International Journal of Applied Earth Observation
and Geoinformation 4 (2002) 65–74
The use of Dempster–Shafer model and GIS in integration of
geoscientific data for porphyry copper potential mapping,
north of Shahr-e-Babak, Iran
Majid Hashemi Tangestani∗ , Farid Moore
Department of Geology, Faculty of Sciences, Shiraz University, 71454 Shiraz, Iran
Received in revised form 18 October 2001; accepted 19 February 2002
Abstract
The Dempster–Shafer (D–S) belief theory, as a knowledge-driven approach for map combination, is used for porphyry
copper potential mapping, in an under-explored area, north of Shahr-e-Babak, Iran. The evidential function provides a
theoretical basis for uncertainty management in data integration in an exploration project. The results of this approach show
that strong support is found in the west-central part of the study area, where porphyry copper deposits are known. Plausibility
for the proposition is also high in the west-central parts and coincides with the zone having strong support. The uncertainty is
low in the west-central parts where there are more efficient data layers with respect to the proposition. Uncertainty is high in
the zones where either there are fewer data layers or the data cannot provide strong support for the proposition or its negation.
© 2002 Elsevier Science B.V. All rights reserved.
Keywords: Belief; Combination; Evidential function; Exploration; GIS; Knowledge-driven; Plausibility; Support; Uncertainty
1. Introduction
Exploration projects carried out in unexplored regions are mostly based on geoscientific information that
are integrated and processed by the use of GIS-based
decision making models. Although some of the mapbased approaches allow one to estimate probabilities based on known exploration target occurrences
(Bonham-Carter et al., 1988; Rencz et al., 1994; Scott,
2000), recent advances in exploration models and
decision support systems make it possible to quantify
specific map information even when there are small
∗ Corresponding author. Tel.: +98-711-2284572;
fax: +98-711-2280926.
E-mail address: tangestani@geology.susc.ac.ir
(M.H. Tangestani).
known or no target mineral occurrences in an exploration area (An et al., 1991; An, 1992; Wright and
Bonham-Carter, 1996). Because many regions in Iran
are not well-explored and only a few occurrences
or deposits are known, the Dempster–Shafer (D–S)
belief approach could be tested and evaluated for porphyry copper potential mapping and new target-area
recognition.
The D–S belief theory (Dempster, 1968; Shafer,
1976) is an alternative mechanism to the fuzzy logic
theory for knowledge representation and map combination. This method has been discussed in a mineral exploration context using a dataset (An, 1992;
An et al., 1994a,b; Chung and Fabbri, 1993; Chung
and Moon, 1991). Wright and Bonham-Carter
(1996) applied the method to combine a variety of
geophysical datasets to predict base metal and iron-
0303-2434/02/$ – see front matter © 2002 Elsevier Science B.V. All rights reserved.
PII: S 0 3 0 3 - 2 4 3 4 ( 0 2 ) 0 0 0 0 8 - 9
66
M.H. Tangestani, F. Moore / International Journal of Applied Earth Observation and Geoinformation 4 (2002) 65–74
formation deposits in an area north and west of the
Rusty Lake–Snow Lake Greenstone Belts, Manitoba,
Canada. Aminzadeh (1994) also describes the application of this model in oil exploration.
2. Belief function theory
A detailed theoretical exposition and a formalization of the belief function approach can be found
in Dempster (1968) and Shafer (1976). It is a
knowledge-driven approach (Bonham-Carter, 1994),
with some advantages and disadvantages as compared
with fuzzy logic (Zadeh, 1965). For example, one
advantage of this approach is that it allows the user
to represent uncertainty in the knowledge representation, because the interval between support (lower
belief function or a conservative estimate for a proposition) and plausibility (an optimistic assessment that
the evidence supports a proposition) can be considered as a confidence band. Missing data also could
be modeled in D–S approach by defining the plausibility as 1, the support as 0, so the uncertainty as
1. Evidences from two or more maps are combined
using Dempster’s rule of combination (Wright and
Bonham-Carter, 1996, and Eqs. (1)–(3) cited therein).
The combined support, plausibility, disbelief, and
uncertainty can each be separately mapped, although
only two of these quantities are independent. This
contrasts with the fuzzy logic output, which consists
only of a single map—the combined fuzzy membership. The output map in fuzzy model only evaluates
the favorability for porphyry copper mineralization
in various levels for the study area, but the outputs
in D–S model represent a conservative estimate of
the favorability, an optimistic estimate of favorability,
and related uncertainties in different images.
