detrital gold assessment: drilling, nasivi delta, tavua, fiji

DETRITAL GOLD ASSESSMENT: DRILLING, NASIVI DELTA, TAVUA, FIJI

17 November – 4 December 1999

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[SOPAC Technical Report 289 – Wong & Lum]

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TABLE OF CONTENTS

Page

SUMMARY...................................................................................................................... 5 ACKNOWLEDGEMENTS ............................................................................................... 4 OBJECTIVE.................................................................................................................... 6 INTRODUCTION ............................................................................................................ 7 Climate ..................................................................................................................... 7 Vegetation ................................................................................................................ 7 PHYSICAL SETTING...................................................................................................... 9 Access...................................................................................................................... 9 PERSONNEL INVOLVED............................................................................................. 10 GEOGRAPHIC LOCATIONS........................................................................................ 10 DRILLING PROCEDURE – SAMPLING TECHNIQUE ................................................. 10 SAMPLE PROCESSING .............................................................................................. 13 RESULTS ..................................................................................................................... 13 CONCLUSIONS............................................................................................................ 14 RECOMMENDATION ................................................................................................... 14 REFERENCES ............................................................................................................. 15

LIST OF FIGURES Figure 1. Locality map showing area drilled.................................................................... 8 Figure 2. Locations of drill holes ....................................................................................11

LIST OF PLATES Plate 1. Part of survey area covered by sugar cane fields .............................................. 7 Plate 2. Part of road leading to survey area covered with flood water ............................ 9 Plate 3. Drill rig in operation.......................................................................................... 12 Plate 4. Mechanical auger in operation......................................................................... 13

LIST OF APPENDICES Appendix 1. MRD-SOPAC core description.................................................................. 16 Appendix 2. Daily log narratives.................................................................................... 38 Appendix 3. Drill logs .................................................................................................... 40

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ACKNOWLEDGEMENTS The Government of the Republic of Fiji funded the survey with additional funding from the Government of Taiwan. Mineral Resources Department (MRD) and South Pacific Applied Geoscience Applied Commission (SOPAC) provided the logistic support for the survey. Thanks are due to the Tui Tavua and landowners of the Nasivi Delta area for granting us permission to work in the area. We would also like to acknowledge the contribution made by Inosi Yabakivou and the drilling staff, Apenisa Raikabula, Josevata Turaga and Altaf Hamidullah, namely for their hard work in the field.

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SUMMARY

Results of the EM survey conducted in 1998 in conjunction with the resistivity depth profiles were successfully used to define the different lithological boundaries based on resistivity of the substrate. The resistivity depth profiles defined at least five lithological units of varying thickness in the study area, which were confirmed by augering. These are topsoil, clayey sediment, fine sand/gravel in a clayey matrix, saturated zone and hard rock. The areas of low conductivity (sand/gravel) are the prospective areas for gold accumulation and are chosen as the target areas. A map based on the conductivity shows that this target area covers approximately a third of the study area. Eight sites in these target areas were drilled by rotary method using the Mineral Resources Department’s Tone Top 250 drill rig, and samples were collected at one-metre intervals and logged. Eight holes of depths up to 51 m were drilled. Gold grains were found in three panned concentrates of two drill holes, TV99/5 (35-36 m) and TV99/8 (3-4 m, 13-14 m). Panning on site at drill hole TV99/4 also showed a gold grain each in the 16-17 m and 17-18 m intervals. In each case the gold grain was found in coarse sand associated with sub-angular to sub-rounded basaltic pebbles of various sizes up to 1 cm. The drilling was not a total success in terms of sample recovery. Drilling mud was used and it removed fine gold grains. However drilling confirmed the existence of gravel beds in the area and also the existence of gold grains. The gravel beds vary in thickness and were found in different depths for each drill hole. The gold grains are anhedral. Further work to determine the extent of detrital gold in the area is recommended, work

to include geophysical survey to locate buried river channels and further drilling. Drilling is only to proceed if the drilling technique and sample recovery are improved greatly.

