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.

Integrated data analysis for mineral exploration: A case study of clustering satellite imagery, airborne gamma-ray, and regional geochemical data suites

Geophysics ◽  
2012 ◽  
Vol 77 (4) ◽  
pp. B167-B176 ◽  
Author(s):  
Detlef G. Eberle ◽  
Hendrik Paasche
Keyword(s):  
Cluster Analysis ◽  
Gamma Ray ◽  
Mineral Exploration ◽  
Landsat Imagery ◽  
Correlated Data ◽  
Geochemical Data ◽  
Data Sets ◽  
Cluster Algorithms ◽  
Manganese Mineralization ◽  
Northern Cape

Partitioning cluster algorithms have proven to be powerful tools for data-driven integration of large geoscientific databases. We used fuzzy Gustafson-Kessel cluster analysis to integrate Landsat imagery, airborne radiometric, and regional geochemical data to aid in the interpretation of a multimethod database. The survey area extends over [Formula: see text] and is located in the Northern Cape Province, South Africa. We carefully selected five variables for cluster analysis to avoid the clustering results being dominated by spatially high-correlated data sets that were present in our database. Unlike other, more popular cluster algorithms, such as k-means or fuzzy c-means, the Gustafson-Kessel algorithm requires no preclustering data processing, such as scaling or adjustment of histographic data distributions. The outcome of cluster analysis was a classified map that delineates prominent near-to-surface structures. To add value to the classified map, we compared the detected structures to mapped geology and additional geophysical ground-truthing data. We were able to associate the structures detected by cluster analysis to geophysical and geological information thus obtaining a pseudolithology map. The latter outlined an area with increased mineral potential where manganese mineralization, i.e., psilomelane, had been located.

scholarly journals PROSPECTING PHOSPHORITES USING AIRBORNE GEOPHYSICS IN NORTHEASTERN GOIÁS STATE – BRAZIL

2012 ◽  
Vol 30 (4) ◽  
pp. 459 ◽  
Author(s):  
Chris Busnello Fianco ◽  
Roberta Mary Vidotti ◽  
Augusto César Bittencourt Pires ◽  
Adriana Chatack Carmelo
Keyword(s):  
Information Integration ◽  
Gamma Ray ◽  
Wave Length ◽  
Field Work ◽  
Short Wave ◽  
Statistical Correlation ◽  
Geological Mapping ◽  
Geochemical Data ◽  
Gamma Ray Spectrometry ◽  
Airborne Geophysics

A área do projeto está localizada na parte central do Brasil, na região nordeste do Estado de Goiás. As rochas fosfáticas ocorrem no Grupo Bambuí, na parte leste da Faixa de Dobramentos Brasília (FDB), na borda oeste do Cráton do São Francisco. As rochas mineralizadas na área de estudo estão associadas a calcários com apatita. Buscando maior eficiência e rapidez na descoberta de novos alvos prospectivos de rochas sedimentares fosfáticas, foi realizado o processamento dos dados aerogeofísicos juntamente com a correlação estatística dos dados geoquímicos. A integração destes dados proporcionou alvos potenciais que serão investigados com mapeamento geológico e geofísica terrestre (gamaespectrometria) para produzir parâmetros de calibração e comparação com as informações de geofísica aérea. A integração de informações geológicas e mapas de estimativa de eU e P mostraram que rochas ígneas e crostas lateríticas apresentam os teores mais altos de eU e eTh, conforme esperado. Entretando foram identificadas anomalias com pequeno comprimento de onda nos sedimentos das formações Serra de Santa Helena e Sete Lagoasdo Grupo Bambuí, onde são conhecidas ocorrências de corpos fosfáticos na área. O próximo passo deste trabalho será a investigação em campo destas anomalias encontradas, por meio de perfis geológicos e gamaespectrometria terrestre. ABSTRACT. The project area is located in the central part of Brazil, on the northeast region of Goiás State. The phosphatic rocks occur in the Bambuí Group, on the eastern portion of the Faixa de Dobramentos Brasília – Brasília Fold Strip (FDB), on the western border of the São Francisco Craton. In the area under investigation, themineralized rocks are associated with limestone and apatite. In order to discover new prospective targets of phosphatic sedimentary bodies, a faster and more objective airborne geophysics data processing method was carried out together with statistical correlation of geochemical data. The integration of these data identified potential mineralized targets to be checked with geologic mapping and ground geophysics (gamma-ray spectrometry) to produce a parameter of calibration and comparison with the airborne geophysical information. Integration of geologic information and estimate maps of eU and P shows that igneous rocks and lateritic crusts present the high estgrades of uranium and thorium elements, as expected. However, short wave length anomalies were identified in sediments of the Serra de Santa Helena and Sete Lagoas formations (Bambuí Group), where known phosphatic bodies occur in the studied area. The next step of this work will be field work to check these anomalies, with geological mapping and ground gamma-ray profiles.Keywords: applied geophysics, multiple regressions, phosphorites, uranium, Bambuí Group.

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.

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.

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