- Title:
Potential mineralisation extended at Big One - Time:
07:00:09 - Date:
20 May 2021 - Category:
Corporate updates - ID:
2182Z
CASTILLO COPPER LIMITED
("Castillo" or the "Company")
Geophysics survey extends potential mineralisation and identifies new targets at Big One Deposit
Targets include a significant untested bedrock conductor that is materially larger than the high-grade anomaly drilled in 2020
Castillo Copper Limited (LSE and ASX: CCZ), a base metal explorer primarily focused on copper across Australia and Zambia, is pleased to announce that preliminary interpretations of the inaugural IP survey at the Big One Deposit have identified multiple new prospective anomalies along line of lode, including a significant untested bedrock conductor to the north.
Highlights
· Increased the potential structural targets across the Big One Deposit - compelling evidence that significant incremental mineralisation is located along fault structures rather than constrained within the trachyte dyke
· Findings from Line 3 - which is 700m long (Figure 1) - highlight a significant untested bedrock conductor north of the line of lode that is materially larger than the high-grade anomaly drilled in 2020
· Further, three more untested prospective anomalies along Line 3 were discovered south of the line of lode which collectively bolster the Big One Deposit's exploration potential
· Reconciling the IP survey results with all legacy drilling has boosted the geology team's understanding of the system apparent at the Big One Deposit:
o Several drill holes need to be extended to deeper depths to enhance the probability of intersecting underlying copper mineralisation; and
o New locations and orientations are being made to the next phase of the drilling campaign - which is due to commence shortly - in order to achieve optimal results
Figure 1: Line 3 - Newly Identified Bedrock Conductors - refer to link above
Simon Paull, Managing Director of Castillo Copper, said: "We are very excited by these geophysics results, which significantly enhance the exploration potential of the Big One Deposit. The IP survey provides compelling evidence that known mineralisation extends beyond the line of lode both to the north and to the south. This includes an untested bedrock conductor that is significantly larger than the high-grade anomaly we drilled in 2020. We now have several new high-priority structural targets for the next phase of drill testing which is set to commence shortly."
Geophysics Campaign
The recent IP survey comprised six lines, ranging from 500-700m long, and spaced nominally 200m apart over the 1,200m line of lode which has been subject to three drilling campaigns over the past five decades (Figure 2 - refer to link above).
The primary objective of the campaign was to identify massive new sulphide bedrock conductors along the strike extent and extend known mineralisation. Further, the geology team wanted geophysical insights into several known yet under-explored nearby anomalies that included previously mapped gossanous outcrops to the north-east of the 2020 drilling campaign and scattered historical surface stream sediment and rock chip sampling.
Figure 2: Line locations transversing Big One Deposit- refer to link above
Encouraging Results
In reviewing the results from the IP survey, Line 3 delivered the most compelling new insights, summarised as follows:
· A significant, untested bedrock conductor was identified circa 200m north of the line of lode where last year's high-grade discovery was located (refer to Figure 1 in link above). Notably, the newly discovered target is materially larger than the anomaly intersected in 2020 which produced the following nearby intercepts (between Lines 2 and 3):
o 303RC: 40m @ 1.64% from (fm) surface incl: 11m @ 4.40% fm 24m, 5m @ 7.34% fm 28m & 1m @ 16.65% fm 29m
o 301RC: 44m @ 1.19% Cu fm surface incl: 14m @ 3.55% fm 27m, 3m @ 10.88% fm 37m & 1m @ 12.6% fm 37m
· In addition, south of the line of lode along Line 3, are three more untested anomalies that build on the Big One Deposit's exploration potential
One of the key value-add insights was reconciling the geophysics findings with all legacy drilling results. This enhanced the geology team's understanding of the underlying system and helped to identify the following:
· It is apparent the mineralisation is dictated by emplacement along structures and not the dyke, as there appears to be significant chargeability anomalies away from the trachyte dyke, following lineaments or structural trends
· Initial observations are that historical drilling in the southern region has not tested areas of elevated chargeability (either too shallow or wrong location)
· Not all chargeable anomalies will reflect mineralisation - typically clays, uneconomic sulphides and some lithologies such as shales can give chargeable responses - but certainly the results from Lines 2 and 3 give some confidence that zones of elevated chargeability in this region are of interest as drill tested anomalies have shown significant copper mineralisation
· The next phase of the drilling campaign, which is due to commence shortly, is being realigned to intersect newly identified targets and bolster the chances of achieving optimal results
Next Steps
There are several concurrent next steps that Castillo's teams are working on:
· The geophysicist consultant will prepare a 3D model of the IP survey findings from the Big One Deposit
· The upcoming drilling campaign will soon be finalised ahead of the team moving to site to commence work
For further information, please contact:
| Castillo Copper Limited |
+61 8 6558 0886 |
| Simon Paull (Australia), Managing Director Gerrard Hall (UK), Director |
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| SI Capital Limited (Financial Adviser and Corporate Broker) |
+44 (0)1483 413500 |
| Nick Emerson |
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| Luther Pendragon (Financial PR) |
+44 (0)20 7618 9100 |
| Harry Chathli, Alexis Gore, Joe Quinlan |
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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:
· The Mt Oxide project 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."