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OBJECTIVES

The primary objective of the Detrital Gold Resources Survey in the Nasivi Delta area was to assess the placer gold potential in the sediments of the delta, particularly the gravel beds, by drilling, using the MRD-owned Tone Top 250 drilling rig. To meet this objective eight holes were drilled. Field programme aims included: • conducting a drilling programme in target areas identified from the EM and resistivity

survey conducted in the Nasivi Delta, and • assessing the placer gold potential of the samples collected, by panning and

microscopic examination of the heavy-mineral concentrate. This work was carried out to fulfil the requirements of Task FJ97/02, and the field programme was conducted from 17 November to 04 December 1999.

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INTRODUCTION

This drilling survey was undertaken to assess the potential for detrital gold in the area within and adjacent to the Nasivi River delta on the north coast of Viti Levu, in the vicinity of Emperor Gold Mines in Vatukoula (Figure 1). This initiative is a result of a recommendation of a review of placer gold potential of Nasivi Delta area following geophysical work conducted earlier. The Nasivi Delta area was chosen because it is geologically favourable and it is near a known goldfield, the Tavua Goldfield. As the Nasivi River flows through the mineralised area, it is likely that both detrital gold and gold-bearing rock fragments have been washed down the river to accumulate in the delta and adjacent offshore areas.

Climate The survey area lies on the north coast of Viti Levu and like the rest of Fiji enjoys six months each of “summer” (hot and wet) and “winter” (cool and dry). Average rainfall for the area is 1860 mm per annum, and rain falls generally throughout the wet season (November to April), which also happens to be the cyclone season. The Nasivi Delta area is prone to flooding and flood levels may reach at least 2 m. Vegetation Much of the study area is covered by sugar cane fields. Sugar cane is normally harvested during June to December. Therefore the later part of this period provides the best working period in the area because of the absence of sugar cane.

Plate 1. Part of the survey area covered by sugar cane fields.

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Figure 1. Locality map with caldera geology of Nasivi Delta.

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PHYSICAL SETTING The Nasivi River delta lies approximately at 177

o40' E and 17

o33' S (see Figure 1) on

the northern coast of Viti Levu, close to Tavua. The alluvial sediments of the dominantly subaerial delta are derived from the Nasivi River that drains the Tavua Caldera, which hosts the Vatukoula gold deposit approximately 10 km upstream from the present mouth of the river, which flows into an embayment, the Taba-Ko-Nalomo Passage at the western extent of the survey area. The approximate dimensions of the delta are 5 km east-west, and 3 km north-south. Water depths in the main channel vary between 5 and 14 m. The delta area is surrounded by extensive and well-developed coral reefs, Sali Sali and Ve Drala reefs to the north, and Olaca Reef to the east. Olaca Reef separates Taba-Ko-Nalomo Passage from Natobu-Drauivi Passage, in Tavua Bay. These three reefs are exposed at low tide and are separated by deeper water with average depth of 15 m. The Nasivi Delta flood plain is generally low lying along the coast, grading into undulating countryside. The terrain in the interior is hilly and deeply dissected. Rock exposure is poor and weathering is intense. Most of the land is cultivated for sugar cane. Access The area is reached from the tar-sealed Kings Road and from Tavualevu Village and over an Irish crossing except in flooded conditions. It is serviced by numerous all-weather cane roads. During heavy rain the cane roads are often flooded in places, but are accessible to traffic. There are also numerous boat landing sites along the coast. Plate 2. Part of road leading to survey area covered with flood water.

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PERSONNEL INVOLVED The drilling project was undertaken by personnel from MRD and SOPAC. MRD SOPAC H.L. Wong Marine Geologist Jackson Lum Marine Geologist Isei Rayawa Technical Officer

II Sekove Motuiwaca

Geological Technician

Inosi Yabakivou Technical Officer II

Setareki Ratu Geological Technician

Apenisa Raikabula

Drill Crew I

Josevata Turaga Drill Crew II Altaf Hamidullah Drill Crew II

GEOGRAPHIC LOCATIONS

Drill-hole locations were fixed with a Gamin Rover GPS with Differential Del Notre with reference to the 4600 GPS receiver which was set up at the Tavua Reservoir (WGS 84 reference point LAT 17o 25’ 55.7453”S, LONG 177o 51’ 46.0094”E, height 115.8980 m).

