HIGH SENSITIVITY GAMMA‐RAY SPECTROMETRY—STATE OF THE ART AND TRIAL APPLICATION OF FACTOR ANALYSIS

Geophysics ◽  
1977 ◽  
Vol 42 (3) ◽  
pp. 549-559 ◽  
Author(s):  
Joseph S. Duval
Keyword(s):  
Factor Analysis ◽  
Gamma Ray ◽  
State Of The Art ◽  
Mineral Exploration ◽  
High Sensitivity ◽  
Original Data ◽  
Gamma Ray Spectrometry ◽  
Similar Data ◽  
Spectrometric Data ◽  
Other Information

The remote sensing of terrestrial gamma rays has application in geologic mapping, mineral exploration, reactor site monitoring, location of lost radioactive sources, measurement of the water equivalence of snow, and soil mapping. Although the state of the art is quite good, there is a need to reexamine the use of detectors other than thallium activated sodium iodide detectors (e.g., plastic scintillators) to improve the corrections used for altitude variations and to present the data as apparent concentrations of potassium, uranium, and thorium rather than as counts per unit of time. In an attempt to improve data analysis, the technique known as factor analysis has been applied to airborne gamma‐ray spectrometric data from a survey in South Texas. This analysis technique allows the geologist/geophysicist to perform a coordinate transformation from the four count rates [potassium (K), equivalent uranium (eU), equivalent thorium (eTh), and total count] and the three ratios, (eU/K, eU/eTh, eTh/K) to a system of three independent coordinates. These three coordinates are constrained to reproduce the total variance of the original data, and the data can be separated into groups using the criterion that similar data points have similar coordinates. The distribution of the separated groups can be mapped for comparison with other information such as the mapped geology. This map of the groups represents a synthesis of all of the radiometric data.

Utilization of airborne gamma ray spectrometric data for geological mapping and radioactive mineral exploration of Gabel Umm Tineidba area, south eastern desert, Egypt

2015 ◽  
Vol 12 (2) ◽  
pp. 149-160 ◽  
Author(s):  
Tharwat H. Abdel Hafeez ◽  
Mohamed A. S. Youssef ◽  
Waheed H. Mohamed
Keyword(s):  
Gamma Ray ◽  
Mineral Exploration ◽  
Eastern Desert ◽  
Geological Mapping ◽  
Gamma Ray Spectrometry ◽  
Spectrometric Data ◽  
South Eastern ◽  
Uranium Exploration ◽  
Geological Information ◽  
Surface Geology

The present work utilizes airborne gamma ray spectrometric data in a trial to refine surface geology of igneous, metamorphic and sedimentary rocks, detect any radioactive mineralization at Gabel Umm Tineidba area South Eastern Desert, Egypt. The study area is covered by rock exposures ranging in age from the Precambrian to Quaternary. Airborne gamma ray spectrometry can be very helpful in mapping surface geology. This provides estimates of the apparent surface concentrations of the most common naturally occurring radioactive elements, such as potassium (K), equivalent uranium (eU) and equivalent thorium (eTh). This is based on the assumption that, the absolute and relative concentrations of these radioelements vary measurably and significantly with lithology. The composite image technique is used to display simultaneously three parameters of the three radioelement concentrations and their three binary ratios on one image. The technique offers much in terms of lithological discrimination, based on color differences and showed efficiency in defining areas, where different lithofacies occur within areas mapped as one continuous lithology. The integration between surface geological information and geophysical data led to detailing the surface geology and the contacts between different rock units. Significant locations or favourable areas for uranium exploration are defined, where the measurements exceed (X+2S), taking X as the arithmetic mean of eU, eU/eTh and eU/K measurements and S as the standard deviation corresponding to each variables. The study area shows the presence of fifteen relatively high uraniferous zone. In addition, the trend analysis based on the total count map and the published geological map shows that, most of the well-developed structural lineaments have NS, ENE, NNE and NNW trends.

scholarly journals Gamma-ray Spectrometry in Geothermal Exploration: State of the Art Techniques

Energies ◽  
2014 ◽  
Vol 7 (8) ◽  
pp. 4757-4780 ◽  
Author(s):  
Alistair McCay ◽  
Thomas Harley ◽  
Paul Younger ◽  
David Sanderson ◽  
Alan Cresswell
Keyword(s):  
Gamma Ray ◽  
State Of The Art ◽  
Gamma Ray Spectrometry ◽  
Geothermal Exploration ◽  
Art Techniques

Composite color images of aerial gamma‐ray spectrometric data

Geophysics ◽  
1983 ◽  
Vol 48 (6) ◽  
pp. 722-735 ◽  
Author(s):  
Joseph S. Duval
Keyword(s):  
Gamma Ray ◽  
Color Image ◽  
Mineral Exploration ◽  
Color Images ◽  
South Texas ◽  
Geologic Mapping ◽  
Partial Synthesis ◽  
Data Set ◽  
Spectrometric Data ◽  
Sample Data

Aerial gamma‐ray data provide estimates of the apparent surface concentrations of potassium (K), equivalent uranium (eU), and equivalent thorium (eTh). These data can be expressed as nine radiometric parameters: K, eU, eTh, eU/eTh, eU/K, eTh/K, eTh/eU, K/eU, and K/eTh. The U.S. Geological Survey (USGS) has developed a technique which combines any three of these parameters to form a composite color image. The color image provides a partial synthesis of the radiometric data that can be used to aid geologic mapping and mineral exploration. The sample data set, from the Freer area in south Texas, illustrates the use of the color images.