Each map to be used as evidence to evaluate a
proposition (e.g. “this cell contains a porphyry copper
deposit”) is associated with a pair of belief functions,
the support function and the plausibility function.
In practice, these functions are usually held in map
attribute tables, where each class on the map is associated with a support value and a plausibility value.
Suppose we have map A, we will simply denote the
value of the support due to A, as SupA , and the plausibility due to A, as PlsA . Because functions vary
with the value (map class) of A, they can therefore
be mapped in their own right by lookup operations
from map A. For a given value of map A, the uncertainty is denoted as UncA , calculated as PlsA − SupA ,
and the disbelief, DisA = 1 − PlsA . Thus, the sum
SupA + UncA + DisA = 1. The disbelief is the belief
that the proposition is false, i.e. that a cell does not
contain a porphyry copper deposit. Note that plausibility is greater than or equal to support. Where plausibility and support are equal, the uncertainty is zero,
and Sup + Dis = 1, as in the probability approach.
The relationship between these functions is well illustrated in Wright and Bonham-Carter (1996, Fig. 33).
For each map used as evidence, two independent
functions must be estimated, usually either the support
and disbelief, or the support and plausibility, but in
some cases, the uncertainty may be calculated with
one of the other functions values. An et al. (1994a)
and Chung and Fabbri (1993) discuss the estimation
procedure.
Given two maps A and B, with the support and disbelief functions for each, Dempster’s rule of combination for estimating the combined support, disbelief
and uncertainty are shown in Eqs. (1)–(3) (Wright and
Bonham-Carter, 1996).
SptC =
SptA SptB + SptA UncB + SptB UncA
β
(1)
DisC =
DisA DisB + DisA UncB + DisB UncA
β
(2)
UncC =
UncA UncB
β
(3)
where the denominator for all three equations is
calculated using Eq. (4):
β = 1 − SptA DisB − DisA SptB
(4)
where β is a normalizing factor that ensures that Spt+
Dis + Unc = 1.
3. Geology and mineralization
The study area (30◦ 19′ –30◦ 30′ N, and 55◦ 05′ –
55◦ 30′ E) is located north of Shahr-e-Babak town,
in SW Kerman province (Fig. 1). It is situated
within the southern part of the central Iranian
volcano–sedimentary complex. The geological evolution of the area can be simplified as formation and
M.H. Tangestani, F. Moore / International Journal of Applied Earth Observation and Geoinformation 4 (2002) 65–74
67
Fig. 1. Geological map of the study area in the north of Shahr-e-Babak, Kerman, Iran.
folding of early Tertiary volcano–sedimentary rocks,
and emplacement of late tertiary granodiorite, diorite,
monzonite and tonalite in the volcano–sedimentary
complex. A more detailed description of the geology
of an area between Rafsanjan Belt in NE to Sirjan
Belt in SW, is given by Dimitrijevic (1973).
Eocene volcano–sedimentary rocks consist of alkalibasalt–andesite flows and tuffs, and volcaniclastic
sediments. These are intersected with Pliocene and
Eocene sandstones, marls, sandy calcarenites and
conglomerates. The oldest and youngest exposures
are upper cretaceous rocks and the quaternary alluvial
deposits and gravel fans, respectively. Some well
known copper and lead–zinc deposits and occurrences
are shown in Fig. 1.
Hydrothermal alterations, mainly in the form of
chloritization, biotitization, sericitization, epidotization, carbonization, and silicification, developed in the
intrusive and the volcanic rocks, are widespread over
the area. The zonal pattern of alteration at Meiduk
is concentric and almost symmetrically arranged
around a tertiary porphyry intrusive. Potassic, phyllic,
argillic, and propylitic alterations and silicification
have been recognized at Meiduk (Amraie, 1991).
Drill core observations indicate a relatively large core
of potassic alteration surrounded by a thick shell of
phyllic alteration. Later argillic alteration has been
locally superimposed on the two earlier alteration
zones. The superimposition has occurred in places
where the surface water is driven down in contact
with suitable minerals. Argillization is more prominent and extensive at higher elevations, at surface and
especially in tunnels where acidic waters circulate
more freely. Propylitic alteration seems to be entirely
hosted by andesitic wall rocks and extends outward
for hundreds of meters around phyllic alteration zone.
