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S2Je9NE*et2 CLAW LAKE
RECEIVED010 JUL 1 l 19/7
MINING LANDS SECTIO.V
A COMPARISON OF AN AIRBORNE
GAMMA-RAY SPECTROMETRY ANOMALY
WITH GROUND FOLLOW-UP SURVEY
RESULTS IN THE CLAW LAKE AREA
BARRIE F. JOSE
Queen's University, Kingston, Ontario. 1977.
a thesis submitted in partial fulfillment for the degree of B.Se. Honours, Geophysics.
ABSTRACT
The Geological Survey of Canada and Atonic Energy of Canada
Ltd. have produced a high sensitivity gamma-ray spectrometer for
airborne radiometric mapping of the Canadian Shield, Airborne
data collected with the system in northern Ontario during the
summer of 1975 indicated very anomalous values in the area off.
Claw Lake. A Oetailled ground study involving geological tapping
and ground scintillometer surveys within a group of 12 contiguous
claims was compared with the airborne profiles and contour nap*.
Most of the area is covered with glacial overburden and the
few granitic outcrops within the claim-group did not possess
unusually high count rates. Some of the highest*reading ample*
from outcrops were assayed for U,O., ThO., and K and the ResultsJo 2
were found to be very low. The hills of boulders and boulder field*
within the claim-group may have provided an important contribution
to the anomalous signal. It is likely that the boulder* are a lag, . . . ( .t . , s
deposit resulting from the removal of finer detritial material by
glacial meltwater.
Variations in terrain clearance, changes in the temperature
of the photomultiplier tubes and temporary radiation sources such214 i as cosmic ray bursts, atmospheric Bi, andavnthetic particle*
in the atmosphere do not provide a satisfactory explanation of the -. "
anomaly. The possibility that the principal source lies north of the
claim-group is supported by the airborne profiles, aeromagnetic
data, and the possibility of a fault or shear zone along a lineament
north of the property. Correlation between airborne and ground
data in the area of the claim-group is very poor.
C
ACKNOWLEDGEMENTS
The author is most grateful to his adviser, Dr. E. Farrar,
for his invaluable advice and critical reading of the original
manuscript.
My sincere thanks are extended to Noranda Exploration Company, Limited through Dr. R.S. Woolverton, who made the field
study possible, and Mrs. S. Dublin for her assistance in
preparation of the final copy.I would especially like to thank Miss J. Murray for her very
capable assistance in the field work.
/ o /\abJi W**f\,et- tov
J. l l. Jin got-nO/ /t+rftlff
TABLE OF CONTENTS
ftf)
5aje9NEwi2 CLAW LAKE 010CABSTRACT
ACKNOWLEDGEMENTS
TABLE OF CONTENTS
LIST OF FIGURES, TABLES, AND MAPS
INTRODUCTION
PART A-REVIEW OF AIRBORNE THEORY
INTRODUCTION
l SOURCES OF RADIATION
1.1 NATURALLY OCCURRING RADIOELEMENTS IN ROCK AND SOIL
1.2 SECONDARY GAMMA RADIATION FROM COSMIC RAYS
l. 3 ATMOSPHERIC AND TERRESTRIAL CONTAMINATION
(i) Gaseous Radioelements(ii) Radioactivity of Natural Particles
In Atmosphere and Precipitation
(iii) Radioactivity of Synthetic Particlesin the Atmosphere .- ASSOCIATED v/trtt Tic Derecrof
PAGE
rf*)
/.tJ, -f2 FACTORS AFFECTING SIGNAL STRENGTH
2.1 SOURCE CHARACTERISTICS
(i) Activity of Surface Materials Contributing to Signal
(ii) Individual Radioelement Concentrations
(iii) Thickness of Source and Absorption
(iv) Geochemical Halos
(v) Weathering of outcrops and Overburden
(vi) Effect of Overburden
(vii) Vegetation
(viii) Precipitation
(ix) Effective Radiating Area
2.2 AIR CHARACTERISTICS
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DETECTOR CHARACTERISTICS >
(i) Compton Scattering , 5(ii) Detector Crystal Volume . to
(Hi) Spectrometer Stability H
(iv) Sampling Rate /i
3 OPTIMIZATION OF SURVEY PARAMETERS H
4 DESCRIPTION OF AIRBORNE SYSTEM FLOWN OVER THESIS AREA IZ
5 DESCRIPTION OF GROUND INSTRUMENTS USED IN THESIS AREA /5"
PART B-COMPARISON OF AIRBORNE SURVEY RESULTS WITH GROUND FOLLOW-UP DATA
6 DESCRIPTION OF CLAW LAKE /7
6.1 LOCATION AND ACCESS rt
6.2 TOPOGRAPHY AND VEGETATION /7
6.3 REGIONAL GEOLOGY 17
l AIRBORNE DATA 39
9 DISCUSSION AND CONCLUSIONS
8 GROUND DATA J5
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1.
_PRODUCTION
In the summer of 1975 an airborne gamma-ray spectrometer
survey was conducted in northern Ontario under the joint Federal-
Provincial Uranium Reconnaissance Program by the Geological
Survey of Canada and the Ontario Division of Mines. After the data were released in 1976, 12 contiguous claims were staked by
Noranda Exploration Company, Limited near Claw Lake on an anomaly
which was thought to be a very good exploration target. A brief reconnaissance into the area proved inconclusive in determining
the source of the anomaly.A more detailed study was undertaken by the author from the
22nd to 29th of August, 1976, in an attempt to provide further
information and conclusions.This thesis consists of two main parts:
A - a detailed review of airborne gamma-ray spectrometer surveys,
B - a comparison of airborne and ground results in the Claw Lake
area.
PART A - AIRBORNE THEORY
INTRODUCTION
Airborne gamma-ray spectrometry provides a method of
estimating the abundance of potassium, uranium, and thorium in
surface materials beneath the aircraft.40 Potassium is measured directly from K which emits photons
at 1.46 MeV so'disequilibrium is not a problem. The radioactive
decay of uranium and thorium is more complex though and proceeds214 through many successive steps. Bi with photons of energy
1.76 MeV and 2 08T1 with photons of energy 2.62 MeV, intermediate
decay products within the uranium and thorium decay schemes, respectively, are used to measure indirectly their parent element
concentrations.214Bi and Tl were chosen because they are relatively
abundant, high in energy and are also most easily descriminated
from other gamma rays in the spectrum.
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O flivtM ^Vt friWty*V Figures l and 2, after Grasty and Darnley (26) ,j\gamma
rays over 0.1 MeV emitted by thorium and uranium in equilibrium
with their decay products. Measurements are only correct if the decay series is in equilibrium forming a closed system.
