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At least 1,585 records · Page 88Linked to original sources
USGS1983

THEMATIC MAPPER: DETAILED RADIOMETRIC AND GEOMETRIC CHARACTERISTICS.

The paper is in abstract form. It discusses those radiometric characteristics of the Landsat 4 Thematic Mapper (TM) that can be established without absolute calibration or spectral data. Subscenes of radiometrically raw data (B-data) were examined on an individual detector basis; areas of uniform radiance were used to characterize subtle radiometric differences and noise problems. The effective resolution in radiance is degraded by about a factor of two by irregular width of the digital levels. Several detectors have a change of gain with a period of several scans, the largest effect is about 4%. The geometric fidelity of the GSFC filmwriter used for Thematic Mapper (TM) images was assessed by measurement with accuracy better than three micrometers of a test grid.

Conference Paper↗
USGS1983

LITHOLOGIC MAPPING USING LANDSAT THEMATIC MAPPER DATA.

The paper is in abstract form. It discusses the Landsat-4 Thematic Mapper (TM), with its new near infrared bands centered at 1. 65 mu m and 2. 20 mu m and spatial resolution of 30 m, which has been used to distinguish rocks containing minerals having ferric-iron absorption bands in the visible and near-infrared and Al-O and CO//3 absorption bands in the 2. 1-2. 4 mu m regions. On the basis of characteristic absorption bands, digitally processed TM data were used to differentiate vegetated from non-vegetated areas, limonitic from nonlimonitic rocks, rocks containing minerals having absorption bands in the near-infrared region from rocks lacking the infrared absorption bands. Specific minerals were detected in both the humid eastern and semi-arid western United States. The absorption bands in the near-infrared region were used to detect kaolinite in open-pit exposures of a kaolin mining district near Macon, Georgia; calcium carbonate in the beach sands along the east coast of Florida; and kaolinite, alunite, jarosite, sericite and gypsum in natural exposures near Boulder City, Nevada.

Conference Paper↗
USGS1983

SOME NEW PROCESSING TECHNIQUES FOR THE IMPERIAL VALLEY 1979 AFTERSHOCKS.

This paper describes some of the features of the latest processing improvements that the U. S. Geological Survey (USGS) is currently applying to strong-motion accelerograms from the national network of permanent stations. At the same time it introduces the application of this processing to the set of Imperial Valley aftershocks recorded following the main shock of October 15, 1979. Earlier processing of the 22 main shock recordings provided corrected accelerations, velocity and displacement, response spectra, and Fourier spectra.

Conference Paper↗
USGS1983

Euler-Lagrangian computation for estuarine hydrodynamics

The transport of conservative and suspended matter in fluid flows is a phenomenon of Lagrangian nature because the process is usually convection dominant. Nearly all numerical investigations of such problems use an Eulerian formulation for the convenience that the computational grids are fixed in space and because the vast majority of field data are collected in an Eulerian reference frame. Several examples are given in this paper to illustrate a modeling approach which combines the advantages of both the Eulerian and Lagrangian computational techniques.

Conference Paper↗
USGS1983

Eastern Devonian shales: Organic geochemical studies, past and present

The Eastern Devonian shales are represented by a sequence of sediments extending from New York state, south to the northern regions of Georgia and Alabama, and west into Ohio and to the Michigan and Ilinois Basins. Correlatives are known in Texas. The shale is regionally known by a number of names: Chattanooga, Dunkirk, Rhinestreet, Huron, Antrim, Ohio, Woodford, etc. These shales, other than those in Texas, have elicited much interest because they have been a source of unassociated natural gas. It is of particular interest, however, that most of these shales have no associated crude oil, in spite of the fact that they have some of the characteristics normally attributed to source beds. This paper addresses some of the organic geochemical aspects of the kerogen in these shales, in relation to their oil generating potential. Past organic geochemical studies on Eastern Devonian shales will be reviewed. Recent solid state 13C NMR studies on the nature of the organic matter in Eastern Devonian shales show that Eastern Devonian shales contain a larger fraction of aromatic carbon in their chemical composition. Thus, despite their high organic matter contents, their potential as a petroleum source rock is low, because the kerogen in these shales is of a "coaly" nature and hence more prone to producing natural gas.

Conference Paper↗
USGS1985

REGIONAL GROUND-WATER-QUALITY NETWORK DESIGN.

