Siren Gold Limited (ASX: SNG) has provided an update on exploration activities at its Alexander River and Big River projects in New Zealand.
Highlights
• The results to date indicate that the A2 shoot is plunging around 55o to the NNE, similar to Shoots 1, 2 and 3. The A2 shoot can now be traced from outcrop to 300m down plunge or 250m below surface.
• Mapping and soil geochemistry has confirmed that the Sunderland Anticline that hosts the Big River mine extends for at least five km south, where it is cut off by younger granite intrusion, and one km to the north, where the mineralisation is overlain by coal measures.
• Drilling at Alexander River has confirmed the Bull West Shoot that now extends over 200m and is open up and down plunge.
Alexander River
The Alexander mineralisation outcrops for over 1.2kms and is comprised of high-grade quartz reefs and disseminated mineralisation. Surface trenching and channel sampling shows that the mineralisation ranges from 2-15m thick, with an average thickness and grade of 4m @ 8g/t Au. Surface sampling identified four mineralised shoots, named Bull, McVicar, Bruno and Loftus- McKay.
Only the McVicar East Shoot was mined to any extent, with the shallow plunging shoot mined to 250m below surface, extracting 41koz at an average recovered grade of 26g/t Au before the mine closed in 1942.
The Alexander River mineralised zone can be divided into two structural domains. The Bull-McVicar-Bruno reef track is ENE striking, steeply SE dipping, while the Loftus-McKay reef track extends from Bruno into Mullocky Creek and is NNE- striking and dips 50o to the NW.
The mineralised shoots comprise both quartz reef and disseminated acicular arsenopyrite mineralisation, with the gold grades in the disseminated mineralisation often higher than in the quartz. Historical reports, and limited drilling to date, indicate that the historic miners targeted the quartz reefs and left the disseminated mineralisation behind, as the gold was difficult to recover.
The McVicar East Shoot was mined to Level 5 and a west dipping shoot was intersected between Levels 5 and 6 of the McVicar mine. Mining stopped on Level 6 in 1942, with only minor stoping of the McVicar West Shoot.
The McVicar West Shoot has now been intersected in a number of drillholes an additional 650m down plunge below the McVicar mine where the shoot is offset by an inferred fault. Similarly, the Bull West and Loftus-McKay Shoots have also been offset by the fault.
Recent Exploration
Recent exploration has been focused on finding the Loftus McKay and McVicar West shoots on the NE side of the fault and targeting the Bull West Shoot that was intersected by AX68a. Drillholes AX45 (2m @ 26.8g/t Au), AX47 (5m @ 9.1 g/t Au), AX50 (21.8m @ 2.3g/t Au including 7.8m @ 4.3g/t Au) and AX89 (2.3m @ 10.2g/t Au) all intersected high-grade mineralisation on the SE side of the fault.
Drillhole intersections on the NE side of the fault have intersected the reef track but have not intersected the shoots at this stage. The displacement across the fault is unclear but there appears to be a normal displacement of around 50m. To get a better indication of the fault displacement a drone based magnetic survey is being completed. This will better define fault offsets of the dolerite dikes that have been traced with ground-based magnetics. The dolerite dikes postdate the mineralisation and any offsets of the dikes will also offset the mineralisation.
Drillhole AX68a (11.1m @ 1.7g/t Au including 5m @ 2.2g/t Au) intersected the Bull West Shoot. The Bull West Shoot has also been intersected by AX102 (3.8m @ 2.0g/t Au) and AX103 (11m @ 1.2g/t Au). Results for AX104, AX105 and AX106 are awaited.
Drilling has been paused at Alexander River until the results of the drone survey are available. An updated MRE will be completed in the coming months.
Big River
The Big River project (comprised of Exploration Permit 60448) is located ~15 km SE of Reefton. The project overlays the areas of the historic Big River Mine which produced ~136,000 oz of gold at an average recovered grade of 34g/t between 1880 and 1942.