Radium and radon gas are intermediate decay products in the21 (j
uranium decay scheme. In an open environment B i may be
spatially separated from its parent uranium through migration
of intermediate decay products such as these. There is less
evidence to suggest that disequilibrium may be a problem in the Th decay series but measurements for both are commonly written
"eU" and "eTh" meaning equivalent uranium and thorium.
l SOURCES OF RADIATION
This section is devoted to four main sources of radiation which have been suggested by Gregory (28).
1.1 NATURALLY OCCURING RADIOELEMENTS IN ROCK f, SOIL
The only geologically significant radio-isotopes that have
gamma photons capable of penetrating through the air to the
altitude at which the airborne detectors are flown are certainA Q
members of the uranium, thorium decay series and K. These
elements may occur separately or together in various proportions,
depending on the geochemical nature of the source.
1.2 SECONDARY GAMMA RADIATION FROM COSMIC RAYS
When high energy cosmic particles pass through the atmosphere
they produce a radiation complex that includes gamma photons.
The exact nature of cosmic gamma flux is not completely under
stood but it is believed to contribute a relatively constant
low background flux which does not vary significantly below
altitudes of 50,000 feet. Some cosmic ray bursts are known to
occur which have produced significant, non-reproducable, positive anomalies of short duration/ (Gregory (28)).
Secondary radiation effects resulting from cosmic ray ir
radiation of rock are negligible as sources of gamma flux, Hess
and Roll (32) .
1.3 ATMOSPHERIC AND TERRESTRIAL CONTAMINATION
Three principal sources of contamination are as follows:
{i) Gaseous Radioelements
While gaseous radioelements existing in the atmosphere may
contribute to the general radiation background, they are con
sidered to be of little importance as parents of air turbulence
and precipitation. It is not known by the author if a full
evaluation of the gamma effect from uranium decay products ac
cumulated under temperature inversion conditions in the atmosphere
has been attempted. However, from measurements taken on seven
different days at the calibration pads at Uplands Air Force base,
near ottawa, Darnby and Grasty (26), found that uranium counts
showed a variation of up to 20%. They believe a significant
part of this was due to atmospheric radon content.
{i i) Radioactivity of Natural Particles in Atmosphere
and Precipitation
214 The variability of atmospheric Bi is due to changes in
atmospheric composition stemming from environmental factors
such as porosity and composition of ground, recent rainfall,
wind strength, pressure gradient, surface saturation or deep
continuous snow cover, etc., (Darnley, 11). Under fine summer214
weather conditions, he observed that the Bi content measured
at an altitude of 125m is normally at a maximum in the early
morning and commonly diminishes by 10-151 as the day progresses,' 214owing to atmosphering mixing. Variations in the Bi background
of the order of ID-20% have also been noted occassionally in the
early morning within neighbouring parts of a valley.
Charbonneau and Darnley (3) have observed an unusually high
uranium count of 5 times background which was apparently the
result of a heavy rainstorm. They attributed this to a high214
prqportion of Bi associated with dust particles being deposited
on the ground.
(iii) Radioactivity of Synthetic Particles in the Atmosphere
The radioactivity of synthetic particles (i.e. fallout) in
the atmosphere may cause important intensity variations. It is
f.
c
possible that such material could cause sharp, intense anomalies
or broad, irregular anomalies depending on the size of the con
taminated air mass.
1.4 RADIOELEMENTS ASSOCIATED WITH THE DETECTOR
Wrist-watches and aircraft instruments which contain radium
luminized dials must not be used.FACTORS ::r"V::;V"
^ FACOTRS AFFECTING SIGNAL STRENGTH
The interrelationships between factors affecting signal strength are complex. The parameters involved may be best
described under source, air, and detector characteristics.
2.1 SOURCE CHARACTERISTICS
(i) Activity of Surface Materials Contributing to Signal
Practically all soil and rock types tend to-exhibit with a surprising degree of uniformity a chacteristic intensity of
gamma radiation.
Kellog et al (31), Gregory (28), Russel (44) and others have
described the relative activities of some common materials.
(ii) Individual Radioelement Concentrations
The primary spectrum from an aggregate of radioelements in
the source is the summation of the separate spectra for each of the radioelements present.
Uranium series, thorium series, and potassium differ
greatly in their activities and signal variation is complexly
dependent on their ratio.
(iii) Thickness of Source and Absorption
Gamma-rays are attenuated in the surface material as a
result of self-absorption which is dependent on^density. The
relationship between depth, density, and effective gamma flux
received has been explored by Gregory and Horwood (30) and their
results are summarized in Table 1.
TABLE l ABSORPTION OF GAMMA-RAYS IN SOURCE AS A FUNCTION OF DENSITY
ROCK TYPE DENSITY gm/cm^
DEPTH REQUIRED FOR GAMMA RADIATION cm
TOTAL
granitedry overburden
2.71.5
15 - 2: 30 - 4!
(iv) Geochemical Halos
Although radioactivity measurements are only representative
of a relatively thin surface layer, one should not assume that more deeply buried ore bodies could not be detected. Airborne spectrometry, like many geochemical exploration techniques, relies on primary and secondary dispersion halos. Transportation
of material in solution and vapour form, precipitation of radioactive salts at the surface, movement due to hydrostatic gradient, and evaporation of fluids in rock may occur at or near buried ore to enrich the surface material.
(v) Weathering of Outcrop or Overburden
Geologically recent weathering and removal of uranium may
be quite common but does not necessarily pose a problem. Aslong as residual radium, intermediate in the decay scheme
214 between uranium and Bi, has not migrated beyond distances
of 50-100m removal of uranium is of little consequence. No evidence has been found for migration beyond these distances which are of the order of magnitude of spatial resolution of
airborne systems.
(vi) Effect of Overburden
The Canadian Shield is a prime target for airborne methods
because of its large area and relative inaccessibility. Sur face cover is dominated by overburden, swamp, or lakes with only a small percentage of bedrock exposed.
Overburden must be locally derived or residual in order that the results of the survey be meaningful. A detailed study by Darnley and Fleet (13) covering a variety of rock types rep resentative of the Canadian Shield revealed that the pattern
of radiation from shallow overburden is similar both in in tensity and distribution to that of exposed bedrock. It was concluded that to characterize a rock type it is not necessary to be dependent solely upon the radiation from occasional out
crops.
T{vii) Vegetation
Background variation between areas may be affected by the
presence of trees and brush which themselves contain a small
amount of radioelements (Cannon and Kleinhampl (1)).
(viii) Precipitation
Conditions of surface saturation or deep snow cover screen
radiation from the detector.
(ix) Effective Radiating Area
Since the airborne gamma ray spectrometer acts as a passive
sensor measuring gamma radiations from a surface of infinite
areal extent, the source may be represented as a continuous distribution of point source emitters of various intensities.
