1/11/2012 SkyTEM USGS 2011, Colorado. "St Luis" 

 

Report # 2011_17 B 

Processing and inversion of SkyTEM data 

Client: USGS 

Colorado. Area "St Luis" 
1/11/2012 SkyTEM USGS 2011, Colorado. "St Luis" 

Table of content 

1. Introduction 

2. The SkyTEM system 

3. Processing 

4. Inversion 

5. General comments on data processing and inversion results 

6. Thematic maps and sections 

7. The Aarhus Workbench Workspace 

Appendix 1 

Appendix 2 

Appendix 3 

Appendix 4 
1/11/2012 SkyTEM USGS 2011, Colorado. "St Luis" 

1. Introduction 

This report is composed on the basis of data delivered by SkyTEM Surveys Aps 

on behalf of USGS, processed and inverted by Aarhus Geophysics Aps. The data 

is from an airborne electromagnetic geophysical surveys carried out in 

Colorado, USA, in autumn 2011. 

This report contains results from a series of flight lines acquired over few days, 

all located within the “St Luis” area (1600 line km). Another report contains the 

results from the flight lines located within the “Paradox” area. Apart from the 

actual survey, repeat testlines were also processed and inverted. 

Refer to figure 1 for a view of the location of the dataset processed. 

All coordinates are in WGS 84, UTM 13 unless otherwise stated. 

This report has been prepared by Ph.D. Andrea Viezzoli and MSc. Bjarke Roth 

from Aarhus Geophysics ApS. 
1/11/2012 SkyTEM USGS 2011, Colorado. "St Luis" 

Figure 1. Location of survey with satellite imagery 
1/11/2012 SkyTEM USGS 2011, Colorado. "St Luis" 

2. The SkyTEM system 

SkyTEM is a time-domain helicopter 

electromagnetic system designed for 

hydrogeophysical, environmental and 

mineral investigations. The system is 

shown in operation in Figure 2. The 

SkyTEM system is carried as an external 

sling load independent of the helicopter. 

The transmitter, mounted on a 

lightweight wooden lattice frame in an 

eight-sided polygon configuration, is a 

four-turn 314 m2 eight-sided loop divided 

into segments for transmitting a super 

low moment (SLM) in one turn and a 

high moment (HM) in all four turns. The 

LM is about 10 A with a turn-off time of 

about 4 μs; the HM transmits 

approximately 100 A and has a turn-off 

time of about 53.0 μs. This yields a 

maximum magnetic moment of 

approximately 120000 Am2

. 

Figure 2 The SkyTEM System 

The z-component receiver loop is placed approximately 2 m above the frame in 

what is practically a central loop configuration with a vertical offset. Two lasers 

placed on the frame measure the distance to terrain continuously and an 

inclinometer measures the tilt of the frame. Power is supplied by a generator 

placed between the helicopter and the frame. 

Measurements are carried out continuously while flying. Every single transient 

is stored in a binary format, and pre-stacked. The stack size is LM = 160 

transients/stack and HM = 64 transients/stack. Measurements cover the time 

span of 14 μs to approx. 8.84 ms from beginning of ramp down. 

Apart from GPS-, altitude- and TEM data, a number of instrument parameters 

are monitored and stored digitally so that they can be used for quality control 

when processing the data. 
1/11/2012 SkyTEM USGS 2011, Colorado. "St Luis" 

3. Processing 

The aim of processing is to prepare data for the data inversion. This includes 

data import, data corrections, filtering and culling and discarding of distorted or 

noise-filled data. The data left are then averaged spatially using trapezoid filters 

of the optimum size that allows increasing signal to noise level without 

compromising lateral resolution. Figure 3 shows the schematic workflow of the 

processing and inversion process. The processing is done using the SkyTEM 

module if the Aarhus Workbench program package. 

Figure 3. Schematic of the workflow for the data processing and inversion of SkyTEM data 

carried out with the Aarhus Workbench. 

All data are marked with a time stamp which is the key to bind information 

about current, altitude, GPS coordinates etc. During the processing a running 

mean is calculated separately for the X- and Y direction tilt data while 
1/11/2012 SkyTEM USGS 2011, Colorado. "St Luis" 

algorithms are used to automatically filter out bad altitude data - typically 

reflections from tree or bush tops. 

In this survey, the first usable time gate used for the low moment is around 14 

μs after TX has started to ramp down. Comparisons with high altitude tests 

prove that data from this gate are surely unbiased in the vast majority of the 

area. The first usable gate for the high moment is no earlier than 180 μs after 

ramp down. 

The processing of voltage data is done in a two step system: an automatic and 

a manual. In the former data is corrected for the transmitter/receiver tilt and a 

number of filters designed to cull coupled or noise influenced data is deployed. 

After that automatic processed raw soundings are inspected visually using a 

number of different data plots. At this stage it is accessed whether the filters 

have removed the right amount of data coupled to man-made infrastructures. 

It usually necessary to intervene manually to fine tune the outcome of the 

filters and obtain the most reliable results. Figure 4 shows a view of the data 

processing module of the Aarhus workbench, over a section of SkyTEM data 

from another survey, with data culled due to coupling with man-made 

structures. 

Figure 4 The data processing window of the Aarhus Workbench, showing portions of data 

deleted because of coupling with man made structures. The insert shows the corresponding 

transient in dB/dT. 

An indication of this data optimization is given in one of the QC maps in 

Appendix1.2, which provides an overview of the number of gates retained after 

all processing steps, for the whole survey. 
1/11/2012 SkyTEM USGS 2011, Colorado. "St Luis" 

Data are then averaged to increase the signal to noise ratio data using a 

trapezoid shaped averaging core, where the averaging width of late time data is 

larger than that of early time data, as seen in Figure 5. 

Figure 5. The principle behind the trapezoid shaped averaging core where data are averaged 

over larger time spans at later times to maintain as much lateral resolution as possible at early 

times while keeping a high penetration depth.

The data uncertainty for these stacked (averaged) soundings is calculated from 

the data stack. Furthermore, a minimum small uniform data uncertainty is 

assigned to all data. This uncertainty has been set to 3%. 

Soundings were taken out for every 1.5 s corresponding to approximately 30 m. 

The good signal levels at early times recorded in large portions of the survey, 

which are due to general low resistivity of the near surface layers, allowed to 

use filters as narrow as 2 s at 15 μs. Their width then it increases with depth 

reaching 15 s at 10 ms. Figure 6 summarizes the filters settings employed in 

the automated processing, before the manual editing, for low and high 

moment. 

Width1

Width2

Width3

t

Flight time

Gate 1

Gate 2

Gate n

Gate 3

Sounding

T2

T1

T3
1/11/2012 SkyTEM USGS 2011, Colorado. "St Luis" 

Figure 6. Summary of automated filters settings employed in the first part (automatic filtering) 

of the processing, for the super low (left) and high (right) moment of the SkyTEM system. 

After the automatic stacking, soundings are inspected visually using a number 

of different data plots. At this stage it is accessed whether data points at late 

times should be ascribed a higher uncertainty or removed entirely. It is custom 

to cull data when the background noise level reaches the level of the earth 

response. Assessing when data is unusable is done by looking at the decay 

curves, the noise measurements, and the distance to potential noise sources. 

This process is necessary to gain reliable model parameters in all parts of the 

data sections. Figure 7 shows one averaged sounding (transformed into late 

time apparent resistivity), with different time gates displaying different noise 

levels, for low (red) and high (green) moment. 
1/11/2012 SkyTEM USGS 2011, Colorado. "St Luis" 

Figure 7. Example of averaged sounding (transformed into late time apparent resistivity), with 

different time gates displaying different noise levels, for low (red) and high (green) moment. 
1/11/2012 SkyTEM USGS 2011, Colorado. "St Luis" 

4. Inversion 

Inversions are carried out using the quasi 3-D Spatially Constrained Inversion 

(SCI). SCI is a full non-linear damped least squares solution in which the 

transfer function of the instrumentation is modelled. This includes, among the 

others, current turn-on and -off ramps, and front gate, low pass filters system 

altitude, etc... 

The figure (Fig. 8) below shows an example of one of the geometry files, 

describing the SkyTEM system used at St Luis. 

Figure 8. Example of geometry file produced to describe the SkyTEM system deployed in 

Colorado. These files, which are flight specific, were used in the inversions for modelling the 

system transfer function. 

In the SCI scheme the model parameters are tied together spatially with a 

spatially dependent covariance which is scaled according to the distance 
1/11/2012 SkyTEM USGS 2011, Colorado. "St Luis" 

between neighbouring models. Constraining the parameters tends to enhance 

the resolution of resistivities and layer interfaces which are not well resolved in 

an independent inversion of the soundings. The flight altitude is included as an 

inversion parameter with a prior value calculated form the tilt corrected laser 

altitudes. The standard deviation on this parameter is set to 1 m. 

