NickelX Limited (ASX:NKL) has completed an initial review of the gold prospectivity at the Biranup Project in Western Australia where previous and current work has identified Black Dragon as a high priority gold target, and where exploration works have now been prioritised, planned for the September Quarter 2021.
Managing Director, Matt Gauci, saidthe Black Dragon gold target is located ~30km NE of the Tier 1 Tropicana gold operations and ~35km SW of the emerging Hercules gold discovery,within a ~10km X 3km, NE-SW-striking zone of significant surface gold anomalism that is spatially coincident with the Black Dragon shear zone, as well as a >250km- structural feature in gravity data that also passes through Tropicana.
Black Dragon represents a compelling gold exploration target with significant historic results reported by previous explorers and an initial review from current work, demonstrating a high priority gold target which is located along strike from the Tier 1 Tropicana gold operations,” MrGauci said.
“Now having prioritised the targets the Company is organising an IP Survey and RC and/or DD program for the September Quarter 2021, to better understand Black Dragon, while we are completing our EM surveys at Fire Dragon and organising a EIS funded DD program, seeking Nickel-Copper deposits as our primary target at Biranup.”
The Black Dragon gold target at the Company’s Biranup Project is in the northern Albany-Fraser Orogen (AFO), ca. 30 km NE of the Tier 1 Tropicana gold operations and 35km SW of the emerging Hercules gold discovery, all of which lie along the interpreted Northern AFO Gold Corridor.
The AFO, a ca. 1,200 km-long, arcuate, Neoarchean to Mesoproterozoic fold belt that developed along the southern and south-eastern margins of the Archean Yilgarn Craton and upon a Yilgarn-like Archean basement, is divided into a number of fault-bound tectonostratigraphic zones, mainly comprising para- and orthogneisses that have been metamorphosed at amphibolite to granulite facies conditions and intruded by late-tectonic granitoid plutons.
The Black Dragon prospect is situated along the Black Dragon shear zone, a laterally extensive (>100km- long), NNE-SSW- to NE-SW-striking and ESE-dipping thrust separating the 2,720 to 1,700 Ma Tropicana Zone to the S and the 1,815 to 1,625 Ma Biranup Zone to the N. The Tropicana Zone is represented by the ca. 2,640 Ma Tropicana Gneiss and several intrusive units. The Biranup Zone is mainly comprised of the 1,815 to 1,800 Ma Black Dragon Gneiss and an unnamed metagranitic unit.
The outcropping quartz (±hematite, ±breccia) veins at Black Dragon were first recognised by AngloGold Ashanti Limited (AGA) during the company’s 2007-08 field season. Rock chip sampling at Black Dragon by AGA returned significant gold assay values up to 573 g/t Au. These results were followed-up with an aircore (AC) drilling campaign, undertaken on a 200m×400m grid. The best result from this drilling was 1.00m @ 13.27g/t Au from surface in hole BDA189.
Additional AC drilling during the 2008-09 field season defined a coherent, low-level gold anomaly along strike to the NE and up to 2km from the outcropping quartz veins (WAMEX Reports a79742, a84617). Following the high-grade intercept in hole BDA189, two phases of reverse circulation (RC) drilling were completed during AGA’s 2008-09 field season with 22 holes drilled for a total of 3,001m. Of these holes, 12 were completed in the Black Dragon prospect area.
Whilst the drilling intercepted a sequence of sericite- altered granite with disseminated pyrite (i.e., a typical gold-related hydrothermal alteration assemblage), quartz (±hematite, ±breccia) veins as exposed at surface were not intersected. Nevertheless, the RC drilling returned several narrow, gold anomalous intercepts with a best result of 1.00m @ 3.96g/t Au from 84.00m in hole BDRC008. In 2014, the tenement containing the Black Dragon prospect was relinquished.
Ventnor Resources Limited (now VRX Silica Limited) explored the Black Dragon gold prospect in 2015 and 2017. Initial work by VRX involved geological mapping and rock chip sampling. Ten of the 32 rock chip samples collected at Black Dragon returned gold assay values >1.00g/t Au, with a peak assay of 626.00g/t Au, 154.00 g/t Ag and 651.00 ppm Te (sample BD103) returned from this program and indicating the presence of a gold-silver-tellurium mineralised system.
Later in 2015, VRX commenced a drilling programme at Black Dragon, including 33 RC holes for 2,492 m. The holes were drilled in multiple orientations as to gain a better understanding of the orientation of the mineralisation. Every drill hole meter was sampled and assayed for gold and silver, using a 25g fire assay for gold and an aqua regia acid digest for silver. The most significant intersection encountered was in hole BDRC1001, which returned 9.00m @ 7.08g/t Au and 3.88 g/t Ag from surface, including 2.00m @ 24.74g/t Au and 14.15g/t Ag from 1.00m.
Additional significant intercepts included 5.00m @ 2.26 g/t Au and 1.88g/t Ag from 6.00m (hole BDRC1015) and 6.00m @ 3.02g/t Au and 0.64g/t Ag from 25.00m (hole BDRC1026). In contrast to the previous drilling by AGA, the VRX drilling returned results that (i) were of higher tenor than indicated by the previous work; (ii) pointed towards a more complex geology comprising not only granitoid but also folded metasedimentary and metavolcanic rocks; and (iii) suggested a possible E-W orientation of the mineralised trend (Ventnor Resources Limited, 2015b). In 2017, VRX embarked on a final 208m, thee hole RC drilling programme at the Black Dragon gold prospect as well as a 20,000 line km auger surface geochemical drilling program covering the Black Dragon-Red Dragon corridor, which outlined a significant, ca. 10km-long and up to 3km-wide, NE-SW-striking zone of surface gold anomalism that is spatially coincident with the Black Dragon shear zone as well as a >250km-structural feature in gravity data that also passes through Tropicana. No further work was undertaken since 2017.
Variability in gold grades between some original and repeat assays indicate the presence of coarse gold in the system, and that both historic rock chips and drilling results are significantly under-reported due to the absence of a more reliable assaying method (e.g., screen fire assays which sample both coarse and fine fraction gold from a larger sample size). This lack of effective sampling could have significant implications for the understanding of the orientation and morphology of the gold system.
Future work on the Black Dragon gold corridor includes more effective induced polarisation (dipole- dipole or offset pole-dipole rather than the existing gradient array data that has a very limited depth capacity), followed by the generation of a 3D targetable model of the system including all available geochemistry, geophysics and geology, drill hole planning and diamond drilling with appropriate sampling and assaying techniques (including 4Acid Digest for multi-element analysis and the use of screen fire or other more robust assaying techniques for high grade coarse gold systems).
Given the currently understood significant size potential and very high tenor of the known gold-silver- tellurium system, testing of the Black Dragon prospect becomes a very high priority for the company and will proceed in tandem with our nickel discovery programme.