rpt on mag em & geol sur€¦ · t-53815 and t-53816. the surveys the procedure and pertinent...
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31M04SW0I86 63.1724 STRATHY010
REPORT GS VERTICAL MAGNETIC INTENSITY. ELECTROMAGNETIC AND GEOLOGICAL SURVETS OF THE KEEVIL CONSULTANTS LIMITED DORIS LAKE CLAIMS. STRATH! TOWNSHIP DISTRICT OF NIPISSING.______ONTARIO
INTRODUCTION
The initial tailings basin for the Sherman Mine at Timagami
will inundate portions of several claim groups adjacent to the eastern
half of Vermilion Lake. One of these groups is not controlled by
Cliffs of Canada, and the recorded holders do not want flooding to
occur until the mineral potential of the claims is ascertained.
Accordingly, during parts of March, April and May, 1965, three sep
arate magnetic, electromagnetic and geological surveys were carried
out to assess the possibility of mineral occurrences.
PROPERTY
The property consists of a group of six unpatented mining
claims in the Timiskaming Mining Division, numbered as follows:
T-52187 (1)T-52190 - 91 inclusive ( 2)T-53814 - 16 inclusive (3)
These claims are recorded in the name of T. G. Robinson,
of North Bay, who holds them in trust for Keevil Consultants Limited,
a member of Keevil Mining Group Limited.
LOCATION AND ACCESS
The claims are located in Strathy Township adjacent to the
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northeast end of Vermilion Lake, and north of it. Th* group lies
about 3Jj miles WNW of the village of Timagand, which is 65 miles
north of North Bay.
Easiest access is by float equipped aircraft from Timagand,
landing on Vermilion Lake. The trip takes less than five minutes.
A canoe route leads north from Lake Timagand via Turtle and Tetapaga
Lakes. A bush road westward from Goward, three miles north of
Timagand, passes close to the northwest corner of the group.
PREVIOUS WORK
Considerable trenching and test pitting was done in the
past. One diamond drill hole was found on claim T-52191. It is
located 300 feet south of baseline "B" and 20 feet east of cross
line 8400W (see plan SM-86c). The hole had apparently been drilled
northward. Some core remained at the site and sections containing
pyrite and pyrrhotite (apparently barren) were noted. During the
summer of 1964, self-potential and geological surveys of claims
T-52187, T-52190 and T-52191 were carried out by Geophysical
Engineering and Surveys Limited for Keevil Consultants Limited.
This work was submitted for assessment credit on September 16, 1964
and subsequently approved. The credit consisted of 43 assessment
days geophysical and 40 assessment days geological per claim, for
a total of 166 assessment days.
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TOPOGRAPHY
Doris Lake is about 55 feet above the level of Vermilion
Lake. Hills rise immediately west and south of Doris Lake to heights
of 115 and 150 feet respectively above Vermilion Lake. The highest
hill is on claim T-52191.
In general, the high ground contains numerous outcrops.
Overburden is shallow, but deepens where swampy ground occurs on
the west side of Doris Lake.
LINE CUTTING AND CHAINING
The line cutting and chaining on claims T-53814 - 16 inclus
ive was contracted to Simpson and Taylor, Ontario Land Surveyors, of
North Bay. A total of 7.25 miles of line, including baselines, were
cut with the cross lines at 200 foot intervals.
The two baselines already established on claims T-5218?
and T-52191 were extended westerly. The "A*1 or notfcbern baseline
was extended approximately 1,200 feet to cross claim T-53814, while
the WB" or southern line was lengthened 2,800 feet to cross claims
T-53815 and T-53816.
THE SURVEYS
The procedure and pertinent data of the three surveys are
described under separate headings. However, for clarity and conven
ience, the discussion and summary of all results are compiled under
-4-
a common heading.
1) Magnetic Survey - The field work was carried out on March 8-10,
17-20 inclusive, 1965. The instrument used was Jalander No. 5768,
a fluxgate magnetometer measuring the vertical component of the
earth's magnetic field. The sensitivity is 10 gammas per scale
division. A total of 10.5 miles of line were traversed and 688
stations were occupied. Readings were normally taken at 100 foot
intervals but the distance was decreased to 50 feet where anomalous
conditions were encountered. The results of the survey are plotted
on map No. SM-S6A. The values are given in gammas. Assessment data
for the survey will be found in the Appendix.
2) Electromagnetic Survey - The field work was carried out on
March 31 and April 1-6 inclusive, 1965. Again all the claims were
covered by the survey and 10.5 miles of line were traversed with a
total of 748 readings recorded. In gffect, continuous readings were
made possible by observing the instrument scale while moving along
the picket lines. This is an innovation, since the survey was ac
complished using a very portable, light-weight instrument, the re
cently developed Ronka E.M.15. This instrument is very satisfactory
for light overburden. It has a maximum depth penetration of 30 feet,
sufficient for even the heavier overburden marsh area at Doris Lake.
