GT Gold Corp. (TSX-V:GTT)
(the
“Company” or “GT Gold”) is pleased to provide a
summary of its completed geological model for the Saddle North
gold-rich copper porphyry discovery, as well as an overview of the
2020 exploration plan to drill untested high-priority targets on
the Tatogga property in the prolific Golden Triangle of northern
British Columbia.
“The company has reached another milestone with
the delivery of a robust geological model, which now provides the
strong foundation on which to estimate the initial mineral resource
for the Saddle North, greenfields porphyry copper discovery. The
model is supported by the integration of numerous empirical data
sets”, commented Paul Harbidge, President and CEO. “We’re also very
pleased to report plans to test the exciting new targets at Tatogga
in the upcoming exploration season. We’re wrapping up one resource
and determined we’ll find another in a region that is beginning to
show the signs of a new porphyry district.”
Summary
This report details the work undertaken to
develop a geological model to understand the controls on
mineralization for the recently discovered Saddle North gold-rich
copper porphyry in northern British Columbia. A total of 31,397
metres of drill core was relogged in detail over the past four
months to develop a robust three-dimensional geological model for
Saddle North. This involved the production of hand drawn
cross-sections and level plans at 100 metre intervals through the
kilometre-scale mineralized zone for lithology, alteration,
mineralization and structure, and was complemented by a thorough
assessment and classification of the Company’s large database of
geochemical data. The resultant plans and sections were then
scanned, georeferenced and integrated with magnetic and Induced
Polarization data to create a well-constrained three-dimensional
digital model. The model will be used as the basis for the
Company’s initial mineral resource estimate, due to be released by
the end of June 2020, and both will underpin a Preliminary Economic
Assessment for Saddle North expected to be released by year-end,
2020.
- Saddle North is a gold-rich copper porphyry centered on a
series of pre-mineralization to late inter-mineralization
monzodiorite and monzonite intrusions. The intrusive complex is
interpreted to represent a series of igneous bodies emplaced over a
relatively short period of time in the late Triassic. Minor
post-mineralization felsic and mafic dykes have also been
observed.
- Copper and gold mineralization in the porphyries varies with
the intrusive phases and is associated with stockwork and sheeted
quartz-pyrite-magnetite-chalcopyrite vein zones, with the highest
grades occurring where the vein densities are greatest. Almost all
the copper is contained in chalcopyrite. Additional copper may be
related to minor occurrence of tennantite together with
chalcopyrite in late quartz-carbonate-sericite veins.
- Geochemistry and spectral data reveal that high copper and gold
grades are also closely associated with high-temperature potassic
alteration assemblages (potassium feldspar, biotite and magnetite).
Abundant secondary and local primary biotite has been almost wholly
replaced by chlorite-phengitic muscovite, and the high-temperature
alteration in places has been overprinted by quartz-sericite
(muscovite)-pyrite alteration.
- The mineralized zone is limited by the northwest-southeast
oriented, steeply southwest dipping Poelzer fault. The footwall
country rocks to the fault are not well-mineralized but are
characterized by widespread quartz-sericite-pyrite alteration and
the local presence of pyrophyllite and kaolinite, which are typical
in the shallow portions of porphyry systems. This highlights
additional exploration potential along strike and at depth across
the Poelzer fault.
- Compared to other porphyry systems, Saddle North appears to be
hosted in a relatively straightforward alteration system with
minimal clays and localized low to moderate arsenic.
The Company continues to generate exploration
targets on the Tatogga property, in part by undertaking further
greenfields-style exploration (soil geochemistry, Induced
Polarization surveys and field mapping), as well as reassessing the
substantial historical exploration datasets gleaned from Assessment
Reports for the district, which have been archived by the Ministry
of Mines of B.C. The combined datasets include soil, stream, and
rock geochemistry, as well as geophysical data in the form of a
number of merged regional airborne magnetic surveys, new
property-scale detailed airborne magnetic, radiometric (gamma), and
“Mobile MT” surveys, plus regional gravity data and several new
ground-based Induced Polarization (IP) surveys.
The results of this work highlight two main
areas for follow-up in the 2020 summer field program:
- The greater Saddle area; adjacent to the known Saddle North and
Saddle South discoveries, where four principal targets have been
outlined.
- The Quash-Pass area, where two large-scale anomalous trends and
several adjacent individual target areas have been defined.
An initial 10,000 metre diamond drill program
has been budgeted as a first phase of following on these high
priority targets.
