BUREAU OF MINERAL. ,RESOURCE·S,· GEOLOGY AND …IP, Single-point resistance, SP and gamma logs, DDH1. IP, SP and gamma logs, DDH5. IP, SP and gamma iogs, DDH6. IP, Single-point resistance,

DEPARTMENT OF MINERALS AND ENERGY

BUREAU OF MINERAL. ,RESOURCE·S,· GEOLOGY AND GEOPHYSICS

I

Record 1974/67

OOWN-HOLE INDUCED POLARIZATION AND ELECTRIC APPLIED POTENTIAL TESTS

006543

AT BASIN CREEK NO. 1 PROSPECT, MEL 200, TUMUT, N.S.W~, 1973

by

R.D·. Ogi1vy

The information contained in this report has been obtained by the Department of Minerals and Energy as part of the policy of the Australian Government to assist· in the exploration and development of mineral resources. It may not be published in any form or used in a company prospectus or statement without the permission in writing of the Director, Bureau of Mineral Resources, Geology and Geophysics.

I I I I I I I I I I I I I I I I I I I I

Record 1974/67

DOWN-HOLE INDUCED POLARIZATION AND ELECTRIC APPLIED POTENTIAL TESTS

AT BAS IN CREEK NO. 1 PROSPECT, MEL 200 ~ TUMUT, N.S.W., 1973

by

R.D. Ogi1vy

I

I I I I I I I I I I I I I. I I I I I I I

1.

2.

3. 4.

5.

6.

7.

SUMMARY

INTRODUCTION

GEOLOGY

. CONTENTS

PREVIOUS GEOPHYSICAL INVESTIGATIONS

GEOPHYSICAL TECHNIQUES

4.1 IP Logging Method 4.2 Applied Potential Method

RESULTS

5.1 IP Logging 5.2 Applied Potential

CONCLUSIONS

REFERENCES

1

1

1

2

2 2

4

4 7

11

12


Plate 1.

Plate 2.

Plate 3.

Plate 4.

Plate 5. Plate 6. Plate 7.

Plate B.

Plate 9.

Plate 10.

Plate 11.

ILLUSTRATIONS

Locality map.

Surface plan of Basin Creek No. 1 Prospect, showing geology, grids and drillhole positions. IP, Single-point resistance, SP and gamma logs, DDH1.

IP, SP and gamma logs, DDH5.

IP, SP and gamma iogs, DDH6.

IP, Single-point resistance, SP and gamma logs, DDHB. Surface potentials with current source at drilling dept;.h190 ft. - 205 ft. in DDH1. Down-hole potentials with current source at drilling. depth 190 ft. - 205 ft. in DDH1. .

Surface potentials with current source at drilling depth 245 ft. - 257 ft. in DDHB.

Down-hole potentials with current source at drilling depth 245 ft. - 257 ft. in DDHS. Surface potentials with current sour~e at drilling depth 437 ft. - 440ft. in DDHS.

Plate 12. Down-hole potentials with current source at drilling depth 437 ft. - 440 ft. in DDHS.

Plate 13. Theoretical surface potentials.

I I I I I I I I I· I I I I I I I I I I I

SUMMARY

Between November 1972 and March 1973, the'Bureau of Mineral Resources,carried out several geoppysical test surveys in A.O.G. Minerals Basin Creek No. 1 prospect, near Tumut in N.S.W. Down-hole induced polarization (IP) , electrical, gamma-logging, and ap~lied potential techniques were employed in selected dr~llholes. The work was primarily experimental, aimed at tracing the extent of massive chalcopyrite mineralization intersected by early drilling.

The down-hole IP logging was carried out in four drillholes, but owing to adverse geophysical conditions and instrumental problems, met with only limited success in detecting conductive and mineraliz~d zones.

The applied potential technique .involving measurements in three dimensions provided valuable information on the extent and structure of the mineralized zones investigated. Several prominent extensions to known mineralized zones were indicated and two drillholes have been, recommended to test these findings.

The rugged terrain and the experimental nature of the applied potential survey did not permit more than a qualitative interpretation of results. Despite this, quite definite conclusions were obtained and the method's further development is recommended to assess the possibilities of more quantitative data evaluations.


1. INTRODUCTION

In co-operation with A.O.G. Minerals Pty Ltd, the Bureau of Mineral Resources carried out geophysical tests over the Basin Creek No.1 prospect, within MEL200, near Tumut in New South Wales (Pl. 1)."

Down-hole induced polarization (IP), eiectrical, and "gamma-logging techniques were e"mployed in selected drillholes. These and additional drillholes were subsequently used for a three-dimensional applied potential survey of the prospect to outline possible extensions to known mineralization and guide further explor~tory drilling.

The work was carried out at suitable stages in conjun~tion with A.O.G.'s drilling program. "In all, survey operations totalled 5 weeks in a period extending from 14 November 1972 to 31 March 1973.

2. GEOLOGY

The geology of the Basin Creek" area, based on mapping by Nethery and Bailey, is presented in Plate 2. The rocks belong to the Tumut Pond Group. Chloritic phyllite, tuffaceous agglomerate, and medium to coarse-grained tuff are predominant and form part of a vertically dipping metasedimentary sequence. The basic volcanics and volcanic breccias, although conformable, are "considered to be intrusive and possibly associated with the northern extensions of the Lobb's Hole-Talbingo ultrabasic belt.

Drilling shows both massive and " disseminated sulphid"e mineralization to be closely associated with the intrusive volcanics and fine-grained chlo~itic phyllite. The mineralization appears to be of volcanogenic or1g1n, with chalcopyrite the most abundant sulphide and only minor sphalerite, pyrite, and galena.

