REG - Castillo Copper Ltd - Update on BHA Project
15/02/2022 07:00
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RNS Number : 6533B Castillo Copper Limited 15 February 2022
15 February 2022
CASTILLO COPPER LIMITED
("Castillo" or the "Company")
Update on BHA Project
Shallow cobalt mineralisation zones identified as development work
accelerates
Castillo Copper Limited (LSE and ASX: CCZ), a base metal explorer primarily
focused on copper across Australia and Zambia, is pleased to announce that
work on codifying legacy assayed drill-hole data at the BHA Project's East
Zone has exceeded 70% (out of 6,182 drill-holes(1)). Pleasingly, this should
enable work on potentially geologically modelling a JORC 2012 compliant
mineral resource estimate ("MRE") focused on cobalt with the potential for
base metal credits, to commence shortly. In addition, the geology team
delineated the area to be modelled which is 2.5km long by 600m wide and
located in the south-east quadrant.
Highlights
· Preliminary interpretations, based on analysing assayed drill-hole
data, suggests cobalt mineralisation, with coincident base metal occurrences,
is within four zones down to a relatively shallow 70m
· Over 70% of 6,182 drill-holes(1) are now coded, which should enable
work on modelling a JORC 2012 compliant MRE focused on cobalt with potential
for base metal credits, to commence shortly
· The ability to leverage legacy data to potentially model a JORC 2012
MRE is a win-win, as it can fast-track developing the BHA Project at a
negligible cost and create material value for shareholders
Dr Dennis Jensen, CEO of Castillo Copper, commented: "Preliminary
interpretations from analysing assayed drillhole data collected so far
suggests cobalt mineralisation is within four zones down to a relative shallow
70m, with coincident base metal occurrences. This is encouraging as our
geology team have now coded over 70% of the 6,182 drill-holes within the BHA
Project's East Zone and will shortly commence modelling a JORC 2012 compliant
inferred mineral resource estimate focused on cobalt with potential for base
and precious metal credits. In addition, the target area to be modelled is
2.5km long by 600m wide and located in the tenure's south-east quadrant. In
the Board's view, uncovering and leveraging high-quality legacy assays to
potentially model up a JORC 2012 compliant MRE can materially advance the East
Zone and create value for shareholders."
SHALLOW COBALT MINERALISATION
A closer examination of some of the drill-holes processed to date suggests
that cobalt mineralisation occurs in four zones, mostly down to 70m, within
certain parts of the target area.
One line at the historical North Broken Hill's Quartz Reef Prospect (Line 1800
E) was drilled across a steeply dipping gossanous quartz magnetite and quartz
pyrite(1). A well-defined zone of quartz magnetite, quartz pyrite and
amphibolite with anomalous geochemistry returning 200 ppm to 2,500ppm Co
occurs in the Redan Gneiss. Thin bands of 0.10% to 0.21% Cu (1,000 to
2,100ppm) occur in these broadly anomalous zones, while lead values are low
(<50 ppm) and zinc rarely exceeds 100 ppm(1).
Elsewhere in the tenure cobalt is seldom greater than 100 ppm, but can be
anomalous in limonitic manganiferous Redan Gneiss, with 1m @ 0.25% and 3m @
900 ppm Co in hole 1180 N, and 3m @ 950 ppm Co in hole 1200N. Generally,
nickel follows the cobalt trend, having values up to 800 ppm(1).
Once the full data set is coded, which is currently being fast tracked, work
will commence on modelling a JORC 2012 compliant MRE focused on cobalt with
potential for base metal credits.
The Board believes utilising legacy assayed drill-hole data to potentially
model a JORC 2012 compliant MRE delivers Castillo a significant comparative
advantage over peers in the Broken Hill region. Notably, the direct geological
modelling costs are negligible relative to undertaking multi-year integrated
drilling campaigns to generate the same result.
Next steps
In NSW:
· JORC 2012 compliant mineral resource estimate for the BHA
Project's East Zone.
In Queensland:
· Assay results for the Arya Prospect; and
· Big One Deposit - JORC 2012 compliant mineral resource
estimate.
In Zambia:
· Complete geophysical report on the Mkushi Project; and
· Complete work on the inaugural drilling campaign for the
Luanshya Project.