The historic underground mine workings have been modelled in 3D and this, coupled with historic mine reports, shows that four main ore shoots were mined around the Sunderland anticline. Shoot 1 was mined to Level 4, Shoot 2 to Level 6, Shoot 3 to Level 12 and Shoot 4 to Level 7, when the mine closed in 1942. Two new potential shoots, the A2 and Prima Donna, are located east and west of the Big River mine. The A2 shoot, Big River Mine and Prima Donna shoot combined cover a strike length of around 500m, which is overlaid by anomalous gold and arsenic soil geochemistry.
Diamond drilling commenced at the Big River project in 2011 when OceanaGold Limited (OGL) drilled 26 holes for a total of 5,032.6m. Siren commenced drilling in October 2020 and initially drilled 16 holes for a total of 2,743m.
Drilling was focused on Shoots 4 and A2. Previous drillhole results that intersected Shoot 4 include BR03 (2m @ 12.1g/t Au), BR04 (4m @ 4.4g/t Au from 128m and 6.6m @ 21.4g/t Au from 136m), BR09 (3m @ 18.5g/t Au from 147m and 4m @ 7.8g/t Au from 158m), BR12 (3m @ 5.4g/t Au from 170m and 3m @ 2.0g/t Au from 205m), BR27 (6m @ 5.1g/t Au), BR34 (5.9m @ 4.1g/t Au) and BR35 (6.3m @ 3.4g/t Au from 374.8m).
The A2 shoot is in a second anticline 200m to the west of the Sunderland anticline that hosts the Big River mine. Mapping and channel sampling identified outcropping quartz reef up to 1m thick surrounded by sulphide-rich sediments containing lenses of massive sulphide in the footwall. Channel sampling indicates that the quartz reef is relatively low grade, but the footwall mineralisation assayed up to 11g/t Au. Seven shallow diamond holes drilled into the A2 Shoot tested 100m along strike to a depth of around 25-50m. Drillhole BR20 intersected 5.0m @ 4.2g/t Au from 24m and BR31 intersected 3.4m @ 2.5g/t Au from 41m. BR22 – BR24 were drilled on a second structure 30m to the west. These holes intersected a 10m wide zone with lower grade gold mineralisation but with the same high arsenic and sulphur mineralisation. BRDDH023 has very high sulphur, averaging 10.9% over 8m, with a high of 36% over 1m. These results are encouraging and indicate a strongly mineralised system near surface.
Recent Exploration
Siren recommenced drilling in March 2022 with nine holes for 2,887m completed to date. Eight holes have been drilled in the A2 Shoot and one hole in Shoot 4, with BR45 in progress.
The deeper drilling in the A2 Shoot indicates that the shoot has a slightly shallower plunge than previously interpreted and that drillholes BR40 and BR41 intersected the footwall. Drillholes BR37 (5.2m @ 6.3g/t Au from 213m), BR41 (6m @ 1.5g/t Au from 252m) and BR39 (10m @ 1.2g/t Au from 271m, including 3m @ 2.5g/t Au) have extended the A2 Shoot to around 250m below the surface.
BR44 was drilled into Shoot 4, 100m below BR35 (6.4m @ 3.7g/t Au from 375m). This hole intersected the mineralised zone at 425m but then intersected a 16m thick dolerite dyke that cut-off the mineralisation (Figure 4). BR45 is now being drilled 100m above BR34 (5.9m @ 4.1g/t Au from 361m) to see if the mineralisation extends to the SE of the Level 7, similar to the area below Level 3.
Soil geochemistry has now been completed for over 6kms from Big River North to around 2kms south of St George. The arsenic soil geochemistry shows large anomalies at Big River mine and a three km long anomaly from Golden Hill to south of St George.
The results clearly show that the arsenic anomaly continues strongly to the south until it is cut off by younger granite and extends into a broad zone south of St George into an area that has not been historically mined. Anomalous arsenic also extends for 1.5kms NE of Big River to the contact with overlying Eocene coal measures. The gold soil geochemistry shows a similar trend, with the results for the two southernmost lines still awaited.
For further information please visit: https://www.sirengold.com.au