3." PREVIOUS GEOPHYSICAL INVESTIGATIONS

Previous geophysical work in the area includes a magnetic survey (Johnson, 1972) and an IP"survey (Tyne, 1971). The magnetic survey proved useful: in delineating structures, but owing to the small quanti~y of magnetite associated with chalcopyrite, found only a limited application in the direct detection: of copper mineralization. The IP survey was successful in outlining broad zones of low-grade mineralization but failed to indicate any high-grade targets at depth. In" pa~ticular the IP measurements did "not indicate an anomaly to be associated with the high-grade massive sulphide mineralization

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intersected by DDHl. In November 1972, BMR carried out Turam _and transient electromagnetic (ToE.M.) measurements over the same sulphide inters~ction. Since no anomalous response was obtained, despite the relatively shallow depth of the sulphide intersection, the body is probably of small extent.

The failure of all conventional surface methods to record a diagnostic anomalous response over known massive sulphide mineralization led -to the application of in-hole IP measurements and applied potential surveys in an attempt to trace extensions of mineralization.

4. GEOPHYSICAL TECHNIQUES

4.1 IP logging method

It was hoped that the down-hole IP measurements would extend the search for massive or disseminated sulphides to depths beyond the range of surfac~ geophysics by detecting mineralization narrowly missed by drilling.

IP measurements were made using McPhar frequency domain equipment operating at O.3Hz amd 5Hz. -Two logging probes were employed, one using lO-foot and the other 30-foot dipole-dipole electrode configurations. Down-hole readings were taken in both cases at lO-foot intervals. A detailed account of the method and instrumentation is givenby Gillespie (1972).

Conventional S-P, single-point resistance, and gamma logging were also carried out to supplement- the IP data and establish the physical properties' of the rock formations.

4.2 Applied potential method

The- applied potential technique _was used in an attempt - to establish the structure of 'known massive chalcopyrite mineralization encountered by drilling and to ascertain which of the different mineralized -intersections were interconnected.

Theoretical considerations. The potential .' at:- the plane surface of a uniform semi-infinite isotropic earth due to a point source embedded in that earth is given by:

v = . (1) . . . . . . . . . . --

where V = voltage

= resistivity

I = current

r = distance: to source



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In an area of flat relief, therefore, the equipotential lines at the surface will form concentric circles around the point source. Departures from this response pattern would normally indicate the presence of a conductor.

In practice, a current electrode is earthed directly in the exposed mineralized body. In this way, the whole of a conducting body is energized and its various parts attain similar potentials. Mapping the resulting potential distribution at the surface, therefore, provides valuable information as to the body's overall shape, dip, and relationship to other mineralized zones in the area. A return current electrode is placed at some remote pOint such that its influence ·on the potential distribution in the area under investigation is negligible.

Field procedure. Three selected for detailed potential method:

zones of mineralization were investigations with the applied

(1) A zone of high-grade massive chalcopyrite, intersected between 190 feet and 205 feet in DDH 1.

(2) A similar zone of massive chalcopyrite, intersected between 245 feet and 257 feet in DDH 8.

(3) A smaller' zone of chalcopyrite-hematite mineralization, intersected between 437 feet and 440 feet in DDH 8.

These conductive mineralized zones were energized successively and measurements made of the resulting surface potential distribution. In addition to this, measurements were made in ten drillholes to obtain a three-dimensional control over the potential distribution.

Surface potentials were intervals on grid lines originally survey (see Pl. 2). The down-hole in millivolts per ampere of source an arbitrary reference located M4/l5.

observed at 50-foot used for the magnetic

potentials were measured current with respect to at the observation point,

The applied potential survey was carried out 'with the same equipment as was used for the IP measurements. The McPhar IP transmitter was used to pass commutated DC current between the down-hole and remote -current electrodes. Surface and down-hole potentials were measured us'ing the IP receiver. An S-P meter was connected to the receiver to allow corrections for S-P effects to be .made, and to determine the polarity of the applied Voltage.. Porous pots filled with copper sulphate solution were used for receiving electrodes, necessitating the construction of a special probe for the down-hole measurements.

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The down-hole current electrodes consisted of lengths of copper tubing positioned in the mineralized zones and connected to the IP transmitter by insulated cable. The remote electrode was about 800 m south of DDH 1.

Topographic limitations. As the observed, voltage is inversely proportional to the distance from the source (equation 1), large topographic variations may introduce spurious potential gradients and distortions. The rugged relief of the Basin Creek area therefore, restricted the amount of information that could normally be derived from the mapping of surface potentials.

Although no practical terrain-correcting technique was available, theoretical potentials were computed using the exact distance of the observation point on the surface from the point current source in the drillhole~ A comparison of the observed surface ,potentials with the theoretical contours provided a means to differentiate between potential distortions arising from possible topographic effects and those caused by subsurface zones of anomalous conductivity.

5. RESULTS

5.1 IP Logging

The down-hole IP results are presented in Plates 3, 4, 5, and 6, together with the results of the conventional S-P, single-point resistance, and gamma logs.

DDH 1. The hole was drilled to 497 feet but was accessible only to a depth of 215 feet. However, the low water-table level precluded electrical logging above 125 feet and therefore significant background variations, could not be recorded. Despite this, the 10-foot dipole response does indicate a resistivity low of 10 ohm-metres in the massive sulphide zone e'ncountered between drilling depths of 190 and 205 feet. Similar resistivity lows are associated with minor chalcopyrite and hematite-magnetite ,veining in phyllite, although they are not accompanied by marked rises in percentage frequency effects (P.F.E.' s) • In the zone of massive'mineralization, anomalous P.F.E.'s were recorded but had' consistently negative values. Consequently metal fa'ctor values are not shown. Similar difficulties' in measuring meaningful P.F.E.'s were experienced in DDH 5, DDH 6, and DDH 8. This problem is further discussed later.