In addition to this release, a PDF version with supplementary information and
images can be found on the Company's website:
https://castillocopper.com/investors/announcements/
(https://castillocopper.com/investors/announcements/)
For further information, please contact:
Castillo Copper Limited +61 8 6558 0886
Dr Dennis Jensen (Australia), Chief Executive Officer
Gerrard Hall (UK), Director
SI Capital Limited (Financial Adviser and Corporate Broker) +44 (0)1483 413500
Nick Emerson
Luther Pendragon (Financial PR) +44 (0)20 7618 9100
Harry Chathli, Alexis Gore
About Castillo Copper
Castillo Copper Limited is an Australian-based explorer primarily focused on
copper across Australia and Zambia. The group is embarking on a strategic
transformation to morph into a mid-tier copper group underpinned by its core
projects:
· A large footprint in the Mt Isa copper-belt district, north-west
Queensland, which delivers significant exploration upside through having
several high-grade targets and a sizeable untested anomaly within its
boundaries in a copper-rich region.
· Four high-quality prospective assets across Zambia's copper-belt
which is the second largest copper producer in Africa.
· A large tenure footprint proximal to Broken Hill's world-class
deposit that is prospective for zinc-silver-lead-copper-gold.
· Cangai Copper Mine in northern New South Wales, which is one of
Australia's highest grading historic copper mines.
The group is listed on the LSE and ASX under the ticker "CCZ."
References
1) CCZ ASX Release - 9 February, Leyh W.R., 1977
Progress Report on Farmcote Exploration Licenses 780 and 782, Farmcote Area,
Broken Hill, NSW for the three months to 27 October 1978, North Broken Hill
Limited for the NSW Geological Survey, (GS1977-078) and Leyh W.R., 1978
Progress Report on Exploration Licenses 1099 and 1100 for the six months to 27
October 1978, North Broken Hill Limited for the NSW Geological Survey,
(GS1978-407)
Competent Person Statement
The information in this report that relates to Exploration Results for "BHA
Project, East Zone" is based on information compiled or reviewed by Mr Mark
Biggs. Mr Biggs is a director of ROM Resources, a company which is a
shareholder of Castillo Copper Limited. ROM Resources provides ad hoc
geological consultancy services to Castillo Copper Limited. Mr Biggs is a
member of the Australian Institute of Mining and Metallurgy (member #107188)
and has sufficient experience of relevance to the styles of mineralisation and
types of deposits under consideration, and to the activities undertaken, to
qualify as a Competent Person as defined in the 2012 Edition of the Joint Ore
Reserves Committee (JORC) Australasian Code for Reporting of Exploration
Results, and Mineral Resources. Mr Biggs holds an AusIMM Online Course
Certificate in 2012 JORC Code Reporting. Mr Biggs also consents to the
inclusion in this report of the matters based on information in the form and
context in which it appears.
APPENDIX: JORC CODE, 2012 EDITION - TABLE 1
(Criteria in this section apply to all succeeding sections.)
Criteria JORC Code explanation Commentary
Sampling techniques · Nature and quality of sampling (e.g., cut channels, random chips, or · Sampling used in this analysis was all historical from the period
specific specialised industry standard measurement tools appropriate to the 1964-2018. This includes the 2016 and 2018 Squadron Resources soil sampling
minerals under investigation, such as down hole gamma sondes, or handheld XRF program. The data was a combination of the NSW Geological Survey surface
instruments, etc.). These examples should not be taken as limiting the broad sampling database and historical annual and relinquishment reports revisited
meaning of sampling. and additional data extracted.
· Include reference to measures taken to ensure sample representivity · Sampling was databased if it occurred inside the EL and in a 300m
and the appropriate calibration of any measurement tools or systems used. buffer surrounding the EL, to establish anomalous trend directions, if any
existed.
· Aspects of the determination of mineralisation that are Material to
the Public Report. · Nearly 6,555 sample analyses from stream sediment, soil, and rock
chip sources were collated and combined. Of these approximately 680 sample
· In cases where 'industry standard' work has been done this would be did not reside in the government database and had to be encoded or
relatively simple (e.g., 'reverse circulation drilling was used to obtain 1 m georeferenced from the source reports (12 in total).
samples from which 3 kg was pulverised to produce a 30g charge for fire
assay'). In other cases, more explanation may be required, such as where there · Reference to these reports is given in the associated geology report
is coarse gold that has inherent sampling problems. Unusual commodities or (Biggs (2021a).
mineralisation types (eg submarine nodules) may warrant disclosure of detailed
information. · Many of the sampling programs, especially from the 1990's did include
reference samples and duplicate analyses and other forms of QA/QC checking.