DRILLING PROCEDURE SAMPLING TECHNIQUE The departmental TONE TOP 250 drilling rig was used to drill eight vertical holes in the targeted area (Figure 2). “NW” size drilling rod was used. The specifications for this drill rod are: 66.7 mm - Outside diameter 57.2 mm - Inside diameter 24.2 kg - weight per 3 m As drilling progressed the hole was cased every six metres using “HW” size casing. Casing continued where possible. The specifications of the casings are: 114.3 mm - Outside diameter 101.6 mm - Inside diameter 50.5 kg - weight per 3 m. The bit used is the 4 1/2” Rockroller bit.

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The drilling method used is the rotary or rotational one, which is a water- circulation drilling method. A sump, approximately one cubic metre, was dug near the drill site and was filled with water, which was used for drilling purposes. As drilling proceeds, water is pumped down and brings the drilled material up. For each metre drilled, the water plus sample is collected in buckets and the water is then poured out. The samples are collected in labeled bags and logged on site. The logging is confirmed on return to the office when the samples are microscopically examined. This drilling method is not the best method as sample recovery at times was very poor because of poor circulation of water down the hole to bring the samples up.

Plate 3. Drill rig in operation. In the foreground is the sump filled with water The methodology of sample collection and the use of drilling mud is not ideal, but under the circumstances there was little choice as the drilling method used was the best the drill crew could do. Generally the drilling mud removed fine- grained gold when the muddy water is tipped out from the buckets to leave the samples. As drilling proceeded, the holes were cased, every six metres, to prevent contamination of the samples. The length of casings used in each hole varied. Furthermore, the weather was rather bad and it hampered the drilling. Hence all nine holes could not be drilled in the time we were in the field. Mechanical augering was used at TV99/4 where gravel beds were near the surface to a depth of six metres. A sample was collected for each metre and panned on site. None of these augered samples showed gold when panned.

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Plate 4. Mechanical auger in operation.

SAMPLE PROCESSING Samples collected were split into two portions, one for the archive, and the other to be panned. Panning took place under the bridge of the Naboro Creek. The panned concentrates were then inspected for gold particles using a hand lens and packed in labeled packets.

RESULTS

Eight holes of depths up to 51 m were drilled (Appendix 1). Gold grains were found in three panned concentrates of two drill holes, TV99/5 (35-36 m) and TV99/8 (3-4 m, 13-14 m). Panning on site at drill hole TV99/4 also showed a gold grain each in the 16 -17 m and 17-18 m intervals. Observations of the gold grains under a microscope of 20X magnification showed that the grains are anhedral. In every case the gold grain was found in coarse sand associated with sub-angular to sub-rounded basaltic pebbles of various sizes of up to 1 cm. Drilling has shown that gravel beds are present at each drill sitee. They vary in thickness and occur at different depths. Drill logs for each hole showed that gravel was found with coarse sand within one to three metres below surface, except for TV99/2, where gravel was found at a depth of 12 metres (Appendix 3). A total of twenty-three metres of gravel/coarse sand was found in drill hole TV99/1. Drill hole TV99/2 had the least gravel/coarse sand, with only two metres found in the forty-eight metres that was drilled.

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CONCLUSIONS

The drilling was not a total success in that sample recovery was poor at times. However, drilling confirmed the existence of gravel beds in the delta plain, and the existence of gold in the area. 1. Despite the poor sample recovery aggravated by bad weather, gold was

recovered from three of the eight drill holes, TV99/4, TV99/5 and TV99/8. The gold was not confined to any specific depth.

2. The gold grains recovered from samples are anhedral in shape. 3. The gravel beds were found at different depths and vary in thickness. In all holes

except for TV99/2, they were found within one to three metres from the surface. 4. The composite thickness of gravel found in each drill hole ranges from two

metres (TV99/2) to twenty-three metres (TV99/1). 5. Generally drill holes closer to the sea encountered less gravel than those near

the main river. 6. The methodology of sample recovery and the use of drilling mud is not ideal, but

under the circumstances it was the best option the drilling crew could offer. Generally the drilling mud would remove fine gold grains.

