Mapping Hydrothermal Alteration With Landsat Thematic Mapper Data
- Keenan Lee,
- Daniel H. Knepper Jr.,
- Fred A. Kruse,
- Ronald W. Marrs and
- Nancy M. Milton
Published Online: 15 MAR 2013
Copyright 1989 by the American Geophysical Union.
Remote Sensing in Exploration Geology: Golden, Colorado to Washington, D.C., June 30-July 8, 1989
How to Cite
Knepper, D. H. (1989) Mapping Hydrothermal Alteration With Landsat Thematic Mapper Data, in Remote Sensing in Exploration Geology: Golden, Colorado to Washington, D.C., June 30-July 8, 1989 (eds K. Lee, D. H. Knepper, F. A. Kruse, R. W. Marrs and N. M. Milton), American Geophysical Union, Washington, D. C.. doi: 10.1002/9781118669877.ch3
- Published Online: 15 MAR 2013
- Published Print: 1 JAN 1989
Print ISBN: 9780875905648
Online ISBN: 9781118669877
- Alternative alteration mapping images;
- Hydrothermal alteration;
- Hydroxyl-bearing minerals, hydrated sulfates and carbonates;
- Image design;
- Landsat Multispectral Scanner (MSS) data;
- Thematic Mapper (TM) data
The association of hydrothermally altered rocks with mineral deposits has long been recognized and applied as an exploration tool. Landsat Multispectral Scanner (MSS) data provide a means of mapping ferric iron oxides and hydroxides (limonite), some of which may be related to altered rocks. Landsat Thematic Mapper (TM) data duplicate this capability and extend detection and mapping to other common alteration minerals, such the clay minerals, carbonates, and micas. In addition, TM data have nearly three times the spatial resolution of MSS data, so mapping potentially hydrothermally altered rocks can be conducted in greater detail.
The key to successfully applying TM data to mapping altered rocks is the design of images that enhance the spectral contrasts between the alteration minerals and other minerals and materials. Band ratio images are most commonly used to measure broad differences between selected parts of spectral reflectance curves and detect the presence of absorption bands that are characteristic of the alteration minerals. Although the interpretation of these images is not without the danger of misidentifying altered rocks, an experienced geologist can usually detect probable false anomalies and focus attention on those anomalies most likely to be related to hydrothermal alteration.