· Sampling prior to 1988 generally has higher "below detection limits"
and less or no QA/QC checks.
Drilling techniques · Drill type (e.g. core, reverse circulation, open-hole hammer, rotary · Historical drilling consists of auger, rotary air blast, reverse
air blast, auger, Bangka, sonic, etc.) and details (e.g. core diameter, triple circulation and diamond coring. In and around the model area are 6,182
or standard tube, depth of diamond tails, face-sampling bit or other type, drillholes, however it should be noted that the majority of these are <18m
whether core is oriented and if so, by what method, etc.). in depth, and the number of holes >100m number around 14. Complete
drilling analyses results are in the process of being compiled, and hence did
not form part of this study.
Drill sample recovery · Method of recording and assessing core and chip sample recoveries and · Not applicable in this study, no new holes completed.
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 · The drilling that did occur was generally completed to modern-day
geotechnically logged to a level of detail to support appropriate Mineral standards. The preferred exploration strategy in the eighties and early
Resource estimation, mining studies and metallurgical studies. nineties was to drill shallow auger holes to negate the influence of any
Quaternary and Tertiary thin cover.
· Whether logging is qualitative or quantitative in nature. Core (or
costean, channel, etc) photography. · No downhole geophysical logging took place.
· 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, as no new drilling was undertaken.
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 · All of the analyses bar a few (<500 out 11,975) samples were
laboratory procedures used and whether the technique is considered partial or laboratory tested in various NATA-registered laboratories throughout
total. Australia. Many of the earlier CRA Exploration stream sediment and soil
samples were analysed by CRA internal laboratories. North Broken Hill used
· For geophysical tools, spectrometers, handheld XRF instruments, etc, their onsite laboratory on some campaigns.
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 (i.e. lack of bias) and precision have been established.
Verification of sampling and assaying · The verification of significant intersections by either independent · Over 830 samples have had their assays duplicated.
or alternative company personnel.
· None of the historical data has been adjusted.
· 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 · In general, locational accuracy does vary, depending upon whether the
and down-hole surveys), trenches, mine workings and other locations used in samples were digitised off plans or had their coordinated tabulated. Many
Mineral Resource estimation. samples were reported to AGD66 or AMG84 and have been converted to MGA94.Zone
54
· Specification of the grid system used.
· It is estimated that locational accuracy therefor varies between
· Quality and adequacy of topographic control. 2-50m
Data spacing and distribution · Data spacing for reporting of Exploration Results. · The average sample spacing across the tenure varies per element, and
sample type, as listed in Table A3-1-1, below:
· Whether the data spacing and distribution is sufficient to establish
Table A3-1: EL 8434 and EL 8435 Surface and Drillhole Sampling
the degree of geological and grade continuity appropriate for the Mineral Description Number Average Spacing Comments
Resource and Ore Reserve estimation procedure(s) and classifications applied. Stream Sediment 1,395 320 Includes BCL
Soil 1,049 240
· Whether sample compositing has been applied. Surface Rock Chip 2,150 185
Drilling 11,975 220 Includes shallow auger holes. Six (6) holes in the tenures are held in GSNSW
library.
Mineral Occurrences 98 420 Includes quarries and industrial minerals occurrences
· No sample compositing has been applied.
Orientation of data in relation to geological structure · Whether the orientation of sampling achieves unbiased sampling of · The current database does not contain any sub-surface geological
possible structures and the extent to which this is known, considering the logging, which is being compiled (70% complete)
deposit type.
· Geological mapping by various companies has reinforced that the
· If the relationship between the drilling orientation and the strata dips variously between 40 and 83 degrees.
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. · The sample security measures, except for the Squadron Resources work
programs is not known. Squadron took samples to their Broken Hill office and
transported samples for analysis to ALS Broken Hill
Audits or reviews · The results of any audits or reviews of sampling techniques and data. · No audits or reviews have yet been undertaken.
· No sample compositing has been applied.
Orientation of data in relation to geological structure
· Whether the orientation of sampling achieves unbiased sampling of
possible structures and the extent to which this is known, considering the
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.
