Border Downs

Geological setting and mineral system

The target sits at the Curnamona Province – Delamerian Orogen boundary within the outcrop-poor Thomson cover region, beneath approximately 442 m of Eromanga/Darling Basin cover; basement is interpreted as probable Middle to Late Neoproterozoic quartz-rich shallow-marine clastics (R00036180). The intersection is recorded in GSNSW MinView as MIN_043525 (drill type Other — water bore; business purpose metallic minerals), with the mineralisation documented by the GSNSW New Frontiers core-tails programme (Dick & Simpson 2010, GS2010/0173, R00036180). The style is vein- and breccia-hosted galena–sphalerite–pyrite in black shale — hydraulic breccia and folded carbonate–quartz veins, interpreted as a structurally and hydrothermally controlled epigenetic system, not a stratabound lode. The hole sits on the slope of a medium-value magnetic ridge (TMI RTP interpretation) and on the western flank of a gently north-east-dipping horizon interpreted from the 1970 SS087 seismic line — a structural framework, not a modelled ore-body response. The Koonenberry / Kantappa corridor is a candidate — not a demonstrated — mineralising control (R00005275). Sphalerite is a geochemical inference from the Zn–Cd–In tenor rather than an observation in thin section, and no historical hole other than the water bore itself has reached the mineralised basement position.

The grades — what the system has already demonstrated

Result (GSNSW open-file, verbatim-sourced)	Confirmation status and resolving action
G09/43: 5,055 ppm Pb, 3,470 ppm Zn, 24.8 g/t Ag, 35.7 ppm Cd, 21.0 ppm Sn, 1.9 ppm In over 0.23 m (455.40–455.63 m), Certificate L082316 (R00029820; R00036180)	Government-generated: GSNSW-sampled (2009), government laboratory (2010) — but a partial (mixed-acid) digest, three samples, no QAQC; the synthesis states it confirms sulphide is present but is not a sound basis for a reported grade. No independent re-assay yet exists; the resolving action is the pre-committed total-digest re-assay (~A$5–20k). Collar carries an unresolved ~100 m E / ~300 m N inter-source discrepancy (synthesis Appendix C), resolved by Phase 0 DGPS survey.
G09/44: 7,440 ppm Zn, 2,340 ppm Pb, 3.0 g/t Ag, 57.4 ppm Cd over 0.21 m (455.80–456.01 m), Certificate L082316 (R00029820)	Same certificate and digest basis. Spot maxima, not interval grades — the adjacent 0.12 m sample (G09/42) returned 50 ppm Pb; only ~0.56 m of core was assayed across a ~1.5 m envelope.
Galena Pb isotopes: ²⁰⁶Pb/²⁰⁴Pb 18.515–18.526 (Carr 2012, Sirotope, R00029985)	Two analyses in a report marked draft, on mixed-sulphide scrapings, University of Melbourne MC-ICP-MS; interpreted as clearly post-Proterozoic, unlike any entry in the SIROTOPE database, probably Palaeozoic to Mesozoic. Confirmatory non-draft analysis on a clean galena separate is a designed Phase 1 item (synthesis Appendix E, M1).
District — Teilta (TD9210): up to 3,850 ppm Zn over 3 m, including a 6 m interval of 2,730 ppm Zn (64–70 m) (R00005276)	BHP final-report data; a granite-related greisen Zn occurrence of different style, undated — a permissive district backdrop indicating non-Willyama sulphide is present, not corroboration of the Border Downs system.

Exploration history — three operators, documented exits

Three campaigns, three documented model-driven exits — and the mineralised intersection itself was drilled by government; no operator has tested it under a non-Willyama model
Period	Operator (licence)	Model targeted	Departure reason
1976–77	WMC (ELs 868–870)	Tertiary sediment-hosted Cu–U	Encouraging bore-water Cu attributed to machinery contamination; licences relinquished (R00013381)
1980	Mobil Energy Minerals (EL 1205, Lake Wallace)	Regional gravity-closure target	Gravity feature attributed to broad regional structure and pre-Tertiary topography, not mineralisation (R00012884)
1991–93	BHP Minerals — Tindara (ELs 3952–3963, 4005–4009, 4140)	Broken Hill–type Willyama Pb–Zn–Ag	No prospective Willyama Supergroup equivalents and no significant mineralisation identified; tenure relinquished (R00005275; R00005276)
2009–12	GSNSW / NSW Office of Water (New Frontiers — no mineral title)	Stratigraphic water-bore core-tail — not an exploration model	Data released to open file; no explorer has since actioned the intersection or the 2012 isotope result (R00036180; R00029985)

