Generation and interpretation of geophysical images with examples from the Rae Province, northwestern Canada shield

Geophysics ◽  
1990 ◽  
Vol 55 (8) ◽  
pp. 977-997 ◽  
Author(s):  
H. John Broome
Keyword(s):  
Gamma Ray ◽  
Shear Zones ◽  
Gamma Ray Spectrometry ◽  
Data Sets ◽  
Aeromagnetic Data ◽  
Different Types ◽  
Geologic Maps ◽  
Vertical Gravity ◽  
Shaded Relief ◽  
Radiometric Data

Different types of images generated from gravity, magnetic, and gamma ray spectrometry data from the Rae Province of the Canadian shield were compared with each other and geologic maps to evaluate their effectiveness for displaying the geologically relevant content of the data sets. Shading methods were useful for enhancing weak directional anomalies in the aeromagnetic data. Multi‐directional, shaded‐relief images produced by overlaying three colored, shaded‐relief images are useful for analysis of anomalies associated with structure. Vertical gravity derivative images display a continuous gravity feature linking the Wager Bay and Amer Lake shear zones that is obscured on the Bouguer gravity intensity image. Detailed vertical magnetic derivative images of the shear zone clearly displayed anomalies associated with the internal structure. Composite images generated using three different geophysical parameters show correlations between the magnetic, gravity, and radiometric data which can be related to the geology. Subtle variations in uranium, thorium, and potassium concentrations determined by gamma ray spectrometry can be effectively displayed using ternary radioelement images

ASSESSMENT OF NATURAL RADIOACTIVITY LEVELS AND RADIOLOGICAL HAZARDS IN BUILDING MATERIALS

2020 ◽  
Vol 188 (3) ◽  
pp. 316-321
Author(s):  
Fei Tuo ◽  
Xuan Peng ◽  
Qiang Zhou ◽  
Jing Zhang
Keyword(s):  
Building Materials ◽  
Gamma Ray ◽  
Absorbed Dose ◽  
Gamma Ray Spectrometry ◽  
Absorbed Dose Rate ◽  
Radium Equivalent Activity ◽  
Radiological Hazards ◽  
Radium Equivalent ◽  
Different Types ◽  
Radioactivity Levels

Abstract Radioactivity of 226Ra, 232Th, and 40K were measured in a total of 92 samples, including eight commonly used types of building materials that were obtained from local manufacturers and suppliers in Beijing. Concentrations were determined using high-purity germanium gamma-ray spectrometry. The 226Ra, 232Th, and 40K activity concentrations in all samples varied from 10.1 to 661, 3.3 to 555 and 3.2 to 2945 Bq per kg with an average of 127.8, 114.8, and 701.5 Bq per kg, respectively. The potential radiological hazards were estimated by calculating the absorbed dose rate (D), radium equivalent activity (Raeq), external hazard (Hex), and internal hazard (Hin) indices. The investigated building materials were classified into different types according to the radioactivity levels. Results from this research will provide a reference for the acquisition, sales, and use of building materials. Attention should be paid to the use of coal cinder brick, ceramic, and granite in the construction of dwellings.

scholarly journals Magnetic and gamma-ray spectrometric airborne geophysical data for investigating potential mineral resources and generating geoscientific knowledge in Colombia

2021 ◽  
Vol 48 (Spl.1) ◽  
Author(s):  
Ismael Enrique Moyano Nieto ◽  
Renato Cordani ◽  
Marcela Lara ◽  
Óscar Rojas ◽  
Manuel Puentes ◽  
...  
Keyword(s):  
Land Use ◽  
Land Use Planning ◽  
Gamma Ray ◽  
Geophysical Methods ◽  
Mineral Resources ◽  
Gamma Ray Spectrometry ◽  
Data Sets ◽  
Access To Information ◽  
Airborne Geophysical Data ◽  
Geological Research

The Servicio Geológico Colombiano has made available several airborne magnetometry and gamma-ray spectrometry datasets. The information was acquired in 15 blocks that cover approximately 520,000 square  kilometers of Colombian territory, representing more than 850,000 linear kilometers of information. The data  were collected along flight lines separated by 500 meters or 1000 meters, depending on the area, with sampling rates of 10 Hz (8 meters) and 1 Hz (80 meters) for the magnetometry and gamma-ray spectrometry  data, respectively. The information is stored in 30 databases separated for each block and for each of the geophysical methods used. The Servicio Geológico Colombiano has provided a web portal that provides  detailed specifications for each database and allows interested parties to see the terms and conditions to  access the datasets and to check possible restrictions on access to information. To date, there is no  geophysical database in Colombia with the coverage and resolution of these data sets, which will be very  useful for geological research and research on potential mineral resources and to support geohazard monitoring, land-use planning and providing a baseline dataset for environmental monitoring. 

