Mapping variations in weight percent silica measured from multispectral thermal infrared imagery—Examples from the Hiller Mountains, Nevada, USA and Tres Virgenes-La Reforma, Baja California Sur, Mexico

• Published in: Remote sensing of environment Vol. 95; no. 3; pp. 273 - 289
• Main Authors: Hook, Simon J., Dmochowski, Jane E., Howard, Keith A., Rowan, Lawrence C., Karlstrom, Karl E., Stock, Joann M.
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 01-04-2005; Elsevier Science
• Subjects: Applied geophysics; Areal geology. Maps; Crystalline rocks; Earth sciences; Earth, ocean, space; Exact sciences and technology; Geologic maps, cartography; Igneous and metamorphic rocks petrology, volcanic processes, magmas; Infrared imagery; Internal geophysics; MODIS/ASTER Airborne Simulator (MASTER); Silica; Weight percent; Mexico; Baja California Sur Mexico; United States; Nevada; MODIS/ASTER Airborne Simulator (MASTER); Weight percent; Silica; Infrared imagery; quartz monzonite; silica; multispectral remote sensing; regression analysis; accuracy; North America; volcanism; basaltic andesite; granites; basalts; silicate rocks; imagery; silicates; infrared methods; thermal analysis; andesites; maps; volcanic rocks; remote sensing; igneous rocks; cartography; monzonites; airborne methods; plutonic rocks
• ISSN: 0034-4257; 1879-0704
• DOI: 10.1016/j.rse.2004.11.020

Remotely sensed multispectral thermal infrared (8–13 μm) images are increasingly being used to map variations in surface silicate mineralogy. These studies utilize the shift to longer wavelengths in the main spectral feature in minerals in this wavelength region (reststrahlen band) as the mineralogy changes from felsic to mafic. An approach is described for determining the amount of this shift and then using the shift with a reference curve, derived from laboratory data, to remotely determine the weight percent SiO
2 of the surface. The approach has broad applicability to many study areas and can also be fine-tuned to give greater accuracy in a particular study area if field samples are available. The approach was assessed using airborne multispectral thermal infrared images from the Hiller Mountains, Nevada, USA and the Tres Virgenes-La Reforma, Baja California Sur, Mexico. Results indicate the general approach slightly overestimates the weight percent SiO
2 of low silica rocks (e.g. basalt) and underestimates the weight percent SiO
2 of high silica rocks (e.g. granite). Fine tuning the general approach with measurements from field samples provided good results for both areas with errors in the recovered weight percent SiO
2 of a few percent. The map units identified by these techniques and traditional mapping at the Hiller Mountains demonstrate the continuity of the crystalline rocks from the Hiller Mountains southward to the White Hills supporting the idea that these ranges represent an essentially continuous footwall block below a regional detachment. Results from the Baja California data verify the most recent volcanism to be basaltic–andesite.