Interpreting aerial gamma-ray surveys utilising geomorphological and weathering models

Dickson, B.L.; Fraser, Stephen; Kinsey-Henderson, Anne

doi:10.1016/s0375-6742(96)00017-9

Cited by 48 publications

(44 citation statements)

References 8 publications

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“…The altered areas in the image are verified, using the available geophysical data . The previous studies have shown that the elevated potassium in the phyllic zone is often observed around the mineralization areas and also acid sulfate conditions resulting from weathering of near surface sulfides can result in Th mobilization from host rocks and can precipitate with iron in gossan 29 .The porphyry copper deposits in the Kerman region are associated with a distinct magnetic low, relative to the host rocks, a potassium high and resistivity low. 30 have developed a model called porphyry picker based on analysis of geophysical data.…”

Section: -Discussionmentioning

confidence: 96%

<title>Digital image processing for lithological and alteration mapping using SPOT multispectral data: a case study of Pariz area, Kerman Province, Iran</title>

Ranjbar

Roonwal

2002

Remote Sensing for Environmental Monitoring, GIS Applications, and Geology

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Tertiary porphyry deposits in Iran are an important source of Cu, Mo and locally Au. Most of the known porphyry Cu deposits are located in the Central Iranian Volcanic Belt(CIVB). Pariz area is located within this belt and is chosen as a test area to evaluate remote sensing data at one such area, and use of these data in exploration of the other parts of CIVB. Eight known mineralization sites were chosen in the area, which are mainly porphyry type. SPOT images in XS mode are used to study geology as well as hydrothermal alteration in the Pariz area, where soil and vegetation cover is substantially poor. Different approaches such as band ratioing, principal component analysis, I-S-H decorrelation processing, digital filtering and hybrid composite were used to enhance the diagnostic features associated with the lithologies as well as the hydrothermal alteration. Color combinations of the principal components, I-S-H transformation and 2/1 ratio have proved to be the best image enhancement techniques for geological studies in such areas. Lineament analysis has shown that the areas with known ore occurrence and the hydrothermally altered areas are closely associated with the higher photolineament factor values. Comparison of geophysical and remote sensing data has shown that there is a good correlation between the airborne geophysical and remote sensing data in the area.

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Section: -Discussionmentioning

confidence: 96%

<title>Digital image processing for lithological and alteration mapping using SPOT multispectral data: a case study of Pariz area, Kerman Province, Iran</title>

Ranjbar

Roonwal

2002

Remote Sensing for Environmental Monitoring, GIS Applications, and Geology

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“…Desse processo resultam padrões de distribuição dos radionuclídeos, e radioanomalias, muito diferentes daqueles da rocha original (ADAMS; RICHARDSON, 1960;SAMAMA, 1971;GRANIER, 1973;LANGMUIR, 1978;ROSE et al, 1979;FORTESCUE, 1980;TIEH et al, 1980;GUTHRIE;KLEEMAN, 1986;CARVALHO, 1995;VIERS et al, 1997, entre outros). As mencionadas coberturas são as verdadeiras fontes das emissões gama, como demonstram com muita propriedade Silva (1994), Dickson et al (1996), Dickson e Scott (1997), Wilford et al (1997) e Souza (1998). Estabelecer uma relação direta entre a concentração de Ra, obtida conforme mencionado, e possíveis fluxos de Rn no solo, pode levar a imprecisões consideráveis nas paisagens elementares.…”

