scholarly journals Application of airborne radiometric method in geologic mapping of Malufashi area and Environs, Northwestern Nigeria

2020 ◽  
Vol 8 (2) ◽  
pp. 179
Author(s):  
Ibe Stephen Onyejiuwaka ◽  
Nwokeabia Charity Nkiru
Keyword(s):  
Gold Mineralization ◽  
Value Added ◽  
Geologic Mapping ◽  
Radioactive Elements ◽  
Rock Types ◽  
Reconnaissance Survey ◽  
Airborne Geophysics ◽  
Geologic Map ◽  
Hydrothermal Alteration Zones ◽  
Radiometric Data

In this study, the airborne radiometric data over Masufashi Area of Katsina State and Environs, Northwestern Nigeria were acquired, processed and gridded to generate the concentration maps of percentage Potassium, equivalent Thorium and equivalent Uranium in order to carry out the geologic mapping of the area. Additionally, the abundance ratios, U/Th, U/K and Th/K and the ternary images of the three radioactive elements were produced. The images obtained from the radiometric data showed that the study area comprises five major rock types, based on their variation in the concentration of the three radioactive elements. The actual extent, boundary and distribution of the rock units within the study area were defined; hydrothermal alteration zones were mapped. The altered zones were noted to be associated with mineralization in the quartzite rich schist formation. The interpretation also proved valuable in demarcating some rock types with different properties. The delineated geology and hydrothermally altered zones led to the identification of nine zones with the potentials of gold mineralization. The delineated structures aided the design of the geologic map of the study area. This research showed the value added by airborne geophysics in geologic mapping and recommends the analysis of airborne data as a major phase during reconnaissance survey, prior to geologic mapping.  

Geologic Map of the Park Reservoir Quadrangle, Sheridan County, Wyoming

2020 ◽  
Vol 57 (4) ◽  
pp. 375-388
Author(s):  
Ryan Bessen ◽  
Jennifer Gifford ◽  
Zack Ledbetter ◽  
Sean McGuire ◽  
Kyle True ◽  
...  
Keyword(s):  
Structural Features ◽  
Geologic Mapping ◽  
Rock Types ◽  
Basement Rocks ◽  
Geologic Maps ◽  
Geologic Map ◽  
Tear Fault ◽  
Mapping Techniques ◽  
Wyoming Province ◽  
Bighorn Mountains

This project involved the construction of a detailed geologic map of the Park Reservoir, Wyoming 7.5-Minute Quadrangle (Scale 1:24,000). The Quadrangle occurs entirely in the Bighorn National Forest, which is a popular recreation site for thousands of people each year. This research advances the scientific understanding of the geology of the Bighorn Mountains and the Archean geology of the Wyoming Province. Traditional geologic mapping techniques were used in concert with isotopic age determinations. Our goal was to further subdivide the various phases of the 2.8–3.0 Ga Archean rocks based on their rock types, age, and structural features. This research supports the broader efforts of the Wyoming State Geological Survey to complete 1:24,000 scale geologic maps of the state. The northern part of the Bighorn Mountains is composed of the Bighorn batholith, a composite complex of intrusive bodies that were emplaced between 2.96–2.87 Ga. Our mapping of the Park Reservoir Quadrangle has revealed the presence of five different Archean quartzofeldspathic units, two sets of amphibolite and diabase dikes, a small occurrence of the Cambrian Flathead Sandstone, two Quaternary tills, and Quaternary alluvium. The Archean rock units range in age from ca. 2.96–2.75 Ga, the oldest of which are the most ancient rocks yet reported in the Bighorn batholith. All the Archean rocks have subtle but apparent planar fabric elements, which are variable in orientation and are interpreted to represent magmatic flow during emplacement. The Granite Ridge tear fault, which is the northern boundary of the Piney Creek thrust block, is mapped into the Archean core as a mylonite zone. This relationship indicates that the bounding faults of the Piney Creek thrust block were controlled by weak zones within the Precambrian basement rocks.

Semiautomated geologic mapping using self-organizing maps and airborne geophysics in the Brazilian Amazon

Geophysics ◽  
2012 ◽  
Vol 77 (4) ◽  
pp. K17-K24 ◽  
Author(s):  
Cleyton de Carvalho Carneiro ◽  
Stephen James Fraser ◽  
Alvaro Penteado Crósta ◽  
Adalene Moreira Silva ◽  
Carlos Eduardo de Mesquita Barros
Keyword(s):  
Gamma Ray ◽  
Gold Mineralization ◽  
Brazilian Amazon ◽  
Geophysical Data ◽  
Self Organizing Map ◽  
Self Organizing Maps ◽  
Spectrometric Data ◽  
Rock Types ◽  
Geologic Map ◽  
Self Organizing

A self-organizing map (SOM) approach has been used to provide an integrated spatial analysis and classification of airborne geophysical data collected over the Brazilian Amazon. Magnetic and gamma ray spectrometric data were used to extract geophysical signatures related to the spatial distribution of rock types and to produce a geologic map over the prospective Anapu-Tuerê region. Particular emphasis was given to discriminating and identifying rock types, and the processes related to gold mineralization, which are known to occur in the Anapu-Tuerê region. SOM was able to identify and map distinctive geophysical signatures related to the various geologic units identified on the published geologic map. Furthermore, SOM was able to identify and enhance very subtle signatures derived jointly from the magnetic and gamma ray spectrometric data that could be related to geologic processes present in the area. These results demonstrate the effectiveness of using SOM as a tool for geophysical data analysis and for semiautomated mapping in regions such as the Amazon.

