Gravity Survey Completed at Earaheedy
- Rumble has completed a gravity survey over high-grade zinc and lead stratiform mineralisation identified through historic wide spaced drilling within carbonate sediments of the lower sedimentary units of the Earaheedy Basin (Proterozoic) in Western Australia.
- Historical drilling discovered high-grade zinc up to 18.6% within an intersection 3.3m @ 11.2% Zn, and 0.93% Pb from 150m and another drill hole intercepted 2m @ 8.23% Zn and 2.77% Pb from 103m that occurs in flat lying carbonates.
- Preliminary modelling has highlighted a number of gravity anomalies that are interpreted to parallel northwest trending basement structures.
- Detailed partial leach geochemistry is planned to cover the modelled gravity trends in March which will help delineate first order targets to be drill tested this year.
- Based on the wide spaced drilling, widespread flat lying zinc and lead mineralisation and significant high-grade intercepts, Rumble believes the potential for moderate to high angle fault breccias with significant/economic mineralisation is high.
- Rumble is targeting Mississippi Valley Type (MVT) high-grade base metal deposits similar to the Devonian Lennard Shelf Zn-Pb deposits of the Kimberley Region of Western Australia.
- Rumble has applied for additional tenure that potentially covers the southeast extension of stratiform zinc and lead mineralisation.
Gravity targets associated with inferred northwest trending basement faults/structures have been identified. The gravity targets will be tested by partial leach base metal geochemistry to aid in defining mineralised faults which will help delineate first order targets to be drill tested this year. An additional exploration license (ELA69/3543) has been applied for to cover potential extension of stratiform zinc and lead mineralisation to the southeast of the current Earaheedy project area.
About the Earaheedy Project (Image 1 in link below) - Option to Acquire 75%
Rumble has an option agreement with Fossil Prospecting Pty Ltd (a wholly owned subsidiary of ASX Listed Zenith Minerals Ltd - (ASX:ZNC)) to acquire a 75% interest in the Earaheedy Project, as previously announced on 12 October 2017.
The Earaheedy High Grade Zinc Project (E69/3464) is located approximately 110km north of Wiluna, Western Australia. Zinc and lead mineralisation with elevated silver is associated with the Navajoh Dolomite Member (also known as the Sweetwaters Well Member) of the Yelma Formation. The Yelma Formation is the lower unit of the 5000m thick Earaheedy Basin (Palaeoproterozoic). Sphalerite, galena, pyrite and marcasite (coarse grain) occurs as stratiform/stratabound ore fill veins and breccias, dissolution cavity fill, disseminated, stylolitic and fault fill mineralisation styles.
Broad spaced drilling (completed in the 1990's) defined several prospects containing oxidised and primary Zn-Pb mineralisation (zinc dominant) associated with a flat lying to shallow northeast dipping laterally continuous dolomite horizon with over 20 kilometres strike. The initial drill spacing was 5 to 10km. The current drill spacing is approximately 1km by 1km. Three prospects were defined within granted tenement E69/3464 (see image 2 in link below).
At 'Navajoh', an intersection of 7.3 metres @ 6.1 % Zn, 0.77% Pb (including 3.3 metres @ 11.2% Zn, and 0.93% Pb) remains untested for 500 metres to 1 kilometre in all directions.
At 'Magazine' there are no follow up holes within a 1kilometre radius of a discovery intersection of 11 metres @ 3.5% (Zn + Pb) which includes 2 metres @ 8.2% Zn, 2.8% Pb).
At 'Chinook' intersections include 9 metres @ 3.54% Zn, 0.58% Pb.
Review of the historic drilling has concluded that approximately half the drill holes did not intercept the target horizon. A total of 64 drill holes were completed within the project area (E69/3464) with only 35 drill holes intercepting the stratiform zinc horizon (including partial end of hole intercepts).
Rumble completed additional structural interpretation from magnetics and also completed a study on the relationship of metal zonation with respect to Zn:Pb ratios determined from drillhole data. Rumble considers the exploration model for the Earaheedy Project to be analogous to well-known MVT (Mississippi Valley Type) base metal deposits worldwide.
Based on the wide spaced drilling, widespread flat lying zinc and lead mineralisation and significant high-grade intercepts (3.3m @ 11.2% Zn), the potential for moderate to high angle fault breccias with significant/economic mineralisation is high.
The target size is 10Mt, similar to the Pillara (Blendevale) Zn - Pb deposit located in the Devonian limestones of the Lennard Shelf, Kimberley Region, Western Australia. The Pillara deposit produced 10.3 Mt @ 6.9% Zn and 2.3% Pb. Of note, the discovery drill-hole (8m @ 8.9% Zn, 3.5% Pb below 210m) at Pillara, was the 136th drill hole in the area.
Gravity Survey Completed by Rumble
The gravity survey comprised of 556 stations on a 200m by 200m grid covering an area of 20km2. Terrain corrections were applied to the final Bouger gravity (2.5g/cc).
The gravity survey was designed to cover the interpreted strong zinc metal endowment as defined by structural contouring (Zn%-m) - see image 2 in link below - along with higher grade Zn drilling intercepts within the south-eastern portion of granted tenement E69/3463.
Preliminary interpretation of the gravity data outlined a number of non-magnetic and non-topographic related gravity anomalies and trends that lies close to both northwest (basement faults) and northeast (cross faults) structures (see image 4 in link below). Surface geochemistry is planned to cover the gravity anomalies and trends.
Next Steps of Exploration
Historic exploration has shown the flat lying zinc and lead mineralisation does not surface and is essentially "blind". All historic exploration drilling passed through iron formations and shale of the Frere Formation before intercepting the host dolomite of the Yelma Formation. The mineralised dolomite was intercepted at a vertical depth of 50 to 70m to the southwest (see image 2 in link below). No systematic surface geochemistry has been completed.
Partial leach geochemistry is planned in March to cover the gravity trends and anomalies with the aim to help delineate base metal leakage haloes associated with potential mineralised fault breccias.
The partial leach geochemistry will help prioritise gravity/structural high-grade zinc targets for drilling this year.
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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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