Using radiometric data to identify æolian dust additions to topsoil of the Hillston district, western NSW

Soil Research ◽  
2003 ◽  
Vol 41 (8) ◽  
pp. 1439 ◽  
Author(s):  
S. R. Cattle ◽  
S. N. Meakin ◽  
P. Ruszkowski ◽  
R. G. Cameron
Keyword(s):  
Gamma Ray ◽  
Rapid Assessment ◽  
Clay Content ◽  
Gamma Ray Spectrometry ◽  
Catchment Scale ◽  
Aeolian Dust ◽  
Aeolian Sediments ◽  
Wide Range ◽  
Radiometric Data ◽  
Dust Accumulation

The identification and characterisation of æolian dust additions to Australian soil profiles has been attempted using a wide range of analytical techniques. Such techniques are often reliant on specialised equipment and operator expertise, but do not necessarily yield information on the spatial distribution of deposited dust across the landscape. An airborne geophysical technique which measures naturally occurring gamma-rays may now assist in the rapid assessment of dust accumulation sites at the catchment scale. This technique, known as gamma ray spectrometry or radiometrics, assesses the potassium (K), uranium (U), and thorium (Th) contents of the Earth's surface, and may potentially distinguish æolian sediments from the underlying rock or in situ developed soil profile by their differing K, U, and/or Th-bearing mineral suites. This paper summarises a study of this technique for identifying æolian dust in topsoils of the Hillston district in western New South Wales. Using airborne with follow-up ground-based radiometric data, a variable relationship was established between large K signatures and apparent topsoil dust accumulations, which were identified as containing appreciable feldspar and illite. The previously established correlation between topsoil clay content and eTh (equivalent Th) concentration was also observed in this region, indicating that the technique may allow for rapid identification of landform features with significant clay and silt enrichment, as often occurs with dust accession. Despite the ubiquity of æolian sediments in this region, the radiometric data were moderately effective in discriminating different dune systems and may therefore represent a useful initial technique for discerning likely areas of dust accumulation in this environment. However, in areas influenced by fluvial sediments, the radiometric signatures were not necessarily indicative of the topsoil dust content.

A test of detailed Nd isotope mapping in the Grenville Province: delineating a duplex thrust sheet in the Kipawa–Mattawa region

2006 ◽  
Vol 43 (4) ◽  
pp. 421-432 ◽  
Author(s):  
M K Herrell ◽  
A P Dickin ◽  
W A Morris
Keyword(s):  
Shear Zone ◽  
Shear Zones ◽  
Data Sets ◽  
Aeromagnetic Data ◽  
Thrust Sheet ◽  
Grenville Province ◽  
Nd Isotope ◽  
Tectonic Model ◽  
Thrust Sheets ◽  
Archean Crust

Over sixty new neodymium model ages were determined on orthogneisses from the Kipawa–Mattawa region of the Grenville Province to refine previous Nd isotope mapping work in this area. The combined Nd data sets support a tectonic model involving three major thrust sheets in the Kipawa area, separated by major shear zones. The uppermost sheet is correlated with the Allochthonous Polycyclic Belt, represented in the study area by the Lac Watson nappe, along with two allochthonous klippen. These have Nd model ages < 1.8 Ga, consistent with previous work. Within the underlying Parautochthonous Belt, previous workers identified a second major shear zone, separating rocks with Archean and Proterozoic crystallization ages, respectively. These two thrust sheets also have distinct Nd isotope signatures. The lowermost sheet consists of metamorphosed but otherwise relatively pristine Archean crust with Nd model ages > 2.6 Ga, whereas the overlying sheet consists of magmatically reworked Archean parautochthon with model ages from 1.8–2.6 Ga. A residual magnetic-field map developed from aeromagnetic data was compared with the terrane boundaries determined from isotopic data. The aeromagnetic data accurately reflect the margin of relatively pristine Archean crust in the study area, but this boundary does not correspond to the Allochthon Boundary Thrust. Instead, this boundary resulted from downcutting of the basal shear zone of the allochthon. This caused décollement of the strongly reworked Archean parautochthon to generate a duplex thrust sheet that was transported northwestwards over pristine Archean crust.