Competent Person Statement
The information in this report that relates to Exploration Results for "Big One Deposit" is based on information compiled or reviewed by Mr Mark Biggs. Mr Biggs is both a shareholder and 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 A: PROSPECTS WITHIN THE MT OXIDE PROJECT
FIGURE A1: MT OXIDE PROJECT - refer to link above
The following JORC Code (2012 Edition) Table 1 is primarily supplied for the provision of explaining the IP Survey at the Big One Deposit.
| Criteria |
JORC Code explanation |
Commentary |
| Sampling techniques |
· Nature and quality of sampling (eg cut channels, random chips, or specific specialised industry standard measurement tools appropriate to the minerals under investigation, such as down hole gamma sondes, or handheld XRF instruments, etc). These examples should not be taken as limiting the broad meaning of sampling. · Include reference to measures taken to ensure sample representivity and the appropriate calibration of any measurement tools or systems used. · Aspects of the determination of mineralisation that are Material to the Public Report. · In cases where 'industry standard' work has been done this would be 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 assay'). In other cases, more explanation may be required, such as where there is coarse gold that has inherent sampling problems. Unusual commodities or mineralisation types (e.g., submarine nodules) may warrant disclosure of detailed information. |
· No additional surface or drilling samples have been collected or assayed as this release talks to the recently completed IP ground geophysical survey. |
| Drilling techniques |
· Drill type (e.g., core, reverse circulation, open-hole hammer, rotary air blast, auger, Bangka, sonic, etc) and details (e.g., 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). |
· No new drilling has taken place. |
| Drill sample recovery |
· Method of recording and assessing core and chip sample recoveries and 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. |
· No drilling nor samples were taken. |
| Logging |
· Whether core and chip samples have been geologically and 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. |
· No logging took place. |
| Sub-sampling techniques and sample preparation |
· If core, whether cut or sawn and whether quarter, half or all core 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. |
· No drilling nor samples were taken. |
| Quality of assay data and laboratory tests |
· The nature, quality and appropriateness of the assaying and 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 (i.e. lack of bias) and precision have been established. |
· Not applicable as no new sampling or assaying took place. |
| Verification of sampling and assaying |
· The verification of significant intersections by either independent 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. |
· Not applicable as no new sampling or assaying took place. |
| Location of data points |
· Accuracy and quality of surveys used to locate drill holes (collar 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. |
· The survey, as originally proposed, consisted of the following IP work (as per the survey plan on the next page; Figure A2-1) six 6 lines each 500m in length with 50m dipoles, totalling 3km. · Fender Geophysics had noted in their quote that the methodology may be changed to Pole-Dipole if it is felt this will give better results. Given the line length and depth of the area of interest (150-200m) Fender planned to extend the transmitter sites out by 4 dipoles on the southeast end of the lines to increase depth penetration at that end. · The spatial location for these holes has been differentially surveyed into MGA94 - Zone 54. Collar heights are to the Australian Height Datum. Figure B1 IP Survey Line Location (refer to link above)