The SCI inversion scheme is developed for parameterized inversion with 

normally 4 layers or 5 layers and smooth inversion with e.g. 19 layers each 

having a fixed thickness, but a free resistivity (with vertical constraints). Both 

schemes have advantages. Layer interfaces, resistivities and the depth of 

penetration are best determined from the parameterized inversion. On the 

other hand, smooth inversion is more independent of the starting model and 

gradual transitions in resistivities are more conspicuous facilitating the 

delineation of complex geological structures. Inversion and inversion evaluation 

is done using the Aarhus Workbench program package. The vertical constraints 

used in the smooth models are applied to stabilize the inversion, e.g. to remove 

fictitious layers especially in models based on few data points. No a priori 

constraints on layers parameters have been used. The inversion was started 

with a homogeneous half space where the resistivity was calculated from the 

mean apparent resistivity of the sounding. The underlying inversion code is 

developed by the HydroGeophysics Group, University of Aarhus, Denmark. 

The smooth model uses fixed thickness discretized with 19 layers, but free 

resistivities. Again the resistivities were scaled according to apparent resistivity. 

Using smooth models enhances complex geological structures and are as such 

a powerful tool evaluating the complexity of the subsurface. The smooth model 

was discretized down to about 300m, with layers of logarithmically increasing 

thickness, starting from 3m. The inversion was started with a homogeneous 

half space of 50 Ohm m. 

Based on the analysis of the results of the smooth models inversion, and on 

multiple tests with different number of layers, we chose to present results from 

a 4 layers model. We use a conservative approach, having the least number of 

layers that fit the data for the entire survey satisfactorily. This ensures 

maximum sensitivity of each one of the model parameters modelled to the 

data, and therefore maximum reliability of the models. Also the few layers 

inversion was started with a homogeneous half space of 50 Ohm m. 

The depth of investigation (DOI), based on an analysis of the Jacobian matrix, 

was also calculated for the output models. This DOI, is presented in a dedicated 

horizontal map, as well as superimposed to crop the average resistivity 

horizontal maps, and as a fading of colors below the DOI on the vertical cross 

sections. the vertical cross sections. The DOI represents the maximum depth 

below surface to which there is sensitivity to the model parameters. Any model 

parameter resting much below the DOI should be disregarded. For example, 

the DOI often rests at, or close to, an interface between a conductive 

overburden and a resistive deeper layer. In this case we can conclude that the 

conductive layer does end at that interface, and it rests above a significantly 

more resistive layer, whose absolute resistive value is poorly determined. 
1/11/2012 SkyTEM USGS 2011, Colorado. "St Luis" 

Both in the smooth and few layered inversion the data fit is very good, with 

large majority of the forward responses fitting the measured data well below 

noise levels. 

In the Appendix 1 we present a number of QC geo-referenced maps of 

inversion results. 

The maps of average resistivity at different vertical intervals are given both in 

depth below ground surface and elevation above sea level. We believe that in a 

setting like this one, where topographical variations are significant, inspecting 

results only in depth below ground surface can be misleading. The maps are 

produced from the results of the smooth (19 L) inversion only. However, maps 

from the results of the 4 L inversion can be made by the client from the Aarhus 

Workbench Workspace, which can be delivered upon request (see section 7). 

Results from 4 L are however given as profiles, together with those from the 19 

L), in order to illustrate their potential usefulness. 
1/11/2012 SkyTEM USGS 2011, Colorado. "St Luis" 

5. General comments on the data processing and inversion 

results 

The signal level in the survey area is rather variable, reflecting the significant 

geological variability, which required delicate fine tuning of the width of the 

trapezoid filters. The amount of coupling to man-made structures in the area is 

limited, and the ancillary information provided in terms of GIS was adequate to 

carry out the work effectively. Fine editing of the filters characteristics was 

required to reduce the noise. 

The dataset, in some areas, contains some unusual and unexpected features in 

the high moment. There is a clear indication of external coherent noise signals 

that is not stacked out with the synchronous detection, superimposed to the 

ground response. We can identify, on the “raw” data two different effects, 

which are possibly correlated. 

The first one (see Figure 9, top panel) is a sinusoidal signal with period of 

about 4-6 s, present in middle to late time gates. The second one (Figure 10, 

top panel) has a more peculiar shape and erratic pattern, but in general terms 

it can be described as low frequency (period ranging from about 10 s up to 

several tens of s) build up and depletion of signal late times. In areas where 

the external signal adds to the ground response, the data seems not fall into 

background uncoherent noise. After different analysis that, in our opinion, 

prove that such features have no geological source, are not due to 3D effects, 

and to rule out that they could be due to variations in attitude of the frame, 

which, to a degree could have been corrected for, it was concluded that they 

probably relate to some modulation of the external signal. These 2 types of 

features, which sometimes occur over some areas, sometimes not, are 

apparent in areas of lower ground conductivity. 
1/11/2012 SkyTEM USGS 2011, Colorado. "St Luis" 

Figure 9. Example of sinusoidal-like signal in the raw HM data (top panel) superimposed to 

ground response, present in some areas of the dataset. This effect is eliminated in the 

averaged soundings (lower panel). 

Failure to remove such effects can create significant artifacts in the inversion 

output. The second one, in particular, creates an alternation of strong 

conductors and resistors at depth, which, even though may have a degree of 

spatially coherency, is not realistic in this type of geological setting. 

We tried different approaches to reduce, if not eliminate, such effects on the 

data, and in the model space, including retrieving the unstacked data, i.e., the 

really raw data. The first effect can be reduced significantly by using the 

trapezoid filters, leaving negligible effect on the outcome models, and 

producing no net loss of lateral resolution (see Figure 9, lower panel). The 

second one, due to its characteristics – high level, low, variable frequency, 

variability of affected gates, spatial variability - can’t be stacked or filtered out. 

Hence de opted for a customized removal of gates, both horizontally and 

vertically, in those stretches of the dataset where the erratic signatures were 

present (see Figure 10, lower panel). This was done with a conservative 

approach, deleting data, inverting, analysing resulting models, repeating the 

process a few times, until we were satisfied there were no significant features 

left in the models that could be linked to the above mentioned effect. This 

effect, which entailed deleting many HM late time gates, in places up to the 

middle times, caused a decrease in the DOI. See the QC map in Appendix 1.2 
1/11/2012 SkyTEM USGS 2011, Colorado. "St Luis" 

reporting the number of HM gates used in the inversion for a qualitative 

indication of areas most affected by this effect. 

Figure 10. Example of low frequency external signal affecting the late to middle gates of the HM 

raw data (top panel). In the lower panel the average data, where the effect was removed by 

deleting affected gates recursively. 

The results of the inversions are overall, satisfactory, with low residual, and 

significant lateral and vertical variations resolved. The few layers (4L) inversion, 

whose results are presented for illustrative purposes as cross sections, 

produced, locally, a misfit higher than desirable. This is due to strong lateral 

variations in the geology (i.e., fast dipping layers, or fast varying number of 

electrical layer than can be resolved). In order to avoid misleading geological 

interpretations, a line showing the data residual was superimposed to the cross 

sections. 

The results obtained from the inversion of the repeat test line acquired at 

different height show, in the surficial to intermediate part of the models, a 

degree of coherency and consistency compatible with the limited capability of 

the AEM system to resolve resistive layers. The discrepancies visible in the 

deeper part of the models are most likely due to the effect of figure 10, which, 

even though clearly present, did not affect the data from the repeated lines to 

the same degree, with the outcome that the deeper conductor to the east was 

resolved better in some cases than others. 
1/11/2012 SkyTEM USGS 2011, Colorado. "St Luis" 

6. Thematic maps and sections 

To visualize the processing and inversion results in the survey area, a number 

of theme maps and vertical sections have been made using the Aarhus 

Workbench. The colour scale for both average resistivity maps and vertical 

cross sections is a rainbow colour scale with blue as conductive and red as 

resistive. 

Theme maps include 

1. GIS maps (Appenidix 1.1) 

a. location of vertical cross sections delivered in this report 

b. topography used for processing and inversion 

2. Processing maps (Appenidix 1.2) 

a. data processed entering the inversion after decoupling 

b. number of gates used in the inversions after noise assessment 

c. number of moments used for inversion 

3. Inversion QC maps (Appenidix 1.3) 

a. inversion misfit (residual normalized to noise) 

b. depth of investigation 

c. depth of investigation (elevation) 

d. altitude variation in inversion 

4. Inversion results (Appenidix 1.4) 

a. average resistivity maps at 10 or 15 m elevation intervals 

b. average resistivity maps at varying depth intervals 

All these maps, except when stated otherwise in the legend, have been made 

using the Kriging method with a search radius of 750 m and 50 m node 

spacing, which were then smoothed to about 15 m per pixel. 

We now present a brief explanation of the key maps mentioned above, and 

their use. 

