Mineral Deposit Type Target(s)
- Multiple large-scale (large tonnage) sandstone hosted flat lying Zinc-Lead-Silver sulphide deposits that are amenable to open cut mining.
The Earaheedy project is located approximately 110km north of Wiluna, Western Australia. Rumble owns 75% of E69/3464 and Zenith Minerals Ltd (ASX: ZNC) owns 25%. Rumble also has a single contiguous exploration license application, ELA69/3787 that is held 100%. The project area covers the inferred unconformity contact between the overlying Frere Iron Formation and underlying Yelma Formation of the Palaeoproterozoic Earaheedy Basin.
Image 1 – Regional Geology and Tenement Location Plan – Earaheedy Project
Sandstone Hosted Zinc-Lead-Silver Discoveries
RC drilling by Rumble discovered the Chinook and Magazine prospects. The prospects are two shallow, flat lying, large-scale unconformity related sandstone hosted Zn-Pb-Ag discoveries made by Rumble in January 2020.
Large Scale Zn-Pb-Ag Deposit Potential
- At Chinook, higher-grade Zn-Pb confirmed over 200m horizontal width and up to 12m vertical true thickness (within 41m Zn-Pb broad zone)
- Magazine and Chinook are 10.5km apart with the Zn-Pb-Ag mineralisation completely open
- The Project covers over 40km of sandstone unconformity prospective strike – remains untested and completely open
- Higher-grade Zn-Pb identified in sandstone channel and facies zones which are conducive to developing higher-grade Zn-Pb mineralisation – New Target Zones
- All these points combined highlights the potential for multiple large tonnage, flat lying, shallow deposits and supports the exploration target1
Image 2 – Earaheedy Project – Location of Prospects with Recent Significant Drill Hole Intersections
Chinook Zn-Pb-Ag Prospect
Strong continuity of flat lying Zn-Pb confirmed with:
- *12m @ 3.39% Zn + Pb, 4 g/t Ag from 84m (EHRC022) including 4m @ 5.44% Zn + Pb, 6.5 g/t Ag from 85m
Mineralisation lies within a broad zone of:
- *18m @ 2.44% Zn + Pb from 83m
EHRC022 lies 200m northeast of discovery hole EHRC019 (completed by Rumble Jan 2020) which returned:
- *11m @ 4.13% Zn + Pb, 12.78 g/t Ag from 61m (EHRC019)1 including 5m @ 4.7% Zn + Pb from 65m
Mineralisation (EHRC019) lies within a very wide zone of
- *41m @ 1.41% Zn + Pb from 37m
Important: *indicates true width of mineralisation
Image 3 – Chinook Prospect – Discovery Section – Assay Results
Image 4 – Chinook Prospect – Plan Highlighting Inferred Zone of Higher-Grade Mineralisation over Airborne Magnetic Image (TMI)
Magazine Zn-Pb-Ag Prospect
- Higher grade flat lying (up to 12.65% Zn + Pb) has been confirmed with:
- 12m @ 4.48% Zn + Pb, 2.91 g/t Ag from 88m (EHRC034) including 4m @ 7.36% Zn + Pb, 4.43 g/t Ag from 88m
- The new intersection confirms nearby historic Zn-Pb:
- 7m @ 4.85% Zn + Pb from 103m (TRC47) including 2m @ 11.0% Zn + Pb from 103m
Image 5 – Magazine Prospect – EHRC034 Section – Assays Results
Image 6 – Magazine Prospect – Plan Highlighting Potential Higher-Grade Zone
Rumble’s Zn-Pb Exploration Target at the Earaheedy Project is between 40 to 100 million tonnes at a grade ranging between 3.5% Zn-Pb to 4.5% Zn-Pb. The Exploration Target is at a shallow depth (80m), and over 40kms of prospective strike (completely open) has been defined within the Earaheedy Project. The potential quantity and grade of the Exploration Target is conceptual in nature, there has been insufficient exploration to estimate a Mineral Resource and it is uncertain if further exploration will result in the estimation of a Mineral Resource.
The Exploration Target, being conceptual in nature, takes no account of geological complexity, possible mining method or metallurgical recovery factors. The Exploration Target has been estimated in order to provide an assessment of the potential for large-scale Zn-Pb deposits within the Earaheedy Project. The Exploration Target has been prepared and reported in accordance with the 2012 edition of the JORC Code.
|Earaheedy Zn-Pb Project – Exploration Target
Table 1 – Near Surface Exploration target down to 80 metre – Shallow Depth
The Exploration Target is based on the current geological understanding of the mineralisation geometry, continuity of mineralisation and regional geology. This understanding is provided by an extensive drill hole database, regional mapping, coupled with understanding of the host stratigraphic sequence and a feasibility study completed at the nearby Paroo Pb deposit. Included in the data on which this Exploration Target has been prepared is recent RC drilling of 30 holes for 2690m (three RC stages) and Diamond Drilling of 4 holes for 1199.8m completed by Rumble along with 64 historic RC drill holes completed within the project area (E69/3464) by previous explorers (refer historical exploration results in previous ASX announcements dated 5 February 2019 and 12 October 2017, 23rd January 2020 which continue to apply and have not materially changed). Some of the considerations in respect of the estimation of the Exploration Target include:
- Drilling results have demonstrated strong continuity of shallow, flat lying mineralisation;
- Over 40km’s of prospective strike and open;
- Minimum 200m of width (based on shallow 7.5° and shallow depth to 80m, based on drilling results.
- True width of mineralisation up to 12metres received in drilling results; and
- Specific gravity (SG) of 2.5 (world average SG of sandstone – not accounting for metal).
The Company intends to test the Exploration Target with drilling and this further drilling is expected to extend over approximately 12 months. Grade ranges have been either estimated or assigned from lower and upper grades of mineralisation received in drilling results. A classification is not applicable for an Exploration Target.
Rumble has developed a new geological model for the Earaheedy Zn-Pb project based on recent drilling and geophysics (passive seismic survey).
The sandstone hosted Pb-Zn deposit model is considered different than the previous known Mississippi Valley Type (MVT) where earlier explorers focused on the Zn dominant disseminated/replacement carbonate hosted mineralization that occurs extensively throughout the Sweetwater Dolomite unit (upper Yelma Formation).
Rumble considers the hiatus between the Frere Iron Formation (overlying formation) and the Yelma Formation involved a stripping stage (including karstification) which partly eroded the mineralized dolomite. The early stages of sedimentation of the Frere Iron Formation developed small higher energy sub basins (coarser material) which physically stripped the dolomite which attributed to the release of a combination of physical and chemical Zn and Pb. Galena and sphalerite remobilized and re-deposited in these porous sandstone dominated sub basins.
This process likely occurred during and after the development of the Frere Iron Formation and later sedimentation cycles. The Pb:Zn ratio increases spatially away from the Zn dominant underlying dolomites.
Seismic and the re-interpretation of detailed gravity has inferred a number of channel systems developed during the formation of the sandstone sub basins.
The channels typically have coarser grained sandstone facies and porosity which would allow space for higher grade Pb – Zn mineralization to develop. Image 6 presents a graphical interpretation of the new geological model.
Image 7 – Geological Model for Sandstone Hosted Zn – Pb Deposits (Earaheedy Project)