Several deposits and numerous important mineral
occurrences exist in the Kerman region, among which
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M.H. Tangestani, F. Moore / International Journal of Applied Earth Observation and Geoinformation 4 (2002) 65–74
the copper deposits and occurrences are of prime
importance. Two main types of mineralization are
identified, porphyry-type and the vein-type mineralization. Porphyry-type mineralization is more important and is located in the vicinity of post-Eocene
intrusive bodies in the Eocene volcanic–sedimentary
complex. The vein-type mineralizations are controlled by faults of different trends and cut both
the intrusives and extrusives. Meiduk and Sara are
the most important porphyry copper deposits in the
region, while the Chah–Mesi is a polymetallic
deposit.
The Meiduk porphyry copper deposit, situated near
Meiduk village (Fig. 1) is hosted by Eocene andesitic
and basaltic rocks. The main intrusive body responsible for mineralization alteration at Meiduk is an epizonal dioritic porphyry stock of Oligocene to Pliocene
age (Bazin and Hubner, 1969). This deposit was mined
in ancient times and is currently mined for its porphyry
copper. The copper ore grade in the supergene zone
varies between 1 and 3%, the average being 1.52%
Cu. The supergene plus hypogene ore reserves amount
to 20 million tonnes (Geological Survey of Iran,
1973).
The Sara copper occurrence is located northwest of
Meiduk deposit (Fig. 1). The geology and mineralization is very similar to that of Meiduk. Altered dioritic
porphyrite, is exposed over an area of about 1.5 km2
and surrounded by weakly altered Eocene volcanites
and pyroclastites. Geochemical measurements indicate copper concentrations of 120–500 ppm. The exploratory drilling in the altered intrusive confirmed the
presence of porphyry-type copper mineralization. The
ore grade was low, on average about 0.15% Cu, and
no supergene enrichment was detected (Geological
Survey of Iran, 1973).
The Chah–Mesi polymetallic deposit is located at
the east of the Meiduk village (Fig. 1).The rocks of this
area are comprised of Eocene volcanic–sedimentary
complex, subvolcanic intrusive bodies of intermediate
composition, and quaternary deposits. Both volcanites and porphyrite intrusives are highly faulted and
fractured. The richest mineralization occurs along
a diagonal fault between Eocene volcanites and
diorite–porphyrite intrusives. According to Omaljev
(1972), average ore grade include 1.27% copper,
1.01% lead and 2.12% zinc with minor amounts of
silver (10–150 ppm) and gold (up to 7 ppm).
4. Data input and pre-processing
The most time-consuming step in most GIS projects
is building the database. According to variations in
data models, data structures, and data formats, the input layers may have many sizes and shapes. A digital
geoscientific data to be used in porphyry copper mineralization mapping in the study area was established.
A geological map of Shahr-e-Babak, compiled by
Geological Survey of Iran at a scale of 1:100,000 was
used as a source of lithologic and lineaments information. The bedrock geology was digitized as a series of
polygons. In order to link each polygon to a lookup
table containing attributes, a unique identifying number was given to it. There were 176 unique polygons
that were regrouped into 24 geological categories so
that each unit could be separately evaluated within
the modelling process. A generalized version of the
geological map is shown in Fig. 1.
Remotely sensed data including aeromagnetic and
Landsat Thematic Mapper (TM) were used as other
sources of information on magnetic anomalies, part of
structural features, and hydrothermal alteration haloes.
Stream sediment geochemical data consisting of
335 individual sample points were also used in the
analysis. For each sample, data on geographic coordinates, geological sheet number, and concentration of
14 elements were provided. Concentrations of six elements, (Cu, Pb, Zn, Mo, As, and Ag), were processed
and used in this study as pathfinders for porphyry
copper deposits. The raw data were run by Standard
Package for Social Sciences (SPSS) software and
basic statistics for the samples were computed. The
anomalous and background values of each element
were then calculated. Geochemical anomaly patterns
for the elements noted above were generated using the
Surfer software. The output files were then converted
into DXF format of AutoCad and imported into PC
Arc/Info to be edited and clipped for the study area.
Database for the anomalies of elements were managed using Foxpro software and the final coverages
were then converted to a raster format usable in GIS.
Linear structural features interpreted from aeromagnetic data were combined with lineaments available in
geological map to generate a lineament map. The interpreted lineaments were digitized and input into GIS
as a vector file. The lines provided in this layer were
classified and coded into four main classes according
M.H. Tangestani, F. Moore / International Journal of Applied Earth Observation and Geoinformation 4 (2002) 65–74
to their direction. A geologic expert has considered
the EW direction as a criterion for porphyry copper
occurrence in the Kerman region (Dimitrijevic, 1973).
