Relative dating of Hawaiian lava flows using multispectral thermal infrared images: A new tool for geologic mapping of young volcanic terranes

Abstract

The weathering of Hawaiian basalts in arid and semiarid environments is accompanied by change in their thermal infrared emittance spectra. The spectral differences can be measured and mapped with multispectral imaging systems. The differences appear to be related to the degree of development, preservation, and alteration of glassy crusts; the oxidation of iron; and the accretion of silica‐rich surface veneers. Because the measurements are quantitative and in image format, they are useful for estimating relative ages in geologic mapping of lava flows. In Hawaii this technique is most diagnostic for distinguishing among sparsely vegetated flows less than 1.5 ka in age.

Mid-Infrared (8.1–12.5 μm) Imaging of Mercury

“…The Thermal Infrared Multispectral Scanner (TIMS) uses six channels corresponding to six wavelength ranges in the mid-infrared (see Table V) for remotely sensing, with airborne imagery, rock and mineral composition on Earth (see Hook et al 1999 and references therein). The TIMS six wavelength locations have been carefully studied and shown to be effective for identifying a wide range of rocks and minerals in airborne imagery and ground observations of the desert southwest (Abbott 1990) and characterizing lava flows (Kahle et al 1988) on Earth. A modified TIMS approach has also been used successfully by Christensen (1998) using four channels to study the IRIS and IRTM spectra from Acidalia Planitia (Mars) to discover that the IRTM 4-pt spectra show similarities with plagioclase feldspar minerals, clays, and pyroxenes with an overall match to feldspar.…”

Impact of Environmental Factors on the Spectral Characteristics of Lava Surfaces: Field Spectrometry of Basaltic Lava Flows on Tenerife, Canary Islands, Spain

“…Roughness controls the lava surface porosity and will therefore influence the type and rate of surface weathering [44,45]. Lava surface roughness has been previously correlated with emission in the thermal infrared range [14] and backscatter of radar signals [8,46]. We here wish to investigate whether lava flow surface roughness also influences the spectral reflectance in the VNIR and SWIR ranges.…”

“…Satellite data acquired in the visible to near infrared, thermal infrared ranges as well as radar signals have been proven useful in mapping lava flows [11][12][13]. Other studies highlighted the possibility to discriminate weathered lavas and even to relatively date them [14][15][16]. All these applications rely on material-specific spectral responses of volcanic surfaces, which may vary both spatially and temporally.…”

“…Improving the understanding of the spectra of lava surfaces has the potential to help to better interpret the spectra of volcanic areas recorded on satellite images and, therefore, to facilitate the realization of our long-term goals, i.e., mapping and dating lava flows. Whereas several studies have investigated the factors controlling the contrasted characteristics of lava in the thermal infrared and radar wavelength ranges [14,[17][18][19], only limited attention has been dedicated to unravelling the factors controlling the large spectral contrasts observed within lava flow fields in the visible to near-infrared range. There is therefore a need to build a spectral library of lava surfaces, to find out how they behave spectrally, to characterize how this spectral behavior varies in space and time and to investigate which flow characteristics or environmental factors influence these variations.…”

“…This is a complex process controlled by multiple factors such as climate, relief, lithology, vegetation cover, lava age as well as the surface roughness resulting from lava flow emplacement dynamics (e.g., [28,30]). Although oxidation has been reported to increase the slope of the reflectance curve in the visible part of the spectrum over time [15], how lava spectra are progressively influenced by other surface characteristics and environmental conditions (e.g., surface roughness [8,14,16]), and to what extent, and how this understanding could contribute in improving automatic mapping and relative dating of lava flow fields are important questions that remain to be investigated.…”