Mapping hydrothermal alteration with Landsat Thematic Mapper data

Knepper, Daniel H.

doi:10.1029/ft182p0013

Cited by 10 publications

(13 citation statements)

References 11 publications

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“…The long-wavelength edge of this absorption extends into the visible, absorbing blue and some green light and creating the characteristic red, orange, and yellow colors of such minerals. This ratio is similar to the ASTER 2/1 ratio described by Rockwell (2012), and is commonly used to highlight ferric iron minerals (Knepper, 1989(Knepper, , 2010Rockwell, 1989). …”

Section: Ferric Iron 1 "Redness" Indexmentioning

confidence: 69%

“…Only the reflective bands were used for this study, and have a ground instantaneous field of view (GIFOV, or ground pixel size), of 30 meters. Band ratios, which highlight variation in reflectance between wavelength regions measured by the various bands, or channels, of the sensor, have been the simplest and most widely used analysis method applied to TM data (Crippen, 1989;Knepper, 1989Knepper, , 2010Rockwell, 1989).…”

Section: Description Of Automated Analysis Methodologymentioning

confidence: 99%

“…2), and the Landsat 5/7 ratio is used to highlight this broad mineral group (Knepper, 1989(Knepper, , 2010Rockwell, 1989). Carbonate minerals such as calcite and dolomite, Fe-OHbearing minerals such as epidote, and Mg-OHbearing phyllosilicate minerals such as chlorite, talc, and serpentine ("CEC" mineral group) have SWIR absorptions at slightly longer wavelengths that are only partially covered by the bandpass of Landsat band 7 ( fig.…”

Section: Clay-sulfate-mica-marble Indexmentioning

confidence: 99%

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Automated mapping of mineral groups and green vegetation from Landsat Thematic Mapper imagery with an example from the San Juan Mountains, Colorado

Rockwell¹

2013

Scientific Investigations Map

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Section: Ferric Iron 1 "Redness" Indexmentioning

confidence: 69%

Section: Description Of Automated Analysis Methodologymentioning

confidence: 99%

Section: Clay-sulfate-mica-marble Indexmentioning

confidence: 99%

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Automated mapping of mineral groups and green vegetation from Landsat Thematic Mapper imagery with an example from the San Juan Mountains, Colorado

Rockwell¹

2013

Scientific Investigations Map

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“…Band ratio 4/2 is useful for detecting ferric (Fe 3+ ) iron oxides such as hematite and blue spectral regions (Rockwell, 1989;Knepper, 1989;. Thus, band ratio 4/2 commonly enhances the reddish color from ferric iron minerals (Sabins, 1999;Dehnavi et al, 2010;Shalaby et al, 2010;Knepper, 2010) even if they are not present in high concentration.…”

Section: Band Ratioingmentioning

confidence: 99%

Aeromagnetic and spectral expressions of rare earth element deposits in Gallinas Mountains area, Central New Mexico, USA

Zhou

Gammons

et al. 2018

Interpretation

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KeywordNew Mexico, Gallinas Mountains, Aeromagnetic, Landsat, 2D magnetic modeling Interpretation 2 ABSTRACT The Gallinas Mountains located in the conjunction of Lincoln County and Torrance County, New Mexico, USA are a series of alkaline volcanic rocks intruded into Permian sedimentary rocks. The Gallinas Mountains area is known to host fluorite and copper as veins containing bastnasite while hydrothermally altered rocks associated with iron oxides have been found in the area as well. In this study, multispectral band ratio method was used for surface mineral interpretation by processing satellite image, while aeromagnetic inversion method was applied using aeromagnetic data, digital elevation model and physical properties for 2-D subsurface structure modeling. Bastnasite has higher magnetic susceptibility than the host rocks and surrounding sedimentary rock whereas magnetization of iron oxides (magnetite & hematite) is much stronger than bastnasite; both of them can contribute to a positive aeromagnetic anomaly. Results of this study hypothesize the possible presence of mineralogies and lithologies among the Gallinas Mountains area, indicating the presence of a positive magnetic anomaly that is possibly resultant from both bastnasite and iron oxides.

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“…Knepper (1989) 93 proposed specific band ratios for the delineation of hydroxyl-bearing minerals, hydrated sulfates and carbonates, vegetation, and iron-oxides and hydroxides using Landsat TM bands, namely the red-green-blue (R:G:B) composite of ratios 5∕7∶3∕1∶3∕4 (where 5∕7, 3∕1, and 3∕4 are ratios of the TM bands 5 and 7, 3 and 1, and 3 and 4, respectively), used mainly for geological remote sensing mapping. Other ratio RGB combinations, such as Gozzard ratios 5∕7∶4∕7∶4∕2 are known to be prospective for iron, chromium, nickel, and platinum group metal resources.…”

Section: Knepper Ratios and Principal Component Analysismentioning

confidence: 99%

Assessment of remote sensing-based classification methods for change detection of salt-affected areas (Biskra area, Algeria)

Afrasinei

Melis

Buttau

et al. 2017

J. Appl. Remote Sens

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In the Wadi Biskra arid and semiarid areas, sustainable development is restricted by land degradation processes such as secondary salinization of soils. Being an important highquality date production region of Algeria, this area needs continuous monitoring of desertification indicators, hence highly exposed to climate-related risks. Given the limited access to field data, appropriate methods were assessed for the identification and change detection of salt-affected areas, involving image interpretation and automated classifications employing Landsat imagery, ancillary and multisource ground truth data. First, a visual photointerpretation study of the land cover and land use classes was undergone according to acknowledged methodologies. Second, two automated classification approaches were developed: a customized decision tree classification (DTC) and an unsupervised one applied to the principal components of Knepper ratios composite. Five indices were employed in the DTC construction, among which also is a salinity index. The diachronic analysis was undergone for the 1984 to 2015 images (including seasonal approach), being supported by the interpreted land cover/land use map for error estimation. Considering also biophysical and socioeconomic data, comprehensive results are discussed. One of the most important aspects that emerged was that the accelerated expansion of agricultural land in the last three decades has led and continues to contribute to a secondary salinization of soils

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Mapping hydrothermal alteration with Landsat Thematic Mapper data

Cited by 10 publications

References 11 publications

Automated mapping of mineral groups and green vegetation from Landsat Thematic Mapper imagery with an example from the San Juan Mountains, Colorado

Automated mapping of mineral groups and green vegetation from Landsat Thematic Mapper imagery with an example from the San Juan Mountains, Colorado

Aeromagnetic and spectral expressions of rare earth element deposits in Gallinas Mountains area, Central New Mexico, USA

Assessment of remote sensing-based classification methods for change detection of salt-affected areas (Biskra area, Algeria)

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