REG - Tertiary Minerals - Exploration Update – Brunton Pass Project, Nevada

Tertiary MineralsAnnouncement

01/11/2022 07:00

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RNS Number : 7969E  Tertiary Minerals PLC  01 November 2022

 

("Tertiary" or "the Company")

 

AIM Announcement                                                1 November 2022

 

 

Exploration Update - Brunton Pass Project, Nevada, USA

 

Tertiary Minerals plc is pleased to provide the following update on its summer
exploration campaign at the Brunton Pass Copper-Gold Project in Nevada, USA.

 

 

Highlights

 

·    The programme included trenching, sampling, geochemical analysis,
petrological evaluation and field follow up.

 

·    Six trenches (T1, T2, T7, T8, T10 and T11) were completed for a
combined length of 386m to further evaluate previously reported copper,
mercury and arsenic anomalies in soil and surface rock chip samples.

 

Copper Targets

 

·    Wide intervals of low-grade copper observed in trenches T7 and T8:

Ø 27.4m grading 1,010ppm copper (0.1% Cu) in T7, open to the east.

Ø 77.7m grading 473ppm copper in T8 open to the east.

 

·      Petrological evaluation has confirmed the copper is associated
with widespread garnet-pyroxene skarn alteration adjacent to diorite
intrusives.

 

·      These wide low-grade copper intervals are a possible halo to more
significant mineralisation and suggest the possible presence of a deeper
porphyry copper target.

 

Gold Target

 

·    Two trenches (T1 & T11) testing the north and south ends of a
1.2km long zone of mercury-arsenic soil anomalies intersected substantial
widths of hydrothermally altered rock with approximately 1,000 times
background content of the gold indicator elements, arsenic and mercury:

Ø 9.1m grading 1,930ppm arsenic and 102 ppm mercury in T1

Ø 32m grading 1,622ppm arsenic and 110ppm mercury T11

 

·    T2, located between T1 and T11, intersected 2.65g/t gold over 2.7m.

 

·      The north trending zone tested by T1, T2 and T11 will now be
drill tested for epithermal gold mineralisation at deeper levels.

 

Commenting today, Executive Chairman Patrick Cheetham said: "We are pleased to
be reporting a successful summer programme at our Brunton Pass Project in
Nevada.

 

The occurrence of substantial widths of clay altered rock with up to 1,000x
background values for mercury and antimony at two locations 900m apart and
with gold values up to 2.65g/t gold suggests these trenches may be in the
upper levels of a high sulphidation epithermal gold deposit. Similar deposits
occur in the area including the Paradise Peak deposit, 25km to the southeast,
which produced over 1.6 million ounces of gold and over 44 million ounces of
silver before closing in 1993.

 

This epithermal alteration is superimposed on a large area of skarn alteration
prospective for copper and may also suggest the presence of a larger porphyry
copper target nearby.

 

We will now move forward with drill planning at Brunton Pass and look forward
to reporting back on progress."

 

For more information please contact:

 

 Tertiary Minerals plc                  Tel: +44 (0)1625 838 679

 Patrick Cheetham, Executive Chairman

 S P Angel Corporate Finance LLP        Tel: +44 (0)203 470 0470

 Nominated Adviser & Broker

 Richard Morrison/Caroline Rowe

 Peterhouse Capital Limited             Tel: +44 (0)207 469 0930

 Joint Broker

 Lucy Williams/Duncan Vasey

 

AIM:  TYM | Find out more at tertiaryminerals.com

 

Market Abuse Regulation (MAR) Disclosure

The information contained within this announcement is deemed by the Company to
constitute inside information as stipulated under the Market Abuse Regulations
(EU) No. 596/2014 which forms part of UK domestic law by virtue of the
European Union (Withdrawal) Act 2018 ('MAR'). Upon the publication of this
announcement via Regulatory Information Service ('RIS'), this inside
information is now considered to be in the public domain.

Note to Editors

Tertiary Minerals plc (LON: TYM) is an AIM traded mineral exploration and
development company whose strategic focus is on energy transition metals. The
Company's projects are located in stable and democratic, geologically
prospective, mining-friendly jurisdictions. Tertiary's current principal
activities are the discovery and development of mineral resources in Nevada,
USA and in Zambia.

 

Detailed Information

Background

The Brunton Pass Project is located in central Nevada and was acquired in 2021
after sampling of prospector small-scale surface workings revealed high copper
values. Reconnaissance rock chip sampling and mapping were subsequently
carried out throughout the claim block returning values up to 6.84% copper and
1.75 g/t gold in separate samples as well as anomalous silver values.

