South Oko geophysics defines shear zone targets
Altair Minerals Limited
ABN: 72 149 026 308 +61 3 8630 3321 altairminerals.com.au Level 21, 459 Collins Street,Melbourne VIC 3000
ASX MARKET
ANNOUNCEMENT
Thursday 26 March 2026 ASX : ALR
SOKO Geophysics Define Shear Zone Drill Targets
Induced Polarization (IP) survey defines extension from Oko West with analogous and
coincident geochemical signatures
▪ Ground IP Chargeability & Resistivity at SOKO delineates the extension of Oko Shear contact – the key
structural corridor that hosts >9Moz Au over a 5km strike adjoining Altair.1,3
▪ 63km of IP survey lines successfully defines distinct geological units that align well with trench
observations, enabling the definition of clear drill targets coinciding with geochemical anomalies.
▪ Ground IP Chargeability & Resistivity at SOKO has been a critical step-forward to now define:
Continuity of structural corridor and Oko Shear Contact which hosts recent adjoining world
class discoveries.4
4.7km combined strike of distinct chargeability highs coinciding with soil anomalies, for drill
testing and analogous to Oko West ground IP chargeability.
Priority drill targets to be tested during maiden RAB and diamond drill programs.
Definition of contact and key splay structures to be followed up with geochemical surveys.
▪ "W1-C" Chargeability Anomaly: Prominent chargeability anomaly extending over 1.1km strike.
Spatially coincident with the W1 soil anomaly, including the peak value of 888ppb Au.
Overlaps the eastern portion of the W1 anomaly (50 to >200ppb Au) and aligns with the
proximal 7.02 g/t Au grab sample.
Remains open to the north, with the northernmost soil sample on W1-C returning 340ppb Au –
indicating strong upside potential.
▪ "W3-C" Chargeability Anomaly: Akin to Oko West, a distinct ~1km strike chargeability high
'sandwiched' between two chargeability lows – mirroring the orientation of the W3 soil anomaly.
Both SOKO's W3-C and Oko West's 'Block 4' chargeability highs measure ~900 – 1,100m in
strike extent and ~200m in width, both occurring between chargeability lows.
Located approximately 800m west of the Oko Shear Contact, with chargeability peaks aligning
closely with the W3 soil anomaly.
W3-C also coincides with a major resistivity high, potentially indicating a fractured/sheared
host infilled with a quartz-sulphide vein swarms.
▪ "W1-R" Resistive Anomaly: An analogous anomaly structure to Oko West, with a resistive response
occurring between two resistive lows, adjacent to the Oko Shear Contact.
Coinciding with a 650m strike extent, >200ppb Au soil anomaly sitting directly on top of W1-R
resistive anomaly.
Akin to Oko West, W1-R also presents a corresponding chargeability response labelled as
"W4-C".
▪ During April 2026, Altair expects a major step-change in the scale of its exploration programs,
commencing and executing multiple high-impact work programs in parallel:
Diamond drilling to commence at North Peters
RAB drilling to commence
Auger drilling to continue
Soils and trenching to continue at SOKO with new local target areas to be tested
District-scale geophysical surveys at broader SOKO – LiDAR and Aeromagnetics
Altair Minerals Limited CEO, Faheem Ahmed, commented:
"I'm pleased to present our initial ground geophysics results for IP chargeability and resistivity surveys,
which mark another important step forward in defining high priority drill targets and clearly reaffirm the
extension of the Oko Shear Contact.
With both ground magnetics and pole-dipole surveys near completion, we expect to further strengthen our
targeting capacity and develop a more holistic understanding of the geological and structural framework.
We now have a clear understanding of the Oko Shear Contact position, supported by key chargeability and
resistivity anomalies that coincide with the soil geochemical trends. This represents a significant milestone
at SOKO – validating our exploration model and reinforcing the potential for a major discovery.
With the majority of preliminary geochemical works now complete across our primary SOKO targets, our
focus will shift to auger drilling and trenching to further refine these highly anomalous targets ahead of the
imminent RAB drilling program.
At the same time, ongoing soil sampling will target new prospective areas identified from recent fieldwork,
testing both along strike and parallel structures to the Oko Shear Contact. This systematic approach ensures
a strong pipeline of multiple high-potential targets, supporting our vision of advancing Greater Oko into a
district-scale asset capable of delivering multiple significant discoveries.
We continue to progress all work programs aggressively to commence our maiden drill programs in April,
which will mark a major step-change in the scale of our exploration."
