Remote sensing for resources development and environmental management: Remote sensing for resources development and environmental management

damen, m. c. j.

Bibliographic data

Multivolume work

Persistent identifier:: 856342815

Title:: Remote sensing for resources development and environmental management

Sub title:: proceedings of the 7th international Symposium, Enschede, 25 - 29 August 1986

Year of publication:: 1986

Place of publication:: Rotterdam; Boston

Publisher of the original:: A. A. Balkema

Identifier (digital):: 856342815

Language:: English

Additional Notes:: Volume 1-3 erschienen von 1986-1988

Editor:: Damen, M. C. J.

Document type:: Multivolume work

Volume

Persistent identifier:: 856662364

Title:: Remote sensing for resources development and environmental management

Sub title:: proceedings of the 7th international Symposium, Enschede, 25 - 29 August 1986

Scope:: VI, Seiten 959-1074

Year of publication:: 2016

Place of publication:: Rotterdam; Boston

Publisher of the original:: A. A. Balkema

Identifier (digital):: 856662364

Signature of the source:: ZS 312(26,7,3)

Language:: English

Usage licence:: Attribution 4.0 International (CC BY 4.0)

Editor:: Damen, M. C. J.

Publisher of the digital copy:: Technische Informationsbibliothek Hannover

Place of publication of the digital copy:: Hannover

Year of publication of the original:: 2016

Document type:: Volume

Collection:: Earth sciences

Chapter

Title:: Invited papers

Document type:: Multivolume work

Structure type:: Chapter

Chapter

Title:: Remote sensing for non-renewable resources: Satellite and airborne multiband scanners for mineral exploration. Alexander F. H. Goetz

Document type:: Multivolume work

Structure type:: Chapter

Symposium on Remote Sensing for Resources Development and Environmental Management/Enschede/August 1986 © 1987Balkema, Rotterdam. ISBN 90 6191 674 7 1009 Remote sensing for non-renewable resources: Satellite and airborne multiband scanners for mineral exploration Alexander F.H. Goetz University of Colorado, Boulder, and Jet Propulsion Laboratory, Pasadena, Calif, USA ABSTRACT: The application of remote sensing techniques to mineral exploration involves the use of both spatial (morphological) as well as spectral information. This paper is directed toward a discussion of the uses of spectral image information and emphasizes the newest airborne and spaceborne sensor developments involving imaging spectrometers. 1 INTRODUCTION Remote sensing has been applied to mineral exploration problems since the first aerial photographs became available. The advent of space imaging systems, beginning with Landsat-1 in 1972, provided a whole new perspective afforded by the synoptic view from orbit. In the early days of Landsat, image data were interpreted directly for spatial information much as had been done with aerial photographs. Mineral exploration relies heavily on structural interpretation (Gold 1980). For the interpretation of structural and geomorphological features, high spatial resolution as well as stereo coverage is desired. The most widely available data at higher spatial resolutions come from the Landsat-4 and -5 Thematic Mapper (Slater 1980) and SPOT which provides stereo coverage (Chevrel et al. 1981). With the application of computer image enhancement techniques, multispectral data could be used to map spectrally different units and, in particular, iron oxide anomalies. During the mid-1970s, it was recognized that broader spectral coverage and higher spectral resolution was necessary to derive meaningful mineralogical information. This realization brought about the development of high spectral resolution systems, both profilers and imagers, to derive surface compositional information with direct application to mineral exploration. 2 BASIS FOR SPECTRAL MEASUREMENTS Incoming solar radiation is either scattered from the Earth's surface or absorbed and re-emitted in the thermal portion of the spectrum. The process of scattering and absorption takes place in the uppermost layers of the surface, in fact, in the upper millimeters. Thus, scattering is a function of the geometric properties of the surface, including particle size and aspect, and the absorption coefficient. The absorption coefficients are a function of wavelength and are brought about by various physical phenomena such as intermolecular vibrations and electronic transitions in atoms bound in the crystal lattices. Re-emission of energy as a function of wavelength is dependent upon the temperature of the surface material and again its physical properties such as particle size and composition. Therefore, by spectral remote sensing it is possible to derive information about the physical properties and composition of the surface cover. The spectral reflectance of minerals in the visible and solar reflected infrared is the result of five different phenomena as shown in Figure 1. The three most important processes contributing to the spectral reflectance of common materials are the electronic processes of charge transfer and crystal feld effects, and the vibrational processes (Hunt 1977) . The Fe-0 charge transfer takes place in the blue and ultraviolet portion of the spectrum and, since iron is ubiquitous, practically all minerals and soils have rising reflectances toward longer wavelength in the visible portion of the spectrum. Electronic transitions in the d-shell electron of the transition elements embedded in the crystal field create absorption features in the visible and near infrared. Again, the most commonly occurring features are related to iron in both the Fe^ + and Fe^ + state. Vibrational processes yield the greatest number of sharp and unique spectral absorption features, mainly in the region 2-2.5 Jim. Overtone bending/stretching vibrations for H2O, OH, AlOH, MgOH, and CO3 produce unique features for identification of the most common surface materials and weathering products. Figure 2 shows representative spectra of common minerals in the 2-2.5 Jim region. Some common rock forming minerals such as quartz ana feldspar do not have diagnostic absorption features in the solar reflected infrared. For silicates the fundamental Si-0 stretching vibrations occur near 9 Jim (Hunt and Salisbury 1974) . The region around the fundamental vibration creates a metallic-like reflectance or reststrahlen band, and, therefore, an emittance minimum, the position of which is diagnostic for the silicate mineral. Figure 3 shows a compilation of emittance spectra ranging from acidic high-quartz rock such as granites to quartz-free, olivine-bearing rocks such as dunite (Lyon 1965). The fundamental stretching vibration frequency depends on the degree of interlocking or oxygen-sharing among the SiC>4 tetrahedra in the crystal lattice. The greater the degree of interlocking, the shorter the wavelength of the reststrahlen band. Recently, a multispectral scanner for the 8-12 Jim region has been constructed to allow spectral imaging in this wavelength region (Kahle and Goetz 1983) . The variation in spectral reflectance among different types of vegetation short of 2.5 Jim is much less pronounced than for minerals. The leaf reflectance is controlled in the visible to 0.7 Jim by the pigments in the leaves, in particular, chlorophyll which has strong absorptions in the blue and far red portion of the visible spectrum. These absorptions involve electronic transitions in the chlorophyll molecules centered around the magnesium component of the photoactive site. The blue absorption is also the result of electronic

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