In this form, weighting of lineament information by
direction and distance to potential copper mineralization was possible. The EW lineaments were selected,
combined with lineaments interpreted from aeromagnetic data with same direction and finally converted to
a raster format.
Porphyry copper deposits and occurrences have a
direct spatial association with granitic to intermediate plutonic rocks (Guilbert and Park, 1986). These
plutonic rocks may act as a source for the metallic
elements and/or the hydrothermal fluids responsible
for mobilizing metals. For these reasons, contacts of
appropriate intrusive bodies were considered as an
important input parameter.
To enhance the alteration haloes around intrusive
bodies, the Crósta technique for principal component
analysis (Crósta and Moore, 1989) was applied on
reflective bands of Landsat TM (Tangestani and
Moore, 2001).
Eigenvector loadings for some visible and infrared
bands of TM, (bands 1, 3, 4, 5, and 7), showed that in
each case of analysis the first principal component is
an indication for albedo, and the third for vegetation.
Features with lower importance such as iron oxides
or hydroxyls are concentrated in subsequent principal
components. PC4 of unstretched data transformation
on bands 1, 4, 5, and 7 indicate the hydroxyl bearing areas around the porphyry intrusives. Some enhanced areas coincide with present porphyry deposits, and some
indicate new exploration targets. PC4 of unstretched
data transformation on bands 1, 3, 4, and 5 indicate that iron oxide stained areas coincide with sedimentary terrains and are not suitable for exploration.
The results of principal component transformation on
stretched TM bands were relatively similar using the
unstretched bands, but the images were brighter and
the distinction between lithological units was easier.
The enhanced areas for hydroxyls were then digitized
and input into GIS as an important binary predictor.
A helicopter magnetic/electromagnetic/radiometric
(HMER) survey was flown by Geonex Aerodat
Incorporated over an area of 7000 km2 , in the Kerman province, south central part of Iran. The aim of
the project was mainly exploration of porphyry and
vein-type mineralization in the Kerman region.
69
Reford and Paterson (1994) have worked on a part
of HMER data and concluded that the porphyry copper deposits in the Kerman region are associated with
a distinct low magnetic, relative to the host rock, a
high potassium and low resistivity. The pre-processing
of aeromagnetic raster data was done previously in
the GIS department of Geological Survey of Iran. The
magnetic anomaly districts were classified in four
magnetic intensity groups. The magnetic anomaly
map, available as hard copy, was digitized and input
into the model.
5. Assigning belief function values
The assignment of belief function values for input
layers can be performed by a statistical method if an
exploration area is well surveyed and there are sufficient target occurrences. The assignments using a
statistical method is based on traditional probability
theory. When an exploration area is not well-studied,
the assignments must rely mainly on the knowledge
and expertise of exploration geologists (Wright and
Bonham-Carter, 1996).
For the study area, the assignment of the belief
function values was made subjectively for the input
maps listed in the Table 1. In practice, two problems
are encountered at this stage. The first difficulty is the
conceptualization of belief and disbelief. There is a
tendency to think of disbelief as one minus the belief.
It is often difficult to quantify an opinion indicating
the difference between disbelief and uncertainty. For
dealing with this problem, it is suggested to evaluate
the support and plausibility for the proposition, which
could readily be quantified, and to calculate the disbelief and uncertainty, using the mentioned equations
(Wright and Bonham-Carter, 1996). The second problem is that if both two maps considered for integration have large support values, the combined support
becomes close to 1. Further combination with other
maps with high support values results in values even
closer to 1 (and disbelief and uncertainty approaching
zero), making the results difficult to interpret. Assigning the low values for support as listed in Table 1 can
be suggested for dealing with this problem.
The target proposition for the north of Shahr-eBabak area is: “there is a porphyry copper deposit”.