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| Data spacing and distribution |
· Data spacing for reporting of Exploration Results. · Whether the data spacing and distribution is sufficient to establish 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. |
· The scope of works for the survey is given below: o Array: Dipole-Dipole (roll-along) o Receiver Dipole Length: 50 m o Transmitter Dipole Length: 50 m o Domain and Cycle: Time domain - 2 seconds or 0.125 Hz o Line Length: 500 m o Number of Lines: 6 o Line kms: 3.0 km |
| 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. |
· Fender Geophysics (Fender) was contracted to complete a program of Dipole-Dipole array IP survey work for Castillo Copper Limited at the Big One deposit located within Castillo's Mt Oxide Project in the Mt Isa copper belt (EPM 26574), approximately 170km north of Mt Isa (see location map below; Figure A2-2). Most of the interpretation comments have been provided by Ms Kate Nelson of GeoDiscovery. Figure B2 Survey General Location (refer to link above)
· The core objectives of the survey were to identify massive sulphide bedrock conductors along the 1,200m strike extent that potentially extends known mineralisation and provide geophysical insights into several known yet underexplored nearby anomalies which includes previously mapped gossanous outcrops to the north-east of the recent drilling campaign conducted in Q4 2020. |
| Sample security |
· The measures taken to ensure sample security. |
· No new samples were taken. |
| Audits or reviews |
· The results of any audits or reviews of sampling techniques and data. |
· The data was collected by Fender Geophysics, with the data reduction and modelling being conducted by GeoDiscovery, both independent contractors to Castillo Copper |
(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 agreements or material issues with third parties such as joint ventures, partnerships, overriding royalties, native title interests, historical sites, wilderness or national park and environmental settings. · The security of the tenure held at the time of reporting along with any known impediments to obtaining a licence to operate in the area. |
· The following mineral tenures are held 100% by subsidiaries of Castillo Copper Limited, totalling an area of 736.8 km2 in the "Mt Oxide North Project" and as illustrated by Figure A2-3. o EPM 26574 (Valparaisa North) - encompasses the Big One historical mineral resource, Holder Total Minerals Pty Ltd, granted 12-June-2018 for a 5-year period over 100 sub-blocks (323.3Km2), Expires 11-June-2023. o EPM 26462 (Big Oxide North) - encompasses the 'Boomerang' historical Prospect and the 'Big One' historical mine, Holder: QLD Commodities Pty Ltd, granted: 29-Aug-2017 for a 5-year period over 67 sub-blocks (216.5Km2), Expires: 28-Aug-2022. o EPM 26525 (Hill of Grace) - encompasses the Ayra (previously Myally Gap) significant airborne EM anomaly, Holder: Total Minerals Pty Ltd for a 5-year period over 38 sub-blocks (128.8Km2), Granted: 12-June-2018, Expires: 11-June-2023. o EPM 26513 (Torpedo Creek/Alpha Project) - Granted 13-Aug-2018 for a 5-year period over 23 sub-blocks (74.2Km2), Expires 12-Aug-2023; and o EPMA 27440 (The Wall) - Granted on the 08-March-2021 over 70 sub-blocks (~215Km2) by Castillo Copper Limited. Expires 7th March 2026.