RECOMMENDATIONS The fact that gold has been found, despite the drilling not being a total success in terms of sample recovery, warrants further work in the area. Therefore, to determine the extent of detrital gold mineralisation in the area it is recommended that further work be done, to include geophysical survey (seismic refraction) to locate buried river channels and further drilling. Drilling should be done only if the drilling technique and sample recovery is improved greatly.

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REFERENCES

Blatchford, A. 1953. Geology of the Tavua Goldfield, Viti Levu, Fiji. Australasian Institute

of Mining and Matellurgy, Proceedings 168-169:13-51. Cohen, Em. 1962. Revised geology of the Tavua Goldfield, Fiji. Australasian Institute of

Mining and Metallurgy, Proceedings 204:135-160. Ibbotson, P. 1967. Petrology of the Tertiary Caldera, Tavua Goldfield. Fiji Geological

Survey Memoir 3. Setterfield, T.N; Eaton, P.C; Rose, W.J and. Sparks, R.S.J. 1991: The Tavua caldera,

Fiji: a complex shoshonitic caldera formed by concurrent faulting and downsagging. Journal of the Geological Society, London, Vol 148, 1991, pp. 115-127.

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APPENDIX 1 : MRD-SOPAC Visual Core Description

Survey Area : Nasivi Delta, Tavua Site No. : TV 99/1 Position : 170 26’ 6.8” Lat 1770 51’ 45.6” Long Drill Depth : 48 m

Date : 24/11/99

Start/Fin Times : 12:15 – 18:15 General Comments :

Depth (m) Colour/grain size Section Description

0-1 Dark loamy soil Top soil, dark loamy soil with some sand.

1-2 Dark loamy soil Dark loamy soil with plant fragments (roots)

2-3 Black mud and fine sand

Black mud with fine sand and shells. Shells up to 2 cm.

3-4 Black fine sand Black sand with some sub-angular pebbles (up to 2 mm).

4-5 Black fine sand Black sand with sub-angular pebbles (up to 2 mm) and shell fragments (1.5 cm).

5-6 Black fine sand Fine sand with some soft clay

6-7 Black sand, fine Fine sand with soft to stiff, plastic clay. (2 Casings down)

7-8 Greenish clay Greenish soft to stiff plastic clay with some fine sand.

8-9 Same as above.

9-10 Same as above.

10-11 Same as above.



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14-15 Black sand, fine to medium

Black sand with some yellowish brown soft to stiff plastic clay.



Black sand with some yellowish brown soft to stiff plastic clay and some pebbles (up to 4 mm).


Black sand with some soft clay. (2 casing down)


19-20 Black sand with some pebbles

Fine to medium black sand with some angular pebbles (up to 3 mm).


21-22 Greenish clay Greenish soft to stiff plastic clay with some fine to medium sand and some sub-angular pebbles (3 mm).








Fine to medium sand with some angular pebbles (3 mm).


30-31 Black sand, fine Fine grain black sand. No pebbles.

31-32 Black sand, fine Fine black sand with very angular pebbles (3 mm).

32-33 Same as above but pebbles are sub-rounded to rounded.


34-35 Black sand, fine

35-36 Black sand, fine Black fine sand with some reddish brown soft to stiff plastic clay mixture.

36-37 Reddish brown clay

Soft to stiff plastic clay.

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Clay/fine sand mixture


Clay/fine sand mixture with some angular to sub-angular pebbles.


Clay/fine sand mixture with some angular to sub-angular pebbles.



Fine to medium sand with angular to sub-angular pebbles (2 mm)






47-48 Same as above. (END OF HOLE).

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MRD-SOPAC Visual Core Description

Survey Area : Nasivi Delta, Tavua Site No. : TV 99/2 Position : 170 26’ 8.0” Lat 1770 51’ 51.9” Long Drill Depth : 48 m Date : 23/11/99

Start/Fin Times : 0800 - 1815 General Comments :


0-1 Black loamy soil Top soil/mud with some sand.

1-2 Same as above.

2-3 Brownish clay Clay and fine sand mixture


Fine to medium black sand with shell fragments (1 cm).

4-5 Black, fine Black mud and fine sand mixture. No shell fragments.

5-6 Brownish Clay Soft clay with some fine sand.