Refer to figure 1 in section 1 of the report for an overview of the location of the 

flight lines, superimposed to the satellite imagery available. 

Map 1a allows locating the geographical position of the vertical cross section, or 

profiles, presented in Appendix 2. 

Map 1b displays the topography used in the processing and inversions. 

Map 2a shows the difference between the SKyTEM soundings that entered the 

processing, and those that were used for the inversion, after the processing, 
1/11/2012 SkyTEM USGS 2011, Colorado. "St Luis" 

due to infrastructures. It is useful to appreciate how much of the EM data was 

culled during the processing due to coupling with infrastructure. 

Map 2b shows, colour-coded, the number of time gates used for the inversion 

of individual soundings. The maximum number of gates possible in this case, if 

there had been no noise on any of them, was 38 gates. However, when the 

averaged late time gates fell into noise and contain no signal, they are deleted 

and do not enter the inversion in order not to produce artefacts in the output 

models. Also galvanic coupling can affect some of the late times of both 

moments, which are deleted. Hence the spatial variability of this map. 

Map 2c shows, color-coded, the number of gates entering the inversion, after 

data processing, for each sounding. It varies from moment Low moment only, 

High Moment only, to both moments. The spatial variability of this theme is due 

to differences in coupling to man-made structures, and to geological variations 

near surface or at depth that, locally, may cause all the gates of a given 

moment to be below noise level. 

Map 3a shows, colour-coded, the spatial variation of the absolute value of the 

misfit between forward modelled data and measured data, normalized to the 

data noise for each time gate. Values lower than 1 mean that the modelled 

data fit the measured one within noise level, i.e., that the inversion fitted the 

data. Values higher than one can be due either to strong 3D effects, or to 

noisier or less accurate data. 

Maps 3b and 3c, shows colour-coded the spatial variability of the modeldependent DOI, presented in depth below surface and elevation above sea 

level. Refer to section 4 for a detailed discussion on the DOI. The colourscale 

maximum is only indicative, and does not imply that that value was expected to 

be reached in the entire area. 

Map 3d shows the variation between inversion input and output altitude. The 

higher variability of this inversion parameter in areas of more resistive cover is 

due to the lack of low moment, which determined lower sensitivity to this 

parameter. In the rest of the survey area the value is low, as expected. 

Maps 4a and 4b were masked with the Depth of Investigation, or Elevation of 

Investigation. That is, results below these surfaces where not presented and 

made transparent. 

Maps 4a present the lateral variations of resistivity, in 10 or 15 m vertical 

elevation intervals, in elevation, from proximity of topographic high down to the 

Elevation of Investigation. Maps in elevation render a clearer picture of the 

geology in those settings where the topographical variations do not match the 

deposition patterns of the underlying layers, which might have been laid out 

almost horizontally. 

Maps 4b present the lateral variations of resistivity, in vertical depth intervals of 

increasing thickness, in depth, from the surface down to the Depth of 

Investigation. Maps in depth render a clearer picture of the geology in those 

settings where the topographical variations match the deposition patterns of 

the underlying layers. 
1/11/2012 SkyTEM USGS 2011, Colorado. "St Luis" 

A number of vertical cross sections (see Appendix 2) are also shown in the 

report. They represent the projection onto a given profile of the models falling 

within a search radius of 75 m from it. The abrupt topographical variations in 

the area can determine a purely graphical incoherency in the models when 

cross cutting tie lines. Refer to Appendix 1 for their location. A copy showing 

smooth models (19 layers) and one showing parameterized models (4 layers) 

are found along with the colour scale. The cross sections are in elevation (m 

above sea level). Please note the different horizontal and vertical scales of the 

sections. 

Like for the average resistivity maps, the models have been masked with the 

DOI, which should be regarded as an indication of the depth below the 

sensitivity to the model parameters becomes too low. See section 4 for more 

thorough discussion on the DOI. 

Please refer also to the grey line representing the data misfit (residual), 

normalized against noise, to be read against the right axis. Values below 1 

mean that the measured data were fitted within noise levels. This theme is 

given to facilitate the interpretation of the results. As mentioned in section 5, 

the few layers inversion did not fit satisfactorily all the areas, due to some very 

rapid vertical variations in the 1D model (e.g., rapidly decreasing or increasing 

number of resolvable electrical layers). This produces sometimes a rapid 

localized increase in the residual in the few layers model. The models displayed 

by the 4L are then not consistent with the measured data, and should be 

disregarded. 

Appendix 3 contains the cross sections of the inversion results obtained from 

the repeat test line, flown at different heights. 
1/11/2012 SkyTEM USGS 2011, Colorado. "St Luis" 

7. The Aarhus Workbench Workspace 

Upon request, it is possible to obtain also the Workspace of the Aarhus 

Workbench which contains all the raw, edited and inverted data, the maps and 

profiles. This would allow the client to produce extra maps and profiles, and to 

inspect the entire workflow of the processing. 

Contact Aarhus Geophysics (info@aarhusgeo.com) for a copy of the 

Workspace. 
1/11/2012 SkyTEM USGS 2011, Colorado. "St Luis" 

Appendix 1.1 

The next pages contain all the horizontal maps at point 1 (GIS maps) of section 

6. Refer to section 6 for a detailed description of the different maps. 
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UTMX

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UTMY

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

10 km

 UTM Zone 13N WGS84

Profile placement on top of model positions.

Location of Profiles
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UTMX

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UTMY

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

10 km

 UTM Zone 13N WGS84

Theme gridded from SkyTEM Surveys data using Kriging with a search radius of 700 m and a cell size of 50 m.

Topography

Elevation [m.a.s.l.]
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Appendix 1.2 

The next pages contain all the horizontal maps at point 2 (Processing maps) of 

section 6. Refer to section 6 for a detailed description of the different maps. 
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UTMX

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UTMY

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

10 km

 UTM Zone 13N WGS84

Point theme where each model position either indicate discareded data or a model.

Location of Flight Lines and Models
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UTMX

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UTMY

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

10 km

 UTM Zone 13N WGS84

Point theme with the number of time gates used for the inversion of each model.

Number of Time Gates Used

Gates Used
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UTMY

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

10 km

 UTM Zone 13N WGS84

Point theme with the number of high moment time gates used for the inversion of each

model.

Number of High Moment Time Gates Used

Gates Used
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UTMX

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UTMY

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

10 km

 UTM Zone 13N WGS84

Point theme with the moments used for each model.

Moment Indication
1/11/2012 SkyTEM USGS 2011, Colorado. "St Luis" 

Appendix 1.3 

The next pages contain all the horizontal maps at point 3 (Inversion QC maps) 

of section 6. Refer to section 6 for a detailed description of the different maps. 
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UTMY

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

10 km

 UTM Zone 13N WGS84

Point theme with the data residual of each model.

Based on the Spatially Constrained Inversion of a smooth model with 19 layers.

Data Residual

Residual
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UTMY

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

10 km

 UTM Zone 13N WGS84

Point theme with the Depth of Investigation (DOI lower as a depth value) of each model.

Based on the Spatially Constrained Inversion of a smooth model with 19 layers.

Depth of Investigation (as a depth value)

Depth [m]
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UTMY

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

10 km

 UTM Zone 13N WGS84

Point theme with the Depth of Investigation (DOI lower as an elevation value) of each model.

Based on the Spatially Constrained Inversion of a smooth model with 19 layers.

Depth of Investigation (as an elevation value)

Elevation [m.a.s.l.]
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UTMY

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

10 km

 UTM Zone 13N WGS84

Point theme with the flight altitude difference (inverted - processed) of each model.

Based on the Spatially Constrained Inversion of a smooth model with 19 layers.

Flight Altitude Difference

Altitude Difference [m]
1/11/2012 SkyTEM USGS 2011, Colorado. "St Luis" 

Appendix 1.4 

The next pages contain all the horizontal maps at point 4 (Inversion results) of 

section 6. Refer to section 6 for a detailed description of the different maps. 
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UTMY

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

9 km

 UTM Zone 13N WGS84

All grids are based on the results from a Spatially Constrained Inversion made with a

smooth model with 19 layers. Maps are masked with Depth of Investigation.

Grey dots represent the location of datapoints used in the interpolation of this layer.

All themes are gridded using Kriging with a search radius of 750 m and a cell size of 50 m.

Mean Resistivity, Elevation 2510 - 2520 m.a.s.l.

Resistivity [Ohmm]
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UTMX

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UTMY

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

9 km

 UTM Zone 13N WGS84

All grids are based on the results from a Spatially Constrained Inversion made with a

smooth model with 19 layers. Maps are masked with Depth of Investigation.

Grey dots represent the location of datapoints used in the interpolation of this layer.

All themes are gridded using Kriging with a search radius of 750 m and a cell size of 50 m.

Mean Resistivity, Elevation 2500 - 2510 m.a.s.l.

