TIDMEEE
RNS Number : 9420D
Empire Metals Limited
25 October 2022
Empire Metals Limited / LON : EEE / Sector: Natural
Resources
25 October 2022
Empire Metals Limited
("Empire " or "the Company")
"Giant" Copper Province Potential at Pitfield Confirmed by
Expert Review
Empire Metals Limited (LON: EEE), the AIM-quoted resource
exploration and development company, is pleased to announce the
results of an expert review on the Pitfield Copper Project
('Pitfield'), located in Western Australia. Results from the review
which evaluated recent geophysical surveys and the historical
exploration database at Pitfield, confirmed that Pitfield has all
the hallmarks of a "Giant" copper mineralised system.
Highlights
-- Pitfield confirmed as having all the hallmarks of a "Giant"
copper mineralised system, potentially containing multiple
sediment-hosted stratabound copper (SSC) deposits.
-- An exceptionally large, magnetic anomaly, extending over 40km
N-S has been identified at Pitfield.
-- SSC deposits are globally significant geological systems
which deliver 20% of copper production globally and are often very
large and high-grade deposits.
-- The Pitfield geological setting compares favourably with the
sandstone sub-type of SSC, exemplified by the massive Udokan Ore
Region in Russia.
-- Empire to accelerate exploration activities at Pitfield in Q1
2023 including surface mapping, Induced Polarisation (IP) surveying
and geochemical sampling with multiple exploration targets already
identified
-- Expert Review undertaken by the Company's exploration team
under the supervision of Ed Baltis (Exploration Consultant) who has
more than 30 years' experience with Western Mining Corporation,
Gold Fields and as a consultant in gold, copper and nickel
exploration with a strong focus in Western Australia, and Dr Neil
O'Brien, a PhD economic geologist and former mining executive with
35 years of international experience including with Giant copper
deposits worldwide.
Shaun Bunn, Managing Director, said: "We previously held a
strong belief that Pitfield had the potential to contain a major
copper deposit with world-wide significance. The results of this
expert review, which drew on the findings of the recently completed
geophysical surveys, confirm the accuracy of the historical data we
inherited and have identified the regional geological features
consistent with a Giant copper mineralised system. This makes
Pitfield an exciting exploration target for a SSC deposit and an
exceptional project for us to focus our exploration efforts on.
"SCC type deposits are often very large and high-grade deposits
and account for approximately 20% of the world's copper production.
We are looking forward to increasing our understanding of Pitfield
as we embark on our next phase of exploration which will include
surface mapping, Induced Polarisation (IP) surveying and
geochemical sampling. Work is expected to commence in Q1 2023."
Technical Highlights
-- Pitfield lies within the Neoproterozoic Yandanooka
intracratonic sedimentary basin which has all the hallmarks of a
"Giant" copper mineralised system, potentially containing multiple
SSC deposits.
-- The Neoproterozoic is one of the major SSC mineralisation
epochs, temporally associated with the break-up of the Rodinia
supercontinent and is associated with several of the largest copper
SSC deposits discovered to date, the most important deposits being
located in the Central African Copperbelt of Zambia and the
DRC.
-- Widespread copper, silver, nickel and zinc anomalism has
already been identified over large parts of the Yandanooka basin by
previous explorers, particularly in association with
magnetite-altered rocks.
-- An exceptionally large, oxidised fluid event has occurred,
extending over 40km N-S, as evidenced by magnetite-altered
stratigraphy and corresponding reduced conductance - likely due to
removal of graphite in the siltstone.
-- This basin-scale alteration extends beyond the magnetite
altered domain as seen in sporadic diamond drilling (which also
indicated widespread Cu depletion in the basement rock) and the
formation of the Three Springs (Imerys) talc deposit to the
immediate east of Pitfield.
-- Our Pitfield geological model is based on a basin scale
alteration event, involving hot oxidising, fluids carrying copper
leached from the "red beds" and basement mafic rock, which upon
contact with reductants within the upper siltstones/sandstones
resulted in the copper precipitating and depositing along the
reduced stratigraphic layers.
Future Work Planned
Pitfield remains an early phase exploration project and as such
requires further surface exploration work to effectively define
geochemical (soils, auger and AC drilling) and geophysical
anomalies (electrical surveys such as IP) prior to evaluating their
economic significance through drilling.
