ichnofossils from the Eocene and Oligocene of Chubut Province, Argentina.
T.M. Brown, B.C. Ratcliffe
1988, Journal of Paleontology (62) 163-167
The distinctive trace fossil Chubutolithes gaimanensis n. ichnosp. occurs in Casamayoran (early Eocene) and Colhuéhaupian (late Oligocene) alluvial rocks of the Sarmiento Formation in eastern Chubut Province, Argentina. Though known for nearly 70 years, its origin has remained obscure. Examination of new specimens and comparisons with modern analogs...
Assimilation of granite by basaltic magma at Burnt Lava flow, Medicine Lake volcano, northern California: Decoupling of heat and mass transfer
T.L. Grove, R.J. Kinzler, M. B. Baker, J.M. Donnelly-Nolan, C.E. Lesher
1988, Contributions to Mineralogy and Petrology (99) 320-343
At Medicine Lake volcano, California, andesite of the Holocene Burnt Lava flow has been produced by fractional crystallization of parental high alumina basalt (HAB) accompanied by assimilation of granitic crustal material. Burnt Lava contains inclusions of quenched HAB liquid, a potential parent magma of the andesite, highly melted granitic crustal...
Variation of depth to the brittle-ductile transition due to cooling of a midcrustal intrusion
M. E. Gettings
1988, Geophysical Research Letters (15) 213-216
The depth to the brittle-ductile transition in the crust is often defined by the intersection of a shear resistance relation in the brittle upper crust that increases linearly with depth and a power law relation for ductile flow in the lower crust that depends strongly on...
Contrasting serpentinization processes in the eastern Central Alps
D.J.M. Burkhard, J. R. O’Neil
1988, Contributions to Mineralogy and Petrology (99) 498-506
Stable isotope compositions have been determined for serpentinites from between Davos (Arosa-Platta nappe, Switzerland) and the Valmalenco (Italy). ??D and ??18O values (-120 to -60 and 6-10???, respectively) in the Arosa-Platta nappe indicate that serpentinization took place on the continent at relatively low temperatures in the presence of limited amounts...
Earthquakes, July-August 1988
W. J. Person
1988, Earthquakes & Volcanoes (USGS) (20) 234-237
Major earthquakes (7.0-7.9) struck the Burma-India border on August 6 and the Solomon Islands on August 10. The most devastating earthquake during this reporting period was a magnitude 6.6 on the Nepal-India border on August 20. In the United States, there were no casualties from earthquakes but moderate earthquakes (5.0-5.9) were...
Comprehensive method of characteristics models for flow simulation
Chintu Lai
1988, Journal of Hydraulic Engineering (114) 1074-1097
The use of the specified time interval (STI) numerical schemes has been popular in applying the method of characteristics (MOC) to unsteady open‐channel flow problems. Studies and analyses of several variants of the STI schemes have led to the derivation of a new scheme, referred to herein as the multimode...
Icebergs rework shelf sediments to 500 m off Antarctica
P. W. Barnes, R. Lien
1988, Geology (16) 1130-1133
Icebergs and sea ice rework the sediments of high-latitude shelves, producing modern diamicts (ice-keel turbates) unrelated to glacial proximity. Off Antarctica, sidescan sonar data indicate the presence of ice-gouge features formed by the physical interaction between ice keels and the sea bed. These...
Ocean plateau-seamount origin of basaltic rocks, Angayucham terrane, central Alaska
F. Barker, D. L. Jones, J. R. Budahn, P.J. Coney
1988, Journal of Geology (96) 368-374
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...
Areal variation in recharge to and discharge from the Floridan aquifer system in Florida
Walter R. Aucott
1988, Water-Resources Investigations Report 88-4057
This report is a revision and update of existing recharge maps of the Floridan aquifer system to include quantitative information derived from Regional Aquifer Systems Analysis models as well as other recent information and also includes information on discharge from the system. The report represents predevelopment conditions with inset map...
Partition of nonionic organic compounds in aquatic systems
James A. Smith, Patrick J. Witkowski, Cary T. Chiou
1988, Reviews of Environmental Contamination and Toxicology (103) 127-151
In aqueous systems, the distribution of many nonionic organic solutes in soil-sediment, aquatic organisms, and dissolved organic matter can be explained in terms of a partition model. The nonionic organic solute is distributed between water and different organic phases that behave as bulk solvents. Factors such as polarity, composition, and...