· The current database does not contain any sub-surface geological
logging, which is being compiled (70% complete)
· Geological mapping by various companies has reinforced that the
strata dips variously between 40 and 83 degrees.
Sample security
· The measures taken to ensure sample security.
· The sample security measures, except for the Squadron Resources work
programs is not known. Squadron took samples to their Broken Hill office and
transported samples for analysis to ALS Broken Hill
Audits or reviews
· The results of any audits or reviews of sampling techniques and data.
· No audits or reviews have yet been undertaken.
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 EL 8434 is located about 28km east of Broken Hill whilst EL 8435 is 16km east
agreements or material issues with third parties such as joint ventures, of Broken Hill. Both tenures are approximately 900km northwest of Sydney in
partnerships, overriding royalties, native title interests, historical sites, far western New South Wales (Figure A12-1).
wilderness or national park and environmental settings.
EL 8434 and EL 8435 were both granted on the 2(nd of) June 2016 to Squadron
· The security of the tenure held at the time of reporting along with Resources for a term of five (5) years for Group One Minerals. On the 25(th
any known impediments to obtaining a licence to operate in the area. of) May 2020, Squadron Resources changed its name to Wyloo Metals Pty Ltd
(Wyloo). In December 2020 the tenure was transferred from Wyloo Metals to
Broken Hill Alliance Pty Ltd a 100% subsidiary company of Castillo Copper
Limited. Both tenures were renewed on the 12(th of) August 2021 for a
further six (6) years and are due to expire on the 2(nd of) June 2027.
EL 8434 lies across two (2) 1:100,000 geology map sheets Redan 7233 and
Taltingan 7234, and two (2) 1:250,000 geology map sheets, SI54-3 Menindee and
SH54-15 Broken Hill in the county of Yancowinna. EL 8434 consists of one
hundred and eighty-six (186) units) in the Adelaide and Broken Hill
1:1,000,000 Blocks covering an area of approximately 580km(2).
EL 8435 is located on the 1:100,000 geology map sheet Taltingan 7234, and the
1:250,000 geology map sheet SH/54-15 Broken Hill in the county of
Yancowinna. EL 8435 consists of twenty-two (22) units (Table 1) in the
Broken Hill 1:1,000,000 Blocks covering an area of approximately 68km(2).
Access to the tenures from Broken Hill is via the sealed Barrier Highway.
This road runs north-east to south-west through the northern portion of the EL
8434, passes the southern tip of EL 8435 eastern section and through the
middle of the western section of EL 8435. Access is also available via the
Menindee Road which runs north-west to south-east through the southern section
of the EL 8434. The Orange to Broken Hill Rail line also dissects EL 8435
western section the middle and then travels north-west to south-east slicing
through the eastern arm of EL 8434 (Figure A3-2-1).
Figure A3-2-1: EL 8434 and EL 8434 General Location Map
(Available to view on ASX announcement at: https://castillocopper.com/investors/announcements/)
Exploration done by other parties · Acknowledgment and appraisal of exploration by other parties. Explorers who were actively involved over longer historical periods in various
parts of EL8434 were: - North Broken Hill Ltd, CRAE Exploration, Major Mining
Ltd and Broken Hill Metals NL, Pasminco Exploration Ltd, Normandy Exploration
Ltd, PlatSearch NL/Inco Ltd/ EGC Pty Ltd JV and the Western Plains Gold
Ltd/PlatSearch/EGC Pty Ltd JV.
A comprehensive summary of work by previous explorers was presented in Leyh
(2009). However, more recently, follow-up field reconnaissance of areas of
geological interest, including most of the prospective zones was carried out
by EGC Pty Ltd over the various licenses. This work, in conjunction with a
detailed interpretation of aeromagnetic, gravity plus RAB / RC drill hole
logging originally led to the identification of at least sixteen higher
priority prospect areas. All these prospects were summarized in considerable
detail in Leyh (2008). Future work programs were then also proposed for each
area. Since then, further compilation work plus detailed geological
reconnaissance mapping and sampling of gossans and lode rocks has been carried
out.
A total of 22 prospects were then recognised on the exploration licence with
at least 12 occurring in and around the tenure.
With less than 15% outcropping Proterozoic terrain within the licence, this
makes it very difficult to explore and is in the main very effectively
screened from the easy application of more conventional exploration
methodologies due to a predominance of extensive Cainozoic cover sequences.