The interpretive geological mapping has provided multiple
exploration targets which will be followed up with further field
work in the coming months. Land access agreements with local
farmers are required for some of the areas of interest.
Geological Model for a Sediment-Hosted Stratabound Copper
Deposit
SSC deposits are the second most important source of copper in
the world behind porphyry copper deposits. Around 20% of the copper
in the world is produced from this class of often very large and
high-grade deposits. These deposits a lso typically have potential
for large scale, low-cost bulk mining.
SSC deposits are bodies of disseminated, cementing, and lesser
veinlet-hosted copper (Cu) minerals that typically follow the same
structures within their sedimentary or metasedimentary host rocks.
These SSC deposits are characterized by strong zoning of the ore
minerals laterally along and across the host rock bedding from
pyrite, to chalcopyrite, to bornite, to chalcocite, and to
hematite. Chalcocite and bornite zones are typically the ore
zones.
SSC deposits occur where there are strong reductants present
that can precipitate sulphur (S) and copper (Cu) from warm ( 75-220
degC), oxidized (hematite-stable), metals-transporting, sedimentary
brines.
They are divided into three sub-types of deposits based on rock
varieties:
-- reduced facies type deposits (e.g. Kupferschiefer) are hosted
in black to gray to green shales or siltstones;
-- sandstone-type deposits (e.g. Revett) are hosted in gray,
well-sorted, fine to coarse grained sandstones; and
-- redbed-type deposits are hosted in otherwise oxidized sandstones.
These host rocks either lie atop or are enclosed within thick
(greater than 300m and commonly greater than 1km) sequences of red
beds. The association with red beds is an important distinction
from other Cu deposits found in sedimentary rocks.
SSC deposits are an important source of other metals, ranking
first among all deposit types in the world for cobalt (Co)
production and fourth among all deposit types in silver (Ag)
production. However, those that contain byproduct Ag do not contain
byproduct Co and vice versa.
The important key parameters that, when found in combination can
lead to a world class SSC deposit (as illustrated in Figure 1.)
include:
-- intracratonic rift basin setting allowing oxidised fluids to
evolve and persist for a significant period - in other words a
"closed" basin;
-- a basal sequence of red bed sediments that provide a source
for oxidized fluids and metals (red beds being hematite-bearing
sandstones, conglomerates, siltstones), the presence of reduced
carbonaceous rocks (containing organic matter, graphite or
hydrocarbons) stratigraphically higher in the sequence that provide
a redox trap to allow for the precipitation of copper;
-- a basin scale oxidised fluid flow system that leaches large
areas of source rocks,ideally over a prolonged period of time.
Figure 1: Conceptual sequence favourable for SSC deposits
(Hitzmann et al Economic Geology 2010)
Pitfield Copper Project Comparison with the SSC Model
Pitfield lies in a unique setting along the boundary of Western
Yilgarn province, where a major craton-scale structure internal to
Southwest Gneiss province intersects and offsets the Yilgarn margin
and controls the position of the Neoproterozoic Yandanooka basin,
the only example of this globally important copper prospective age
adjacent to the western Yilgarn craton (Figure 2).
Figure 2- Location Map - Showing Yandanooka Basin
Surface geological and structural mapping has been combined with
the new geophysical mapping and historical drillhole logging to
produce a detailed geological interpretive map of the basin and
surrounding region which clearly shows the structures most
prospective for a SSC deposit, and in particular the Mt Scratch
siltstones (Figure 3).
Figure 3: Pitfield Interpretative Geology and Structural Map
The 9,000m thick Mt Scratch siltstone has been subdivided based
on geophysical character as follows:
-- the conductive sequence is shown in darker blue and likely
contains reduced graphite bearing units;
-- the highly magnetic units (magnetite bearing) are highlighted in stippled fill; and
-- low magnetic units and low/variable conductivity are in light blue.