The single-point resistance log correlated well with the dipole-dipole resistivity profile and known chalcopyrite mineralization. These data were valuable in



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demonstrating that a strong resistivit~ contrast, in excess of 1:10, exists between the sulphide ~neralization and the surrounding host rocks. The S-P log, run concurrently with the resistance log, shows anomalous troughs in the vicinity of the sulphide mineralization. These anomalous values may be attributed to metallic minerals undergoing oxidation, implying continuity of the mineralizati9n to at least the base of oxidation.

The gamma log reveals only a limited correlation with the drillhole geology, but does indicate that the chloritic phyllite is more radioactive than the other lithological units encountered. It is interestin~ to note also that there is a marked absence o~ rad10activity associated with the massive chalcopyrite mineralization. A similar effect is evident in the gamma log of DDH 8.

DDH 5. This drillhole did no~ intersect any ore-grade mineralization. The IPprofiles were generally flat, with only minor amplitude fluctuations. The frequency effect values were all gener.ally less .than 5%. A poorly defined resistivity low centred at 385 feet reflects the presence of minor chalcopyrite and sphalerite mineralization occurring as veinlets throughout the section 362 feet to 403 feet. .As negative frequency effects were encountered with the' 30-foot dipole probe, only the 10-foot dipole probe metal factor values are shown.

The S-P voltages did not show any diagnostic variations and background resistances were, in general, too high to record. The gamma log shows a slight yet distinctive change in intensity on passing from' the coarse-grained tuff into the more radioactive phyllite.

The IP and S-P logs did not reveal any significant anomalies that could be ascribed to possible sulphide mineralization in the immediate proximity of:DDH 5.

DDH 6. The results obtained with the 10-foot dipole probe show three distinct resistivity lows in association with moderate to high P.P.E. values. The corres~onding metal factor anomalies are therefore thought to be 1ndicative of sulphide mineralization, although the presence of mineralization is not, apparent in the geological log. 'It seems probable that mineralization lies near the hole, but unfortunately it is not possible with the present mode of operation to ascertain in which direction~ The 30-foot dipole measurements gave unreliable negative P. F. E. • sand were unable to substantiate these findings.

The S-P profile shows three ill-defined lows which correlate with the anomalous zones indicat.ed: by the IP measurements. The ~amma log records a typically high level of gamma ray intens1ty in the chloritic phyllite but does

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not exhibit any significant variations in the volcanic breccia or tuff.

DDH 8. This dri11ho1e intersected massive chalcopyrite mineralization between 245 feet and 257 feet. A response to this is reflected" by a distinct resistivity low of approximately 10 ohm-metres, in comparison with background resistivities of approximately 1000 ohm-metres as measured by the 10-foot dipole probe. The P.F.E. measurements, however, could not be accurately determined and were consistently negative in the massive chalcopyrite mineralization. Several other smaller' IP/resistivity anomalies, such as the one at 437 feet, correlate reasonably well with scattered vein1ets of chalcopyrite in the volcanic breccia sequence. A fairly broad resistivity low centred at about 120 feet cannot be explained by the geological log and the absence of anomalous P.F.E.'s downgrades the" possibility of nearby conductive sulphides. The significance of the negative P.F.E.'s recorded with the 30-foot dipole probe in this zone is unknown.

The substantial resistivity contrast between the sulphides" and surrounding wall rocks did" not generally permit the use of the single-point resistance logger, which has a limited range of 0-200 ohms. This instrument was, however, modified for use in DDH 8" and the result is shown in Plate 6.

The S-P profile correlates moderately well with changes in lithology and shows typical troughs in the order of 100-200 mV over known mineralization. The gamma log records a fairly high level of radioactivity associated with the ch10ritic phyllite and a low level in the massive chalcopyrite. The significance of the absence of gamma ray activity in the zones of copper mineralization is unknown. This effect is worthy of further investigation as it may assist an Understanding of the metallogenesis.

Discussion of the IP results

The down-hole IP measurements were only partly successful in detecting previously unknown zones of mineralization. The inability of the instrument to measure accurate P.F.E. I S in" zones of massive chalcopyrite severely restricted its application and re1iabi1ity~ Difficulties were also experienced with high contact resistances and after logging DDH 8 further work with the IP equipment was discontinued.

A possible explanation" for the may lie with the high conductivity mineralization. It was recognized equipment th"at inducti ve and capaci ti ve

negative P.F.E.'s of the copper

in designing the coupling may exist


I I I I I I I I I I I I I I 'I I I I I I

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where current and potential cables are placed in the same hole (GillesJ?ie, 1972). However, for most practical purposes and ~n a variety of mineralized environments, such coupling is negligible compared with the ma~nitude of the received signal - particularly for dr~llholes which encounter moderately resistive intersections of - ore containing sphalerite or ,rock intervals which contain disseminated sulphides. In very low resistivity environments like those associated with the massive chalcopyrite in DDH 1 and DDH 8, inductive coupling may prevent the recording of meaningful readings. Further experimental work with the equipment is required to investigate this possibility.

5.2 Applied Potentiai

The applied potential results are presented as cont9ur maps of surface and down-hole equipotentials (PIs 7 to 12). Theoretical surface potentials. are presented in Plate 13.

Current electrode in DDH 1

. . .-Surface potentials: Plate 7 ~hows. the poten~ial d~str~but~on on the surface when current was ~ntroduced ~nto the ore-grade mineralization encountered between 190 and 205 feet in DDH 1.

The outer equipotentials are elongated with a major axis striking about north-northwest. This correlates well with the known geological strike, but is not thought to represent a· deeper extension of the sulphide zone. Possibly, the elongation reflects the presence of disseminated near-surface mineralization. Moreover, the potential values increase fairly rapidly in the immediate vicinity of the current electrode and the inner equipotentials become more circular. Thi$ shows that the mineralization richest in sulphide is relatively small, and that there are no prominent extensions of the mineral.ized zone.

