REG - Cobra Resources PLC - Wudinna Project Update
21/02/2023 07:00
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RNS Number : 5539Q Cobra Resources PLC 21 February 2023
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21 February 2023
Cobra Resources plc
("Cobra" or the "Company")
Wudinna Project Update
CSAMT Geophysics Defines Further Gold and REE Associations;
Highlights Additional Priority Targets To Be Tested in Planned Drilling
Cobra, a gold, rare earth and IOCG exploration company focused on the Wudinna
Project in South Australia, is pleased to provide an update on results of the
Controlled Source, Audio-Frequency Magnetotelluric ("CSAMT") and Natural
Source Audio Frequency Magnetotelluric ("AMT") surveys at the Clarke prospect.
As a result of the surveys, seven additional targets with structural
similarities and corresponding to anomalous gold in calcrete will be tested in
an upcoming drilling programme scheduled to commence in March.
Summary Interpretation and Implications of the CSAMT Survey
· Increases in saprolite depth are locally related to structures
containing gold mineralisation, hydrothermal alteration, sulphides and
subsequently elevated rare earths. Deeper weathering profiles are considered
to be a product of acidic weathering conditions that result from the presence
of sulphides
· Immediately adjacent to the interpreted Clarke gold-bearing
structure, a zone of moderate conductivity is interpreted to reflect sodic
alteration associated with gold mineralisation
· Regional, unmineralised structures display different geophysical
responses to localised mineralised structures. These include shallow saprolite
weathering and strong conductive down-plunge responses that are thought to be
related to the presence of saline groundwater
· Gold mineralisation is contained in second order structures where
dilation is likely increased by the relative proximity to primary structures,
and alteration subsequently yields a de-magnetised geophysical response
· Structural observations made through the CSAMT survey have been
applied to the regional Airborne Electromagnetic ("AEM") survey conducted by
Newmont in 2004. A number of demagnetised zones are interpreted to contain
first and second order structures and are comparable to the structural
interpretation at the dual gold and rare earth Clarke prospect
· Results support basement interpretations and structural inferences
derived from the Loupe TEM survey completed in November 2022
· Seven additional targets with structural similarities and
corresponding to anomalous gold in calcrete will be tested in an upcoming
drilling programme scheduled to commence in March
· Both Reverse Circulation ("RC") and Aircore drilling programmes will
be executed in concurrence, designed to expand both gold and REE resources
The CSAMT and AMT surveys were co-funded by the South Australia Accelerated
Discovery Initiative ("ADI").
Rupert Verco, CEO of Cobra, commented:
"The CSAMT survey has enabled us to evaluate and discern differences between
mineralised and un-mineralised features. We have applied these findings to our
regional dataset and have defined several prospective targets that we look
forward to testing in our upcoming drilling programmes.
RC drilling will focus on adding gold ounces to our resource, where we plan to
extend mineralisation at Clarke and test extensions at Barns and White Tank.
We also plan to execute a regionally extensive Aircore programme targeting
rare earth resource growth at Clarke and Thompson whilst testing these
regional gold targets.
We are grateful for the South Australian Government's support in this
initiative, which will be invaluable in accelerating the definition of our
multi-commodity project, and we are fortunate to be working in a jurisdiction
supportive of mineral exploration and advancing exploration technologies."
March 2023 Drilling Programme
Commencing in March, Cobra will execute a significant dual-pronged drilling
programme aimed at expanding complementary gold and rare earth resources,
where 2,000-3,000m of RC drilling will:
· Target near-resource extensions at Barns and White Tank gold
prospects
· Test further strike and depth extensions at the defined 600m of
mineralised gold strike at the Clarke prospect
· Enable gold mineralisation at Clarke to be incorporated into an
updated mineral resource estimate
5,000-7,000m of Aircore drilling will:
· Target expansion of the 20.9 Mt Rare Earth JORC Resource at Clarke
and Baggy Green by targeting identified zones of deep saprolite generation
where acidity and clay formation are considered important catalysts for clay
adsorption of rare earths
· Infill drilling at the Thompson 81-233 Mt REE Exploration Target
· Test targets generated by the CSAMT survey, prospective for both gold
and rare earth mineralisation
Enquiries:
Cobra Resources plc via Vigo Consulting
Rupert Verco (Australia) +44 (0)20 7390 0234
Dan Maling (UK)
SI Capital Limited (Joint Broker) +44 (0)1483 413 500
Nick Emerson
Sam Lomanto
+44 (0)20 7186 9952
Shard Capital Limited (Joint Broker)
Erik Woolgar
Damon Heath
Vigo Consulting (Financial Public Relations) +44 (0)20 7390 0234
Ben Simons
Charlie Neish
Kendall Hill
The person who arranged for the release of this announcement was Rupert Verco,
Managing Director of the Company.
