Long-Wave Infrared

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Exploration Technique: Long-Wave Infrared

Exploration Technique Information
Exploration Group: Remote Sensing Techniques
Exploration Sub Group: Passive Sensors
Parent Exploration Technique: Passive Sensors
Information Provided by Technique
Lithology: Map characteristic minerals associated with hot springs/mineral deposits
Thermal: Map surface temperatures
Long-Wave Infrared:
Long Wave Infrared (LWIR) refers to multi- and hyperspectral data collected in the 8 to 15 µm wavelength range. LWIR surveys are sometimes referred to as "thermal imaging" and can be used to identify relatively warm features such as hot springs, fumaroles, and snow melt. LWIR can also be used to map the distribution of certain minerals related to hydrothermal alterations.
Other definitions:Wikipedia Reegle

Long wave infrared (LWIR) is a remote sensing technique that is also referred to as thermal imaging. There are two types of long wave heat sensors used to collect geothermal data. One type collects information in wavelengths between 3.0 and 5.0 micrometers (these wavelengths are actually medium range infrared but are grouped with the LWIR type surveys). Typical imaging devices used to collect data in these wavelengths are Forward Looking Infrared (FLIR) cameras. Data is usually collected from one or two bands and is used to detect relatively warm areas at the surface such as hot springs, hot pools, hot rock/lava and snow melt.[1] Another type of long wave heat sensor collects information at higher wavelengths of around 8 to 14 micrometers. These instruments can identify the signatures of some minerals such as framework silicates that may be related to hydrothermal activity.[1]
Use in Geothermal Exploration
LWIR techniques can be useful for detecting minerals such as quartz, adularia, albite, kaolinite, orthoclase, Na- and Ca-montmorillonite, calcite, opal, chalcedony, gypsum, alunite, jarosite, and other sulfates[2] and then maps can be used to show the presence of hydrothermal minerals related to geothermal activity.

Field Procedures
Instruments used to detect LWIR can be utilized from many different platforms such as hand portable, truck mounted, airborne, or satellite.[3]

Physical Properties
The electromagnetic spectrum.[4]

Best Practices
Typically, LWIR imaging as a hydrothermal exploration technique has been replaced by Hyperspectral Imaging

  1. 1.0 1.1 Katherine Young,Timothy Reber,Kermit Witherbee. 2012. Hydrothermal Exploration Best Practices and Geothermal Knowledge Exchange on Openei. In: Proceedings of the Thirty-Seventh Workshop on Geothermal Reservoir Engineering. Thirty-Seventh Workshop on Geothermal Reservoir Engineering; 2012/01/30; Stanford, CA. Stanford, CA: Stanford University, Stanford Geothermal Program; p.
  2. G.J. Scherer,D.N. Riley,W.A. Peppin,D.M. Tratt,C. Wright,K.L. Jones. 2009. Geothermal Exploration with Visible through Long Wave Infrared Imaging Spectrometers. In: Geothermal Exploration with Visible through Long Wave Infrared Imaging Spectrometers. Clean Technology Conference and Expo; 2009/05/03; Geothermal Exploration with Visible through Long Wave Infrared Imaging Spectrometers. N/A: N/A; p. N/A
  3. Karen L. Jones. 2009/01/01. Hyperspectral Remote Sensing Techniques For Locating Geothermal Resources. Poster session presented at: N/A; N/A
  4. Protherm. Infrared Basics [Internet]. 2013. [cited 2013/09/30]. Available from: http://www.pro-therm.com/infrared_basics.php

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