Resistivity [Ohmm]
430000 435000 440000 445000 450000 455000

UTMX

4160000 4165000 4170000 4175000 4180000 4185000 4190000 4195000

UTMY

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

9 km

 UTM Zone 13N WGS84

All grids are based on the results from a Spatially Constrained Inversion made with a

smooth model with 19 layers. Maps are masked with Depth of Investigation.

Grey dots represent the location of datapoints used in the interpolation of this layer.

All themes are gridded using Kriging with a search radius of 750 m and a cell size of 50 m.

Mean Resistivity, Elevation 2490 - 2500 m.a.s.l.

Resistivity [Ohmm]
430000 435000 440000 445000 450000 455000

UTMX

4160000 4165000 4170000 4175000 4180000 4185000 4190000 4195000

UTMY

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

9 km

 UTM Zone 13N WGS84

All grids are based on the results from a Spatially Constrained Inversion made with a

smooth model with 19 layers. Maps are masked with Depth of Investigation.

Grey dots represent the location of datapoints used in the interpolation of this layer.

All themes are gridded using Kriging with a search radius of 750 m and a cell size of 50 m.

Mean Resistivity, Elevation 2480 - 2490 m.a.s.l.

Resistivity [Ohmm]
430000 435000 440000 445000 450000 455000

UTMX

4160000 4165000 4170000 4175000 4180000 4185000 4190000 4195000

UTMY

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

9 km

 UTM Zone 13N WGS84

All grids are based on the results from a Spatially Constrained Inversion made with a

smooth model with 19 layers. Maps are masked with Depth of Investigation.

Grey dots represent the location of datapoints used in the interpolation of this layer.

All themes are gridded using Kriging with a search radius of 750 m and a cell size of 50 m.

Mean Resistivity, Elevation 2470 - 2480 m.a.s.l.

Resistivity [Ohmm]
430000 435000 440000 445000 450000 455000

UTMX

4160000 4165000 4170000 4175000 4180000 4185000 4190000 4195000

UTMY

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

9 km

 UTM Zone 13N WGS84

All grids are based on the results from a Spatially Constrained Inversion made with a

smooth model with 19 layers. Maps are masked with Depth of Investigation.

Grey dots represent the location of datapoints used in the interpolation of this layer.

All themes are gridded using Kriging with a search radius of 750 m and a cell size of 50 m.

Mean Resistivity, Elevation 2460 - 2470 m.a.s.l.

Resistivity [Ohmm]
430000 435000 440000 445000 450000 455000

UTMX

4160000 4165000 4170000 4175000 4180000 4185000 4190000 4195000

UTMY

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

9 km

 UTM Zone 13N WGS84

All grids are based on the results from a Spatially Constrained Inversion made with a

smooth model with 19 layers. Maps are masked with Depth of Investigation.

Grey dots represent the location of datapoints used in the interpolation of this layer.

All themes are gridded using Kriging with a search radius of 750 m and a cell size of 50 m.

Mean Resistivity, Elevation 2450 - 2460 m.a.s.l.

Resistivity [Ohmm]
430000 435000 440000 445000 450000 455000

UTMX

4160000 4165000 4170000 4175000 4180000 4185000 4190000 4195000

UTMY

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

9 km

 UTM Zone 13N WGS84

All grids are based on the results from a Spatially Constrained Inversion made with a

smooth model with 19 layers. Maps are masked with Depth of Investigation.

Grey dots represent the location of datapoints used in the interpolation of this layer.

All themes are gridded using Kriging with a search radius of 750 m and a cell size of 50 m.

Mean Resistivity, Elevation 2440 - 2450 m.a.s.l.

Resistivity [Ohmm]
430000 435000 440000 445000 450000 455000

UTMX

4160000 4165000 4170000 4175000 4180000 4185000 4190000 4195000

UTMY

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

9 km

 UTM Zone 13N WGS84

All grids are based on the results from a Spatially Constrained Inversion made with a

smooth model with 19 layers. Maps are masked with Depth of Investigation.

Grey dots represent the location of datapoints used in the interpolation of this layer.

All themes are gridded using Kriging with a search radius of 750 m and a cell size of 50 m.

Mean Resistivity, Elevation 2430 - 2440 m.a.s.l.

Resistivity [Ohmm]
430000 435000 440000 445000 450000 455000

UTMX

4160000 4165000 4170000 4175000 4180000 4185000 4190000 4195000

UTMY

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

9 km

 UTM Zone 13N WGS84

All grids are based on the results from a Spatially Constrained Inversion made with a

smooth model with 19 layers. Maps are masked with Depth of Investigation.

Grey dots represent the location of datapoints used in the interpolation of this layer.

All themes are gridded using Kriging with a search radius of 750 m and a cell size of 50 m.

Mean Resistivity, Elevation 2420 - 2430 m.a.s.l.

Resistivity [Ohmm]
430000 435000 440000 445000 450000 455000

UTMX

4160000 4165000 4170000 4175000 4180000 4185000 4190000 4195000

UTMY

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

9 km

 UTM Zone 13N WGS84

All grids are based on the results from a Spatially Constrained Inversion made with a

smooth model with 19 layers. Maps are masked with Depth of Investigation.

Grey dots represent the location of datapoints used in the interpolation of this layer.

All themes are gridded using Kriging with a search radius of 750 m and a cell size of 50 m.

Mean Resistivity, Elevation 2410 - 2420 m.a.s.l.

Resistivity [Ohmm]
430000 435000 440000 445000 450000 455000

UTMX

4160000 4165000 4170000 4175000 4180000 4185000 4190000 4195000

UTMY

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

9 km

 UTM Zone 13N WGS84

All grids are based on the results from a Spatially Constrained Inversion made with a

smooth model with 19 layers. Maps are masked with Depth of Investigation.

Grey dots represent the location of datapoints used in the interpolation of this layer.

All themes are gridded using Kriging with a search radius of 750 m and a cell size of 50 m.

Mean Resistivity, Elevation 2400 - 2410 m.a.s.l.

Resistivity [Ohmm]
430000 435000 440000 445000 450000 455000

UTMX

4160000 4165000 4170000 4175000 4180000 4185000 4190000 4195000

UTMY

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

9 km

 UTM Zone 13N WGS84

All grids are based on the results from a Spatially Constrained Inversion made with a

smooth model with 19 layers. Maps are masked with Depth of Investigation.

Grey dots represent the location of datapoints used in the interpolation of this layer.

All themes are gridded using Kriging with a search radius of 750 m and a cell size of 50 m.

Mean Resistivity, Elevation 2390 - 2400 m.a.s.l.

Resistivity [Ohmm]
430000 435000 440000 445000 450000 455000

UTMX

4160000 4165000 4170000 4175000 4180000 4185000 4190000 4195000

UTMY

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

9 km

 UTM Zone 13N WGS84

All grids are based on the results from a Spatially Constrained Inversion made with a

smooth model with 19 layers. Maps are masked with Depth of Investigation.

Grey dots represent the location of datapoints used in the interpolation of this layer.

All themes are gridded using Kriging with a search radius of 750 m and a cell size of 50 m.

Mean Resistivity, Elevation 2380 - 2390 m.a.s.l.

Resistivity [Ohmm]
430000 435000 440000 445000 450000 455000

UTMX

4160000 4165000 4170000 4175000 4180000 4185000 4190000 4195000

UTMY

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

9 km

 UTM Zone 13N WGS84

All grids are based on the results from a Spatially Constrained Inversion made with a

smooth model with 19 layers. Maps are masked with Depth of Investigation.

Grey dots represent the location of datapoints used in the interpolation of this layer.

All themes are gridded using Kriging with a search radius of 750 m and a cell size of 50 m.

Mean Resistivity, Elevation 2370 - 2380 m.a.s.l.

Resistivity [Ohmm]
430000 435000 440000 445000 450000 455000

UTMX

4160000 4165000 4170000 4175000 4180000 4185000 4190000 4195000

UTMY

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

9 km

 UTM Zone 13N WGS84

All grids are based on the results from a Spatially Constrained Inversion made with a

smooth model with 19 layers. Maps are masked with Depth of Investigation.

Grey dots represent the location of datapoints used in the interpolation of this layer.

All themes are gridded using Kriging with a search radius of 750 m and a cell size of 50 m.

Mean Resistivity, Elevation 2360 - 2370 m.a.s.l.

Resistivity [Ohmm]
430000 435000 440000 445000 450000 455000

UTMX

4160000 4165000 4170000 4175000 4180000 4185000 4190000 4195000

UTMY

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

9 km

 UTM Zone 13N WGS84

All grids are based on the results from a Spatially Constrained Inversion made with a

smooth model with 19 layers. Maps are masked with Depth of Investigation.

Grey dots represent the location of datapoints used in the interpolation of this layer.

All themes are gridded using Kriging with a search radius of 750 m and a cell size of 50 m.

Mean Resistivity, Elevation 2350 - 2360 m.a.s.l.