This distribution can be expressed as a function D (x,y) which
gives the intensity at any (x,y) co-ordinate position. Wh-n
this surface (ground) distribution of source intensities is viewed from the air, what the detector measures is modified by
the effects of distance R from the source and the absorption coef
ficient u of the air. The response of the detector can be ex
pressed as a point-detector function relating detector responseto distance. Them attenuation of intensity with distance is the, .. - function: e f
s
Source -
Thus, for an ideal source-detector geometry with a point
detector at an altitude h feet above an infinite plane, the
intensity measured at a certain point by the detector is the
product of the value of the point-detector function and the
value of the surface intensity distribution function at each
8.
c*Fan infinite number of points on the ground. The value re corded on the radiometric profile is the sum of all these
products.Thus the radiometric profile is the convolution of two
functions: the surface radioactive intensity distribution function, and a point detector function relating detector re sponse to distance. Mathematical descriptions have been given
by Pierson and Franklin (38), Duval et al (19) , and more re cently by Clark et al (6) as follows:
where R ^ x + y + h
e radiometric profile function~ ground distribution of radioactive
source intensities;i,k /**K ^ constants:k describes the constant factors affecting 'the count rate
of the particular system including detector efficiency:;j is the absorption coefficient
It is apparent that the size of an exposure with high
specific surface activity will affect the distribution function;
D (x,y) , by contributing to the source flux measured at the detector. Similarily topographic relief will affect the dis tribution function by increasing the surface area of the source
and may vary the solid angle subtended by the source at the detector. Flight lines should also be chosen approximately normal to the geological strike to provide maximum resolution
of geological features.
2 . 2 AIR CHARACTERISTICS
The amount of attenuation of the signal in the air is principally dependent upon the air density and the distance
between the source and detector. Since the signal strength is proportional to e - ^ y the effect of distance is apparent. The absorption coefficient, p , is a function of density. and con trols the relative attenuation of various photons.
The density of the air may vary with air pressure/ temperature, and humidity. The relative flux attenuations
is U, Th,and K. With increase in air distance, K and Th
fluxes increase in prominence relative to U flux.The principal advantage of flying at lower terrain clear
ance is in increasing spatial resolution. Disadvantages of flying at a low elevation are that it is more hazardous/ navigation is more difficult, as also is track recovery, and more line miles are necessary tq cover a given area. It is
important that terrain clearance be monitored and taken into account. A 50 foot change in terrain clearance may produce a 1C^ change in count rate from a large area source. For a small area source the change in count rate will be even more severe.
2.3 DETECTOR CHARACTERISTICS
(i) CoTipton Scattering
It is well known that high energy gamma-rays produce a certain fraction of scattered photons of lower energy which contribute to count rates in lower energy photopeaks. This effect is called Compton scattering. The scattered photons
may be produced inside the crystal detector itself or outside by scattering within the source material or in the air. In creasing the size of the crystal increases the fraction of photons which are totally absorbed in the crystal thereby also increasing the number of counts in the photopeak.
The contribution ratios, also referred to as stripping ratios are defined as:**"s counts in the "u"-channel per count in the "Th"-channelft - counts in the "K"-channel per count in the "Th"-channel
](** counts in the "K"-channel per count in the "U"-channelThe corrected count rates are given by the following
equations {after Darnley, (11)):
/o.
NTh
Nu
corr
corrNkcorr "
where NTh ,
BGO
N
N
Th
U
NK
NU'
- BCDi- BCD
- BCD
Th
U
y.
- N
- NThcor r
Thcorr " NNy e count
. backg rt
rates in
)und count
Ucorrthe Th, U, X channels
rate in a particularchannel indicated by a subscript
corr ** subscript referring to corrected countrates
The stripping ratios are dependent on the geometry of the
source as well as the window width employed and the size, num ber and spacing of the radiation detectors. The coefficients,
•i, /i, and if should be determined under natural survey con ditions. Since it is impossible to know the geometrical
shape of the source, a homogeneous source of effectively in
finite size is the most suitable model for calibration pur
poses. To this end, the Geological Survey of Canada has built five calibration pads 2.5 feet by 25 feet and 18 inches
thick, spiked with different amounts of uranium and thorium. The aircraft or helicopter mounted spectrometer may be taxied over the pads and calibrated. A detailed description of the procedure along with computer programs for determining tj-, f , and X are given by Darnley and Grasty, (25).
{i i) Detector Crystal Volume
The detector volume should be large enough to pick up
anomalous areas on the ground of the desired dimension. If
the detector volume is too small for its intended use either spatial or radiation intensity resolution will suffer. In .
theory it is not possible to have a detector volume which is
too large for a particular application. In practice, however,
there is an upper limit to volume arising from the fact that
although count rate increases, resolution decreases because of
self shielding effects. To make ratio measurements useful a
high count rate is required.
lJ J.
(iii) Spectrometer Stability
Since drift of "energy windows" causes large fluctuations
in count rate, spectrometer stability must be carefully control
led. To minimize instablility caused by drift in the high
voltage supply and temperature dependent variations in the
gain of the photomultiplier tubes, some spectrometers make use
of automatic gain adjustment using an isotope of known energy
as a monitor. The two isotopes most commonly employed areOAT l *^7
Am which is an alpha emitter and Cs, a gamma emitter.
Recently Co has been advocated to avoid some of the dis- .
advantages inherent in the other two.
It has become common practice to maintain the whole de
tector system at a constant temperature by means of a thermostatically controlled heating jacket.
(vi) Sampling Rate
The rate at which measurements are taken should not be confused with count rate previously discussed. Ideally, to
fully define the shape of an airborne radiometric profile,
the sampling rate should be made as high as possible. In pr^^tice this leads to very poor counting statistics which
introduce high frequency variations in the radiometric profile.
l OPTIMIZATION OF SURVEY PARAMETERS
Since the airborne radiometric profile given by equation
(1) is a space-varying function which can be considered to be
composed of different frequency (wavelength) components, the size of an anomalous zone can be related to its obporved wave
length, A , on the radiometric profile.
Since the contribution to the transform of the exponent
^in - equation (1) has been shown numerically to be negligible, Killean et al (33) have approximated the Fourier transform of
the point detector function by:
f ' 7 ' l
where is the wavelength of the spectral component of the anomaly, The function of equation (2) can be considered to be the fre
quency response of a smoothing function (i.e., the point de- tc 2tor function) which operates on the ground intensity dis-
1Z.
function to produce the radiometric profile. A plot
of the point detector transform versus frequency (or wavelength)
for any chosen altitude falls off as the wavelength decreases.