The theoretical potentials (Pl. 13, Fig. 1) computed for the same point source contact in DDH 1 reveal that the slope of the terrain would normally displace the centre of the potential distribution at the surface some 50 feet northwards, this being the closest point to the source. A comparison with the observed equipotentials shows that this is not the case and suggests that the.sulphide zone in DDH 1, although small, may have a minimum strike length of the order of 50 feet in a southerly direction, or alternatively extend vertically upwards towards the ground surface.

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The distortion of the 500 mV/A contour near peg M6/13 (7N/2E) may be associated with the presence of a conductor not in electrical contact with the ene~gized mineralization in DDH 1. The distortion does correlate well with a known conductive shear zone between pegs M6/13 and M6/15 (PI. 2).

In view of the rugged terrain, no reliable information can be obtained from surface measurements on ·the dip or plurige of the sulphide zone •.

Down-hole potentials: Plate 8 shows the equipotentials in the vert1cal plane through line M8 approximately 250 feet to the north and line 4.5 N approximately 170 feet to the south of DDH 1.. .

The equipotentials in the section ~rough M8 do not centre around the massive chalcopyrite in DDH 8, and this mineralization, therefore, is not in electrical contact with the mineralization in DDH 1. In addition,the mineralization in DDH 8 distorts the l50mV/A contour in a manner expected of an unrelated conductive body by forcing the contour away from the mineralized zone. Instead the equipotential pattern centres roughly around the horizontal projection of the current electrode in DDH 1. In view of the low order of the potentials (only 450 mV/A) this potential maximum is not thought to represent a northerly extension of the sulphide zone in DDH 1 but can be explained as a simple geometrical effect.

Similarly the equipotentials in the vertical section through· 4.5 N do not centre around any known mineralized . horizon. In particular, the down-hole measurements indicate that the sulphides intersected in DDH 10 between 445 and 455 feet, although directly on strike, are not a continuation of the energized sulphide zone in DDH 1. These findings are of particular significance, since the geological evidence of a connection was ambiguous. The centre of the potential distribution appears to lie around a point at about 150 feet drill depth in DDH 5. This does not correspond to the horizontal projection of the current electrode and suggests a southerly updip extension of the mineralized zone in DDH 1. However, the low order of potentials measured. in both vertical sections supports the conclusions drawn from surface observations, in that the ore-grade mineralization in DOH 1 does not extend far either to the north or pouth of its known location.

Current electrode in DDH 8 (upper mineralization)

Surface potentials: Plate 9 shows the equipotentials observed on the surface of the ground when current was introduced into the massive sulphide mineralization

I ! .

\'1.--


I· 1 1 1 I I I I I I I I I I I I I I I I

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intersected in DDH S between 245 and 257 feet.

The pattern is dominated by a strong elongated trend· striking about north-northwest, and centred to the north of the mineralized intersection in DDH S. The inner equipotentia1s are curved (convex to the west) and appear to ref1~ct the shape of the mineralized zone. As indicated above the centre of this potential. pattern does not coincide with the vertical projection of the current electrode as expected, but is displaced some 70 feet to the north-northeast. To a large extent this effect can be interpreted by simple geometrical considerations: involving the severe slope of. the terrain, as shown· by Plate 13, Fig. 2. There are, however, no obvious surface conditions ~at would account for the observed elongation of the equipotential contours towards the north-northwest. This elongation is therefore attributed to a north-northwest

. extension of the mineralization.

Down-hole potentials: Plate 10 shows the potential distribution in the vertical plane through the traverse MS (Fig. 2) and through the profile 10.5 N (Fig. 1) some 170 feet north of MS.

Figure 2 shows that .the equipotential contours which surround the current source in DDH S alie considerably elongated in the bedding-plane axis and are flattened along the horizontal axis. The pronounced ellipticity suggests that the mineralization is well developed in the bedding-plane axis and possibly along strike.

Structurally it appears the energized sulphide intersection in DDH S is related to the two small mineralized zones intersected inDDH 9 at depths of 650 feet and 677 feet. This is partly confirmed by .the applied potential measurements, which, despite a potential gradient of about 1 VIA, do indicate a weak electrical· continuity. Either side of this proposed mineralized zone,' the potential values decreas.e rapidly, where country roqks of higher resistivity a~e encountered. Of particular significance is the marked change in potential gradient demonstrated by the increased spacing between the 2400 mV/A, 2200 mV/A, and 2000 mV/A countours. These e~uipotentials do not centre on the known su1phiede intersect10n but reflect the presence of a broader conductive zone between drillin9 dep~hs 100 and 247 feet. The IP measurements for th1S dr1llhole also indicate a broad unexplained resistivity low between 90 and 130 feet. These observations suggest that· the massive sulphides intersected in DDH S could be part· of a larger plunging sulphide mass located between DDH:S and DDH 4. Such an interpretation would also be compatiple with the surface distribution of potentials. .

I~

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Figure 1 shows the equipotential pattern in the vertical plane through· DDH 4 and provides additional evidence for the interpretation given above. The equipotential contours do not centre on the horizontal projection of the current electrode,. as expected, but on a point about 80 feet uphole of this position. There is no indication of mineralization at this depth in DDH 4, but in view of the fairly high potentials, the mineralized horizon cannot fall far short of this point. A line connecting the potential distribution centres between the two' verbical planes suggests a southerly plunge of between 15 and 200 with the horizontal. .

Current electrode in DDH8 (lower mineralization)

Surface potentials: Plate 11 shows the surface distribution . of potentlals when current was introduced into a small stringer of chalcopyrite mineralization intersected at a depth of 437 to 440 feet in DDH B.