Determination of attenuation coefficients of some wood materials based on thickness and chemical composition

2014 ◽  
Vol 92 (9) ◽  
pp. 968-972 ◽  
Author(s):  
B. Saritha ◽  
A.S. Nageswara Rao
Keyword(s):  
Andhra Pradesh ◽  
Gamma Ray ◽  
Mass Attenuation Coefficient ◽  
Gamma Ray Spectrometry ◽  
Attenuation Coefficients ◽  
Different Types ◽  
Mass Attenuation Coefficients ◽  
Experimental Values ◽  
Mass Attenuation

The variation of linear attenuation coefficients with the densities of different samples is investigated in this paper. For this study, different types of soft wood and hard wood samples were collected from the Pakal forest area of the Warangal district, Andhra Pradesh, India. The linear and mass attenuation coefficients of different wood samples are measured using gamma ray spectrometry based on NaI(Tl) scintillation detector at the gamma ray energies of 661.6 and 59.5 keV. The experimental values of mass attenuation coefficient are compared with that of XCOM data based tool. Figures show the variation of mass attenuation coefficients of wood materials against the absorber thickness (number of mean free paths). From the numerical values, it is inferred that the large thickness of the samples reduces the scattered photons reaching the detector by decreasing the scattering angle.

GAMMA‐RAY SPECTROMETRY IN CENTRAL MOROCCO

Geophysics ◽  
1975 ◽  
Vol 40 (2) ◽  
pp. 331-343 ◽  
Author(s):  
A. Demnati ◽  
H. Naudy
Keyword(s):  
Gamma Ray ◽  
Total Count ◽  
Gamma Ray Spectrometry ◽  
Distribution Maps ◽  
Geologic Maps ◽  
Uranium Distribution ◽  
Low Sensitivity

Correlations between radiometric, aeromagnetic, and geologic maps for the central part of Morocco are shown. Some geologic boundaries are closely followed by the total count. The relatively low sensitivity of the system (400 cu in detector, flown at 150 m) is adequate for producing radioactivity and radioelement distribution maps in this area with a high percentage of outcrop. Maps of thorium count, potassium count, and their ratio emphasize various geologic features. Uranium distribution maps are not presented because the area does not contain really characteristic anomalies in this channel.

scholarly journals RECOGNITION OF GOLD MINERALIZATION FAVORABILITY ZONES THROUGH AIRBORNE GAMMA-RAY SPECTROMETRY AND MAGNETOMETRY IN BRUSQUE AND BOTUVERÁ REGION, SOUTHERN BRAZIL

2018 ◽  
Vol 36 (3) ◽  
pp. 1 ◽  
Author(s):  
Bruno Macchioni Pereira ◽  
Francisco Jose Fonseca Ferreira
Keyword(s):  
Hydrothermal Alteration ◽  
Gamma Ray ◽  
Gold Mineralization ◽  
Shear Zones ◽  
Magnetic Data ◽  
Gamma Ray Spectrometry ◽  
Southern Brazil ◽  
Santa Catarina ◽  
Index Overlay ◽  
Primary Gold

ABSTRACT. The northeastern portion of Santa Catarina State, southern Brazil, bears important primary gold mineralization associated with granitic intrusions with potassic and phyllic hydrothermal alteration zones and a phase shear zone reactivation. Airborne radiometric and magnetic data were applied in the study area through the use of gamma-ray spectrometry (Total Count, K, eTh and eU) and suggestive parameters of hydrothermal alteration as Kd, Ud and F, in association with geological units, while magnetometry (RTP, THDR, TDR and Signum Transform) was applied in the definition of the structural framework. Geophysical data was interpreted and integrated to geological information, such as lithologic units, structures, shear zones and gold mineralization, using the knowledge driven and index overlay methods in order to define favorable targets. The geophysical and geological data exhibit good correlation, as seen in the gamma-ray spectrometric domains and magnetic lineaments, and the favorability map shows important target areas for primary gold mineralization. It was possible to observe in the geophysical maps that shear zones and faults have more influence in the occurrences than potassic and phyllic hydrothermal alteration related to granitic intrusions.Keywords: geophysical exploration, knowledge-driven, Dom Feliciano Belt.RESUMO. A porção nordeste do estado de Santa Catarina, sul do Brasil, possui importantes mineralizações auríferas primárias associadas a intrusões graníticas com zonas de alteração hidrotermal potássica e fílica e posterior fase de reativação de zonas de cisalhamento. Dados radiométricos e magnéticos aerogeofísicos foram aplicados na área de estudo através do uso de gamaespectrometria (Contagem Total, K, eTh e eU) e parâmetros sugestivos de alteração hidrotermal como Kd, Ud e Parâmetro F. Em associação com unidades geológicas, enquanto a magnetometria (RTP, GHT, ISA e Signum Transform) foi aplicada na definição do arcabouço estrutural. Os dados geofísicos foram interpretados e integrados às informações geológicas, como unidades litológicas, estruturas, zonas de cisalhamento e mineralizações de ouro, utilizando os métodos knowledge-driven e index overlay para definir alvos favoráveis. Os dados geofísicos e geológicos apresentam boa correlação, como visto nos domínios espectrométricos de raios gama e lineamentos magnéticos, e o mapa de favorabilidade mostra áreas-alvo importantes para a mineralização de ouro primária. Foi possível observar nos mapas geofísicos que as zonas de cisalhamento e as falhas têm mais influência nas ocorrências do que as zonas de alteração hidrotermal potássica e fílica relacionada às intrusões graníticas.Palavras-chave: exploração geofísica, knowledge-driven, Cinturão Dom Feliciano.