THE NATIONAL GEOLOGIC MAP DATABASE -- A RESOURCE FOR GEOLOGIC MAPPING

2016 ◽  
Author(s):  
David R. Soller ◽  
◽  
Nancy R. Stamm ◽  
Robert C. Wardwell ◽  
Christopher P. Garrity
Keyword(s):  
Geologic Mapping ◽  
Geologic Map

scholarly journals A Remote Sensing-Based Application of Bayesian Networks for Epithermal Gold Potential Mapping in Ahar-Arasbaran Area, NW Iran

2019 ◽  
Vol 12 (1) ◽  
pp. 105 ◽  
Author(s):  
Seyed Mohammad Bolouki ◽  
Hamid Reza Ramazi ◽  
Abbas Maghsoudi ◽  
Amin Beiranvand Pour ◽  
Ghahraman Sohrabi
Keyword(s):  
Remote Sensing ◽  
Bayesian Network ◽  
Hydrothermal Alteration ◽  
Gold Mineralization ◽  
Epithermal Gold ◽  
Alteration Zones ◽  
Mineral Potential ◽  
Potential Map ◽  
Bayesian Network Classifier ◽  
Hydrothermal Alteration Zones

Mapping hydrothermal alteration minerals using multispectral remote sensing satellite imagery provides vital information for the exploration of porphyry and epithermal ore mineralizations. The Ahar-Arasbaran region, NW Iran, contains a variety of porphyry, skarn and epithermal ore deposits. Gold mineralization occurs in the form of epithermal veins and veinlets, which is associated with hydrothermal alteration zones. Thus, the identification of hydrothermal alteration zones is one of the key indicators for targeting new prospective zones of epithermal gold mineralization in the Ahar-Arasbaran region. In this study, Landsat Enhanced Thematic Mapper+ (Landsat-7 ETM+), Landsat-8 and Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) multispectral remote sensing datasets were processed to detect hydrothermal alteration zones associated with epithermal gold mineralization in the Ahar-Arasbaran region. Band ratio techniques and principal component analysis (PCA) were applied on Landsat-7 ETM+ and Landsat-8 data to map hydrothermal alteration zones. Advanced argillic, argillic-phyllic, propylitic and hydrous silica alteration zones were detected and discriminated by implementing band ratio, relative absorption band depth (RBD) and selective PCA to ASTER data. Subsequently, the Bayesian network classifier was used to synthesize the thematic layers of hydrothermal alteration zones. A mineral potential map was generated by the Bayesian network classifier, which shows several new prospective zones of epithermal gold mineralization in the Ahar-Arasbaran region. Besides, comprehensive field surveying and laboratory analysis were conducted to verify the remote sensing results and mineral potential map produced by the Bayesian network classifier. A good rate of agreement with field and laboratory data is achieved for remote sensing results and consequential mineral potential map. It is recommended that the Bayesian network classifier can be broadly used as a valuable model for fusing multi-sensor remote sensing results to generate mineral potential map for reconnaissance stages of epithermal gold exploration in the Ahar-Arasbaran region and other analogous metallogenic provinces around the world.

INVERSION OF AIRBORNE RADIOMETRIC DATA

Geophysics ◽  
1978 ◽  
Vol 43 (1) ◽  
pp. 133-143 ◽  
Author(s):  
P. J. Gunn
Keyword(s):  
Least Squares ◽  
Gamma Rays ◽  
Gamma Ray ◽  
Spectral Representation ◽  
Radioactive Elements ◽  
Intensity Field ◽  
Radiometric Data

The spectral representation describing the gamma ray intensity due to radioactive prismatic sources such as approximate areal distributions of outcropping rocks shows that such intensity fields result from the convolution of factors depending upon the height of the plane of observation, the geometry of the causative bodies, instrumental constants, and the concentrations of radioelements emitting gamma rays. Inverse filters, designed according to the Wiener least‐squares criteria, can deconvolve factors from the observed intensity field to provide direct mappings of the concentrations of radioactive elements.