These include recent to young Quaternary soils, sands, clays and older more
resistant, only partially dissected, Tertiary duricrust regolith covered
areas. Depth of cover ranges from a few metres in the north to over 60
metres in some areas on the southern and central license.
Exploration by EGC Pty Ltd carried out in the field in the first instance has
therefore been heavily reliant upon time consuming systematic geological
reconnaissance mapping and relatable geochemical sampling. These involve a
slow systematic search over low outcropping areas, poorly exposed subcrops and
float areas as well as the progressive development of effective regolith
mapping and sampling tools. This work has been combined with a vast amount
of intermittently acquired past exploration data. The recent data
compilation includes an insufficiently detailed NSWGS regional mapping scale
given the problems involved, plus some regionally extensive, highly variable,
low-level stream and soil BLEG geochemical data sets over much of the area.
There are also a few useful local detailed mapping grids at the higher
priority prospects, and many more numerous widespread regional augers, RAB and
percussion grid drilling data sets. Geophysical data sets including ground
magnetics, IP and EM over some prospect areas have also been integrated into
the exploration models. These are located mainly in former areas of moderate
interest and most of the electrical survey methods to date in this type of
terrain continue to be of limited application due to the high degree of
weathering and the often prevailing and complex regolith cover constraints.
Between 2007 and 2014 Eaglehawk Geological Consulting has carried out detailed
research, plus compilation and interpretation of a very large volume of
historic exploration data sourced from numerous previous explorers and dating
back to the early 1970's. Most of this data is in non-digital scanned form.
Many hard copy exploration reports (see references) plus several hundred plans
have been acquired from various sources, hard copy printed as well as
downloaded as scans from the Geological Survey of NSW DIGS system. They also
conducted field mapping, costean mapping and sampling, and rock chip sampling
and analysis.
Work Carried out by Squadron Resources and Whyloo Metals 2016-2020
Research during Year 1 by Squadron Resources revealed that the PGE-rich,
sulphide-bearing ultramafic rocks in the Broken Hill region have a
demonstrably alkaline affinity. This indicates a poor prospectivity for
economic accumulations of sulphide on an empirical basis (e.g., in comparison
to all known economic magmatic nickel sulphide deposits, which have a
dominantly tholeiitic affinity). Squadron instead directed efforts toward
detecting new Broken Hill-Type (BHT) deposits that are synchronous with basin
formation. Supporting this modified exploration rationale are the EL's
stratigraphic position, proximity to the Broken Hill line of lode, abundant
mapped alteration (e.g., gahnite and/or garnet bearing exhalative units) and
known occurrences such as the "Sisters" and "Iron Blow" prospects.
The area overlies a potential magmatic Ni-Cu-PGE source region of
metasomatised sub-continental lithospheric mantle (SCLM) identified from a
regional targeting geophysical data base. The exploration model at the time
proposed involved remobilization of Ni-Cu-PGE in SCLM and incorporation into
low degree mafic-ultramafic partial melts during a post-Paleoproterozoic plume
event and emplacement higher in the crust as chonoliths/small intrusives -
Voisey's Bay type model. Programs were devised to use geophysics and
geological mapping to locate secondary structures likely to control and
localise emplacement of Ni-Cu-PGE bearing chonoliths. Since EL8434 was
granted, the following has been completed:
• Airborne EM survey.
• Soil and chip sampling.
• Data compilation.
• Geological and logistical reconnaissance.
• Community consultations; and
• Execution of land access agreements.
Airborne EM Survey
Geotech Airborne Limited was engaged to conduct an airborne EM survey using
their proprietary VTEM system in 2017. A total of 648.92-line kilometres
were flown on a nominal 200m line spacing over a portion of the project area.
Several areas were infilled to 100m line spacing.
The VTEM data was interpreted by Southern Geoscience Consultants Pty Ltd, who
identified a series of anomalies, which were classified as high or low
priority based on anomaly strength (i.e., does the anomaly persist into the
latest channels). Additionally, a cluster of VTEM anomalies at the "Sisters"
prospect have been classified separate due to strong IP effects observed in
the data. Geotech Airborne have provided an IP corrected data and
interpretation of the data has since been undertaken.