The use of airborne gamma‐ray spectrometry—A case study from the Mount Isa inlier, northwest Queensland, Australia

Geophysics ◽  
2000 ◽  
Vol 65 (6) ◽  
pp. 1993-2000 ◽  
Author(s):  
Prasantha Michael Jayawardhana ◽  
S. N. Sheard
Keyword(s):  
Spatial Modeling ◽  
Geographical Information Systems ◽  
Gamma Ray ◽  
Digital Data ◽  
Geographical Information ◽  
Gamma Ray Spectrometry ◽  
Data Sets ◽  
Gis Technology ◽  
Mount Isa ◽  
Airborne Survey

An airborne survey was undertaken on the Mount Isa inlier in 1990–1992. During this survey, both airborne magnetic and gamma‐ray spectrometric data were recorded over 639 170 line-km. Because of perceived value of the radiometric data, stringent calibration procedures, including the creation of a test range, were adopted. In addition to the data from the newly‐flown areas, 76 760 line‐km of existing data were acquired from other companies, and were reprocessed and merged with the Mount Isa survey. The total area covered by the Mount Isa airborne survey was 151 300 km2. Over the last five years, several studies have been undertaken that seek to exploit the Mount Isa region gamma‐ray database and maximise the use of radiometrics for mineral exploration. This paper highlights the results of these studies by focussing on radiometric signatures of major mines in the Mount Isa Inlier, radioelement contour maps, geomagnetic/radiometric interpretation maps, lithological mapping, regolith mapping, geochemical sampling, and spatial modeling using geographical information systems (GIS). Due to the recent introduction of GIS technology and better techniques for handling high quality digital data, there has been a revived interest in making more use of image data sets. The integration of raster and vector data sets for both spectral and spatial modeling has maximized the potential of this approach.

scholarly journals Integration of remote sensing and airborne geophysical data applied to geological mapping: a case study of the Vieirópolis region (Paraíba), Rio Grande do Norte Subprovince, Borborema Province

2018 ◽  
Vol 18 (3) ◽  
pp. 89-103 ◽  
Author(s):  
José Ferreira de Araújo Neto ◽  
Glenda Lira Santos ◽  
Igor Manoel Belo de Albuquerque e Souza ◽  
Sandra De Brito Barreto ◽  
Lauro Cézar Montefalco de Lira Santos ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Shear Zone ◽  
Gamma Ray ◽  
Rio Grande ◽  
Shear Zones ◽  
Geological Mapping ◽  
Gamma Ray Spectrometry ◽  
Borborema Province ◽  
Geological Map

The integration of geological data obtained through fieldwork, remote sensing and airborne geophysics has been shown to be efficient in creation of precise geological maps. The Vieirópolis region, sited in the west of the Rio Grande do Norte Subprovince of the Borborema Province, is characteristically made up of rocks intensely deformed by transcurrent shear zones and late brittle structures which control the mineralization of gemmological and industrial minerals. ASTER GDEM and airborne geophysical images (magnetometry and gamma-ray spectrometry) were used in order to enhance the geological knowledge of this region and to facilitate the identification and delimitation of structures and lithologies mapped during stages of fieldwork. Thus, a geological map on a scale of 1:50,000 was achieved, made up of six main lithological units and three new shear zones (Vieirópolis, Lastro and São Pedro), as well as the NE-SW-trending Portalegre Shear Zone. Within the newly mapped structures, the Vieirópolis Shear Zone stands out due to its expressiveness. Aeromagnetometry data suggest that this zone originated on the edge of the Brejo das Freiras Subbasin, part of the Portalegre Shear Zone System. NW-SE, ESE-WNW and E-W lineaments were correlated to lesser extent brittle structures which sometimes transversely cut the regional foliation, allowing pegmatite fluids to rise. The RGB ternary composition map (K, eTh, eU) also corroborates the presence of these structures, besides helping to determine lithological units. In this case study, the integration of direct and indirect data showed to be essential for the understanding and producing of local geological map.

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