6-7 Greenish Greenish soft clay. No sand. (2 casings down)

7-8 Same as above.

8-9 Yellowish brown clay

Yellowish brown stiff plastic clay with some fine sand.

9-10 Greenish brown clay

Greenish brown soft plastic clay with some fine sand.


Greenish brown soft plastic clay. No sand present.



Greenish brown soft to stiff plastic clay with sub-rounded to rounded pebbles (2 mm) and little sand. (2 casings down).

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13-14 Black sand, fine Fine sand with yellowish brown soft plastic clay.




17-18 Black sand, fine Fine sand with yellowish brown soft plastic clay. (2 casing down)


Very soft yellowish brown plastic clay with little fine sand.




22-23 Black sand, fine Fine sand with some yellowish brown soft clay.





Sand with some soft yellowish brown clay.



29-30 Black sand, fine Fine sand with some stiff, plastic greenish clay. (2 casings down).


Soft to stiff plastic clay with some fine sand.


Soft to stiff plastic clay. No sand present.


Soft to stiff plastic clay with some fine sand.




35-36

Same as above. (2 casings down). 36-37 Same as above.


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Sand with some reddish brown soft clay.




Sand with sub-angular pebbles (2 mm).




44-45 Black sand, fine Sand with reddish brown soft clay.



47-48 Same as above. (END OF HOLE).

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Survey Area : Nasivi Delta, Tavua Site No. : TV 99/3 Position : 170 26’ 8.9” Lat 1770 51’ 54.86” Long Drill Depth : 51 m Date : 19/11/99 Start/Fin Times : 0920– 1823 General Comments :

Depth (m)

Colour/grain size Section Description

0-1 Black mud Top soil/mud layer.

1-2 Black to brown mud Mud with some plant roots and fine sand

2-3 Black to brown mud Mud with fine sand and angular pebbles (2 mm).

3-4 Black sand, fine Sand with angular to sub-rounded pebbles (up to 8 mm) of various types.

4-5 Same as above. (Drilling stopped – lack of water)

5-6 Black mud Mud with a little sand.

6-7 Green clay Chloritised soft clay layer with very little sand.

7-8 Yellowish brown clay Soft clay with very little sand.

8-9 Yellowish brown clay Stiff, plastic clay. No sand present.

9-10 Same as above.


11-12 Same as above. (DRILLING STOPPED – NO WATER). 12-13 Greenish brown clay Stiff plastic clay. No sand.


14-15 Same as above. (Casing pulled up – cannot penetrate clay layer).

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17-18 Greenish brown clay Stiff plastic clay with some rounded to sub-rounded pebbles (2 mm).

18-19 Greenish brown clay Stiff plastic clay with some angular to sub-angular pebbles (3mm) with some medium sand.



21-22 Same as above. (POOR RECOVERY).

22-23 Greenish/reddish brown clay

Stiff plastic clay. No sand. (POOR RECOVERY).





27-28 Reddish brown clay/sand, coarse.

Stiff plastic clay with coarse sand

28-29 Reddish brown clay/sand, coarse.

Stiff plastic clay with coarse sand.


30-31 Black sand, fine to coarse Sand with some clay.








38-39 Same as above, but an increase in the clay content.

39-40 Black sand, fine to coarse Sand with some soft clay.

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44-45 Black sand, fine to coarse Sand with some stiff plastic clay.

45-46 Reddish brown clay Stiff plastic clay with coarse sand and some angular to sub-angular pebbles (3 mm).




49-50 50-51

Reddish brown clay Same as above. Stiff plastic clay with some sand. (END OF HOLE).

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Start/Fin Times : General Comments :


0-1 Black top soil

1-2 Black mud Cohesive mud.

2-3 Black sand medium to coarse

Sand with some cohesive black mud and sub-rounded pebbles (12 mm).

3-4 Same as above.

4-5 Same as above,

5-6 Sand/mud/clay Mixture of sand, mud and clay. (2 casing down).


Stiff plastic clay.

7-8 Same as above.

8-9 Same as above.

9-10 Same as above.



Soft plastic clay. (2 casings down).

12-13 Greenish yellowish brown clay

Stiff plastic clay.


