High Grade Zinc Discovery Confirmed with Vanadium Potential
Perth, Feb 22, 2018 AEST (ABN Newswire) - Rumble Resources Ltd (
ASX:RTR) ("Rumble" or "the Company") is pleased to announce that the completion of re-split assaying of previous composites and additional composite sampling from the maiden reconnaissance drilling program (completed Dec 2017) at the Braeside Project (E45/2032) has confirmed high grade zinc mineralisation at the Devon Cut Prospect and identified high-grade vanadium potential.
Highlights
Devon Cut Prospect High-Grade Zinc Discovery
Re-assaying of composites samples and additional multi-element analysis has confirmed the Devon Cut Prospect (tested by a single RC drill hole within a 2km zinc soil anomaly) as a significant discovery and has identified high-grade vanadium potential.
- The high-grade zone returned 5m @ 8.0% Zn, 0.35% Pb from 32m within a broad zone of lower grade zinc mineralisation which returned 30m @ 1.5% Zn from 28m.
- Strong alteration (silica - sericite - chlorite) is associated with the base metal mineralisation. Alteration extends from 17m to 88m EOH. Elevated Hg (mercury) and In (indium), indicative of high level porphyry related base metal systems, is associated with the high grade Zn mineralisation.
- Grab sampling near the Devon Cut Prospect returned high-grade vanadium which is inferred to be related with a large mafic dyke system intrusion (magnetic and vanadiferous) that occurs immediately west of the Devon Cut zinc mineralisation.
o Grab sampling results include high grade 3.29%, 1.82% and 1.52% V2O5.
o The Devon Cut discovery hole intercepted 3m of vanadium anomalism from 53m within altered andesitic basalt.
Braeside Potential
- The base metal mineralisation extends for 34km strike within E45/2032 and is completely open with the mineralisation associated with two main structures from the Ragged Hills Mine to the south all the way through to north, with up to four strongly mineralised structures occurring over a 5km wide corridor (north of the Devon Cut Prospect).
- Within the E45/2032 tenement there are eleven (11) groups of significant base metal in soil anomalism, of these groups, only four (4) have been partly tested with the latest reconnaissance RC drilling. E45/2032 represents approximately 15% of the total Braeside Project (>1000km2).
- The single drill hole testing the Barker Well Prospect area intercepted 124m @ 0.19% Pb, 900ppm Zn (no lower cut-off) over the entire hole length in association with pervasive silica-sericite-chlorite alteration. The intercept is considered very significant as it indicates the fluids were consistently metal rich and the flow was voluminous to allow the pervasive alteration of the host rock (andesitic basalt) in association with fracture/feeders likely related to a deeper porphyry source.
- Rumble is targeting high-grade fault breccia pipe type deposits (2-5Mt of high-grade Zn and Pb). In addition to this target type, recent sampling has shown that base metal mineralisation is closely associated with wide zones of alteration, in the case of Barker Well Prospect, over 100m in width. Rumble considers there is potential for larger tonnage lower grade disseminated base metal deposits (30-50Mt).
Additional assaying included multi-element analysis of the high-grade zinc mineralisation. Further grab samples were collected at the Devon Cut, Sugar Ramos and North Ragged Hills prospects.
About the Braeside Project
The Braeside Project lies 140km east of Marble Bar and is located on the eastern margin of the Pilbara Craton in the northwest of Western Australia (see image 1 in link below). The project hosts the Braeside Pb-Ag-Zn mining district which includes the Ragged Hills mining centre (discovered in 1901) and numerous small mines along a series of north trending structures (informally called the Braeside Fault Zone - BFZ). The historic mines were operative from 1925 to 1967. The BFZ contains high grade poly-metallic mineralisation over 34km of strike with dominant galena and associated sphalerite and chalcopyrite. The BFZ and associated mineralisation are hosted in Fortescue Group mafic volcanics and volcaniclastics (Maddina Basalt and the Kylena Basalt). The Koongaling Felsic Volcanics sequence is the same age as the Kylena Basalt (bimodal) and lies further east.
Rumble has the right to earn 70% of granted licence E45/2032 and holds 100% of 5 contiguous exploration licences (under application). To the north of the granted licence, Rumble has an option on the Barramine Project which lies along strike from the BFZ. The total area of prospective terrane for high grade Zn-Pb Cu, Ag and Au deposits is now over 1000km2.
Prior to Rumble's acquisition of the high-grade project there had been no modern systematic exploration on the project.
During 2017, Rumble completed the first ever modern systematic exploration on the Braeside project.
