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Mapping the distribution of vesicular textures on silicic lavas using the Thermal Infrared Multispectral ScannerTo investigate the effect of vesicularity on TIMS (Thermal Infrared Multispectral Scanner) imagery independent of chemical variations, we studied a large rhyolitic flow of uniform composition but textural heterogeneity. The imagery was recalibrated so that the digital number values for a lake in the scene matched a calculated ideal spectrum for water. TIMS spectra for the lava show useful differences in coarsely and finely vesicular pumice data, particularly in TIMS bands 3 and 4. Images generated by ratioing these bands accurately map out those areas known from field studies to be coarsely vesicular pumice. These texture-related emissivity variations are probably due to the larger vesicles being relatively deeper and separated by smaller septa leaving less smooth glass available to give the characteristic emission of the lava. In studies of inaccessible lava flows (as on Mars) areas of coarsely vesicular pumice must be identified and avoided before chemical variations can be interpreted. Remotely determined distributions of vesicular and glassy textures can also be related to the volatile contents and potential hazards associated with the emplacement of silicic lava flows on Earth.
Document ID
19940033381
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Ondrusek, Jaime
(NASA Headquarters Washington, DC United States)
Christensen, Philip R.
(NASA Headquarters Washington, DC United States)
Fink, Jonathan H.
(Arizona State Univ. Tempe, United States)
Date Acquired
August 16, 2013
Publication Date
September 10, 1993
Publication Information
Publication: Journal of Geophysical Research
Volume: 98
Issue: B9
ISSN: 0148-0227
Subject Category
Geophysics
Accession Number
94A10036
Funding Number(s)
CONTRACT_GRANT: NSF EAR-90-18216
CONTRACT_GRANT: NAGW-529
Distribution Limits
Public
Copyright
Other

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