The transmitter has an operating frequency of 16,000 cycles
per second. Both transmitter and receiver coils are tilted at 35
-5-
from the vertical. A slightly different measuring system must be
used since neither dip angle nor in-phase, out-of-phase readings
are entirely applicable. The secondary signals from the series-
tuned receiving coil are amplified and fed to a syncronous detec
tor. The detector output, in fractions of milliamps, is read on
a centre-zero meter calibrated - 10 divisions. The sensitivity
is such that a secondary field of about 30 parts per million of
the primary field at the receiving coil, if parallel with the
receiving coil axis and in-phase with the primary field, will
give one small division deflection on the output indicator. De
flections indicate the magnitude of magnetic intensity of the
distorted primary field.
Signal components in parallel to the coll axis, opposite
in-phase to the primary field (1800 phase shift) are indicated
towards the red scale of the meter (-) to indicate a conductive
object. A magnetic non-conductive object is indicated on the blue
scale C+) in similar circumstances. The survey results are plotted
on map No. SM-86B. The information is presented as profiles along
the picket lines. The positive peaks are interpreted as represent
ing a zone of magnetic permeability; negative peaks indicate con
ductive zones. The profiles were corrected for slight temperature
effects. The readings are given in parts per million or fractions
of milliamperes. Assessment data for the survey will be found in
-6-
the Appendix.
3) Geological Survey - The following is a report on the geologic
mapping on the portion of the property not previously mapped by
Keevil Consultants Limited. The area is included in claims No.
T-53814, T-53815 and T-53816. The field work was carried out on
May 20-26, 1965.
PREVIOUS MAPPING
The area was included in the geological mapping by
W. W. Moorhouse, reported in O.D.M. Annual Report Vol. 51* part
6 (1942). As previously mentioned, three claims of the group,
T-52187, T-52190 and T-52191, had been mapped in detail during
1964.
GENERAL GEOLOGY
TABLE OF FORMATIONS
- Precambrian
Keewatin: - Rhyolite, acid agglomerates,carbonate and sericite schists.
- Andesite, tuff.- Basalt, tuff.
- - - - - intrusive contact - - - - -
Keweenawan:- Olivine diabase dikes.
- Quaternary
Pleistocene: Boulder-gravel overburden with a thin Recent layer of sand, gravel and peat.
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GEOLOGY
The Keewatin volcanics in the area are chiefly acidic
excepting in the northwest corners of claims T-53814 and T-53816
where andesites are present.
In general the acidic volcanics are made up of rhyolitic
flows and carbonate and sericite schists. This member varies from
massive lava type to pyroclastic and is not uniform in composition.
The degree of dynamic metamorphism greatly affects the lithology.
The rhyolite where massive exhibits a rusty weathered
surface but is quite resistant to weathering. Where it has been
sheared, however, the rhyolite has been deeply weathered. On the
accompanying map (SM-86c) the massive and lightly sheared rhyolites
are shown separately, but the highly sheared and/or altered rhyolites
are shewn as part of the schistose volcanics. The rhyolite is any
where from grey to greenish in colour and sometimes tends to be
slightly porphyritic with quartz being the phenocrysts.
Carbonate and sericite schists form the larger part of
the volcanic complex. They are principally highly altered rhyolite.
In places the schist contains blocks of massive relatively unaltered
rhyolite and these occurrences have been mapped as rhyolite breccia.
In places the altered flows are interbedded with agglomerate. The
schist is generally deeply weathered and very rusty, and varies in
colour from a very light brown to a dark grey.
-8-
The basis volcanics, andesite and basalt, are massive,
fine-grained and in places tuffaceous.
The Keweenawan olivine diabase occurs as two roughly
parallel dikes which strike approximately NSO0^ and dip very
steeply towards the south. Their contacts are irregular and have
the characteristic chilled zone. The diabase away from the con
tact is coarser-grained, lighter in colour and more magnetic than
the chilled zone.
Near the diabase contact the volcanics are usually darker
in colour due to a "baked" contact.
STRUCTURE
The only structural feature noted during the field mapping,
other than some jointing in the diabase, is the shearing. It strikes
just south of west, dipping steeply to the south.
MINERALIZATION
Sulfide mineralization occurs sporadically throughout the
volcanics in the form of dissemination of pyrite. This was the only
type of sulfide noted. Mineralization is somewhat more concentrated
at or near the diabase contacts. The best occurrence noted is 200
feet north of baseline "B" on line 0+00 where the sulfides accounted
for less than 1^ of the host volcanics.
9
RESUETS OF THE SURVEY
CORRELATION AND DISCUSSION OF THE GEOPHYSICS AND GEOLOGY
The magnetic survey indicated two parallel anomalous
magnetic lows trending about west by northwest across the property
and approximately 900 feet apart. The southern anomaly crosses
claims T-53815 and T-53816, while the northern anomaly crosses
claims T-52191 and T-53814. The electromagnetic survey indicated
the same two parallel anomalies and showed them to be zones of
greater permeability. It was suspected that these anomalies are
caused by the diabase dikes as shown on Moorhouse 1 s map No, 51e,
and the geological survey showed this assumption to be true.
The weak magnetic anomaly in the southeast corner of
claim T-52191 is probably due to the narrow iron formation mention
ed by Moorhouse in his report.