On the history of the first Russian geological map

2015 ◽  
Vol 34 (2) ◽  
pp. 333-347
Author(s):  
Leonid R. Kolbantsev
Keyword(s):  
Mineral Resources ◽  
Russian Government ◽  
Central State ◽  
Rock Types ◽  
Historical Archive ◽  
History Of ◽  
Geologic Map ◽  
Geological Map ◽  
Academy Of Sciences ◽  
Mining Districts

The earliest Russian geologic map, the “Map of the Environs of the Nerchinsk Mining Establishment (1789–1794)”, was found in the Central State Historical Archive, Leningrad in 1925. At that time it was described by Presnyakov (1927). Shortly after that, the map was lost from view and was not available for study until recently. This paper investigates the provenance and history of the manuscript map in six sheets. It is likely that the Russian government commissioned the map in order to assess the mineral resources of the Nerchinsk district. The map was the result of six summer field seasons where the six base maps showing stream networks and topography were assembled using compasses and tapes. The rock types were superimposed on the base maps and depicted using different colors. The mapping effort was overseen by Egor Barboth de Marny, the director of the Nerchinsk mining establishment, and the fieldwork was undertaken by Dorofey Lebedev, Mikhail Ivanov and Alexey Cheredov. The innovative use of color may have been inspired by earlier maps of mining districts in Germany and suggested by Benedict Franz Johann Hermann, a member of the St. Petersburg Academy of Sciences.

scholarly journals Reconnaissance geochemical and geophysical exploration for gold at Iri gold field, north central Nigeria

2020 ◽  
Vol 18 (2) ◽  
pp. 19-31
Author(s):  
Ahmed Sidi Aliyu ◽  
Nuhu Musa Waziri ◽  
Hadiza Liman Mohammad ◽  
Mohammed Abubakar Mohammed ◽  
Apeh Aromeh Gideon
Keyword(s):  
Gold Mineralization ◽  
Structural Features ◽  
Parent Material ◽  
Geological Mapping ◽  
Magnetic Data ◽  
Geochemical Data ◽  
Aeromagnetic Data ◽  
Geophysical Exploration ◽  
Rock Types ◽  
Soils And Sediments

Reconnaissance geochemical and geophysical exploration for gold was carried out at IRI Gold field. Geological mapping was conducted and rocks, soils and sediments samples were collected. The outcome revealed rocks of the basement complex of Nigeria made up of mainly, Migmatite Gneiss, Older Granite and the Schist. The major lithology in the area is silicified sheared rocks and large quartz vein. Isolated occurrence of undifferentiated schist was found as parent material on which quartzite intruded possibly during a major geological activity. Shattering of the rocks left boulders and rubbles of quartzite all around two major ridges within the study area. The rocks have shown weak geochemical anomaly except in two locations were positive anomalies were observed and identified as target for further exploration. Gold veins are prominent in the area suggesting potential gold mineralization. Interpretation of the aeromagnetic data give the orientations of the structural features, the major structural trend in the area is NE-SW. The lineaments extracted from the magnetic data range in length from 46.43m to about 1251.66m. Most of the lineaments extracted from the area are subsurface within the quartz-mica and migmatites while some of them have surface expressions even though not clearly defined. These magnetic lineaments could be the contacts between two rock types of contrasting magnetic   susceptibility   or   edges   of   structures   that   could   be faults or intrusive bodies. Interpreted satellite data show several subsurface structures which could be hosts to gold mineralization in the area. Results of the geochemical analysis of rocks, soils and sediments were super imposed on the interpreted aeromagnetic data and similar geochemical and geophysical signatures were established.   Index Terms: Gold mineralization, aeromagnetic data, geochemical data, schist belt, Nigeria

scholarly journals GAMMA-RAY SPECTROMETRY FOR DISTINGUISHING ACID AND BASIC ROCKS OF THE SERRA GERAL FORMATION, IN THE SERRA GAÚCHA WINE REGION, BRAZIL

2016 ◽  
Vol 34 (4) ◽  
Author(s):  
Rudi Cesar Comiotto Modena ◽  
Rosemary Hoff ◽  
André Rodrigo Farias ◽  
Jorge Antônio Viel ◽  
Osmar Gustavo Wohl Coelho
Keyword(s):  
Volcanic Rock ◽  
Gamma Ray ◽  
Rio Grande ◽  
Gamma Ray Spectrometry ◽  
Rio Grande Do Sul ◽  
Geophysical Method ◽  
Radioactive Elements ◽  
Rock Types ◽  
Wine Region ◽  
Basic Rocks

ABSTRACT. The gamma-ray spectrometric research has allowed for observation of the distribution of radioactive elements such as K, U and Th for recognizing the radioactive signatures of different rock types. The objective of this study was to evaluate the possibility to distinguish between acid and basic rocks of the Serra Geral Formation, in the Serra Gaúcha wine region in the state of Rio Grande do Sul (Brazil) through gamma-ray spectrometry techniques. This study contributed to geologically...Keywords: geophysical method, wine terroir, volcanic rock. RESUMO. A pesquisa por gamaespectrometria tem permitido observar a distribuição de elementos radioativos, tais como K, U e Th reconhecendo as assinaturas radioativas de diferentes tipos de rocha. O objetivo deste estudo foi avaliar a possibilidade de distinguir entre as rochas ácidas e básicas da Formação Serra Geral, na região vitivinícola Serra Gaúcha, no estado do Rio Grande do Sul (Brasil) por meio de técnicas de gamaespectrometriaPalavras-chave: m´étodos geofísicos, terroir vitivinícola, rocha vulcânica.

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