Such a plot is given by Killean et al (34), who have also
arbitrarily defined a cutoff value \ e , by a value of 1/e of the maximum amphitude component of the point detector trans
form function. This yields a practical lower limit of wavelength resolvable at altitude, h, and is given by:
X - k /Z l J]It should be recalled from section 2.3 (iv) , a practical
limit exists in the sampling rate because of high frequency variations in the radiometric profile. The sampling rate also
determines a minimum resoluable wavelength/ called the Nyquist wavelength, X* , given by:
X. . z vA-t [41where A t ~ length of sampling time in seconds i
v = aircraft speed in ft. /sec.A compromise yielding the best counting statistics for a
given flight altitude is given by equating X* and X* . This
yields an optimum sampling time of:
where h is the altitude associated with a chosen value of ^* . cTo resolve a particular wavelength of anomaly in the radio
metric profile, the maximum flight altitude is fixed at twice the critical wavelength desired. Alternate choices of sampling
time and velocity exist depending on the desired accuracy of
the counting statistics. A large detector volume will permit the use of higher speeds and lower sampling time. Counting
statistics for a particular airborne system can be determined
by. trial flights over areas of known radioelement concentrations.
The economics of detector and flying costs must be balanced with
the counting statistics, target size, and survey parameters.
i DESCRIPTION OF AIRBORNE SYSTEM FLOWN OVER THESIS AREA
The Geological Survey of Canada and Atomic Energy of
C
, Limited have produced the high sensitivity spectrometer
system which was flown over the study area of this thesis.
The G.S.C. was responsible for initiating the program, setting
performance targets, selecting and organizing field test areas
and trials, and undertaking complimentary geological, geophysical and geochemical investigations. A.E.C.L. was responsible for
design and construction of the components, operating the equip ment in the field, computer programming, and derivation of quantitative data from the airborne measurements.
The system eventually chosen so as to guarantee a more
than adequate count rate had twelve 9 inch diameter by 4 inch deep (22.86cm x 10.16cm) Na (I) Tl crystals.
Four 3 inch diameter phototubes were found experimentally
to be more efficient than one 12 inch diameter phototube.
The individual crystal and photomultiplier combinations have
been found to possess a resolution of 12t. The -crystals and
photomultipliers are encapsulated in a 0.019 inch thick
stainless-steel container. Each crystal assembly is packaged
in a metal canister lined with approximately l inch of
polyurethane foam which is molded to accommodate the crystal
and form a container for it. It was found feasible to wire the
corresponding electrodes of the four tubes in parallel without any significant loss of resolution. This greatly simplified
gain matching adjustment of the 48 photomultiplier tubes. Each crystal is maintained at a constant temperature of 100OF by
means of an electrical heating element attached to the wall of
the canister. The individual canisters are grouped in sets of
six inside an aluminium box which is filled with polystyrene
foam insulating material. There are, therefore, two containers
each approximately 4.5 x 4 x 2.5 feet in size.
TABLE 2 ENERGY WINDOWS AND ATTENUATION COEFFICIENTS FOR SKYVAN SYSTEM
(AFTER DARNLEY, (II))
ELEMENT ISOTOPE ANALYSED USED
K 4 0K
0 2 14B1Th ' 2 08T1
f- RAYENERGY (MeV)
1.46
1.72
2.62
ENERGY WINDOW (MeV)
1.36-1.56
1.66-1.82
2.42-2.82
0.4 -2.82
AIR ATTENUATION COEFFICIENT., (ftr'^i' x 10 *#)
2.3
1.7
1.7
2.0
J4.
tTable 2 shows the energy windows and isotopes used by the
\. S.C. system. The air attenuation coefficients as determined
by Darnley (11) are also included. Three single-channel
analysers accept energy from each of these spectral windows
, while a fourth single-channel analyser accepts a band ofradiation which virtually represents the total or integral
count rate from the whole energy spectrum. Associated with
each analyser is a scalar which totals the counts and sub
tracts a pre-determined background in each case for a time
which can be pre-selected. Provision is included for sampling
the output from the integral count analyser more often than the other three by a factor whjjh can be pre-selected on the
timer.
An incremental digital tape recorder is used to sequentially
record the following information at the end of each sampling
interval:
- accumulated total count less background- accumulated K count less background
- accumulated U count less background- accumulated Th count less background- sampling time intervals
- average height in feet over preceding sampling interval
- elapsed distance along flight lines- deviation normal to flight line
- date- flight line information
- operator code numberAn anomaly presentation of the data is provided in flight
by means of a strip chart recorder. The associated navigational
aids include a Bendix ALA-51 radioaltimeter and a Bendix Doppler
navigational system for providing elapsed distance along pre determined flight lines, together with deviations normal to the
line. The navigational system is usually supplemented by a
conventional track recovery camera or TV-video tape recording
system. The digitized information enables a print out of all
A? required parameters corrected as necessary for altitude and
Compton scatter and to produce contoured geochemical maps.
Grasty and Darnley ( 25) have determined the stripping ratios from seven completely independent Skyvan calibrations
as follows:
** - 0.348 0 .015 (4.3^)
fi ~ 0 .331 ± 0.044 ± (13.31) y = 0.560 ± 0.102 ± ( IS.2%)
It should be noted that "S the most critical coefficient,
is the most accurately determined. The total weight of the
spectrometer is 1600 Ibs. A Skyvan was found most suitable
as the survey platform because of its STOL performance, low
control speed, and high rate of climb.
5^ DESCRIPTION OF GROUND INSTRUMENTS USED IN THESIS AREA
Two different instruments were used in the ground follow-
up operations in the thesis area.
The Exploranium model GRS-101 portable gamma ray scintil
lometer is a total count instrument which measures all gamma
radiation above 0.05 MeV. The instrument includes a threshold
setting which automatically triggers an audio tone when the
meter exceeds a preset value. A 1.25" diameter x l" thick
(3.18 x 2.54cm) sodium iodide crystal with a total volume of
1.23 cubic inches (20.1cm ) is employed in the instrument.
The other instrument used was the McPhar model TV-1
three threshold scintillometer. This instrument uses the same
size detector crystal as the Exploranium scintillometer. In
addition to the meter, a speaker provides a variable pitch
output with changing radiation levels. The three threshold
positions are as follows:
Tl at 0.2 MeV - measures the total count across the entiregamma energy spectrum for maximum sensitivity
T2 at 1.6 Mi-V - measures characteristic uranium and thoriumradiations
T3 at 2.5 MeV - measures diagnostic thorium radiation's only
^^ In the total count threshold, Tl, a fast or slow time
cmistant (i.e. sampling interval) may be selected at l or
10 seconds. For T2 and T3 the time constant is set at 10
seconds.
The counts due to U and Th are determined as follows:
counts due to Th ^ C 3r1l = C 3 - C3g counts due to U ^ C^u ^ C Z (Ufrll) - 3 .5 CJr*
~ (CZ - C28 ) - 3.5 (C, - C^)
where the subscripts are defined as: B = background; 1/2,3 channel in which count observed.U, Th, = source of count.