Figure B3 Castillo Copper Prospects (refer to link above)
· A check on the tenures in 'application status' was completed in 'GeoResGlobe' on the 15th May 2021. |
| Exploration done by other parties |
· Acknowledgment and appraisal of exploration by other parties. |
· Historical QDEX / mineral exploration reports have been reviewed for historical tenures that cover or partially cover the Project Area in this announcement. Federal and State Government reports supplement the historical mineral exploration reporting (QDEX open file exploration records). · Most explorers were searching for Cu-Au-U, and, proving satellite deposit style extensions to the several small sub-economic copper deposits (e.g., Big Oxide and Josephine). · With the Mt Oxide North Project in regional proximity to Mt Isa and numerous historical and active mines, the Project area has seen portions of the historical mineral tenure subject to various styles of surface sampling, with selected locations typically targeted by shallow drilling (Total hole depth is characteristically less than 50m). · The Mt Oxide North project tenure package has a significant opportunity to be reviewed and explored by modern exploration methods in a coherent package of EPM's, with three of these forming a contiguous tenure package. · Various Holders and related parties of the 'Big One' historical mining tenure (ML8451) completed a range of mining activities and exploration activities on what is now the 'Big One' prospect for EPM 26574. The following unpublished work is acknowledged (and previously shown in ASX releases' reference lists): o Katz, E., 1970, Report on the Big One, Mt Devine, and Mt Martin Mining Lease Prospects, Forsayth Mineral Exploration NL, report to the Department of Mines, CR5353, 63pp o West Australian Metals NL, 1994. Drill Programme at the "Big One" Copper Deposit, North Queensland for West Australian Metals NL. o Wilson, D., 2011. 'Big One' Copper Mine Lease 5481 Memorandum - dated 7 May 2011. o Wilson, D., 2015. 'Big One' Mining Lease Memorandum - dated 25 May 2015: and o Csar, M, 1996. Big One & Mt Storm Copper Deposits. Unpublished field report. · The reader of the current ASX Release is referred to the CCZ's first publication of the 1993 historical reverse circulation drilling results for additional diagrams and drilling information ("Historic drill data verifies grades up to 28.40% Cu from <50m in supergene ore at Mt Oxide Pillar") released on the ASX by CCZ on the 14-January-2020. · The SRK Independent Geologists Report released by CCZ on the ASX on 28-July-2020 contains further details on the 'Exploration done by other parties - Acknowledgment and appraisal of exploration by other parties' this report is formally titled "A Competent Persons Report on the Mineral Assets of Castillo Copper Limited" Prepared as part of the Castillo Copper Limited (ASX: CCZ, LSE: CCZ) LSE Prospectus, with the effective date of the 17-July-2020. |
| Geology |
· Deposit type, geological setting, and style of mineralisation. |
· The Mt Oxide North project is located within the Mt Isa Inlier of western Queensland, a large, exposed section of Proterozoic (2.5 billion- to 540-million-year-old) crustal rocks. The inlier records a long history of tectonic evolution, now thought to be like that of the Broken Hill Block in western New South Wales. · The Mt Oxide North project lies within the Mt Oxide Domain, straddling the Lawn Hill Platform and Leichhardt River Fault Trough. The geology of the tenement is principally comprised of rocks of the Surprise Creek and Quilalar Formations which include feldspathic quartzites, conglomerates, arkosic grits, shales, siltstones and minor dolomites and limestones. · The Project area is cut by a major fault zone, trending north- northeast - south- southwest across the permits. This fault is associated with major folding, forming several tight synclines- anticline structures along its length. · The Desktop studies commissioned by CCZ on the granted mineral tenures described four main styles of mineralisation account for most mineral resources within the rocks of the Mt Isa Province (after Withnall & Cranfield, 2013). o Sediment hosted silver-lead-zinc - occurs mainly within fine-grained sedimentary rocks of the Isa Super basin within the Western Fold Belt. Deposits include Black Star (Mount Isa Pb-Zn), Century, George Fisher North, George Fisher South (Hilton) and Lady Loretta deposits. o Brecciated