Figure 1: Plan view of the Greater Oko Project and four key target areas defined to date – South Oko (SOKO), North Peters
(NP), Old Granny (OG) and Kmung (KM) with Altair's project size in comparison to its two predecessors G2 Goldfields
($2.2 Billion Market Cap) and GMining Ventures ($1 Billion takeover of Oko West from Reunion Gold). For clarity, both G2
and GMIN resources are located outside of Altair's Greater Oko Project.1,2,3,4,9,10,11,12,13,14,19,20
South Oko ('SOKO') Ground IP Survey
Altair Minerals Limited ("ALR") is pleased to report the completion of ground gradient array IP survey at the
SOKO prospect, which has delineated the extension of the Oko Shear Contact and identified prominent
chargeability and resistivity anomalies coincident with geochemical peaks, enabling the definition of priority
drill targets.
Ground magnetics and pole-dipole surveys are currently in their final stages, with results expected shortly
after. Ground magnetics will assist in defining key structural features favourable for gold emplacement,
while the pole-dipole survey will provide a 3D perspective, enhancing understanding of geological and
structural continuity at depth.
The IP gradient surveys were conducted at 200m spaced lines and 37.5m spaced electrodes, with 63km of
lines covering the north-south strike across the SOKO prospect.
Results from the IP survey confirm the continuation of the main structural corridor that hosts neighbouring
world-class deposits, adjoining Greater Oko. Importantly, the survey has materially increased confidence in
drill targeting and prioritization, demonstrating that peak chargeability and resistivity anomalies align closely
with existing soil geochemical anomalies.
IP RESISTIVITY
The IP resistivity survey at SOKO enables identification of:
▪ Resistive Highs (Competent Units) – Granite, intrusions, silicification from hydrothermal gold-bearing
fluids, unaltered mafic volcanics.
▪ Resistive Lows (Incompetent Units) – Structural deformation, shearing, hydrothermal alteration,
sedimentary units.
At SOKO, the resistivity survey has been highly beneficial in refining drill targets and reaffirming the overall
exploration model through clearly identifying the Oko Shear, with key outcomes demonstrated through:
1. Definition of the Oko Shear Contact:
Defined through the sharp contrast from resistive high to low, with precise continuity and
alignment from GMining Ventures resistivity survey and Oko Shear Contact.1
Improving exploration efficiency for Altair to focus on the western portion of the contact
(greenstones) and following the structural system along strike with geochemical programs.
2. Clear definition of distinct lithological packages, analogous to the sequence which has led to
>9Moz discoveries along strike1,3. Defined by sharp contrasting resistivities and robust
anomalies, going from east to west:
Felsic Metamorphosed Granite/Bartica Gneiss – defined by a resistive high.
Oko Shear contact – defined by a sharp contrast between resistivities.
Volcanic-sedimentary units and alteration – defined by a transition into moderate to low resistive
response.
Mafic volcanics, intrusions, silicified margins and structurally deformed gold traps – defined by
a transition back into resistive highs.
3. Refinement of drill targets through clear resistive responses in favourable host units, which
coincide with soil anomalies and chargeability targets.
High Contrast Resistivity – Regional Map
Figure 2: High contrast smoothened ground IP resistivity survey for both GMining Ventures Oko West Project and Altair
Minerals South Oko Project areas. WGS84, UTM Zone 21N.1
Resistivity Targets
Within Figure 3 below, the Oko Shear Contact can now be clearly defined by the contrast between the
resistive high and adjacent lows. This SOKO structural extension aligns concisely with the structural
mapping and corresponding IP resistivity from the Oko West Project (see Figure 2).
Detailed IP Resistivity Survey – SOKO
Figure 3: Detailed ground gradient array IP Resistivity Survey at SOKO. WGS84, UTM Zone 21N.
W1-R Target
Within Figure 3 above, the broad resistivity low to the west of the Oko Shear Contact represents a package
of highly weathered and oxidised volcanic-sedimentary units. Within this unit, the W1-R target (~1.0km
strike) presents a distinct resistive/chargeability high 'sandwiched' between the resistive lows indicating:
a) Potential Structural Trap – The bend/jog on Oko Shear Contact developing a fractured pervasive
quartz-sulphide vein swarm (resistivity high, chargeability high).
b) Potential Lithological Trap – Interbedded lens of competent intermediate/mafic units (resistive high)
which has undergone brittle deformation and allows gold and sulphides to precipitate between the
porosity (chargeability high).
The W1-R target aligns concisely with a 650m corridor of >200ppb Au gold-in-soil anomaly.
Soils Overlay & Detailed IP Resistivity Survey – SOKO
Figure 4: Same as Figure 3, with soils results reported to date overlaid onto IP resistivity. WGS84, UTM Zone 21N.22
IP CHARGEABILITY
The chargeability survey at SOKO enables identification of:
▪ Chargeability Highs (Polarized Units) – Disseminated sulphides (associated with gold mineralisation),
hydrothermal alteration, shearing and metamorphic margins, carbonaceous shales.