17.
RT B - COMPARISON OF AIRBORNE SURVEY RESULTS WITH GROUND
FOLLOW-UP DATA
i DESCRIPTION OF THE CLAW LAKE AREA
6.1 LOCATION AND ACCESS
The 12 claims are located in the Thunder Bay district,
58km northwest of the town of Savant Lake which is situated
on highway #599. The property was found most readily ac
cessible by taking a float plane to Claw Lake where a base camp was established. The claim group was about 2.5km east
of Claw Lake at latitude 50O 42'N and longitude 90O 10'W,
NTS 52J-9.
6.2 TOPOGRAPHY AND VEGETATION
Most of the claim group is covered in glacial debris which
varies from unsorted till to material primarily composed of
boulders with little or no fine material interstially.
The boulder-rich debris may be found as long sinuous
hills or boulder fields. Many of the glacial features trend
in a southwesterly direction.
Spruce trees comprise essentially all of the forested
areas. Alder swamps containing scattered spruce trees are
common in most of the low areas.
6.3 REGIONAL GEOLOGY
Three published geological maps (37, 42, 45), which in
clude the thesis area are of limited value. No work had been
done in the vicinity of Claw Lake owing to the large scale
reconnaissance nature of these mapping projects.
The study area lies within the English River Subprovince
of the Superior Province. Archean splutonic masses of variable
dimensions and areal extent which are composed of a wide variety
of granitic rock types dominate the subjrovince. Six miles
to the west of the claim group lies the northern tip of the
Savant Lake greenstone belt which is mainly comprised of fine
INTEGRAL
MAP 2 TO
TAL C
OU
NT
CO
NTO
UR
S
500-
250
500-
'J? v"o
t.
Ou500-
POTASSIU
M(D
CO
NTO
UR
S10
IQUIYALENT URANIUM MAP 5"
eqiv. UR
AN
IUM
ppm
CO
NTO
UR
S
MAPS
EQIVALENT THORIUM-MAP 7
eqiv. THO
RIU
M ppm
. CO
NTO
UR
S
MAP 8
EQUIVALENT URANIUM l EQUIVALENT THORIUM RATIO MAP 9
eU/eT
h CO
NT
OU
RS
MAP ,o
EQUIVALENT URANIUM X POTASSIUM RATIO MAP H
EQUIVALENT THOmUM-X-.LO.tASJMUM— ——— ~IS
ELEVATION MAP 15
- AEROMAGNETIC MAP MAP 16
GROUND SCINTILLOMETER SURVEY
"EXPLORANIUM" TOTAL COUNTS PER SECOND
MAP 17
GROUND SONTILLOMETER SURVEY MAP 18
"McPHAR" T l READINGS — COUNTS PER MINUTE
GROUND SCINTILLOMETER SURyEY
T2 READINGS COUNTS PER MINUTE
"MCPHAR" T3 READINGS - COUNTS PER MINUTE
OUTCROP DISTRIBUTION
AND
ASSAY RESULTS
massive to foliated, chloritic, mafic, metavolcanics
a few narrow units of felsic metavolcanics and meta-
sediments.
;7 AIRBORNE DATA
The airborne gamma ray spectrometry data (maps 1-15)
are compiled from the preliminary geophysical series maps
produced by the Ontario Division of Mines and Geological Sur
vey of Canada (39), (40). North-south flight lines at 5km
spacings were flown at a mean terrain clearance of 400 feet
at 190kmXhour.
The data for three of the flight lines are presented as
enlarged composites of the ODM-GSC profiles (40), for integral
count, potassium equivalent uranium and equivalent thorium
concentrations, the eU/eTh, eU/K, and eTh/K ratios, and survey
altitude. These profiles have been superimposed.on a base map
to show the relationship to water covered areas. The data
have also been presented as enlargements of computer contoured
maps (39) for each of the seven radiometric parameters. Uranium,
thorium, and potassium counts were measured over 2.5 second
intervals; integral counts over 0.5 second intervals. The
data have been corrected for background, height variation and
spectral scattering. Computer programmes used to produce
the contour maps and profiles are described by Grasty, (22).
This programme tends to distort the contours in the direction
perpendicular to flight lines. The profiles provide a more
accurate means for locating anomalies. Factors relating
airborne measurements to element concentrations were determined
by relating the corrected airborne count rates over test strips
in the Ottawa area to known ground radioelement concentrations,
(Gr'asty and Charbonneau, (25)).
Map 16 is an enlargement of part of an aeromagnetic survey
conducted for the Ontario Division of Mines (39).
i GROUND FOLLOW-UP DATA
8.1 SCINTILLOMETER SURVEY
Maps 17-20 show the results of a ground scintillometer sur-
within the study area. Eight lines were surveyed using a
compass and 30m chain for a total distance of 3270m stations
every 30m, four readings were taken including total count with
the Exploranium model GRS-101 scintillometer and total count,
, characteristic uranium and thorium, and diagnostic thoriumreadings with the McPhar model TV-1 scintillometer. Vegetation,,
degree of ground saturation, and nature of surficial material
were also noted during the survey.
8.2 GEOLOGICAL MAPPING
The property was mapped by pace and compass technique with
the assistance of airphotos. The chained and flagged scintil lometer grid greatly aided the precise fixing of outcrop position,
The geology of the area is shown on map 22 (back cover). An attempt has been made to show the major glacial and topographic
features. Map 21 shows the results of some assays taken from outcrops in the area. The outcrop distribution can be seen
more easily on this map than the geology map.
C
41.
DISCUSSION AND CONCLUSIONS:~
Examination of the airborne spectrometry data would suggest
that this area provides excellent prospects as an exploration
target. Flight line 5 passed directly over the claim-group
( 00 the airborne and ground result* should correlats well.
The eU counts display a broad anomalous region 8 miles in
diameter with count rates up to seven times background. The eO
anomaly is centred in the northern half of the claim-group as i*
a good eU/eTh ratio and excellent eU/t ratio. The eTh/Xratio i*
average for the region which.is a favourable indication that
preferential enrichment of uranium rather than thorium may b* '
responsible for the anomaly. While the eTh and total count data
suggest the centre of the anomalous son* may lie about on* syll*
north of the claim-group, count rates are still anomalous over the
area of the ground study.
Upon close examination of the total count , K, and eTh profiles
and contour maps, a striking similarity is apparent. This would
strongly suggest a very geochemically sympathetic relationship
exists between Th and K. Owing iito the similarity of the X and
eTh profiles, the eU/eTh and eU/K profiles should also be very
similar. This is easily verified by even a cursory examination.