The equipotential distribution shows a similar pattern to that presented in Plate 9. The outer equipotentials, apparently unaffected by the energized Zone of mineralization, are almost circular. The inner equipotentials however are curved (convex to the west) and have an elongated trend striking approximately north-northwest. The centre of the potentials potential distribution is displaced about 120 feet to the north of the vertical projection of the current electrode. This displacement is only partly explained as a geometrical effect caused by the slope of the terrain. Computed potentials, assuming a point source, indicate a possible' shift downslope of 170 feet towards the northeast as shown in Plate 13, Fig. 3. It seems likely therefore that on the basis of surface measurements alone, the mineralization does extend northwards of the intersection in DDH B.

Down-hole potentials: Plate 12 shows the equipotentials in the vertlcal plane through traverse MB (Fig. 2) and through the profile 10.5 N (Fig. 1) about 170 feet to the north of MB.

The equipotentials in Figure 2 are elliptical, with a near vertical major axis passing through the current electrode. This suggests a thin vertically dipping conductive zone of mineralization. A similar pattern is evident in Figure 1. The potential maximum, however, does not correspond to the projection of the current electrode, but coincides exactly with a 5-foot wide mineralized zone intersected in DDH 4 at a depth of 360 feet. The horizontal projection of the current electrode is more than 70 feet away. Although the potential maximum is only 1.7 VIA, the

l..t


I I

" I I I I I I II ( " ;-v

I I I I I I

tl II

I I I

" ,

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position of the centre strongly indicates that this mineralized section in DDH 4 has direct electrical continuity with the section in DDH 8, where the energizing electrode is situated, and fully supports the earlier conclusions, drawn from the surface observations, of an extended mineralized zone striking north-northwest.

The potential maxima in Figures 1 and 2 occur at depths of 437 feet and 360 feet respectively. This difference can be 'explained by assuming that the mineralized zone has a small plunge towards the south, in the order of 130

• It is interestin~ to note, that in Figure 2 the 500 mV/A contour is not1ceably distorted by the conducuive sulphides encountered between 245 ,and 257 feet in the upper portion of DDH 8, showing that this is, as expected, an unrelated zone of mineralization.

Possible effects of anisotropy

The geophysical evidence indicates that the major extensions of the mineralized formations coincide with the strike and dip of the country rocks. It seems probable, however, that the elongation of the' equipotentials, attributed to the influence of mineralization, may be due in part to a triaxial anisotropy in the barren country rock. This effect has not been fully investigated in the present survey, but in view of the large resistivity contrast between the host rocks and the conductive sulphides, the anisotropic effect should not detract significantly from the results';- ,

'6. CONCLUSIONS

The down~hole ~p techn~que was partly successful in indicating conductive and mineraiized zones, but because of adverse geo~h~sical conditions and instrumental problems, found only a l1~ted application in the present survey.

The applied potential measurements 'were found to be an effective tool for . tracing the extent of the chalcopyrite mineralization. The ore-grade mineralization in DDH 1 was shown to be unrelated to the mineralized horizons in DDH 8 or DDH 9 and appears to be a relatively small occurrence with only a limited updip extension to the south. In contrast, the two mineralized zones in DDH 8 appear to have prominent extensions to the north of their present intersections.

To test the proposed southerly extension of the massive chalcopyrite encountered by DDH 1, a drillhole should be sited not more than 50 feet to the south of DDH 1,

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to intersect a target approximately 140 feet below the grid point 6 N/3.4 E. A suitable collar position for a drillhole of inclination 450 and bearing 242 0 would be at 6 N/4 8 E. A s~cond drillhole sited at 9.8 N/6.4 E, inclined at 45e and with a bearing of 245 0

, would effectively test the postulated northerly extensions of the two main mineralized zones in DDH 8.

The rugged terrain and experimental nature of the measurements did not permit more than a qualitative evaluation of the applied potential data. Despite these limitations, quite definite results were obtained and it seems possible that with the further development and application of the method, quantitative interpretations may be carried out.

GILLESPIE, P.J., logging tests A.C.T., 1971.

7. REFERENCES

1972 - Down-hole induced polarization at Currawang, N.S.W. and Kowen Forest,

Bur. Miner, ResQur. Aust. Rec. 1972/29.

JOHNSON, B.T., 1972 - Description and interPretation of surface magnetic survey, Basin Creek No.1 Prospect, E.L. 20'0, Tumut, N.S.W. RUE. submitted to A.O.G. Minerals pty Ltd, 29 May 1972 (unp I~shed). .

TYNE, E., 1971 - Induced polarization survey within MEL 200, near Tumut, N.S.W. Geol. Surv. N.S.W. Rep. No. GS 1971/722 (unpublished).



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I 200 FEET

-+--@)OOHI2

8 9t

~ I" ~ ........ 10 10 H

-------------------

I'()

W 20

~ )... -.. ~ ~

...J ~ '-

~ .... 10 a.. ~

C) t...J t...J ~ ~ lI,j 0 I

40

-10

1000

.... ::....(;) ~ .... ~ 100 ~S;:h: 'O:ti:::~ ~~ I

10 ~t3t ~ C)

'-

600

-.. ~ 400

~ t...J

~ ~

~ 200 ~

0

0

~ e: '--...J

~ I...:

~ I...: -100 C) Q., I

lI"

~ <I)

-200

"' .... -<::

"'-Cl::: 0-02 ;::;

...:..: ~ C) ...... .... ~ ~

~

~ 0,01

~ ~ ~

0 0 40

::.... ~ C)

c5 t5

- - - - -...

J

I 80

.~ .- . / ...... ", .'. I ~ I I \. I

120 -- 160 .~ f 200

DEPTH (ff J ...