This paper describes the approach used in designing a regional network to monitor the complex ground-water-quality conditions in the San Joaquin Valley, California. The actual network approximates the ideal network with the constraint of primarily using wells that are already being monitored by someone for some purpose. Further inventories of monitoring networks and installation of some specialized monitoring wells will be needed. Use of statistical network analysis techniques is also needed to make network improvements. Following these actions, the actual network will more closely approximate the ideal network in providing information on ground-water-quality trends, contaminant sources, prevention of future sources of contamination, monitoring well distributions, sampling frequencies, and constituents to be monitored.

Conference Paper↗
USGS1984

REMOTE SENSING IN NORTHERN ARIZONA: S. P. CINDER CONE AND LAVA FLOW.

The objective of this poster paper is to present a site-specific atlas showing a wide variety of remote sensing data sets collected for the area of S. P. Mountain and lava flow (basaltic-andesite) in north-central Arizona. The data set to be displayed includes a number of radar images, representing three wavelength regions (1-, 3- and 25-cm), multiple incidence angles, look directions, and polarization combinations, in addition to thermal infrared scanner imagery, multispectral scanner imagery, aerial and ground photography, micro- and macro topography, and four-frequency, multipolarization radar scatterometer spectra. The expression of different surface units on the S. P. lava flow are effectively displayed on the ERIM four-channel images by the registration and combination of the four bands. Multi-color imagery of band combinations demonstrate the information content of multi-channel SAR imagery as well as the suitability of extending data manipulation methods developed for Landsat data to SAR data.

Conference Paper↗
USGS1985

STATE WATER RESOURCES RESEARCH INSTITUTE PROGRAM: GROUND WATER RESEARCH.

This paper updates a review of the accomplishments of the State Water Resources Research Program in ground water contamination research. The aim is to assess the progress made towards understanding the mechanisms of ground water contamination and based on this understanding, to suggest procedures for the prevention and control of ground water contamination. The following research areas are covered: (1) mechanisms of organic contaminant transport in the subsurface environment; (2) bacterial and viral contamination of ground water from landfills and septic tank systems; (3) fate and persistence of pesticides in the subsurface; (4) leachability and transport of ground water pollutants from coal production and utilization; and (5) pollution of ground water from mineral mining activities.

Conference Paper↗
USGS1985

EARTHQUAKE PERFORMANCE OF A BRIDGE DECK AND ABUTMENT.

During the 24 April 1984 Morgan Hill Earthquake (M equals 6. 1), 15 channels of acceleration records were obtained at the site of the I-280-680/US 101 interchange 12 km west of the epicenter. These records include free field measurements as well as the acceleration response at one of the supporting column bases, and at three locations in one of the spans of the three-span continuous post-tensioned box-girder deck. The purpose of this paper is to review the performance of this bridge deck and its abutment through the study of these records. The objective in extensively instrumenting a bridge deck or any structure is to obtain relevant response data to study its behaviour during strong motion events and ultimately extrapolate conclusions for improved design.

Conference Paper↗
USGS1985

Application of the 1:2,000,000-scale data base: A National Atlas sectional prototype

A study of the potential to produce a National Atlas sectional prototype from the 1:2,000,000-scale data base was concluded recently by the National Mapping Division, U. S. Geological Survey. This paper discusses the specific digital cartographic production procedures involved in the preparation of the prototype map, as well as the theoretical and practical cartographic framework for the study. Such items as data organization, data classification, digital techniques, data conversions, and modification of traditional design specifications for an automated environment are discussed. The bulk of the cartographic work for the production of the prototype was carried out in raster format on the Scitex Response-250 mapping system.

Conference Paper↗
USGS1985

MODELING HYDRAULIC PROBLEMS USING THE CVBEM AND THE MICROCOMPUTER.

The Complex Variable Boundary Element Method (CVBEM) offers an effective and efficient means for modeling two-dimensional potential and related flow problems. The method has been applied to various hydraulic and hydrodynamic problems - surface water, ground water, and other flows - and has proven its accuracy, reliability and usefulness. The paper describes the CVBEM and its application.

Conference Paper↗
USGS1985

SPECTRAL REFLECTANCE METHOD TO MEASURE ACID DEPOSITION EFFECTS ON BUILDING STONE.