The eU/eTh and eU/X data, although similar to the K and eTh data,
ahow a stronger .resemblance to the el) data. From an exploration
viewpoint this is desirable and may indicate preferential enrichment
of uranium within the area.
H*ving dicussed some of the interesting aspects of the airborne
data,a comparison should be drawn with the ground results. The
geology map, (back cover), attempts to show the topographic and
glacial features in addition to the outcrop geology. ft variety.,
of granitic rocks were found in the area. These include biotite-
and (or) hornblende- quarts-feldspar gneiss, hybrid granite gneiss,
pegmatite, and a few, small, low count rate, migmatised cones
V ' bearing mafic rich lenses up to 10 feet in length which are most
likely xenoliths. Typical ground scintillometer values in areas of
outcrop were of the order of 90-140 cps. with some local high counts
^ up to 240 cps. which is not unusual for granitic rocks, four samples
which were assayed were taken from widely spaced outcrops which had
above average count rates. The 00 , ,ThO , and X assay result* vex*38 *
i" low and are shown on nap 21. Mo uraninite stain or other
precipitate was noticed on the outcrops. The outcrops did not appear
extremely weathered so their is no direct evidence suggesting that
disequilibrium in the decay scheme could bs a problem* Tn* ground
scintillometer results (maps 17, 18, 19, 20), show tt* low
background count rate that is characteristic of the area, The
lower readings at the southern end of lines 2, 3, and 4 are due to
the swampy nature of the area.
Airphoto examination reveal* an area of sandy glacial outwash
to the north of the Claw Lake anomaly. It seems likely that the
boulder fields and boulder hills noticed within the area are a
lag deposit resulting from the removal of finer detritial material
by glacial meltwater. Readings taken of the boulders throughout the
study area gave values similar to those of the outcrop. The
similarity in lithology between the boulders and outcrop suggests
that the overburden is residual or locally derived.o
The glacial trend in the area is N20 B whereas the structural
trend, as determined from regional lineaments, is about N35 B.
Attempted correlation between radiometric, structural, and glacial
trends proved inconclusive in determining whether the anomalous
sons is structurally or glacially controlled.
Variations in aircraft height can be eliminated as a potential
source for the observed anomaly. Prom map 15 it can bs seen that
terrain clearance was maintained extremely well along flight line 5
within the area of concern. The highest topographic feature in
the area is a drumlinoid structure at the northwest end of Claw
Lake. The feature was examined and found to have a very low
background count rate.
Equation 5 yields 0.58- seconds as the sampling time for
optimum counting statistics. Since integral counts were takem at
0.5**eoond intervals and owing to the large detector volume of the
spectrometer system, count rates were high enough to avoid problems.
It should be noted that the ground measurement* should be
nore reliable than the airborne observation*. Problem* such as
unknown source and air attenuation are eliminated In ground work,
While the background total count rate for the airborne measurement*
was approximately 5 tines that of the ground measurements, the
integrating time of the ground measurements were greater by a
factor of 20.
Change* in the temperature of the photomultiplier tubes or
instability in the spectrometer system resulting in Spectral
window drifting would not satisfactorily explain the anomaly
since it can b* followed between lines 4, 5, and 4.
The only plausible explanations for the anomaly seem to be
that either a temporary radiation source, such as was dicussed
in section* 1,2 and 1.3, cau**d the anomaly or that some source
north of the area studied, possibly combined with the effect*
of the boulders within the claim-group, produced the anomaly.
Although the exact nature of the effects of cosmic ray bursts
are not completely understood it can be ruled out a* the source
of the anomaly unless it* effect we* local l iced in the area
covering all three flight line* over the period they were flown.
It i* extremely unlikely that temperature inversion, causing
concentration of gaseou* radioelement*, could produce *uch sharp
effect* over an area a* small a* the anomaly'214
Bi in the atmosphere can produce largo end variable change*
in the background radiation, affecting both the absolute count
rate and the value of the apparent height coefficient. Increased
Bi in the atmosphere would contribute photon* only to the
U-channel and through Compton scattering to the K-chennel. Since
the airborne indicated Th was also anomalous in the area,
(map* 7 and 8), Bi i* an unlikely explanation "of the anomaly.
Synthetic particle* in the atmosphere could cause intense
anomalies such as the one discussed but verification is not
possible.
Temporary sources of radiation do not satisfactorily explain
the anomaly in the authors opinion.
44.
The possibility of the anomaly being the result of a lag
1 deposit in conjunction with a source north of the ci aim-group
poses some interesting problems which cannot be resolved without
further ground work. Since the claia-group was covered in some
( detail during the mapping and ground scintillometer surveys, it
is very unlikely that any significant exposure within its
boundaries was missed. The contribution of the boulder* is no
doubt more significant than that of the outcrop but it is debatable
that it could cause the observed seven-fold increase above
background observed in the eU-channel. The possibility exists
that the source of the anomaly lies north of the property. Most
of the profiles suggest the anomaly is composed of severs! peaks
of various amplitudes. These peaks are more prominent on some of
the profiles north of the property than within it. The computer
contoured maps may be somewhat misleading because of their smoothing
function. There is some support for s more northerly source
provided by the regional geology and the aeromagnetic anomaly
pattern. The anomalous zone lies within a 3-mile wide, relatively
undisturbed, ENE-WSW trending aeromagnetic belt. To the north
and south of the anomaly the area is magnetically disturbed.
Both the relatively undisturbed band and its surrounding magnetically
disrupted areas have similar average magnetic readings which would
suggest deformation rather than variations in lithology to be
responsible for the bands.t (These magnetic liniaments are likely
shear cones or faults. The northern magnetically disturbed belt
iShOf particular ir,terest. It is alligned with lineaments produced
by the pinching out of the Savant Lake Greenstone Belt, (42).
If this is a fault sons, enrichment along it micht explain many of
the peaks north of the claim-group with the lag deposit accounting
for many of the peaks in the profile near the claim-group. .
Airphoto examination does not reveal t fault but if one exists it
may well be covered by the sandy outwash in that are*.
t
45.
In conclusion, correlation between ground and airborne results
is at best confusing in the Claw Lake area and many questions
remain unanswered. Since the purpose of airborne surveys is to
provide a more efficient means of arriving at "ground truth"
it appears that the airborne system may have fallen short of this
objective at least in the area of the claim-group. It must be
emphasized that gamma-ray spectrometer profiles are not a
panacea and.it is extremely important to interpret them whenever* '*'' ' '
possible with all forms of complimentary evidence.
As technological developments progress and detectors capable
of better energy resolution become available, the advantages of
recording the complete gamma radiation spectrum on magnetic tape
may be realised. This would eliminate many of the problems
discussed.
C.