About Cobra
Cobra is defining a unique multi-mineral resource at the Wudinna Project in
South Australia's Gawler Craton, a tier one mining and exploration
jurisdiction which hosts several world-class mines. Cobra's Wudinna tenements,
totalling 3,261 km(2), contain extensive orogenic gold mineralisation and are
characterised by potentially open-pitable, high-grade gold intersections, with
ready access to infrastructure. Cobra has 22 orogenic gold targets outside of
the current 211,000 Oz gold JORC Mineral Resource Estimate. In 2021, Cobra
discovered rare earth mineralisation proximal to and above the gold
mineralisation which has been demonstrated to be regionally scalable. In 2023,
Cobra published a maiden rare earth JORC Mineral Resource Estimate of 20.9 Mt
at 658 ppm Total Rare Earth Oxides enabling a strategic baseline to advance an
economically beneficial combination of gold and rare earth resources.
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(https://twitter.com/Cobra_Resources)
Subscribe to our news alert service: https://cobraplc.com/news/
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Competent Persons Statement
Information and data presented within this announcement has been compiled by
Mr Robert Blythman, a Member of the Australian Institute of Geoscientists
("MAIG"). Mr Blythman is a Consultant to Cobra Resources Plc and has
sufficient experience, which is relevant to the style of mineralisation,
deposit type and to the activity which he is undertaking to qualify as a
Competent Person defined by the 2012 Edition of the Australasian Code for
Reporting Exploration Results, Mineral Resources and Ore Reserves (the "JORC"
Code). This includes 10 years of Mining, Resource Estimation and Exploration
relevant to the style of mineralisation.
Information in this announcement has been assessed by Mr Rupert Verco, a
Fellow of the Australasian Institute of Mining and Metallurgy ("FAusIMM"). Mr
Verco an employee of Cobra Resources Plc has more than 16 years relevant
industry experience, which is relevant to the style of mineralisation, deposit
type and to the activity which he is undertaking to qualify as a Competent
Person as defined in the 2012 Edition of the Australasian Code for Reporting
Exploration Results, Mineral Resources and Ore Reserves (the "JORC" Code).
This includes 11 years of Mining, Resource Estimation and Exploration.
APPENDIX
Figure 1: CSAMT line 8 section at the Clarke prospect - cool colours indicate
high resistivity and warm colours indicate low resistivity. Significant gold
intersections highlighted in red
Figure 2: CSAMT Survey sections at the Clarke prospect overlain by the
regional magnetics
Figure 3: Areas of demagnetisation relating to priority structural targets to
be tested by planned Aircore drilling
About CSAMT
Controlled Source Audio-Frequency Magnetotelluric is a low impact,
non-intrusive, ground geophysical survey method used to measure sub-surface
resistivity. The survey involves transmitting a controlled signal at given
frequencies into the ground from one location (transmitter) and measuring the
electric and magnetic responses at receiving points. The ratios of orthogonal,
horizontal electric and magnetic field magnitudes are used to calculate the
resistivity structure of the earth.
CSAMT provides better resolution and much greater penetration than alternate
methods such as IP surveys. The resistive variances in the geology enable
structures, lithology and groundwater to be modelled.
Clarke Survey Details
The survey has been co-funded through the South Australian ADI. From November
to December 2022, Zonge Engineering and Research Organisation Australia
conducted a CSAMT survey at the Clarke prospect. A total of 12.6 line
kilometres of data was collected over the course of the survey.
