10
(2.20 µm) unlike illite, which presents absorption peaks
between 0.7 µm–1.2 µm, features that coincide with the
absorption peak of the image spectra. In the evaluated area,
the highest concentration of muscovite, illite and montmo-
rillonite (Figure 11) is located south of the town of Huaten
northeast of Huaycotito and in areas that make up the
towns of Salcha, Bellavista, Coronilla and El Granero.
The spectral signature of chlorite is characterized by
absorption peaks in the ranges 1.39μm (OH), 1.98μm,
2.25μm (FeOH) and 2.32μm (Band 8). The absorption
peak in the 1.98μm range is typical of hydrated chlorites.
Calcite exhibits absorption peaks in the ranges 1.88μm,
1.99μm, 2.15μm and 2.34μm (Band 8). The spectrum
of epidote has absorption peaks in the ranges 1.55μm,
1.83μm, 1.95μm (H2O), 2.25μm (FeOH) and 2.33μm
(Band 8). The most important absorption peaks of epidote
are in the ranges 1.55μm and 1.83μm which allow it to be
differentiated from chlorite (Caiza, 2018). In Figure 9 it
can be observed that the spectral signatures, in the case of
calcite, present a strong absorption peak in the same wave-
length range corresponding to 2.32 μm -2.34 μm, a feature
that coincides with the absorption peak of the image spec-
tra, and is captured by ASTER band 8. Likewise, for chlo-
rite with an absorption peak of 2.32 μm and epidote with
2.33 μm. SAM spectral mapping indicates that there
is a higher concentration of chlorite, calcite and epidote in
the south of the Asunción district. Considering the results
obtained from the processing of the ASTER satellite image,
nine prospecting areas were defined (Figure 13).
Finally, the spectral techniques of RGB band combi-
nation, Band ratios and Ninomiya indices were compared
to each other to identify areas of interest with different
types of hydrothermal alteration that coincided or were
similar. Once these areas were identified, they were com-
pared with the results obtained from the spectral mapping
technique, in order to refine the distribution of the halos of
hydrothermal alterations, based on the typical mineralogi-
cal assemblage of each mineral deposit present within the
metallogenic bands of the study area were determined thir-
teen possible exploration targets (Figure 13).
Figure 10. Advanced Argillic Alteration Assemblages Figure 11. Argillic Phyllic Alteration Assemblages
Figure 12. Propylitic Alteration Assemblages
Figure 13. Exploration targets
(2.20 µm) unlike illite, which presents absorption peaks
between 0.7 µm–1.2 µm, features that coincide with the
absorption peak of the image spectra. In the evaluated area,
the highest concentration of muscovite, illite and montmo-
rillonite (Figure 11) is located south of the town of Huaten
northeast of Huaycotito and in areas that make up the
towns of Salcha, Bellavista, Coronilla and El Granero.
The spectral signature of chlorite is characterized by
absorption peaks in the ranges 1.39μm (OH), 1.98μm,
2.25μm (FeOH) and 2.32μm (Band 8). The absorption
peak in the 1.98μm range is typical of hydrated chlorites.
Calcite exhibits absorption peaks in the ranges 1.88μm,
1.99μm, 2.15μm and 2.34μm (Band 8). The spectrum
of epidote has absorption peaks in the ranges 1.55μm,
1.83μm, 1.95μm (H2O), 2.25μm (FeOH) and 2.33μm
(Band 8). The most important absorption peaks of epidote
are in the ranges 1.55μm and 1.83μm which allow it to be
differentiated from chlorite (Caiza, 2018). In Figure 9 it
can be observed that the spectral signatures, in the case of
calcite, present a strong absorption peak in the same wave-
length range corresponding to 2.32 μm -2.34 μm, a feature
that coincides with the absorption peak of the image spec-
tra, and is captured by ASTER band 8. Likewise, for chlo-
rite with an absorption peak of 2.32 μm and epidote with
2.33 μm. SAM spectral mapping indicates that there
is a higher concentration of chlorite, calcite and epidote in
the south of the Asunción district. Considering the results
obtained from the processing of the ASTER satellite image,
nine prospecting areas were defined (Figure 13).
Finally, the spectral techniques of RGB band combi-
nation, Band ratios and Ninomiya indices were compared
to each other to identify areas of interest with different
types of hydrothermal alteration that coincided or were
similar. Once these areas were identified, they were com-
pared with the results obtained from the spectral mapping
technique, in order to refine the distribution of the halos of
hydrothermal alterations, based on the typical mineralogi-
cal assemblage of each mineral deposit present within the
metallogenic bands of the study area were determined thir-
teen possible exploration targets (Figure 13).
Figure 10. Advanced Argillic Alteration Assemblages Figure 11. Argillic Phyllic Alteration Assemblages
Figure 12. Propylitic Alteration Assemblages
Figure 13. Exploration targets