The systematic exploration program included soil sampling (regional and infill), Heli - VTEM and prospect geological mapping with grab sampling which generated thirteen (13) targets that were subsequently tested by nineteen (19) first pass reconnaissance RC drill holes. Significantly in the maiden RC Drilling program at the Braeside Project, seventeen (17) of the drill holes intersected anomalous Zn-Pb mineralisation with eight (8) of the targets delineating significant Zn-Pb (> 1% Pb/Zn) mineralisation along with a new zinc discovery at the Devon Cut Prospect.
Pervasive widespread silica-sericite-chlorite alteration with potassic (Kspar), hematite and magnetite is associated with the major fault/fracture zones - BFZ - which host widespread disseminated to massive base metal mineralisation over the entire 34 km strike. The structures are likely laterally extensive feeders associated with known sub volcanic rhyolites that outcrop further to the east. Research and litho-geochemical studies by Rumble has shown mineralisation (Pb dating), the rhyolite and the host andesitic basalt are approximately the same age.
The porphyry related base metal geological/deposit model developed by Rumble has been supported by the latest multi-element geochemistry which has highlighted elevated mercury and indium with the high-grade Zn mineralisation.
The latest round of grab sampling has returned high-grade vanadium assays from the Devon Cut prospect area. Regional mapping and interpretation has outlined an extensive north trending mafic dyke sequence (both cross cutting and conformable to lithologies) which is magnetic and vanadiferous.
Additional Sampling and Multi-Element Analysis
During January 2018, a total of 485 RC chip samples were assayed. Sampling included 1 metre re-splits of composites and additional composite sampling from the entire nineteen (19) hole RC drilling programme that was conducted in November-December 2017. Select detailed multi-element analysis (18 samples) was completed on the higher-grade base metal mineralisation. Further grab sampling (12 samples) was completed on the Devon Cut, Sugar Ramos and Ragged Hill North prospect areas.
Devon Cut Prospect (BRRC019) - New Zinc Discovery (see image 2 & 3 in link below)
Single metre re-sampling of previous composite samples and multi-element analysis returned:
- 5m @ 8.0% Zn, 0.35% Pb from 32m
inc 1m @ 21% Zn, 0.97% Pb from 34m.
The high-grade intercept was within a broad zone of zinc anomalism:
- 30m @ 1.5% Zn from 28m
Strong silica-sericite-chlorite-hematite alteration was intercepted from 17m to end of hole (88m). Geological interpretation from logging and position of high grade mineralisation at surface indicates that the high-grade intercept is approximate true width. Multi-element analysis of the high-grade intercept returned up to 21.3 ppm Hg (mercury) and 16 ppm In (indium).
Mineralisation at the Devon Cut is completely open along strike and down dip.
Grab sampling at the Devon Cut Prospect returned high grade vanadium:
V2O5 - 3.29%, 1.82% and 1.52%
BRRC019 intercepted weak vanadium anomalism from 53m (0.095% V2O5). Geological investigation has highlighted a mafic intrusion immediately west of the Devon Cut Prospect mineralisation (BRRC019 did not intercept the mafic intrusion). The intrusion (dyke) is gabbroic to tonalitic in composition and is strongly magnetic.
Anomalous vanadium in soil geochemistry elsewhere within E45/2032 has been observed with up to 560ppm V2O5 over or nearby the inferred position of the mafic dyke.
With rock chip samples reporting high grade vanadium, the mafic intrusion is considered significant and further work is planned for this year.
Results of the Re-Assaying and Composite Sampling - RC Drilling
Of the nineteen (19) drill holes sampled, seventeen (17) drill holes returned anomalous base metal intercepts (mineralisation >1000 ppm Zn and/or Pb), with eight (8) of the drill holes discovering significant Zn-Pb mineralisation along with a new zinc discovery at the Devon Cut Prospect - (see above). The re-assaying of the previous composites as one metre samples has confirmed the previously reported lower grade intercepts, however, more importantly, it has highlighted that the widespread base metal anomalism is closely associated with the pervasive alteration.
The single drill hole testing the Barker Well Prospect area (BRRC036) returned anomalous Pb and Zn over the entire length (124m) in association with pervasive silica-sericite-chlorite alteration.
The drill hole returned an intercept of 124m @ 0.19% Pb, 900ppm Zn from surface (no lower cut-off).
This is very significant as it indicates the fluids were consistently metal rich and the flow was voluminous to allow the pervasive alteration of the host rock (andesitic basalt) over significant widths (>100m wide) in association with fracture/feeders likely related to a deeper porphyry source.
Multi-element Geochemistry
In general, the Braeside mineralisation is zinc (sphalerite) and/or lead (galena) dominate with associated copper, silver and minor gold. Other elevated elements include Mo (molybdenum), Hg (mercury) and In (indium). Indium is directly associated with sphalerite (indium is a common by-product of zinc). Anomalous Ba (barium) is observed with higher grade galena (Pb) without sphalerite (Zn).