Each CSAMT/AMT receiver array consisted of up to seven E-field dipoles and a
single H-field antenna at a station spacing of 25m. Data was recorded over a
frequency range from 4 to 8192 Hz. Distance between receiving lines and
transmitter dipole ranged from 6.5-8.5 km. The maximum transmitter current was
31 amps.
JORC Code, 2012 Edition - Table 1 report template
Section 1 Sampling Techniques and Data
(Criteria in this section apply to all succeeding sections.)
Criteria JORC Code explanation Commentary
Sampling techniques · Nature and quality of sampling (eg cut channels, random chips, or · Results presented in this release relate to CSAMT and AMT data
specific specialised industry standard measurement tools appropriate to the obtained in a survey completed in December 2022.
minerals under investigation, such as down hole gamma sondes, or handheld XRF
instruments, etc). These examples should not be taken as limiting the broad · Zonge Engineering and Research Organization conducted 12.6 line
meaning of sampling. kilometers over 14 days using a Zonge multipurpose GDP-32/24 receiver and a
Zonge GGT-30 geophysical transmitter. The transmitter was powered by a ZMG-30
· Include reference to measures taken to ensure sample representivity generator system. Signal frequency and synchronization was controlled by an
and the appropriate calibration of any measurement tools or systems used. XMT-32 controller with the receiver and controller synchronized daily.
· Aspects of the determination of mineralisation that are Material to · Grounded, porous ceramic pots filled with copper sulphate were
the Public Report. used to collect electric field data. CSAMT and AMT magnetic-field data were
sensed using EMI ANT6 coils. Receiver arrays were constructed with 2.5mm
· In cases where 'industry standard' work has been done this would be insulated copper wires.
relatively simple (eg 'reverse circulation drilling was used to obtain 1 m
samples from which 3 kg was pulverised to produce a 30 g charge for fire · Each receiver array consisted of up to seven E-field dipoles with
assay'). In other cases more explanation may be required, such as where there one central H field antenna. Data from each channel were recorded
is coarse gold that has inherent sampling problems. Unusual commodities or simultaneously to provide scalar" TM mode" coverage across each line.
mineralisation types (eg submarine nodules) may warrant disclosure of detailed
information. · CSAMT data were recorded over the frequency range from 4 to 8192
Hz.
· AMT data were taken at each of the CSAMT receiver positions to
collect deeper information as the CSAMT data alone did not penetrate to the
desired depths.
· The distance between the receiving lines and transmitter dipole
ranged from 6.5-8.5km.
· Maximum transmitter current was approximately 31 amps.
· 9 lines of 1400m were analysed with station spacings of 25m and a
total of 504 stations of data collected.
· raw CSAMT data quality was assessed using the Zonge CSAVGW
software
· Unreliable data was removed from processing but has been retained
in the raw data set
· AMT time series data were processed using Zonge's MTedit
software. Raw time series data were filtered then Fourier coefficients
calculated for each frequency. These were then processed as impedance data
over the frequency range 1 - 8192Hz. AMT impedance phase data were used to
smooth and interpolate portions of the AMT apparent resistivity curve where
resistivity data was not of sufficient quality.
· AMT scalar soundings were merged with far-field scalar CSAMT
soundings to produce complete far-field scalar soundings for each station over
the 1-8192Hz range. Data from 1-256Hz were derived from the AMT and data from
256-8192Hz were derived from the CSAMT.
· All soundings were averaged, merged, and then inspected using
Zonge ASTATIC software for final QC before static corrections on apparent
resistivity data were calculated.
· Final average files were input into Zonge SCS2D AMT inversion
modelling software.
· Topographic information used in modelling the data have been
extracted from NASA's SRTM data setwith a 30m lateral resolution and an 8m
vertical accuracy.
·
Drilling techniques · Drill type (eg core, reverse circulation, open-hole hammer, rotary · Not applicable - no drilling is reported
air blast, auger, Bangka, sonic, etc) and details (eg core diameter, triple or
standard tube, depth of diamond tails, face-sampling bit or other type,
whether core is oriented and if so, by what method, etc).
Drill sample recovery · Method of recording and assessing core and chip sample recoveries and · Not applicable - no drilling is reported
results assessed.
· Measures taken to maximise sample recovery and ensure representative
nature of the samples.
· Whether a relationship exists between sample recovery and grade and
whether sample bias may have occurred due to preferential loss/gain of
fine/coarse material.