Why the grade is still available — what the record shows

Wrong commodity, wrong model. Every historical operator targeted Broken Hill–type Willyama Pb–Zn–Ag or sediment-hosted Cu–U. BHP's recorded basement across Tindara was greenschist-facies Adelaidean metavolcanics and metasediments, Delamerian granite and hornfels — its reports record that no prospective Willyama Supergroup equivalents were identified, and the ground was relinquished (R00005275; R00005276). Mobil recorded its gravity feature as regional structure and pre-Tertiary topography (R00012884); WMC attributed its bore-water copper to machinery contamination (R00013381). The model now proposed — a post-Proterozoic, structurally controlled epigenetic system — post-dates every exit: the discriminating isotope data were produced in 2012, after the last operator had left.

The analytical gap. The only assays on the intersection are a 2010 three-sample partial (mixed-acid) digest run with no certified reference materials, blanks or duplicates (R00029820) — the synthesis names this as an explicit limitation and records that resistate phases (Sn as cassiterite, W, the rare-earth elements) are those most likely to be under-reported by a partial digest. The Cd (to 57.4 ppm), In (1.9 ppm) and Sn (21.0 ppm) tenor is consistent with a sphalerite-bearing polymetallic assemblage; the residence of indium in sphalerite is a conventional assumption [not yet demonstrated]. A GSNSW report by David Forster covering ore microscopy, sulphur isotopes and lead isotopes was noted as in preparation in R00036180 and has not been located [not yet located]; the synthesis ranks its recovery as the single highest-value desktop action (Appendix E, G1).

The untested target. No historical operator ever drilled toward this intersection — the hole that found it is a water bore, core-tailed incidentally. In the synthesis's formulation, the intersection has not been drill-tested for this (non-Willyama) model, and no geophysical anomaly specific to the post-Proterozoic, structurally controlled model has yet been defined at the collar. The post-Proterozoic galena signature — unlike any entry in the SIROTOPE database — has never had a hole designed against it. 

The miss, precisely. The mineralised intersection was never found by an explorer and never missed by one: it was drilled by a government water bore, core-tailed incidentally, and released to open file. The three historical campaigns had already relinquished the district — each screening against a Willyama or sediment-hosted Cu–U model — before the discriminating evidence existed: the assays were reported in 2010 and the post-Proterozoic isotope result in 2012, after the last exit. The result is a documented polymetallic intersection that no company has ever held title over, assayed by total digest, or drill-tested — in the synthesis's formulation, the intersection has not been drill-tested for this (non-Willyama) model.

System scale — measured dimensions and the conservative case

Dimensions, not tonnes. What is measured: a 3 m HQ core-tail (454–457 m) with a ~1.5 m mineralised envelope, of which ~0.56 m was assayed, ~12–15 m into basement beneath ~442 m of cover; a medium-value magnetic ridge at the collar (TMI RTP) and a north–south seismic horizon (SS087) dipping gently north-east; and a district spread of three non-Willyama occurrences (Border Downs, Mule, Teilta) along the candidate Koonenberry / Kantappa corridor. True width, geometry, continuity, plunge and footprint are explicitly not yet measured — the system class is untested laterally and at depth. The conservative case is stated in the synthesis and belongs on the table: the headline grades are point maxima from 0.21–0.23 m spot samples, and the mineralised structure may be a few centimetres wide; alternatives consistent with the same data — an isolated non-economic occurrence, remobilised lead in a structural trap, or a distal intrusion-related (greisen/skarn-distal) system — are set out with their discriminants in synthesis §5.4. Model-class descriptors apply to the class, not the project, and no commercial or price argument is made in Synthesis v4.0, so none is summarised here.

