782f46d0-7108-4b92-a6f1-3f6a52654eaa.pdf
ASX/Media Announcement
26 April 2016
VHMS TARGET IDENTIFIED AT DEPTH AT RED BORE
Thundelarra is pleased to announce that it has identified an exciting VHMS target at depth at Red Bore. The latest Diamond drilling confirms the geological setting for VHMS ("volcanic-hosted massive sulphide") mineralisation. The rock types, geochemistry, structures and the relationships between each of these factors has combined with re-interpretation of earlier gravity data to identify this target.
Highlights:
-
Re-processed gravity data has revealed a target at 500m+ below surface, centred about 170m NW of Gossan. Possible interpretations include:
-
a lens of VHMS (massive sulphides);
-
a major feeder for the Gossan mineralisation;
-
a fold nose of mineralised volcaniclastics; or
-
a plug of mineralised mafic intrusion (basal gabbro?).
-
Detailed petrography confirms the setting has potential for VHMS
-
Further similarities to the Monty VHMS deposit confirmed: host sequence at Red Bore is bounded above and below by dolerite sills, as at Monty.
-
Approval to test this target in the June Quarter is currently underway.
Gold:
-
PoWs approved for Mooloogool and Garden Gully prospects
-
HPAs (Heritage Agreements) signed by Traditional Owners
-
Heritage clearance discussions underway to gain access to explore
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Drilling to commence upon completion of statutory processes
CEO Tony Lofthouse expressed immense satisfaction with progress at Red Bore. Technical rigour has been the key to exploration since restarting in April 2014, continually improving the geological model and helping direct exploration towards what we believe will be a discovery.
"Doolgunna is the place to be for VHMS exploration at the moment. Discoveries like Monty assist all the local explorers and the similarities we are seeing at Red Bore to both De Grussa and Monty promise much for our future exploration. The deep gravity target just north-west of Gossan, in the correct suite of rocks bounded by dolerite sills above and below, like at Monty, has us all very excited about the next stage of drilling, which we are planning now for the June Quarter."
Thundelarra Limited | ABN: 74 950 465 654 | Level 1, 186 Hampden Rd, Nedlands WA 6009 | PO Box 7363, Cloisters Square, WA, 6850
www.thundelarra.com.au | [email protected] | Tel: +61 8 9389 6927 | Fax: +61 8 9389 5593
The Red Bore project, 90%-owned by Thundelarra, is a two square kilometre granted Mining Licence (M52/597) located in Western Australia's Doolgunna region (Figure1).
Figure 1. Location map of Red Bore and Curara Well Projects showing proximity to DeGrussa copper-gold mine (Sandfire Resources NL). Scale: grid spacing is 30 km.
Hole
|
East
|
North
|
RL
|
Depth
|
Dip
|
Azimuth
|
Prospect
|
Licence
|
TRBD010
|
735074
|
7172384
|
575m
|
217m
|
-65o
|
189o
|
Impaler
|
M52/597
|
TRBD011
|
735036
|
7172342
|
575m
|
195m
|
-60o
|
0o
|
Impaler
|
M52/597
|
TRBD012
|
735920
|
7172537
|
580m
|
292m
|
-83o
|
177o
|
Gossan
|
M52/597
|
TRBC107
|
735067
|
7172249
|
575m
|
211m
|
-60o
|
010o
|
Impaler
|
M52/597
|
TRBC108
|
735129
|
7172290
|
576m
|
168m
|
-60o
|
330o
|
Impaler
|
M52/597
|
TRBC109
|
735057
|
7172434
|
574m
|
157m
|
-60o
|
347o
|
Impaler
|
M52/597
|
TRBC110
|
736088
|
7172315
|
574m
|
115m
|
-60o
|
338o
|
Unnamed
|
M52/597
|
TRBC111
|
736407
|
7172585
|
574m
|
163m
|
-60o
|
358o
|
Jaspilite
|
M52/597
|
TRBD013
|
735025
|
7172259
|
575m
|
506.6m
|
-75o
|
021o
|
Impaler
|
M52/597
|
TRBD014
|
735830
|
7172443
|
580m
|
490.7m
|
-75o
|
049o
|
Gossan
|
M52/597
|
Table 1. Details of the holes drilled in this programme at Red Bore. "TRBD" denotes Diamond holes; "TRBC" are Reverse Circulation holes. All locations on Australian Geodetic Grid GDA94-50. The azimuth column records the magnetic azimuth of the drilling direction.