Logging · Whether core and chip samples have been geologically and · Not applicable - no drilling is reported
geotechnically logged to a level of detail to support appropriate Mineral
Resource estimation, mining studies and metallurgical studies.
· Whether logging is qualitative or quantitative in nature. Core (or
costean, channel, etc) photography.
· The total length and percentage of the relevant intersections logged.
Sub-sampling techniques and sample preparation · If core, whether cut or sawn and whether quarter, half or all core · Not applicable - no drilling is reported
taken.
· If non-core, whether riffled, tube sampled, rotary split, etc and
whether sampled wet or dry.
· For all sample types, the nature, quality and appropriateness of the
sample preparation technique.
· Quality control procedures adopted for all sub-sampling stages to
maximise representivity of samples.
· Measures taken to ensure that the sampling is representative of the
in situ material collected, including for instance results for field
duplicate/second-half sampling.
· Whether sample sizes are appropriate to the grain size of the
material being sampled.
Quality of assay data and laboratory tests · The nature, quality and appropriateness of the assaying and · Not applicable - no drilling is reported
laboratory procedures used and whether the technique is considered partial or
total.
· For geophysical tools, spectrometers, handheld XRF instruments, etc,
the parameters used in determining the analysis including instrument make and
model, reading times, calibrations factors applied and their derivation, etc.
· Nature of quality control procedures adopted (eg standards, blanks,
duplicates, external laboratory checks) and whether acceptable levels of
accuracy (ie lack of bias) and precision have been established.
Verification of sampling and assaying · The verification of significant intersections by either independent · Not applicable - no drilling is reported
or alternative company personnel.
· The use of twinned holes.
· Documentation of primary data, data entry procedures, data
verification, data storage (physical and electronic) protocols.
· Discuss any adjustment to assay data.
Location of data points · Accuracy and quality of surveys used to locate drill holes (collar · All image and data were recorded and stored in GDA94 MGA53
and down-hole surveys), trenches, mine workings and other locations used in
Mineral Resource estimation.
· Specification of the grid system used.
· Quality and adequacy of topographic control.
Data spacing and distribution · Data spacing for reporting of Exploration Results. · The CSAMT survey was conducted across nine lines of 1400m with
200m spacing in between. Station spacing was 25m along each line for a total
· Whether the data spacing and distribution is sufficient to establish of 504 stations and a total line length of 12.6km
the degree of geological and grade continuity appropriate for the Mineral
Resource and Ore Reserve estimation procedure(s) and classifications applied.
· Whether sample compositing has been applied.
Orientation of data in relation to geological structure · Whether the orientation of sampling achieves unbiased sampling of · Lines were run SW-NE in orientation to best defined the primary
possible structures and the extent to which this is known, considering the structural orientations defined at the Clarke prospect.
deposit type.
· If the relationship between the drilling orientation and the
orientation of key mineralised structures is considered to have introduced a
sampling bias, this should be assessed and reported if material.
Sample security · The measures taken to ensure sample security. · Stacked datasets were downloaded daily from the Loupe instrument
and sent to SGC for review of data quality and for safe storage of data.
Audits or reviews · The results of any audits or reviews of sampling techniques and data. · No audits or reviews have been completed.
Section 2 Reporting of Exploration Results
(Criteria listed in the preceding section also apply to this section.)
Criteria JORC Code explanation Commentary
Mineral tenement and land tenure status · Type, reference name/number, location and ownership including · This geophysical program has been carried out on EL 6131,
agreements or material issues with third parties such as joint ventures, currently owned 100% by Peninsula Resources limited, a wholly owned subsidiary
partnerships, overriding royalties, native title interests, historical sites, of Andromeda Metals Limited.
wilderness or national park and environmental settings.
· Alcrest Royalties Australia Pty Ltd retains a 1.5% NSR royalty
· The security of the tenure held at the time of reporting along with over future mineral production from both licences.
any known impediments to obtaining a licence to operate in the area.
· Baggy Green, Clarke, Laker & the IOCG targets are located
within Pinkawillinnie Conservation Park. Native Title Agreement has been
negotiated with the NT Claimant and has been registered with the SA
Government.