The propositions for porphyry copper from the input
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M.H. Tangestani, F. Moore / International Journal of Applied Earth Observation and Geoinformation 4 (2002) 65–74
Table 1
Dempster–Shafer functions for each map used as evidence of
porphyry copper deposits in the north of Shahr-e-Babak, Iran
Dataset Di
Spti
Disi
Unci
Plusi
Ag concentration (ppm)
>2.6
0.25
2.4–2.6
0.20
2.2–2.4
0.15
2.0–2.2
0.10
1.8–2.0
0.05
<1.8
0.05
0.05
0.06
0.07
0.08
0.09
0.10
0.70
0.74
0.78
0.82
0.86
0.85
0.95
0.94
0.93
0.92
0.91
0.90
As concentration (ppm)
>41
0.25
37–41
0.20
33–37
0.15
29–33
0.10
<29
0.05
0.05
0.06
0.07
0.08
0.10
0.70
0.74
0.78
0.82
0.85
0.95
0.94
0.93
0.92
0.90
Cu concentration (ppm)
>150
0.30
140–150
0.25
130–140
0.20
120–130
0.15
110–120
0.10
100–110
0.05
<100
0.05
0.05
0.05
0.06
0.07
0.08
0.09
0.10
0.65
0.70
0.74
0.78
0.82
0.86
0.85
0.95
0.95
0.94
0.93
0.92
0.91
0.90
Mo concentration
>10
9–10
8–9
7–8
6–7
<6
(ppm)
0.30
0.25
0.20
0.15
0.10
0.05
0.05
0.06
0.07
0.08
0.09
0.10
0.65
0.69
0.73
0.77
0.81
0.85
0.95
0.94
0.93
0.92
0.91
0.90
Pb concentration (ppm)
>140
0.20
130–140
0.18
120–130
0.16
110–120
0.14
100–110
0.12
90–100
0.10
80–90
0.10
<80
0.05
0.05
0.06
0.06
0.07
0.08
0.09
0.10
0.10
0.75
0.76
0.78
0.79
0.80
0.81
0.80
0.85
0.95
0.94
0.94
0.93
0.92
0.91
0.90
0.90
Zn concentration (ppm)
>230
0.20
220–230
0.18
210–220
0.16
200–210
0.14
190–200
0.12
180–190
0.10
160–180
0.08
<160
0.05
0.05
0.06
0.06
0.07
0.07
0.08
0.09
0.10
0.75
0.76
0.78
0.79
0.81
0.82
0.83
0.85
0.95
0.94
0.94
0.93
0.93
0.92
0.91
0.90
Aeromagnetic data (density)
Low
0.05
Medium
0.10
0.18
0.15
0.77
0.75
0.82
0.85
Table 1 (Continued )
Dataset Di
Medium–high
High
Spti Disi Unci Plusi
0.15 0.10 0.75 0.90
0.20 0.05 0.75 0.95
Proximity to intrusive body (m)
On body
0.00–100
100–200
200–300
300–400
400–500
>500
0.25
0.22
0.20
0.18
0.15
0.10
0.05
0.05
0.06
0.07
0.08
0.10
0.12
0.15
0.70
0.72
0.73
0.74
0.75
0.78
0.80
0.95
0.94
0.93
0.92
0.90
0.88
0.85
Proximity to EW lineaments (m)
0.00–100
100–200
200–300
300–400
400–500
>500
0.15
0.12
0.10
0.08
0.06
0.05
0.05
0.08
0.10
0.15
0.18
0.20
0.80
0.80
0.80
0.77
0.76
0.75
0.95
0.92
0.90
0.85
0.82
0.80
Proximity to alteration (m)
On alteration
0.00–100
100–200
200–300
300–400
400–500
>500
0.25
0.22
0.20
0.18
0.15
0.10
0.05
0.05
0.06
0.07
0.08
0.10
0.12
0.15
0.70
0.72
0.73
0.74
0.75
0.78
0.80
0.95
0.94
0.93
0.92
0.90
0.88
0.85
Generalized geology
Red tuffs
Andesite and basalt
Volcanics
Trachyandesit and tachybasalt
Pyroclastics
Diorite
Altered rocks
Volcanic conglomerate
Tuff sandstone
Hornblend phenoandesite
Lava
Volcanic conglomerate and sandstone
0.10
0.15
0.15
0.18
0.05
0.22
0.22
0.05
0.10
0.22
0.18
0.10
0.15
0.10
0.10
0.10
0.15
0.05
0.05
0.15
0.15
0.05
0.10
0.15
0.75
0.75
0.75
0.72
0.80
0.73
0.73
0.80
0.75
0.73
0.72
0.75
0.85
0.90
0.90
0.90
0.85
0.95
0.95
0.85
0.85
0.95
0.90
0.85
maps, indicated by Di (i = 1, 2, . . . , 11), are:
Sptci = a porphyry copper deposit exists from Di .
Disci = a porphyry copper deposit does not exsits
from Di .
Uncci = 1 − Sptci − Disci .