Saddle North Technical Session
Webcast
The Company will host a technical webcast
scheduled for April 29, 2020 at 10:00am Pacific (1:00pm Eastern) to
present the geological model and review exploration plans.
Participants may access the webcast call as follows:
- Online on the Company website at www.gtgoldcorp.ca or via
the direct link: https://edge.media-server.com/mmc/p/8dkog46v
- By phone at 1-888-337-1150 toll free in Canada or the U.S., or
at 1-956-394-3454 internationally.
- A recorded playback of the conference call will be available
until May 6, 2020 by calling toll free 1-855-859-2056, or
1-404-537-3406 outside of the U.S. and Canada, conference ID
3484372. An archived webcast will also be available for 12 months
at www.gtgoldcorp.ca.
Saddle North 3D Geological
Model
A slide deck for public viewing of the 3-dimensional model
showing the Saddle North mineralization, lithology and alteration
can be accessed at the VRIFY link here: https://vrify.co/GTGold
Saddle North Re-Logging
Program
All of the Saddle North drill core, amounting to
31,397 total metres, was relogged at the company’s core facility
(Figure 1) following the shut down of the field program in late
October 2019. The relogging program was completed in mid-February
2020, with the overall aim of generating a geological model that
will support initial mineral resource estimates, due later in this
second quarter of 2020. A Preliminary Economic Assessment is also
planned to be released by the end of 2020.
Figure 1 is available at
https://www.globenewswire.com/NewsRoom/AttachmentNg/988b8fd3-034f-49a0-8e5b-54adbdd0a16c
Methodology
In addition to visual re-logging of the core,
multi-element geochemistry and modelled geophysical data was used
to delineate the various lithological units, alteration types, and
structures. A series of hand drawn cross sections and level plans
(Figure 1) were completed for lithology, structure, alteration and
mineralization. These were then scanned and georeferenced for
manipulation using Seequent’s Leapfrog software to construct
digital solids for each layer of the geological model (Figure
2).
Figure 2 is available at
https://www.globenewswire.com/NewsRoom/AttachmentNg/97ac0d96-a474-4223-bbce-d17a9be20bd9
Lithology
Saddle North is a gold-rich copper porphyry
centered on monzodiorite and monzonite intrusions (Figure 3). The
intrusive complex is interpreted as a series of igneous bodies that
intruded volcanic rocks of the Upper Triassic Stuhini Group over a
short period of time, which led to local brecciation and
co-mingling of magmas. The intrusive complex and its host rocks are
overlain, unconformably on their northeastern and northern margins,
by volcaniclastic and local volcanic rocks of the Lower Jurassic
Hazleton Group.
Specific immobile trace element ratios (e.g.,
Zr/Ti, Cr/Al, Th/Ti) aided greatly in outlining and differentiating
lithologies, especially the different porphyry phases (Figure 3),
and the approach was validated by principal component analysis
(PCA) based classification of the rocks, which employed Al, Ce, Cr,
Ga, Ge, Nb, P, Sc, Ti, Th, Zr, Ta, V, Ni, and Y. The immobile
element ratio and PCA approach separated the porphyries into a
total of eight phases; six pre-mineral (P0-P5) and two
inter-mineral phases (I1 and I2). The inter-mineral porphyries are
the most recognizable lithologies at Saddle North, and have
distinctive geochemistry and are interpreted as individual pencil-
to tabular-shaped intrusions with smaller irregular apophyses.
Inter-mineral I1 can carry some mineralized veining and Au and Cu
grades. A number of younger post-mineral mafic to felsic dykes are
also present and are represented in the plots in figure 3 they are,
however, insignificant in terms of volume and are not shown in
figure 4.
Figure 3 is available at
https://www.globenewswire.com/NewsRoom/AttachmentNg/aae93da5-4ec3-4d89-9231-8d78da677f83
Figure 4 is available at
https://www.globenewswire.com/NewsRoom/AttachmentNg/99d9a80f-3774-4c9e-bf9c-ca16b6591559
Alteration
Six alteration styles were recognized and
quantified in the relogging program. The relogging was supplemented
by systematic collection of downhole hyperspectral data, which was
processed via aiSIRIS, and CoreScan imagery for a number of Saddle
North holes, as shown in Figure 5, along with petrography. The
alteration phases include potassic, quartz-sericite-pyrite (QSP),
chlorite-sericite, weak to trace intermediate-argillic, propylitic,
and sodic-calcic (Figure 6). Each phase was developed with
iso-shells representing intensities ranging between strong (5) to
weak (1) and absent (0). The resulting model depicts a
well-developed, steeply plunging potassic core that is associated
with the highest-grade mineralization, and which lies within the
bounds of intense QSP alteration, which shoulders the potassic
alteration core (Figure 6). Alteration phases commonly overlap with
one another and as a result each style was modelled independently
in Leapfrog.