The detection of potassic alteration by gamma‐ray spectrometry—Recognition of alteration related to mineralization

Geophysics ◽  
2000 ◽  
Vol 65 (6) ◽  
pp. 2001-2011 ◽  
Author(s):  
Robert B. K. Shives ◽  
B. W. Charbonneau ◽  
K. L. Ford
Keyword(s):  
British Columbia ◽  
Case History ◽  
Gamma Ray ◽  
Mineral Exploration ◽  
Yukon Territory ◽  
Geochemical Data ◽  
Gamma Ray Spectrometry ◽  
Case Histories ◽  
Massive Sulfides ◽  
Porphyry Cu

Canadian case histories document the use of airborne and ground gamma‐ray spectrometry to detect and map potassium alteration associated with different styles of mineralization. These include: volcanic‐hosted massive sulfides (Cu‐Pb‐Zn), Pilley’s Island, Newfoundland; polymetallic, magmatic‐hydrothermal deposits (Au‐Co‐Cu‐Bi‐W‐As), Lou Lake, Northwest Territories; and porphyry Cu‐Au‐(Mo) deposits at Mt. Milligan, British Columbia and Casino, Yukon Territory. Mineralization in two of these areas was discovered using airborne gamma‐ray spectrometry. In each case history, alteration produces potassium anomalies that can be distinguished from normal lithologic potassium variations by characteristic lows in eTh/K ratios. Interpretations incorporating airborne and ground spectrometry, surficial and bedrock geochemistry and petrology show that gamma‐ray spectrometric patterns provide powerful guides to mineralization. This information complements magnetic, electromagnetic, geological, and conventional geochemical data commonly gathered during mineral exploration programs.

scholarly journals Supervised Neural Network Targeting and Classification Analysis of Airborne EM, Magnetic and Gamma-ray Spectrometry Data for Mineral Exploration

2015 ◽  
Vol 2015 (1) ◽  
pp. 1-5
Author(s):  
Karl Kwan ◽  
Stephen Reford ◽  
Djiba Maïga Abdoul-Wahab ◽  
Douglas H. Pitcher ◽  
Nasreddine Bournas ◽  
...  
Keyword(s):  
Neural Network ◽  
Gamma Ray ◽  
Mineral Exploration ◽  
Gamma Ray Spectrometry ◽  
Classification Analysis ◽  
Airborne Em

Introduction to the Special Issue on remote sensing

Geophysics ◽  
1987 ◽  
Vol 52 (7) ◽  
pp. 839-840
Author(s):  
Kenneth Watson
Keyword(s):  
Remote Sensing ◽  
Image Processing ◽  
Near Infrared ◽  
Gamma Ray ◽  
Mineral Exploration ◽  
Remote Sensing Data ◽  
Gamma Ray Spectrometry ◽  
Special Issue ◽  
Spectral Signatures ◽  
Uranium Exploration

In 1977, the first Special Issue on remote sensing published by Geophysics contained papers selected from two special sessions at the 45th Annual International SEG Meeting, October 12–16, 1975, in Denver, Colorado. That first Special Issue consisted of eight papers: four are primarily tutorial (image processing, spectral signatures in the visible and near infrared, microwave spectra of layered media, and factor analysis of gamma‐ray spectrometry), two involve structural interpretations with implications for mineral exploration and seismicity, and two examine multispectral reflectance data for detecting hydrothermal alteration and for uranium exploration. Although these papers indicate the importance of physical properties and models in the interpretation of remote sensing data, the studies were constrained by the instruments that collected the data and by the availability of image‐processing software. Circumstances have changed significantly in the intervening decade, as illustrated in recent review papers (Watson, 1985; Goetz et al., 1983) and demonstrated by the papers in this Special Issue.

Multichannel models for the estimation of radon background in airborne gamma‐ray spectrometry

Geophysics ◽  
1998 ◽  
Vol 63 (6) ◽  
pp. 1986-1996 ◽  
Author(s):  
Brian R. S. Minty
Keyword(s):  
Gamma Ray ◽  
Weighted Least Squares ◽  
Spectral Ratio ◽  
Ratio Method ◽  
Gamma Ray Spectrometry ◽  
Minimization Method ◽  
Full Spectrum ◽  
Spectrometric Data ◽  
Spectral Ratio Method ◽  
Atmospheric Radon

Adequate background correction is a crucial step in processing airborne gamma‐ray spectrometric data because any errors are amplified during subsequent processing procedures. Two multichannel models for the estimation of atmospheric radon background are proposed. The spectral‐ratio method uses the relative heights of uranium (U) series photopeaks to estimate the contribution of atmospheric radon to observed spectra. The full‐spectrum method estimates the atmospheric radon contribution through the weighted least‐squares fitting of potassium (K), U, thorium (Th), and radon component spectra to the observed spectra. Both the spectral‐ratio and full‐spectrum methods are adequately calibrated through the estimation of component spectra from calibration experiments on the ground using radioactive calibration sources and wood to simulate the attenuation of gamma rays by air. The simulated heights used in these calibrations must be mapped onto real heights through calibration flights over an airborne calibration range. The spectral‐ratio method is also adequately calibrated using a heuristic calibration procedure. An iterative minimization method is used to find the optimum values of the calibration constants such that the radon background over suitable calibration lines is best removed.

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