80 120 160 200

DEPTH (ffJ

'" '" ,.,

- - - - - -

",.-- • ___ 10' DIPOLE

30' DIPOLE READINGS NOT POSSIBLE OWING

TO INSUFFICIENT DEPTH OF DDH I

.••••. •••••••••• INO/CATES NEGATIVE P. F. E.

C/)

~ :::> C/) w et:

:I: 0 (!) 0 z

(!) (!) 0 ...J

LEGEND

~ PHYLLITE

L:3 SCHIST

SULPHIDES

m BRECCIATED ZONE

MINOR CHALCOPYRITE MAGNETITE HEMATITE VEINS

- - - - - '-- - -

I I'(II

....... 10 10 ......

1\..-\Q

""-~ ~

~ ~ a ~ ~ ~

~ a I.l I:l

~

- )

>.. I-.... ...... ::::.. --.... j::: \r) \r) ~ (;) I-....

~ ~ I-.... I ~ ~ l<.J =t. Cl:: C) "'< "-Q Q "'<

Cl:: i:::' C)

I-.... C) '-.l C)

~ It..

'" ---J \r)

~ C) =t.

l<.J ~ ~ "-

~ ~ ---J

~ ~

~ C) Q I

It.. ---J It.J \r)

20

10

a

-10

10000

1000

100

.-. ,;., .-., .-. & ,-.-.- -.-.'.-.-.-.~~~ ~.~, ) ~ .; '.-.-.-. __ .---_. ·--'·.L·,·'.""'-.- ...•. • . .•... •...•.. ........ .. ·r .............................. .

--T------r--- - ,-----r---r-------l--T---- ----r----,- I I -,-=--o.--;r.:- 'I •• ~ ••• I I I I I I I I I I 40 80 120 160 200 240 280 ··.i 32~ 360 400 440 480 520

DEPTH (ft)

• . . ..•...• ~ . ... . .-. • 1. \ -. • .... ....... ::: .. ~.-u ........ · .......... /" · ......... ~.~ .• r.:.:, .• .•..•...• / .'( ............ - •.•...• ." . .. . ..•.. . ..•...•... -./

I 560

10~--~-~--~---,--.---,---,---,---,---_.---_,--,_--_,--,_--_,---,_-_.--,_--_,--,---,---_,---,---,--,---,-----,---,

10

100

1000

-100

-200

-300~--~----~--~--_.--~----._--~--_r--~----._--~--_.----._--._--_r--_.----._--~--_.--_,----._--,----,----,---,----,---,---,

O~----._--_.-----.----,_--_.r_--_,----._--_.----_,----,_--_,r_--_rl----,-----'I----,----.I----~----'I ----.----.1-----.----'1----,-----'1----,-----'1 ----,----1 o 40 80 120 160 200 240 280 320 360 400 440 480 520 560

DEPTH (ft)

o 0 0 000 0 0 0 0 0 000 0 0 0 0 0 000 0 0 0 0 0 0 0 0 000 0 0 0 0 0 0000000000000000000

Cu Zn Pb

veins only

To uccornpany Record No 1974/67

PLATE 4

-.-.- 10' DIPOLE

•••••••••••••• 30' DIPOLE

METAL FACTOR FOR 30'

DIPOLE NOT PLOTTED OWING

TO NEGATIVE PFE's

LEGEND

DDH LOGGING

PHYLLITE

TUFF

MINOR SULPHIDES

(VEINS ONLY)

AGGLOMERATE

BRECCIATED ZONE

5 RESULTS

155/87-120

--.... ~ '--

h... I...l

~ ~ )... I..)

e3 ~ L...J

~

)...

h. ..... :::,. --.... .....

tI) h. tI)

~ iJ)

~ ~ h. , ~ ~

C)

& '--

"<

It f::' C)

I-- C)

~ C)

~ '"'-"-

--.J tI)

~ C) ::t::

~ ~

--.... ::".

~ -.J

"< ...... h. ~

~ C) Q.. I

'"'--.J L..J tI)

--.... ....

-<::

"-It ~ ~ C) ...... h.

~ t:::l C§

"<

~ "< ~

20

10

o~ -I ,- .. _, T

I 40 80

-IOJ -20

10 000

1000

100

10

100

1000

200

0

-200

.:.... ;.\ .•.. ".,:..... •.. . - ...... e-,' I. ."", . ." ..... • •

1

• _' ............ -...... . .• -.- •. -.-, ..•..•.. , ._,.' ._t. ...". ...... . e_. ___ ·- . . ' ..., •... -:'" _ - ............ . ---.-------.--~'I -=----'1 - T-· ~~ -r-:--. I' I -----r- I'. . 1 lit

160 200 :. 210 280 326..: 360 400 •. k.: l'w : 440 120

· . : : DEPTH (ft) · . · . '. '. •

. . · . · . .' •

....... I·" ._.-._ ./ \ • ::-:-.-e, /· .......... ,t:I~,. .'-= •. .:,.,. .......... ,..;,-:;/....... . •..•. " ..... ;.. •... " •.. ,-...... ........ . . '-. •...•.. . .' ...... "' .•... ....

_.- ....... ..... \. .......

1 480

-300-r----,----r----.----.----.----.----.----,----.----.----,----.----.----.----.----,----.----,----,----,----,----,----,----,----,

003

002

0-01

01----.----,----,----.---,----.----,----,----,----,---.----,-- I 280 o 40

000 000

000

80 120 160 200 240

DEPTH (ft)

v v v v V v V V V v V V V v V V V VVVVVVVVVYv VVVVVVY

v v V v V v v v v v v v V v v v v

I 320

I 360

1 400

00000 0 000 o 0 000 0 0 0 0

000000 0 00

I 440

1 480

To accompony Record /101974/67.