A drone magnetic and photogrammetric survey was also carried out in 2021 and
the data was subsequently processed using magnetic vector inversion modelling.

Mineralisation at Brunton Pass is closely associated with hornfels and skarn
alteration of a mixed sequence of Triassic aged carbonate and clastic
sediments that form a 1.8km x 0.75km, uplifted "window" (horst block) in fault
contact within younger Tertiary-age volcanic rocks. The magnetic inversion
model suggests that the Triassic sediments may be underlain at shallow depth
by a large intrusive body that could be the source of the alteration and
mineralisation. Evidence for this underlying body is found in surface outcrops
of granite/granodiorite and at least two phases of diorite intrusion.

Following initial prospecting a total of 485 soil samples were collected at
50m spacing on lines 100m apart over the main window and on a 100m by 100m
offset grid over the remainder of the project area.

Several copper-in-soil anomalies(1) with individual grades of up to 953ppm
copper were delineated based on this sampling. The largest of these anomalies
in the southwest quadrant of the property has dimensions of 340m x 310m and
they are mainly coincident with areas where rock grab samples contain
percent-level copper values in small prospecting pits.

Two large mercury and arsenic in soil anomalies(1) were also defined in the
eastern half of the property in a north trending zone with values up to 52 ppm
mercury with the largest of these extending over an area approximately 500m x
500m. These anomalies are centred on a north trending zone of structural
dislocation with a strike length of at least 1.2km entirely within the project
area.

 

Summer 2022 Trenching Programme

In late July 2022, Tertiary contracted Legarza Exploration LLC ("Legarza") to
conduct a trenching programme at the Brunton Pass Copper Project under the
supervision of contract geologist Ivan Johnson.

Six trenches were excavated for a total of 386.2 metres over the zones of
anomalous copper arsenic and mercury anomalies. All trenches were geologically
mapped and sampled throughout at 10ft (3m) intervals. The trenches were
numbered according to a provisional plan and as not all planned trenches were
dug, trench numbers described below do not run sequentially.

Trenches T1, T2 and T11 were excavated in the eastern half of the project area
in the area of the mercury-arsenic anomalies, whilst trenches T7, T8 and T10
targeted the copper soil anomalies in the southwest quadrant of the project.

Trench walls were photographed and samples sent to Paragon Geochemical
Laboratories, Reno for sample preparation and analysis. Samples were analysed
via method FSAu-25, an aqua regia digest multi-element analysis which includes
gold. Laboratory QA/QC samples were inserted into the sample run.

Multiple rock samples from trenches and outcrop were sent for thin section,
polished thin section and XRD evaluation to evaluate the styles of
mineralisation and so provide context for trench sampling analytical results.

 

Trench 1 (67m long) targeted the northern extent of the mercury-arsenic
anomaly in the north part of the project area where previous rock chip
sampling yielded values of up to 0.1% copper in a silicious jasperoid. T1 cut
through a 30m wide carbonate sequence which is in fault contact on its east
side with Tertiary volcanics and on the west side with a 12m wide fault sliver
of granitic rock that lies along the eastern contact with Tertiary volcanics.

All of the rock units in T1 display intense argillic alteration containing
smectite (-illite), quartz and opal/cristobalite.

The clay altered sediments adjacent to the granite also contain hematite and
goethite and geochemical analysis shows high arsenic (As) and mercury (Hg)
values with a 9.1m section containing 1,930ppm As and 102ppm Hg.

These values are similar to the wider As-Hg zone described for Trench 11
approximately 875m further south (see below) and are approx. 1,000 times the
geochemical background levels found in other areas of the project.

 

Trench 2 (33.5m long) was excavated in hornfels towards the centre of the same
mercury-arsenic anomaly tested in T1. The hornfels contains bands of andradite
garnet and diopside and is not as altered as in 1 and T11, most likely due to
lower permeability of the hornfels to hydrothermal fluids.

T2 intersected 2.7 metres grading 2.65 g/t gold in a north trending shear zone
that parallels the strike of the soil anomaly. Gold may have been remobilised
into this structure from a deeper level (see concluding remarks below).

 

Trench 7 (109.7m long) was designed to cut across one of the peak
copper-in-soil geochemical anomalies in the southwest quadrant of the project
area and to continue to the western contact of the sediments with the Tertiary
volcanics on the west side of the window.

From east to west Trench 7 intersected a sequence of skarn and variably
altered sediments in fault contact with a 20m wide sliver of quartz diorite
which is itself in fault contact with Tertiary volcanics at the east end of
the trench.

