An analysis of detailed airborne geophysical survey from the by alicejenny

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									                                              An analysis of a detailed airborne
                                                 geophysical survey from the
                                                    Poole River Prospect,
                                                      EasternVictoria
                                               for Reedy Lagoon Corporation.




Hugh Rutter
Exploration Director, Reedy Lagoon Corporation Ltd
Consulting Geophysicist, Geophysical Exploration Consultants Pty. Ltd.

DISCLAIMERS

Confidentiality
This document and its contents are confidential and may not be disclosed or published in any manner (except in its entirety to a government
department as part of the statutory reporting requirements and as may otherwise be required by law) unless Geophysical Exploration Consultants
Pty Ltd [‘GEC·] has given its prior consent to the form and context of the disclosure or publication.


Disclaimer
GEC has prepared this report based upon information believed to be accurate at the time of completion, but which is not guaranteed. GEC makes
no representation or warranty as to the accuracy, reliability or completeness of the information contained in this report and will not accept
liability, (including for negligence) to any person for any errors or omissions or for losses or damages claimed as a result, directly or indirectly, of
items discussed, opinions rendered or recommendations made in this report, except for statutory liability which may not be excluded.
                                     Contents


1. Introduction

2. Summary of previous exploration

3. Poole River Geophysical Survey

      3.1. Introduction

      3.2. Magnetic data

      3.3. Radiometric data

             3.3.1. Total count channel
             3.3.2. Potassium channel
             3.3.3. Uranium channel
             3.3.4. Thorium channel
             3.3.5. Radiometric ratios

      3.4. Magnetic profiles

      3.5 Magnetic modelling and interpretation

4. Conclusion and recommendations.
An analysis of a detailed airborne geophysical survey from the Poole River Prospect,                          3
Eastern Victoria for Reedy Lagoon Corporation, April 2003




                                                  Figures


1. Magnetic intensity contours
2. Magnetic intensity and flight line plan
3. Mean terrain clearance

4. Radio-activity: total count channel
5. Radio-activity: potassium channel
6. Radio-activity: uranium channel
7. Radio-activity: thorium channel
8. Radio-activity: ratio (Th.Th)/K
9. Radio-activity: (K.K)/(Th.U)

10. Magnetic intensity and proposed ground grid

11a. Magnetic profiles 58000N, 57500N, 57000N, 56750N
11b. Magnetic profiles 56500N, 56000N, 55500N, 55000N
11c. Magnetic profiles 54500N, 54000N, 53500N

12a. Line 57000N, airborne magnetic profile,, model results (k = 444.10-5SI units) and
drilling
12b. Line 57000N, airborne magnetic profile,, model results (k =1290.10-5SI units) and
drilling

13. Drill hole WPPG1 (Aloren), magnetic susceptibility
14. Drill hole WPPG1a (Aloren), magnetic susceptibility

15. Line 57000N, magnetic model results and potential geological equivalent
16. Line 57500N, airborne magnetic profile, topography and model result
17. Line 58000N, airborne magnetic profile, topography and model result
18. Line 56750N, airborne magnetic profile, topography and model result
19. Line 56500N, airborne magnetic profile, topography and model result
20. Line 56000N, airborne magnetic profile, topography and model result
21. Line 55500N, airborne magnetic profile, topography and model result
22. Line 55000N, airborne magnetic profile, topography and model result
23. Line 54500N, airborne magnetic profile, topography and model result
24. Line 54000N, airborne magnetic profile, topography and model result
25. Line 53500N, airborne magnetic profile, topography and model result
26. Line 30000E, airborne magnetic profile, topography and model result

27. Magnetic intensity contours, earlier Aloren surveys




Hugh Rutter, Geophysical Exploration Consultants Pty. Ltd. Suite 2, 337a Lennox Street, Richmond, Victoria 3121
Tel: 61 3 8420 6230                   Fax: 61 3 8420 6299              email: HughRutter@compuserve.com
An analysis of a detailed airborne geophysical survey from the Poole River Prospect,                          4
Eastern Victoria for Reedy Lagoon Corporation, April 2003


1. Introduction

Poole River is a tributary of the Thomson River in the upper area of the water catchment.
It is 120 km east of Melbourne and 10 km south west of the small township of Woods
Point. Access to the prospect is by road from the east, north or south, then by well
maintained bush tracks. The topography is severe with changes in elevation of up to 300
m in places.

The Poole River prospect is a 90 nT magnetic anomaly. It is 5000 metres in strike length,
situated in a flexure zone of the Enochs Point and Eildon thrusts. Local geology can be
obtained from the 1: 250,000 scale Warburton geological map. It is part of the area
selected by the Geological Survey of Victoria for regional and mineral deposit studies
during the period October 2002 - December 2006.

The prospect is on the western side and central to, the Walhalla-Jamieson Goldfield,
from which 98 tonnes of gold was obtained with an average grade of 30 gm/t. The
Morning Star Mine at Woods Point produced 19.6 tonnes of gold. Further south, along
the thrust zone, the Thomson River Copper Mine produced 2,500 tonnes grading 3.75%
Cu, 0.34% Ni, 6.2 gm/t PGE‰s.

The geological and tectonic setting, coupled with the rich associated mineralisation
make the Poole River magnetic anomaly a prime target for exploration.

2. Summary of previous exploration

In the late 1980's two airborne magnetic surveys were flown over part of the Walhalla
Synclinorium with the objective of locating diorite dykes of the type related to gold
mineralisation at Woods Point, A1 Mine Settlement, Loch Fyne, etc.

Magnetic susceptibility measurements had been taken from dyke rock at The Comet
Mine, All Nations Mine and The Morning Star Mine; the results are as follows.

The Comet Mine

                  Sample       Magnetic susceptibility. 10-5 SI units         Comments
                    1                         40                          oxidised dyke rock
                      2                          15                       oxidised dyke rock
                      3                          55                       oxidised dyke rock
                      4                          35                       oxidised dyke rock
                  Average                        36




Hugh Rutter, Geophysical Exploration Consultants Pty. Ltd. Suite 2, 337a Lennox Street, Richmond, Victoria 3121
Tel: 61 3 8420 6230                   Fax: 61 3 8420 6299               email: HughRutter@compuserve.com
An analysis of a detailed airborne geophysical survey from the Poole River Prospect,                          5
Eastern Victoria for Reedy Lagoon Corporation, April 2003


The Morning Star Mine

                   Sample      Magnetic susceptibility. 10-5 SI units         Comments
                      1                          550                        fresh dyke rock
                      2                          600                        fresh dyke rock
                      3                          40                         oxidised dyke
                                                                                rock
                      4                          350                        fresh dyke rock
                   Average                 fresh rock: 500


The All Nations Mine

                   Sample      Magnetic susceptibility. 10-5 SI units         Comments
                      1                         1500                        fresh dyke rock
                      2                          30                         oxidised dyke
                                                                                rock
                      3                          40                         oxidised dyke
                                                                                rock
                      4                         1000                        fresh dyke rock
                      5                          100                        fresh dyke rock
                      6                          70                         oxidised dyke
                                                                                rock
                      7                          150                        fresh dyke rock
                      8                          10                         oxidised dyke
                                                                                rock
                   Average                 fresh rock: 688

                   Average             oxidised dyke rock: 38




                   Sample      Magnetic susceptibility. 10-5 SI units          Comments
                      1                           5                       Ordovician siltstone
                      2                          10                       Ordovician siltstone
                      3                           5                       Ordovician siltstone
                      4                           15                      Ordovician siltstone
                      5                           5                       Ordovician siltstone
                   Average                        8