Figure 5 is available at
https://www.globenewswire.com/NewsRoom/AttachmentNg/db633cfa-372e-4633-b847-3f4ba876c262
Figure 6 is available at
https://www.globenewswire.com/NewsRoom/AttachmentNg/8043c931-442e-4fe6-8608-75d7bc2122a1
Potassic
Alteration
Potassic alteration is the dominant style of
alteration associated with mineralization and grade at Saddle
North. It is defined by the presence of secondary potassium
feldspar, biotite (typically completely altered to
phengitic-muscovite and chlorite), and magnetite, and is associated
with intense A-type quartz-magnetite-sulphide quartz vein
stockworks that carry higher-grade gold and copper. Potassic
alteration is limited to the hangingwall of the Poelzer fault and
therefore the fault was set as a hard boundary to the model. The
geometry of the potassic alteration plunges steeply to the
southwest, along the general orientation of interpreted porphyry
emplacement.
Quartz-sericite-pyrite
(QSP)
Quartz-sericite-pyrite alteration, also commonly
referred to as phyllic alteration in porphyry literature, is an
intense hydrothermal alteration that can be found both above and on
the shoulders of the potassic core of the Saddle North porphyry
system. This alteration zone is characterized by the abundance of
quartz, sericite and pyrite minerals. At Saddle North, intense QSP
alteration is most notable in two places: 1) in the hangingwall of
the Poelzer fault it lies on the periphery of the mineralized
system where it overprints potassic alteration, and 2) in the
immediate footwall of the Poelzer fault, where pervasive and
intense QSP alteration of the Stuhini Group produces mineralogical
but not textural replacement of the Stuhini Group
volcani-sedimentary sequence and associated porphyritic intrusions,
and where it commonly grades outward into propylitic
alteration.
Other Alteration
Styles
Other alteration styles were also modelled with
the same methodology but with less meaningful results.
Chlorite-sericite alteration proved to be ubiquitous. It is
particularly common in the upper levels of the system, where it
overprints all other alteration styles and essentially outlines the
intrusive system itself. In detail, this style of alteration is
manifest as chlorite after mafic minerals, sericite after
feldspars, and hematite after magnetite. It bears a common
association with narrow pyrite veinlets and disseminated
pyrite.
The propylitic alteration model, characterized
by the presence of epidote and chlorite, displays a significant
correlation with both post-mineral dykes and with one of the
inter-mineral porphyry phases (I1). Within the Saddle North
mineralized system it is typically weak in intensity and does not
appear to influence grade. It is also present locally in the rocks
in the footwall of the Poelzer fault.
Mineralization
Copper sulfide mineralization, dominantly
chalcopyrite, is disseminated, occurs in quartz veins, and in
microfractures. Quartz veins range from microveinlets about a
millimetre thick to domains of quartz flooding several centimetres
thick. The veins can be wavy and anastomosing, or form intricate
stockworks, and most may be characterized as A-veins. In
mineralized A-veins, fine specks or coarser blebs of chalcopyrite,
+/- magnetite exist. Zones of higher A-vein density result in
increased grade.
Pyrite occurs commonly as very fine to
coarse-grained, anhedral to euhedral disseminations, fracture
fillings, and veins. It ranges from less than 1% to over 10% and is
quite ubiquitous within the bounds of the model. Late-stage pyrite
(± minor chalcopyrite) veins cut quartz vein stockworks and with
sericitic-argillic alteration are particularly common in the upper
levels of the mineralized system, these represent classic
D-veins.
There is a clear association of copper and gold
grades with potassic alteration, and this is commonly overprinted
by an assemblage of phengitic white mica and chlorite (Figure 7).
Thus, the bulk of the copper and gold mineralization appears to
have been introduced relatively early in the evolution of the
Saddle North porphyry system.
Mineralogy calculated from 4-acid ICP-MS data as
well as petrographic studies suggest that almost all the copper is
contained in chalcopyrite. Additional copper may be related to
minor occurrences of tennantite which may occur together with
chalcopyrite in late carbonate-sericite veins.
