Models of grades and tonnages of some lode tin deposits
W. D. Menzie, B.L. Reed, Donald A. Singer
1988, Book chapter, Geology of tin deposits in Asia and the Pacific
Descriptive and grade/tonnage models have recently been built for many types of deposits. Such models consist of descriptions of mineralogy, host rocks, ore textures, controls, alteration, geochemical signatures, age, and tectonic settings, together with statistical models of grades, tonnages, and contained metal of deposits of each type. The models...
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....
Geohydrology and mathematical simulation of the Pajaro Valley aquifer system, Santa Cruz and Monterey Counties, California
M. J. Johnson, C.J. Londquist, Julie Laudon, H. T. Mitten
1988, Water-Resources Investigations Report 87-4281
Groundwater development has resulted in lowered water levels and seawater intrusion in the Pajaro Valley, California. An investigation was undertaken to describe the geohydrology of the groundwater flow system and to evaluate the response of the system to pumping stresses by using a mathematical model. The aquifer system consists of...
Retardations in fault creep rates before local moderate earthquakes along the San Andreas fault system, central California
Robert O. Burford
1988, Pure and Applied Geophysics PAGEOPH (126) 499-529
Records of shallow aseismic slip (fault creep) obtained along parts of the San Andreas and Calaveras faults in central California demonstrate that significant changes in creep rates often have been associated with local moderate earthquakes. An immediate postearthquake increase followed by gradual, long-term decay back to a previous background rate...
Molecular composition and mobility of torbanite precursors: Implications for the structure of coal
M. A. Wilson, B.D. Batts, Patrick G. Hatcher
1988, Energy & Fuels (2) 668-672
Coorongite, a torbanite precursor found in South Australia, and algal residues derived from Botryococcus braunii and other algae have been examined by solid-state 13C NMR techniques. The majority of carbon in these materials is present as (CH2)n. However, variable-temperature studies show that a considerable proportion of the alkyl chains have...
Use of the truncated shifted Pareto distribution in assessing size distribution of oil and gas fields
J.C. Houghton
1988, Mathematical Geology (20) 907-937
The truncated shifted Pareto (TSP) distribution, a variant of the two-parameter Pareto distribution, in which one parameter is added to shift the distribution right and left and the right-hand side is truncated, is used to model size distributions of oil and gas fields for resource assessment. Assumptions about limits to...
Crustal contributions to arc magmatism in the Andes of Central Chile
W. Hildreth, S. Moorbath
1988, Contributions to Mineralogy and Petrology (98) 455-489
Fifteen andesite-dacite stratovolcanoes on the volcanic front of a single segment of the Andean arc show along-arc changes in isotopic and elemental ratios that demonstrate large crustal contributions to magma genesis. All 15 centers lie 90 km above the Benioff zone and 280??20 km from the trench axis. Rate and...
On low-frequency errors of uniformly modulated filtered white-noise models for ground motions
Erdal Safak, David M. Boore
1988, Earthquake Engineering and Structural Dynamics (16) 381-388
Low-frequency errors of a commonly used non-stationary stochastic model (uniformly modulated filtered white-noise model) for earthquake ground motions are investigated. It is shown both analytically and by numerical simulation that uniformly modulated filter white-noise-type models systematically overestimate the spectral response for periods longer than the effective duration of the earthquake,...
Simulation and video animation of canal flushing created by a tide gate
David H. Schoellhamer
1988, Conference Paper
A tide-gate algorithm was added to a one-dimensional unsteady flow model that was calibrated, verified, and used to determine the locations of as many as five tide gates that would maximize flushing in two canal systems. Results from the flow model were used to run a branched Lagrangian transport model...
A conceptual framework for assessing cumulative impacts on the hydrology of nontidal wetlands
Thomas C. Winter
1988, Environmental Management (12) 605-620
Wetlands occur in geologic and hydrologic settings that enhance the accumulation or retention of water. Regional slope, local relief, and permeability of the land surface are major controls on the formation of wetlands by surface-water sources. However, these landscape features also have significant control over groundwater flow systems, which commonly...
Liquid-vapor relations in the critical region of the system NaCl-H2O from 380 to 415°C: A refined determination of the critical point and two-phase boundary of seawater
James L. Bischoff, Robert J. Rosenbauer
1988, Geochimica et Cosmochimica Acta (52) 2121-2126
Pressure-temperature-composition (P-T-x) relations for coexisting vapor and liquid phases in the system NaCl-H2O were determined experimentally in the critical region from 380 to 415°C. The results provide much improved control on the P-T-x critical line in this region. The critical point of seawater (3.2 wt% NaCl solution), which is bracketed in the...
Pyrolysis g.c.-m.s. of a series of degraded woods and coalified logs that increase in rank from peat to subbituminous coal
Patrick G. Hatcher, H. E. Lerch III, R. K. Kotra, T.V. Verheyen
1988, Fuel (67) 1069-1075
Xylem tissue from degraded wood and coalified logs or stems was examined by pyrolysis g.c.-m.s. to improve understanding of the coalification process. The pyrolysis data, when combined with solid-state 13C n.m.r. data for the same samples, show several stages of evolution during coalification. The first stage, microbial degradation in peat, involves...
