Application of total-count aeroradiometric maps to the exploration for heavy-mineral deposits in the coastal plain of Virginia, with a section on field-spectrometer-data reduction

Abstract

Total-count contoured aeroradiometric maps for the Coastal Plain of Virginia were used in an effort to locate economic heavy-mineral placer deposits. The principle behind this approach is that heavymineral suites commonly contain radioactive minerals that, if the concentration of heavy minerals is exposed at or within inches of the surface, enable the deposit to be located by use of airborne instruments because of its radiometric contrast with the host sediment. Detailed and regional geologic maps, soil maps, land-use and landcover maps, information on fertilizer use, and ground-spectrometer data were used to study aeroradiometric anomalies for efficient exploration. Aeroradiometric anomalies in the Coastal Plain of Virginia have three general causes. First, the most intense anomalies are associated with cultural features, such as roads made of granitic material. Second, most anomalies of high to intermediate intensity are associated with land used for agricultural purposes and evidently are caused by applications of radioactive fertilizer. Third, anomalies of intermediate to low intensity are associated with heavy-mineral deposits. Results of this study show that aeroradiometric anomalies associated with heavy-mineral accumulations in the Coastal Plain of Virginia have ground radiometric spectra in which thorium is the strongest component and uranium and potassium are lesser components. Heavy-mineral accumulations found in this study by use of the aeroradiometric data are not considered to be of economic importance, mostly because of the low percentage of economic minerals in the heavy-mineral suites and also because of other factors such as the very fine grained nature of the host sediments and competing land use.

NURE geochemical and geophysical surveys: Defining prospective terranes for United States placer exploration

“…:fine-sand facies deposits (Grosz, 1983). Other anomalies in the Lower Cretaceous to Pleistocene sediments in the Coastal Plain of Virginia indicate important areas for exploration.…”

“…Between 1975 and1983, this U.S. Department of Energy program acquired stream sediment geochemistry and airborne spectral gamma-ray radiation data for the conterminous 48 States and Alaska. · The HSSR, one component of the NURE program, entailed collection and analysis of samples of sediment (stream, soil, talus, playa, and others), ground water, surface water, and vegetation to determine concentrations of uranium and other selected elements (Arendt and others, 1980).…”

“…More recently, airborne gamma-ray radiation and highresolution magnetic surveys were shown to be useful in outlining targets for sampling (Robson and Sam path, 1977;Force and others, 1982;Grosz, 1983;Grosz and others, 1989). Induced polarization is another promising technique for onshore and offshore placer exploration (Wynn and others, 1990).…”

Titanium mineral resources in heavy-mineral sands in the Atlantic coastal plain of the southeastern United States

“…4). Grosz (1983) carried out an exploration assessment of the HMS deposits along the coastal plain of Virginia. His study employed total-count aeroradiometric maps followed by field checking of 80 identified anomalies by ground radiometric surveys and sediment samples.…”

“…A study of the HMS deposits of the coastal plain in Virginia by Grosz (1983) applied total-count aeroradiometric maps as a technique to explore for HMS. His study found that when surveyed on the ground, HMS accumulations produce radiometric spectra of intermediate to low intensity with thorium producing the strongest radiation component and with lesser contributions from uranium and potassium.…”