Soft plastic clay with angular pebbles (10 mm) and fine to medium sand. Clay content more than sand.

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14-15 Greenish brown clay/sand, fine to medium

Soft plastic clay and sand mixture with smaller sized pebbles.


Sand with some clay and pebbles (3 mm).

16-17 Black sand, fine to coarse

Sand with angular to sub-rounded pebbles (5 mm). (Gold grain barely visible to eye in sample panned on site).


Sand with angular to sub-rounded pebbles (5 mm). (Gold grain barely visible to eye in sample panned on site) (2 casings down).

18-19 Pebbles Pebble bed? Sub-angular to sub-rounded (2 cm).





23-24 Pebbles Sub-angular to sub-rounded pebbles with some soft plastic clay. (2 casings down).


Soft plastic clay and some sub-rounded pebbles (3 mm).

25-26 Brownish clay Soft to stiff plastic clay.



28-29 Brownish clay Soft clay.

29-30 Same as above. (2 casings down).


31-32 Brownish clay Soft clay with little fine sand.

32-33 Black fine sand/pebbles layer

Sub-angular to sub-rounded pebbles of various sizes.

33-34 Pebbles Sub-angular to sub-rounded pebbles of various sizes.




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38-39 Greenish to brownish clay


39-40 Greenish clay Soft to stiff plastic clay.


41-42 Greenish clay Soft to stiff plastic clay with some sub-angular pebbles.


Soft to stiff plastic clay. No pebbles.




Soft to stiff plastic clay with some fine to medium sand.




49-50 50-51

Same as above. Same as above. (END Of HOLE).

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0-1 Black top soil

1-2 Same as above

2-3 Black top soil Black soil with some fine black sand.


Sand with some angular pebbles (5 mm).

4-5 Black sand, coarse Sand with some mud and sub-rounded pebbles (2 cm).


Soft plastic clay with some sand and sub-angular to sub-rounded pebbles (5 mm). (2 casings down).


Soft plastic clay with some sand and some shells (12 mm).


Soft plastic clay.

8-9 Brownish clay Soft plastic clay.

9-10 Same as above.



Stiff plastic clay with very little black fine sand. (2 casings down).




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Soft to stiff plastic clay with some black fine sand.


Sand with some stiff greenish to brownish plastic clay.

16-17 Black sand/clay mixture

Fine to medium sand with some greenish to brownish stiff plastic clay.

17-18 Greenish clay Soft plastic clay with some black fine sand. (2 casings down).

18-19 Brownish clay Soft to stiff plastic clay with some black fine sand and sub-angular pebbles (2 mm).



21-22 Brownish clay Soft to stiff plastic clay with some coarse sand.















Sand with some sub-angular pebbles (2 mm) and some clay.


Soft clay with some black fine to medium sand.



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Soft clay. (POOR RECOVERY).



Clay with little black fine sand. POOR RECOVERY).




47-48 Same as above. (POOR RECOVERY). (END OF HOLE).

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Survey Area : Nasivi Delta, Tavua Site No. : TV 99/6 Position : 170 25’ 53.4” Lat 1770 52’ 2.1” Long Drill Depth : 30 m Date : 02/12/99 – 04/12/99



0-1 Brownish black top soil

Soil with some organic material (plant roots).

1-2 Brown clay/fine black sand

Stiff plastic clay with some sand and a few sub-angular pebbles (2 cm).

2-3 Black sand, medium to coarse

Sand with sub-angular to sub-rounded pebbles (3 mm).

3-4 Same as above.

4-5 Black sand, medium to coarse

Sand with sub-angular to sub-rounded pebbles (3 mm) and some shell fragments.


6-7 Black sand, medium to coarse/clay

Sand with greenish to brownish soft plastic clay and some sub-angular to sub-rounded pebbles (2 mm). (Water pump problem – poor recovery of samples up to 15-16 m depth).



9-10 Same as above.


11-12 Brownish clay Soft to stiff plastic clay. (2 casings down).


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14-15 Brownish clay Soft clay with some sub-angular pebbles (2 mm).

15-16 Brownish clay Soft clay. (Stopped drilling).

16-17 Same as above. (resumed drilling 04/12/99).

