id those 
d with 
. These 
8a. The 
  
The acidity index thus calculated does not give 
remarkable resultats. But then, its crossing with the iron 
index and raw band of TM 7 give good results. Figure 4 
is the result of crossing pictures between the two indices 
F3tm , Atm and raw band TM 7. The yellow hues, 
orange and red expresse zonation in relation with iron 
content oxides in the North East of sedimentary basin of 
Tin Serririne: Tahaggart ( Mokaddem, M., 1980b). 
  
  
  
LEGEND 
EH Desert varnish 
EN Rocky outcrop related with desert varnish 
Latentic formation of iron oxide and hydroxide - 
CI Rocky outcrop related with content iron 
  
6 Km 
(I Cover sand 
CI Other type of cover sand 
Bl Tahaggart index 
Figure 4. A Coloured Composition RGB: Iron index, Acidity index 
and TM7 (Improvement of color nuances) 
3. CONCLUSION 
In a strategic level, the establishment of the analytic 
geologic map by remote sensing of the region of In- 
Azaoua is a salient objective where the actualization the 
map of the region is possible. This allowed us to 
desengage the geologic contours of different facies where 
their outcrop with good precision. The integration of the 
thermal infrared image has proven out to be decisive. 
It is necessary to note certain difficulty to discern the 
geologic objects and this in spite rich resolution and 
spectral range that were offered by radiometers. It is 
owing mainly to the tackling desert varnish caused by 
the burgeoning eolian tending thus to dissimulate the 
spectral signatures proper of lithologic facies of different 
outcrops. In terms of cartographic geology, it is 
necessary to retain that: 
a) the cartography of lineament network was 
established by compilation of the seven bands of T.M., 
where it is necessary to note the exceptional contribution 
of thermal infrared images in the cartography of linear 
structures. Thus a structure of syn-orogenic intrusive 
granite could be disclosed in the center Hoggar, 
b) the textural aspect - in relation with the 
structural character and morphological outcrops, 
permitted a discrimination of the formations when these 
present a monotony in terms of the level of grey 
reflectance 
c) the geologic structures could be delimited 
thanks to their mode of outcrop like the case of granite 
pan-african early age in the oriental Hoggar 
At to the tactics level of the mining prospecting, the 
characterization by the thematic mapper data of the 
alteration profils of ferrugenization and kaolinization 
bound, uranium mineralization gives some pertinent 
results. 
Concerning the discrimination of the different compound 
of iron, it is necessary to note the conformity or the 
similarity of the theoretical specters of the goethites with 
regard to those some spectral curves of the samples to the 
level of contact basement - cover. 
Finally, to note that the adequacy of remote sensing to 
the different studies of geology on depends the spectral 
specificities, spatial and texturales for the facies 
searched. The lithostratigraphic wholes of our geologic 
provinces and to a least degree the cartography of 
lineament, is not all time perceptible directly. For that, 
an approach multidate of our data Thematic Mapper 
(Spring or Summer) would be desirable and where the 
International Archives of Photogrammetry and Remote Sensing. Vol. XXXII, Part 7, Budapest, 1998 605