The programme had four main objectives:
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To improve the understanding, and to test for extensions, of the Impaler mineralisation by Diamond drilling. It was hoped that core samples would give clearer geological information from the zones where earlier reverse circulation drilling had encountered broken ground;
-
To improve the understanding of the mineralisation at depth at Gossan;
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To re-visit the Jaspilite target to the east of Gossan that was previously tested by RC;
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To re-visit a target south-east of Gossan, located close to the southern tenement boundary.
This announcement provides previously unreported results from TRBC107-111 and TRBD013-014.
The presence of peperitic (Figure 2) and other textures in the core in these holes at both Impaler and Gossan provided further geological evidence that the package of Interfingered volcaniclastic sediments, basalts, plus the dolerites, does indeed represent a geological setting with the potential to host VHMS mineralisation.
Figure 2. Peperitic texture: ~400m downhole in TRBDD013 at Impaler. Scale: core is 5cm wide.
This provided the rationale for undertaking laboratory multi-element assays to deliver greater accuracy than the readings obtained to date from hand-held XRF Analyser. These anomalous pathfinder elements (including Zn, Pb, Mo, As, Bi, Sn, Se, Ag, Au) also validate the potential for VHMS settings (refer Table 2; Appendix 1; and ASX announcement dated 29 March 2016).
VHMS Pathfinders
|
Element
|
Zinc
|
Lead
|
Moly
|
Arsenic
|
Bismuth
|
Gold
|
Unit
|
ppm
|
ppm
|
ppm
|
ppm
|
ppm
|
ppb
|
Background
|
100
|
35
|
0.7
|
27
|
0.4
|
80
|
Anomalous cut-off (3 x background)
|
300
|
100
|
2.0
|
75
|
1.0
|
250
|
Hole No
|
From
|
To
|
Interval
|
Zn
|
Pb
|
Mo
|
As
|
Bi
|
Au
|
TRBC107
|
124
|
133
|
9m
|
194
|
6.0
|
|
TRBC108
|
84
|
92
|
8m
|
273
|
158
|
4.1
|
|
TRBC110
|
6
|
18
|
12m
|
5.4
|
0.8
|
|
TRBD010
|
20.7
|
51
|
29.3m
|
591
|
262
|
126
|
2.5
|
|
TRBD011
|
29
|
33
|
4m
|
559
|
858
|
140
|
7.3
|
|
TRBD012
|
26
|
46
|
20m
|
472
|
24.1
|
1.4
|
538
|
66
|
75
|
9m
|
279
|
10.8
|
559
|
|
TRBD013
|
279
|
291
|
12m
|
1.4
|
394
|
397
|
3m
|
296
|
1.0
|
|
Table 2. Significant drill intercepts of anomalous VHMS pathfinder elements. See Appendix 1 for all assays.
This programme intersected the first primary copper mineralisation, displaying representative VHMS-style characteristics, seen at Impaler (Figures 2, 3, 4). The copper-gold-silver mineralisation previously reported there has been secondary / supergene in nature.
Figure 3. 395m in TRBDD013 at Impaler. Figure 4. 399m in TRBDD013 at Impaler. Primary sulphide fiamme in volcaniclastics. Primary sulphide, possibly remobilised.
The structural interpretation around Impaler (Figure 5), together with the geological information from hole TRBDD013, indicates that the package of rocks at depth is in the correct setting for the VHMS mineralisation sought. The volcaniclastics displaying peperitic textures, together with the footwall dolerite and the syngenetic sulphides observed, all augur well for the next stages of exploration. Figure 6 presents a cross-section summarising the current interpretation.
Figure 5. Impaler ground magnetics anomalies with drill collars, hole traces and interpreted structures.
The broken ground and faulting encountered in the first two Diamond holes of the programme (TRBD011 and 012) at Impaler meant that these holes did not deliver all the data we had sought.
TRBD010, 011 at Impaler and TRBD012 at Gossan were reported and discussed in the previous announcement dated 29 March 2016. A further five RC holes and two Diamond holes were drilled in the second part of the programme (Figures 5, 7). The RC holes principally targeted further shallow magnetic targets delineated in the detailed ground magnetic survey carried out in 2015.