A late Wisconsinan marine incursion into Cape Cod Bay, Massachusetts
R. N. Oldale
1988, Quaternary Research (30) 237-250
Reinterpretation of seismic-reflection data from Cape Cod Bay has produced a revised late Wisconsinan history. Acoustically laminated deposits, originally inferred to be glaciolacustrine, are shown to be glaciomarine by tracing them to glaciomarine mud in Stellwagen Basin, north of Cape Cod Bay. A late Wisconsinan marine deposit of nonglacial origin...
Distribution of selenium in soils of agricultural fields, western San Joaquin Valley, California
Roger Fujii, S. J. Deverel, D. B. Hatfield
1988, Soil Science Society of America Journal (52) 1274-1283
Soils from three agricultural fields in the Panoche Creek alluvial fan area in the western San Joaquin Valley, California, were analyzed for soluble, adsorbed, and total concentrations of selenium (Se) to assess the distribution and forms of Se in relation to the leaching of Se from soils. This assessment is...
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...
Groundwater flow and transport modeling
Leonard F. Konikow, J.W. Mercer
1988, Journal of Hydrology (100) 379-409
Deterministic, distributed-parameter, numerical simulation models for analyzing groundwater flow and transport problems have come to be used almost routinely during the past decade. A review of the theoretical basis and practical use of groundwater flow and solute transport models is used to illustrate...
A note on the recent natural gradient tracer test at the Borden Site
R.L. Naff, T.-C. Jim Yeh, M.W. Kemblowski
1988, Water Resources Research (24) 2099-2103
The variance in particle position, a measure of dispersion, is reviewed in the context of certain models of flow in random porous media. Asymptotic results for a highly stratified medium and an isotropic medium are particularly highlighted. Results of the natural gradient tracer test at the Borden site are reviewed...
Regression estimates for topological‐hydrograph input
Michael R. Karlinger, D. Phillip Guertin, Brent M. Troutman
1988, Journal of Water Resources Planning and Management (114) 446-456
Physiographic, hydrologic, and rainfall data from 18 small drainage basins in semiarid, central Wyoming were used to calibrate topological, unit‐hydrograph models for celerity, the average rate of travel of a flood wave through the basin. The data set consisted of basin characteristics and hydrologic data for the 18 basins and...
The development of the continental margin of eastern North America-conjugate continental margin to West Africa
William P. Dillon, J. S. Schlee, Kim D. Klitgord
1988, Journal of African Earth Sciences (7) 361-367
The continental margin of eastern North America was initiated when West Africa and North America were rifted apart in Triassic-Early Jurassic time. Cooling of the crust and its thinning by rifting and extension caused subsidence. Variation in amounts of subsidence led to formation of five basins....
Rapid dune changes associated with overwash processes on the deltaic coast of South Louisiana
W. Ritchie, S. Penland
1988, Marine Geology (81) 97-122
The Caminada-Moreau barrier headland of South Louisiana is a low-profile beach and dune coastline that is transgressing rapidly over the surfaces of the abandoned Lafourche delta complex. With the passage of cold fronts (10–30 times per year) and hurricanes (once...
The plumbotectonic model for Pb isotopic systematics among major terrestrial reservoirs: A case for bi-directional transport
R. E. Zartman, S.M. Haines
1988, Geochimica et Cosmochimica Acta (52) 1327-1339
Version IV of plumbotectonics expands and refines the original model of Doe and Zartman (1979) and Zartman and Doe (1981) for explaining Pb (Sr, and Nd) isotopic systematics among major terrestrial reservoirs. A case for bi-directional transport among reservoirs is based on the observed isotopic compositions for different tectonic settings, and finds a rationale...
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...
Thermal modelling of stepwise anatexis in a thrust-thickened sialic crust
E-An Zen
1988, Transactions of the Royal Society of Edinburgh, Earth Sciences (79) 223-235
One-dimensional modelling of the thermal history of a sialic crust thickened by multiple overstack thrusting of upper crustal material shows that anatexis is likely. both the uplift rate and the length of the incubation period between end of tectonism and start of uplift are important controls on the amount and...
Climatological observations and predicted sublimation rates at Lake Hoare, Antarctica.
G.D. Clow, C.P. McKay, G.M. Simmons Jr., R.A. Wharton Jr.
1988, Journal of Climate (1) 715-728
In December 1985, an automated meteorological station was established at Lake Hoare in the dry valley region of Antarctica. Here, we report on the first year-round observations available for any site in Taylor Valley. This dataset augments the year-round data obtained at Lake Vanda (Wright Valley) by winter-over crews during...
On-line estimation of nonlinear physical systems
G. Christakos
1988, Mathematical Geology (20) 111-133
Recursive algorithms for estimating states of nonlinear physical systems are presented. Orthogonality properties are rediscovered and the associated polynomials are used to linearize state and observation models of the underlying random processes. This requires some key hypotheses regarding the structure of these processes, which may then take account of a...