Soil and Chip sampling
The VTEM anomalies were followed up by a reconnaissance soil sampling
programme. Spatially clustered VTEM anomalies were grouped, and follow-up soil
lines were designed. Two (2) VTEM anomalies were found to be related to
culture and consequently no soils were collected. Two (2) other anomalies
were sampled which were located above thick alluvium of Stephens Creek and
were therefore not sampled. A line of soil samples was collected over a
relatively undisturbed section at Iron Blow workings and the Sisters Prospect.
One hundred and sixty-six (166) soil samples were collected at a nominal 20cm
depth using a 2mm aluminium sieve. Two (2) rock chips were also collected
during this program. The samples were collected at either 20m or 40m spacing
over selected VTEM anomalies. The samples were pulverised and analysed by
portal XRF at ALS laboratories in Perth.
Each site was annotated with a "Regolith Regime" such that samples from a
depositional environment could be distinguished from those on exposed
Proterozoic bedrock, which were classified as an erosional environment. The
Regolith Regime groups were used for statistical analysis and levelling of the
results. The levelled data reveals strong relative anomalies in zinc at VTEM
anomaly clusters 10, 12 and 14 plus strong anomalous copper at VTEM 17.
Geology · Deposit type, geological setting, and style of mineralisation. Regional Geology
The Broken Hill polymetallic deposits are located within Curnamona Province
(Willyama Super group) (Figure A3-2-2) that hosts several world-class deposits
of lead, zinc, silver, and copper. The Willyama Supergroup consists of
highly deformed metasedimentary schists and gneisses with abundant
quartz-feldspathic gneisses, lesser basic gneisses, and minor 'lode' rocks
which are quartz-albite and calc-silicate rocks (Geoscience Australia,
2019). Prograde metamorphism ranges from andalusite through sillimanite to
granulite grade (Stevens, Barnes, Brown, Stroud, & Willis, 1988).
Regionally, the tenures are situated in Broken Hill spatial domain which
extends from far western New South Wales into eastern South Australia. The
Broken Hill Domain hosts several major fault systems and shear zones, which
were formed by various deformation events and widespread metamorphism which
has affected the Willyama Supergroup (Figure A3-2-3). Major faults in the
region include the Mundi Mundi Fault to the west of Broken Hill, the Mulculca
Fault to the east, and the Redan Fault to the south. Broken Hill is also
surrounded by extensive shear zones including the Stephens Creek,
Globe-Vauxhall, Rupee, Pine Creek, Albert, and Thackaringa-Pinnacles Shear
Zones.
Figure A3-2-2: Regional Stratigraphy (Available to view on ASX announcement at:
https://castillocopper.com/investors/announcements/ (https://castillocopper.com/investors/announcements/)
)
Figure A3-2-3: Regional Geological Map (Available to view on ASX
announcement at: https://castillocopper.com/investors/announcements/
(https://castillocopper.com/investors/announcements/) )
There are over twenty (20) rock formations mapped within the project area.
Parts of the project area are covered by Quaternary alluvium, sands, and by
Tertiary laterite obscuring the basement geology. Within the Lower to Middle
Proterozoic Willyama Supergroup (previously Complex) there are two (2) groups,
the Thackaringa Group, and the younger Broken Hill Group (Colquhoun, et al.,
2019).
Local Geology
A summary of the units that host or appear to host the various mineralisation
styles within EL 8434 and EL 8435 is given below.
Broken Hill Group
The Hores Gneiss is mostly comprised of quartz-feldspar-biotite-garnet gneiss,
interpreted as metadacite with some minor metasediments noted. An age range
from Zircon dating has been reported as 1682-1695Ma (Geoscience Australia,
2019). The Allendale Metasediments unit contains mostly metasedimentary
rocks, dominated by albitic, pelitic to psammitic composite gneiss, including
garnet-bearing feldspathic composite gneiss, sporadic basic gneiss, and
quartz-gahnite rock. Calc-silicate bodies can be found at the base of the
unit and the formation's average age is 1691 Ma (Geoscience Australia, 2019).
Thackaringa Group
The Thorndale Composite Gneiss is distinguished by mostly gneiss, but also
migmatite, amphibolite, and minor magnetite. The age of this unit is
>1700Ma (Geoscience Australia, 2019) and is one of the oldest formations in
the Group. The Cues Formation is interpreted as a deformed sill-like
granite, including Potosi-type gneiss. Other rock-types include pelitic
paragneiss, containing cordierite. The average age: ca 1700-1730 Ma.
