Table 2. Spectral and spatial requirements for sediment-hosted precious metal deposits. 
  
  
CHARACTERISTIC DESCRIPTION SPECTRAL RANGE (um) SPATIAL RES.(m) 
Multispec. Hyperspec.* Recon Deposit Scale 
Primary Alterat.** ^ Narrow jasperoid and 2.15-2.35 9.7, 2.19& 15-30 5-8 
silica, weak illite, kaol., 9.5-10.5 2.34, 2.21, 
montmorill., decalcif., 2.33 
distal ammonium silic. 
Secondary Alterat. ^ Weak jarosite, goethite 0.6-0.7, 0.9, 0.95 10-30 5-8 
0.8-1.0 
Host Rocks Calcareous carbonaceous VNIR,SWIR 2.33,9.7 20-30 10-20 
fine-grained sediments, 9.5-10.5 
shale, limestone, sandstn. 
Zoning *** Silicification-illite-less 9.5-10.5, 9.7, 2.19, 10-20 4-6 
ordered illite-kaolinite 2.15-2.35 2.21 
Structure High-angle regional normal VNIR, SWIR,  Spect. feat. 20-80 10-20 
faults, regional anticlines, Microwave, listed above 
local normal faults TIR 
Vegetation Decrease over silicified knobs NIR 0.7-0.8 10-20 5-8 
and ridges and clay altered 
zones in semiarid climates 
* Position of some key absorption maxima and emission minima. 
** Alteration is weak and aerially restricted. Anomalies are subtle. Sophisticated enhancement techniques 
and multiple indicators may be required for detection. 
*** From core outward to fringe. Ore common beyond silicification within the inner argillic zone. 
  
  
Table 3. Spectral and spatial requirements for the volcanic-hosted deposits, high sulfidation subtype, 
including hot spring, maar, and porphyry gold deposits. 
  
  
CHARACTERISTIC DESCRIPTION SPECTRAL RANGE(um) SPATIAL RES.(m) 
Multispec. — Hyperspec. * Recon Deposit Scale 
Primary Alteration** Silica, alunite, pyrophyllite, 2.15-2.35 9,7,2:18,; 20-30 5-8 
kaolinite, chlorite, pyrite, 9.5-10.5 2.21, 2.36, 
illite, (montmorill.),propylitic, 2.19&2.34, 
ammonium, carbonates 2:1;2.33 
Secondary Alterat. Jarosite, goethite, hematite 0.6-0.7, 0.9, 0.95, 20-30 5-8 
0.8-1.0 8.5 
Host Rocks Rhyolitic to andesitic flows & VNIR,TIR TIR bands 20-30 10-20 
breccia, tuffac.lacust.seds, SWIR 
hypab.porphyries 
Zoning*** Silica-alunite/pyrophyllite- 9.5-10.5 9772.18 20-30 5-8 
(advanced argillic), kaolinite 2.15-2.35 2.212.36, 
& chlorite (intermediate 2.19:2.33 
argillic), illite, propylitic 
Structure Caldera ring and radial fract., VNIR, TIR, Spectral feat. 20-80 10-20 
high angle faults, grabbens, SWIR, above 
local fract.zones, maars,domes Microwave 
Vegetation Decrease over silicified and NIR 0.7-0.8 20-30 5-8 
clay altered zones (annular) 
* Seetable 2. ** Alteration is intense and aerially extensive. *** From core outward to broad propylitic zone. 
——À 
642 
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B7. Vienna 1996