sediment hosted copper - occurs dominantly within the Leichhardt, Calvert, and Isa Super basin of the Western Fold Belt, hosted in brecciated dolomitic, carbonaceous, and pyritic sediments or brecciated rocks proximal to major fault/shear zones. Includes the Mount Isa copper orebodies and the Esperanza/Mammoth mineralisation. o Iron-oxide-copper-gold ("IOCG") - predominantly chalcopyrite-pyrite magnetite/hematite mineralisation within high grade metamorphic rocks of the Eastern Fold Belt. Deposits of this style include Ernest Henry, Osborne, and Selwyn; and o Broken Hill type silver-lead-zinc - occur within the high-grade metamorphic rocks of the Eastern Fold Belt. Cannington is the major example, but several smaller currently sub-economic deposits are known. · Gold is primarily found associated with copper within the IOCG deposits of the Eastern Fold Belt. However, a significant exception is noted at Tick Hill where high grade gold mineralisation was produced, between 1991 and 1995 by Carpentaria Gold Pty Ltd, some 700 000 tonnes of ore was mined at an average grade of 22.5 g/t Au, producing 15 900 kg Au. The Tick Hill deposit style is poorly understood (Withnall & Cranfield, 2013). · ROM Resources had noted in a series of recent reports for CCZ on the granted tenures, that cover the known mineralisation styles including: o Stratabound copper mineralisation within ferruginous sandstones and siltstones of the Surprise Creek Formation. o Disseminated copper associated with trachyte dykes. o Copper-rich iron stones (possible IOCG) in E-W fault zones; and o possible Mississippi Valley Type ("MVT") stockwork sulphide mineralisation carrying anomalous copper-lead-zinc and silver. · The Mt Oxide and Mt Gordon occurrences are thought to be breccia and replacement zones with interconnecting faults. The Mt Gordon/Mammoth deposit is hosted by brittle quartzites, and Esperanza by carbonaceous shales. Mineralisation has been related to the Isan Orogeny (1,590 - 1,500 Ma). · Mineralisation at all deposits is primarily chalcopyrite-pyrite-chalcocite, typically as massive sulphide within breccias. · At the Big One prospect, West Australian Metals NL described the mineralisation as (as sourced from the document "West Australian Metals NL, 1994. Drill Programme at the "Big One" Copper Deposit, North Queensland for West Australian Metals NL."): o The targeted lode / mineralised dyke is observable on the surface. The mineralisation targeted in the 1993 drilling programmed is a supergene copper mineralisation that includes malachite, azurite, cuprite, and tenorite, all associated with a NE trending fault (062o to 242o) that is intruded by a porphyry dyke. o The mineralised porphyry dyke is vertical to near vertical (85o), with the 'true width' dimensions reaching up to 7m at surface. o At least 600m in strike length, with strong Malachite staining observed along the entire strike length, with historical open pits having targeted approximately 200m of this strike. Exact depth of mining below the original ground surface is not clear in the historical documents, given the pits are not battered it is anticipated that excavations have reached 5m to 10m beneath the original ground surface. o Associated with the porphyry dyke are zones of fractured and/or sheared rock, the siltstones are described as brecciated, and sandstones around the shear as carbonaceous. o The known mineralisation from the exploration activities to date had identified shallow supergene mineralisation, with a few drillholes targeting deeper mineralisation in and around the 200m of strike historical open cut pits. o A strongly altered hanging wall that contained malachite and cuprite nodules. Chalcocite mineralization has been identified but it is unclear on the prevalence of the Chalcocite; and o The mineralisation was amenable to high grade open pit mining methods of the oxide mineralization (as indicated by numerous historical open pit shallow workings into the shear zone). · Desktop studies commissioned by CCZ and completed by ROM Resources and SRK Exploration have determined that the Big One prospect is prospective for Cu, Co, and Ag. · Desktop studies commissioned by CCZ have determined the Boomerang prospect contains: o Secondary copper staining over ~800m of strike length. o Associated with a major east-west trending fault that juxtaposes the upper Surprise Creek Formation sediments against both the underlying Bigie Formation and the