(Stevens, Barnes, Brown, Stroud, & Willis, 1988). Other rock types
include mainly psammo-pelitic to psammitic composite gneisses or
metasedimentary rocks, and intercalated bodies of basic gneiss. This unit is
characterised by stratiform horizons of granular garnet-quartz +/-magnetite
rocks, quartz-iron oxide/sulphide rocks and quartz-magnetite rocks (Geoscience
Australia, 2019). This is a significant formation as it hosts the Pinnacles
Ag-Pb-Zn massive sulphide deposit along with widespread Fe-rich stratiform
horizons. The protolith was probably sandy marine shelf sedimentary rocks.
An intrusion under shallow cover was syn-depositional. The contained
leuco-gneisses and Potosi-type gneisses are believed to represent a felsic
volcanic or volcaniclastic protolith. Basic gneisses occur in a substantial
continuous interval in the middle sections of the Formation, underlain by
thinner, less continuous bodies. They are moderately Fe-rich (abundant
orthopyroxene or garnet) and finely layered, in places with pale feldspar-rich
layers, and are associated with medium-grained quartz-feldspar-biotite-garnet
gneiss or rock which occurs in thin bodies or pods ('Potosi-type' gneiss). A
distinctive leucocratic quartz-microcline-albite(-garnet) gneiss (interpreted
as meta-rhyolite) occurs as thin, continuous, and extensive horizons, in
several areas. The sulphide-bearing rocks may be lateral equivalents of, or
associates of Broken Hill type stratiform mineralisation. Minor layered
garnet-epidote-quartz calc-silicate rocks occur locally within the middle to
basal section. The unit is overlain by the Himalaya Formation. The Cues
Formation is intruded by Alma Granite (Geoscience Australia, 2019). The
Himalaya Formation (Figure A3-2-4) consists of medium-grained saccharoidal
leucocratic psammitic and albitic meta-sedimentary rocks (average age
1700Ma). The unit comprises variably interbedded albite-quartz rich rocks,
composite gneiss, basic gneiss, horizons of thinly bedded quartz-magnetite
rock. Pyrite-rich rocks occur at the base of the formation (Geoscience
Australia, 2019). It is overlain by the Allendale Metasediments (Broken Hill
Group). The Himalaya Formation hosts cobalt-rich pyritic horizons at Pyrite
Hill and Big Hill. The protolith is probably sandy marine shelf sedimentary
rocks with variable evaporitic or hypersaline component. Plagioclase-quartz
rocks are well-bedded (beds 20 - 30mm thick), with rare scour-and-fill and
cross-bedded structures. Thin to thick (0.5 - 10m) horizons of thinly bedded
quartz-magnetite rock also occur with the plagioclase-quartz rocks. In some
areas the formation consists of thin interbeds of plagioclase-quartz rocks
within meta-sedimentary rocks or metasedimentary composite gneiss (Geoscience
Australia, 2019). Lady Brassey Formation which is well-to-poorly-bedded
leucocratic sodic plagioclase-quartz rock, as massive units or as thick to
thin interbeds within psammitic to pelitic metasedimentary composite
gneisses. A substantial conformable basic gneiss. It overlies both
Mulculca Formation and Thorndale Composite Gneiss. Part of the formation was
formerly referred to as Farmcote Gneiss in the Redan geophysical zone of
Broken Hill Domain - a zone in which the stratigraphy has been revised to
create the new Rantyga Group (Redan and Ednas Gneisses, Mulculca Formation,
and the now formalised Farmcote Gneiss).
Lady Louise Suite
This unit is approximately 1.69Ma in age comprising amphibolite,
quartz-bearing, locally differentiated to hornblende granite, intrusive sills,
and dykes, metamorphosed, and deformed; metabasalt with pillows (Geoscience
Australia, 2019). Annadale Metadolerite is basic gneisses, which includes
intervening metasedimentary rocks possibly dolerite (Geoscience Australia,
2021).
Rantya Group
Farmcote Gneiss contains metasediments and gneiss and is a new unit at the top
of Rantyga Group. It is overlain by the Cues Formation and Thackaringa
Group, and it overlies the Mulculca Formation. The age of the unit is
between 1602 to 1710Ma. Mulculca Formation is abundant metasedimentary
composite gneiss, variable sodic plagioclase-quartz-magnetite rock,
quartz-albite-magnetite gneiss, minor quartz-magnetite rock common, minor
basic gneiss, albite-hornblende-quartz rock (Geoscience Australia, 2019).
