Remote sensing for porphyry copper deposits in southern Arizona

Abrams, Michael J.; Brown, D.; Lepley, Larry K.; Sadowski, R. M.

doi:10.2113/gsecongeo.78.4.591

Cited by 250 publications

(113 citation statements)

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“…For example, the LS and CA SWIR indices target bands that measure hydroxyl (2.2 µm) and carbonate (2.35 µm) absorption features, respectively. At-sensor radiance band ratios reduce atmospheric and topographic influences, including illumination variability (Abrams et al, 1983;Mather, 1987;Kääb, 2005 …”

Section: Swir Indicesmentioning

confidence: 99%

Geochemical characterization of supraglacial debris via in situ and optical remote sensing methods: a case study in Khumbu Himalaya, Nepal

2012

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Abstract. Surface glacier debris samples and field spectra were collected from the ablation zones of Nepal Himalaya Ngozumpa and Khumbu glaciers in November and December 2009. Geochemical and mineral compositions of supraglacial debris were determined by X-ray diffraction and X-ray fluorescence spectroscopy. This composition data was used as ground truth in evaluating field spectra and satellite supraglacial debris composition and mapping methods. Satellite remote sensing methods for characterizing glacial surface debris include visible to thermal infrared hyper-and multispectral reflectance and emission signature identification, semi-quantitative mineral abundance indicies and spectral image composites. Satellite derived supraglacial debris mineral maps displayed the predominance of layered silicates, hydroxyl-bearing and calcite minerals on Khumbu Himalayan glaciers. Supraglacial mineral maps compared with satellite thermal data revealed correlations between glacier surface composition and glacier surface temperature. Glacier velocity displacement fields and shortwave, thermal infrared false color composites indicated the magnitude of mass flux at glacier confluences. The supraglacial debris mapping methods presented in this study can be used on a broader scale to improve, supplement and potentially reduce errors associated with glacier debris radiative property, composition, areal extent and mass flux quantifications.

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Section: Swir Indicesmentioning

confidence: 99%

Geochemical characterization of supraglacial debris via in situ and optical remote sensing methods: a case study in Khumbu Himalaya, Nepal

2012

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“…열수변질대를 구성하는 열수변질광물들은 가시 근적외선, 단파장적외선, 열적외선 영역의 특정파장대 역에서 특징적인 분광학적 흡수특성을 보인다 (Abrams et al, 1983;Spatz and Wilson, 1995). 진행되고 있다 Rowan et al, 2006;Di Tommaso and Rubinstein, 2007 (Steven and Ratt, 1960;Buchanan, 1981;Stoffregen, 1987;Sillitoe, 1993; (Koh, 1996), 이 중 해남층은 다 시 6개 화산암류와 서로 시기가 다른 3개의 화성복합 체로 세분된다 (Bowden, 2007).…”

Section: 여러 유형의 금속광상 중에서 반암동광상은 열수변unclassified

Identification of Advanced Argillic-altered Rocks of the Haenam Area, Using by ASTER Spectral Analysis

Lee¹,

Kim²,

Moon³

2011

Economic and Environmental Geology

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The Haenam epithermal mineralized zone is located in the southwestern part of South Korea, and hosts low sulfidation epithermal Au-Ag deposit (Eunsan-Moisan) and clay quarries (Okmaesan, Seongsan, and Chunsan). Epithermal deposits and accompanying hydrothermal alteration related to Cretaceous volcanism caused large zoned assemblages of hydrothermal alteration minerals. Advanced argillic-altered rocks with mineral assemblages of alunite-quartz, alunite-dickite-quartz, and dickite-kaolinite-quartz exposed on the Okmaesan, Seongsan, and Chunsan area. Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), with three visible and near infrared bands, six shortwave infrared bands, and five thermal infrared bands, was used to identify advanced argillic-altered rocks within the Haenam epithermal mineralized zone. The distinct spectral features of hydrothermal minerals allow discrimination of advanced argillic-altered rocks from non-altered rocks within the study area. Because alunite, dickite, and kaolinite, consisting of advanced argillic-altered rocks within the study area are characterized by Al-O-H-bearing minerals, these acid hydrothermal minerals have a strong absorption feature at 2.20 µm. The band combination and band ratio transformation cause increasing differences of DN values between advanced argillic-altered rock and non-altered rock. The alunite and dickite-kaolinite of advanced argillic-altered rocks from the Okmaesan, Seongsan, and Chunsan have average DN values of 1.523 and 1.737, respectively. These values are much higher than those (1.211 and 1.308, respectively) of non-altered area. ASTER images can remotely provide the distribution of hydrothermal minerals on the surface. In this way good relation between ASTER spectra analysis and field data suggests that ASTER spectral analysis can be useful tool in the initial steps of mineral exploration.