The high-grade vanadium is likely associated with a series of mafic intrusions trending north-south. The mafic dykes appear to be later than the main altered structures/feeders hosting the dominant Zn and Pb mineralisation as they often intrude along the same zones. Later veining (epigenetic veining commonly overprints the main mineralised structures) has potentially upgraded the vanadium at the Devon Cut Prospect.
Of the main oxide elements, K (potassium) is strongly associated with Ba and is often elevated in the hanging wall and footwall to the main base metal mineralisation. Kspar has been often observed along with muscovite within the alteration zones.
Summary of Mineralisation and Target Type
The latest sampling and multi-element analysis of RC drilling completed last December has reinforced the geological/exploration model developed by Rumble. The Braeside base metal mineralisation is likely associated with wide pervasively altered fracture/fault zones which are feeder faults associated with porphyritic rhyolite. The highlights are:
- The base metal mineralisation extends for 34km within E45/2032 and is completely open.
- The mineralisation is associated with two main structures at the Ragged Hills Mine (southern end of granted tenement E45/2032) and further north, up to four strongly mineralised structures occur over a 5km wide corridor (north of the Devon Cut Prospect).
- The new Zn discovery at Devon Cut has been confirmed by the latest sampling. The high-grade intercept (5m @ 8.0% Zn, 0.35%Pb) within a broad altered lower grade intercept (30m @ 1.5% Zn) is considered very significant considering the reconnaissance nature of the single RC drill hole. The discovery lies within a 2km long Zn and Pb soil anomaly that is completely open along strike and at depth.
- Base metal mineralisation is associated with significant widths of alteration. At the Barker Well Prospect, the alteration is >100m in width and is anomalous in base metals (124m @ 0.19% Pb - entire hole).
The target for Rumble is high-grade fault breccia pipe type deposits (2-5Mt of high-grade Zn and Pb), however, based on the recent re-assaying which has shown that base metal is closely associated with wide zones of alteration, in some cases > 100m in width, there is also potential for larger tonnage lower grade disseminated base metal deposits (30-50Mt).
Soil Geochemistry and Future Targeting
Soil sampling conducted during 2017 has been the most effective tool to highlight the base metal mineralised trends and structures. Follow up grab sampling has been limited to only a small percentage of the available Zn/Pb soil anomalies and in most cases, grab sampling has confirmed mineralisation within the soil anomalies with high-grade base metal values.
Granted tenement E45/2032 represents approximately 15% of the total project area (including the Barramine option) and within the tenement there are eleven (11) groups of significant base metal in soil anomalism (see image 5 in link below). Of these groups, only four (4) have been partly tested with the latest reconnaissance RC drilling. In the case of the Devon Cut and Barker Well Prospects, only single holes have been completed (both returned very significant mineralisation including a new Zn discovery).
To put into context the high level of prospectivity for the Braeside Project, the soil anomaly associated with the Devon Cut Zn (with Pb) discovery is approximately two (2) km long (see image 5 in link below). Elsewhere in E45/2032, significantly larger base metal anomalies (multiple zones with strike lengths up to 8km) have yet to be tested.
Note that image 5 (see link below) uses Pb in soil contouring for targeting as Pb is less geochemically mobile in the surface profile than Zn and therefore Pb anomalism is likely closer to the source of the base metal mineralisation.
Future Exploration
Next stages for the 2018 systematic exploration field season includes:
- Detailed geochemistry (soil and grab sampling) and geological mapping of the strong base metal mineralisation discovered by the recent RC drilling with the aim to delineate the newly discovered mineralisation and generate further drill targets.
o Focus will be on the Devon Cut and Barker Well Prospects.
- Detailed geochemistry and geological mapping of new targets to generate new drill targets.
o As previously reported (announcement 16th Oct 2017 - Numerous High-Grade Zn - Pb - Cu - Ag - Au - V Targets Identified at Braeside Project from Infill Soil and Rock Chip Sampling), many base metal and Au soil anomalies and targets have been defined within E45/2032 and remain untested.
o The high grade vanadium potential will be also investigated.
- First pass geochemistry (soil, stream sediment and grab sampling) of newly granted tenements within the Braeside Project area.
- It is anticipated there will be 2 rounds of drilling in 2018 with the next round of drilling scheduled for May 2018 (subject to wet season).
To view figures, please visit:
http://abnnewswire.net/lnk/R311T52M
About Rumble Resources Ltd
Rumble Resources Limited (ASX:RTR) (FRA:20Z) is an Australian based exploration company, officially admitted to the ASX on the 1st July 2011. Rumble was established with the aim of adding significant value to its current gold and base metal assets and will continue to look at mineral acquisition opportunities both in Australia and abroad.
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