As part of the National Acid Precipitation Assessment Program (NAPAP), the U. S. Geological Survey is cooperating with other agencies to test the effects of acid deposition on building stone. A 10-year test-site study has been organized for the purpose of correlating possible stone deterioration with environmental factors. In Summer 1984, slabs of building stone, 3 by 2 by 2 inches, were exposed to the atmosphere at four test sites where the pH of precipitation and other meteorological variables are continuously monitored. This paper examines the development of one experimental technique used in this study - the application of diffuse spectral reflectance methods for laboratory and in situ measurement of those properties of stone which may be affected by acid deposition.

Conference Paper↗
USGS1985

U. S. G. S. MODULAR GROUND-WATER FLOW MODEL: DESIGNED TO BE UNDERSTOOD AND ADAPTED.

The paper discusses a carefully designed model program and its complementary complete description of all of the physical and mathematical concepts used in the model. The model program consists of a series of independent subroutines called modules. Modules are grouped by hydrologic function into 'packages. ' A report describing the model was written in three levels. At one level the hydrologic concepts on which the model is based are explained. The second level describes how the concepts were incorporated into the program. The third level describes specific modules in sufficient depth to permit modifications to the model.

Conference Paper↗
USGS1984

QUANTIFICATION OF IN-SITU GAS HYDRATES WITH WELL LOGS.

This study evaluates in detail the expected theoretical log responses and the actual log responses within one stratigraphically controlled hydrate horizon in six wells spaced throughout the Kuparuk Oil Field. Detailed examination of the neutron porosity and sonic velocity responses within the horizon is included. In addition, the theoretical effect of the presence of hydrates on the neutron porosity and sonic velocity devices has been examined in order to correct for such an effect on the calculation of formation properties such as porosity and hydrate saturation. Also presented in the paper is a technique which allows the conclusive identification of a potential hydrate occurrence.

Conference Paper↗
USGS1984

DEFINITION FOR TALC.

Talc is a naturally occurring single-phase mineral having the approximate chemical formula Mg//3Si//4O//1//0(OH)//2 and a specific type of crystal structure. Talc commonly forms by hydrothermal alteration of rocks rich in magnesium and iron (ultramafic rocks) and by low-grade thermal metamorphism of siliceous dolomites. The fact that talc often occurs in association with other minerals, or that its crystalline form may be platy, fibrous, acicular, or massive, does not modify its definition. The paper discusses variations in talc chemical composition and its crystal structure and describes its characteristic physical properties.

Conference Paper↗
USGS1985

NUMERICAL MODELING OF FINE SEDIMENT PHYSICAL PROCESSES.

Fine sediment in channels, rivers, estuaries, and coastal waters undergo several physical processes including flocculation, floc disruption, deposition, bed consolidation, and resuspension. This paper presents a conceptual model and reviews mathematical models of these physical processes. Several general fine sediment models that simulate some of these processes are reviewed. These general models do not directly simulate flocculation and floc disruption, but the conceptual model and existing functions are shown to adequately model these two processes for one set of laboratory data.

Conference Paper↗
USGS1985

TRENDS IN BOREHOLE GEOPHYSICS FOR MINERAL EXPLORATION: ASSAYING AND REMOTE DETECTION.

Several borehole geophysical techniques have been developed in recent years. Assaying technique development has been concentrated on nuclear methods, with some progress being made on using electrical and magnetic properties for mineral identification. Adaptation of conventional surface geophysical techniques to the borehole for locating near-misses of mineralized zones has led to the development of borehole resistivity, electromagnetic (EM), gravity and magnetic methods to the borehole environment. This paper discusses some of the applications and pitfalls of these new techniques.

Conference Paper↗
USGS1984

DISCRIMINATION OF GRANITOIDS AND MINERALIZED GRANITOIDS IN THE MIDYAN REGION, NORTHWESTERN ARABIAN SHIELD, SAUDI ARABIA, BY LANDSAT MSS DATA-ANALYSIS.

Landsat multispectral scanner (MSS) band and band-ratio databases of two scenes covering the Midyan region of northwestern Saudi Arabia were examined quantitatively and qualitatively to determine which databases best discriminate the geologic units of this semi-arid and arid region. Unsupervised, linear-discriminant cluster-analysis was performed on these two band-ratio combinations and on the MSS bands for both scenes. The results for granitoid-rock discrimination indicated that the classification images using the MSS bands are superior to the band-ratio classification images for two reasons, discussed in the paper. Yet, the effects of topography and material type (including desert varnish) on the MSS-band data produced ambiguities in the MSS-band classification results. However, these ambiguities were clarified by using a simulated natural-color image in conjunction with the MSS-band classification image.

Conference Paper↗