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“…Pionecr work by a nwnbcr of authors, including Abrams et al (1977Abrams et al ( , 1983, Rowan & Kahle (1982) and Podwysocki et al (1983), demonstrated the potential of the 2.2 )lm region of the electromagnetic spectrum for detecting hydroxyl-bearing minerals and carbonates usually associated with hydrothermal alteration processes. This was added to previous work demonstrating the usefulness of the visible/near infrared region of thc spectrum for mapping Fe3~_bearing minerals (Rowan el al., 1974(Rowan el al., , 1977Goetz et aI., 1975;Goetz & Rowan, 1981).…”

Section: Txtroductionmentioning

confidence: 99%

Evaluating geoscan AMSS MK-II for gold exploration in the Fazenda Maria Preta District, Rio Itapicuru greenstone belt, Bahia State, Brazil

Prado

Crósta

1997

Bol. IG-USP, Sér. cient.

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The Rio ltapicuru Greenstone Belt (RI GB), located in north-eaSlem Brazil, is an importanl gold producing region. II hosts two important mining districts, the Faunda Brasileiro and the Fazenda Maria Prela, owned by Companhia Vale do Rio Once (CVRO), plus a number of gold OCCll!Tenccs. all associated with hydrothermal alteralion along shear zones. In 1992, Geoscan multispectral scanner data were acquired for mineral exploration purposes over more than 7,500 km' in this greenstone helt. Geoscan AMSS is a 24-band airborne scanner, with 5 meter spatial resolution Standard image processing (e.;hniques, applied immediately after data acquisition, defmed some spectral anomalies, particularly due to silicification and oxidation, which could be due either to hydrothermal alteration or to weathering processes. We have reprocessed the Geoscan data over a portion of the RIGB in order to define possible anomalies due to hydrothermal alteration minerals, using the feature-oriented principal component selection (FPCS) technique, modified for use with Geos.can data. Laboratory reflectance spectra of residual soils were acquired to establish superficial expression of hydroth ennal minera ls that OCCur in ~ub-surfac e and to guide image processing and interpretation. This Jed 10 the production of "mineral component" images, in which the spalial distribution of some minerals are shown. Results of the spectral analysis of soil samples showed that goethite may be used as a surface indicator of hydrothennal alteration and that it is not possible to differentiate the alteration zones from surrounding rocks based on the hydroxyl or carbonate spectral features RESUMO o Greenstone Belt do Rio Jtapicuru (RIGB). localizado no nordeste do Brasil, e uma importante regiilo produtora de ouro no pais. Ele comern dois importantes distritos mineiros, 0 da Fazenda Brasileiro e Fazenda Maria Prela, pertenccntes a Companhia Vale do Rio Doce (CVRD), alem de diversas outras ocorrencias auriferas. todas elas associadas a processo de a1tera~~o hidrotermal ao longo de zonas de cisalhamento. Em 1992. imagens do sensor multiespectral Geoscan foram obtidas ern mais de 7.500 kml do greenstone. 0 Geos.call AMSS Mk-Il t urn sensor aeroportado que cobre 24 banda~ espectrais, com S metros de resolu~a.o espaciaJ no caso deste levantamemo. Tecn icas padrao de proccssamento de imagens, aplicadas imediatamente ap6s 0 levantamento. definiram uma serie de anomalias cspcctrais, re lacionadas a processos de si1icifica~ilo e oxidao;.1o. que podem tanto ser devidos a processes de altera~a.o 'Companhia de RecUT"" Minerais (CPRM) -Servi~o Geologico do Brasil. Manaus. AM. Brasil. llrtstituto de Oeocienei"siUNTCAMP. Campinas. SP_ Brasil

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Remote sensing for porphyry copper deposits in southern Arizona

Cited by 250 publications

References 0 publications

Geochemical characterization of supraglacial debris via in situ and optical remote sensing methods: a case study in Khumbu Himalaya, Nepal

Geochemical characterization of supraglacial debris via in situ and optical remote sensing methods: a case study in Khumbu Himalaya, Nepal

Identification of Advanced Argillic-altered Rocks of the Haenam Area, Using by ASTER Spectral Analysis

Evaluating geoscan AMSS MK-II for gold exploration in the Fazenda Maria Preta District, Rio Itapicuru greenstone belt, Bahia State, Brazil

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