The values of Sptci , Disci , Uncci , and Plusci
assigned to the attributes of Di , using a knowledgebased evaluation, are listed in Table 1.
M.H. Tangestani, F. Moore / International Journal of Applied Earth Observation and Geoinformation 4 (2002) 65–74
71
Fig. 2. Support map for the porphyry copper deposits at the north of Shahr-e-Babak, Iran. The ordered legend is on the basis of increasing
support. The locations of Meiduk and Sara porphyry copper deposits are also shown in this figure and in Figs. 3 and 4.
6. Interpreting output images
The belief decision support module in IDRISI for
Windows software generates three outputs, belief,
plausibility, and belief interval. The output images
are reclassified into 10 classes.
The support image (Fig. 2) represents the degree
to which the evidence provides concrete support for
the proposition. It is important to interpret it with the
plausibility and belief interval images. The plausibility image (Fig. 3) shows the degree to which the
evidence does not refute the proposition. The relationship between the two output images is significant for
evaluating what decisions to make about the gathering
information. Even if concrete evidence for a proposition is poor, i.e. belief values are low, it is still possible
to have high plausibility values in those areas. This
would suggest possible spaces where enough information exists to make a concrete decision about the use
of these spaces or the allocation of resources to them.
At the very least, it suggests where to narrow down
the selection of areas where the gathering of more
evidence seems necessary possible. The uncertainty
(Fig. 4) is the difference between plausibility and
support and acts as a measure of uncertainty about a
proposition.
The belief functions are shown in colored plots.
Fig. 2 shows the spatial distribution of the belief or
support for porphyry copper. Strong support is found
in the west-central part of the study area, where the
Meiduk and Sara porphyry copper deposits are located. A nearly strong support is also found around
the Abdar occurrence. Moderate support is extended
in two patches east of Meiduk and as an extension located to the south of Meiduk deposit. Weak support
(<5 in classified order) is found in both areas where
the datasets provide weak support for the target proposition and where there are fewer spatial data layers,
mostly at the east of area. Fig. 3 shows the spatial
distribution of plausibility, or the maximum support
for porphyry copper. Plausibility for the proposition
is high in the west-central part of the study area and
coincides with the areas with strong support. A small
area with relatively high plausibility is also found east
of the Abdar occurrence. Low plausibility are also
mainly at the east of area. The uncertainty plot (Fig. 4)
shows the degree to which the target proposition is
uncertain. The uncertainty is low in the west-central
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M.H. Tangestani, F. Moore / International Journal of Applied Earth Observation and Geoinformation 4 (2002) 65–74
Fig. 3. Plausibility map for the porphyry copper deposits to the north of Shahr-e-Babak, Iran. The ordered legend is on the basis of
increasing plausibility.
Fig. 4. Uncertainty map for the porphyry copper deposits at the north of Shahr-e-Babak. The ordered legend is on the basis of increasing
uncertainty.
M.H. Tangestani, F. Moore / International Journal of Applied Earth Observation and Geoinformation 4 (2002) 65–74
area where there are more efficient data layers with
respect to the proposition. Uncertainty is high in the
areas where either there are fewer data layers or the
data cannot provide strong support for the proposition
or its negation.
7. Conclusion
The D–S belief method is a flexible approach
which provides the possibility for representing uncertainty in the data, but the assignment of probabilities is cumbersome, e.g. in comparison to the fuzzy
model. The D–S method produces output that include
a conservative estimate of the belief (support), and
optimistic estimate of belief (plausibility), and related
uncertainties (ignorances).
The evidential belief function provides an adequate
basis to represent geoscience information. Field observations suggest that the highest plausibility and support shown in output images are well coincided on the
known deposits of the area, and some new targets are
also introduced for more detailed exploration projects.
So, it is concluded that evidential belief function theory, as a knowledge-based approach, could be a useful
model in areas such as Iran, that are not well-explored.
Although the knowledge-based data evaluation
approach using in present study relies on the knowledge and expertise of exploration geologists, it facilitates individual interpretations of Di (i = 1, 2, . . . , n)
to be pooled together and to form a set of maps
representing the target.
Acknowledgements
The authors would like to thank the research
council of Shiraz University for providing the necessary funds for this research. Dr. Alimohammadi of
the Tarbiat Modares University is also thanked for
his help in computerized methodology. The authors
would like to express their gratitude to Mr. Navaie of
Geological Survey of Iran for providing geochemical
and magnetic data for this research.
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