Hugh Rutter, Geophysical Exploration Consultants Pty. Ltd. Suite 2, 337a Lennox Street, Richmond, Victoria 3121
Tel: 61 3 8420 6230                   Fax: 61 3 8420 6299               email: HughRutter@compuserve.com
An analysis of a detailed airborne geophysical survey from the Poole River Prospect,                          6
Eastern Victoria for Reedy Lagoon Corporation, April 2003


The sample is not large, but indicates a magnetic susceptibility for fresh dyke rock
ranging from 100.10-5 SI units to 1500.10-5 SI units with an average of 600.10-5 SI units.
This is a factor of 10 times the background values of the Ordovician siltstone.
The airborne magnetic surveys did not convincingly identify the dykes associated with
the known mines. This was partly due to the metallic debris remaining at these sites
(head-frames, rails, kibbles, etc. Also, many prospective anomalies were found to be
caused by basalt remnants and pockets of alluvial magnetite.
However, at the junction of the two surveys to the east of Woods Point a much more
substantial magnetic anomaly was identified which is now the basis of the Poole River
Prospect. The original magnetic signature is shown in figure 27.
Drilling conducted by a previous tenement holder identified limited intersections of
altered dyke rock but measurements of the magnetic susceptibility on the total core did
not record values high enough to account for the airborne magnetic anomaly, (figures 13
and 14). It follows, therefore, that the source of the Poole River magnetic anomaly is still
to be discovered.

3. The Poole River airborne geophysical survey

3.1. Introduction

The 1994 Poole River airborne geophysical survey was flown specifically to acquire high
quality data for the magnetic anomaly located by the earlier surveys. The line spacing is
100 metres and the magnetic sensor was planned to be 100 m above ground. The
airborne data shown in this report is part of a slightly larger survey and has been
selected to define the Poole magnetic anomaly.

3.2. Magnetic data

The magnetic contour map with a contour interval of 2nT is shown in figure 1. The
anomaly has a maximum anomaly of 70 nanoTeslas. The total strike length is close to 5
km in a north-west to south-east direction. The smaller 2 - 20 nT anomalies are thought
to be caused by alluvial magnetite in some of the water courses, basalt remnants on the
ridge tops and possible small outcrops of dioritic dyke rock.
The flight line plan is shown superimposed on a magnetic image in figure 2. In general
the line spacing of 100 metres has been maintained reasonably well. The mean terrain
clearance is shown in figure 3. The planned flight height of 100 metres is highlighted. It
is estimated that 85% of the survey is within 10% of this height, ie a mean terrain
clearance of less than 120 metres.




Hugh Rutter, Geophysical Exploration Consultants Pty. Ltd. Suite 2, 337a Lennox Street, Richmond, Victoria 3121
Tel: 61 3 8420 6230                   Fax: 61 3 8420 6299              email: HughRutter@compuserve.com
An analysis of a detailed airborne geophysical survey from the Poole River Prospect,                          7
Eastern Victoria for Reedy Lagoon Corporation, April 2003


3.3. Radiometric data

The radiometric data were not the prime objective of the survey but were recorded and
processed at very little additional cost

3.3.1. Total count channel

The total count channel is shown in figure 4 and bears a close relationship with the
mean terrain clearance. This indicates that in most instances an increase in radio-
activity is caused by a lesser distance between the sensor and the ground. Background is
estimated to be 1000 cps and except in the north-east corner where there are some
processing errors, nowhere achieves a value of twice background.

3.3.2 Potassium channel

Shown in figure 5, the estimated background is 70 cps. Slightly higher values occur in
the south-east and may indicate a greater abundance of potassium felspars in the
country rock.

3.3.3. Uranium channel

In figure 6 the uranium channel results are contoured with an interval of 5 cps. The
estimated background is 16 cps with some small areas achieving twice background
values, eg 432250E 5834000N. The cause of this small increase has not been looked for
on the ground.