17-18 Brown clay Soft clay. (2 casings down).

18-19 Brown clay Soft clay with very little medium grained sand.





Soft clay with very little fine grained sand.



Sand with some soft clay.




28-29 Black sand, fine to medium.

29-30 Black sand, fine Sand with some soft brownish clay. (End of hole).

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0-1 Brown loamy soil Top soil, brown loamy soil mixed with sand, non plastic with little vegetation. (use of drilling mud)

1-2 Same as for above

2-3 Rounded basaltic Pebbles up to 1 cm in diameter

Mixture of soil and sand with basaltic pebbles up to 1 cm in diameter. (casing used for drill hole)



5-6 Dark, fine silt Fine, dark silty material with shell fragments

6-7 Dark, fine silt Dark, fine silty material with abundant angular shell fragments. Fragments up to 1 cm in diameter. (very poor recovery)

7-8 Fine dark/greenish Silt with coarse pebbles

Fine dark to green silt with some shell fragments and coarse pebbles. (very slow drilling and drilling stopped due to lack of water).

8-9 Same as above.

9-10 Greenish yellow clay

Clay material, plastic with mixtute of some sand and sub-rounded basaltic pebbles up to 2 cm in diameter, no shell fragments.


Plastic clay material with less sand. No pebbles present.


Clay material, plastic with mixtute of some sand and sub-rounded basaltic pebbles up to 2 cm in diameter, no shell fragments.

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12-13 Dark sand up to 3 mm

Very coarse basaltic sand and clay mixture, sand up to 3 mm, very angular

13-14 Dark sand Very angular coarse sand and some (little) clay. (Angular sand could be result of rotary drill drilling through gravel bed)


15-16 Greenish Yellow clay

Clayey material with some coarse angular sand


Clayey material with very little sand present.


Very plastic clay. No sand present.




21-22 Dark sand, fine to coarse

Fine to coarse grained sand with very little clay. Sand particles very angular.





26-27 Brownish clay Brownish clayey material with little fine grained sand.

27-28 Same as above

28-29 Brownish clay with slightly more fine sand

29-30 Same as above

30-31 Dark sand, fine to medium

Dark fine to medium sand with some clay

31-32 Same as above

32-33 Same as above

33-34 Same as above

34-35 Same as above

35-36 Brownish clay Brownish clay with some fine sand

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36-37 Same as above

37-38 Same as above

38-39 Same as above

39-40 Same as above

40-41 Same as above

41-42 Same as above

42-43 Dark sand, fine to medium

Sand, fine to medium with little clay

43-44 Same as above

44-45 Same as above. (poor recovery)

45-46 Same as above

46-47 Brownish clay Clay with some sand and pebbles. Pebbles approximately 3 mm, sub-rounded.

47-48 Dark, fine to medium

Dark sand, fine to medium grain. (END OF HOLE)

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0-1 Brownish black top soil

1-2 Brownish black soil Soil with some medium grained sand and sub-rounded pebbles (5 mm).


Sand with sub-rounded pebbles (1 cm) and shell fragments.

3-4 Same as above.

4-5 Same as above.



Sand with some soft whitish clay. (Poor recovery).



Sand with some soft whitish clay.

9-10 Same as above.



Sand with soft whitish clay and some subronded pebbles (3 mm). (2 casings down).

12-13 Brownish clay Soft to stiff plastic clay with very little fine sand.


Sand with very little clay and some pebbles (3 mm).

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Sand with some sub-rounded pebbles (3 mm) and little brown clay.

18-19 Sand, coarse Pebbly sand (3 mm).


20-21 Sand, coarse Pebbly sand (3 mm) with some soft brown clay.


22-23 Brownish clay Soft clay with some coarse grained sand.

23-24 Brownish clay Soft clay with little sand. (End of hole).

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APPENDIX 2. Daily Log Narratives

Date Comments

15/11/99 Depart for Tavua and arrive at camp site (PWD Barracks) at 1730.

16/11/99 Move drill truck to first drill site and prepare site for drilling. Locate and peg other drill hole sites. Dig sump and locate water source. Day ended at 2000.