REFERENCES
Cannon, H. L. and Kleinhampl, F. J.1955: Botanical Methods of prospecting for uranium; Paper
509, Int. conf. on peaceful uses of atomic energy,Geneva.
2. Charbonneau, B. W.1973: Ground Investigation of the Mont Laurier airborne
radioactivity survey; in Report of Activities, Part A, Geol. Survey Canada, Paper 73-1, pt. A, p. 67-78.
3. Charbonneau, B. W. , and Darnley, A. G.1970: Radioactive precipitation and its significance to
high sensitivity gamma-ray spectrometer surveys; in Report of Activities, Nov. 1969 to Mar. 1970; Geol. Survey Canada, Paper 70-1, pt. B, pp. 32-36.
4. Charbonneau, B. W. , and Darnley, A. G.1970: A test strip for calibration of airborne gamma-ray
spectrometers; in Report of Activities, Geol. Survey Canada, Paper 70-1, pt. B, pp. 27-32.
5. Charbonneau, B. W., Richardson, K. A. , and Grasty, R. L.1973: Airborne gamma-ray spectrometry as an aid to geo
logical Tapping, Township No. 155 Elliot Lake area, Ontario? in Report of Activities, pt. B, Geol.
Canada, Paper 73-1, pt. B, pp. 39-47.6. Clark, R. B., ^ -al Jr., J. S. and Adams, J. A. S.
1972: Computer simulation of airborne gamma-ray spectro-t meter; J. Geophysics Res., 77(17): 3021-3031.
7. Darnley, A. G.1968: Helicopter tests with a gamma-ray spectrometer;
Can. Min. J., v.89, no. 4, p. 104-106.8. Darnley, A. G.
1970: Airborne gamma-ray spectrometry; Can. Min. Me tall, ; Trans., v.73, p. 20-29.
9. Darnley, A. G.1972: Airborne gamma spectrometry survey in areas of Elliot
^ Lake, Ontario and Fort Smith, Northwest Territories;in Report of Activities, Part A, Geol. Survey Canada,
:. Paper 71-1, pt. A, p. 48-49.10. Darnley, A. G.
1973: The use of total Radioactivity measurements forreconnaissance airborne surveys; Geol. Survey Canadh,
? Paper 73-1A.11. Darnley, A. G.
1973: Airborne gamma-ray survey techniques present and future V. in Uranuim Exploration Methods. IAEA Vienna, p. 67-105.
12. Darnley A. G., Brislow, Q. and Donhoffer, D. K.1969: Airborne gamma-ray spectrometer experiments over
the Canadian Shield, in Nuclear Techniques and Minerali Resources, International Atomic Energy Agency, Vienna, l p. 16 3-186.
(
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24..
25.
Darnley, A. G. and Fleet, M.1968: Evaulation of airborne gamma-ray spectrometry in
Bancroft and Elliot Lake areas, Ontario; in Report of Activities, part B, Geol. Survey Canada, Paper 68-1, pt. B.
Darnley, A. G. and Grasty, R. L.1971: Mapping from the air by gamma-ray spectrometry, Can.
Inst. Min. Met., Spec, v 11, p. 3-12.
Darnley, A. G. , G rasty, R. L. , and Charbonneau, B. W.1969: Airborne gamma-ray spectrometry nnd ground support
operations; in Report of Activities, Part B, Geol.Survey Canada, Paper 69-1, pt. B, p. 10.
Darnley, A. G., Grasty, R. L. and Charbonneau, B. W. 1970: Highlights of G. S. C. airborne gamma spectrometry in
1969; Can. Min. J. April, p. 98-101.
Darnley, A. G., Grasty, R. L. and Richardson, K. A.1972: Regional variations in radioelement cor.tent within
the Canadian Shield; 24th Int. Geol. Con-jr. Montreal,Sect. 9, Exploration Geophys. , p. 14.
Darnley, A. G., Richardson, K. A. , and Grasty, R. L.1972: Experimental airborne gamma-ray spectrometry surveys;
in Report of Activities, Part A, Geol. Survey Canada,Paper 72-1, pt. A, p. 46-49.
Duval, J. S., Cook, B. and Adams, J. A. S.1971: Circle of Investigation of an airborne gamma-ray
spectrometer. J. Geophys. Res., 76(35): 8466-8470.
Exploranium1975: Portable gamma-ray scintillometer model GRS-101
data sheet.
Geological Survey of Canada1954: Prospecting for uranium in Canada.
Grasty, R. L.1972: Airborne gamma spectrometry data processing manual,
GSC Open File No. 109.
Grasty, R. L.1973: Gamma-ray scattering corrections for the airborne
measurements of uranium; in Report of Activities, Part A, Geol. Survey Canada, Paper 73-1, pt. A, p. 82.
Grasty, 1975:
R. L.Uranium stripping determination au natural for air borne gamma-ray spectrometry; Geol. Survey Canada, Paper 75-1, Part A, p. 87.
Grasty, R. L. and Charbonneau, B. W.19/4: Gamma-ray spectrometer calibration facilities; in
Report of Activities, Part B, Geol. Survey Canada,Paper 74-1, pt. B, p. 69-71.
48.
Grasty, R.L., Darnley, A.G.1971: The calibration of gamma-ray spectrometers for
ground and airborne use; Geol. Survey Canada,Paper 71-17.
27. Grasty, R.L., Holman, P.B.1974: Optimum detector sizes lor airborne gamma-ray sur
veys; Geol. Survey Canada, Paper 74-1, Part B, p.72-74.28. Gregory, A.F.
1960: Geological Interpretation of Aeroradiometric Data Ceol. Survey Canada, Bull 66.
29. Gregory, A.F., Fournier, A.L.196-: The effect of temperature on response of scintil
lation counters; Geophysics, v.25, No.6, p.1288-1290.
30. Gregory, A.F., Horwood, J.L.1961: A labratory study of the gamma-ray spectra at the
surface of rocks; Minos Br., Dept. Mines Tech. Surv., Ottawa Research Rep. R110.
31. Kellog Bartlett Kessler etc.
32. Hess, V.F., and Roll, J.D.1948: New Experiements Concerning the Surplus Gamma
Radiation of Rocks; Phys Review, vol.73, pp.592-595.
33. Killean, P.G. and Carmichael, C.M.1970: Gamma-ray spectrometer calibration for field analysis
of thorium, uranium, and potassium; Can. J. Earth Sci., v.7, no.4, p.1093-1098.
34. Killean, P.G., Hunter, J.A. and Carson, J.M.1971: Some effects of altitude and sampling rate in airborne
gamma-ray spectrometric surveying; Geoexploration, v.9, no.4, p.231-234.
35. Killean, P.G., Hunter, J.A., and Carson, J.M,1975: Optimizing some parameters for airborne gamma-ray
spectrometric surveying; Geoexploration, v.13, p.1-12.