upper Quilalar Formation units. · At the 'Flapjack' prospect there is the additional potential for: o Skarn mineralisation for Cu-Au and/or Zn-Pb-Cu from replacement carbonate mineralisation, particularly the Quilalar Formation. o Thermal Gold Auroele mineralisation is a potential model due to the high silica alteration in thermal aureole with contact of A-Type Weberra Granite - related to the Au mineralisation; and/or o IOCG mineralisation related to chloride rich fluids. · At the 'Crescent' prospect there is the additional potential for: o Skarn mineralisation for Cu-Au and/or Zn-Pb-Cu from replacement carbonate mineralisation, particularly the Quilalar Formation; and/or o Thermal Gold Auroele mineralisation is a potential model due to the high silica alteration in thermal aureole with contact of A-Type Weberra Granite - related to the Au mineralisation; and o IOCG mineralisation related to potassic rich fluids. · At the 'Arya' prospect there is the additional potential for: o Supergene mineralisation forming at the surface along the fault, fault breccia, and the Surprise Creek Formation 'PLrd' rock unit ('Prd' historical). o Epigenetic replacement mineralisation for Cu (with minor components of other base metals and gold) from replacement carbonate mineralisation, particularly the Surprise Creek Formation. o Skarn mineralisation for Cu-Au and/or Zn-Pb-Cu from replacement carbonate mineralisation, particularly the Surprised Creek Formation. o Sulphide mineralisation within breccia zones, along stress dilation fractures, emplaced within pore spaces, voids, or in other rock fractures; and/or o IOCG mineralisation related to chloride rich fluids. · A selection of publicly available QDEX documents / historical exploration reports have been reviewed, refer to Section 2, sub-section "Further Work" for both actions in progress and proposed future actions. · The SRK Independent Geologists Report released by CCZ on the ASX on 28-July-2020 contains further details on the 'Geology - Deposit type, geological setting and style of mineralisation': this report is formally titled "A Competent Persons Report on the Mineral Assets of Castillo Copper Limited" Prepared as part of the Castillo Copper Limited (ASX: CCZ, LSE: CCZ) LSE Prospectus, with the effective date of the 17-July-2020. |
| Drill hole Information |
· A summary of all information material to the understanding of the 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. |
· This ASX release concerns itself with geophysical survey whereas previous ASX releases have discussed the 2020 drilling program in detail. |
| Data aggregation methods |
· In reporting Exploration Results, weighting averaging techniques, 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. |
· The new work was a ground geophysical dipole-dipole IP survey so there was no sample to aggregate. |
| Relationship between mineralisation widths and intercept lengths |
· These relationships are particularly important in the reporting of 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'). |
· The strike of the dyke is at 73 degrees (east) and variably 70-85 degrees dip to the south. The mineralised zones for copper (>500ppm) interested in drillholes range from 1m to 44m wide apparent, averaging 9m apparent (6.8m true width). The IP survey was designed to intersect the strike of the mineralisation at a perpendicular angle. · All mineralised intervals (i.e., >500ppm) have been reported in this and previous ASX releases as the "as-intersected" apparent thickness (in metres) and given that most drillholes dip at -60 degrees from the horizontal, true intersection widths will be less, but will be calculated during the block modelling process. |
| Diagrams |
· Appropriate maps and sections (with scales) and tabulations of 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. |
· Appropriate diagrams are presented in the body and the Appendices of the current ASX Release. Where scales are absent from the diagram, grids have been included and clearly labelled to act as a scale for distance. · Maps and Plans presented in the current ASX Release are in MGA94 Zone 54, Eastings (mN), and Northing (mN), unless clearly labelled otherwise. · A series of cross-sections were generated at Big One displaying copper analyses in ppm to aid interpretation and exploration planning as can be seen in Figure A2-4, below, which shows the geological section through which IP Line 3 traverses.