Figure 7 is available at
https://www.globenewswire.com/NewsRoom/AttachmentNg/21b7fa39-c97a-4b94-a03b-1a32016e4c3a
Structure
During the core-logging at Saddle North,
structural data was collected from drill core and documented in
four components: 1. Structure Type (Fault zone, Fracture zone, Late
Carbonate-Quartz-Chalcopyrite (Cbn-Qtz-Cpy) veins), 2. Structure
Intensity (measured on a scale of 1 (trace) to 5 (intense)), 3.
Structure Style (Brittle, Ductile, Shear), and 4. Interval Length
(metres).
Occurring as a relatively mobile element,
arsenic values were plotted downhole to test the hypothesis that
elevated values could potentially outline the presence of faults.
While arsenic did appear to correlate locally with zones of low
Rock Quality Designation (RQD) values and simplified range
structures, the correlations were too inconsistent to be considered
universally applicable at Saddle North and were therefore not used
directly in the structural interpretation.
In the structural model for Saddle North (Figure
8), the principal structural features are: 1) the well-defined and
very predictable Poelzer fault, a strongly foliated zone which
forms the footwall to the presently known mineralized zone, and 2)
the similarly relatively planar and apparently predictable brittle
fractured Southern fault, which marks the southern contact of the
Saddle North porphyritic intrusive rocks with their host Stuhini
Group volcanic rocks. Less well-defined structures, also defined
more by brittle fracturing, include what is referred to as the
“Southern Crush Zone,” which dips to the northeast and lies near
the southwestern margin of the Saddle North zone, and a number of
north-northwest to northwest trending, steeply southwest-dipping
brittle fracture zones which are likely anastomosing and that lie
between the aforementioned features.
Figure 8 is available at
https://www.globenewswire.com/NewsRoom/AttachmentNg/4d89f91a-57b6-4b86-9eb1-9e8c13cb2673
Transition-fresh rock
boundary
There is no true weathered oxide zone developed
at Saddle North. The transition zone is characterised by variably
mild oxidation of sulphide minerals and limonite development on
fractures and ranges and varies between 11 metres to 105 metres
thick. Below the transition zone only fresh rock is present.
Property-Scale Exploration
GT Gold continues to generate exploration
targets on the Tatogga property. In part by interpreting the data
collected by the Company on the property, as well as by revisiting
the relatively vast previous exploration datasets gleaned from
Assessment Reports for the district, archived by the Ministry of
Mines of B.C. The datasets included soil, stream, rock
geochemistry, geophysical data (merging of a number of regional
airborne magnetic surveys, property-scale detailed airborne
magnetic, radiometric (gamma), and “Mobile MT” surveys, plus
regional gravity data and ground based Induced Polarization (IP)
surveys.
- The results of this work highlight two main areas: The greater
Saddle area; adjacent to the known Saddle North and Saddle South
discoveries, where four principal broad targets have been
outlined.
- The Quash-Pass area, where two large-scale anomalous trends and
several adjacent individual target areas have been defined.
An initial 10,000 metre diamond drill program
has been budgeted, as a first phase of follow-up, on these two high
priority target areas, planned for the summer 2020 field
campaign.
Saddle Area
- The Saddle North copper gold porphyry mineralization returns a
strong chargeability anomaly from Induced Polarization geophysical
surveys, which extends over 3 kilometres. There is a limited
geochemical response due to thicker colluvial cover. Drilling to
date has not drilled beyond the mineralized envelope and has not
fully tested the geophysical anomaly. The extensions and presence
of additional porphyries remains a high priority target
- At the Northwestern end of the Saddle North trend, which lies
due north of the Saddle South mineralized system, the potential is
highlighted by a plus 2 kilometre high-tenor gold-in-soil
geochemical anomaly, as well as by a continuous linear
chargeability anomaly and associated magnetic highs (Figure 9).
This area has only been tested by limited previous drilling but
encouraging results were returned from drill hole TTD17-064 which
yielded 1.35 g/t Au, 1.42 g/t Ag, and 0.37% Cu over 18.40 metres
from 134.60 metres (est. 90% true width), including 2.28 g/t Au,
2.03 g/t Ag and 0.56% Cu over 7.40 metres from 134.60 metres, that
coincided with sheeted vein-style mineralization hosted by
high-temperature potassic alteration developed within porphyritic
intrusive rocks (refer to GT Gold news release dated December 13,
2017).
- The Central target locates between Saddle North and South and
highlights where these two systems intersect and coincides with a
geochemical as well as chargeable geophysical anomaly and remains
untested by drilling.
- The southern target is low priority but is represented by a
strong geophysical response from the Induced Polarization
survey.
