Full text: Remote sensing for resources development and environmental management (Volume 2)

also be used to examine intraclass variability, to 
examine how separability may change with an 
increase or decrease in the number of channels 
utilized, and to determine the spectral channels 
most useful for classifying specific class pairs. 
The transformed divergence analysis identified the 
optimum subset of two MSS bands as bands 5 (.5 to 
.6 ;jm) and 7 (.8 to 1.1 /am). Note that the selected 
bands are those that have been generally recommended 
for geologic analysis. The transformed divergence 
algorithms allow the analyst to determine if infor 
mation classes are spectrally unique or should be 
modified by merging or deleting classes. 
The resulting classification of rock types (not ill 
ustrated here), based on the procedures described 
above, is estimated to be about 80% accurate based on 
field data. 
The major structural elements of the southcentral 
Alborz Mountains are faults. These faults trend 
east-west, causing the Precambrian formations drop 
from the height of Alam Kuh (4800 m) to an unknown 
depth below Kavir plain (Asserto, 1966, Stocklin, 
The fracture traces of Qazvin Plain located near the 
far west boundary of the study area are typical 
expressions of such structure and trend ESE to WNW 
parallel to the main trends of the area. Some east- 
striking structural elements interfere with this 
strike direction and are visible in the southern 
border of Alborz Mountains. It is postulated that 
the interplay of these trends contributed to the 
occurrence of Boyin Earthquake. 
Topographic lineaments are additional features 
depicted on Landsat scene of the study area. They 
are characterized by the alignment of topographic 
features and tonal alignments indicated by specific 
soil, moisture, vegetation and relief. 
On the basis of analysis of the enhanced Landsat MSS 
images of the study area, most of the topographic 
lineaments, faults, and other lineaments seem to be 
related to a system of compressional stress that 
extends from the south or central Iranian Plateau to 
the north. The tectonic activity along this stress 
zone has been going on since Cretaceous time 
(Stocklin, 1974). The most recent activity was 
manifested by numerous earthquakes, suggesting that 
the evolution of the range is still in progress. 
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The small scale of Landsat images makes the alignment 
of individual features across large areas more 
obvious. Within the study area there are several 
lineaments that possess characteristics normally 
associated with faults, which are classified as such 
and marked by names (Figure 3). The main fault 
traces correspond to Kandovan, Garmabdar, Fasham- 
Musha and Tuchal-Karaj faults. These fault traces 
appear on the enhanced Landsat images as terrain 
scars, and are easily recognizable over a distance of 
many kilometers. The continuity of the Garmabdar 
Fault, particularly at its western end, is surprising 
when compared with information previously acquired. 
On a geology map (Asserto, 1966), the location of the 
Garmabdar Fault is in part assumed, and shows a bend 
toward north that can be confirmed by examination of 
the Landsat images. 
Despite the linearity of the Fasham-Musha Thrust, 
there are minor bends in the fault that may, in fact, 
be small offsets at its intersection with several 
small transverse faults. This suggests that tectonic 
forces have continued to be active in recent times. 
Based on geological mapping, this lineament is the 
trace of a high angle fault, with evidence of fault 
breccia and stratigraphic displacement on the ground. 
It is clearly depicted on the Landsat MSS images that 
all the fold axes here are parallel to the trace of 
this thrust. In addition to the trace of the fault, 
the outline of Shahrestanak Klippe, a calcareous 
allochthonous, mass is traceable. 
In the case of Tuchal-Karaj Upthrust, the line of 
structure seems to be fairly clear indication of a 
thrust marking the Alborz front as a continuous scar. 
The trace of this thrust is marked by springs and 
patches of vegetation that appear in dark tone on the 
Landsat images. This fault separates the gentle 
morphology of short ridges and elongated hills to its 
southern side from the intensity folded zone to its 
northern side. 
In addition to fault lineaments, several fracture 
zones were identified on the enhanced Landsat imagery 
of the study area. These features include linear 
features attributable to terrain discontinuities that 
are arranged in sets having a common orientation. 
The identification of previously unknown lineaments 
and fracture systems has been a major contribution of 
Landsat image analysis in mineral exploration and the 
identification of earthquake occurrences. Indica 
tions of the relationship between lineaments and 
zones of seismic activities, as well as mineral 
ization areas, can be detected by comparative 
analysis of lineament maps, maps of the regional 
distribution of mineral deposits, and epicenter maps 
of historical earthquakes. 
The detection of such information on Landsat imagery 
could provide a better understanding of seismic risk 
hazards or mineral concentration locations for reg 
ional development schemes. The information derived 
from an analysis of lineament concentrations can 
indicate where the crust is the weakest and, there 
fore, most likely to be mineralized or susceptible to 
seismic activity. 
For the purpose of this study, overlays were prepared 
depicting (1) the occurrence of phosphate deposits 
and (2) the epicenters of historic earthquakes within 
the study area. These overlays were compared with 
the orientation of the lineaments interpreted from 
enhanced and classified Landsat images. 
A correlation was found between the distribution of 
phosphate deposits in central Alborz (Geological 
Survey of Iran, 1974), and lineament trends expressed 
on the Landsat images. The comparison also demon 
strated the dependence of seismically active zones on 
the regional structural features and showed a good 
agreement between the general distribution of epi 
centers and active faults. 
The significance of these correlations in future 
mineral exploration and earthquake risk hazard 
assessment is of invaluable importance. 
Landsat images are being used operationally in the 
completion of geologic maps of different parts of the 
world. Geologic maps based on Landsat-derived 
information are especially useful in providing 
Gansser, i 
Petr. M: 
11, Tehi 
Haack, B.l 
Pohn, H.A. 
logic I 
Siegal, B. 
of Iran, 
Remote S 
American S 
Remote S

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