....... -.-""" ..............

10' DIPOLE

30' DIPOLE

METAL FACTOR FOR 30'

DIPOLE NOT PLOTTED OWING

TO NEGATIVE PFE's

L E G END

~ PHYLLITE

~ o ~

o 01....0 0 TUFF

rnTIIJ JI DISSEMINATED

PLATE 5

SULPHIDES

~ v v VOLCANIC BRECCIA v v v

I ~ 0601 o t:> 0

CONGLOMERATE

DOH 6

LOGGING RESULTS

155/87-121

).., ..... .... ~

i::: Cr)

~ ~ .....

~ Il::

~ Q; ~

30

20 ....... ~ '-..... 10 \.)

~ ~ 0 ).., 40 80

~ ~ -10 •.. :

• .-., f·-·' ..... " J \ .• '. • I. .,.f'" . ..~ ... I·-~· ... ~ A,...·'. : ... .0:., / '\ ..... -. ._. .... :' ...... ". ~.A".~.~." ,........ :;.. ......... ~.""...... . ..... ~.~ ..... .I,..

I . I. .• I I I I' .. I '" I I I I I T I I 1 I '1 --'----'1 ::28(].·· 320 360 400 440 480 520 560 600 640

DEPTH (ff)

~ l4J

~ -20

-30 .; . :

100000

10000 ....... \I)

~ ..... 1000

~ I

~ 100

C)

'-10

...... ...... \ .... ; \ .... / .. -.. / . "....... ....." .-. ,..... ...... . / ., . .-.-. _.-.,.,.-.-.-.-. I," ." :!-•....•...•.. :;:., f' .. , ...... :."".~.~':':./ \ .. .... _." ...... \ /."'.-. ......... .•. \: ......•... \... ......,... ...... ,.. ..... . .. .. .. ... " .. .'. ' •. . ... . ... . '.' . 'e. , ....... ,.... ,.' ... ' '. . ..... . --.",.. ..•.. .-. :

: .

oJi! •

2500

2000

---~ :t ~ 1000 l4J \.) <!: ~ 500 Cr)

~ ~

100

200 ....... ~

~ -.J ~ i::: <!: ~ 0 C) 0... I

Li..

~ Cr)

-200

0·04

-... '- 0'03 ~

"-Il:: I:: '-

~ C) ;:: 0'02 ~ Q

~

~ ~ ~ \!) 001

O~---.----r---,----,---,---,----,----,---,----r---,----,.--.----,---,----,---,----,---,----,---,----,---,----,----r---,----,---,----r---,----r---I

o 40 80 120 160 200 240 280 320

DEPTH (ft)

360 400 440 480

" Sulphides /

veins only

520 560 600 640

7b accompany Record No 1974/67

-.-.- 10 DIPOLE,

•••••• • • •••••• 30' DIPOLE

LEGEND

~ PHYLLITE

~ o 0 TUFF o 0

SULPHIDES

~ AGGLOMERATE

D v v VOLCANIC BRECCIA v v v

DDH 8

LOGGING RESULTS

PLATE 6

155/ B 7- 122

~--------------~--~-

-(J1 (J1

........ [D

-..J I

I\) ()J

70 accompany Record No. 1974/67

I:3N

9

8

7

:3

2N

NEW GRID BASE LINE

I o I

IE 2 :3

---© VERTICAL PROJECTION OF DRILLHOLE ON SURFACE

~ MINERALIZED INTEPSECTION PROJEC TED ON SURFACE

4

+ VERTICAL PROJECTION OF CURRENT ELECTRODE

5

I 50

10 I

o I

I o

6E

10 I

©DDH 4

20 I

30 I

I 100

SqRFACE POTENTIA~S

40 I

50 I

X MAXIMUM SURFACE POTENTIAL EARTHING IN DOH II,T DRIL"L - DEPTH 190'-205'

CONTOUR INTERVAL -IOOmV/A

60 METRES I

I 200 FEET

I

HEIGHT R L 1650

I

1600

I

1550

I

1500

I

1450

I

1400

I

1350

1 1300

1 1250

I

1200

I

i 150

I

1100

I

1050

I

HEIGHT R.L 1750

I

1700

1650

I

1600

1550

I

1500

I

1450

I

1400

I

1350

I

1300

I

1250

To accompany Record No 197£'" 67

WEST

--I HORiZONTAL PHOJfCTlON OF DRIL.LHOLES

-~- MINERALIZED INTERSECTION

+ HORIZONTAL PROJFCTlON OF CURRENT

EUCTRODE IN DDH I

PLATE 8

EAST

Fig.1 POTENTIALS IN THE VERTICAL

SECTION THROUGH M 8. EARTHING IN DOH I AT i90'-205'DRILL DEPTH

CONTOUR IN TER VA L 50 m V / A

EAST

DOH 10


SECTION THROUGH 4·5 N EARTHING IN DOH 1 AT 190'- 205' DRILL DEPTH

10 0 10 20 30 40 50 60 70 80 90 METRES L...J---L I I 1 I L I I....J

,---,---·,'--'-----'-1 ---,----rl ---,------"

50 a 100 200 300 FEET

N_B. ALL MEASURMENTS IN FEET

155/ B7-124

--------------------

CD. (J1 (J1 ........ CD -..J I

I\) (J1

@DDH 7

10

9

@DDH 5

4N ________ ~ ________ ~L_ ________ ~ __________ _L __________ _L __________ ~ __________ L_ ________ ~

o IE 2 3 4 5 6 7 8E

I NEW GRID BASELINE

I

To accompany Record No. 1974/67

~ VERTICAL PROJECTION OF DRILLHOLE

~ MINERALIZED INTERSECTION


X MAXIMUM SURFACE POTENTIAL

CONTOUR INTERVAL - 100 m V /A

SURFACE POTENTIALS

EARTHING IN DDH 8 AT DRILL- DEPTH

10 0 10 20 30 40 50 60 I'v1ETRES I I I I I I I I

I I I 50 0 100 200 FEET

. "