▪ Chargeability Lows (Non-Polarized Units) – Granitic units, oxidation, intrusions, silicified units.
At SOKO, the chargeability survey has vectored towards defining priority drill targets, underpinned by
distinct chargeability highs which co-align with structural corridors and peak soil anomalies. The key
outcomes of the chargeability survey highlighted by:
1. Clear definition of the Oko Shear Contact
Metamorphosed Granite/Bartica Gneiss defined by a chargeability high and sharp contrast into
highly sheared and altered volcanic-sedimentary units (chargeability low).
2. Highly silicified margins and competent wall-rocks
Silica being a near perfect electrical insulator, generating a chargeability low in conjunction with
a resistive high.
3. Four distinct chargeability targets
Distinct corridors of chargeability highs, indicating to potential sulphide bearing host units,
aligning with soil anomalies and quartz related silicification from coinciding resistive highs.
Chargeability Targets
Figure 5: Image left – Oko West ground IP Chargeability. Image centre – SOKO Ground IP Chargeability. Image Right –
SOKO Ground IP Chargeability overlay with soil sampling results to date. Note the purpose is to demonstrate to overall
structural contrast and 'sandwich' structure present between chargeability highs and linking back to the geological
outcome. WGS84, UTM Zone 21N. 1,22
Within Figure 5 above, the IP gradient array chargeability survey has identified distinct peaks and identified
4 key target areas, W1-C, W2-C, W3-C and W4-C (corresponding with W1-R, mentioned above).
On the left-hand image of Figure 5, the Oko West chargeability model is shown which demonstrates the
'sandwich' chargeability anomaly between two lows – representing the sulphide/sedimentary lens between
the granitoid intrusion (low) and Oko Pluton/Bartica Gneiss (low). This presents a rheological contrast which
allows for significant shearing and deformation of the package between two competent units.
Similarly, in Figure 5, within SOKO, multiple distinct chargeability targets are presented, which are
'sandwiched' between chargeability lows, presenting high-priority drill targets.
W1-C Target
Within Figure 5, the W1-C target is a prominent 1.1km strike length, chargeability high, which borders the
sedimentary units to the east as seen by the chargeability low. The saprolite volcanic-sedimentary unit to
the east of this target has been identified and confirmed through logging of trenches – Trench Number 4 (~3m
depth) and deeper Trench Number 5 (~6m depth).
This chargeability high represents a likely increase sulphidation, which remains open to the north, coinciding
with the soil anomalies, including peak soil anomaly to date of 888ppb Au and adjacent to grab sample
returning 7.02g/t Au taken ~200m to the east of the W1-C target.
To the north of the W1-C target shows a notable decrease in the resistivity, whereas chargeability remains
robust. This indicates that the potential main silicified plumbing system is positioned south of the W1-C
target (resistive high), which is then surrounded by a sulphide rich halo (chargeability high), likely to result
from a hydrothermal gold bearing fluid interacting with a favourable host rock and presenting a high-priority
drill target.
W3-C Target
Within Figure 5, the W3-C target is a distinct chargeability high of 1km strike length, which coincides with the
positioning of the W3 soil anomaly and a major resistive high – indicative of a potential quartz and sulphide
vein swarm as a resultant of an emplaced hydrothermal gold system.
More interestingly, directly adjacent to the west of the W3-C target a resistive high and chargeability low
corridor is present. This adjoining resistive high/chargeability low to the west of W3-Cis potentially indicative
of:
a) Silicified wall-rock – Due to quartz being incredibly resistive (resistive high) and a near perfect
electrical insulator (chargeability low) which has a highly chargeable gold bearing sulphide unit
adjoining it (W3-C target)
b) A competent rheological boundary, such as a granitoid intrusion (resistive high, chargeability low)
preventing further movement of hydrothermal fluids, with sulphides precipitated at the adjoining
W3-C target
W2-C and W4-C Target
Within Figure 5, the W2-C target shows another distinct large and prominent chargeability high sitting
beneath the duricrust, which represents a blind drill target.
W4-C Target remains highly prospective, not only due to the resistive high 'sandwiched' between two lows,
which indicate an increase in quartz and mafic units, but also corresponding with a distinct increase in
chargeability, reaffirming the potential for quartz-sulphide swarm which have been packaged and sheared.
Next Steps
The W1-R, W4-C, W1-C and W3-C represent immediately high-priority targets to be drill tested through a
comprehensive RAB and diamond drilling program scheduled for SOKO.
Altair is currently finalising ground magnetics survey alongside Pole-Dipole survey, which will give a clear
understanding of key structural controls, faults and lineaments alongside the vertical continuity of each
lithological package/structure.