682
ground water table. These depresión area still sup
ply the water to underground during rainy season.
Because of these phenomena, density of vegetation was
employed for a denominator of paleo channel detection.
5.2 Method for vegetation density survey
Discussion to find the suitable method for vegetation
density was done between MSS band ratio 7 / 5, 7 / 4
and streched-ratioed colour composite image. Finally
MSS ratio 7/4 was chosen as the most favourable
technique to emphasize the density of vegetation in
this area.
mdst appropriate weight was given, which was, land
coverage : depth : paleo channel = 3 • 10 : 10.
The result of evaluation is shown on figure 9*
The mesh units which evaluated the highest potential
are shown in black and the second potential area is
in dots. The research and prospection for uranium
are taken place in the mining concession, the squ
are in the figure. And some of good result of the
prospection were reported from that area. Most of
the highly scored mesh units are distributed in the
mining square. From such view point it can be sum-
merized that the result of this evaluation suggest
the area where have favorable environment for urani
um deposit beneath there.
10
20
30
n /•> ^Seepage
i ry n
a
/^MS®
done, sand-
7 / // N ”
, 1 Basement rocks / A
w 'ff
■<S^V\- 'Dt t
Sedimentary '
" nocks_ •. ' ' N
' 1 ~ Ground A Basement rocks
wcjter V \
vege
tation
dense(high)
barren
dense(short)
middle
barren, non veget.
geo
logy
basement &
little sand cov
thick sand
lian)
aeo-
fine sand to
silty material
coarse sand
sand(coarse-fine),
silt
topo
graphy
gentle si.
undulation
active sand dune
small depression
depression,big&
good sucsession
sand is stable,
highly undulated
many small linear
depression
Figure 7. The relation between vegetation, geology and topography
5.3 Relation between vegetation and paleo channel
distribution
The distribution of dense vegetation zone is shown on
figure 8 (a), of which pattern is like of the river
channel. However, there are not developed any rivers
on the surface at present time. With using the bore
hole data the depth of the basement rock was analysed,
which is shown on figure 8 (b).
The basement rocks form like valley shape and the
paleo channel is developed in that valley. There are
very similar pattern of development between vegeta
tion and paleo channel, which
can be observed in map (a),
(b).
Generally the depressional
area is densely vegetated.
Occasionally the lineaments
and the sinkholes are deve
loped in there, which seem
to supply ground water to
the paleo channel even at
present time.
6 EVALUATION
Land coverage, depth thick
ness distribution of sedi
mentary rocks and the paleo
channel analysed by Landsat
imagery are employed for the
factors to evaluate the area
where are the suitable en
vironment of the uranium de
posit .
For the evaluation, we
scored these items with cer
tain weight in each mesh,
1 Km x 1 Kim. After several
time of try and error the
7 CONCLUSION
Landsat data analysis can be used for the possible
area evaluation of sedimentary uranium deposit.
However, still some technical problems are remained
on the each procedure. For instance, some part of
laterite was not identified from the basement rock,
the physical relation between surface phenomena and
geological structure is not completely made clear
yet, and so on. These ploblems can be solved in the
furture to study in comaparison with other data,
such as field survey, geophysical prospecting,boring
test, etc.
Figure 8. Comparison between pattern of vegetation distribution (a) and (b)
morphology of basement rock
123°E
\
V
□
Figure 9*
deposit
REFERENCES
Childers,
taceous
Colorado
Floyd, F.S
tation Y
Missallati
Simatler
Landsat
Remote s
Smith, A.F
ing of I
ceedings
process!
remote s
Vincent, F
-process