Pitfield's favourable geology has attracted major mining
companies that have historically carried out preliminary
exploration activities within the area, including:
-- BHP (1984) who identified similarities between the Yandanooka
basin and African copper belt sequences and completed IP
geophysics, shallow RAB, and four stratigraphic diamond holes
focussed along the western contact of the Yandanooka basin within
the basement Mullingarra gneiss, which indicated a significant
depletion of base metals (including Cu) in the basement rock;
-- CRA (1993) which completed IP geophysics and auger sampling
defining a significant Cu-in-auger anomaly (plus Ag) over some 7km
strike length open to the east and south and they followed up with
two diamond holes, the southern hole on Pitfield recording copper
anomalism with a maximum value of 570ppm (from 4m chip samples of
drillcore) associated with fracture-controlled malachite and minor
native copper. CRA also carried out soil sampling in the Mt Scratch
area which shows a strong correlation between more strongly
anomalous copper-in-soils with magnetic units within the
stratigraphy. Rock chip samples taken by CRA from surface exposures
returned very encouraging Cu-Ag values (up to 2.3% Cu and 20.8 g/t
Ag) within the magnetic units highlighting a large, highly
prospective SSC target.
The 7km Cu anomaly in the south at Pitfield is located higher in
the sequence than the nearby historic Baxters copper mine at Arrino
(which produced 106 tonnes of copper at a grade between 20-30% Cu)
and thus more proximal to the contact between the lower red-bed
source rocks and the reduced layers in the Mt Scratch siltstone
that provide an effective redox trap for the copper fluids. This,
along with numerous other prospects including the Mt Scratch
workings in the northern section of the project licence
demonstrates that the copper mineralisation process has occurred
extensively across the Pitfield project area.
The stratigraphic mapping by BHP in the 1980s provides a very
good description of the lower "red bed" part of the Yandanooka
succession, confirming red beds of 1.0 to 1.5km in thickness,
increasing in thickness to the south and dominantly siltstone and
sandstone with local carbonate rocks in the north (Figure 4).
The geophysical surveys have confirmed that the Yandanooka basin
contains geological features that make this an attractive
sediment-hosted copper exploration target, evidenced by:
-- the Airborne Electro-Magnetic (AEM) survey which has
identified significant variations in rock conductivity including a
suite of anomalous conductive features within the Mt Scratch
siltstone, which indicates the presence of sulphides and/or
importantly reductants such as graphite.
-- the Airborne Magnetic (AM) survey which has distinguished a
widespread, stratabound, over 40km long regional magnetic anomaly
(magnetite-bearing alteration), which coincides with previously
defined copper anomalies based on historical shallow drilling and
regional rock, soil and stream sediment sampling.
Figure 4. Historic BHP stratigraphic section focussed on the
lower Yandanooka Group, 1984.
The lower +1,000m of the basin includes substantial thicknesses
of sandstone and mafic clast conglomerate which provides
copper-bearing source rocks for the basin outcropping adjacent to
and overlying the Mullingarra gneiss (refer Figure 4), while the
overlying reduced Mt Scratch siltstone acts as a redox trap for the
copper fluids mobilised from deeper in the basin. This fits the
reduced sediment hosted copper model very nicely.
The massive magnetic anomaly, extending over 40km north-south,
shows that the project area has been impacted by a large alteration
event such as the influx of warm, oxidized, metals-transporting,
sedimentary brines. It is important to note that the deeper diamond
drilling by BHP (1984) confirmed that the basement rock was
depleted in Cu, indicating that the base metals have been leached
and mobilised by the fluids passing through and most likely
explains the Cu anomalies identified within the upper zones of
siltstone/sandstone.
Further evidence of a regional scale alteration event can be
found at the adjacent Three Springs Talc Mine lying just to the
east of Pitfield. This large talc deposit was formed when hot
fluids carrying silica passed through massive dolomite formations,
leaving silica and transporting away calcium to be replaced by
magnesium - creating talc.
Comparison with other World Class Copper Provinces
The geology at Pitfield aligns closely with the SSC Model
described above and given the scale of alteration identified by the
geophysical surveys, which extends well over 40km north to south,
the project area could contain a "Giant" mineralised system which
hosts multiple SSC deposits.
SSCs have been found on every continent (except Antarctica)
however more than 80% of total resources contained in SSCs occur in
the Central African Copper Belt in the Democratic Republic of Congo
(DRC) and Zambia, and Kupferschiefer in Germany and Poland.
The most important deposits are located in the Central African
Copperbelt of Zambia and the DRC. These reduced-facies and
sandstone-hosted deposits have large tonnages and unusually high
grades (2.5%). Known resources in the belt are 152Mt contained
copper across more than 80 deposits, with the USGS estimating a
further 168Mt Cu remaining to be discovered, 75% of which is in the
DRC. These deposits are the world's main source of Co, which adds
significantly to the value of these deposits.