Section: Discussionunclassified

Modelos De Exalação De Radônio Em Paisagens Tropicais Úmidas Sobre Granito

Rebelo¹,

Bittencourt²,

Mantovani³

2003

GEO

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RESUMOForam estabelecidas e analisadas as principais relações entre intensidades de exalação de radônio ( 222 Rn e 220 Rn) e os elementos morfológicos e dinâmicos de paisagens tropicais úmidas, com o objetivo de elaborar modelos de exalação de Rn adaptados a este tipo de paisagens, e aplicáveis na escala de pequenos núcleos habitacionais. Em uma vertente sobre rocha granítica com teores normais em U e Th, e caracterizada pela associação Latossolo-Solo Podzólico, os produtos de atuação dos processos supergênicos, com destaque para a transição de latolização em podzolização, e o atual regime hídrico do aqüífero freático, foram relacionados aos processos radioativos de geração, emanação e migração de Rn, verificando-se como tais inter-relações afetam a sua exalação nas paisagens. Tal abordagem foi fundamentada nos conceitos de sistema pedológico de transformação e de geoquímica de paisagens, além de conceitos da física e geologia nucleares e elementos climatológicos e hidrogeológicos do macroambiente, num enfoque interdisciplinar, tridimensional e sistêmico. Às vertentes configuradas em paisagens elementares; eluvial, transeluvial e supraqual associam-se diferentes geoformas, tipos e espessuras de solos residuais e radioanomalias com diferentes intensidades e formas de hospedagem de U e de Th. Com base em tais elementos, suas relações espaciais com o sistema freático, e considerando a umidade dos solos na capacidade de campo, as possibilidades de maiores taxas de exalação de Rn, sobretudo 222 Rn, são nas paisagens supraqual e transeluvial. Na paisagem eluvial, a despeito da existência de intensas anomalias gama, devido principalmente ao acúmulo de minerais resistatos com U e Th e compostos de Th, os fluxos de Rn são menos significativos. Assim, no contexto enfocado, os produtos da alteração supergênica, organizados num sistema vertente, são materiais em que as taxas de exalação de radônio são mais elevadas do que as medidas na rocha inalterada subjacente. O entendimento do comportamento do U, Th, Ra e Rn no ambiente superficial tornou possível estabelecer modelos previsionais de exalação de Rn adaptados às paisagens elementares, em escalas compatíveis com pequenos núcleos habitacionais ou em unidades residenciais.Palavras-chave: modelos de exalação de radônio, paisagens tropicais úmidas, processos suergênicos, processos radiotivos, sistema pedológico de transformação.

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“…Therefore, hydrothermal alteration minerals (sericite, biotite, K-feldspars and many K-bearing clay minerals) can be detected and mapped by using radiometric data [10]- [12]. Elevated potassium in the sericite zone is often observed around the mineralization areas and also acid sulfate conditions resulting from weathering of near surface sulfides can result in eTh mobilization from host rocks and can precipitate with iron in gossan [13]. Several workers have reported a decrease in magnetization and changes in 40 K and the 40 K/eTh ratio associated with hydrothermally altered zones [12], [14].…”

Section: Introductionmentioning

confidence: 99%

Application of Airborne Geophysical and ASTER Data for Hydrothermal Alteration Mapping in the Sar-Kuh Porphyry Copper Area, Kerman Province, Iran

Honarmand¹

2016

OJG

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Known deposits are appropriate sites for investigating significant exploratory keys that could be helpful in mineral exploration in corresponding regions or similar areas. This study was performed to delineate hydrothermal alteration model and some geophysical characteristics of the SarKuh porphyry copper deposit located within the southern part of the central Iranian Cenozoic magmatic belt (CICMB). Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) images have been used to produce hydrothermal alteration map using a fractal-aided spectral angle mapper (SAM) method. Airborne data were used to study magnetic-radiometric properties of the deposit. Image processing of ASTER images and laboratory studies proved the presence of two types of phyllic ale ration called intense and weak phyllic based on abundance of sericite mineral. It realized that radiometric anomalies of 40 K, eTh and eU are limited to boundary of phyllic zone. Radiometric ratios e.g. eTh/ 40 K were good enough to enhance phyllic zone.

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Interpreting aerial gamma-ray surveys utilising geomorphological and weathering models

Cited by 48 publications

References 8 publications

<title>Digital image processing for lithological and alteration mapping using SPOT multispectral data: a case study of Pariz area, Kerman Province, Iran</title>

<title>Digital image processing for lithological and alteration mapping using SPOT multispectral data: a case study of Pariz area, Kerman Province, Iran</title>

Modelos De Exalação De Radônio Em Paisagens Tropicais Úmidas Sobre Granito

Application of Airborne Geophysical and ASTER Data for Hydrothermal Alteration Mapping in the Sar-Kuh Porphyry Copper Area, Kerman Province, Iran

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