Figure B4: North-South Cross-section at BO_306RC (refer to link above)
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| Balanced reporting |
· Where comprehensive reporting of all Exploration Results is not practicable, representative reporting of both low and high grades and/or widths should be practiced to avoid misleading reporting of Exploration Results. |
· All survey lines except Line 6 which was scrapped in favour of extending Line 3 will be presented once fully interpreted. Line 2 is discussed at the end of this section. |
| Other substantive exploration data |
· Other exploration data, if meaningful and material, should be reported including (but not limited to): geological observations; geophysical 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. |
· Several airborne EM and magnetic surveys have been conducted nearby by historical explorers and Castillo Copper has conducted its own surface sampling program prior to drilling commencing as noted above. · As a result of further examination CCZ's geology team made the following recent key interpretations: o The full assay results, which included the entire twenty-one (21) drill-holes completed are awaiting some clarifications and re-assay of composites before a complete assessment of the data can be made and reported. o The presence of at least two mineralised lenses and a low-grade halo (100-1,500ppm) around the main ore body appears to hold along strike. o For drill-holes 213RC, 301RC, 303RC, 307RC, and 313RC the mineralisation is spread out which is significant given the trachyte to diorite dyke is generally 4-6m wide (refer Figure 1). o There is more than one dyke, however they may be offshoots of the main body. Compositions vary as rock types logged from the chips in both 1993 and the current campaign include trachyte, diorite, and granite (more probably a porphyritic syenite). o Some of the drillholes will need to be deepened (or used as a seed hole for downhole EM) as they appear not to have been drilled deep enough to intersect the projected dyke at depth. The affected holes are 201RC, 202RC, 203RC, and 304RC. o Planning for the IP Survey highlighted more target areas near Big One to the south and south-west where there are more trachyte dyke swarms that could be affected by structural control. |
| Further work |
· The nature and scale of planned further work (e.g., tests for lateral extensions or depth extensions or large-scale step-out drilling). · Diagrams clearly highlighting the areas of possible extensions, including the main geological interpretations and future drilling areas, provided this information is not commercially sensitive. |
· Future potential work is described within the body of the ASX Release, and will include: o Conduct a review all the IP lines (and integrating the assay data, known geology / geological model) to assess potential IP targets (as only 2 of the 6 IP lines acquired to date). Geological mapping and rock chip sampling over the anomalous chargeability zones along each survey line o Ground gravity and/or magnetic surveys. o Reverse Circulation Drilling o Diamond Coring. o Block modelling and wireframing. o Resource Estimation. |
Figure C1 shows a preliminary model of the first line of IP data collected (Line 2 - 10500). Note it is a preliminary model - in a new region it can take a couple of lines of data to refine some of the model parameters.
As lines are not east-west or north-south, data is being acquired in a local grid (which is needed in the modelling software). Once data has been acquired and modelled, it can be converted back to MGA space.
Figure C1: Line 2 IP Resistivity compared to Chargeability. (refer to link above)
Figure C1 displays the preliminary model for this line - the top image is a resistivity depth section (warm colours resistive and cool colours more conductive), the bottom image displays the chargeability depth model (higher chargeability's displayed in warm colours).
A few notes on the output to date:
· The section runs from NW-SE. The mineralisation and drilling to date is located between 5300 and 5250.
· The top resistivity model depicts a generally resistive environment. Some higher conductivity features are noted near surface between 5300 - 5100, which may reflect clays in topographically lower regions? Of interest, extending to depth (near vertically) at 5300 is a zone that displays an increase in conductivity - possible structure / dyke /? Note - this zone of increased conductivity does not directly correspond to the higher chargeability's (typical response of massive sulphides).
· The bottom chargeability model ranges between 0 - 10mV/V (low to moderate). A moderate IP anomaly is noted ~5275 at around 20 - 40m depth (dipping towards the SE). If this is the electrical signature of the known mineralisation at this location, we are looking at a resistive and moderately chargeable response adjacent to a steeply dipping zone of higher conductivity.
· Some regions of moderately high chargeability are noted near surface between 5150 - 5050. It would be worthwhile field checking this region to see if this near surface chargeable response can be explained. This region overlies a low chargeable / resistive response which may reflect the magnetic intrusions (heat / fluid source?).
· Note - higher chargeable values are also noted to the NW of the dyke 5400 - 5350. Mark, I understand that you initially believed this region to be less prospective. Is there anything in the mapped geology that could explain the chargeable response? If it is not easily explained - I would recommend extending line 1 to the NW, particularly as the magnetic model indicates the presence of a weak response near surface in this region.
· Typically, massive sulphides give a conductive and chargeable response and more disseminated sulphides display a resistive and chargeable response. The more oxidised Cu may be weakly chargeable.
Potential mineralisation extended at Big One 07:00:0920 May 2021Corporate updates2182Z