The recent opening of the massive Khoemacau mine in the Kalahari
Copperbelt in Botswana is a potentially significant development.
The project, which entered production in June 2021, has total
resources of 503Mt at 1.4% Cu and 17 g/t Ag.
The Kupferschiefer deposits of western Poland and eastern
Germany have produced much of Europe's Cu for more than 800 years.
The name comes from the German words for copper (Kupfer) and shale
(schiefer). Since 1958 they have produced 15 Mt Cu, with another 30
Mt awaiting development. The USGS estimates 110 Mt Cu remains
undiscovered, with the large majority in southwestern Poland.
The Revett Formation in Montana and Idaho is also known also to
host significant developed and undeveloped Cu-Ag resources in
sandstone-style deposits. However, given the geological setting at
Pitfield the most obvious comparison, on a worldwide, large scale
basis, is Udokan.
The Udokan mine is a large copper mine located in the south of
Russia in Zabaykalsky Krai, around 30 km south of the town of
Novaya Chara on the Baikal Amur Mainline. The mine is part of the
massive Udokan Ore Region that includes the Udokan, Kalar and Kodar
ranges. The Udokan Ore Region represents the largest copper deposit
in Russia and third largest in the world, having estimated reserves
of 1.2 billion tonnes of ore grading 2% Cu.
Udokan has several key features which are common to Pitfield,
including:
-- Udokan is a sandstone sub-type of SSC deposits;
-- Copper mineralisation assemblages are of three types;
o chalcocite-bornite, always associated with magnetite, and
makes up >80% of the potentially economic primary resource
o chalcopyrite-bornite or
o chalcopyrite-pyrite
-- Within higher grade chalcocite-bornite mineralisation,
sulphide or quartz-carbonate-epidote-sulphide veins with magnetite
haloes crosscutting or sub-parallel to bedding are always present
in association with the dominant bedding-parallel disseminated to
stringer sulphides;
-- Individual orebodies are 300 - 2,000m in strike, can continue
for up to 2,500m down-dip, and 16-52m in thickness; and
-- Main mineralisation is Cu-Ag-Fe, minor Co, Ni, Zn, Mo, Au
Figure 5: Udokan deposit geologic map and cross sections, where
red denotes a bornite-chalcocite-chalcopyrite ore body.
Market Abuse Regulation (MAR) Disclosure
Certain information contained in this announcement would have
been deemed inside information for the purposes of Article 7 of
Regulation (EU) No 596/2014, as incorporated into UK law by the
European Union (Withdrawal) Act 2018, until the release of this
announcement.
**S**
For further information please visit www.empiremetals.co.uk or contact:
Empire Metals Ltd Tel: 020 7907 9327
Shaun Bunn / Greg Kuenzel
S. P. Angel Corporate Finance LLP Tel: 020 3470 0470
(Nomad & Broker)
Ewan Leggat / Adam Cowl
-------------------
Shard Capital Partners LLP (Joint Tel: 020 7186 9950
Broker)
Damon Heath
-------------------
St Brides Partners Ltd (Financial Tel: 020 7236 1177
PR)
Susie Geliher / Ana Ribeiro / Max
Bennett
-------------------
About Empire Metals Limited
Empire Metals is an AIM-listed (LON: EEE) exploration and
resource development company with a project portfolio comprising
gold interests in Australia and Austria.
The Company's strategy is to develop a pipeline of projects at
different stages in the development curve. Its initial focus has
been on the high-grade Eclipse and Gindalbie Gold Projects in
Western Australia. The Company expanded its exploration licence
area in April 2022 from 9.5km(2) to 1,728km(2) with the acquisition
of the Pitfield Copper-Gold Project and the Walton Copper-Gold
Project in Western Australia, and the Stavely Copper-Gold Project
in the Stavely Arc region of Victoria.
Empire also holds a portfolio of three precious metals projects
located an historically high-grade gold production region
comprising the Rotgulden, Schonberg and Walchen prospects in
central-southern Austria.
The Board continues to evaluate opportunities through which to
realise the value of its wider portfolio and reviews further assets
which meet the Company's investment criteria.
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