Resistivity [Ohmm]
430000 435000 440000 445000 450000 455000

UTMX

4160000 4165000 4170000 4175000 4180000 4185000 4190000 4195000

UTMY

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

9 km

 UTM Zone 13N WGS84

All grids are based on the results from a Spatially Constrained Inversion made with a

smooth model with 19 layers. Maps are masked with Depth of Investigation.

Grey dots represent the location of datapoints used in the interpolation of this layer.

All themes are gridded using Kriging with a search radius of 750 m and a cell size of 50 m.

Mean Resistivity, Elevation 2340 - 2350 m.a.s.l.

Resistivity [Ohmm]
430000 435000 440000 445000 450000 455000

UTMX

4160000 4165000 4170000 4175000 4180000 4185000 4190000 4195000

UTMY

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

9 km

 UTM Zone 13N WGS84

All grids are based on the results from a Spatially Constrained Inversion made with a

smooth model with 19 layers. Maps are masked with Depth of Investigation.

Grey dots represent the location of datapoints used in the interpolation of this layer.

All themes are gridded using Kriging with a search radius of 750 m and a cell size of 50 m.

Mean Resistivity, Elevation 2330 - 2340 m.a.s.l.

Resistivity [Ohmm]
430000 435000 440000 445000 450000 455000

UTMX

4160000 4165000 4170000 4175000 4180000 4185000 4190000 4195000

UTMY

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

9 km

 UTM Zone 13N WGS84

All grids are based on the results from a Spatially Constrained Inversion made with a

smooth model with 19 layers. Maps are masked with Depth of Investigation.

Grey dots represent the location of datapoints used in the interpolation of this layer.

All themes are gridded using Kriging with a search radius of 750 m and a cell size of 50 m.

Mean Resistivity, Elevation 2320 - 2330 m.a.s.l.

Resistivity [Ohmm]
430000 435000 440000 445000 450000 455000

UTMX

4160000 4165000 4170000 4175000 4180000 4185000 4190000 4195000

UTMY

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

9 km

 UTM Zone 13N WGS84

All grids are based on the results from a Spatially Constrained Inversion made with a

smooth model with 19 layers. Maps are masked with Depth of Investigation.

Grey dots represent the location of datapoints used in the interpolation of this layer.

All themes are gridded using Kriging with a search radius of 750 m and a cell size of 50 m.

Mean Resistivity, Elevation 2310 - 2320 m.a.s.l.

Resistivity [Ohmm]
430000 435000 440000 445000 450000 455000

UTMX

4160000 4165000 4170000 4175000 4180000 4185000 4190000 4195000

UTMY

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

9 km

 UTM Zone 13N WGS84

All grids are based on the results from a Spatially Constrained Inversion made with a

smooth model with 19 layers. Maps are masked with Depth of Investigation.

Grey dots represent the location of datapoints used in the interpolation of this layer.

All themes are gridded using Kriging with a search radius of 750 m and a cell size of 50 m.

Mean Resistivity, Elevation 2300 - 2310 m.a.s.l.

Resistivity [Ohmm]
430000 435000 440000 445000 450000 455000

UTMX

4160000 4165000 4170000 4175000 4180000 4185000 4190000 4195000

UTMY

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

9 km

 UTM Zone 13N WGS84

All grids are based on the results from a Spatially Constrained Inversion made with a

smooth model with 19 layers. Maps are masked with Depth of Investigation.

Grey dots represent the location of datapoints used in the interpolation of this layer.

All themes are gridded using Kriging with a search radius of 750 m and a cell size of 50 m.

Mean Resistivity, Elevation 2290 - 2300 m.a.s.l.

Resistivity [Ohmm]
430000 435000 440000 445000 450000 455000

UTMX

4160000 4165000 4170000 4175000 4180000 4185000 4190000 4195000

UTMY

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

9 km

 UTM Zone 13N WGS84

All grids are based on the results from a Spatially Constrained Inversion made with a

smooth model with 19 layers. Maps are masked with Depth of Investigation.

Grey dots represent the location of datapoints used in the interpolation of this layer.

All themes are gridded using Kriging with a search radius of 750 m and a cell size of 50 m.

Mean Resistivity, Elevation 2280 - 2290 m.a.s.l.

Resistivity [Ohmm]
430000 435000 440000 445000 450000 455000

UTMX

4160000 4165000 4170000 4175000 4180000 4185000 4190000 4195000

UTMY

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

9 km

 UTM Zone 13N WGS84

All grids are based on the results from a Spatially Constrained Inversion made with a

smooth model with 19 layers. Maps are masked with Depth of Investigation.

Grey dots represent the location of datapoints used in the interpolation of this layer.

All themes are gridded using Kriging with a search radius of 750 m and a cell size of 50 m.

Mean Resistivity, Elevation 2270 - 2280 m.a.s.l.

Resistivity [Ohmm]
430000 435000 440000 445000 450000 455000

UTMX

4160000 4165000 4170000 4175000 4180000 4185000 4190000 4195000

UTMY

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

9 km

 UTM Zone 13N WGS84

All grids are based on the results from a Spatially Constrained Inversion made with a

smooth model with 19 layers. Maps are masked with Depth of Investigation.

Grey dots represent the location of datapoints used in the interpolation of this layer.

All themes are gridded using Kriging with a search radius of 750 m and a cell size of 50 m.

Mean Resistivity, Elevation 2260 - 2270 m.a.s.l.

Resistivity [Ohmm]
430000 435000 440000 445000 450000 455000

UTMX

4160000 4165000 4170000 4175000 4180000 4185000 4190000 4195000

UTMY

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

9 km

 UTM Zone 13N WGS84

All grids are based on the results from a Spatially Constrained Inversion made with a

smooth model with 19 layers. Maps are masked with Depth of Investigation.

Grey dots represent the location of datapoints used in the interpolation of this layer.

All themes are gridded using Kriging with a search radius of 750 m and a cell size of 50 m.

Mean Resistivity, Elevation 2245 - 2260 m.a.s.l.

Resistivity [Ohmm]
430000 435000 440000 445000 450000 455000

UTMX

4160000 4165000 4170000 4175000 4180000 4185000 4190000 4195000

UTMY

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

9 km

 UTM Zone 13N WGS84

All grids are based on the results from a Spatially Constrained Inversion made with a

smooth model with 19 layers. Maps are masked with Depth of Investigation.

Grey dots represent the location of datapoints used in the interpolation of this layer.

All themes are gridded using Kriging with a search radius of 750 m and a cell size of 50 m.

Mean Resistivity, Elevation 2230 - 2245 m.a.s.l.

Resistivity [Ohmm]
430000 435000 440000 445000 450000 455000

UTMX

4160000 4165000 4170000 4175000 4180000 4185000 4190000 4195000

UTMY

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

9 km

 UTM Zone 13N WGS84

All grids are based on the results from a Spatially Constrained Inversion made with a

smooth model with 19 layers. Maps are masked with Depth of Investigation.

Grey dots represent the location of datapoints used in the interpolation of this layer.

All themes are gridded using Kriging with a search radius of 750 m and a cell size of 50 m.

Mean Resistivity, Elevation 2215 - 2230 m.a.s.l.

Resistivity [Ohmm]
430000 435000 440000 445000 450000 455000

UTMX

4160000 4165000 4170000 4175000 4180000 4185000 4190000 4195000

UTMY

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

9 km

 UTM Zone 13N WGS84

All grids are based on the results from a Spatially Constrained Inversion made with a

smooth model with 19 layers. Maps are masked with Depth of Investigation.

Grey dots represent the location of datapoints used in the interpolation of this layer.

All themes are gridded using Kriging with a search radius of 750 m and a cell size of 50 m.

Mean Resistivity, Elevation 2200 - 2215 m.a.s.l.

Resistivity [Ohmm]
430000 435000 440000 445000 450000 455000

UTMX

4160000 4165000 4170000 4175000 4180000 4185000 4190000 4195000

UTMY

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

9 km

 UTM Zone 13N WGS84

All grids are based on the results from a Spatially Constrained Inversion made with a

smooth model with 19 layers. Maps are masked with Depth of Investigation.

Grey dots represent the location of datapoints used in the interpolation of this layer.

All themes are gridded using Kriging with a search radius of 750 m and a cell size of 50 m.

Mean Resistivity, Elevation 2185 - 2200 m.a.s.l.

Resistivity [Ohmm]
430000 435000 440000 445000 450000 455000

UTMX

4160000 4165000 4170000 4175000 4180000 4185000 4190000 4195000

UTMY

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

9 km

 UTM Zone 13N WGS84

All grids are based on the results from a Spatially Constrained Inversion made with a

smooth model with 19 layers. Maps are masked with Depth of Investigation.

Grey dots represent the location of datapoints used in the interpolation of this layer.

All themes are gridded using Kriging with a search radius of 750 m and a cell size of 50 m.

