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Remote sensing for resources development and environmental management
Damen, M. C. J.

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