3.3.4. Thorium channel

Anomalous thorium values sometimes indicate areas of alteration, particularly argillic
alteration. The thorium channel contours are shown in figure 7. Background is estimated
to be 45 cps. Some areas are marginally above background but they to not relate very
closely to the potential position of the cause of the magnetic anomaly. However, these
areas appear to strike in the same direction but slightly to the west.

3.3.5. Radiometric ratios

The purpose of calculating ratios of the radiometric channels is to minimise the
influence of topography and variable ground conditions. The ratio (Th.Th)/K , figure 8,
is designed to highlight increase in thorium relative to potassium and therefore highlight
areas of potential alteration. Two areas of weakly anomalous values are centered at
431500E 5833500N and 432750E 5832250N, both of which lie to the west of the
magnetic zone.
The ratio (K.K)/(Th.U), figure 9, is designed to show areas of potassic alteration. There
are many “spot” anomalies which are probably the result of the low overall data values
and, therefore, do not indicate an increase that can be related to the surface geology.



Hugh Rutter, Geophysical Exploration Consultants Pty. Ltd. Suite 2, 337a Lennox Street, Richmond, Victoria 3121
Tel: 61 3 8420 6230                   Fax: 61 3 8420 6299              email: HughRutter@compuserve.com
An analysis of a detailed airborne geophysical survey from the Poole River Prospect,                          8
Eastern Victoria for Reedy Lagoon Corporation, April 2003


3.4 Magnetic profiles

An artificial grid has been superimposed on to the airborne magnetic contour plan so
that a series of representative magnetic profiles could be extracted. It extends from
53000N to 58000N with a baseline of 30000E. The location of the grid is shown in
figure 10. As yet, the grid has not been located on the ground. Magnetic profiles extracted
for this grid are shown in figures 11a, 11b and 11c. It is unlikely that any of these profiles
show only the response from the magnetic body in the thrust zone. It is apparent from
the data away from the main anomaly that there are many low amplitude anomalies.
Ground work has identified these as being caused by detrital magnetite on the surface,
remnants of basalt, topographic effects and, in some case, dioritic dyke rock. Therefore
the minor variations seen on the magnetic profiles, eg 30600E on line 57500N, 29700E
on line 57000N and 29950E on line 56750N, are probably ‘residual· anomalies
relative to the main magnetic anomaly.

Topography was derived from a digitised version of the 1: 25,000 topographic map. This
was related to the mean terrain clearance of the magnetic sensor to provide flight height
profiles. This information was incorporated in the magnetic modelling results which
follow.

3.5 Magnetic modelling and interpretation

Line 57,000N is the most critical line in the analysis of the magnetic data as it includes
the Aloren drill-hole WPPG1/1a. The spatial location is shown in figure 10, and the
location along the magnetic profile 57,000N in figures 12a, 12b and 15. The drill site was
positioned using the results of two earlier magnetic surveys; the relevant parts of these
surveys are shown contoured in figure 27.

The model result shown in figure 12a allowed all parameters to be varied during the
modelling process. But the modelled curve is not a good fit, particularly on the western
flank of the anomaly. Comparing this field profile to that from the adjacent lines,
57,500N and 56,750N it appears that there is an additional magnetic response on the
western side. If the model is weighted to the peak amplitude and the values on the
eastern side the result is a much narrower source. Also, the magnetic susceptibility for
the model result in figure 12a is 444. 10-5 S.I. units. This can be varied up to 1290. 10-5
S.I. units without degrading the model data fit.

The magnetic susceptibility measured on the core from WPPG1 averages less than 50. 10-
5 S.I. units with some sections rising up to 60 units and the occasional spike up 150

units, (figure 13). None of these values reach those required by the modelling process.

The magnetic susceptibility measurements from WPPG1a, which is a deeper hole, are
higher with an average of 60. 10-5 S.I units between 150 metres and 390 metres with
sections up to 150 units and spikes to 300 units. Below 390 metres the magnetic
susceptibility falls to an average of 20. 10-5 S.I. units, (figure 14).