The targets

Primary — the DDH1 vein–breccia intersection at the resolved collar. Known technical limitation, stated plainly: the magnetic-ridge association is an interpretation of a medium-value TMI RTP feature — no geophysical response specific to this model has been defined at the collar, prior magnetic and gravity surveys were designed for Willyama targets, and the collar itself carries the ~100 m E / ~300 m N discrepancy. The designed resolution is sequential: DGPS collar re-survey, ground magnetics/gravity and IP and/or AMT with reprocessing of the BHP 1991 aeromagnetics and SS087 seismic (Phase 0), then BD-DDH001, a ~560 m vertical twin of the resolved collar (oriented core, gyro, DHEM).

Secondary. (i) The across-strike structural target — BD-DDH002, inclined ~−60°, ~580 m, azimuth and dip finalised from Phase 0 and any oriented-structure data from 001. (ii) The district corridor — plotting Border Downs, Mule and Teilta against the Curnamona/Delamerian boundary and the Koonenberry / Kantappa corridor to test for a controlling trend (desktop). (iii) The intrusion-related alternative — a concealed intrusive-contact vector, discriminated by the same re-assay, ore-microscopy and geophysics sequence.

Testing the thesis — gates, kill criteria, cost to answer

Phase + cost	Scope	Gate & kill criterion
Re-assay gate (Step 0 + kill-or-confirm) — ~A$5–20k	Recover the 2010 pulps/rejects before any core is cut; else sample the retained Londonderry box (4O/L2/5). Total-digest re-assay: ALS ME-MS61 four-acid backbone, ME-MS81 lithium-borate fusion for In/Sn/W/REE, fire assay for Au; full QAQC (CRMs, blanks, duplicates); relog, recovery/RQD, ore microscopy.	Pre-committed, binary: proceed only if four-acid Pb+Zn reproduce within ~20% of the 2010 values and In/Sn confirm above detection; kill if the base metals collapse, if relogging shows a <0.2 m structure with no logged continuity, or if ore microscopy shows the Pb–Zn is a trace, isolated phase. The kill answer for the grade costs ~A$5–20k and is binary.
Phase 0 — target definition, ~A$0.10–0.18M	DGPS collar resolution; ground magnetics and gravity; IP and/or AMT; reprocessing of BHP 1991 aeromagnetics + SS087 seismic; petrophysics on retained core; approvals, heritage and landholder engagement run in parallel.	Gate A: proceed to drilling only if the collar is resolved and geophysics defines a coherent, drill-ready target. A negative geophysical result re-frames the play to the conservative (narrow-structure) case before any drilling capital is committed.
Phase 1 — verification drilling, ~A$0.65–1.0M (central ~A$0.825M)	BD-DDH001 (~560 m, vertical twin) and BD-DDH002 (~580 m, inclined ~−60°, azimuth from Phase 0); mud pre-collar + oriented HQ→NQ core; gyro survey, DHEM, spectral scanning, density; ~1-in-20 CRM/blank/duplicate insertion plus umpire pulps at a second laboratory. NSW CMEP co-funded drilling (anticipated Round 2, ~September 2026) to be pursued as a Phase 1 offset.	Gate B: proceed to Phase 2 only if drilling confirms mineralisation with a defined orientation and encouraging tenor/width, and/or a DHEM/IP vector is identified — the drill design's continuation-versus-kill rule. Down-hole EM is run in each completed hole before any Phase 2 commitment.
Phase 2 — extension (contingent), ~A$0.8–1.5M	2–4 step-out / depth-extension holes at nominal 50–150 m offsets on the DHEM/IP vectors and measured structural orientation; hole count, spacing and depth set by the Phase 1 outcome, not pre-committed.	Gate C: assess whether results support progression to a JORC-ready dataset and Table 1 assessment ahead of any public disclosure.

Technical Manager: Dr Tim McConachy FAusIMM (1974), Senior Fellow SEG, former Rio Tinto Chief Geologist.

Data room (under NDA): technical synthesis v4.1, Phase 1 drill programme design, source register and figure set.

Contact: Doug Alcock, Managing Director, CAADIA Metals Pty Ltd — dalcock@caadiametals.com.au

No JORC (2012) Mineral Resource, Ore Reserve or Exploration Target is declared or implied. Historical results are compiled from GSNSW open-file (DIGS) records, have not been verified by a Competent Person for public reporting, and are provided for context only. The IRGS / distal-replacement interpretation is a working hypothesis under test; alternative interpretations of the geophysical data exist. Earn-in terms are indicative and non-binding, subject to contract, due diligence and grant of the Exploration Licence.