There are a few indications of minor conductors within
the anomalous zones where small negative depressions occur in the
electromagnetic profiles. The most interesting occur on lines
16+OOW, 0400 and 2+OOW, baseline "B" at the south arm of Doris Lake,
and indicate a conductive zone possibly up to 500 feet long. The
geology suggests that this is caused by water-filled fractures with
in the diabase dike, caused by the presence of the lake.
Other scattered conductor indications are observed on
line 10400W, claim T-52191; on line 6+OOW, claims T-53814 and T-53815;
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en line 1OKXM, claim T-53814; on line 24"KX)W, claim T-53816.
Since the indications follow the strikes of the diabase dikes,
they are probably caused by structural irregularities in those
dikes rather than sulfide concentrations.
The scarcity of outcrop in the most western part of
claim T-53816 frustrated attempts to discover the reason for the
split in the geophysical anomaly, but it is probably due to a
branching of the diabase dike.
CONCLUSION
From the extensive trenching done in previous years it
would appear that the area has been well prospected for mineral
occurrences. The main geophysical anomalies represent the diabase
dikes. No metalliferous mineralization, other than the scattered
pyrites, was encountered during the mapping. These observations
indicate that there are no zones large enough to be of economic
value.
Respectfully submitted,
Port Arthur, Ontario August 5, 1965
LEGEND a SYMBOLS T. 5381
KEEWATIN ACIDIC SCHISTS AND AGGLOMERATE a A GGLOMERATE b R HYOLITE BRECCIA h A LTERED RHYOLITE 5 CARBONATE AND SERICITE SCHIST
MAINLY MASSIVE, GREY TO GREENISH RHYOLITE
ANDESITE t T UFF
BASALT t T UFF
KEWEENAWAN OLIVINE DIABASE
T. 52403T. 52186
T. 52190
STRIKE AND DIP OF SCHISTOSITY
DORISSTRIKE AND DIP OF OBSERVED CONTACT
SULFIDE MINERALIZATION (PRINCIPALLY PYRITE)
52191\ \
ASSUMED GEOLOGIC BOUNDARY
W.D. 267ASSUMED GEOLOGIC BOUNDARY FROM GEOPHYSICS
T. 53816
CLIFFS OF CANADA LIMITEDPORT ARTHUR. ONTARIO
KEEVIL GROUPVERMILIONT. RT. 4621 CLAIMS
GEOLOGYDATA FROM MAY 1965 FIELD
WORK BY E.GROOTENBOER. DATE MAY 31, 1965
DRAWING NO. SM - 86 CSCALE : l = 200
31M04SWOie6 63.1724 STRATHY 200
T. 52403NOTES 1. (O INSTRUMENT USED. JALANDER NO. 5 768
T. 52186(2) READINGS SHOWN ARE THE CONVERTED
INSTRUMENT VALUES, CORRECTED FOR
DIURNAL VARIATIONS, IN GAMMAS. T. 53811(3) DATA FROM MARCH 1965 FIELD WORK.
T. 52190
T. 52\I87
DORIS
W.D 267
T. 5 \38I6 \.."
CLIFFS OF CANADA LIMITEDPORT ARTHUR, ONTARIO
KEEVIL GROUPT. R.T. 4621 VERMILION
CLAIMS
DATE : APRIL 14, 1965MAGNETIC SURVEYSCALE: i" s 200'CONT. INT. 1OOO GAMMAS
63. I724 STRATHY
NOTES; to INSTRUMENT USED: RONKA E.M.IS.
(2) DATA FROM APRIL 1965 FIELD WORK.
(3) THE PROFILES HAVE BEEN CORRECTED FOR SLIGHT TEMPERATURE VARIATIONS
AND ARE PLOTTED FROM AN ESTIMATED, COMMON GRAPHIC BASE, I.E. THE
LINE OF TRAVERSE IS GRAPHIC ZERO. THE CORRECTED READINGS SHOWN ARE
THEREFORE INSTRUMENT SCALE DIVISIONS OF POSITIVE OR NEGATIVE CHANGE,
A POSITIVE CHANGE (PROFILE PEAK) INDICATING GREATER PERMEABILITY AND
VICE VERSA GREATER CONDUCTIVITY.
INSTRUMENT SCALE DIVISIONS REPRESENT FRACTIONS OF MlLLIAtdPS.
14) VERT. SCALE PROFILES IS l" - 20 INSTRUMENT SCALE DIVISIONS.
T. 52403T. 5 Z l 8 6
5 3 811
t! - Ha
•'T. 52190T. 5 a\l 8 7
T.\ 53814\ \ i.f \
W.D. 267
T. 5 \3 8 l 6 T. 5 381
REVISIONS
DATE i BYCLIFFS OF CANADA LIMITEDPORT ARTHUR, ONTARIO
KEEVIL GROUPT. RT. 4621 VERMILION
CLAIMSDATE ftPRlL 15, 1965ELECTROMAGNETIC SURVEYDRAWING NO. SM-86 BSCALE: l = 200
31M045W0106 63.1724 STRATHY 220