Combined use of visible, reflected infrared, and thermal infrared images for mapping Hawaiian lava flows

Abrams, M.; Abbott, Elsa A.; Kahle, Anne B.

doi:10.1016/0148-9062(91)91357-w

Cited by 7 publications

(6 citation statements)

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“…We used an Analeet 6200 spectrometer to measure the biconical reflectance of basalt samples, relative to a diffuse gold standard, differences between samples (Figure 1) indicate that AVIRIS (Airborne Visible/Infrared Imaging Spectrometer) and other visible/near-IR instruments with sufficient signal/noise and spectral resolution might be helpful in mapping these younger Hawaiian basalts. The usefulness of visible/near-IR for distinguishing and mapping older basalts has been demonstrated [Abrams et al, 1990], although the iron oxidation and hydroxyl spectral features are much more pronounced than in the younger basalts of this study. Compared to the visible/near-infrared spectra, the thermal infrared reflectance spectra of the younger basalts show more prominent spectral differences related to Si-O bonding, facilitating the distinction of different lava flows.…”

Section: Introductionmentioning

confidence: 60%

Thermal infrared spectral character of Hawaiian basaltic glasses

Crisp¹,

Kahle²,

Abbott³

1990

J. Geophys. Res.

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Multispectral thermal infrared remote sensing of Hawaiian basalts younger than a few hundred years old can be used to discriminate basalt lava flows that are difficult to map with visible and near‐infrared images. Laboratory thermal infrared reflectance spectra of the exposed surfaces of Mauna Loa and Kilauea basalts show systematic changes with age. Fresh glass collected from active lava flows shows a broad reflectance feature between 8 and 12 μm, indicative of a strong degree of disorder. After a few weeks of exposure to the environment the spectra of the top surfaces of samples begin to exhibit spectral features suggestive of ordering into silicate chainlike and sheetlike units. With progressive aging, features of apparent sheetlike structures become the preferred mode. As soon as 3 years after emplacement, a silica‐rich coating can begin to develop on the surfaces, adding another spectral feature to the laboratory reflectance measurements. The Thermal Infrared Multispectral Scanner (TIMS) with six channels between 8 and 12 μm has been used to take advantage of these spectral differences in basalts to map flows in Hawaii. Remote sensing instruments with increased spectral resolution in the thermal infrared would aid in further discrimination of basalts with more subtle differences in age, quenching, and weathering histories.

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Section: Introductionmentioning

confidence: 60%

Thermal infrared spectral character of Hawaiian basaltic glasses

Crisp¹,

Kahle²,

Abbott³

1990

J. Geophys. Res.

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“…[60] However, terrestrial airborne and satellite thermal infrared studies have focused on instruments that differ fundamentally from TES. Multichannel radiometer (''multispectral'') data sets have been used, typically that measure with four to ten bands [e.g., Kahle and Rowan, 1980;Kahle and Goetz, 1983;Gillespie et al, 1984;Abrams et al, 1991;Fujisada and Ono, 1991;King et al, 1996;Barnes et al, 1998;Hook et al, 1999]. Multichannel radiometers can discriminate between certain spectral types, making them productive mapping tools when combined with a field study or other information.…”

Section: Field Studies Neededmentioning

confidence: 99%

Infrared stealthy surfaces: Why TES and THEMIS may miss some substantial mineral deposits on Mars and implications for remote sensing of planetary surfaces

2003

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[1] Infrared spectral observations have yielded many important insights into the nature of Mars. However, spectral effects tied to surface roughness and particle size can make mineral deposits substantially more difficult to detect and identify than is generally known, including for current investigations. The effects hold for Mars and other planets, but here we focus on the impact on the exploration of Mars. Laboratory spectra of pure, smooth-surfaced minerals have previously been used to conclude that the 1996 Global Surveyor Thermal Emission Spectrometer (TES) and the 2001 Mars Odyssey Thermal Emission Imaging System (THEMIS) will detect a mineral deposit that covers $10% of a pixel. Those laboratory spectra have formed the foundation for modeling and interpretations of TES/THEMIS data and for development of the 2003 Mars rover MiniTES. Here, for the first time, we compare TES/THEMIS foundation data to laboratory, field, and unique airborne spectra of rough surfaces. We demonstrate that substantial, well-crystalline, regional mineral deposits, including rock outcrops, can be 100% exposed and remain undetected at the sensitivity of TES/THEMIS. We then detail the physics, which apply to all geologic materials. Previous studies have demonstrated the complicating physical effects for solids versus particulates for a range of minerals, including oxides, sulfates, carbonates, and each of the seven silicate classes. We identify three cases of spectral behavior that can impact interpretations: In Case 1, physical effects cause a target to be undetectable by a given infrared instrument (''infrared stealthy''). In Case 2, variations in spectral contrast mimic abundance variations, which confounds abundance mapping. In Case 3, alteration of the spectral band shape impacts compositional interpretations. Optically smooth materials will be well represented in TES/THEMIS/MiniTES identifications. Conversely, if a material forms an optically rough surface or sufficiently small particles on Mars, then it will be comparatively underrepresented or missed. Surface roughness occurs on three broad scales, and roughness at the grain scale can be a primary variable in whether a mineral is detectable. Nondetection of certain key minerals (e.g., carbonates) can significantly impact geologic and climatic interpretations and landing site selection. The TES/ THEMIS detection threshold may be 10% coverage on the basis of specific laboratory samples, but for field measurements, that prediction represents an idealized lower bound. Interpretations built on nondetection should be revisited after defining the uncertainties in detection capabilities for specific instruments as applied to expected mineral surface textures on Mars, including at the grain scale. The impact on future measurement strategies (including MiniTES) should also be assessed.

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“…[5] Silica rock coatings have a strong effect on TIR spectra. They have been used to distinguish relatively young Hawaiian lava flows in multispectral TIR imaging data [Kahle et al, 1988;Abrams et al, 1991]. Silica coatings on glassy basaltic rocks produce recognizable features in hyperspectral thermal reflectance data, and it is estimated that silica coatings $10 mm thick would essentially mask the substrate in TIR spectra [Crisp et al, 1990].…”

Section: Introductionmentioning

confidence: 99%

Effects of pure silica coatings on thermal emission spectra of basaltic rocks: Considerations for Martian surface mineralogy

Kraft

Michalski

Sharp

2003

Geophysical Research Letters

105

113

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[1] On Mars, silica derived from chemical weathering could precipitate to coat rocks and particles. We suggest that rock coatings of secondary amorphous silica may account for a widespread Martian surface spectral unit previously modeled as andesite or weathered basalt. In a laboratory study, we investigated the effects of synthetic silica coatings on thermal infrared (TIR) spectroscopic measurements. Secondary amorphous silica is spectrally similar to silicate glass and clay spectra used in previous spectroscopic models. Silica coating and substrate spectra combine nonlinearly to produce a composite spectrum of a coated rock. Silica coatings <10 mm thick effectively mask the spectral contribution of a silicate substrate. Therefore, the capability of volumetrically small amounts of silica present as thin coatings on rocks should be considered when seeking explanations for spectral variability of Martian surface materials.

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Combined use of visible, reflected infrared, and thermal infrared images for mapping Hawaiian lava flows

Cited by 7 publications

References 0 publications

Thermal infrared spectral character of Hawaiian basaltic glasses

Thermal infrared spectral character of Hawaiian basaltic glasses

Infrared stealthy surfaces: Why TES and THEMIS may miss some substantial mineral deposits on Mars and implications for remote sensing of planetary surfaces

Effects of pure silica coatings on thermal emission spectra of basaltic rocks: Considerations for Martian surface mineralogy

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