airminex aster minmap brochure

8/12/2019 Airminex ASTER MinMap Brochure

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---------Javier Prado Oeste 1445, Dpto 702, San Isidro Lima 27. Telfono (51-1)2216679. Telefax (51-1)221-6634---------------

AirMinEx Standard ASTER Mineral Maps

Corresponding to

INGEMMET 1:100,000-Scale Geology Series

ASTER image data have been processed for much of Peru and the resultant alteration mineralmaps have been compiled into a series of GISs in both MapInfo and Arc-GIS format covering

individual 1:100,000-scale, quarter degree quadrangles. The ASTER imagery has been used to

create a Digital Elevation Model (DEM) at a spatial resolution of 30m and this in turn has been

used to orthorectify the spectral image data. This DEM is also used to create both colour and

greyscale shaded relief images which form the lower layers of the overall GIS (Figure 1).

Figure 1; Examples of the greyscale and colour shaded reliefimages that form the base of the GIS.

Figure 2; Semi transparent geology image drapedon the greyscale shaded relief image.

An image of the geology for the quadrangle or map sheet is also imported into the GIS so that the

geology can be related to topography and structures as well as to any alteration mineralogy that

has been mapped (figure 2).

Above the DEM layers are a series of image layers representing the intensity or probability of the

presence of individual alteration minerals and general alteration styles (figure 3). The alteration

minerals mapped comprise jarosite, goethite, hematite, silica, pyrophyllite, alunite, dickite,

kaolinite, high-AlOH illite, low-AlOH illite, chlorite, epidote, dolomite and calcite and the

alteration styles mapped are ferruginous; silicic, advanced argillic, argillic, phyllic, propylitic and

carbonate. These intensity images essentially measure the closeness of match in the pixel

spectrum relative to the reference spectrum for each mineral or style and hence can be interpreted

as representing either the relative purity of the mineralogy in a pixel or the relative probability.

The lower limit of the colour scaled zones represents the level of spectral matching where there is

no evidence at all for the presence of that particular mineral or style. Vector polygon layers for

each of the mapped minerals and styles overlie all of the raster intensity layers and the limit of

each vector polygon is at the lower limit of the colour scaled raster image (figure 3).


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0% probability 100% probability

Figure 3; Intensity image for the mineral kaolinite, top

left, and the vector layer overlain top right with the

relative scaling for the intensity image bottom left.

The vector polygons for the individual minerals and alteration styles are placed in order of their

relative extents with the more extensive minerals positioned below the less extensive ones so that

all alteration minerals present in any given system may be viewed without any single layer being

obscured (figure 4).

Figure 4; All alteration mineral vector polygon layers

shown over combined shaded relief and greyscale

albedo image (top left) and combined shaded relief

and geology image (top right) with an example of the

information tool showing the assemblage at any one

point (bottom left and arrow).


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This layering also has the advantage that when any given point is queried, the entire alteration

mineral assemblage indicated for that point is revealed (figure 4). These individual mineral

distributions can then be viewed relative to one and other in terms of their intensities as well as

relative to the topography and to the geology (figure 4). Finally; additional image algorithms such

as a grey scale albedo image and the equivalent of a Landsat TM 7-4-2 rgb image are provided forpossible photo-geologic interpretive purposes along with comprehensive legends for the mineral

mapping, topography and geology (figures 5 and 6).

Figure 5; ASTER 6-3-1 rgb equivalent of the Landsat TM 7-4-2 rgb image, draped on greyscale shaded relief.

Current coverage available is shown in figure 7 and map sheets that are as yet incomplete can be

prepared in advance of our planned schedule on request and at the same price as those currently

available.


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---------Javier Prado Oeste 1445, Dpto 702, San Isidro Lima 27. Telfono (51-1)2216679. Telefax (51-1)221-6634-


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Figure 7; Current map sheets covered and planned.

The same procedures and products can also be prepared over customer-designated areas either

within a map sheet or covering a number of map sheets. Furthermore, such customized products

need not conform to map sheet boundaries. For further information and costings for such

customized products please contact us.

airminex aster minmap brochure

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