· Aboriginal heritage surveys have been completed over the Baggy
Green project area, with no sites located in the immediate vicinity.
· A Native Title Agreement is in place with the relevant Native
Title party.
Exploration done by other parties · Acknowledgment and appraisal of exploration by other parties. • On-ground exploration completed prior to Andromeda Metals' work
was limited to 400 m spaced soil geochemistry completed by Newcrest Mining
Limited over the Barns prospect.
· Other than the flying of regional airborne geophysics and coarse
spaced ground gravity, there has been no recorded exploration in the vicinity
of the Baggy Green deposit prior to Andromeda Metals' work.
Geology · Deposit type, geological setting and style of mineralisation. · The deposits are either lode gold or intrusion type
mineralisation related to the 1590 Ma Hiltaba/ GRV tectonothermal event.
· Gold mineralisation has a spatial association with mafic
intrusions/ granodiorite alteration and is associated with metasomatic
alteration of host rocks.
· Rare earth minerals occur within the kaolinised saprolite
horizon. Preliminary work supports Ion Adsorbed Clay ("IAC") mineralisation.
· XRF, Hylogger spectral analysis, SEM and preliminary
metallurgical testing demonstrate a change in mineral phase from basement to
lower saprock. Elevated REE grades within saprolite have low occurrences of
identifiable REE bearing minerals supporting that a component of the REE
bursary is adsorbed to clay.
· pH testing supports that REE grade and mineral state is a product
of REDOX conditions with elevated REE grades being associated with conditions
pH6-7 and pH 9.5-10.5.
· Further work is planned to define mineralogy and nature of
mineral occurrence.
· A summary of all information material to the understanding of the · Not applicable - no drilling is reported
exploration results including a tabulation of the following information for
all Material drill holes:
o easting and northing of the drill hole collar
o elevation or RL (Reduced Level - elevation above sea level in metres) of
the drill hole collar
o dip and azimuth of the hole
o down hole length and interception depth
o hole length.
· If the exclusion of this information is justified on the basis that
the information is not Material and this exclusion does not detract from the
understanding of the report, the Competent Person should clearly explain why
this is the case.
Data aggregation methods · In reporting Exploration Results, weighting averaging techniques, · Not applicable - no drilling is reported
maximum and/or minimum grade truncations (eg cutting of high grades) and
cut-off grades are usually Material and should be stated.
· Where aggregate intercepts incorporate short lengths of high grade
results and longer lengths of low grade results, the procedure used for such
aggregation should be stated and some typical examples of such aggregations
should be shown in detail.
· The assumptions used for any reporting of metal equivalent values
should be clearly stated.
Relationship between mineralisation widths and intercept lengths · These relationships are particularly important in the reporting of · Not applicable - no drilling is reported
Exploration Results.
· If the geometry of the mineralisation with respect to the drill hole
angle is known, its nature should be reported.
· If it is not known and only the down hole lengths are reported, there
should be a clear statement to this effect (eg 'down hole length, true width
not known').
Diagrams · Appropriate maps and sections (with scales) and tabulations of · Plan maps are referenced that demonstrate results of interest.
intercepts should be included for any significant discovery being reported
These should include, but not be limited to a plan view of drill hole collar
locations and appropriate sectional views.
Balanced reporting · Where comprehensive reporting of all Exploration Results is not · The reporting is considered balanced
practicable, representative reporting of both low and high grades and/or
widths should be practiced to avoid misleading reporting of Exploration
Results.
Other substantive exploration data · Other exploration data, if meaningful and material, should be · Previously reported significant Gold and REE mineralization and
reported including (but not limited to): geological observations; geophysical resource areas are shown on associated plans
survey results; geochemical survey results; bulk samples - size and method of
treatment; metallurgical test results; bulk density, groundwater, geotechnical
and rock characteristics; potential deleterious or contaminating substances.
Further work · The nature and scale of planned further work (eg tests for lateral · Further AC and RC drilling is planned to test the new
extensions or depth extensions or large-scale step-out drilling). interpretation from this new data set as outlined on the associated plan maps.
· Diagrams clearly highlighting the areas of possible extensions,
including the main geological interpretations and future drilling areas,
provided this information is not commercially sensitive.
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