Beneath the peak soil anomaly T7 cut 27.4m grading 1,010ppm copper (0.1% Cu)
within a 45.7m wide intersection grading 814ppm copper which is highly
anomalous.  This zone is also open to the east.

The sequence is variably silicified and altered with significant smectite
(nontronite), illite quartz and opal in places.  Potassic alteration
(K-feldspar) is also evident in thin section examination.

 

Trench 8 (77.7 m long) is located 40m south of, and was excavated roughly
parallel to, T7.

T8 intersected a much thicker zone of diorite in fault contact with the
Tertiary volcanics on the west side of the window. The diorite also contains
fault slivers of hornfels and xenoliths of altered skarn. The remainder of the
trench intersected strong skarn alteration.

The whole trench, 77.7m, averaged 473ppm copper, which is again highly
anomalous. T8 also illustrates the spotty nature of the higher-grade copper
mineralisation near surface with corresponding samples on the opposite wall of
the trench for one particular 10ft interval grading 4.85% copper on the south
wall side and less than 1,000ppm copper on the north side.

 

Trench 10 (63.1m long) was designed to excavate across a weakly mineralised
occurrence of jasperoid (BR4) where a grab sample assayed 0.3% copper that
occurs within the same broader copper soil anomaly tested by T7 and T8.

T10 intersected a magnesian pyroxene-phlogopite skarn within a broader zone of
calc-silicate hornfels and sandstone containing lower copper values than in T7
and T8.

The trench was notable however for a 7m wide section of fault bounded Tertiary
volcanics, west of which the last 11m of the trench is heavily stained by iron
oxides most likely due to a high content of garnet skarn as massive garnet
skarn outcrops just south of T10.

 

Trench 11 (32m long) was excavated to test across the central part of the
southern 500m long arsenic-mercury soil anomaly where previous mapping rock
samples were also anomalous in As and Hg.

The trench cut through a sequence of strongly clay altered sediments
(sandstone and siltstone) and the entire trench was anomalous in arsenic and
mercury with 32m grading 1622ppm As and 110ppm Hg (approx. 1,000x background).
XRD analysis on assay pulps from two sample intervals contained 46-55%
smectite whilst one of the samples contained 28% garnet and the other 18%
opaline quartz/cristobalite.

As with T2, these petrological and geochemical characteristics define a zone
of argillic alteration characteristic of the upper levels of an epithermal
hydrothermal system superimposed on an earlier phase of skarn alteration.

 

Concluding Remarks

Regionally the Brunton Pass deposit sits on the north-east side of a large
granite batholith around which there are a number of epithermal gold and
porphyry copper-gold deposits including the high sulphidation Paradise Peak
gold deposit, 25km southwest of Brunton Pass, that produced over1.6 million
ounces of gold and over 44 million ounces of silver and at least 457 tons of
mercury and which exhibits the similar argillic alteration assemblages
(smectite+quartz+/-opal ) seen in T1 and T11.

The work undertaken during this field season suggest the possible presence of
a porphyry copper target and epithermal gold mineralisation at deeper levels
and the Company believes that drill testing of these copper and gold targets
is now warranted.

A map showing Brunton Pass Project soil sampling anomalies and trenching is
available on the Company's website at:

https://www.tertiaryminerals.com/filemanager/BruntonPass/Soil_sampling_anomalies_and_trenching_map.jpg
(https://www.tertiaryminerals.com/filemanager/BruntonPass/Soil_sampling_anomalies_and_trenching_map.jpg)

 

Notes:

1.   Anomalous soil samples are defined in this case by the 90(th)
percentile values of the soil value population, being 55 parts per million
copper and 740 parts per billion mercury.

 

2.   The information in this release has been compiled and reviewed by Mr.
Patrick Cheetham (MIMMM, MAusIMM) who is a qualified person for the purposes
of the AIM Note for Mining and Oil & Gas Companies. Mr. Cheetham is a
Member of the Institute of Materials, Minerals & Mining and also a member
of the Australasian Institute of Mining & Metallurgy.

 

3.   The news release may contain certain statements and expressions of
belief, expectation or opinion which are forward looking statements, and which
relate, inter alia, to the Company's proposed strategy, plans and objectives
or to the expectations or intentions of the Company's directors. Such
forward-looking statements involve known and unknown risks, uncertainties, and
other important factors beyond the control of the Company that could cause the
actual performance or achievements of the Company to be materially different
from such forward-looking statements. Accordingly, you should not rely on any
forward-looking statements and save as required by the AIM Rules for Companies
or by law, the Company does not accept any obligation to disseminate any
updates or revisions to such forward-looking statements.

 

 

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