Figure 9 is available at
https://www.globenewswire.com/NewsRoom/AttachmentNg/f0e31d55-1a12-4cbc-9497-499722ffbc50
At Quash-Pass, the multi-element soil
geochemical anomalies stretch over a strike length of at least six
kilometres and remain open (Figure 10). In addition, Induced
Polarization geophysical surveys return coincident chargeability
anomalies, while structural interpretations reveal district scale
West-Northwest trending faults and outcrop mapping show the
presence of moderately abundant iron carbonate alteration and
associated veining. This high priority area has previously not been
drill tested.
Figure 10 is available at
https://www.globenewswire.com/NewsRoom/AttachmentNg/a2585568-7097-4c3c-9c68-821313ce80b2
References
Middlemost, E.A.K., 1994. Naming Material in the
Magma/Igneous rock system. Earth Science Reviews, Volume 37, Issues
3-4, pp. 213-224.
Pearce, J.A., 1996. A user’s guide to basalt
discrimination diagrams. Trace element geochemistry of volcanic
rocks: applications for massive sulphide exploration. Geological
Association of Canada, Short Course Notes, 12, pp.79-113.
QA/QC Procedures
GT Gold has implemented a rigorous quality
assurance / quality control (QA/QC) program to ensure best
practices in sampling and analysis of diamond drill core, the
details of which can be viewed on the Company's website at
http://www.gtgoldcorp.ca/projects/tatogga/. All assays are
performed by ALS Global Ltd., with sample preparation carried out
at the ALS facility in Terrace, BC, and assays determined mainly at
the North Vancouver laboratory. For gold, fire assays are performed
as per ALS method Au-AA26 (0.01 - 100 g/t Au) using 50 grams of
sample measured by atomic absorption. Assays equal to or greater
than 100 g/t Au are reanalyzed gravimetrically by method Au-GRA22.
Silver and copper are analyzed by ALS method ME-MS61 with a 4-acid
digestion followed by ICP-MS analysis. Assays greater than 100 ppm
silver or 1% copper are reanalyzed by ICP-AES by method OG-62.
Qualified Person
Michael Skead, FAusIMM, Vice President, Project
Development for GT Gold Corp., is a qualified person under NI
43-101 and has reviewed and approved all other contents of this
report.
About GT Gold
GT Gold Corp. is focused on exploring for base
and precious metals in the geologically fertile terrain of British
Columbia’s renowned Golden Triangle. The Company’s flagship asset
is the wholly-owned, 46,827 hectare Tatogga property, located near
Iskut, BC, upon which it made two significant discoveries in 2017
and 2018 at its Saddle prospect: a precious metal rich vein system
at Saddle South and a gold-rich copper porphyry at Saddle
North.
For further information, please contact:
GT
Gold Corp.Paul HarbidgePresident and Chief
Executive OfficerTel: (236) 427 5744Website:
www.gtgoldcorp.ca |
GT
Gold Corp.Shawn CampbellChief Financial
OfficerTel: (236) 427 5744 |
Cautionary Statement Regarding Forward
Looking Statements
This news release contains forward-looking
statements and forward-looking information (together,
"forward-looking statements") within the meaning of applicable
securities laws. All statements, other than statements of
historical facts, are forward-looking statements. Generally,
forward-looking statements can be identified by the use of
terminology such as "plans", "expects”, "estimates", "intends",
"anticipates", "believes" or variations of such words, or
statements that certain actions, events or results "may", "could",
"would", "might", "will be taken", "occur" or "be achieved".
Forward looking statements involve risks, uncertainties and other
factors disclosed under the heading “Risk Factors” and elsewhere in
the Company’s filings with Canadian securities regulators, that
could cause actual results, performance, prospects and
opportunities to differ materially from those expressed or implied
by such forward-looking statements. Although the Company believes
that the assumptions and factors used in preparing these
forward-looking statements are reasonable based upon the
information currently available to management as of the date
hereof, actual results and developments may differ materially from
those contemplated by these statements. Readers are therefore
cautioned not to place undue reliance on these statements, which
only apply as of the date of this news release, and no assurance
can be given that such events will occur in the disclosed times
frames or at all. Except where required by applicable law, the
Company disclaims any intention or obligation to update or revise
any forward-looking statement, whether as a result of new
information, future events or otherwise. Neither the TSX Venture
Exchange nor its Regulation Services Provider (as that term is
defined in the policies of the TSX Venture Exchange) accepts
responsibility for the adequacy or accuracy of this
release.
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