17/11/99 Start of day at 0700. Moved to drill site and prepared for drilling. Commenced drilling of TV99/8 at 0950. Drilling stopped at 1920 at a depth of 48 m. 3 casings used. Day ended at 2100 with all drilling rods and casings pulled out, ready for next drill site. Drilling was hampered by adverse weather conditions.

18/11/99 Continuous rain has caused the mud to be soft resulting in drill rig being bogged down. After a couple of hours of letting the mud dry it was decided to try moving the drill rig to site TV99/3. This was achieved after much difficulty. The afternoon consisted of packing and moving to site TV99/3. Site was prepared for drilling. Day ended at 1900.

19/11/99 Drilling was smooth and a depth of 51 m was reached. Drill rods pulled up but casings left in place due to darkness. Day ended at 2000.

20-21/11/99 Due to communication breakdown there was no work in the weekend.

22/11/99 Drill crew pulled up the six casings left in drill hole TV99/3 and prepared to move to drill hole TV99/2. Day ended at 1900.

23/11/99 Day started at 0700 and ready for drilling. Logging results of hole wasn’t exciting. Panning showed several pieces of “gold” coloured particles, which were pyrite. Depth of hole was 48 m. Prepared the drill site TV99/1 by digging of sump. Drill rods pulled out but casings left in place due to darkness fast approaching. Day ended at 1930.

24/11/99 Day started at 0700. Casings pulled out and moved to site TV99/1. Started drilling at at1215. Drilling went smoothly and a depth of 48 m was reached. Day ended at 1930.

25/11/99 Mobilisation to drillhole TV99/4. Mechanic fixed crane, which made lifting of rods and casings easier. Drilling commenced at 1435. At 1830 problems encountered with drilling process, which was due to clutch problems of the drill rig. Drilling stopped at 1900 at a depth of 27 m. Day ended at 1930.

26/11/99 Drilling supervisor contacted office for either drill rig to be brought from Sigatoka or repairs be made to drill rig. SOPAC team using a mechanical auger augered down to six metres. Drilling of TV99/4 continued until a depth of 51 m was reached. Mechanic arrived at 1500 to fix clutch plate and the gearbox had to be opened. Mechanic returned to Suva acquire parts for repairs. Day ended at 1930.

27/11/99 No work done. Heavy rain has resulted in the road being under water. Inspection of the bridge at the Tavualevu end of the survey area

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showned that the bridge is on the verge of collapse, hence alternate route to survey area had to be used.

28/11/99 Mechanic arrived at 1130 and fixed rig. Mechanic departed at 1630.

29/11/99 Visited site at 0730 which was still under water. Rig unable to start due to flat batteries. Batteries taken to be PWD to be charged.

30/11/99 A grader from PWD was brought in to pull the drill rig and truck from site TV99/4. Landowner problem delayed start of drilling TV99/5. Drilling finally started at 1115. Drilling progressed well and stopped at 48 m. Sample recovery for the last 10 m was poor and the sample being of the same material.

01/12/99 Drill rig developed starting problem. Having checked the starter it was found that the solenoid was burnt out. Cost of replacement for a new solenoid was too expensive, hence a call made to MRD for a replacement. Work done was shifting of the tent and digging of the sump for drillhole TV99/6.

02/12/99 Waiting for mechanic to arrive from Suva to fix starter. Rig fixed by 1430. Casings and rods pulled up and rig moved to site TV 99/6. Started drilling at 1700 and ended at 2000 when 6 m was reached.

03/12/99 Resumed drilling of TV99/6 at 1000. Sample recovery poor due to water pump problems. New belts bought in Lautoka but did not function to full capacity. Drilling stopped at 16 m at 1900.

04/12/99 Day started at 0630. Three new belts bought in Ba. Drilling resumed at 1000 and ended at 1330 at a depth of 30 m. Drill rig moved to TV99/9, a non-target site and drilling commenced 20 m NE of original site. Drilling started at 1600 and ended at 1930 when lighting was poor. Depth reached was 24 m.

05/12/99 Mobilisation for return to office

06/12/99 Return to office.

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APPENDIX 3

Drill Logs

detrital gold assessment: drilling, nasivi delta, tavua, fiji

Documents