Hugh Rutter, Geophysical Exploration Consultants Pty. Ltd. Suite 2, 337a Lennox Street, Richmond, Victoria 3121
Tel: 61 3 8420 6230                   Fax: 61 3 8420 6299              email: HughRutter@compuserve.com
An analysis of a detailed airborne geophysical survey from the Poole River Prospect,                          9
Eastern Victoria for Reedy Lagoon Corporation, April 2003


The average model result is shown in figure 15. The model used is a tabular body with a
limited strike length; it is assumed to be homogeneous. The lower section in figure 15
shows one possible geological interpretation which will satisfy both the magnetic
modelling and the drill intersections. It is also noted that small outcrops of weathered
dyke material have been mapped on the surface in the vicinity of the anomaly. The dip of
the model is consistently to the west which means that the earlier drilling was directed
down dip.

Figures 16 to 25 summarise the modelling results for the remaining lines between
53,500N and 58,000N. Potential drill sites, based on the magnetic data, are shown for
line 56,750N (figure 18), 56,000N (figure 20) and 55,500N (figure 21). In all cases the
tabular model probably represents a complex suite of rocks with variable magnetic
susceptibility and mineralogy.

A longitudinal section has been constructed (figure 26) which illustrates the relationship
between topography, magnetic response and interpreted depth to the top of the magnetic
body
North of 55200N the depth to the top of the magnetic body varies between 50 m and 250
m before plunging to more than 300m in the extreme north. The top of the body is
relatively flat
with the variation in depth being the result, predominantly, of the topographic relief. It
should be remembered that the model used is that of a flat topped tabular body and it is
probable that geological reality is much more complex. The model result on each line is
the best fit to the airborne magnetic data but there is always a range of acceptable
results. The given depths may vary by up to 15-20% associated with changes in the
magnetic susceptibility.


4. Conclusion and recommendations.

The earlier drill hole was sited on magnetic data which was not acquired using modern
measuring, navigating or recording systems. Also, the anomaly straddles two surveys
flown on separate occasions. The relevant part of the amalgamated surveys is shown in
figure 27. The survey flown by RLC was focussed on the magnetic anomaly with
stringent flight path and flight height tolerances with the result that the magnetic data is
of much higher quality and the ability to model the data is much improved.

The drill hole WPPG1a intersected weathered dyke rocks of similar composition to those
hosting gold mineralisation further to the east, e.g. Morning Star Mine. The full
geological log is contained in the Aloren drill hole completion report. It includes the
recommendation that the geological environment and weak mineralisation intersected
requires further investigation. This new magnetic data provides an improved basis for
interpretation with the ability to site further drill holes which will optimise the chances
of success.




Hugh Rutter, Geophysical Exploration Consultants Pty. Ltd. Suite 2, 337a Lennox Street, Richmond, Victoria 3121
Tel: 61 3 8420 6230                   Fax: 61 3 8420 6299              email: HughRutter@compuserve.com
An analysis of a detailed airborne geophysical survey from the Poole River Prospect,                         10
Eastern Victoria for Reedy Lagoon Corporation, April 2003


The anomaly is located in a flexure of the Enochs Point Thrust Zone which forms the
western boundary of the major Walhalla-Jamieson Goldfield. It is along structure from
the Thomson River Copper Mine from which additional platinum group elements were
mined.

The Poole River anomaly is considered to be highly prospective for gold mineralisation
and copper/platinum/palladium mineralisation. Further drilling is recommended.




Hugh Rutter
Exploration Director, Reedy Lagoon Corporation Ltd
Consulting Geophysicist, Geophysical Exploration Consultants Pty. Ltd.




Hugh Rutter, Geophysical Exploration Consultants Pty. Ltd. Suite 2, 337a Lennox Street, Richmond, Victoria 3121
Tel: 61 3 8420 6230                   Fax: 61 3 8420 6299              email: HughRutter@compuserve.com

								
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