Mean Resistivity, Elevation 2170 - 2185 m.a.s.l.

Resistivity [Ohmm]
430000 435000 440000 445000 450000 455000

UTMX

4160000 4165000 4170000 4175000 4180000 4185000 4190000 4195000

UTMY

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

9 km

 UTM Zone 13N WGS84

All grids are based on the results from a Spatially Constrained Inversion made with a

smooth model with 19 layers. Maps are masked with Depth of Investigation.

Grey dots represent the location of datapoints used in the interpolation of this layer.

All themes are gridded using Kriging with a search radius of 750 m and a cell size of 50 m.

Mean Resistivity, Elevation 2155 - 2170 m.a.s.l.

Resistivity [Ohmm]
430000 435000 440000 445000 450000 455000

UTMX

4160000 4165000 4170000 4175000 4180000 4185000 4190000 4195000

UTMY

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

9 km

 UTM Zone 13N WGS84

All grids are based on the results from a Spatially Constrained Inversion made with a

smooth model with 19 layers. Maps are masked with Depth of Investigation.

Grey dots represent the location of datapoints used in the interpolation of this layer.

All themes are gridded using Kriging with a search radius of 750 m and a cell size of 50 m.

Mean Resistivity, Elevation 2140 - 2155 m.a.s.l.

Resistivity [Ohmm]
430000 435000 440000 445000 450000 455000

UTMX

4160000 4165000 4170000 4175000 4180000 4185000 4190000 4195000

UTMY

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

9 km

 UTM Zone 13N WGS84

All grids are based on the results from a Spatially Constrained Inversion made with a

smooth model with 19 layers. Maps are masked with Depth of Investigation.

Grey dots represent the location of datapoints used in the interpolation of this layer.

All themes are gridded using Kriging with a search radius of 750 m and a cell size of 50 m.

Mean Resistivity, Elevation 2125 - 2140 m.a.s.l.

Resistivity [Ohmm]
430000 435000 440000 445000 450000 455000

UTMX

4160000 4165000 4170000 4175000 4180000 4185000 4190000 4195000

UTMY

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

9 km

 UTM Zone 13N WGS84

All grids are based on the results from a Spatially Constrained Inversion made with a

smooth model with 19 layers. Maps are masked with Depth of Investigation.

Grey dots represent the location of datapoints used in the interpolation of this layer.

All themes are gridded using Kriging with a search radius of 750 m and a cell size of 50 m.

Mean Resistivity, Elevation 2110 - 2125 m.a.s.l.

Resistivity [Ohmm]
430000 435000 440000 445000 450000 455000

UTMX

4160000 4165000 4170000 4175000 4180000 4185000 4190000 4195000

UTMY

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

9 km

 UTM Zone 13N WGS84

All grids are based on the results from a Spatially Constrained Inversion made with a

smooth model with 19 layers. Maps are masked with Depth of Investigation.

Grey dots represent the location of datapoints used in the interpolation of this layer.

All themes are gridded using Kriging with a search radius of 750 m and a cell size of 50 m.

Mean Resistivity, Elevation 2095 - 2110 m.a.s.l.

Resistivity [Ohmm]
430000 435000 440000 445000 450000 455000

UTMX

4160000 4165000 4170000 4175000 4180000 4185000 4190000 4195000

UTMY

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

9 km

 UTM Zone 13N WGS84

All grids are based on the results from a Spatially Constrained Inversion made with a

smooth model with 19 layers. Maps are masked with Depth of Investigation.

Grey dots represent the location of datapoints used in the interpolation of this layer.

All themes are gridded using Kriging with a search radius of 750 m and a cell size of 50 m.

Mean Resistivity, Elevation 2080 - 2095 m.a.s.l.

Resistivity [Ohmm]
430000 435000 440000 445000 450000 455000

UTMX

4160000 4165000 4170000 4175000 4180000 4185000 4190000 4195000

UTMY

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

9 km

 UTM Zone 13N WGS84

All grids are based on the results from a Spatially Constrained Inversion made with a

smooth model with 19 layers. Maps are masked with Depth of Investigation.

Grey dots represent the location of datapoints used in the interpolation of this layer.

All themes are gridded using Kriging with a search radius of 750 m and a cell size of 50 m.

Mean Resistivity, Elevation 2065 - 2080 m.a.s.l.

Resistivity [Ohmm]
430000 435000 440000 445000 450000 455000

UTMX

4160000 4165000 4170000 4175000 4180000 4185000 4190000 4195000

UTMY

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

9 km

 UTM Zone 13N WGS84

All grids are based on the results from a Spatially Constrained Inversion made with a

smooth model with 19 layers. Maps are masked with Depth of Investigation.

Grey dots represent the location of datapoints used in the interpolation of this layer.

All themes are gridded using Kriging with a search radius of 750 m and a cell size of 50 m.

Mean Resistivity, Elevation 2050 - 2065 m.a.s.l.

Resistivity [Ohmm]
430000 435000 440000 445000 450000 455000

UTMX

4160000 4165000 4170000 4175000 4180000 4185000 4190000 4195000

UTMY

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

9 km

 UTM Zone 13N WGS84

All grids are based on the results from a Spatially Constrained Inversion made with a

smooth model with 19 layers. Maps are masked with Depth of Investigation.

Grey dots represent the location of datapoints used in the interpolation of this layer.

All themes are gridded using Kriging with a search radius of 750 m and a cell size of 50 m.

Mean Resistivity, Depth 0 - 5 m

Resistivity [Ohmm]
430000 435000 440000 445000 450000 455000

UTMX

4160000 4165000 4170000 4175000 4180000 4185000 4190000 4195000

UTMY

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

9 km

 UTM Zone 13N WGS84

All grids are based on the results from a Spatially Constrained Inversion made with a

smooth model with 19 layers. Maps are masked with Depth of Investigation.

Grey dots represent the location of datapoints used in the interpolation of this layer.

All themes are gridded using Kriging with a search radius of 750 m and a cell size of 50 m.

Mean Resistivity, Depth 5 - 10 m

Resistivity [Ohmm]
430000 435000 440000 445000 450000 455000

UTMX

4160000 4165000 4170000 4175000 4180000 4185000 4190000 4195000

UTMY

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

9 km

 UTM Zone 13N WGS84

All grids are based on the results from a Spatially Constrained Inversion made with a

smooth model with 19 layers. Maps are masked with Depth of Investigation.

Grey dots represent the location of datapoints used in the interpolation of this layer.

All themes are gridded using Kriging with a search radius of 750 m and a cell size of 50 m.

Mean Resistivity, Depth 10 - 15 m

Resistivity [Ohmm]
430000 435000 440000 445000 450000 455000

UTMX

4160000 4165000 4170000 4175000 4180000 4185000 4190000 4195000

UTMY

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

9 km

 UTM Zone 13N WGS84

All grids are based on the results from a Spatially Constrained Inversion made with a

smooth model with 19 layers. Maps are masked with Depth of Investigation.

Grey dots represent the location of datapoints used in the interpolation of this layer.

All themes are gridded using Kriging with a search radius of 750 m and a cell size of 50 m.

Mean Resistivity, Depth 15 - 20 m

Resistivity [Ohmm]
430000 435000 440000 445000 450000 455000

UTMX

4160000 4165000 4170000 4175000 4180000 4185000 4190000 4195000

UTMY

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

9 km

 UTM Zone 13N WGS84

All grids are based on the results from a Spatially Constrained Inversion made with a

smooth model with 19 layers. Maps are masked with Depth of Investigation.

Grey dots represent the location of datapoints used in the interpolation of this layer.

All themes are gridded using Kriging with a search radius of 750 m and a cell size of 50 m.

Mean Resistivity, Depth 20 - 30 m

Resistivity [Ohmm]
430000 435000 440000 445000 450000 455000

UTMX

4160000 4165000 4170000 4175000 4180000 4185000 4190000 4195000

UTMY

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

9 km

 UTM Zone 13N WGS84

All grids are based on the results from a Spatially Constrained Inversion made with a

smooth model with 19 layers. Maps are masked with Depth of Investigation.

Grey dots represent the location of datapoints used in the interpolation of this layer.

All themes are gridded using Kriging with a search radius of 750 m and a cell size of 50 m.

Mean Resistivity, Depth 30 - 40 m

Resistivity [Ohmm]
430000 435000 440000 445000 450000 455000

UTMX

4160000 4165000 4170000 4175000 4180000 4185000 4190000 4195000

UTMY

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

9 km

 UTM Zone 13N WGS84

All grids are based on the results from a Spatially Constrained Inversion made with a

smooth model with 19 layers. Maps are masked with Depth of Investigation.

Grey dots represent the location of datapoints used in the interpolation of this layer.

All themes are gridded using Kriging with a search radius of 750 m and a cell size of 50 m.

