Crustal Imaging and Characterization Team
Task Contact: Trude King
To date, there has been limited research to establish the reliability of using ASTER TIR (Thermal Infrared) data to map unaltered volcanic rocks. Therefore, the initial part of this study will focus on laboratory studies to establish the spectral characteristics of unaltered volcanic rocks as a function of both composition, primarily SiO content, and grain size frequency distribution in the TIR wavelength region of the electromagnetic spectrum. Because the chemical and mineralogical composition and the grain size distribution of the volcanic rocks will have major effects on the TIR spectra, it will be necessary to establish and document how each of these variables affect the reflectance spectra. If the laboratory investigation shows it is possible to differentiate between the various extrusive igneous rocks, additional testing using remotely sensed ASTER data (in an area with supporting AVIRIS data) will be conducted.
The island of Hawaii has been shown to be an excellent natural laboratory in which to evaluate the spectral effects of climate, biota, and topography on the weathering of rocks of relatively uniform basaltic composition and several ages. Within a relatively small area, there are a wide variety of microclimates acting on these rocks. Soils developed on the basalts have already been characterized by other workers (primarily colleagues from University of California, Santa Barbara) using field observations and laboratory techniques including isotopic and XRD analyses. The Kohala region of the island of Hawaii provides both a chronosequence and a climosequence of soils that are ideal for determining mineralogical differences as a function of depth (profile) and surficial expression (lateral). The existing chemical and mineralogical data will provide a means of testing the results of spectroscopic analysis.
To begin to link the reseach objectives, we propose to develop mineral maps for the Kohala region and Molokai using both Landsat 7 ETM+ multispectral data and existing AVIRIS (2001) data available from JPL.
During fiscal year 2007 we will continue our examination of the spectroscopic charateristics of soils. We will acquire field data for selected climosequences and chronosequences of soils to determine mineralogic composition based on spectral characteristics. These works will support our previous work in Hawaii. The results of the spectroscopic investigations will be compared with XRD data to help determine the accuracy of the specroscopic measurements.
We will also continue to expand the analysis of ASTER data to support the expanding California soil geochemistry studies. These works will be used to provide a base map of selected portions of the California study area. Results from the ASTER mapping will be compared with previous results of AVIRIS mapping in the Sulphur Bank Area. The ASTER data will provide a spectroscopic study linking source and deposition areas along Cache Creek to the Sacremento Valley. These works will support on-going studies in Task 3 " Developing new methods of vegetation characterizationusing remote sensing for investigating the role of geologic processes and soil mineral composition on landscaperesponse to disturbances".
Volcanic rocks (rhyolite, andesites, and basalts) were collected, chemically characterized, and spectroscopically measured. Initial measurements using the Nicolet 760 spectrometer were made on USGS standards (powders) and materials (solids and sieved and grain size sorted powders) from the USGS Hunt and Salisbury collection. Spectroscopic analyze show differences between the spectra of the samples at the resolution of the Nicolet instrument. Preliminary data for the sizesorted samples indicate that the primary difference between the spectra of the various size intervals is the level of reflection.
An invited presentation was given at the Soil Geochemistry Workshop in March as part of the Project interaction with the Geochemical Landscapes Project. The presentation provided an overview of the variety of remote sensing techniques, highlighted their strengths and weaknesses, and provided recommendations regarding potential integrated studies using remotely sensed data.
In fiscal year 2004, samples representing a soil climosequence were collected from the Kohala Coast of Hawaii in April. The work was completed with cooperation from NRCS (Mike Holman) and Lopaka Lee (Geochemical Landscapes Project). The sample locations and sampling protocols followed those previously described by Oliver Chadwick. More than 35 samples were collected from 6 sites.
Soil samples from Bangladesh were also spectrally characterized in co-operation with George Breitt in fiscal year 2004. The spectroscopic analysis showed: Unambiguous differentiation between Fe- and Mn-bearing samples; Samples containing hematite and goethite as well as mixtures of the two can readily be identified; Samples from Dupai are very similar and differ from the remaining samples in the they contain no epidote; Samples with As contents greater than 530 occur in goethite-rich soils.
 |
|
|
Mineral Resources |
Eastern / Central / Western / Alaska / Minerals Information |
| Crustal Imaging & Characterization / Spatial Data |
U.S. Department of the Interior |
U.S. Geological Survey
URL: http://crustal.usgs.gov
Page Contact Information: CICT Webmaster
Page Last Modified:
