Heliborne Magnetic Survey Reveals Internal Architecture of the Oka Carbonatite Five Major Magmatic Structures with Potential REE Mineralization Defined
Heliborne Magnetic Survey Reveals Internal
Architecture of the Oka Carbonatite
Five Major Magmatic Structures with Potential REE
Mineralization Defined
Montreal, Quebec--(Newsfile Corp. - September 16, 2026) - Nio Strategic Metals Inc. (TSXV: NIO)
(OTCQB: NIOCF) ("
Nio
" or the "
Corporation
"), a critical mineral exploration company, is pleased to
announce the results and geo-structural interpretation of the high-resolution heliborne magnetic and
radiometric survey flown over its 100%-owned Oka property. The interpretation was recently completed
by Jean David, Senior Geophysicist, and Ali Ben Ayad, Senior Geologist, as the first phase of a
geoscientific compilation and synthesis of the historical geological and geophysical data on the Oka
carbonatite complex, undertaken with the specific objective of targeting rare earth element ("
REE
")
mineralization.
Since 1952, exploration at Oka has been directed almost exclusively at niobium, even though the
niobium-bearing zones are frequently accompanied by rare earth minerals, as shown by the first
analyses carried out in 1958 (Nickel, GSC), by various academic studies and, more recently, by the
Impact Global Solutions' ("
IGS
") metallurgical study (see the Corporation's press release of August 4,
2026). The new interpretation work integrates the 2023 survey data with seventy years of historical
drilling, trenching, mapping and academic research. This geoscientific compilation has brought to light
the three-dimensional architecture of the intrusion and the geo-structural settings most likely to host
significant REE concentrations.
The 2023 survey, flown by Prospectair, covered the entire property, including the North and South Rings
of the carbonatite and their Grenvillian host rocks: 921 line-kilometres on 25-metre line spacing, with a
magnetometer at a mean height of 33 metres and a gamma-ray spectrometer (potassium, uranium,
thorium) at 52 metres (Figure 1).
Figure 1.
Area covered by the 2023 magnetic and spectrometric surveys.
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The Oka magnetics show a highly variable total magnetic intensity (TMI, Figure 2) (range of 12,370 nT),
with strong magnetic anomalies forming triangular and/or crescent-shaped bodies characteristic of
dyke-type intrusives. The Grenvillian host rocks, to the north and east, show lower magnetic background
values and reduced variability, typical of areas dominated by metasedimentary rocks (paragneiss) or
felsic to intermediate intrusive rocks (orthogneiss). Figure 2 shows the position of the various
mineralized zones within and at the edge of the carbonatite complex on the magnetic maps, together
with its approximate interpreted contact.
Figure 2.
(a) Residual total field (TMI) and approximate limits of the carbonatite. (b) Magnetic tilt
derivative (TDR) and approximate limits of the carbonatite.
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The structural interpretation of the magnetic lineaments reveals several structures: ductile structures
within the Grenvillian rocks, shear zones (C1, C2, C3) and regional brittle structures. These lineaments,
highlighted by the various processing steps (filters), allow a structural scheme of the North Ring of the
carbonatite and its Grenvillian host to be proposed (Figure 3). This scheme shows the existence of three
major shear zones:
A shear corridor in the extreme northwest (C1), NE-trending and visibly sinistral, which truncates
the carbonatite and hosts the Advance showing.
A shear zone bounding the northeastern flank of the carbonatite at the contact with the Grenvillian
rocks (C2).
A sinistral strike-slip shear separating the North Ring from the South Ring of the intrusion (C3). It is
probably this fault that produced the "distortion of the number 8" cited by all authors who have
worked on this carbonatite (see Figure 4).
Figure 3.
(a) Residual total field (TMI) and interpreted structures. (b) Magnetic tilt derivative (TDR) and
interpreted structures.
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Figure 4.
Synthetic geological map of the Oka carbonatite showing the location of niobium showings
and mines (from Proulx, 2003, after Gold), illustrating the "distortion of the number 8" formed by the two
rings.
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Husereau Hill, according to the geophysics and field data, corresponds to one of the largest dykes,
located at the northern end of the carbonatite. Figure 5 clearly shows the lateral closure of this multiply-
filled dyke (fish shape). In the central part of the carbonatite (Figure 6), the large arcuate, crescent-
shaped magnetic structure of the Bond Zone also corresponds to a major dyke perfectly traced by the
magnetic susceptibility contrast.
Figure 5.
Surface geology of the Husereau Hill dyke (Gold and Vallée, S-101).
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Figure 6.
Identification of crescent-shaped, arcuate structures in the Oka carbonatite (on the magnetic
tilt derivative, TDR).
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Within the North Ring, five major magmatic structures have been defined, organized broadly along the
NW-SE elongation axis of the carbonatite. These dykes are strongly magnetic owing to the presence of
altered ultra-alkaline rocks (okaite and ijolite-urtite) and of their biotite- and magnetite-bearing
carbonatite host. From north to south, they are the Husereau, Manny North, Manny, Bond and Central
Structure (S60-Wayfair Zone) dykes. The magnetic inversion sections clearly individualize the different
dykes observed at surface, establish their overall dip and suggest a possible connection between all of
these dykes at depth (800 metres and beyond).
Within these dykes, several secondary magnetic axes are frequently observed, probably reflecting
multiple injections, separated by weakly magnetic intercalations of carbonate rocks, essentially dolomitic
to the north and calcitic towards the centre of the carbonatite. These carbonates are generally strongly
altered (carbonatization, biotitization) and carry magnetite, apatite and traces of pyrochlore and
perovskite. It is in these carbonates that rare earth elements have been reported by various authors
(Nickel, GSC, 1958; Eby, N., 1974), as REE carbonates (ancylite, bastnäsite) and phosphates
(monazite), always cryptocrystalline and/or intergrown, and probably also as inclusions in other minerals
(strontianite and barite), with grades in selected samples ranging from 1.5 to 4% total rare earth oxides.
Beyond the carbonatite host of the REE, the work of Nelson Eby (1974) helped identify the ultra-alkaline
silicate rock facies showing the greatest relative REE enrichment, namely, in decreasing order, the
okaites, the ijolites and finally the metasomatic contact facies between the carbonatite and its host
rocks, which are often digested by the calcitic carbonatite (ultrafenites). Among the minerals sampled
and analyzed in these silicate facies, the highest REE and yttrium concentrations occur in apatite,
niocalite, perovskite and pyrochlore.
In the calcitic carbonatite (sövite) at the core of the North Ring of the Oka intrusion (S60, Bond and
Wayfair niobium deposits), at least four generations of pyrochlore have been identified (Proulx, A.,
2003), and at least two of these niobium-rich pyrochlore generations also carry a radioactive signature
(Th and U) and are REE-rich. Among the REE, cerium is present at high concentration levels (between
2.1 and 15.8% CeO). It is associated with pyrochlore (ceriopyrochlore) and the other niobium minerals
(niocalite, perovskite), as well as with apatite and monazite, the latter being relatively abundant in this
central part.
In summary, three types of REE mineralization have been distinguished: REE associated with niobium
minerals (pyrochlore, perovskite and niocalite), REE associated with phosphates (apatite, monazite and
britholite) and REE associated with carbonates (ancylite and bastnäsite).
There is a strong correlation between these REE minerals and the presence of thorium anomalies and,
to a lesser extent, uranium anomalies. The same correlation exists with the niobium minerals and has
been used since the earliest exploration work (magnetic-radiometric prospecting); however, Nb
₂
O
₅
grades at these locations proved generally low (<0.45%), yet it is at these locations that the REE
minerals were discovered with the grades described above.
Given the radioactive character of the REE minerals recognized in the Oka carbonatite, any
concentration of these minerals is therefore expected to carry a signature that is primarily magnetic and
radiometric, expressed as a Th anomaly and, to a lesser extent, a U anomaly.
Overall, the integration of the high-resolution magnetic and radiometric data with the historical geological
data on the Oka complex has contributed to the geometric and structural understanding of the intrusion. It
provides not only a fairly detailed image of the magmatic structures but also strategic tools for identifying
zones favourable to REE concentration.
On the basis of the integrated interpretation, the technical team recommends a nine-hole
reconnaissance diamond drilling program totaling approximately 4,460 metres in the North Ring (Figure
7), with the primary objective of intersecting significant REE concentrations and, secondarily, niobium.
Figure 7.
Location of the proposed drill holes on the magnetic tilt derivative (TDR) map.
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Bruno Dumais, President and Chief Operating Officer, commented, "For seventy years, Oka was drilled
for niobium without anyone being able to see the whole system at once. This survey gives us that picture.
The dykes that carry the niobium are the same structures the historical work tells us carry the rare earths,
and we can now follow them at depth. This survey, together with the IGS metallurgical study and ongoing
test work, will help better understand the REE potential of the property and develop safer processes
regarding local environment."
The Corporation's next steps include working with the local stakeholders towards obtaining an
authorization for impact-causing exploration work (ATI) (
autorisation pour travaux d'exploration à
impacts
) within the framework and guidelines established by the Quebec Ministry of Natural Resources
and Forests (
Ministère des Ressources naturelles et des Forêts
).
As such, the Corporation has
mandated GHD Environnement to provide guidance and assure transparency of communication
throughout this process.
The technical information in this news release has been reviewed and approved on behalf of the
Corporation by Pierre-Jean Lafleur, P.Eng., a geological consultant and a qualified person within the
meaning of National Instrument 43-101 – Standards of Disclosure for Mineral Projects.
About Nio Strategic Metals