36. McPharModel TV-1 three threshold scintillometer instrument manual.
37. Moore, E.S.1927: Savant Lake Gold Area, map no.37j, District of Thunder
Bay, Ontario, Division of Mines.
38. Ontario Division of Mines1960: Neverfreeze Lake Area, Thunder Bay District,
aeromagnetic map 920G.
39. ODM-GSC1976: Airborne gamma-ray spectrometric survey, Sioux
Lookout sheet contour maps, Districts of Kenora and Thunder Bay; Ontario Division Mines, Prelim, Maps P.1112-1118, leophys. Ser., scale 1:250,000. Survey and compilation for OD?, and GSC, 1975.
49,
ODM-GSC1976: Airbotne gamma-ray spectrometry survey profiles of
integral, K, U, Th, (U/Th), (U/K), (Th/K), height, Sioux Lookout Sheets, Districts oi ienora and Thunder Bay; ODM Prelim Maps P.1119-1146, geophys. ser, scale 1:250,000. Survey and compilation for ODM and GSC, 1975. :
41. Peirson, D.H. and Franklin, E. ' \1951: Aerial prospecting for radiometric minerals. Br. !
J. Appl. Phys., 2:281-291. ]
42. Pye, E.G., Davies, J.C. and Pryslak A.P.1966: Sioux Lookout - Armstrong Sheet, G.C.S., Ontario
Division of Mines, M.2169.
43. Richardson, K.A.1973: Airborne radioactivity measurements over the
Canadian Shield, Geol. Survey Canada, Paper 73-1, Part A, p.94.
44. Russel, W.L.1944: The Total Gamma-Ray Activity of Rocks as indicated
by Geiger Counter determinations; Geophysics Vol.9, pp.180-216.
45. Sage, R.P., Breaks, F.W., Stott, G., and Mcwilliams, G. andBowen, R.P.1974: Operation Ignace-Armstrong-Pashkokogan-Caribou Lakes
sheet, District of Thunder Bay, Ontario Div. Mines, Prelim. Map P.962. Geol. Ser., scale l" to 2 miles, neology, 1973.
Ministry ofNaturalResources
Ontario
b
CLAW LAKE 900
78 02 07
Kr. Harry L. Bellining Recorder
Ministry of Natural Resources Box 669 Court House Sioux Lookout, Ontario POV 2TO
Your file:
Our tile: 2.2447MINISTRY OF NATURAL RESOURCES
RECEIVEDFEB101978
RESIDENT GEOLOGIST'S OFFICE SIOUX LOOKOUT
Dear Sir:
Re: Mining Claims Pa. 376378 et al, Claw Lake Area File 2.2447^,^..^^^,.^,,^.^.,^^^—^,^-.
The Airborne Geophysical (Radiometric) and Geological assess ment work credits as shown on the attached statement have been approved as of the above date.
Please inform the recorded holder cf these mining claims and so indicate on your records.
Yours very truly,
McGinn, Director sfnds Administration Branch
Whitney Block, Room 1617 Queen's Park Toronto, Ontario M7A 1X1 Phone: 416-965-6918
DN/mw
cc: Noranda Exploration Company, Ltd. Thunder Bay, Ontario Attn; Mr. R. S. Woolverton
cc: Noranda Exploration Company, Ltd. Toronto, Ontario
cc: Resident GeologistSioux Lookout, Ontario
r *
Ministry ofNajuraiResources
Ontario
LandsAdministrationBranch
Projects Unit Technical Assessment
Work CreditsFile 2.2447
Recorded HolderNoranda Exploration Company Limited
Township or AreaClaw Lake
Type of survey and number of Assessment days credit per claim Mining Claims
GeophysicalElectromagnetic
Magnetometer.
Radiometric — 10
Induced polarization
Section 86 (18)^.
Geological ——— 10
Geochemical.
.days
.days
.days
.days
.days
.days
.days
Man days D
Special provision O
Airborne bil
Ground C3
Hotte* of Intent to b* is*u*d:
CD Credits have been reduced because of partial Coverage of claims.
O Credits have been reduced because of corrections to work dates and figures of applicant.
O No credits have been allowed for the following mining claims as they were not sufficiently covered by the survey:
Pa. 376378 to 81 inclusive
376390 to 93 "
436403 -04
436415 - 16
Jfc - .'if "V The Mining Recorder may reduce the a')ovo credits if necessary in order that the total number of approved assessment days recorded on
' tl'MCh claim doe* not exceed the maximum allowed as follows: Geophysical — 80; Geological —40; Geochemical — 40;
Ontario
Ministry of Natural Resources
GEOPHYSICAL - GEOLOGICAL - GEOCHEMICAL TECHNICAL DATA STATEMENT
File.
TO BE ATTACHED AS AN APPENDIX TO TECHNICAL REPORTFACTS SHOWN HERE NEED NOT BE REPEATED IN REPORT
TECHNICAL REPORT MUST CONTAIN INTERPRETATION, CONCLUSIONS ETC.
Type of Survey(s) GEOLOGICAL SURVEY———————— Township or Area CLAW LAKE AREA M. 2134————— Claim Holder(s) NORaNDA EXPLORATION COMPANY, LIMITED
BOX 45. COMCRCE COURT VI., TOBCNTO
Survey Company NQRflNDA EXPLORATION COMPANY, LIMITED
Author of Report BARRIE F. JOSE______________Address of Author BOX 2656. THUNDER BAY, CNTARIO
Covering Dates of Survey AUGUST 21-SEPIEMBER 2, 1976( [incoming to office)
Total Miles of Line Cut ___________________ ! -
SPECIAL PROVISIONS CREDITS REQUESTED
ENTER 40 days (includes line cutting) for first survey.
ENTER 20 days for each additional survey using same grid.
Geophysical
—Electromagnetic.—Magnetometer^—Radiometric——
DAYS per claim
-Other.Geological 2Q On each of
12 claims Geochemical______——
AIRBORNE CREDITS (Special proviwon crediu do nol ipply to airborne lurveyi)
Magnetometer. .Electromagnetic.(enter dayi per claim)
DATE- JULY 5' 1977 SIGNATURE:,
. Radiometric
Res. Geol.. Q.. a lifirr.,innc ^3' l f Q*
Previous Surveys File No. Type Date Claim Holder
JUL i l
MINING CLAIMS TRAVERSED List numerically
PA 376378(prefix)
PA 376379(number)
PA 376380
PA 376381
PA 376390
PA 376391
PA 376392
MINISTRY OF NATURAL RESOUi
R EC SJ-V ED!l1sioux LOOKOUT
PA 376393
PA 436403
PA 436404
PA 436415
PA 436416 '
TOTAL CLA1MSJ2.
*.N
feU
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