Mean Resistivity, Depth 40 - 50 m

Resistivity [Ohmm]
430000 435000 440000 445000 450000 455000

UTMX

4160000 4165000 4170000 4175000 4180000 4185000 4190000 4195000

UTMY

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

9 km

 UTM Zone 13N WGS84

All grids are based on the results from a Spatially Constrained Inversion made with a

smooth model with 19 layers. Maps are masked with Depth of Investigation.

Grey dots represent the location of datapoints used in the interpolation of this layer.

All themes are gridded using Kriging with a search radius of 750 m and a cell size of 50 m.

Mean Resistivity, Depth 50 - 60 m

Resistivity [Ohmm]
430000 435000 440000 445000 450000 455000

UTMX

4160000 4165000 4170000 4175000 4180000 4185000 4190000 4195000

UTMY

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

9 km

 UTM Zone 13N WGS84

All grids are based on the results from a Spatially Constrained Inversion made with a

smooth model with 19 layers. Maps are masked with Depth of Investigation.

Grey dots represent the location of datapoints used in the interpolation of this layer.

All themes are gridded using Kriging with a search radius of 750 m and a cell size of 50 m.

Mean Resistivity, Depth 60 - 75 m

Resistivity [Ohmm]
430000 435000 440000 445000 450000 455000

UTMX

4160000 4165000 4170000 4175000 4180000 4185000 4190000 4195000

UTMY

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

9 km

 UTM Zone 13N WGS84

All grids are based on the results from a Spatially Constrained Inversion made with a

smooth model with 19 layers. Maps are masked with Depth of Investigation.

Grey dots represent the location of datapoints used in the interpolation of this layer.

All themes are gridded using Kriging with a search radius of 750 m and a cell size of 50 m.

Mean Resistivity, Depth 75 - 90 m

Resistivity [Ohmm]
430000 435000 440000 445000 450000 455000

UTMX

4160000 4165000 4170000 4175000 4180000 4185000 4190000 4195000

UTMY

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

9 km

 UTM Zone 13N WGS84

All grids are based on the results from a Spatially Constrained Inversion made with a

smooth model with 19 layers. Maps are masked with Depth of Investigation.

Grey dots represent the location of datapoints used in the interpolation of this layer.

All themes are gridded using Kriging with a search radius of 750 m and a cell size of 50 m.

Mean Resistivity, Depth 90 - 105 m

Resistivity [Ohmm]
430000 435000 440000 445000 450000 455000

UTMX

4160000 4165000 4170000 4175000 4180000 4185000 4190000 4195000

UTMY

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

9 km

 UTM Zone 13N WGS84

All grids are based on the results from a Spatially Constrained Inversion made with a

smooth model with 19 layers. Maps are masked with Depth of Investigation.

Grey dots represent the location of datapoints used in the interpolation of this layer.

All themes are gridded using Kriging with a search radius of 750 m and a cell size of 50 m.

Mean Resistivity, Depth 105 - 120 m

Resistivity [Ohmm]
430000 435000 440000 445000 450000 455000

UTMX

4160000 4165000 4170000 4175000 4180000 4185000 4190000 4195000

UTMY

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

9 km

 UTM Zone 13N WGS84

All grids are based on the results from a Spatially Constrained Inversion made with a

smooth model with 19 layers. Maps are masked with Depth of Investigation.

Grey dots represent the location of datapoints used in the interpolation of this layer.

All themes are gridded using Kriging with a search radius of 750 m and a cell size of 50 m.

Mean Resistivity, Depth 120 - 140 m

Resistivity [Ohmm]
430000 435000 440000 445000 450000 455000

UTMX

4160000 4165000 4170000 4175000 4180000 4185000 4190000 4195000

UTMY

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

9 km

 UTM Zone 13N WGS84

All grids are based on the results from a Spatially Constrained Inversion made with a

smooth model with 19 layers. Maps are masked with Depth of Investigation.

Grey dots represent the location of datapoints used in the interpolation of this layer.

All themes are gridded using Kriging with a search radius of 750 m and a cell size of 50 m.

Mean Resistivity, Depth 140 - 160 m

Resistivity [Ohmm]
430000 435000 440000 445000 450000 455000

UTMX

4160000 4165000 4170000 4175000 4180000 4185000 4190000 4195000

UTMY

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

9 km

 UTM Zone 13N WGS84

All grids are based on the results from a Spatially Constrained Inversion made with a

smooth model with 19 layers. Maps are masked with Depth of Investigation.

Grey dots represent the location of datapoints used in the interpolation of this layer.

All themes are gridded using Kriging with a search radius of 750 m and a cell size of 50 m.

Mean Resistivity, Depth 160 - 180 m

Resistivity [Ohmm]
430000 435000 440000 445000 450000 455000

UTMX

4160000 4165000 4170000 4175000 4180000 4185000 4190000 4195000

UTMY

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

9 km

 UTM Zone 13N WGS84

All grids are based on the results from a Spatially Constrained Inversion made with a

smooth model with 19 layers. Maps are masked with Depth of Investigation.

Grey dots represent the location of datapoints used in the interpolation of this layer.

All themes are gridded using Kriging with a search radius of 750 m and a cell size of 50 m.

Mean Resistivity, Depth 180 - 200 m

Resistivity [Ohmm]
430000 435000 440000 445000 450000 455000

UTMX

4160000 4165000 4170000 4175000 4180000 4185000 4190000 4195000

UTMY

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

9 km

 UTM Zone 13N WGS84

All grids are based on the results from a Spatially Constrained Inversion made with a

smooth model with 19 layers. Maps are masked with Depth of Investigation.

Grey dots represent the location of datapoints used in the interpolation of this layer.

All themes are gridded using Kriging with a search radius of 750 m and a cell size of 50 m.

Mean Resistivity, Depth 200 - 220 m

Resistivity [Ohmm]
430000 435000 440000 445000 450000 455000

UTMX

4160000 4165000 4170000 4175000 4180000 4185000 4190000 4195000

UTMY

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

9 km

 UTM Zone 13N WGS84

All grids are based on the results from a Spatially Constrained Inversion made with a

smooth model with 19 layers. Maps are masked with Depth of Investigation.

Grey dots represent the location of datapoints used in the interpolation of this layer.

All themes are gridded using Kriging with a search radius of 750 m and a cell size of 50 m.

Mean Resistivity, Depth 220 - 240 m

Resistivity [Ohmm]
430000 435000 440000 445000 450000 455000

UTMX

4160000 4165000 4170000 4175000 4180000 4185000 4190000 4195000

UTMY

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

9 km

 UTM Zone 13N WGS84

All grids are based on the results from a Spatially Constrained Inversion made with a

smooth model with 19 layers. Maps are masked with Depth of Investigation.

Grey dots represent the location of datapoints used in the interpolation of this layer.

All themes are gridded using Kriging with a search radius of 750 m and a cell size of 50 m.

Mean Resistivity, Depth 240 - 260 m

Resistivity [Ohmm]
430000 435000 440000 445000 450000 455000

UTMX

4160000 4165000 4170000 4175000 4180000 4185000 4190000 4195000

UTMY

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

9 km

 UTM Zone 13N WGS84

All grids are based on the results from a Spatially Constrained Inversion made with a

smooth model with 19 layers. Maps are masked with Depth of Investigation.

Grey dots represent the location of datapoints used in the interpolation of this layer.

All themes are gridded using Kriging with a search radius of 750 m and a cell size of 50 m.

Mean Resistivity, Depth 260 - 280 m

Resistivity [Ohmm]
430000 435000 440000 445000 450000 455000

UTMX

4160000 4165000 4170000 4175000 4180000 4185000 4190000 4195000

UTMY

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

9 km

 UTM Zone 13N WGS84

All grids are based on the results from a Spatially Constrained Inversion made with a

smooth model with 19 layers. Maps are masked with Depth of Investigation.

Grey dots represent the location of datapoints used in the interpolation of this layer.

All themes are gridded using Kriging with a search radius of 750 m and a cell size of 50 m.

Mean Resistivity, Depth 280 - 300 m

Resistivity [Ohmm]
430000 435000 440000 445000 450000 455000

UTMX

4160000 4165000 4170000 4175000 4180000 4185000 4190000 4195000

UTMY

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

9 km

 UTM Zone 13N WGS84

All grids are based on the results from a Spatially Constrained Inversion made with a

smooth model with 19 layers. Maps are masked with Depth of Investigation.

Grey dots represent the location of datapoints used in the interpolation of this layer.

All themes are gridded using Kriging with a search radius of 750 m and a cell size of 50 m.

Mean Resistivity, Depth 280 - 300 m

Resistivity [Ohmm]
1/11/2012 SkyTEM USGS 2011, Colorado. "St Luis" 

Appendix 2 

The next pages contain the vertical resistivity profiles, for both the few and the 

multi layers inversion, with DOI superimposed to them. Refer to Appendix 1.1 

for a map of the locations of the profiles. Profiles are drawn West to East. 

