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Gary L. Raines

Publications and source records attributed to Gary L. Raines.

28 records · Page 2Linked to original sources
USGS1984

REMOTE-SENSING MINERAL DISCOVERIES IN THE MOJAVE DESERT OF CALIFORNIA.

As a result of remote sensing studies in the Mojave Desert of California three previously unknown stockwork molybdenum systems have been discovered. It is not known if economic deposits of molybdenum and associated minerals occur in these areas; there is, however, sufficient data to judge that these areas are worthy of further exploration. The purpose of this paper is to present case histories of two of these discoveries. These discoveries have been made from laboratory analyses of Landsat multispectral scanner images to map limonitic materials and from field reconnaissance to determine if the limonite is due to hydrothermal alteration. In those areas that seemed most promising, airborne spectrometer surveys were employed to mapped Al-OH minerals, and audio-magnetotelluric (AMT) and telluric-traversing surveys were performed to obtain information at depth.

Conference Paper↗
USGS1984

TECHNIQUE FOR ENHANCING DIGITAL COLOR IMAGES BY CONTRAST STRETCHING IN MUNSELL COLOR SPACE.

The Munsell color system can be used to further enhance the appearance of high-quality digital color-composite images. A color-balanced 'standard' color-composite image is first produced using any desired contrast stretching algorithm. The stretched digital data are then transformed into the cylindrical Munsell color space. An enhanced version of a color-composite image is produced by stretching the saturation parameter over the full digital range and inverting the modified Munsell coordinates to red-blue-green (tristimulus) data space. The resulting image has greater color-saturation contrast than the original image, without hue change. Contrast stretching in Munsell color space reduces the correlation between individual bands or ratios and is similar to decorrelation processing based on principal-components transforms. However, principal components are based on data variance, with less variance being explained by each higher order component.

Conference Paper↗
USGS1983

Preliminary map of limonitic hydrothermal alteration for portions of the Needles 1° x 2° quadrangle, Arizona and California

Portions of the Needles quadrangle have been designated by the Bureau of Land Management as potential wilderness areas and are being evaluated by a multidisciplinary team to determine the mineral-resource potential. As a part of this study Landsat images are being used to map the generalized distribution of limonitic materials as a guide to hydrothermal alteration which, in turn, acts as a guide to mineralized systems. The term limonite, defined by Blanchard (1968) as a general term for hydrous iron oxides, is here modified to include any material with the unique spectral reflectance properties of the ferric oxide minerals such as hematite and goethite, as defined by Hunt (1980). The map shows areas of limonitic hydrothermal alteration but does not show hydrothermally altered areas lacking limonitic materials. Table 1 lists, for each hydrothermally altered area detected, the type of alteration and the anomalous trace-element geochemical suite found in that area.

Arizona, California↗
USGS1980

Airborne-biogeochemical survey test-case results

Airborne spectroradiometer surveys over several forest-covered sulfide bodies indicate that mineralization has affected the overlying vegetation; anomalous spectral reflectivity properties can be detected in the vegetation using appropriate remote-sensing interments and data-reduction techniques. Mineralization induces subtle changes in the shape of the chlorophyll a and b absorption spectrum between 550 and 750 nm. The observed spectral variations appear specifically to be on the wings of the broad red chlorophyll bars, centered at about 680 nm.

Sixth Annual Pecora Symposium and Exposition↗
USGS1979

Evaluation of a color-coded Landsat 5/6 ratio image for mapping lithologic differences in western South Dakota

From analysis of a color-coded Landsat 5/6 ratio, image, a map of the vegetation density distribution has been produced by Raines of 25,000 sq km of western South Dakota. This 5/6 ratio image is produced digitally calculating the ratios of the bands 5 and 6 of the Landsat data and then color coding these ratios in an image. Bretz and Shurr compared this vegetation density map with published and unpublished data primarily of the U.S. Geological Survey and the South Dakota Geological Survey; good correspondence is seen between this map and existing geologic maps, especially with the soils map. We believe that this Landsat ratio image can be used as a tool to refine existing maps of surficial geology and bedrock, where bedrock is exposed, and to improve mapping accuracy in areas of poor exposure common in South Dakota. In addition, this type of image could be a useful, additional tool in mapping areas that are unmapped.

Open-File Report↗
USGS1978

Porphyry copper exploration model for northern Sonora, Mexico

The regional tectonic pattern of the porphyry copper province of northern Sonora, Mexico, is similar to, but more complex than, the Colorado mineral belt. Four northeast-trending shear zones, spaced at 30- to 50-kilometer intervals from Hermosillo, Mexico, north to Nogales, Mexico, are interpreted from analysis of lineament data from Landsat-1 images. From comparison with other areas, these zones are believed to have Precambrian ancestry. North-northwest-trending lineaments, which commonly occur along range fronts, are interpreted to be the principal basin and range faults. North-south- and west-northwest-trending lineaments are believed to be related to lesser faults and fractures. Areas of hydrothermal alteration have been mapped on a regional scale by use of digital image-processing techniques. These altered areas occur on the flanks of the northeast-trending shear zones, generally near intersections with north-northwest-trending lineaments. This tectonic framework with associated alteration is similar to patterns in the Colorado Plateau, the porphyry copper province of Arizona, and central Mexico and is supported by relationships found in limited local mapping. The pattern of northeast-trending shear zones and north-northwest-trending faults in northern Sonora closely resembles the tectonic framework of the Colorado mineral belt. The younger sedimentary and volcanic cover, however, has not been eroded in Sonora as it has been in the Colorado mineral belt. This comparison with the Colorado mineral belt suggests that mineral deposits are most likely to be found in altered areas where a northeast-trending shear zone is intersected by north-northwest-trending faults. Seven areas with these characteristics have been defined in Sonora and are being evaluated by means of regional geophysical and geochemical data.

Sonora↗