Ednas Gneiss contains quartz-albite-magnetite gneiss, sodic
plagioclase-quartz-magnetite rock, minor albite-hornblende-quartz rock, minor
quartzo-feldspathic composite gneiss. It is overlain by Mulculca Formation.
Silver City Suite
Formerly mapped in the Thackaringa Group this new grouping accommodates the
metamorphosed and deformed granites. A metagranite containing
quartz-feldspar-biotite gneiss with variable garnet, sillimanite, and
muscovite, even-grained to megacrystic, elongate parallel to enclosing
stratigraphy. It occurs as sills and intrudes both the Thackeringa Group and
the Broken Hill Group. This unit is aged between 1680 to 1707Ma.
Torrowangee Group
Mulcatcha Formation comprises flaggy, quartzose sandstone with lenticular
boulder and arkosic sandstone beds. Yangalla Formation contains boulder
beds, lenticular interbedded siltstone, and sandstone. It overlies the
Mulcatcha Formation (Geoscience Australia, 2020).
Sundown Group
The Sundown Group contains Interbedded pelite, psammopelitic and psammitic
metasedimentary rocks and it overlies the Broken Hill Group. The unit age is
from 1665 to 1692Ma.
There is also an unnamed amphibolite in Willyama Supergroup, which present
typically medium grained plagioclase and amphibole or pyroxene rich stratiform
or discordant dykes.
Figure A3-2-4: EL 8434 and EL 8435 Solid Geology (Available to view on ASX announcement at:
https://castillocopper.com/investors/announcements/ (https://castillocopper.com/investors/announcements/)
)
Drill hole Information · A summary of all information material to the understanding of the · No new drillholes have been completed yet.
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, · No new assays are reported in this announcement
maximum and/or minimum grade truncations (e.g., 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 · As a database of all the historical borehole sampling has not yet
Exploration Results. been compiled and validated (in progress) it is uncertain if there is a
relationship between the surface sample anomalies to any subsurface anomalous
· If the geometry of the mineralisation with respect to the drill hole intersections. Mineralisation is commonly associated with shears, faults,
angle is known, its nature should be reported. and pegmatitic intrusions within the shears, or on or adjacent to the
boundaries of the Himalaya Formation.
· If it is not known and only the down hole lengths are reported, there
should be a clear statement to this effect (e.g. 'down hole length, true width · No existing geological 3D models exist but preliminary
not known'). investigation has shown that sufficient data may be available to generate a
small resource of cobalt or zinc.
Diagrams · Appropriate maps and sections (with scales) and tabulations of · Current surface anomalies are shown on maps in the report. All
intercepts should be included for any significant discovery being reported historical surface sampling has had their coordinates converted to MGA94, Zone
These should include, but not be limited to a plan view of drill hole collar 54.
locations and appropriate sectional views.
Balanced reporting · Where comprehensive reporting of all Exploration Results is not · No new exploration results have been reported, but regarding the
practicable, representative reporting of both low and high grades and/or surface sampling, no results other than duplicates, blanks or reference
widths should be practiced to avoid misleading reporting of Exploration standard assays have been omitted.
Results.
Other substantive exploration data · Other exploration data, if meaningful and material, should be · Historical explorers have also conducted airborne and ground gravity,
reported including (but not limited to): geological observations; geophysical magnetic, EM, and IP resistivity surveys over parts of the tenure area but
survey results; geochemical survey results; bulk samples - size and method of this is yet to be collated.
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 (e.g., tests for lateral Work has commenced on Stage 2, which is to identify more anomalies and
extensions or depth extensions or large-scale step-out drilling). priority zones within the EL 8434 and EL8435, it is recommended that:
· Diagrams clearly highlighting the areas of possible extensions, · The non-sampled zone in the centre of the tenure be defined and
including the main geological interpretations and future drilling areas, sampled.
provided this information is not commercially sensitive.
· A more detailed study of historical drillholes should be
conducted to determine if enough data exists to estimate a JORC resource; and
· A program of field mapping and ground magnetic or EM surveys be
planned and executed.
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