WEST

I

HEIGHT R.L. 1700

I

1650 1\)

I ~

1600 ~

I

1550

I

1500

I

1450

I

1400

I

1350

I

1300 I

475 I

1250

I

1200

, 1150

I

1100

, 1050

WEST

I

HEIGHT R.L. 1650

, 1600

, 1550

I I

1500 \ \ 1\)

I C) 1450 ~

, 1400

, 1350

, 1300

1250

1200

, 1150

, 1100

, 1050

HORIZONTAL PROJECTION OF DRILLHOLES

~ MINERALIZED INTERSECilON

, 564

I

\ \ \

U1 ~ ~

\ \ \ \ \ \ \ \ \ \ \

\ \ \ \ \ \ , , , I I I , I I I I

I I I I I , ,

I \ I

PLATE 10

EAST

/ DOH 7


SECTION THROUGH IO·5N. EARTHING IN DOH 8 AT 245- 257 DRILL DEPTH

OVER 1350 mV/A

OVER 1370 mV/A

CONTOUR INTERVAL 100mV/A

EAST

/" DOH 9


SECTION THROUGH M8. EARTHING IN DOH 8 AT 247'- 257' DRILL DEPTH

\ I \ , CONTOUR INTERVAL 200 mV/A

\ I \ I ' ... ,/

+ HORIZONTAL PROJECTION OF CURRENT 1087

ELECTRODE IN DOH 8

To accompany Record No 1974/67

I 50

10 0 10 20 30 40 50 60 70 80 90 METRES I, I I 1 I I I I I

I o

I 100

I 200

N.B. ALL MEASURMENTS IN FEET

I 300 FEE T

155/B7-126

--------------------

To accompany Record No.l974/67

6

o

NEW GRID

BASE LINE I

IE 2 3 4

VERTICAL PROJECTION OF ORILLHOLE



X MAXIMUM SURFACE PO TEN TAL

CONTOUR INTERVAL - 50mV/A

I 50

10 0 I I

I o

5 6E

10 20 30 40 50 60 METRES I I I I I I

I I 100 200 FEET

SURFACE POTENTIALS EARTHING IN DOH 8 AT DRILL DEPTH 437'-440'

"'U r l>

.-i rTJ

WEST

I

HEIGHT R.L. 1700

I

1650

1600'

1 1550

& "l-

I

1500 I I

I I 1450 I

I I 1400 ,

I I I

1350 I I

1 I 1300 ,

I ,

1250 \ \

I

\ 1200

\ 1 \

1150 \ \

1 \ 1100

I 1050

I 1000

1 9:>0

---f HORIZONTAL PROJECTION OF DRILLHOLES


+ HORIZONTAL PROJECTION OF CURRENT

ELECTRODE

To accompany Record No. 1974/67

I

1087

I 50

,,--/

~--

I I

I I I I I

<::J <::J <::J "l-

\ g MINERALIZATION

<::J -.... -....

CONTOUR INTERVAL IOOmV /A

:l<: W W a:: <.)

z (f)

<! CD

CONTOUR INTERVAL AS SHOWN

10 0 10 20 30 40 50 60 70 80 90 METRES I 1 I I I

I o

I 100

I 200

N.B. ALL MEASURMENTS IN FEET

I 300 FEET

PLATE 12

EAST

DDH 7


SECTION THROUGH IO·5N. EARTHING IN DDH B AT 437'-440' DRILL DEPTH

EAST

DDH 9


SECTION THROUGH M 8. EAFTHING IN DDH 8 AT 437'- 440 DRI LL DE PT H

155/B7-128

II f\[

7

Fig.1 EARTHING IN DDH I AT

DRILL DEPTH 197'

@DDH 2

CONTOUR INTERVAL IOOmV /A

3N ________ L-________ -L __________ ~,----------L----------L----------L'----------L---------~I IE 2 3 4 5 6 7 BE

o I

NEW GRID BASELINE

13 N

12

II

10

9

8

7

6

Fig.2 EARTHING IN DDH 8 AT

DR ILL DE P T H 252'

@DDH'I----,.;..-. ....

CONTOUR INTERVAL 50mV /A

13

8

~ 6

,., o o

\

/ MINEHALIZATION

/::~~ ~.~;.>;~~,

. ~~~.:~. : •.

Fig. 3

@DDH I

EARTHING IN DDH 8 AT

DRILL DEPTH 435'

@bOH4

~ OVER 640mV/A

CONTOUR INTERVAL 50mV/A

PLATE 13

5N ________ L-________ _L __________ ~ ________ _L __________ ~ ________ _L ________ ~

2

__ -LI ________ ~I __________ LI ________ ~

6 7 B 9E 5N ________ L-________ -L __________ L' ________ ~ __________ ~I __ __

3 4 5 2E 3 4 5 6 7 8 9E

IE

--@VERTICAL PROJECTION OF DRILLHOLES

~ MINERALIZED INTERSECTIONS


X MAXIMUM SURFACE POTENTIAL

I 50

o I

NEW GRID BASELINE

10 0 10 20 30 40 50 60 METRES 1 I I I I ! I I

I o

I 100 200 FEET

THEORETICAL SURFACE

POTENTIALS

155/87-129

Documents

BUREAU OF MINERAL. ,RESOURCE·S,· GEOLOGY AND …IP, Single-point resistance, SP and gamma logs, DDH1. IP, SP and gamma logs, DDH5. IP, SP and gamma iogs, DDH6. IP, Single-point resistance,