Notice that the discontinuities in topography visible in some profiles are due to 

models belonging to tie lines projected onto the profile. 
N-S 01S

N-S 01L

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

The upper cross sections show 1D modelbars from the Spatially Constrained Inversion based on a smooth model with 19 layers.

The lower cross section show the similar result based on a layered model with 4 layers.

The colors are faded below the Depth of Investigation (DOI lower).

The grey lines show the data residual normalized against noise.

Cross Sections with 1D Modelbars

Resistivity [Ohmm]
NW-SE 01S

NW-SE 01L

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

The upper cross sections show 1D modelbars from the Spatially Constrained Inversion based on a smooth model with 19 layers.

The lower cross section show the similar result based on a layered model with 4 layers.

The colors are faded below the Depth of Investigation (DOI lower).

The grey lines show the data residual normalized against noise.

Cross Sections with 1D Modelbars

Resistivity [Ohmm]
NW-SE 02S

NW-SE 02L

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

The upper cross sections show 1D modelbars from the Spatially Constrained Inversion based on a smooth model with 19 layers.

The lower cross section show the similar result based on a layered model with 4 layers.

The colors are faded below the Depth of Investigation (DOI lower).

The grey lines show the data residual normalized against noise.

Cross Sections with 1D Modelbars

Resistivity [Ohmm]
NW-SE 03S

NW-SE 03L

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

The upper cross sections show 1D modelbars from the Spatially Constrained Inversion based on a smooth model with 19 layers.

The lower cross section show the similar result based on a layered model with 4 layers.

The colors are faded below the Depth of Investigation (DOI lower).

The grey lines show the data residual normalized against noise.

Cross Sections with 1D Modelbars

Resistivity [Ohmm]
SW-NE 01S

SW-NE 01L

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

The upper cross sections show 1D modelbars from the Spatially Constrained Inversion based on a smooth model with 19 layers.

The lower cross section show the similar result based on a layered model with 4 layers.

The colors are faded below the Depth of Investigation (DOI lower).

The grey lines show the data residual normalized against noise.

Cross Sections with 1D Modelbars

Resistivity [Ohmm]
SW-NE 02S

SW-NE 02L

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

The upper cross sections show 1D modelbars from the Spatially Constrained Inversion based on a smooth model with 19 layers.

The lower cross section show the similar result based on a layered model with 4 layers.

The colors are faded below the Depth of Investigation (DOI lower).

The grey lines show the data residual normalized against noise.

Cross Sections with 1D Modelbars

Resistivity [Ohmm]
SW-NE 03S

SW-NE 03L

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

The upper cross sections show 1D modelbars from the Spatially Constrained Inversion based on a smooth model with 19 layers.

The lower cross section show the similar result based on a layered model with 4 layers.

The colors are faded below the Depth of Investigation (DOI lower).

The grey lines show the data residual normalized against noise.

Cross Sections with 1D Modelbars

Resistivity [Ohmm]
SW-NE 04S

SW-NE 04L

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

The upper cross sections show 1D modelbars from the Spatially Constrained Inversion based on a smooth model with 19 layers.

The lower cross section show the similar result based on a layered model with 4 layers.

The colors are faded below the Depth of Investigation (DOI lower).

The grey lines show the data residual normalized against noise.

Cross Sections with 1D Modelbars

Resistivity [Ohmm]
SW-NE 05S

SW-NE 05L

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

The upper cross sections show 1D modelbars from the Spatially Constrained Inversion based on a smooth model with 19 layers.

The lower cross section show the similar result based on a layered model with 4 layers.

The colors are faded below the Depth of Investigation (DOI lower).

The grey lines show the data residual normalized against noise.

Cross Sections with 1D Modelbars

Resistivity [Ohmm]
SW-NE 06S

SW-NE 06L

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

The upper cross sections show 1D modelbars from the Spatially Constrained Inversion based on a smooth model with 19 layers.

The lower cross section show the similar result based on a layered model with 4 layers.

The colors are faded below the Depth of Investigation (DOI lower).

The grey lines show the data residual normalized against noise.

Cross Sections with 1D Modelbars

Resistivity [Ohmm]
SW-NE 07S

SW-NE 07L

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

The upper cross sections show 1D modelbars from the Spatially Constrained Inversion based on a smooth model with 19 layers.

The lower cross section show the similar result based on a layered model with 4 layers.

The colors are faded below the Depth of Investigation (DOI lower).

The grey lines show the data residual normalized against noise.

Cross Sections with 1D Modelbars

Resistivity [Ohmm]
SW-NE 08S

SW-NE 08L

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

The upper cross sections show 1D modelbars from the Spatially Constrained Inversion based on a smooth model with 19 layers.

The lower cross section show the similar result based on a layered model with 4 layers.

The colors are faded below the Depth of Investigation (DOI lower).

The grey lines show the data residual normalized against noise.

Cross Sections with 1D Modelbars

Resistivity [Ohmm]
SW-NE 09S

SW-NE 09L

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

The upper cross sections show 1D modelbars from the Spatially Constrained Inversion based on a smooth model with 19 layers.

The lower cross section show the similar result based on a layered model with 4 layers.

The colors are faded below the Depth of Investigation (DOI lower).

The grey lines show the data residual normalized against noise.

Cross Sections with 1D Modelbars

Resistivity [Ohmm]
SW-NE 10S

SW-NE 10L

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

The upper cross sections show 1D modelbars from the Spatially Constrained Inversion based on a smooth model with 19 layers.

The lower cross section show the similar result based on a layered model with 4 layers.

The colors are faded below the Depth of Investigation (DOI lower).

The grey lines show the data residual normalized against noise.

Cross Sections with 1D Modelbars

Resistivity [Ohmm]
SW-NE 11S

SW-NE 11L

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

The upper cross sections show 1D modelbars from the Spatially Constrained Inversion based on a smooth model with 19 layers.

The lower cross section show the similar result based on a layered model with 4 layers.

The colors are faded below the Depth of Investigation (DOI lower).

The grey lines show the data residual normalized against noise.

Cross Sections with 1D Modelbars

Resistivity [Ohmm]
W-E 01S

W-E 01L

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

The upper cross sections show 1D modelbars from the Spatially Constrained Inversion based on a smooth model with 19 layers.

The lower cross section show the similar result based on a layered model with 4 layers.

The colors are faded below the Depth of Investigation (DOI lower).

The grey lines show the data residual normalized against noise.

Cross Sections with 1D Modelbars

Resistivity [Ohmm]
W-E 02S

W-E 02L

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

The upper cross sections show 1D modelbars from the Spatially Constrained Inversion based on a smooth model with 19 layers.

The lower cross section show the similar result based on a layered model with 4 layers.

The colors are faded below the Depth of Investigation (DOI lower).

The grey lines show the data residual normalized against noise.

Cross Sections with 1D Modelbars

Resistivity [Ohmm]
W-E 03S

W-E 03L

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

The upper cross sections show 1D modelbars from the Spatially Constrained Inversion based on a smooth model with 19 layers.

The lower cross section show the similar result based on a layered model with 4 layers.

The colors are faded below the Depth of Investigation (DOI lower).

The grey lines show the data residual normalized against noise.

Cross Sections with 1D Modelbars

Resistivity [Ohmm]
W-E 04S

W-E 04L

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

The upper cross sections show 1D modelbars from the Spatially Constrained Inversion based on a smooth model with 19 layers.

The lower cross section show the similar result based on a layered model with 4 layers.

The colors are faded below the Depth of Investigation (DOI lower).

The grey lines show the data residual normalized against noise.

Cross Sections with 1D Modelbars

Resistivity [Ohmm]
1/11/2012 SkyTEM USGS 2011, Colorado. "St Luis" 

Appendix 3 

The next pages contain the vertical resistivity profiles, for the repeat test line, 

flown at different heights. 
Pass 1

Pass 2

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

Inversion results from the test line flown at different fligth altitudes.

The colors are faded below the Depth of Investigation (DOI lower).

Cross Sections with 1D Modelbars

Resistivity [Ohmm]
Pass 3

Pass 4

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

Inversion results from the test line flown at different fligth altitudes.

The colors are faded below the Depth of Investigation (DOI lower).

Cross Sections with 1D Modelbars

Resistivity [Ohmm]
Pass 5

Pass 6

SkyTEM Survey Colorado, "San Luis". Report # 2011_17 B

Client: USGS

Inversion results from the test line flown at different fligth altitudes.

The colors are faded below the Depth of Investigation (DOI lower).

Cross Sections with 1D Modelbars

Resistivity [Ohmm]
1/11/2012 SkyTEM USGS 2011, Colorado. "St Luis" 

Appendix 4 

CD/DVD containing thematic maps, report, inversion results in ASCII format, 

processing and inversion settings. In alternative, the data is provided via secure 

ftp connection. Please contact av@aarhusgeo.com for details about the 

connection.